PETROLEUM PRODUCTION METHODS
SUBSURFACE PRODUCTION ENGINEERINGCourse Instructor: Muhammad
AliEmail: [email protected]
LECTURE - 01
1
The aim of this course is to provide familiarization of the
principles and applications of various theories and techniques
necessary to design, estimate and maximize production performance
in a cost effective manner within various constraints from the oil
and gas well systems. . Course content2
1. Introduction to Subsurface Production Engineering2. Reservoir
inflow performance3. Artificial lifting methods and Design4.
Formation Damage5. Matrix Acidizing6. Hydraulic Fracturing7. Sand
Control8. Separators9. Flow Assurance10. Field Development Concepts
& Fluid Processing onshore and offshoreRole of a production
engineer3
The role of the Production Technologist is extremely broad.
Currently within theoperating companies in the petroleum industry,
the role and responsibility can be broadly said to be responsible
for the production system.What You'll Do
production engineer responsibilities include:
Production monitoring and evaluationAsset management
planningWorkover design and executionProduction equipment
designCost estimating and budgetingInterfacing with working
interest partners, service companies and regulatory agencies
Production System4
Petroleum production involves two distinct but intimately
connected general systems:
the reservoir, which is a porous medium with unique storage and
flow characteristics;
and the artificial structures, which include the well,
bottomhole, and wellhead assemblies, as well as the surface
gathering, separation, and storage facilities.
Production system5
The production system is a composite term describing the entire
production processand includes the following principal
components:-
(1) The reservoir - it productive capacity and dynamic
production characteristicsover the envisaged life of the
development.
(2) The wellbore - the production interval, the sump and the
fluids in the wellbore
(3) Production Conduit - comprising the tubing and the tubing
components
(4) Wellhead, Xmas Tree and Flow Lines
(5) Treatment FacilitiesProduction system6
From the above definition it can be seen that the
responsibilities of ProductionTechnology cover primarily subsurface
aspects of the system but they can also extendto some of the
surface facilities and treatment capabilities, depending on the
operatingcompany.The role of the Production Technologist is one of
achieving optimum performancefrom the production system and to
achieve this the technologist must understand fullythe chemical and
physical characteristics of the fluids which are to be produced
andalso the engineering systems which will be utilised to control
the efficient and safeproduction/injection of fluids. 6Role of
production engineer7
(1) Production Engineering:Fluid flowReservoir dynamicsEquipment
design, installation, operation and fault diagnosis
(2) Production Chemistry:The Fluids - produced, injected and
treatment fluidsThe Rock - mineralogy, physical/chemical properties
and rock strength andresponse to fluid flow. What oil company
expects Production technology contributes substantially as one of
the major technical functions within an operating company and in
particular, to its economic performance and cashflow.
CashflowThe overall objectives would ideally be to maximise both
cashflow and recoverable reserves. This would normally require
maintaining the well in an operational state to achieve(a) maximum
production rates(b) maximum economic longevity(c) minimum down
time8
What oil company expects 9
What oil company expects
10
Economic phases of field development and input from production
technology What oil company expects 11
(2) CostsIn this category there would be both fixed and direct
costs, the fixed costs being thoseassociated by conducting the
operation and the direct or variable costs beingassociated with the
level of production and the nature of the operating problems.
Thelatter costs are therefore defined in terms of cost per barrel
of oil produced. On thisbasis the production technologist would
seek to:
(i) Minimise capital costs(ii) Minimise production costs(iii)
Minimise treatment costs(iv) Minimise workover costsTIME SCALE OF
INVOLVEMENT12
The production technologist is involved in the initial well
design and will have interests in the drilling operation from the
time that the reservoir is penetrated. In addition his inputs will
last throughout the production life of the well, to its ultimate
abandonment. Thus the production technologist will contribute to
company operations on a well from initial planning to
abandonment.
PHASE NATURE OF INPUT/ACTIVITY
Drilling Casing string designDrilling fluid SelectionCompletion
Design/installation of completion stringProduction Monitoring well
and completion performanceWorkover/Recompletion
Diagnosis/recommendation/ installation ofnew or improved production
systemsAbandonment Identify candidates and proceduresKEY SUBJECT
AREAS IN PRODUCTION TECHNOLOGYProduction technology is both a
diverse and complex area. With the on-going development of the
Petroleum Industry the scope of the technological activities
continues to expand and as always increases in depth and
complexity. It is however, possible to identify several key subject
areas within Production Technology namely:-
1) Well Productivity2) Well Completion3) Well Stimulation4)
Associated Production Problems5) Remedial and Workover Techniques6)
Artificial Lift / Productivity Enhancement7) Surface Processing
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Well productivity14
Well productivity15
An oil or gas reservoir contains highly compressible hydrocarbon
fluids at an elevated pressure and temperature and as such, the
fluid stores up within itself considerable energy of
compression.
The efficient production of fluids from a reservoir requires the
effective dissipation of this energy through the production
system.
Optimum utilisation of this energy is an essential part of a
successful completion design and ultimately of field development
economics. Well productivity16
The productivity of the system is dependent on the pressure loss
which occurs inseveral areas of the flow system namely:-
The reservoir The wellbore The tubing string The choke The flow
line The separatorWell productivity17
Well productivity18
. Under natural flowing conditions the reservoir pressure must
provide all the energy to operate the system i.e. all the pressure
drop in the system.
PR = DPSYSTEM + PSEP
where;PR = reservoir pressureDPSYSTEM = total system pressure
dropPSEP = separator pressure
The optimum distribution of energy between these various areas
has a major bearing on the cost effectiveness of a well design and
hence production costs.Well productivityThe pressure drop which
occurs across the reservoir, DPRES and is defined as the inflow
performance relationship or IPR. The pressure drop and causes floe
is in the tubing and wellbore DPTBG is that which occurs in lifting
the fluids from the reservoir to the surface and it is known as the
vertical lift performance or VLP, or the tubing performance
relationship or TPR,
i.e. for natural flow R = DPRES + DPTBG + PTHWhere;PTH = Tubing
head pressure
The pressure drop across the reservoir, the tubing and choke are
rate dependant andthese relationships therefore define the means by
which we can optimise the productionof the fluid from the
reservoir.
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Well productivity20
limitations on the extent to which we can optimise the
dissipation of this energy. These are the following:-
Limited Reservoir Pressure
Minimum Surface PressureWELL COMPLETION21
the major proportion of production technology activities have
been concerned with the engineering and installation of the down
hole completion equipment.
The completion string is a critical component of the production
system and to be effective it must be efficiently designed,
installed and maintained.Well completion22
Increasingly, with moves to higher reservoir pressures and more
hostile development areas, the actual capital costs of the
completion string has become a significant proportion of the
totalwell cost and thus worthy of greater technical consideration
and optimisation.
(1) The fluids which will be used to fill the wellbore during
the completion process
.(2) The completion must consider and specify how the fluids
will enter thewellbore from the formation i.e
(3) The design of the completion string itself must provide the
required containmentcapability to allow fluids to flow safely to
the surface with minimal loss inpressure. Well completion23
Well stimulation24
WHY STIMULATION IS NEEDED?
The productivity of a well naturally arises from the compressed
state of the fluids, theirmobility and the flow properties of the
rock, primarily in terms of permeability.
In some cases reservoirs may contain substantial reserves of
hydrocarbons but thedegree of inter-connection of the pore space
and the ease with which the fluids canflow through the rock, may be
very poor.
In such situations it may be beneficial to stimulate the
production capacity of the well.WELL STIMULATIONStimulation
techniques are intended to:-
(1) Improve the degree of inter-connection between the pore
space, particularly forlow permeability or vugular rocks
(2) Remove or bypass impediments to flow, e.g.. damage.
(3) Provide a large conductive hydraulic channel which will
allow the wellbore tocommunicate with a larger area of the
reservoir.25
WELL STIMULATION26
In general, there are four principal techniques applied,
namely:-
Propped Hydraulic Fracturing
Acid FracturingAssociated Production Problems27
The on going process of producing hydrocarbons from a well is a
dynamic process andthis is often evidenced in terms of changes in
the rock or fluid production characteristics.
Physico-chemical changes
Associated Production Problems28
The on going process of producing hydrocarbons from a well is a
dynamic process andthis is often evidenced in terms of changes in
the rock or fluid production characteristics.
Physico-chemical changes
Incompatibility between reservoir fluids and those introduced
into the wellbore which may result in formation damage, e. g.,
scale deposits or emulsions.
Associated Production Problems29
The mechanical collapse or breakdown of the formation may give
rise to the production of individual grains or "clumps" of
formation sand with the produced fluids..
Associated Production Problems30
In formations containing siliceous or clay fines, these may be
produced with thehydrocarbons creating plugging in the reservoir
and wellbore.
Associated Production Problems31
Corrosion due to the inherent corrosive nature of some of the
components
Processing problems can be encountered such as radioactive
scales, foams,heavy metals deposits, etc.
Workover TechniquesIdentification of problems and their
source32
The production technologist is responsible for monitoring and
ensuring the ongoingsafe operation of the well. As such the
responsibilities include:-WORKOVER TECHNIQUES33
Plan the required corrective action - this requires considerable
attention todetail and will necessitate:-
(a) Identifying the equipment, manpower and other capabilities
required.(b) Identification and assessment of the
unknowns/uncertainties.(c) Identification and evaluation of the key
safety points and mile stones.(3) The assessment of the probability
of technical and economic success.(4) To identify the required
resources, skills and their supervision.(5) The workover phase is
the most dangerous in terms of well control and thepotential for
damage on existing production wells. Attention to detail andcareful
planning is essential.Artificial Lift34
wells will produce under natural flow conditions when reservoir
pressure will support sustainable flow by meeting the entire
pressure loss requirements between the reservoir and separator. In
cases where reservoir pressure is insufficient to lift fluid to
surface or at an economic rate, it may be necessary to assist in
the lift process by either:-
Reducing flowing pressure gradients in the tubing e.g. reducing
the hydrostatichead by injecting gas into the stream of produced
fluids. This process is known asgaslift.
Providing additional power using a pump, to provide the energy
to provide part orall of the pressure loss which will occur in the
tubing.ARTIFICIAL LIFT35
In the case of gas lift, the pressure gradients will be reduced
because of the change influid composition in the tubing above the
point of injection.
When pumps are used, apart from fluid recompression and the
associated fluidproperties, there is no change in fluid
composition. There are many specificmechanisms for providing pump
power and the lift mechanism. e.g.
Electrical powered centrifugal pumps Hydraulic powered
centrifugal/turbine, jet and reciprocating pumps Sucker rod and
screw pumps
Each artificial lift system has a preferred operating and
economic envelope influencedby factors such as fluid gravity,
G.O.R., production rate as well as development factorssuch as well
type, location and availability of power.THANK YOU36
