Gas Hydrate Research Review

ByShirish Patil

Associate ProfessorPetroleum Development Laboratory

University of Alaska Fairbanks

Alaska Gas Hydrate Planning WorkshopAnchorage, AK

August 17-18, 2005

Energy Technology DivisionArgonne National Laboratory

PDL-UAF 1987

Gas Hydrate Research at UAF(1983-2005)

Gas Hydrate Phase Behavior

S. PatilV.Kamath

A.DandekarS. Paranjape

W. ChenJ. Westervelt

Gas Hydrate Relative Permeability

S. PatilA. DandekarN. Jaiswal

Gas Hydrate Production Modeling

S. PatilN. Nanchary

D. OgbeA. Dandekar

C. BaenaR. Roadifer

V. SrivastavaD. ScottS. Howe

V. Gandibhan

Gas Hydrate Production TechniquesS. Patil

A.DandekarV. KamathM. NademP. Mutalik

J. Sira

Gas Hydrate Formation Damage

S. PatilA. Dandekar

P. Kerkar

Gas Hydrate Production Economics

S. PatilA. DandekarD. Reynolds

S. HoweS. Omenihu

18 M.S. ThesisOver 70 Papers and Reports

Government-Academia-Industry PartnershipLeading to Technology Transfer and Resource Development

PNNL, LBNLANL

UAF

BPXA

CPAlaska

NETL

Experimental &

Modeling Tasks

FieldApplications

TechnologyTransfer

Applications to ANS ShallowResource Development-

State of AlaskaTrained UAF Graduates

(Industry)

(University+Government)

Resource Development

USGS DGGS

UAF Facilities- Petroleum Dev. Lab.

Composite of A-F Hydrates

Milne Pt 3D Survey

Collett et al 1-2004

Milne Point Gas Hydrate Accumulation

Resource Characterization and Quantification of Natural Gas-Hydrate and Associated Free-Gas

Accumulations Prudhoe Bay – Kuparuk River Area, North Slope of Alaska

BP Exploration (Alaska), Inc.Principal Investigator: Robert Hunter

University of Alaska FairbanksPrincipal Investigator : Shirish PatilUnited States Geological Survey

Principal Investigator : Timothy CollettUniversity of Arizona-Tucson

Principal Investigator : Mary PoultonU.S. Department of Energy

Project Manager: Ray Boswell

Gas Hydrate Research Projects at UAF

Alaska Methane HydrateProject

BPXA, UAF, UAz, USGSFunded By

NETL, USDOEHunter, Patil, Casavant, Collett

Poulton &Dandekar(2002)Injection of CO2 for Recovery of

Methane From Gas Hydrate Reservoirs

UAF-PNNL-BPMcGrail, Zhu, Patil, Hunter, Bush

Funded By AETDL (2002)

Novel Chemically Bonded Phosphate Ceramic Borehole Sealants

for Arctic EnvironmentUAF-ANL-BJ ServicesPatil, Wagh, Dawson

Funded by AETDL(2004)

Compliments Recovery/Sequestration

Compliments Completions/Cementing/Infrastructure

Resource Characterization/ Reservoir Engineering/Drilling & Production research potentially leading to successful Pilot Project

Engineering research laboratories

Unique location

Over 20 years of proven research capabilities

Strong industry/Government partnerships

Gas Hydrate Research Focus Groups

Phase Behavior Studies- Jason WesterveltShirish Patil, Abhijit Dandekar

Relative Permeability Studies-Namit Jaiswal

Shirish Patil,Abhijit Dandekar

Reservoir Modeling and Economics- Stephen HoweShirish Patil, David Ogbe, Abhijit Dandekar

Drilling Fluids & Formation Damage- Prasad KerkarShirish Patil, Abhijit Dandekar

BPXA

USGSPHASE 2

PHASE 1

Examples of Hydrate Stability CurvesDepth of Hydrate Stability

Zone for the NW Eileen State 2 Well

0

200

400

600

800

1000

1200260 270 280 290

Temperature (K)

Dep

th (m

)

Geothermal Gradient

Run 1

Run 2

Top of HSZ - 175 m

Base of Permafrost

Base of HSZ - 710 m

Depth of Hydrate Stability Zone for the NW Eileen State 2

Well0

200

400

600

800

1000

1200260 270 280 290

Temperature (K)

Dep

th (m

)

Geothermal GradientRun 1Run 2Run 3

Top of HSZ - 180 m

Base of Permafrost

Base of HSZ - 705 m

Depth of Hydrate Stability Zone for the NW Eileen State 2

Well0

200

400

600

800

1000

1200260 270 280 290

Temperature (K)

Dep

th (m

)

Geothermal GradientRun 1Run 2Run 3

Top of HSZ - 195 m

Base of Permafrost

Base of HSZ - 715 m

Without Porous Media (h=535) Synthetic Porous Media (h=525) Field Sample (h= 520)

Phase Behavior Studies

Hydrates Without Porous MediaHSZ for the Dissociation of Bulk Hydrates

0

200

400

600

800

1000

WK-11 WK-14 WK-17 NW Eileen NHST

Dep

th (m

)

2% Brine 4% Brine

(Hydrates in Presence of Anadarko Hot Ice #1 Core Sample)

HSZ for the Dissociation of Anadarko Sample

0

200

400

600

800

1000

WK-11 WK-14 WK-17 NW Eileen NHST

Dep

th (m

)

2% Brine 4% Brine

• Arco and Exxon Core (1972)– Depth 577 to 776 m

(Red)

• Log Data (Collett 1993)– Depth 575 to 675 m

(Blue)

• This study – Depth 190 to 740 m

(Green)

Depth of Hydrate Stabiltiy Zone for the NW Eileen State

2 Well0

200

400

600

800

1000

1200260 270 280 290

Temperature (K)D

epth

(m)

Geothermal GradientRun 1Run 2Run 3

Top of HSZ - 190 m

Base of HSZ - 740 m

Base of Permafrost

Objectives of Study

Formation Damage Assessment through Drilling Fluids Dynamic Filtration for the Production of

Gas Hydrates on the North Slope of Alaska

• Evaluate Drilling Fluid to assess Formation Damage• Permeability impairment data for near well bore formation

to predict production data, recovery factor and economics• Filtrate loss amount to formation for various mud

composition to simulate on whole length of well

Conceptual Design: Dynamic Filtration

Gap

vn

rr

vn

DD

vn

OHOHw .2

)12(8.0

)(2

)12(8.0).12(8.0 +=

−

+=

−

+=γ

Overburden fluid

Coolant in

Coolant Out

Filtrate Core sample

Drilling Mud StorageDiaphragm Pump

Air

Floating Piston Accumulator

Refrigerated Circulator G-L Separator 1

G-L Separator 2

SR4J-580

N2

SR4J-580

N2

SR4J-350

CH4

BP50 BP50

GMFM1 GMFM2

A

Drilling Fluid Recirculation System

Drain Mud Face

Mud Vent Valve

Vent Mud Face

Bypass

B

Mud Fill Valve

Bypass

DFCH

N2

SR4J-580

Vacuum

Drilling Fluid Drain

Air

P1

P4

P2

P5

P6

P3

Drain

Exhaust

Q

Refill Valve

ISCO 500DX PUMP

Q

System Design and Development

Procedure• Core sample preparation & porosity

measurement • Preparation of recirculation system • Measurement of initial absolute permeability• Dynamic filtration at Overbalance

Pressure• Measurement of damaged permeability in

wellbore to reservoir direction • Measurement of return permeability in

reservoir to wellbore direction

Drilling Fluids RheologyBM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

Composition n klbf.secn/100 ft2

PVcp

Shear Ratesec-1

Flow Rategpm

Linear Velocity

ft/min30 0.3503 10.9

40 0.4671 14.3

80 0.9342 28.8

30 0.3087 9.5

40 0.4116 12.7

80 0.8231 25.4

30 0.3626 11.2

40 0.4835 14.9

80 0.9671 29.8

30 0.3626 11.2

40 0.4835 14.9

80 0.9671 29.8

BM + 50 gm + 50 gm Q-Broxin

0.7365 0.03037 2

BM + 50 gm + 15 gm Dextrid

0.7365 0.04555 3

BM + 50 gm KCl

0.5142 0.1417 1.5

BM 0.6777 0.03653 1.5

Effect of Shear Rate and Overbalance on Base Mud

Damage

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

0.0

0.2

0.4

0.6

0.8

1.0

30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi

k/ko

(ko-

initi

al p

erm

eabi

lity)

Damaged Return

Effect of Shear Rate and Overbalance on Flocculated Mud Damage

0.0

0.2

0.4

0.6

0.8

1.0

30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi

k/ko

(ko-

initi

al p

erm

eabi

lity)

Damaged Return

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite+ 0.5 gm KOH + 3 gm Quickgel

Effect of Shear Rate and Overbalance on Mackenzie Mud Damage

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

Effect of Filtration Control Agent

0.0

0.2

0.4

0.6

0.8

1.0

30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi

k/ko

(ko-

initi

al p

erm

eabi

lity)

Damaged Return

Effect of Shear Rate and Overbalance on Dispersed Mud Damage

0.0

0.2

0.4

0.6

0.8

1.0

30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi

k/ko

(ko-

initi

al p

erm

eabi

lity)

Damaged Return

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

Static and Dynamic Filtration (40 sec-1) of Mackenzie Mud

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60

Cumulative time, min

Cum

ulat

ive

Volu

me,

ml

Static Filtration Dynamic Filtration

Static and Dynamic Filtration (80 sec-1) of Dispersed Mud

050

100150

200250

300350

400

0 10 20 30 40 50 60

Cumulative time, min

Cum

ulat

ive

Vol

ume,

ml

Static Filtration Dynamic Filtration

BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel

Conclusions• Annular fluid velocity or shear rate has pronounced effect on

dynamic fluid loss; however, the addition of filtration control agent gives reverse trend.

• Greater overbalance pressure causes more fluid leak-off and more damage. Damage at 200 psi overbalance was severe.

• Permeability impairment is strongly dependent on the state of dispersion of mud. The defloculated mud with lignosulfatecauses more damage by invading deeper with samllerparticles. The floculated mud gives poor quality filter cake, with more filtrate loss into the formation. The drilling fluid formulation giving a low permeability, high strength external mud cake would be ideal to minimize formation damage.

• Presence of filtration control agent (Dextrid) reduces the spurt loss and subsequent filtration rates significantly. The return permeability is found to be 94% after mud circulation at 80 sec-1 shear rate.

Schematic of laboratory set-up for formation of hydrates and relative permeability measurements

BR: Back pressure regulator G.F.M: Gas flow meterP.G: Propylene glycol C: Piston cylinderM. Cyl.: Measuring vessel P: Differential pressure transducer

Relative Permeability Studies

Measured water and gas relative permeability data for different hydrate saturations in Oklahoma 100 mesh sand

sample and Hot-Ice Samples

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.2 0.4 0.6 0.8 1.0

Gas saturation, fraction

k rw

, fra

ctio

n

5%10%17%23%29%36%

0

0.01

0.02

0.03

0.04

0.05

0.06

0.0 0.2 0.4 0.6 0.8 1.0

Gas saturation, fraction

k rg,

frac

tion

5%10%17%23%29%36%

0.0

0.2

0.4

0.6

0.8

1.0

0 0.2 0.4 0.6 0.8 1

Gas saturation, fraction

k rw

, fra

ctio

n

7%2131

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.0 0.2 0.4 0.6 0.8 1.0

Gas saturation, fraction

k rg,

frac

tion

7%21%31%

Water and Gas relative permeability as a function of hydrate saturation for different iso-gas saturation values for Oklahoma 100 mesh sand and Hot-

Ice Samples

0.01

0.1

1

0 5 10 15 20 25 30 35 40

Hydrate saturation, %

krw

, fra

ctio

n

Sg=20%Sg=40%Sg=60%

0.0001

0.001

0.01

0.1

0 10 20 30 40

Hydrate saturation, %

k rg,

frac

tion

Sg=20%

Sg=40%

Sg=60%

0.001

0.01

0.1

1

0 10 20 30

Hydrate saturation, %

k rw

, fra

ctio

n

Sg=20%Sg=40%Sg=60%

0.0001

0.001

0.01

0.1

0 10 20 30

Hydrate saturation, %

k rg,

frac

tion

Sg=20%Sg=40%Sg=60%

Relative Permeability- Conclusions• Thus from the results in this study it is confirmed that the type of hydrate

growth not only depends on a number of sediment parameters, including grain size, porosity, structure, but also on parameters such as non-uniform dissociation, fluid parameters such as viscosity and the method of forming hydrates.

• Relative permeability inferred from unsteady state core floods conducted in this study is a lumped parameter which not only includes hydrate saturation but also the effects of dissociation instabilities caused by fluid flow, fines migration due to gas production and local compaction in porous media at low temperature.

• The relative permeability curves generated in the laboratory for sand samples and Anadarko field samples, to a great extent describe the field behavior of two phase flow in the presence of hydrates and would help in effective reservoir modeling for gas production from hydrate formations.

Initialization of Simulation

Reservoir Characterization

Porosity 36%

Permeability 300mD

Hydrate Saturation 0.7

Gas Saturation (hydrate zone) 0.1

Gas Saturation (gas zone) 0.8

Water Saturation 0.2

Max. Well Flow Rate 25 mmscfd

¾ of block hydrate, ¼ free gas

Scenario ran for 15 years

Production Modeling & Economic Evaluation of a Potential Gas Hydrate Pilot Production

Program on the North Slope of Alaska

Gas Production• The production remains on

plateau at a rate of 50 mmscfd for over three years. The main contributor during the plateau is likely to be the free gas and when this is depleted the rate quickly diminishes

• After the rate fall, the decline is steadier, as the dissociation of the hydrate supports production.

• Total Cumulative Production = 161.5 bcf

Daily Gas Production Rate

0

10

20

30

40

50

60

0 2000 4000 6000

time (days)

mm

scfd

Movement of Dissociation Front

At start of Simulation

After 6 months of production from the free gas zone, first signs of dissociation are seen

3 years: dissociation at margins has moved over 1 mile up dip

Cross Section of Reservoir at 6 years shows complete dissociation 400 meters up dip of the well and partial dissociation up to 1 mile distant8 Years

13 years: partial dissociation throughout most of reservoir

15 years: signs of dissociation in all areas of reservoir

Reservoir Cooling

Start of Simulation, temperatures equal geothermal gradient

After 1 year of production, the free gas zone has cooled slightly due to gas expansion. The area of hydrate beginning dissociation has also cooled

3 years: The area of dissociation has cooled to near freezing10 years and low temperature zone expands

At end of simulation (15 years), majority of hydrate zone is near freezing. The section near the well, which by this time is free of hydrate increases in temperature as heat flows from surrounding rocks

Economic Evaluation - SensitivityTornado Diagram +/- 10% Variation

-12.4

-25.1

3.7

3.7

4.2

22.3

32.7

6.3

6.3

5.8

-30 -20 -10 0 10 20 30 40

Gas Price

AK Gas Line

Capex

Lifting Costs

Royalty

NPV ($mm)

Conclusions• While recognizing this study had limitations, this was best

way forward at that time. This research has been refined to a great deal at present.

• The volumes of gas produced in base case scenario are sufficient to produce a ROR on investment cost of the project, though this is very dependent on gas price and transportation tariff. A reduced permeability results in an economic loss, though it can be overcome by expanding the project to reduce the burden of pipeline capital costs.

• Area of concern is the lowering of reservoir temperature, leading to freezing of water and plugging the formation and preventing efficient depressurization.

• Substantial depletion of a reservoir using depressurization alone would be a lengthy process and as such, methods to increase the rate of dissociation should be investigated for effectiveness and economic impact.

Partnership for Economic Development

Alaska

Impact to UA, UAF, StateUA Strategic PlanGoal 3: Research Excellence Goal 5: Responsiveness to State NeedsConduct research that solves problems of importance to the state, the nation, the north, and the world.Meet the educational, cultural, and economic needs of the diverse peoples of Alaska.Increase opportunities for undergraduate and graduate student participation in research.Capture Alaska-specific opportunities for the State and the University.Establish strong research relationships with the private sector and government agencies that address issues of importance to Alaska.Communicate the value of University research in terms of the University’s educational quality and Alaska’s economy

Trained UA/UAF GraduatesNew reserves to declining productionEconomic Development

UAF Petroleum Engineering Hydrate Research Group Student Success at National Competitions

Phillip Tsunemori (B.S.)1st Place 2004 SPE WRM

Namit Jaiswal (M.S.)-3rd Place 2004 SPE WRM

Sudiptya Banerjee (M.S.)-1st Place 2005 AADE, and3rd Place 2005 SPE WRM

Prasad Kerkar(M.S.)- 3rd Place

2005 AADE

UAF- In Communication With All Hydrate Resource Development Projects

India

Japan

Gulf of Mexico

Alaska Canada

Acknowledgement

• Robert Hunter and Scott Digert, BPXA• Brad Tomer and Ray Boswell, NETL, US DOE• Tim Collett, USGS• Brent Sheets and Jim Hemsath, AEO, US DOE• Scott Wilson, Ryder-Scott

Thank you.