[p.T] Petroleum Development Geology

8/8/2019 [p.T] Petroleum Development Geology

http://slidepdf.com/reader/full/pt-petroleum-development-geology 1/371

YOGYAKARTA, JUNE 2008

MM DARISSALAM





1. Angkatan ‘71

Teknik Geologi UGM(8 years + 3 months)

2. Oil Industry1. 24+ years in 7 oil coy’s.)

2. 7 years Petroleum Consultant

3. Terakhir

PSC Tropik Energi



References & Sources of Presentation Materials

• Shlumberger : Oil Field Review, Short Courses & Promotions slides,Manuals, Publications, etc.

• Baker Hudges : Publications & Manuals• Halliburton : Published slide and books• Publications & In-house Training materials from: TOTAL, Chevron,

Texaco etc.• AAPG & SPE journals & slides bank• Literatures:

– Development Geology P Dikey – Development Geology Reference Manuals AAPG – Petroleum Engineering Hand Books: Amyx, Craft, Campbel, etc.

– Log Analysis Books : Batteman, Dewan, Helander etc – Petroleum Reservoir, Stratigraphy and Tectonic Books : …..

Note : Due to the rush preparation of these presentation slides, the sources and references are not noted yet.



PRESENTATION OUTLINEI.

INTRODUCTION

II. WELLSITE GEOLOGYIII.

LOG INTERPRETATION

IV.

WELL TESTING

V. PETROLEUM RESERVOIRENGINEERING

VI.

CORRELATIONS & MAPPING

VII. RESERVES ESTIMATIONVIII.

RESERVOIR SIMULATION

IX.

PLAN OF DEVELOPMENT

X. RESERVOIR MANAGEMENT & PROJECT ECONOMIC



I. INTRODUCTION

1.

COURSE OBJECTIVE

2.

UPSTREAM PETROLEUM INDUSTRY &DEVELOPMENT GEOLOGIST

3. PETROLEUM GEOLOGYa.

SOURCE ROCKS & MATURATION

b.

HYDROCARBON MIGRATION

c.

CAP ROCKS / SEALS

d.

STRUCTURE / TRAP

e.

RESERVOIR ROCKS & FLUID

4.

DRILLING



COURSE OBJECTIVECOURSE OBJECTIVE

•• To introduce participants the generalTo introduce participants the generalpetroleum industrial processes andpetroleum industrial processes and

especially during oil/gas fieldespecially during oil/gas field

development phasedevelopment phase

•• To provide participants the basic ofTo provide participants the basic of

petroleum development/productionpetroleum development/productiongeology as entry provisions intogeology as entry provisions into

upstream petroleum industryupstream petroleum industry

•• Sharing knowledge andSharing knowledge and ““silaturachmisilaturachmi””





PETROLEUM INDUSTRY SECTORSPETROLEUM INDUSTRY SECTORS

Concession Acquiring&

EXPLORATION

DEVELOPMENT&

PRODUCTION

TRANSPORTATION

OIL REFINEMENT /

PROCESSING

UPSTREAMUPSTREAM

DOWNSTREAMDOWNSTREAM

•HIGH RISK•HIGH REWARD•HIGH INVEST.

•LOW RISK•LOW REWARD•HIGH INVEST.

24803

Transporting PetroleumTransporting Petroleum

Oil FieldOil Field

Oil FieldOil Field

PipelinePipeline RefineryRefinery

PipelinePipeline

Railroad Tank CarsRailroad Tank Cars

Mobil

Tank TruckTank Truck

ConsumersConsumers

Industrial Customers

IndustrialCustomers

Local DistributorLocalDistributor

Mobil

TankerTanker

Offshore PlatformOffshorePlatform

24803

Refining PetroleumRefining Petroleum

GasolineGasoline

Fuel GasFuel Gas

Kerosene – Jet FuelKerosene – Jet Fuel

Heating OilHeatingOil

Lubricating OilLubricatingOil

Residual Products– Asphalt, Heavy Fuel Oil

Residual Products– Asphalt,Heavy Fuel Oil

Crude Oil VaporCrude OilVapor

Liquid Crude OilLiquid Crude Oil



EXPLORATION PHASE DEVELOPMENT PHASE

G&G STUDYSEISMIC SURVEY

DRILLINGS

PLAN OF DEVELOPMENT

G&GR STUDYDEV. DRILLING, WORKOVER

PRODUCING, EOR etc.AD’L SEISMIC

MARKETING





PRODUCTON

TIMEEXPLORATION

DEVELOPMENT SECONDARY RECOVERY ABANDONMENT

CONVENTIONAL

Development & Operation GeoscientistsDevelopment & Operation Geoscientists

ExplorationGeoscientists

ExplorationGeoscientists

GeophysicistsGeophysicists



SYNERGIC TEAM N UPSTREAM OIL INDUSTRY

Geologists & Reservoir Engineer

P r o d

u c t i o n

E n g

i n e e r

Surface Prod. Eng.,Processing Eng.,Transportation

Eng. & Marketing

DEVELOPMENT GEOLOGIST

•Reservoir Characterization•Reserves Estimation•Reservoir Optimization



Development Geology = Production Geology = ReservoirGeology

Hybrid discipline: geology on the field and reservoir scale.

Principal Responsibilities of The Development Geologist(DG): Estimation of Volumetric Reserves Justifying drilling & workover options to improve recovery Plan and acquisition geological data while drilling & production Providing a framework for maximum financial return for his

company

DG requires good knowledge of many disciplines : Structural Geology.

Stratigraphy and sedimentology. Reservoir engineering. Drilling methods and engineering. Petrophysics.

Laboratory for rock and fluid Seismology. Petroleum Economics and management.

Petroleum Development Geology



What is a petroleum exploration &

development geologists?EXPLORATION GEOLOGIST DEVELOPMENT GEOLOGIST

DISCOVERS HYDROCARBONRESERVES

Technical and functional expertiseon regional geology

(basin /

petroleum system analysis, tectonicand stratigraphy), geophysical(acquisistion, processing and

interpretation), computer and othertechnical

DEVELOPES & PRODUCESHYDROCARBON

Technical and functional expertiseon reservoir geology, log

interpretation, detailed correlation& mapping of flow unit, basicpetroleum engineering, drilling, field

operation, computer and othertechnical

Additional: Financial awareness –

understanding the business. Project

management, team work, achieving results skills Interpersonal,communication, serving skills



WHY COMPANY SHOULD HAVE A DEVELOPMENT GEOLOGIST

Engineers, Geologists andGeophysicists don’t just specialize in

different fields, they think in differentways.

There is a communication problem:the development geologist must beable to bridge the gap.



Geophysical Processing

E&P Management

DrillingEngineering

ReservoirEngineering

Geoscience

Bridging the Disciplines Enhanced operational efficiencies through new,

multi-disciplinary workflows



responsibility of the DG in

PREDEVELOPMENT EVALUATION

After field discovery :

• Evaluate field forreserves, well

placement anddesign criteria.




DEVELOPMENT DRILLING

DG is responsible for:

– Initiating developmentwell recommendations

– Decide what reservoirgeological data shouldbe collected and preparethe geological prognosis

– Monitoring these wellsduring drilling

– Adjusting developmentplans as wells are drilled




WELL SURVEILLANCE

• Generally handled by the reservoir engineer (RE)

• However, when performance is not as expected or whenremedial work is required (workover, stimulation &optimization) the DG inputs geological constraint.

•RE & DG work together toevaluate unusual reservoirperformance.

•RE & DG then makeremedial recommendations





FIELD STUDIES

One of the most importantroles of the DG :

• Re-evaluation of old fieldsand recognition of newopportunities in these

fields.• This role will become

increasingly important in

the future as reservesdecrease.

• Improved oil recovery as

well as enhance oilrecovery.



CONCLUSION• Development geology is not only a

rewarding, but a lucrative field for thesmall and independent operator.

• In the future, this field (whichrequires skills in many oil/gas fields)will become more important as

reserves decline.• The bottom line in all petroleum

exploitation is financial andeconomic evaluations require input

from many disciplines: the DG musthave these skills.

• The most important ability isRESERVES ESTIMATION andRESERVOIR OPTIMIZATION.



a. SOURCE ROCKS & MATURATIONb. HYDROCARBON MIGRATION

c. CAP ROCKS / SEALS

d. STRUCTURE / TRAP

e. RESERVOIR ROCKS



Petroleum System ProcessesPetroleum System Processes

•• GenerationGeneration -- Burial of source rock to temperature andBurial of source rock to temperature and

pressure regime sufficient to convert organic matter intopressure regime sufficient to convert organic matter into

hydrocarbonhydrocarbon

•• MigrationMigration -- Movement of hydrocarbon out of the sourceMovement of hydrocarbon out of the source

rock toward and into a traprock toward and into a trap

•• AccumulationAccumulation -- A volume of hydrocarbon migrating intoA volume of hydrocarbon migrating intoa trap faster than the trap leaks resulting in ana trap faster than the trap leaks resulting in an

accumulationaccumulation

•• PreservationPreservation -- Hydrocarbon remains in reservoir and isHydrocarbon remains in reservoir and is

not altered by biodegradation ornot altered by biodegradation or ““waterwater--washingwashing””

•• TimingTiming -- Trap forms before and during hydrocarbonTrap forms before and during hydrocarbonmigratingmigrating

P t l S t PP t l S t P



Petroleum System ProcessesPetroleum System Processes

AccumulationAccumulation

SourceSourceRockRock

120° F120° F

350° F350° FGenerationGeneration

MigrationMigration

Seal RockSeal Rock

Reservoi

Rock

Reservoi

Rock

OilOil

WaterWater

Gas CapGasCap

EntrapmentEntrapment





The principal zone of oil formation

during the thermal generation ofpetroleum hydrocarbons

•

If the temperature is too

low, the organic materialcannot transform intohydrocarbon.

• If the temperature is toohigh, the organic materialand hydrocarbons are

destroyed.





• Hydrocarbon migration takes place in two stages:

– Primary migration - from the source rock to a porous rock. This is a

complex process and not fully understood. It is probably limited to afew hundred metres.

– Secondary migration - along the porous rock to the trap. This occurs

by buoyancy, capillary pressure and hydrodynamics through acontinuous water-filled pore system. It can take place over largedistances.

CAP ROCK



CAP ROCK

• A reservoir needs a cap rock.

• Impermeable cap rock keeps the

fluids trapped in the reservoir.• It must have zero permeability.• Some examples are:

– Shales. – Evaporites such as salt or anhyhdrite. – Zero-porosity carbonates.

TRAPSThe reservoir form depends on the



TRAPS

GENERAL

pdepositional environment and post depositionalevents such as foldings and faulting.

The criteria for a structure is that it must have:•Closure, i.e. the fluids are unable toescape.•Be large enough to be economical.

STRUCTURAL TRAPS



•• Tilted faultTilted fault--block trapsblock traps are formed where the upward flow of theare formed where the upward flow of thepetroleum is prevented by impermeability along the fault planepetroleum is prevented by impermeability along the fault planeand by an overlying cap or seal: common in the North Sea.and by an overlying cap or seal: common in the North Sea.

STRUCTURAL TRAPS

Structural traps are formed where the space forStructural traps are formed where the space for

petroleum is limited by a structural featurepetroleum is limited by a structural feature

•• AnticlinalAnticlinal trapstraps areareformed by foldingformed by foldingin the rocks.in the rocks.

•• UnconformityUnconformitytrapstraps areare

generated wheregenerated whereanan erosionalerosional breakbreakin thein the stratigraphicstratigraphicsuccession issuccession isfollowed byfollowed by

impermeableimpermeablestrata.strata.

SALT DOME TRAP



SALT DOME TRAP• Salt Dome traps are caused when "plastic" salt is forced upwards.

• The salt dome pierces through layers and compresses rocksabove. This results in the formation of various traps:

• In domes created by formations pushed up by the salt.

• Along the flanks and below the overhang in porous rock abuttingon the impermeable salt itself.

STRATIGRAPHIC TRAPS



STRATIGRAPHIC TRAPS

StratigraphicStratigraphic

traps are trapstraps are traps

created by thecreated by the

limits of thelimits of the

reservoir rockreservoir rock

itself, withoutitself, without

any structuralany structuralcontrol.control.



PETROLEUM RESERVOIR ROCKSPETROLEUM RESERVOIR ROCKS

DEFINITIONDEFINITION

•• A body of porous and permeable rockA body of porous and permeable rock

containing oil and gas through whichcontaining oil and gas through which

fluid may move toward recoveryfluid may move toward recoveryopening under the pressure existing oropening under the pressure existing or

that may be applied. (that may be applied. (AmyxAmyx, 1960), 1960)



TYPE OF RESERVOIR ROCKS

Sedimentary:

Clastic ; eg. Sandstone, Conglomerate

Non Clastic ; eg. Limestone, Evavorite.

Igneous:Plotunic ; e.g. Granite

Volcanic ; eg. Basalt

Volcanic Clastic : eg Tuff, Breccia.

Metamorphic:

eg. Marble, gneiss, quartzite, slate etc.



Reservoir Rocks

Reservoir rocks need two properties to be successful:

1. Pore spaces able to retain hydrocarbon.

2. Permeability which allows the fluid to move.



DEFINITION OF POROSITY

b

mab

b

p

V

VV

V

VPorosity

−=

POROSITY SANDSTONES



POROSITY SANDSTONES• The porosity of a sandstone depends on the packing arrangement

of its grains.• The system can be examined using spheres.

In a Rhombohedral packing, the pore

space accounts for 26% of the totalvolume.

In practice, the theoretical value is rarelyreached because:

a) the grains are not perfectly round, and

b) the grains are not of uniform size.

With a Cubic packingarrangement, the pore space fills47% of the total volume.



POROSITY AND GRAIN SIZE

• A rock can be made up of small grains or

large grains but have the same porosity.

• Porosity depends on grain packing, not thegrain size.



PORE-SPACE CLASSIFICATION

• Total porosity, φt =

• Effective porosity, φe =

• Very clean sandstones : φt = φe

• Poorly to moderately well -cemented intergranular

materials: φt ≈ φe

• Highly cemented materials and most carbonates:

φe < φt

Volume Bulk

Space PoreTotal

Volume BulkSpace Pore cted Interconne

G S S



DIAGENESIS• The environment can also involve subsequent alterations of the

rock such as:

• Chemical changes.

• Diagenesis is the chemical alteration of a rock after burial. Anexample is the replacement of some of the calcium atoms inlimestone by magnesium to form dolomite.

• Mechanical changes - fracturing in a tectonically-active region.

CARBONATE POROSITY TYPES




Interparticle porosity: Each grain is

separated, giving a similar pore spacearrangement as sandstone.

Intergranular porosity: Pore space iscreated inside the individual grainswhich are interconnected.

Intercrystalline porosity: Produced by

spaces between carbonate crystals.

Mouldic porosity: Pores created by the

dissolution of shells, etc.

• Carbonate porosity is very heterogeneous. It is classified into a

number of types:





Fracture porosity:

• Pore spacing created by thecracking of the rock fabric.

Channel porosity:

• Similar to fracture porositybut larger.

Vuggy porosity:

• Created by the dissolutionof fragments, butunconnected.

CARBONATE POROSITY



CARBONATE POROSITY

• Intergranular porosity is called "primaryporosity".

• Porosity created after deposition is called

"secondary porosity".

• The latter is in two forms: – Fractures

– Vugs.

FRACTURES



FRACTURES

• Fractures are caused when a rigid rock is strained beyond itselastic limit - it cracks.

• The forces causing it to break are in a constant direction,

hence all the fractures are also aligned.• Fractures are an important source of permeability in low

porosity carbonate reservoirs.

VUGS



VUGS

• Vugs are defined as non-connected pore space.

• They do not contribute to the producible fluid total.

• Vugs are caused by the dissolution of solublematerial such as shell fragments after the rock hasbeen formed.

• They usually have irregular shapes.

PERMEABILITY



PERMEABILITY

• The rate of flow of a liquid through aformation depends on:

– The pressure drop. – The viscosity of the fluid.

– The permeability.

• The permeability is a measure of the ease atwhich a fluid can flow through a formation.

• The unit of measurement is the Darcy.• Reservoir permeability is usually quoted in

millidarcies, (md).

DARCY LAW



DARCY LAW

• K = permeability, in Darcies.

• L = length of the section of rock, in centimetres.

• Q = flow rate in centimetres / sec.

• P1, P2 = pressures in bars.

• A = surface area, in cm2.

• µ = viscocity in centipoise.

PERMEABILITY AND ROCKS




In formations with large grains, the permeability ishigh and the flow rate larger.





• In a rock with small grains the permeability is lessand the flow lower.

• Grain size has no bearing on porosity, but has a

large effect on permeability.

ANISOTROPY



ANISOTROPY

Horizontal Permeability

Vertical Permeability

The permeability in the horizontal direction is controlled by thelarge grains.

The permeability in the vertical direction is controlled by the

small grains

1≤ H

V

K

K 1≤

H

V

K

K 1≤

h

V

K

K

CLASTIC



RESERVOIRS

•

Sandstone usually hasregular grains; and isreferred to as agrainstone.

•

Porosity : Determined

mainly by the packing andmixing of grains.

•

Permeability : Determined

mainly by grain size andpacking, connectivity andshale content.

• Fractures may bepresent.

CARBONATE



RESERVOIRS

• Carbonates normally havea very irregular structure.

• Porosity: Determined bythe type of shells, etc. andby depositional and post-

depositional events(fracturing, leaching, etc.).

• Permeability: Determinedby deposition and post-deposition events,fractures.

• Fractures can be very

important in carbonatereservoirs.

LIMESTONES

DOLOMITES



© Schlumberger 1999

DRILLING Christmas

Pipeline toFlow



DRILLING

☯Making a hole or well tomake access intoreservoir and toproduce hydrocarbon(oil & gas) fromsubsurface.

☯ To collect thesubsurface geologicaland reservoirdata/information for

further hydrocarbonexploration as well asdevelopment.

ChristmasTree Process

and

Storage

SurfaceCasing

IntermediateCasing

ProductionCasing

CompletionFluid

CementPacker

Cement

Cement

Tubing

WellFluids

Oil or Gas Zone

Perforations

OIL EXTRACTING HISTORY



OIL EXTRACTING HISTORY

In the earliest day of oilproduction, oil wascollected from surfaceseepages.

Mine shafts were dug tomake a well (like waterwell in Java) to produce

shallow oil.

In the early 19th century

peoples developed cabletool drilling





CABLE TOOLDERRICK



JACK UP UNIT



JACK UP UNIT

A jack-up unit

is a barge with legs that can be

lowered or raised. The barge is towed

to the

drilling location with its legs in the raisedposition. Once in position, the legs are lowered.When they reach the sea-bed, the barge's bodyis hoisted above the water, creating a stable

drilling platform. The length of the legsdetermines the depth of water in which a jack-up barge can be

used. They can generally be

used in up to 100 meters of water. Jack-upbarges are widely employed in the relativelyshallow waters of the North Sea's Southernbasin.



SEMI-SUBMERSIBLE RIG

A semi-submersible drilling rig

is normally a self-

propelled working platform supported by verticalcolumns on submerged pontoons. By varying theamount of ballast water in the pontoons, the unitcan be

raised or lowered in the water.

A semi-submersible vessel is normally held inposition by up to eight very large anchors, or bydynamic positioning: computer controlleddirectional propellers to keep the vessel stationary

relative to the sea-bed, compensating for wind,wave or current.

Semi-submersibles can drill in water depths to 300meters or more all year round.

SETTING UP THE RIG



•

Depending upon the remoteness of thedrill site and its access, equipment may betransported to the site by truck,helicopter or barge.

•

Some rigs are built on ships or barges forwork on inland water where there is nofoundation to support a rig (as in marshesor lakes).

• Once the equipment is at the site, the rigis set up. Here are the major systems ofa land oil rig:

–

Power System

– Mechanical System–

Rotating Equipment

–

Casing

–

Circulation System

–

Derrick

– Blowout Preventer

RIG EQUIPMENT



OWER AND MECHANICAL SYSTEMS

• Mechanical system - drivenby electric motors – hoisting system - used for

lifting heavy loads; consists ofa mechanical winch(drawworks) with a largesteel cable spool, a block-and-tackle pulley and a receivingstorage reel for the cable

– turntable - part of the drillingapparatus

• Power System – large diesel engines - burn

diesel-fuel oil to provide themain source of power – electrical generators -

powered by the diesel enginesto provide electrical power

RIG EQUIPMENT



HE DERRICK

• Derrick - support structure: holdsthe drilling apparatus – tall enough to allow new

sections of drill pipe to beadded to the drilling apparatusas drilling progresses

• Blowout preventers and Rams -high-pressure valves (located

below the rotary table or on thesea floor) – seal the high-pressure drill

lines and relieve pressurewhen necessary to prevent a

blowout (uncontrolled gush ofgas or oil to the surface, oftenassociated with fire)

– Can shut off either the annularspace (between pipe and well)

or the complete hole.

RIG EQUIPMENT



OTATING EQUIPMENT

• Rotating equipment - used for rotarydrilling – swivel - large handle that holds the weight of

the drill string; allows the string to rotate and

makes a pressure-tight seal on the hole – kelly - four- or six-sided pipe that transfers

rotary motion to the turntable and drill string – turntable or rotary table - drives the rotating

motion using power from electric motors – drill string - consists of drill pipe

(connected sections of about 30 ft / 10 m)and drill collars (larger diameter, heavierpipe that fits around the drill pipe and placesweight on the drill bit)

• Drill bit(s) - end of the drill that actually cuts

up the rock; comes in many shapes andmaterials (tungsten carbide steel, diamond)that are specialized for various drilling tasksand rock formations

• Casing - large-diameter concrete pipe thatlines the drill hole, prevents the hole fromcollapsing, and allows drilling mud tocirculate

RIG EQUIPMENT



HE MUD CIRCULATION PROCESS

• There's more to drilling than simplyrotating the bit.

• Fluid is circulated while the drillingproceeds.• Powerful pumps move the fluid down

the pipe, through the bit and back to

the surface, carrying the cuttings andother debris with it.• Thus, on a rotary rig (unlike the cable

tool), drilling can be continuous as

stopping to bail the cuttings is nolonger required.

• The drilling mud also stabilizes thewalls of the hole.

RIG EQUIPMENT IRCULATION SYSTEM



• Circulation system - pumps drillingmud under pressure through the kelly,rotary table, drill pipes and drill collars

– pump - sucks mud from the mud pitsand pumps it to the drilling apparatus

– pipes and hoses - connects pump todrilling apparatus

– mud-return line - returns mud from hole

– shale shaker - shaker/sieve thatseparates rock cuttings from the mud

– shale slide - conveys cuttings to thereserve pit

– reserve pit - collects rock cuttingsseparated from the mud

– mud pits - where drilling mud is mixedand recycled

– mud-mixing hopper - where new mud ismixed and then sent to the mud pits





RIG EQUIPMENT THE

DRILLSTRING

CONTROLLINGTHE WEIGHT ON THE BIT



The weight is held partly bythe hook etc. If not, the drill

bit wouldn’t turn! Collars areadded to the drill string toadd more weight

Hence the driller can controlthe weight on the bit byadding/ removing collars orby raising/lowering theswivel tackle.

TYPE OF BIT - Which bit?



•Largest bit is used first, decreasing with depth•For each formation & depth have a particular set of

jet sizes, gallons per minte, pump strokes per minte,

minimum annular velocity (speed mud returns at tokeep the hole clean), bit hydraulic horsepower.•Hence the hydraulic and bit programs work intandem to most efficiently drill the well giving best

cost per foot, drilling time, minimum down time.

CONTINUING THE DRILLING PROCESS



• Drilling continues in stages: – Drill – run and cement new casings, then drill again.

• When the rock cuttings from the mud reveal the oil sandfrom the reservoir rock, the final depth may have beenreached.

• At this point, the drilling apparatus is removed from thehole and perform several tests to confirm this finding: – Well logging - lowering electrical and gas sensors into the hole

to take measurements of the rock formations – Drill-stem testing - lowering a device into the hole to measure

the pressures, which will reveal whether reservoir rock has beenreached

– Core samples - taking samples of rock to look for characteristicsof reservoir rock





DRILLING PROBLEMS

Other Drilling Problemsther Drilling Problems



WELL COMPLETION TYPE



PRODUCINGSAND

1.1. OpenholeOpenhole CompletionCompletion



pp pp

OpenholeOpenhole completioncompletion

merupakanmerupakan penyelesaianpenyelesaian

sumursumur dimanadimana casingcasingdipasangdipasang hanyahanya sampaisampai didi

atasatas zonazona produktif produktif

(interest zone).(interest zone). JadiJadi sumursumurdiproduksidiproduksi dengandengan kondisikondisi

terbukaterbuka didi sepanjangsepanjang zonazona

produksiproduksi..

CASING SHOE

PACKER

CEMENT

CASING

PRODUCTIONSTRING

P R O D U C I N G

L A Y E R

2. Liner Completion



Ada dua model penyelesaian sumurmenggunakan Liner Completion :

1. Screen Liner Completion

Casing diset sampai di atas zona

produksi yang kemudiandigabungkan dengan kombinasi linerdan screen yang tidak disemen diseluruh permukaan zona produksi

2. Perforated Liner Completion

Metode penyelesaian sumur denganmelakukan pemasangan liner dandisemen pada zona produktif yang

kemudian dilaksanakan pelobangan(perforated) pada zona-zona yangpaling produktif

CASING SHOE

PACKER

CEMENT

CASING

PRODUCTION STRING

LINER HANGER

SLOTTED LINER

LINER SHOE

OIL SAND

P R O

D U C I N G L

A

Y E R

PRODUCTION3. Perforated Casing Completion3. Perforated Casing Completion



Perforated casingcompletion adalah

penyelesaian sumurdengan menutup semuazona produktif denganmenggunakan casingdan disemen kemudiandilakukan perforasi(pelubangan) pada

daerah-daerah produksidi lubang sumur

CASING SHOE

PACKER

CEMENT

CASING

STRING

PERFORATION

OIL SAND

P R O D U C I N G L

A Y E R

g p

PRODUCING WELLCOMPLETION



THE MAST (CHRITMAST-TREE)

Setelah

pemboran

dinyatakan

berhasil

dan

mendapatkan

minyakatau

gas, maka

di

kepala

sumur

dipasang

chritmas

tree yang

didefinisikan

sebagai

rangkaian

dari valve dan fitting yangdigunakan

untuk

control produksi

dan disambungkan dengan bagianatas

tubing head. Pertama

kali

christmas

tree digunakan

untuk

tekanan

aliran

rendah

dan

menengah

dari

suatu

sumur,

dimana

rangkaian

dari

tees,

elbows, nipples, valve yang dibeli

secara terpisah dan dirangkaikan jadi satu di lokasi.



• Wellsite geology is hybrid of



appllied geology on oil and gas welldrilling, its study rock cuttings andwireline logs from oil and gas wellsto determine what rock formationsare being drilled into and how thedrilling should proceed.

• Wellsite Geologist is geologist incharge on data acquisition from oil

and gas well drilling operation.They are required to monitor vitaloperations during the course of thewell, make sure that the wellprogram are carried out perform

formation evaluation activities toensure the well is drilled andevaluated in the most safe, efficientmanner, and cost-effective. Theyalso liaise with drilling engineers,

petroleum engineers and mudlogging geologist during the courseof ro ects. JOB SPIRIT

JOB PORPOSES



TEAM WORK IN RIG SITE1. COMPANY MAN

2. WELLSITE GEOLOGIST

3. DRILLING ENGINEER

4. TOOLPUSHER & RIG CREW

5. MUDLOGGING CREW

6. MUD & CHEMICAL ENGINEER & CREW7. CEMENTING ENGINEER & CREW

8. WIRELOGGING ENGINEER & CREW

9. TESTING ENGINEER & CREW

10. OTHER SERVICES ENGINEERS & CREW11. SUPPORTING CREW

THE RULERSHE RULERS



N RIG SITEN RIG SITECOMPANY MAN

LEADER &DECISION MAKER

DRLG ENG.

•CHEMICAL & CEMENTING•DIRECTIONAL

•WELL COMPLETION

TOOL PUSHER•DRILLING

•RIG MAINTENANCE

GEOLOGIST•MUD LOGGING

•MWD & LOGGING•WIRELINE LOGGING

•CORING

•WELL TESTING

IN SMALL COMPANY

CO. MAN ALSO AS

DRLG. ENG.

WELLSITE GEOLOGIST ENERAL DUTIES & RESPONSIBILITIES1. Supervision of “Formation Evaluation”



contractors (Mud Logging Geologists,MWD Logging Engineers, WirelineLogging Engineers, Coring and WellTesting Personnel)

2. Logistics concerning the formationevaluation contractors and theirequipment

3. All safety aspects for the well andpersonnel during these evaluationoperations

4. Quality control of all evaluation resultsand logs prior to accepting the data orlogs from those contractors

5. Providing relevant correlation and welldata to those contractors during theiroperations

6. Checking all reports and logs from theevaluation contractors prior to sendingthem to oil company offices

WELLSITE GEOLOGIST ENERAL DUTIES & RESPONSIBILITIES



7. Monitoring and supervising thecollecting, processing and dispatchingof formation evaluation samples

8. Safe-guarding the collection, storageand transmission of information andreports at the wellsite

9. Wellsite interpretation of the formation

evaluation data10. Checking and occasionally approving

and signing of service reports andinvoices of the formation evaluation

contractors11. Keeping the drilling superintendent

and operations geologist fullyinformed of all formation evaluation

operations





WELL PROGNOSIS AND ROSPECT DESCRIPTION



Wellsite Geologist should becompletely familiar with all

aspects of the drillingprognosis. Particular attentionshould be paid to any sectionswhich may require geological

decisions.1. Determination of Primary and

Secondary Objectives

2. Determination of Casing Points3. Detection of Overpressured

Intervals

4. Detection of Lost CirculationZones

5. Correlation and Detection of Marker Horizons

6 Determin tion of Geologic B sement or Economic B sement

WELL PROGNOSIS AND ROSPECT DESCRIPTION



6. Determination of Geologic Basement or Economic Basement7. Selection of Logging Run Intervals8. A complete set of correlation logs and reports should be compiled

9. Near by well’s mudlogs, lithlogs and wireline logs should be usedas sources of information

REGIONAL GEOLOGY PREPARATIONFOR WELLSITE GEOLOGIST

to anticipate if it should deviate from the prognosis



to anticipate if it should deviate from the prognosis

• Nature and depth of basement within thebasin

• Geologic age of the section

• Depositional environments and expectedlithologies

• Tectonic setting within the basin

• Formation pressure anomalies• Hydrocarbon occurrences within the basin

• Basin correlations

RIGSITE INFORMATION SOURCES USES

Wireline Logging Unit



Wireline Logging Unit• VSP Used to “look ahead”, formation top confirmation• RFT Fluid sampling, Pressure determination, Oil/Water/Gas

gradients• ResistivityWater Saturation, Porosity, Hydrocarbon evaluation

• Density & Neutron Lithology confirmation, Correlation, Porosity,Overpressure detection, Gas/Oil contacts

• Sonic Porosity, Mechanical properties, Overpressure• Dipmeters Structure, Well trajectory, Facies analysis,

Sedimentology

• Sidewall Cores Biostratigraphy, Geochemistry, Lithologyconfirmation, Hydrocarbon evaluation

Mud-Logging Unit

• Cuttings Geochemistry, Lithology, Correlation, Density, Calcimetry,Hydrocarbons, Shale Factor (C.E.C.), Hole Stability, Bit Condition• Hydrocarbons Total gas, Chromatograph, Gas Ratios, Connection

gases, Trip gases, Oil shows• Gases CO2, H2S

• Engineering Dxc, Torque, Drill Rate, Formation Pressures

RIGSITE INFORMATION SOURCES USES



MWD/FEMWD unit data• Directional Borehole Trajectory (MWD), Dogleg

Severity• Gamma Ray Lithology Determination, Shale

Content,• Resistivity Correlation, Hydrocarbon Evaluation,

Pressure Indication, Sw Estimations• Density Lithology, Correlation, Pressure Indication,Gas/Oil Contact

Others• Coring Biostratigraphy, Reservoir analysis,

Porosity, Permeability

WELLSITE GEOLOGIST RESPONSIBILITIES



IN WIRELINE LOGGING OPERATION

To ensure satisfactory results, the Wellsite

Geologist will be responsible for:

Safety aspects during logging operations

Organizing personnel and equipmentlogistics

Logging Quality Control and Dataaccuracy

Carry out quick look log interpretation and

reporting to operation geologist.

QUICK LOOK LOG ANALYSIS



Existence and depth of known markers.

Top and bottom of each reservoir interval

Gross & net thickness for each reservoirinterval

Type of hydrocarbon and hydrocarbon/watercontacts

Average and range of calculated porosityand water saturation values for each interval

Rw in the clean, water-bearing formations

Propose well test intervals





WELLSITE GEOLOGIST TEAM N MUDLOGGING UNIT

• THE TEAM MUDLOGGING CREW:



• THE TEAM MUDLOGGING CREW:• MUDLOGGING GEOLOGIST (MUDLOGGER)• PRESSURE ENGINEER / DATA ENGINEER• SAMPLE CATCHER

• MUDLOGGING GEOLOGIST – CUTTING & CORE DESCRIPTION, HYDROCARBON SHOW,

POROSITY ETC.

• PRESSURE ENGINEER & DATA – RECORD, MONITOR & ANALYSE THE DRILLING PARAMETERS

SUCH AS ROP, RPM, WOB, TORQUE, – MUD DATA: MUD TANK LEVEL (MUD LOOS & GAIN), MUD

WEIGHT IN/OUT, TEMPERATURE IN/OUT – MUD PUMP DATA : CAPACITY, EFICIENCY, VOLUME IN ETC.

• SAMPLE CATCHER – COLLECT AND PREPARE SAMPLE FOR MUDLOGGING

GEOLOGIST

MUDLOGGING UNIT







TYPE OF SAMPLE



• DRY SAMPLE – obtained from the washed samples collected from the 80-mesh

sieve. A heat source is used for drying purposes.

– Several precautions when drying samples are:• DO NOT oven dry oil-based mud samples• Do not over-dry samples, because they will burn (the burning can be

mistaken for oil staining)• Clay samples should not be oven dried - only air dried

• WET SAMPLE – collected at the shale shaker. Normally the drilling fluid is not

rinsed off.

• GEOCHEMICAL SAMPLE – These samples require special treatment. – A bacteriocide (i.e. Zepharin Chloride) is necessary to prevent the

growth of bacteria which can form additional gas. The samples are

normally sealed at the wellsite, and shipped separately.

CUTTINGS DESCRIPTION

Each lithology should be accurately described and



Each lithology should be accurately described, andthat observations recorded in the following order:

a. Rock Type g. Sorting

b. Classification h. Luster

c. Color i. Cementation/Matrix

d. Hardness/Induration j. Visual Porosity

e. Grain Size k. Accessories/Inclusions

f. Grain Shape l. Oil Show Indications

Usually major oil company has own cutting description manual and its standar legend.

COMPARISON CHARTS FOR VISUAL ESTIMATION OFPERCENTAGE COMPOSITION



PARTICLE SHAPE OUNDNESS VS SPHERICITY



EVALUATION OF HYDROCARBON SHOWS





GAS SHOW• EQUIPMENTS

– chromatograph



– CO2 detection – H2S detection (in exploration & rich sulfur basin)

– total gas detectors that monitor for N, various sulfides andH may also be used

• The amount of gas recorded is dependent upon manyvariables, including;

– Volume of gas per unit volume of formation – Degree of formation flushing – Rate of penetration – Mud Density and Mud Viscosity

– Formation pressure – Gas trap efficiency – Gas detector efficiency – Variability of mud flow rate



GAS SHOW EVALUATION• True Zero Gas :

– The value recorded by the gas detectors when pure air is passed over the detection block

(generally done during calibration). To ensure a stable zero mark, the detectors should be zeroedprior to drilling, at casing points, logging points, etc.



• Background Zero Gas : – The value recorded by the gas detectors when circulating, off-bottom, in a clean, balanced bore

hole. Any gases monitored will be from contaminants in the mud or from gas recycling. This valueis the baseline from which all gas readings are referenced for the striplog and mud log, but not

plotted on the logs. This value will change with respect to changes in the mud system (addingdiesel) and hole size, and should be re-established periodically.

• Background Gas : – This is the gas recorded while drilling through a consistent lithology. Often it will remain constant,

however, in overpressured formations this value may show considerable variation. This is the gasbaseline which is plotted on the striplog and mud log.

• Gas Show : – This is a gas reading that varies in magnitude or composition from the established background. It

is an observed response on the gas detector and requires interpretation as to the cause. Not allgas peaks are from drilled formation, some may occur as post-drilling peaks.

• Connection Gases : – Gas peaks produced by a combination of near-balance/ under-balanced drilling and the removal of

the ECD by stopping the pumps to make a connection. They are often an early indicator of drillingoverpressured formations. These should be noted, but not included as part of a total gas curve.

• Trip Gases : – Gas peaks recorded after circulation has been stopped for a considerable time for either a bit trip

or a wiper trip. As with connection gases, substantial trip gases can indicate a near balancebetween the mud hydrostatic pressure and the formation pressure, they should be recorded but notincluded as part of a total gas curve.

WELL 123



SAMPLE:

MUD LOGGING



SAMPLE:MUD LOGGING





Mud-logging Geologist Corner







WIRELINE LOGIRELINE LOG

1. WHAT IS WELL LOGGING:1. WELL LOG IS A CONTINUOUS RECORD OF MEASUREMENT MADE IN

BORE HOLE RESPOND TO VARIATION IN SOME PHYSICAL



BORE HOLE RESPOND TO VARIATION IN SOME PHYSICALPROPERTIES OF ROCKS THROUGH WHICH THE BORE HOLE ISDRILLED.

2. TRADITIONALLY LOGS ARE DISPLAY ON GIRDED PAPERS SHOWN INFIGURE.

3. NOW A DAYS THE LOG MAY BE TAKEN AS FILMS, IMAGES, AND INDIGITAL FORMAT.

2. WIRELINE LOGGING IS PERFORMED WITH A SONDE LOWERED INTO THEBOREHOLE OR WELL

3. 2 TYPES OF WIRELINE LOGGING :1. OPEN HOLE LOGGING2. CASED HOLE LOGGING

4. INTERPRETATION METHODS1. QUALITATIVE2. QUANTITATIVE

1. MANUAL2. COMPUTERIZED

LOG INTERPRETATIONOG INTERPRETATIONIS A PROCESS OF USING WELL LOGS TO

EVALUATE THE CHARACTERISTIC OFFORMATION :

TOP SAND

LITHOLOGY



• STORAGE CAPACITY porosity,

fluid saturations and net pay thickness • FLUID PROPERTIES density, fluid

type, fluid contacts, API gravity,water resistivity & salinity,

temperature, GOR • GEOLOGICAL SETTING

structural/dip/fracture, geologic environtment, facies characteristic,top/bottom reservoir,

heterogeneities, distribution • PRODUCTIVITY : permeability, water

cut, GOR and rate (estimated)

TOP SAND

SAND THICKNESS

SAND PROSITYPERMEABILITYFLUID SATURATIONS

LOG INTERPRETATIONLOG INTERPRETATIONLog interpretation should provide answers to questions on:



LOG INTERPRETATIONOG INTERPRETATIONIS PART OF RESERVOIR CHARACTERIZATION PROCESS WHICH

SHOULD BE INTEGRATED WITH THE FOLLOWING SURVEYAND ANALYSIS:



– DRILLING OPERATION LOGS:

• CUTTING ANALYSIS, MUD ANALYSIS, DRILLING DATA COLLECTION(PRESSURE, GAS READING, PENETRATION RATE ETC.) ANDANALYSIS.

– CORRING & CORE ANALYSIS :

• SIDE WALL CORE & FULL HOLE CORE

• VISUAL LITHOLOGY DESCRIPTION, HYDROCARBON SHOWS,POROSITY, PERMEABILITY, FORMATION FACTOR, SATURATIONETC.

– PRODUCTIVITY TEST :

• RFT, MDT, DST, PRODUCTION TESTS

– GEOLOGY & GEOPHYSICAL :

• SURFACE GEOLOGY, SEISMIC SURVEY & INTERPRETATION ETC.

RESERVOIR CHARACTERIZATIONESERVOIR CHARACTERIZATION



LOGGING UNITSOGGING UNITS

LOGGING UNIT CONTAINS:• logging cable• winch to raise and lower



winch to raise and lowerthe cable in the well

• self-contained 120-voltAC generator

• set of surface controlpanels

• set of downhole tools

(sondes and cartridges)• digital recording system

Open Hole Logging :

1. The traditional wirelinelogging

2. Logging While Drilling3. Logging on drill pipe

WELLELLLOGGINGOGGING

Logging Job Sequences :



Rig-up logging unit Check Tool and system

Wellsite Geologist (WG) willperform system & tool qualitycontrol

Safety meeting

Tool run in hole

The system is on but never beused for log interpretation

Pull-out and logging WG is the witness, checks the

logging speed and quality.

WG has authority to stop, refuseand re-logging when necessary

Rig-down the logging unit. Print the result WG signs the services ticket

containing type of services andcharges

LOGGING UNIT

SONDE / TOOL

WIRELINE

SAMPLE :SAMPLE : OPEN HOLE LOGOPEN HOLE LOGSP, GR, AIT, SONIC,SP, GR, AIT, SONIC,

DENSITY & NEUTRONDENSITY & NEUTRON



SP

GR DT

AIT

RHOZ

NPHI

1. SP SPONTANEOUS

POTENTIAL LOG2. GR GAMMA RAY LOG3. ELECTRICAL LOG

INDUCTION, LATERAL,SPHERICAL FOCCUSS, MICRO

LATERAL ETC4. NEUTRON LOG CNL, SNP5. DENSITY LOG LDT6. SONIC LOG BHC

7. OTHERS : FMI (DIPMETER &IMAGING), NMRI (NuclearMagnetic Resonance Immaging,TEMPERATURE LOG, CALLIPERLOG, ETC.

S PP

SP results from electriccurrents flowing in the



currents flowing in thedrilling mud.

There are three sources ofthe currents, twoelectrochemical and oneelectrokinetic.

Membrane potential -

largest. Liquid - junction potential.

Streaming potential -

smallest.

SP LOG READINGP LOG READING

• The SSP is thequantity to be



quantity to bedetermined.

• It is the deflectionseen on the SP fromthe Shale Base Line(zero point) to theSand Line (max.deflection)

SP USESP USES

• Differentiate potentially porous andpermeable reservoir rocks from



pimpermeable clays.

• Define bed boundaries, top &bottom of the layer.

• For geological correlation

• Give an indication of shaliness(maximum deflection is clean;minimum is shale).

• Indicate vertical grain size

distribution• Determine Rw (formation water

resistivity) in both salt and freshmuds.

we

mfe

R

Rk SSP log−=

SP scale- + SP DEFLECTIONSP DEFLECTIONS

CORRESPOND TOORRESPOND TO

Rmfmf & Rww VALUESALUES



S H A L E

B A S E

L I N

E



SP BoreholeP Borehole

Effectsffects

• Baseline shifts: These can occur when there are beds

of different salinities separated by a shale which does

not act as a perfect membrane.

SP Surface EffectsP Surface Effects• The SP can be affected by a number of surface effects as it relies on

the fish as its reference electrode.

• Power lines, electric trains, electric welding, close radiotransmitters:



• All these create ground currents which disrupt he "fish“ reference

causing a poor, sometimes useless, log.

GRR Principlesrinciples

• The Gamma Ray log is ameasurement of the formation'snatural radioactivity.



• Gamma ray emission is produced by

three radioactive series found in theEarth's crust. – Potassium (K40) series. – Uranium series.

– Thorium series.• Gamma rays passing through rocks

are slowed and absorbed at a ratewhich depends on the formation

density.• Less dense formations exhibit moreradioactivity than dense formationseven though there may be the samequantities of radioactive material perunit volume.

GR USESR USES• Bed definition top,

bottom, thickness• Shalliness content

and net thickness, The



and net thickness, Theminimum value gives

the clean (100%) shalefree zone, the maximum100% shale zone.

NEUTRON TOOLSNEUTRON TOOLS

• The first neutron tools used a chemical neutron source and



The first neutron tools used a chemical neutron source andemployed a single detector which measured the Gamma Rays

of capture. They were non-directional. The units ofmeasurement were API units where 1000 API units werecalibrated to read 19% in a water-filled limestone. The tool wasbadly affected by the borehole environment.

• The second generation tool was the Sidewall Neutron Porosity(SNP). This was an epithermal device mounted on a pad.

• The current tool is the Compensated Neutron Tool (CNT). Thelatest tool is the Accelerator Porosity Sonde (APS), using anelectronic source for the neutrons and measuring in theepithermal region.

NEUTRONNEUTRON USESUSES



• POROSITY &LITHOLOGYwith density log

• HYROCARBON

INDICATION

The tool measureshydrogen index

DENSITYENSITY• The Density Tools use a chemical gamma ray source

and two or three gamma ray detectors.



g y

• The number of gamma rays returning to the detectordepends on the number of electrons present, the

electron density, ρe.

• The electron density can be related

to the bulk density of the minerals

by a simple equation.

• ρe = ρ( 2Z/A )

Where Z is the number ofelectrons per atom and A is

the atomic weight.

DENSITYENSITY Usesses

• The density tool is extremelyuseful as it has high accuracy



g yand exhibits small borehole

effects.• Major uses include: – Porosity. – Lithology (in combination

with the neutron tool).• Mechanical properties (in

combination with the sonictool).

• Acoustic properties (in

combination with the sonictool).• Gas identification (in

combination with the neutrontool).



SONICONIC OOLOOL The sonic tools create anacoustic signal and measurehow long it takes to pass

through a rock. By simply measuring this time

we get an indication of the



we get an indication of theformation properties.

The amplitude of the signalwill also give informationabout the formation.

SONICONIC -BHCHC

• A simple tool that uses a pair of transmitters and four receiversto compensate for caves and sonde tilt.

• The normal spacing between the transmitters and receivers is3' 5'



3' - 5'.

• It produces a compressional slowness by measuring the firstarrival transit times.

• Used for:

– Correlation.

– Porosity.

– Lithology.

– Seismic tie in /

time-to-depthconversion.

ARRAY SONICRRAY SONIC

• Multi-spacing digital tool.• First to use STC processing.



• Able to measure shear waves

and Stoneley waves in hard

formations.

• Used for:

– Porosity.

– Lithology.

– Seismic tie in /

time-to-depth conversion. – Mechanical properties (from shear and compressional).

– Fracture identification (from shear and Stoneley).

– Permeability (from Stoneley).

Porosity 1orosity 1

• It reacts to primary porosity only, i.e. it does not "see“ the



p y p y y,

fractures or vugs.• The basic equation for sonic porosity is the Wyllie Time

Average:

( ) ma f t t t Δφ1log

ma f

ma

t t

t t

Δ

Δ=

logφ

Porosity 2orosity 2

• Raymer Gardner Hunt.

• This formula tries to take into account some irregularities



• This formula tries to take into account some irregularities

seen in the field.• The basic equation is:

• A simplified version used on the Maxis is:

C is a constant, usually taken as 0.67.

( ) f ma c t t t Δ

+Δ

−=

Δ

φ211

log

log

t

t tC

ma

Δ

Δ=



DETECTINGETECTING

OVERPRESSUREDVERPRESSURED

ZONE WITH THEONE WITH THESONIC LOGONIC LOG

OVERPRESSURED ZONE



LithologyLithology & Porosity& PorosityDeterminationDetermination


Lithology Toolsithology Tools

• Most tools react to lithology - usually in conjunctionwith the porosity



with the porosity.

• Major lithology tools are:

– Neutron - reacts to fluid and matrix.

– Density - reacts to matrix and fluid.

– Sonic - reacts to a mixture of matrix and fluid, complicatedby seeing only primary porosity.

– NGT - identifies shale types and special minerals.

– Geochemical logging, identifies 10 elements; K, U, Th, Al, Si,Ca, S, Fe, Gd, Ti

– From these the exact mineralogy can be computed.

Crossplot Solution

Porosity and



• The plot is a straight line from the matrix point to the 100% porosity,

water point. It is scaled in porosity.

LithologyDetermination

from

Litho-Density* Logand CNL*

(Compensated NeutronLog)

Schlumberger Chart

2.48



12

Porosity 13 %

75% sand & 25% limestone



ELECTRICALELECTRICAL

RESISTIVITY LOGSRESISTIVITY LOGS

Resistivity Theoryesistivity Theory• The resistivity of a substance is a measure of its ability

to impede the flow of electrical current.• Resistivity is the key to hydrocarbon saturation

determination.



Current can only passthrough the water in theformation, hence theresistivity depends on:

– Resistivity of theformation water.

– Amount of water present.

– Pore structure.

determination.

• Porosity gives the volume of fluids but does notindicate which fluid is occupying that pore space.

Resistivityesistivity Modelodel



Smov = Sxo - Sw

NORMAL ToolsORMAL Tools• The voltage measured at M is proportional to the

formation resistivity.• This electrode configuration is the Normal tool.

• The distance between the A and M electrodes.



• The spacing determines the depth of investigationand hence the resistivity being read.

NORMAL and LATERAL ToolsORMAL and LATERAL Tools

• The Lateral device usedthe same principle.

• The difference is in



• The difference is inelectrode configurationand spacing.

• Problems came from "thinbeds" when the signatureof the curve was used to

try and find the trueresistivity.



• This figure shows some of the "signature curves" for theinterpretation of lateral and normal devices in thin beds.

• A library exists plus the rules to extrapolate the measured value to

the true resistivity of the bed.

Laterolog Applicationsaterolog Applications

• Measures Rt.• Standard resistivity in high resistivity

environments.



• Usable in medium-to-high salinity muds.

• Good results in high contrast Rt/Rm.

• Fair vertical resolution (same as porosity tools).

LATEROLOG LIMITS :

•Cannot be used in oil-based muds.•Cannot be used in air-filled holes.•Poor when Rxo > Rt.

MSFL PrincipleSFL Principle

• Uses: – Rxo measurement in

water-based muds.



• This tool uses a set of 5 electrodeswhich focus the signal into the

invaded zone just beyond the mud

cake.

– Correction for deepresistivity tools.

– Sxo determination.

• Limits:

– Rugose hole.

– Oil-based mud. – Heavy or thick mud

cake.



INDUCTION LOGSINDUCTION LOGS


Induction LogsInduction Logs



Induction Principle

UsesIL Uses and LimitsL Uses and Limits

• Measures Rt saturation

• Hydrocarbon content



• Ideal in fresh or oil-basedenvironments.

• Ideal for low resistivity

measurements and when Rxo >Rt.

indications & fluid contacts• Bed definition, lithology,

shalliness

• Correlation• Abnormal pressure

examples 3



• The AIT logs (2' vertical resolution) read correctly in this zone giving a hydrocarbon profile.• The DIL logs are ambiguous as the SFL (electrical log) longer reading shallow because Rxo

is less than Rt

90 Inch investigation(ohmm) 2000.2

0.2

0.2

0.2 2000.0

2000.0

2000.0

0.010000.0

(ohmm)

Cable tension (TENS)(LBF)

(ohmm)

SFL unaveraged (SFLU)

Medium resistivity (ILM)

(ohmm)Deep resistivity (ILD)

10 Inch investigation

(ohmm) 2000.2

20 Inch investigation(ohmm) 2000.2


(ohmm) 2000.2


(ohmm) 2000.2



Saturationaturation• The saturation of a formation represents the amount of a given

fluid present in the pore space.• The porosity logs react to the pore space.

• The resistivity logs react to the fluids in the pore space.

• The combination of the two measurements gives the saturation



g

Matrix

water

oil

Sw = S w irr + Sw "free"

So = S oresidual + So"free"

Resistivity Theoryesistivity Theory• Current can only pass through the water in the

formation, hence the resistivity depends on:

– Resistivity of the formation water.

– Amount of water present.



– Pore structure.

Basics 1asics 1

• F: Formation Resistivity Factor.

F =

R 0

R w



• At constant porosity F is constant.• As porosity increases, Ro decreases and F decreases.

• Experiments have shown that F is inversely proportional to φm

.

• m: is called the "cementation exponent".

• a: is called the "lithology" constant.

F =a

φ m

Basics 2asics 2

• Saturation can be expressed as a ratio of theresistivities:

Sw

n =R 0

R t



where n is the "saturation exponent", an empirical constant.

Substituting for Ro:

Substituting for F:

S wn = FR w

R t

w

n

S =a

φ m

R w

R t

Saturation Equationaturation Equation

w

n

S =a

φ m

R w

R



• The Archie equation is hence very simple. It links porosity andresistivity with the amount of water present, Sw.

• Increasing porosity, φ, will reduce the saturation for the sameRt.

• Increasing Rt for the same porosity will have the same effect.

φt

Invaded Zonenvaded Zone

• The same method can be applied to the invaded zone.The porosity is identical, the lithology is assumed to be



the same, hence the constants a, n, m are the same.

• The changes are the resistivities which are now Rxo andRmf.

• Rmf is measured usually on surface and Rxo ismeasured by the MSFL tool.

• The equation is then: S xon = aR mf

φ m R xo

Ratio Methodatio Method

• Dividing for Sxo and Sw, with n set to 2

S w

S xo

=R xo R t

R mf R w

⎛

⎝ ⎜ ⎞

⎠⎟

1

2



• Observations suggest:

• Hence:

S xo ≈ S w

1

5

S w =R xo R t

R mf R w

⎛ ⎝ ⎜

⎞ ⎠⎟

5

8

Archie parametersrchie parameters

• Rw = resistivity of connate water.

• m = "cementation factor", set to 2 in the simple case.



• n = "saturation exponent", set to 2 in the simple case.• a = constant, set to 1 in the simple case.

All the constants have to be set.

In clastics the values are usually measured for each reservoir.

Values could be

m = 1.8 n = 2, a = 1

An often quoted old formula, the Humble Equation uses:

m = 2.15, n = 2, a = 0.62

Rw determinationw determination

• Rw is an important parameter.



• Sources include: – Formation water analysis

– Local tables / knowledge.

– SP.

– Resistivity plus porosity in water zone.

– RFT sample.

– From Rxo and Rt tools.

Rw from Rwaw from Rwa• If Sw = 1, the saturation equation can become:

R w = φ 2R t



• Assuming simple values for a, m, n.

• Procedure is to:• Compute an Rwa (Rw apparent) using this

relationship.

• Read the lowest value over a porous zone which

• This is the method employed by all computer basedinterpretation systems.

Rw from resistivityw from resistivity

• In a water zone Sw = 1, thus the alternativesaturation equation becomes:



• The value of Rmf is measured;

• Rxo and Rt are measured, the value of Rw can becalculated.

Example of variations in the Archie parameters

Effects of parametersffects of parameters

w

n

S =a

φ m

R w

R t



The following are measurements

POR = 25%, Rt = 5 ohm-m, Rw = .02 ohm-m

Assuming a simple formation witha = 1, m = 2, n = 2

Sw = 25%

Changing n to 2.5, changes the Sw to 33%

Changing m to 3 changes Sw to 50%

Hence the choice of these constants is important



Shaly Sand Evaluationhaly Sand Evaluation


Shaleshales

Clean formation Structural shale

PorosityMatrix Shale



Porosity

Matrix

Porosity

Matrix

Porosity Shale

Matrix

Porosity

Matrix

Laminar shale Dispersed shale

S h a l e

S h a l e

Shale and Logshale and Logs• Shales have properties that have

important influences on log

readings:

• They have porosity.

• The porosity is filled with salted

water



water.• They are often radioactive.

• Resistivity logs exhibit shales aslow resistivity zones.

• Neutron porosity logs exhibitshales as high porosity.

• Density and sonic logs react tothe porosity and matrix changes.

• Gamma ray logs react to shaleradioactivity.

Shale Volumehale Volume• The volume of shale must be computed to

correct the tool readings.• This is achieved using simple equations

such as:



minmax

minlog

GRGR

GRGRV cl

−

−=

minmax

minlog

SPSP

SPSPV cl

−

−=

Shale Volumehale Volume



Shale and Saturationhale and Saturation

• The Archie equation has to be changed totake account of the shale effect.



• The shale looks like low resistivity soanother term is added to the equations.

• The result is an equation which will can beused to compute water saturation in shaly

sands.• All these equations return to Archies

equation if there is no shale present.

Saturation Equationsaturation Equations

•Indonesia Equation

S w =1

V cl

1 −V cl

2

⎛

⎝ ⎜⎜

⎞

⎠⎟⎟

R cl

+φ e

R w

*1

R t



•Nigeria Equation

•Waxman-Smits Equation

•Dual Water Equation

1

R t

=S w

2

F * R w

+BQ v S w

F *

C t =φ t

m S wt

n

a

C w +S wb

S wt

C wb − C w( )⎡

⎣⎢

⎤

⎦⎥

1

R t

=V cl

1 . 4

R cl

+φ e

m2

aR w

⎛

⎝ ⎜

⎞

⎠⎟

2

S w

n

EXAMPLE : PROCESSED LOG

OPEN HOLE LOG

PROCESSED LOG

POROSITY & SATURATIONCALCULATION RESULTS



VOLUMEFLUID

ANALYSIS

SATURATION

DUAL WATER MODEL DEFINITIONSUAL WATER MODEL DEFINITIONS

hydrocarbon

far

water φwf

φhy effective

porosity

φetotal

porosity

= φwf+ φ hy



bound

water

dryclay

clean

matrix

fluids

solids

unitvolume

Vcl

wet clayVdcl

φwb

p yφ t

Clean to Shalelean to Shale

φ t

Matrix Far WaterSAND



φ t

φ t

φ t

Matrix

Matrix

Dry Colloid

Dry Colloid

Bound waterSHALE



Well Test ObjectivesWell Test Objectives1. Identify and Obtain reservoir fluids; oil, gas

& water

2. Determine basic reservoir parametes;



2. Determine basic reservoir parametes;productivity (PI), permeability(k), skin (S),initial Resv. Pressure (P*) & Resv. Temp.

3. Well potential & deliverability (gas well) : Itmay be mandatory to proof field

commerciality4. Boundary & irregular conditions Reservoir

(GOC, OWC & Reservoir Limit)

WELL TESTING METHODSWELL TESTING METHODS

• HOLE CONDITION:

– OPEN HOLE

– CASED HOLE



C S O

• TOOLS RUN IN HOLE : – WIRELINE TESTING : RFT, MDT & DST (IT WAS)

– PRODUCTION TEST WITH COMPLETION STRING

IN PLACE : DST

Surface Test Equipment

WELL TESTING SCHEMATICat

Cased Hole



Downhole TestEquipment & Tool

DST & TCP

Subsea SafetyEquipment

DOWNHOLE TESTING EQUIPMENT

Open-Hole Sampling EquipmentRDT & RCI are equivalent with RFT/MDT

Formation Test Tool (FTT) samplechambers hold 420cc to 3 gallons of

reservoir fluid depending on make andmodel.

Open hole samples aid production and



Baker RCI®

Halliburton RDT®

p p pfacility designs and are sometimes used

for PVT studies.

1ST GENERATION

RFTREPEATED FORMATION TESTER

- unlimited pressure survey

- 1 to 2 fluid sampling



2ND GENERATION

MDTMODULAR FORMATION DINAMIC

TESTER

- unlimited pressure survey

- many fluid sampling (unlimited?)

- able to identify fluid type

- able to replace(pump out)unrequired fluid sample

SCHLUMBERGER



DOWNHOLE TESTING

EQUIPMENT

RFT / MDT

Mud pressure



Reservoir pressure

Build-up pressure

Example RFT Record

Wireline pen Hole Testing FT/MDT/RDT/RCI/etc.

• To identify the reservoirpressure

• To identify the fluid content



o de t y t e u d co te t

• To estimate the permeability

• To estimate the productifity

• To define the fluid contact (OWC,OGC and GWC if any)

Fluid Contact Determinationwith fluid gradient from RFT

W a t e r G

r a d i e

n t 0 . 4 3 3 h

O

i l G r a d i e n t 0

. 3 6

7 p s i / f



oil

water

RFT depth

3 p s i / f t

pressure

d e p t h f t

OWC



Performing Well Test ith DST

• Clean up (flow)• Shut-in

• Main flow (one period or

flow-after-flow, flowingtest with 4 to 5 different



test with 4 to 5 differentchoke size)

• Main Build –up (shut-in)

Selective Layer Testing

17 1/2”

26” 20 ft @ 500’



8 1/2” 7” @ 17690’

12 1/4”

9 5/8” @ 15500’

Layer B

Layer A

Example :

TEST STRING



DST & TCP



Well Productivity

AOFP = 344 MMscf/d

CGR = 24.5 STB/MMscf/d

IPR plot3500



Tested gas and condensate rates can beincreased to 125 MMscf/D and 3100 BPD

2.5E+550000

1500

1.5E+5 3.5E+52.5E+5

Gas Rate, Mscf/d

P r e s s u r e , p s i

Testing Risk Factors

Layers communication due topoor cement bond

High pressure and temperatures(over 350°F)



(over 350 F)

Pressure and fluid loss through

packers Annulus-tubing fluid

communication

Water coning or sanding Layers crossflow

THE ROLE of WELLSITE/DEVELOPMENT GEOLOGIST (DG) in WELL TESTING

OPEN HOLE TESTINGwith RFT/MDT

CASED HOLE TESTINGwith DST

DG Propose/selects the testing/perforation sand, interval and depth

Estimate the reservoir fluid contents and it’s static pressure

Provide the reservoir rock parameter for testing analysis such as lithology porosity



Provide the reservoir rock parameter for testing analysis such as lithology, porosityand permeability if any (from log, or qualitative)

Stop the testing when unsafe operation Testing Engineer (TE) decision

Decide testing duration TE decide flow & shut-in periods. TE alsoselects choke size for flow testing.

Select taken fluid sample TE decide fluid sampling methods. Andresponsible for fluid sample handling

As Operation Witness will validate &analyse the result

TE is prime Operation Witness and willvalidate & analyse the testing result.

DG & TE will be along selecting theperforation method

PERFORATION1. THROUGH CASING GUN

Hyperjet/HSD(high shot density)

2. THROUGH TUBING GUN Enerjet

3. TCP (Tubing Conveyed Perforation)





GUN TYPES



DG and/or Wellsite eologist Responsibilities n Perforation Job

1. Define the perforation intervals atporous zone & hydrocarbon zone(pay zone.

2. Evaluate and prepare the perforationdesign such as gun type, size, SPF( h t ft) S i ( l b t

PERF. At Net pay



(shot per ft), Spacing (angle betweentwo shots), charge/explosive type;

penetration deep and entrance hole.3. Perforation environment (fluid type

in the hole); using mud or brinewater or special completion fluid,

under/over balance.4. Witness the gun loading, correlation,

shooting result (whether all chargesexploded or not) “SAFETY FIRST”





THE RESERVOIRTHE RESERVOIR



PETROLEUMPETROLEUMRESERVOIRRESERVOIR

• ROCK PROPERTIES

• FLUID PROPERTIES



U O S

• PRESSURE

• RESERVOIR DRIVE

ROCK PROPERTIESROCK PROPERTIES

Rocks are described by three properties:

– Porosity - quantity of pore space

– Permeability - ability of a formation to flow



– Matrix - major constituent of the rock

note: porosity & permeability has been discussed partially in

“Chapter I. Introduction”

• Permeability is a property of the porous medium and is a

measure of the capacity of the medium to transmit fluids

• Absolute Perm: When the medium is completelysaturated with one fluid, then the permeability

measurement is often referred to as specific or absolutepermeability

PERMEABILITY PERMEABILITY



• Effective Perm: When the rock pore spaces contain

more than one fluid, then the permeability to a particularfluid is called the effective permeability. Effectivepermeability is a measure of the fluid conductancecapacity of a porous medium to a particular fluid when

the medium is saturated with more than one fluid• Relative Perm: Defined as the ratio of the effective

permeability to a fluid at a given saturation to theeffective permeability to that fluid at 100% saturation.

DARCY DARCY ’’S LAW S LAW

q

Direction of flow A

p2 p1L



L = lengthq = flow rate

p1, p2 = pressures

A = area perpendicular to flow

μ

= viscosity

)( 21 p p L

Aq k

−•=

k = permeability(measured in darcies)

k/ μ =

kh/ =

DARCY DARCY ’’S LAW:S LAW: RADIAL FLOW RADIAL FLOW

. rrw



h = height of the cylinder (zone)

P = pressure at r

Pw = pressure at the wellbore

rw / rln ) Pw P( khq

μ−= 2

PERMEABILITY PERMEABILITY –– POROSITY POROSITY

CROSSPLOTCROSSPLOT

100

10

10

100

1000

t y ( m d )

Limestone A1 Sandstone A1



1

0.1

0.01 0.01

0.1

1

10

2 6 10 14 2 6 10 14 18

P e r m e a b i l i

Porosity (%)

• Oil

k

kk eo

ro =

k

CALCULATING RELATIVECALCULATING RELATIVE

PERMEABILITIESPERMEABILITIES



• Water

• Gas

k

k

kew

rw =

kkk

egrg =

Relative Permeability Curveelative Permeability Curve



IRREDUCIBLE WATER SATURATIONRREDUCIBLE WATER SATURATION• In a formation the minimum saturation induced by

displacement is where the wetting phase becomesdiscontinuous.

• In normal water-wet rocks, this is the irreducible water

saturation, Swirr.• Large grained rocks have a low irreducible water

saturation compared to small-grained formations



saturation compared to small-grained formationsbecause the

capillary

pressure is

smaller.

TRANSITION ZONERANSITION ZONE• The phenomenon of capillary pressure gives rise to the

transition zone in a reservoir between the water zone and theoil zone.

• The rock can be thought of as a bundle of capillary tubes.

• The length of the zone depends on the pore size and the

density difference between the two fluids.



Relativeelative

Permeabilityermeability

• Take a core 100% water-saturated. (A)

• Force oil into the coreuntil irreducible watersaturation is attained

(Swirr). (A-> C -> D)• Reverse the process:

force water into the core



force water into the coreuntil the residualsaturation is attained. (B)

• During the process,measure the relativepermeabilities to waterand oil.

FLUID SATURATIONSLUID SATURATIONS• Basic concepts of hydrocarbon accumulation

– Initially, pore space filled 100% with water

– Hydrocarbons migrate up dip into traps – Hydrocarbons distributed by capillary forces and gravity – Connate water saturation remains in hydrocarbon zone

• Fluid saturation is defined as the fraction of pore volumeoccupied by a given fluid



• Definitions

Sw = water saturationSo = oil saturationSg = gas saturationSh = hydrocarbon saturation = So + Sg

• Saturations are expressed as percentages or fractions, e.g. – Water saturation of 75% in a reservoir with porosity of 20%

contains water equivalent to 15% of its volume.

SATURATIONATURATION

• Amount of water per unit volume = φ

Sw

• Amount of hydrocarbon per unit volume = φ

(1 - Sw) =

φ

Sh

(1 S )



φ

Matrix1 − φ

Water

Hydrocarbon (1-Sw)

φ Sw

RESERVOIR PRESSUREESERVOIR PRESSURE

• Lithostatic pressure is caused by thepressure of rock, transmitted by grain-to-grain contact.

• Fluid pressure is caused by weight ofl f fl id i h



column of fluids in the pore spaces.Average = 0.465 psi/ft (saline water).

• Overburden pressure is the sum of thelithostatic and fluid pressures.

RESERVOIR PRESSUREESERVOIR PRESSURE• Reservoir Pressures are normally controlled by the

gradient in the aquifer.

• High pressures exist in some reservoirs.





RESERVOIR TEMPERATURE GRADIENTESERVOIR TEMPERATURE GRADIENT



The chart shows three possible temperature gradients. Thetemperature can be determined if the depth is known.

High temperatures exist in some places. Local knowledge is important.

FLUIDS IN A RESERVOIRLUIDS IN A RESERVOIR• A reservoir normally contains either water or

hydrocarbon or a mixture.• The hydrocarbon may be in the form of oil or

gas.

• The specific hydrocarbon produced dependsth i d t t



on the reservoir pressure and temperature.

• The formation water may be fresh or salty.

• The amount and type of fluid produceddepends on the initial reservoir pressure,rock properties and the drive mechanism.

HYDROCARBON COMPOSITIONYDROCARBON COMPOSITION

• Typical hydrocarbons have the following composition in Mol Fraction

• Hydrocarbon C1 C2 C3 C4 C5 C6+

• Dry gas .88 .045 .045 .01 .01 .01

• Condensate .72 .08 .04 .04 .04 .08

• Volatile oil 6- 65 08 05 04 03 15- 2



• Volatile oil .6-.65 .08 .05 .04 .03 .15-.2

• Black oil .41 .03 .05 .05 .04 .42

• Heavy oil .11 .03 .01 .01 .04 .8

• Tar/bitumen 1.0

• The 'C' numbers indicated the number of carbon atoms in the molecular chain.

HYDROCARBON STRUCTUREYDROCARBON STRUCTURE

• The majorconstituent ofhydrocarbons is

paraffin.



HYDROCARBON CLASSIFICATIONYDROCARBON CLASSIFICATION

• Hydrocarbons are also defined by their weight and the Gas/Oil ratio. Thetable gives some typical values:

GOR API Gravity

• Wet gas 100mcf/b 50-70



• Condensate 5-100mcf/b 50-70

• Volatile oil 3000cf/b 40-50

• Black oil 100-2500cf/b 30-40

• Heavy oil 0 10-30

• Tar/bitumen 0 <10



FLUID PHASESLUID PHASES

• A fluid phase is a physically distinct state, e.g.: gas oroil.

• In a reservoir oil and gas exist together at equilibrium,

depending on the pressure and temperature.

• The behaviour of a reservoir fluid is analyzed using the



y g

properties; Pressure, Temperature and Volume (PVT).• There are two simple ways of showing this:

– Pressure against temperature keeping the volume constant.

– Pressure against volume keeping the temperature constant.

PVT ExperimentVT Experiment



PHASE DIAGRAM SINGLE COMPONENTHASE DIAGRAM SINGLE COMPONENT• The experiment is conducted at different temperatures.

• The final plot of Pressure against Temperature is made.

• The Vapour Pressure Curve represents the Bubble Pointand Dew Point.

• (For a single component they coincide.)



THE FIVE

RESERVOIR

FLUIDS

Black Oil

Criticalpoint

P r e s s u r e , p s i a

B u b b

l e p o i n

t l i n e

Separator

Pressure pathin reservoir

Dewpoint line

9 0

8 0

9 0

7 0

6 0

5 0

4 0

1 0

3

0

2 0

% Liquid

Temperature, °F

P r e s s u r e

Temperature

Separator

% Liquid

B u b b l

e p o i n t

l i n e

D e w p o i n

t l i n e

Dewpoint line

Volatile oil


3

2

1

5

1 0

3

3 0

2 0

4 0 5 0

6 0

7 0

8 0

9 0

Criticalpoint

Black Oil Volatile Oil



3

3 0 2 0

1 5

1 0

4 0

Separator

% Liquid


1

2Retrograde gas

Criticalpoint

B u b b

l e p o

i n t l i n

e

D e w

p o i n t l i n

e

5

0

P r e s s u r e

Temperature

P r e s s u r e

Temperature

% Liquid

2

1

Pressure path

in reservoir

Wet gas

Critical

point

B u b b l e p o i n

t

l i n e

Separator

1 5 2 5 3 0

D e w p o i n

t l i n

e

P r e s s u r e

Temperature

% Liquid

2

1

Pressure path

in reservoir

Dry gas

Separator 2 5

D e w p o i n

t l i n

e

1 5 0

Retrograde Gas Wet Gas Dry Gas



FIELD IDENTIFICATION

BlackOil

VolatileOil

RetrogradeGas

WetGas

DryGas

Initial

ProducingGas/LiquidRatio, scf/STB

<1750 1750 to

3200

> 3200 > 15,000* 100,000*

Initial Stock- < 45 > 40 > 40 Up to 70 No



Tank LiquidGravity, °API

p

Liquid

Color of Stock-Tank Liquid

Dark Colored LightlyColored

WaterWhite

NoLiquid

*For Engineering Purposes

LABORATORY ANALYSIS

BlackOil

VolatileOil

RetrogradeGas

WetGas

DryGas

PhaseChange inReservoir

Bubblepoint Bubblepoint Dewpoint NoPhase

Change

NoPhase

ChangeHeptanesPlus, MolePercent

> 20% 20 to 12.5 < 12.5 < 4* < 0.8*



Percent

OilFormationVolumeFactor at

Bubblepoint

< 2.0 > 2.0 - - -

*For Engineering Purposes

PRIMARY PRODUCTION TRENDS

G O R

G O R

G O R

G O R

G O R

Time Time TimeTimeTime

Noliquid

DryGas

WetGas

RetrogradeGas

VolatileOil

BlackOil



TimeTimeTimeTimeTime

No

liquid° A P I

° A P I

° A P I

° A P I

° A P I

BLACK OIL FLUID PROPERTIES



Sample : DRY GAS FLUID PROPERTIS



FVF ormationVolume Factor

• Fluids at bottom holeconditions producedifferent fluids atsurface:

• Oil becomes oil plusgas.

• Gas usually stays as



gas unless it is aCondensate.

• Water stays as waterwith occasionally

some dissolved gas.

FLUID VISCOSITY







Water Invasion• Water invading an oil zone, moves

close to the grain surface, pushingthe oil out of its way in a piston-

like fashion.

• The capillary pressure gradientforces water to move ahead fasterin the smaller pore channels.

• The remaining thread of



oil becomes smaller.• It finally breaks into smaller

pieces.

• As a result, some dropsof oil are left behind in

the channel.

Water DriveOil producing well

Oil Zone



• Water moves up to fill the "space"

vacated by the oil as it is produced.

Water Water

Cross Section



Water Drive 2



• This type of drive usually keeps the reservoir pressure fairlyconstant.

• After the initial “dry” oil production, water may be produced. Theamount of produced water increases as the volume of oil in thereservoir decreases.

• Dissolved gas in the oil is released to form produced gas.



Gas Cap Drive



Gas from the gas cap expands to fill the spacevacated by the produced oil.

Gas Cap Drive 2

• As oil production declines, gas production increases.

• Rapid pressure drop at the start of production.





Solution Gas Drive 2

• An initial high oil production is followed by a rapid decline.

• The Gas/Oil ratio has a peak corresponding to the higherpermeability to gas.

• The reservoir pressure exhibits a fast decline.



GRAVITY DRAINAGE

Oil

Oil

Point C

Gas

Gas

Gas



Oil

Point A

Point B

Recovery = to 60% of OOIP

Drives General

• A water drive can recover up to 60% of the oil in place.• A gas cap drive can recover only 40% with a greater

reduction in pressure.

• A solution gas drive has a low recovery.



5

4

3

2 i l r a

t i o ,

M S C

F / S

T B

Gas-cap drive

Solution-

gas drive

Gas/oil Ratio Trends



1

0

Cumulative oil produced, percent of original oil in place

0 20 40 60 80 100

G a s / o

Water drive



Drive ProblemsWater Drive:• Water can cone upwards and be

produced through the lowerperforations.

Gas Cap Drive:• Gas can cone downwards and be

produced through the upperperforations.

Pressure is rapidly lost as the gas



• Pressure is rapidly lost as the gasexpands.

Gas Solution Drive:• Gas production can occur in the

reservoir, skin damage.

• Very short-lived.



Secondary Recovery • Secondary recovery covers a range of techniques used to

augment the natural drive of a reservoir or boost production ata later stage in the life of a reservoir.

• A field often needs enhanced oil recovery (EOR) techniques tomaximise its production.

• Common recovery methods are: – Water injection.

– Gas injection.

I diffi lt i h th t i i h il



• In difficult reservoirs, such as those containing heavy oil, moreadvanced recovery methods are used:

– Steam flood.

– Polymer injection. . – CO2 injection.

– In-situ combustion.





• To demonstrate reservoirproperties in a plan view

projection with objectives topromote optimal fielddevelopment.

• The maps will be used forwell placement, reservescalculation, reservoirperformance monitoring.



• Mapping is part of reservoircharacterization, thereforethe results of which very

depend on the expert’sworking knowledge inapplied geologic models

WELL PLACEMENT



• TOP/SURFACE MAPS : – Structure Map

– Fault Map

– Unconformity Map

• THICKNESS MAPS : – Isopachous Map Gross & Net

• OTHERS & COMBINED MAPS :

Carried out by DG



• OTHERS & COMBINED MAPS : – Isoporosity Map - Isopermeability Map

– Pressure Map - Saturation Map

– Productivity Map - Shale Map

– Net to Gross Sand Map - Etc.

MAPPINGMAPPING

CONCEPTUAL WORKFLOWCONCEPTUAL WORKFLOW

1. GEOLOGIC MODEL1. FACIES2. STRATIFICATION3. CONTINUITY

4. TRENDS5. TECTONIC

2. GEOLOGICAL MAP1. STRUCTURE2. ISOPACH

3. FAULTS/BARIER

SEISMIC

WELL LOGS

CORE & CUTTING

ANALYSIS

INTERPRETATION,ZONATION,

INTEGRATION,CORRELATION,

ANALYSIS&

D A T A PROCESING

PROCESSING PRODUCTS

REGIONALGEOLOGY



4. UNCONFORMITY

3. RESERVOIR MAP1. NET PAY

2. POROSITY3. PERMEABILITY4. PRESSURE5. PRODUCTIVITY

S S

WELL TESTS &PRESSURE

FLUID ANALYSIS

PRODUCTIONDATA

S S&

DEFINE VALUES

BASIC KNOWLEDGEBASIC KNOWLEDGE

FOR RESERVOIR CORRELATION & MAPPINGFOR RESERVOIR CORRELATION & MAPPING

• LOG ANALYSIS (electro-facies, reservoir parameters,stratigraphy, structure, etc.)

• SEISMIC INTERPRETATION (structure, reservoircontinuity, hydrocarbon indications)

• SEDIMENTARY FACIES, DEPOSITIONALENVIRONMENTS & SEQUENCE STRATIGRAPHY

• MODELS OF BASINS & RESERVOIRS, AND ALSOREGIONAL GEOLOGY OF THE MAPPED FIELDtrends of sedimentation & major tectonic and it’sramifications



trends of sedimentation & major tectonic and it sramifications

• BASIC RESERVOIR ENGINEERING pressure regime,models, fluid propertie and production performance.

• BASIC COORDINATE SYSTEMS/GEOMETRY &STEREOMETRY base map, well trajectory, leaseboundary etc.

LOG ANALYSISFOR RESERVOIR CORRELATION & MAPPING

• LITHOLOGY / FACIES IDENTIFICATIONS &MARKERS DETERMINATION continuity, consistency,missing sections & repetition sections (faults or overturn)

• DEPOSITIONAL ENVIRONMENT

• VERTICAL ZONATIONS

– TOP & BOTTOM



– FLOW UNIT

• FLUID CONTACTS OWC, GOC & GWC

• RESERVOIR PARAMETERS Por, Perm, Sw etc

• NET PAY THICKNESS DETERMINATIONS









FMI fulbore formation micro imagerRAB resistivity at the bit



SEISMIC FOR RESERVOIR GEOLOGY

• Aid in : – Reservoir facies mapping reservoir distribution : lithology,

isopach etc 3D – Reservoir properties mapping porosity – Locating / define fluid contacts

– Monitoring fluid fronts 4D – Sructure & stratigraphic interpretations

• Seismic methods : – 2D Seismic



– 3D seismic – VSP – Well to well seismic – Time-lapse seismic monitoring etc.

EXPLOSIVE

LAPISAN BATUAN



LAPISAN BATUAN



VSPV S P(Vertical Seismic Profiling)



SLB, OFR, 2007 Autumn

Example :

Comparison of VSP & Seismic Results



SLB, OFR, 2007 Autumn

SURFACE SEISMIC IMAGESURFACE SEISMIC IMAGE

TIES WITH VSP

3D Seismic



Basic of 4D Seismic



Example : 4D Seismic uses



DEPOSITIONAL ENVIRONMENTSDEPOSITIONAL ENVIRONMENTS

AND SEDIMENTARY FACIESAND SEDIMENTARY FACIES





Distinctive and Common SedimentaryDistinctive and Common Sedimentary

Facies AssociationsFacies Associations

Vertical successionsprincipally identifiedby lithology,associations and

vertical arrangementof sedimentarystructures indicative ofparticularsedimentarydepositional



depositionalenvironments



CARBONATE DEPOSITIONAL ENVIRONMENTS

(DIAGRAM BY R.G. LOUCKS AND C.R. HANDFORD, UNPUBLISHED)

SEQUENCE STRATIGRAPHY CONCEPTSSEQUENCE STRATIGRAPHY CONCEPTS• Sequence stratigraphy highlights the role of allogenic controls on

patterns of deposition, as opposed to autogenic controls thatoperate w ithin depositional environments

– Eustasy (sea level)

– Subsidence (basin tectonics)

– Sediment supply (climate and hinterland tectonics)



COMPONENTS OF SEQUENCES



SLB, OFR, JAN93



GROSS NET NET PAY





LEVELS OFRESERVOIRHETEROGENETY

(fluviatil rock)









Schematic Reservoir Layering Profile

in a Carbonate ReservoirBaffles/barriers

3150

SA -97A SA -251 SA -356 SA -71 SA -344 SA -371 SA -348 SA -346 SA -37

3200

3250

3300

3100

3150

3250

3300

3250

3150

3200

3100

3150

3200

3200

3250

3250

3150

3200

3250

3100

3200

3150

3200

3250

Flow unit



33503250

3350

3300

3300

3250

3300

3350

From Bastian and others

E

• BASED ON :

– PRODUCTION TESTINGS the most

reliable methods

– LOGS (electrical logs combined with FDC &

CNL)

PRESSURE SURVEY pressure gradient



– PRESSURE SURVEY pressure gradient

from RFT – SEISMIC hydrocarbon indications







CORRELATIONSCORRELATIONS

• “Reservoir Correlation” is part of pre-mapping worksof reservoir to locate and trace the lateraldistribution, continuity, geometry of reservoirs and

it’s flow unit.

• Correlation should be carried out based all theavailable data, a sedimentological and stratigraphic

model of the reservoirs.• Some pre-correlation works notes:

– Wireline log will be the basic data and will be calibrated andintegrated with other data analysis results such as core

analysis especially. – Vertical profile analysis of well data should be carried out

previously to establish the facies, sequences and



p y , qsedimentary environment.

– Zonation of lithology and flow unit, and also markerinentifications should be geologically sound. – Define the zone top & bottom, zone thickness (gross & net)

etc.

Tips for Correlation

• Stratigraphic Cross Section is the best demonstration of acorrelation results.

• The section should show reservoir lateral and vertical facieschanges, markers continuity, missing & repetition sections,completion & prod. testing notes, etc.

• Good markers can be organic shale, coal/lignite, limestone beds,

glauconite, siderite etc. which has good continuity andcorrespond to the geologic events such as maximum flooding,emmergence etc.

• Start the correlation with the whole log section of individual well,make zonation based on electro facies then define all markersand zones of interest. Indicates any missing and repetitionsection. Then carry out a detail correlation of objective reservoirs.

• For reservoir connectivity indication use also fluid contents and



• For reservoir connectivity indication use also fluid contents andcontacts, pressure data and production performance data

• Prepare a good tabulation (database) of geologic data such asdepth of top & bottom of reservoir, net & gross thickness, fault’sdepth etc.

CORRELATION

PROBABILISTIC to DETERMINISTIC





After EA Arief S, IPA, 2001



B

C

D

LATIHAN



A

LATIHAN

OIL

OIL OWCA

C

B

D

WELL #123

WELL #456



C



LATIHAN

OIL

OIL OWCA

C

B

D

WELL #123

WELL #456



C



Tip for Reservoir Mapping

• Prepare a good base-map based on coordinates ofwells and seismic shot points (line & BM).

• Plot the data accurately then start contouring fromthe highest positions for structure and refer toseismic maps.

• Stucture contour should be stop whenevercross/meet the fault plane. Consider the faultthrows and missing/repetition sections for the next

blocks contouring.• For isopach maps initiate with facies map

construction then followed with isopach contouring



construction then followed with isopach contouring.

• Understand the contouring principles such as nocrossing contour etc.

-

1 0 0 0 ’

- 1 1

0 0 ’

- 1 2 0 0

’ - 1 3 0 0 ’

- 1 2 0 0 ’

- 1 1 0 0 ’

- 1 0 0 0 ’

- 1 0 0

0 ’

- 1 1

0 0 ’

- 1 2 0 0 ’

- 1 1 0

0 ’

- 1 0 0 0

’

- 1 2 0 0 ’

- 1 2 0 0 ’

- 1 0 0 0

’

- 1 1 0

0 ’

- 1 2 0

0 ’

- 1 1 0

0 ’

- 1 0 0 0

’

1 0 ’

2 0 ’

2 0 ’ 1 0

’ 0 ’

2 0 ’

1 0 ’

0 ’

2 0 ’

3 0 ’

3 0 ’

2 0 ’



0 ’ 0 ’

1 0 ’



-1 0 0 0 ’

-11 0 0 ’

-1 2 0 0 ’

-1 3 0 0 ’

-1 4 0 0 ’

-1500 ’

-1600’

-1700’

-1600 ’

-1 5 0 0 ’

- 1 4 0 0 ’

- 1 3 0 0 ’

PLAN VIEW

SECTION VIEW



-1 700’

- 1 7 0 0 ’

- 1 6 0 0 ’

- 1 5 0 0 ’

- 1 4 0 0 ’

- 1 3 0 0 ’

- 1 2 0 0 ’

- 1 1 0 0 ’

- 1 0 0 0 ’







100010 10

102010 3 0

1040

NET PAY MAP CONSTRUCTION

STRUCTURE MAP

C



1050

Contour unit in meter sub-sea

Contour interval 10 mOWC @ 1050

mss

0

5 m

1 0 m

1 5 m


ISOPACHOUS MAP

C t it i t15 m



1 0 m

5 m

0 m

Contour unit in meter

Contour interval 5 m

0 m

5 m

1 0 m

1 5 m


NET PAY MAP

1 51 0

5 C t it i t

10 10

1020

10 3 0

1040

1050



1 0 m

5 m

0 m

5 0



d o w n

FAULT MAP



SURFACES OF FAULTS X AND Y

WEST-EAST CROSS SECTION

A S a

n dA S a n d

B S

a n d

B S a n d

B

U N C O N F O R

M I T Y



STRUCTURE MAP OF A SAND



ISOPACHOUS MAP OF A SAND



NET PAY MAP OF A SAND



STRUCTURE MAP OF B SAND



ISOPACHOUS MAP of B SAND



NET PAY MAP OF B SAND

NET GAS

NET OIL



FAULT ANALYSISSEALING OR NON SEALING

• Can be based on : – Log analysis

– Well test data

– Pressure build-up analysis – Interference test

– Production data

– Using radioactive tracer

– Core & Rock Cutting



– Correlation & Sratigraphic analysis





ALLAN DIAGRAM



Disagregated& cemented

Phillosillicate-smear

framework

clay-smearfault rocks



A

B

A

B

C

C

D

D

E

E

F



Allan Diagram for non-sealing fault

DOWN BLOCK

UP BLOCK

DOWN BLOCK

UP BLOCK

Common Oil Water Contacts

OIL

OILOIL

OIL

WATER

WATER





0 m

5 m

1 0 m

1 5 m

1 0 m


NET PAY MAP

1 51 0

5 0


10 10

1020

10 3 0

10401050



5 m

0 m






• The most important role of a DG is to:

– estimate the oil and gas reserves that may

be discovered in a particular venture.

– keep track of the reserves in all pastventures.



THE 4 BASIC RESERVES ESTIMATION ETHODS

1. Educated Guess and/or Comparisonwith nearby production.

2. Static Reserves Estimates Volumetric Calculations

3. Dynamic Reserves Estimates Decline Curve Analysis

Material balance calculations

Reservoir Simulation



THE EDUCATED GUESS and/orCOMPARISON OF NEARBY PRODUCTION

•Consider a region where production is from ahighly fractured tight formation or whereporoperm heterogeneity is unpredictable.

• Volumetric calculations are largelymeaningless.

• A way to estimate potential production from

a well is to consider those nearby.• Generally, such a wildcat well will not

perform better than the nearest wells: best to

ti t ti l



estimate cautiously

VOLUMETRICS

• Most accurate and widely used methods of reservesestimation.

• Carried out by geologists as they are based ongeological structure and isopach maps.

• Rock volumes are established that are assumed to

contain hydrocarbons (e.g. seismic bright spot).• Can be a simple volume calculation or a complex net

gas or net oil isopach approach, determined by

structure contours modified by fluid contacts and netisopachs (net reservoir thickness map).

• Accuracy of volumetrics depends on data for porosity,saturation, net thickness, areal extent, formation

l f t i t g it f th d t ithi i



volume factor, integrity of those data within a reservoir.

Volumetric Method• RR = 7758 x A.t x φ(1 – Sw) x FVF x RF

• Amount of oil in reservoir • Amount of recoverable oil

RR = Recoverable Reserves 7758 = conversion from acreft to barrels (if vol. in

m3. this conversion number is eliminated)

A = area of porous rock, acre

t = thickness in feet

φ = porosity,%

(1-Sw) = water saturation of reservoir

FVF Formation Volume Factor (1/Bo & 1/Bg)



FVF = Formation Volume Factor (1/Bo & 1/Bg) Bo/Bg reservoir volume / surface volume (vr / vs )

RF = Recovery Factor



HORIZON MAP(Superimposed Structure and Net Isopach Maps)

0 m

5 m

1 0 m

1 5 m

1 0 m

5 m



5 m

0 m

NET PAY MAP



Rock Volume Calculations2 methods :

1. PYRAMID

2. TRAPEZOIDS

A : area, m2 or acre

h : isopach/contour interval, m or ft



h : isopach/contour interval, m or ftn : contour number (0 n)t : avg. thickness above the top of max. thickness

FVF

ormation Volume Factor



RFRecovery Factor

• Usually RF determination is carried out by

Reservoir Engineer.

• Mainly based on the reservoir drive, rock

properties and fluid properties.

• For oil with effective water drive the

primary recoveries are in 25 – 40 % range(max. 75%).

• For gas with gravity drainage water drived d l i d i id RF 80%



• For gas with gravity drainage, water driveand depletion drive can provide RF > 80%.

Average Oil RecoveryFactors,% of OOIP

Drive Mechanism

Range AverageSolution-gas drive 5 - 30 15Gas-cap drive 15 - 50 30Water drive 30 - 60 40

Gravity-drainagedrive

16 - 85 50

Average Gas RecoveryFactors,

% of OGIPDrive Mechanism

Range Average

Volumetric reservoir(G i d i )

70 - 90 80

Average Recovery Factors



Volumetric reservoir(Gas expansion drive)

70 90 80

Water drive 35 - 65 50

SOURCESOF ATA





Decline Curve Analysis

(Reservoir Engineer’s jobs)

• After wells have been producing for a while:

– The rate of production is graphed

– Generally 6 months – 1 year after start of

production• Good reserves estimates can be derived.

Often compared with volumetric techniqueresults.

• Can be done by well, by a group of well, by

block, by reservoir, by field



block, by reservoir, by field

Decline Analysis Results• Determine remaining recoverable reserves

under natural depletion rate.

• To forecast production under existingconditions

• Limitation: – The degree of the accuracy is depend on the

reliability of the production data.



reliability of the production data.

DECLINECURVE

EQUATIONS



Production Plots

1. A plot of log(q) vs t is

Linear if decline is exponential Concave upward if decline is hyperbolic (n>0) or harmonic

2. A plot of q vs Np is Linear if decline is exponential

Concave upward if decline is hyperbolic(n>0) or harmonic

3. A plot of log(q) vs Np is Linear if decline is harmonic

Concave downward if decline is hyperbolic (n<1) or exponential Concave upward if decline is hyperbolic with n>1.

4. A plot of 1/q vs t is Linear if decline is harmonic

Concave downward if decline is hyperbolic (n<1) or exponential Concave upward if decline is hyperbolic with n>1.



Concave upward if decline is hyperbolic with n>1.

Example. Exponential declinexample. Exponential decline

Example. Exponential decline

q = 6049.1e-0.0524 t

100

1000

10000

0 10 20 30 40 50 60time (quarter year)

R a t e , s t b / d

.

Slope=-D 1/quarter year



time (quarter year)

Example. Exponential declinexample. Exponential decline

Example. Rate decline with production

q = -0.4301Np + 5768.7

0

1000

2000

3000

4000

5000

6000

7000

0 2000 4000 6000 8000 10000 12000 14000

Cum prod MSTB

q s t b / d

q abondonment

Reserves



Cum. prod, MSTB

Example. Harmonic declinexample. Harmonic decline

0

2000

4000

6000

8000

10000

12000

0 2 4 6 8 10 12 14 16

Time (years)

R a t e ( s t b / d )

0

5

10

15

20

25

30

35

40

C u m .

P r o d u c t i o n ( M M s t b )



Example. Hyperbolic declinexample. Hyperbolic decline

Hyperbolic Decline curve

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 50 100 150 200 250 300 350

q S T B /



days

General Concept of Material Balance.

From: Petroleum Reservoir Engineering

— Amyx, Bass, and Whiting (1960).

a. Initial reservoir conditions. b. Conditions after producing N p

STB of oil,and G p SCF of gas, and W p STB of water.

Material Balance: Key Issues

Must have accurate production measurements (oil, water, gas). Estimates of average reservoir pressure (from pressure tests). Suites of PVT data (oil gas water)

MATERIAL BALANCEMATERIAL BALANCE

of a Petroleum Reservoir(Mostly carried out by Reservoir Engineer)



Suites of PVT data (oil, gas, water).

Reservoir properties: saturations, formation compressibility, etc.

RESERVOIR SIMULATION (RS)RESERVOIR SIMULATION (RS)

• Reservoir Modelling: primarily the reservoirengineer’s job.

• RS applies the concepts and techniques of math-ematical modeling to the analysis of the behavior ofpetroleum reservoir systems.

• In a narrower sense refers only to the hydro-

dinamics of flow within reservoir.• In a larger sense refer to the total petroleum

system which includes the reservoir, the surface

facilities, and any interrelated significant activity, andeconomic

• The basic flow model the partial differentialequations using finite difference methods whichgovern the unsteady state flow of all fluid phases inh i di



the reservoir medium.

RESERVOIRRESERVOIR

SIMULATORSIMULATOR

Rock data

Fluid data

Production data

Pressure data

Flow rate data

Mechanical &operational data

Miscellaneousdata

INPUTINPUT PROCESSEDPROCESSED

in the BLACK BOXin the BLACK BOXOUTPUTOUTPUT

Reserves

Reservoir modelPlan of reservoirdepletion

Productionforecast

Optimumproduction

RESERVOIR SIMULATIONESERVOIR SIMULATION







Reservoir link with surface facility



• Prepare the array input data (maps) of individual flow

unit : structure (top & bottom), isopach (net & gross),porosity, permeability, rock compressibility etc.

• Advising to simulation engineer in the designing of

the grid model and layer divisions.• Trace and established in the model grid the

existence of faults, horizontal and vertical barriers

permeability.• During the history matching of production, pressure

etc., DG advises to simulation engineer in allowable

geological modification such as thickness, structure,rock properties and volumetric reserves.

The Role of DGThe Role of DG

in Reservoir Simulationin Reservoir Simulation



rock properties and volumetric reserves.

RESERVES CLASIFICATIONS

• PROVED : – Estimated to reasonable certainty. Often based on

well logs but normally requires actual production or

formation tests. – Proved developed reserves – Reserves that are expected to be recovered from existing wells

– Proved undeveloped reserves

– To be recovered by new drilling, deepening wells to a newreservoir or where additional finance is required to produce

• PROBABLE RESERVES – Less certain than proved but can be assessed to

some degree of certainty. May include loggingestimates, improved recovery technique estimates

• POSSIBLE RESERVES

– Not as certain as probable reserves and can only beestimated to a low degree of confidence.



• UNPROVED RESERVES Resources

RESERVES CLASSIFICATIONS



Decision Making: protocol• Despite these defined terms, there is still some latitude in their

application. In general, we use this:

• Proved Reserves = minimum case economics. Financialinvestment is based on proved reserves.

• Proved + Probable Reserves = most likely caseeconomics. Internal company decisions usually based on this.

• Proved +Probable + Possible Reserves = maximum

case economics. This is the best that could reasonably happenfor a venture. Companies try to sell ventures based on this.



MM DARISSALAM, YOGYAKARTA JUN. ‘08



Documents

[p.T] Petroleum Development Geology