Q. - Harold Vance Department of Petroleum Engineering - Texas

Slide — 1/32T.A. Blasingame Performance-Based Reservoir Characterization — State-of-the-Technology

SPE DISTINGUISHED LECTURER SERIESis funded principally

through a grant of the

SPE FOUNDATIONThe Society gratefully acknowledges

those companies that support the programby allowing their professionals

to participate as Lecturers.

And special thanks to The American Institute of Mining, Metallurgical,and Petroleum Engineers (AIME) for their contribution to the program.

Society of Petroleum EngineersDistinguished Lecturer 2005-06 Lecture Season



Performance-Based ReservoirCharacterization – State-of-the-Technology

Thomas A. Blasingame, Texas A&M U.Department of Petroleum Engineering

Texas A&M UniversityCollege Station, TX 77843-3116

+1.979.845.2292 — [email protected] materials located at:

link → http://www.pe.tamu.edu/blasingame/data/folder → z_SPE_DL


Prelude: Performance-Based Reservoir Characterization

Q. What is "Performance-Based Reservoir Characterization?"A. In the context of this lecture, "Performance-Based Reservoir Charac-

terization" is the diagnosis, analysis, and interpretation of production data taken from an individual well — and the integration of the results of this analysis with other forms of data (e.g., petrophysical data, re-sults of well test analysis, geological data, etc.).

(0.5 min)


Guidelines: Performance-Based Reservoir CharacterizationsREVIEW production data for consistency (allocations, accuracy, etc.).REVIEW well history, particularly recompletions/stimulations.GATHER/CORRELATE petrophysical data (core, logs, etc.).PERFORM simplified analysis of production data (Arps, EUR, etc.).

REVIEW measured rate/pressures (quality check).PERFORM model-based analysis of production (and well test) data.

INTEGRATE results at different scales (without reservoir simulation).

Prelude: Guidelines for Production Analysis (4 min)


Primer: Reservoir Engineering

Q. What do I need to know for reservoir engineering ... ?A. All you need is ... Darcy's law and material balance.

Darcy's Law:

Oil Material Balance Eq.: (p>pb)

poio

ti N

BB

Ncpp 1−=

⎥⎦⎤

⎢⎣⎡

∂∂

−=rpr

Bkhqμ2.141

1)(

Oil Diffusivity Eq.: (p>pb)

Oil Pseudosteady-State Flow Eq.: (p>pb)

owA

oowf qs

r

ACekh

Bpp 2

14ln 21 141.2

⎥⎥

⎦

⎤

⎢⎢

⎣

⎡+

⎥⎥⎦

⎤

⎢⎢⎣

⎡+=

γμ

tp

kc

rp

rr

p t∂∂

=∂∂

+∂

∂ φμ0002637.0

112

2

(0.5 min)


Orientation: Production Analysis (PA) Data

Q. What is Production Analysis (PA)?A. Combined analysis of rate and flowing bottomhole pressure data.

(0.5 min)


Orientation: PA Data Analysis Example (Gas)

Q. Does material balance time function correctly? (use an example)A. Typical low productivity gas well example (mid-Continent US).

(1 min)


History: Production Analysis (PA)

Q. History of Production Analysis (PA)?A. Various "historical" stages — see below:

PA up to 1970? (estimate reserves, maximum rate, and future rates)PA 1970-1990? (estimate reservoir properties — simple models [pwf=con])PA 1990-2000? (estimate reservoir properties — general q and pwf profiles)PA 2000-? (interactive diagnosis, analysis-by-modelling, and forecasting)

(0.5 min)


Q. "Rate-Time" Plot: log(qo) versus t? (original purpose?)A. Base "performance" plot for PA. (originally used for taxation...)

History: Production Analysis (PA) — q(t)—

From

: Fet

kovi

ch, M

.J.:

"Dec

line

Cur

ve A

naly

sis

Usi

ng T

ype

Cur

ves,

" JP

T(J

une

1980

) 106

5-10

77.

(1 min)

Loss Ratio:

Loss Ratio Derivative:

dtdqq

Da

/1

−≡≡

[ ] ⎥⎦

⎤⎢⎣

⎡−≡⎥⎦

⎤⎢⎣⎡≡≡

dtdqq

dtd

Ddtda

dtdb

/1

—Fr

om: A

rps,

J.J

: "A

naly

sis

of D

eclin

e C

urve

s,"

Tran

s., A

IME

(194

5) 1

60, 2

28-2

47. (

Loss

ratio

n an

d Lo

ss R

atio

Der

ivat

ive)


Q. What is an Estimated Ultimate Recovery (or EUR) plot?A. Plot q(t) vs. Np, extrapolate to zero rate using a straight line ((EUR)exp).

History: Production Analysis (PA) — (EUR)exp—

From

: Fet

kovi

ch, M

.J.:

"Dec

line

Cur

ve A

naly

sis

Usi

ng T

ype

Cur

ves,

" JP

T(J

une

1980

) 106

5-10

77.

(1 min)


Q. What is the "Fetkovich" Decline Type Curve, and how is it used?A. A composite of analytical (pwf=con) and empirical (Arps) solutions —

used as a "type curve" (data overlay) to estimate reservoir properties.

History: Production Analysis (PA) — Fetkovich— From: Fetkovich, M.J.:

"Decline Curve AnalysisUsing Type Curves,"JPT (June 1980) 1065-1077.

Variables for the Fetkovich Decline Type Curve

swwa

wae

wfiDd

wae

wewt

Dd

err

rrB.

ppkhtqq

rr

rrrc

kt.t

−=

⎥⎥⎦

⎤

⎢⎢⎣

⎡−⎥

⎦

⎤⎢⎣

⎡

−=

⎥⎥⎦

⎤

⎢⎢⎣

⎡−⎥

⎦

⎤⎢⎣

⎡⎥⎥

⎦

⎤

⎢⎢

⎣

⎡−⎥

⎦

⎤⎢⎣

⎡=

21ln 2141

)( )(

21ln 1

21

1 006330 22

μ

φμ

Exponential model:

Hyperbolic model:

)exp( tDqq ii −=

)1()(1 b/i

itbD

qq

+=

(1 min)

b-valuesb=0: pwf = constantb=1: qo = constant (qo/Δp formulation).b>1: transient flowor external drive energy.


Q. What is the "Carter" Decline Type Curve, and how is it used?A. A numerically-generated gas rate solution (pwf=con) — used as a

"type curve" (data overlay) to estimate reservoir properties.

History: Production Analysis (PA) — Carter—

From

: Car

ter,

R.D

.: "T

ype

Cur

ves

for F

inite

Rad

ial a

nd

linea

r Gas

Flo

w S

yste

ms:

Con

stan

t Ter

min

al P

ress

ure

Cas

e,"

SPE

J(O

ctob

er 1

985)

719

-728

.

Variables for the Carter Decline Type Curve

swwa

wae

gigi

wfiDd

wae

wewtigi

Dd

err

rrB.

ppkhtqq

rr

rrrc

kt.t

−=

⎥⎥⎦

⎤

⎢⎢⎣

⎡−⎥

⎦

⎤⎢⎣

⎡

−=

⎥⎥⎦

⎤

⎢⎢⎣

⎡−⎥

⎦

⎤⎢⎣

⎡⎥⎥

⎦

⎤

⎢⎢

⎣

⎡−⎥

⎦

⎤⎢⎣

⎡=

21ln 2141

)( )(

21ln 1

21

1 006330 22

μ

φμ

(0.5 min)


[ ] 0

1i,oid,ooi,o q

dtdtqdtq

t

tq == ∫

History: Palacio Type Curve (Con. pwf case)

Q. Enhancement of the functions on the original Fetkovich type curve?A. "Palacio" type curve uses auxiliary rate functions (better resolution).

(1 min)


0

1 ⎥⎥⎦

⎤

⎢⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡Δ

=⎥⎦

⎤⎢⎣

⎡Δ⎥

⎦

⎤⎢⎣

⎡Δ

=⎥⎦

⎤⎢⎣

⎡Δ

= ∫i

o

id

oo

i

oo

ppq

tddt

pq

tdpqt

tpq

qN

t

History: Doublet Type Curve (Con. Rate Eq.)

Q. Type curve solution for variable-rate/variable pressure case?A. "Doublet" type curve uses material balance time function.

(1 min)


Modern PA: Orientation

"Modern production analysis (PA) is a mature and functional process — but we have to recognize that these methods may make us overconfident in our abilities to diagnose, interpret, and analyze a particular field data case."

Blasingame

Q. What are the major advances in PA?A. Various "advances" — see below:

Variable q/variable pwf analysis methods.Auxiliary plotting functions to improve analysis.

(0.5 min)


Modern PA: Material Balance Time (Application)

Q. Application of material balance time?A. Requires pressure and rate histories (accurate rates essential).

tmbpq

tmbqp

qN

tpssopsso

opssopsso

oo

p

,,,,

1 +

=Δ

+=Δ

=

(1 min)

]/ [ op qNt =

]/[ pqo Δ

]/[ oqpΔ


Modern PA: Auxiliary Plotting Fcns (Appl. 1)

Q. Application 1 — What is the "Normalized Productivity Index" plot?A. Pressure drop auxiliary functions versus material balance time.

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡Δ=⎥

⎦

⎤⎢⎣

⎡Δ⎥⎦

⎤⎢⎣

⎡Δ=⎥

⎦

⎤⎢⎣

⎡Δ⎥⎦

⎤⎢⎣

⎡Δ=⎥

⎦

⎤⎢⎣

⎡Δ= ∫

ioidooioodoo

pqp

tddt

qptd

qpt

tqp

qp

tddt

qp

qN

t 0

1

(1 min)

]/ [ op qNt =

]/[ oqpΔ

ioqp ]/[Δ

doqp ]/[Δ

idoqp ]/[Δ


Modern PA: Normalized Productivity Index Plot

Q. What is the "Normalized Productivity Index" plot (and how is it used)?A. This is pressure transient analysis (PTA) analog analysis plot.

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡Δ=⎥

⎦

⎤⎢⎣

⎡Δ⎥⎦

⎤⎢⎣

⎡Δ=⎥

⎦

⎤⎢⎣

⎡Δ= ∫

ioidooioo

pqp

tddt

qptd

qpt

tqp

qN

t 0

1

(2 min)


Variable-rate case:

Variable pressure drop case:

∑ −−==

−n

jj,DDcp,Dj,wfi ttqpp

Bkh

.q

11)( )(

21411

μ

∑ −−−==

−−n

jj,DDcr,sDjji ttpqq

khB.pp

111 )( )(2141 μ

Modern PA: Analysis-by-Modelling

Q. What is "Analysis-by-Modelling?"A. Interactive (dynamic) analysis using a specified reservoir model.

Constant Rate Solution

Constant Pressure Solution

Approach:1. ASSEMBLE: Time-pressure-rate (TPR) data.2. PERFORM: Quality control (particularly on pressure data).3. ESTABLISH: Initial reservoir model using normalized PI/Blasingame plots.4. GENERATE: Rate data + model → pwf(t); pressure data + model → q(t)5. GENERATE: Forecast of production and/or pressure performance.

(1 min)


Modern PA: Analysis-by-Modelling (Oil Case)

Q. What is the analysis procedure for an oil case?A. Assemble TPR data, check data, initialize model, refine, forecast.

"Base Data" Plot:

"Data Check" Plot:

(0.5 min)

Step 1: DataReview


Modern PA: Analysis-by-Modelling (Oil Case)"Normalized PI" Plot:

"Blasingame" Plot:

Q. Behavior of "normalized PI" and "Blasingame" plots for this case?A. Both plots perform EXTREMELY well → driven by data quality.

(0.5 min)

Step 2: Initial Analysis


Modern PA: Analysis-by-Modelling (Oil Case)

Q. Performance of final model match? (i.e., rate and pressure functions)A. Extraordinary agreement of model and data → data quality ...

(0.5 min)

Step

3: H

isto

ry M

atch


Modern PA: Analysis-by-Modelling (Gas Case)

Q. Analysis-by-modelling for gas cases?A. Same general procedure...

"Base Data" Plot:

"Data Check" Plot:

(0.5 min)

Step 1: DataReview



Q. Behavior of "normalized PI" and "Blasingame" plots for this case?A. Both plots perform VERY well → data quality.

"Normalized Productivity Index" Plot: (Gas)

"Blasingame" Plot: (Gas)

(0.5 min)

Step 2: Initial Analysis



Q. How well can a gas case be modeled?A. Depends on the data — can be excellent...

(0.5 min)

Step

3: H

isto

ry M

atch



Q. Analysis of individual pressure transient tests?A. Should be easy — very careful data acquisition is required.

"PTA Summary" Plot:

"History Match" Plot:

(0.5 min)

Step 4: Compare Analyses

(if possible)


Summary: Production Analysis (PA)

"The future looks familiar ... We should be able to perform continuous reservoir monitoring using production analysis (PA). The theory and tools are well-established — the trick is vigilant data acquisition and quality control"

Blasingame

Q. Status check for PA?A. Theory, tools, future of PA summarized below:

PA Theory? (variable q/variable pwf analysis methods proven)PA Tools? (software products are robust and easy to use)PA Future? (better acquisition, numerical models, continuous analysis)

(0.5 min)


Current Assessment: Production Analysis (PA)

"Technology ... is a queer thing. It brings you great gifts in one hand, and it stabs you in the back with the other."

C.P. Snow (1905-1980)

Discussion: Current Assessment — Production Analysis (PA)Analysis? (Very good tools for PA and PTA (incremental improvements))Modelling? (Analytical modelling is sufficient, numerical modelling evolving)Data Issues? (Improvement in data handling (good/bad data, large volumes))Data Acquisition? (Lack of innovation in testing/monitoring methodologies)Integration? (Breakthrough to integrate PA/PTA results with other data)

(0.5 min)


Reservoir Engineering Model●Works 95+ percent of the time...●Why? Pressure and volume

averaging of reservoir properties.●When does it not work? High

contrast in reservoir properties.

Current Assessment: PA Reality Check—

From

: Sim

ulat

or P

aram

eter

Ass

ignm

ent a

nd th

e Pr

oble

m

of S

calin

g in

Res

ervo

ir En

gine

erin

g—

Hal

ders

on (1

986)

.

Q. What is the "reality check" with regard to PA?A. IT IS JUST TIME-PRESSURE-RATE DATA — don't expect a miracle...

Reservoir scale issues? (petrophysical data, PTA, PA, seismic data, etc.)Results from PTA/PA? ("reservoir-scale" flow character)Key to success? (high precision/frequency reservoir performance data)

(1 min)

Actual Reservoir Model●Complex geology.●Complex fluid behavior.●Poor lateral (and vertical) continuity.


— From: Simulator Parameter Assignment andthe Problem of Scaling in ReservoirEngineering — Halderson (1986).

— From: How Heterogeneity AffectsOil Recovery — Weber (1986).

— Crossplot: ko (PA and PTA) vs. klog mean— Santa Barbara Field (Venezuela)..

Current Assessment: Future Work in PTA/PA

Q. What are the prospects for PTA/PA?A. Data quality/frequency → reservoir characterization:

Additional reservoir/well models. (elliptical flow, moving boundary, ...)Reservoir scaling for PTA/PA. (scaling of petrophysical data?)Handling poor quality rate/pressure data. (major issue at present)Continuously measured pwf data. (this is coming ... high frequency rates?)Multiple well analysis (integration). (analytical (material balance)/models)Coupling of analysis/interpretation (3D/3P models). (over-determined case)

(1 min)



Performance-Based Reservoir Characterization –State-of-the-TechnologyEnd of Presentation

Thomas A. Blasingame, Texas A&M U.Department of Petroleum Engineering

Texas A&M UniversityCollege Station, TX 77843-3116

+1.979.845.2292 — [email protected] materials located at:

link → http://www.pe.tamu.edu/blasingame/data/folder → z_SPE_DL


SPE DISTINGUISHED LECTURER SERIESis funded principally

through a grant of the

SPE FOUNDATIONThe Society gratefully acknowledges

those companies that support the programby allowing their professionals

to participate as Lecturers.

And special thanks to The American Institute of Mining, Metallurgical,and Petroleum Engineers (AIME) for their contribution to the program.



Selected References: Production Data Analysis

(Appendix)

References — Production Data Analysis:1. Lewis, J.O., and Beal, C.H.: "Some New Methods for Estimating the Future Production of Oil Wells," Trans. AIME (1918) 59, 492-525.2. Manual for The Oil and Gas Industry Under The Revenue Act of 1918, Treasury Department — United States Internal Revenue Service (1919).3. Cutler, W.W., Jr.: Estimation of Underground Oil Reserves by Oil-Well Production Curves, Department of the Interior, U.S. Bureau Of Mines Bulletin 228 (1924).4. Roeser, H.M.: "Determining the Constants of Oil-Production Decline Curves," Trans AIME (1925) 71, 1315-1321.5. Larkey, C.S.: "Mathematical Determination of Production Decline Curves," Trans AIME (1925) 71, 1322-23.6. Johnson, R.H. and Bollens, A.L.: "The Loss Ratio Method of Extrapolating Oil Well Decline Curves," Trans. AIME (1927) 77, 771.7. Lindsly, B.E., and Berwald, W.B.: Effect of Vacuum on Oil Wells, U.S. Department of Commerce, Bureau of Mines, Bulletin 322 (1930).8. Allen, R.E.: "Control of California Oil Curtailment," Trans AIME (1931) 92, 47-66.9. Rawlins, E. L. and M. A. Schellhardt: Backpressure Data on Natural Gas Wells and Their Application To Production Practices, Monograph 7, U.S. Bureau of Mines, Washington, DC, (1936).

10. Arps J.J.: "Analysis of Decline Curves," Trans. AIME (1945) 160, 228-247. 11. Gurley, J.: "A Productivity and Economic Projection Method — Ohio Clinton Sand Gas Wells," JPT (Nov. 1963) 1183-1188.12. Slider, H.C.: "A Simplified Method of Hyperbolic Decline Curve Analysis," JPT (Mar. 1968) 235-236.13. Stewart, P.R.: "Low-Permeability Gas Well Performance at Constant Pressure," JPT (Sept. 1970) 1149-1156.14. Gentry, R.W.: "Decline-Curve Analysis," JPT (Jan. 1972) 38-41.15. Gringarten, A.C.: "Reservoir Limits Testing for Fractured Wells," paper SPE 7452 presented at the 1978 SPE Annual Technical Conference and Exhibition, Houston, TX., 1-3 October 1978.16. Fetkovich, M.J.: "Decline Curve Analysis Using Type Curves," JPT (March 1980) 1065-1077. 17. Nind, T.E.W.: Principles of Oil Well Production, McGraw-Hill Book Company, 2nd Ed., 1981, 31-44. 18. Carter, R.D.: "Type Curves for Finite Radial and linear Gas Flow Systems: Constant Terminal Pressure Case," SPEJ (October 1985) 719-728.19. Fraim, M.L., Lee, W.J., and Gatens, J.M., III: "Advanced Decline Curve Analysis Using Normalized-Time and Type Curves for Vertically Fractured Wells," paper SPE 15524 presented at the 1986

SPE Annual Technical Conference and Exhibition, New Orleans, LA, 05-08 October 1986.20. Fetkovich, M.J., Vienot, M.E., Bradley and M.D., Kiesow, U.G.: "Decline Curve Analysis Using Type Curves – Case Histories," SPEFE (Dec. 1987) 637-656.21. McCray, T.L.: Reservoir Analysis Using Production Decline Data and Adjusted Time, M.S. Thesis, Texas A&M U., College Station, TX (1990).22. Palacio, J.C. and Blasingame, T.A.: "Decline Curve Analysis Using Type Curves — Analysis of Gas Well Production Data," paper SPE 25909 presented at the 1993 Joint Rocky Mountain

Regional/Low Permeability Reservoirs Symposium, Denver, CO, 26-28 April 1993.23. Doublet, L.E., Pande, P.K., McCollum, T.J., and Blasingame, T.A.: "Decline Curve Analysis Using Type Curves — Analysis of Oil Well Production Data Using Material Balance Time: Application

to Field Cases," paper SPE 28688 presented at the 1994 Petroleum Conference and Exhibition of Mexico held in Veracruz, Mexico, 10-13 October 1994.24. Shih, M.-Y. and Blasingame, T.A.: "Decline Curve Analysis Using Type Curves: Horizontal Wells," paper SPE 29572 presented at the 1995 Joint Rocky Mountain Regional/Low Permeability

Reservoirs Symposium, Denver, CO, 20-22 March, 1995.25. Doublet, L.E. and Blasingame, T.A.: "Evaluation of Injection Well Performance Using Decline Type Curves," paper SPE 35205 presented at the 1996 SPE Permian Basin Oil and Gas Recovery

Conference, Midland, TX, 27-29 March 1996.26. Crafton, J. W.: "Oil and Gas Well Evaluation Using the Reciprocal Productivity Index Method," paper SPE 37409 presented at the 1997 SPE Production Operations Symposium, held in Oklahoma

City, Oklahoma, 09-11 March 1997.27. Agarwal, R.G., Gardner, D.C., Kleinsteiber, S.W., and Fussell, D.D.: "Analyzing Well Production Data Using Combined Type Curve and Decline Curve Analysis Concepts," paper SPE 49222

prepared for presentation at the 1998 SPE ATCE, New Orleans, LA, 27-30 September 1998.28. Marhaendrajana, T. and Blasingame, T.A.: "Decline Curve Analysis Using Type Curves — Evaluation of Well Performance Behavior in a Multiwell Reservoir System," paper SPE 71514 presented

at the 2001 Annual SPE Technical Conference and Exhibition, New Orleans, 30 September-03 October 2001.29. Araya, A. and Ozkan, E.: "An Account of Decline-Type-Curve Analysis of Vertical, Fractured, and Horizontal Well Production Data," paper SPE 77690 presented at the SPE Annual Technical

Conference and Exhibition held in San Antonio, Texas, 29 September-02 October 2002.30. Pratikno, H., Rushing, J.A., and Blasingame, T.A.: "Decline Curve Analysis Using Type Curves: Fractured Wells," paper SPE 84287 presented at the 2003 Annual SPE Technical Conference and

Exhibition, Denver, CO., 05-08 October 2003.31. Mattar, L. and Anderson, D.: "A Systematic and Comprehensive Methodology for Advanced Analysis of Production Data," paper SPE 84472 presented at the SPE Annual Technical Conference

and Exhibition held in Denver, Colorado, U.S.A., 05-08 October 2003.32. Anderson, D. and Mattar, L.: "Practical Diagnostics Using Production Data and Flowing Pressures," paper SPE 89939 presented at the SPE Annual Technical Conference and Exhibition held in

Houston, Texas, U.S.A., 26-29 September 2004.33. Fuentes-Cruz, G., Camacho-Velázquez, R., and Vásquez-Cruz, M. : "Pressure Transient and Decline Curve Behaviors for Partially Penetrating Wells Completed in Naturally Fractured-Vuggy

Reservoirs, paper SPE 92116 presented at the 2004 SPE International Petroleum Conference in Mexico, Puebla, Mexico, 08-09 November 2004.


Selected Vendors: PA Software

(Appendix)

Vendor A: FeketeProduct: RTAContact: Ed Ferguson ([email protected])web: www.fekete.com

Vendor B: Kappa EngineeringProduct: TopazeContact: Kevin Siggery ([email protected])web: www.kappaeng.com

Vendor C: Weatherford/eProduction SolutionsProduct: PanSystemContact: Carol Marini ([email protected])web: www.ep-solutions.com


Simple Rules for Life:Righty-tighty — lefty-loosey solves most problems in life.You can learn a lot from a Chihuahua (no fear, all love).Don't mow the grass until the city tells you to.Leadership is not defined by vision, strength, integrity, or courage — JUST PASSION.If you have to herd cats, then be a rat.If you have to hold yourself out as an example, then make sure to be a bad one (Mark Twain).

Important Rules for Life:Always work harder than those you work for.Never own anything that eats while you sleep.Never own anything that needs repainting.

Rules for Life: Blasingame

"An empty stomach is not a good political advisor — moral — know your convictions, but take care of yourself as well"

Mahatma Gandhi (+ Blasingame)

(Appendix)


Mathematics:(for reservoir engineering)

1.Cheat (approximate, trun-cate, etc.). (except for material balance)

2.Take the Derivative.3.Take the Integral.4.Take the Laplace Transform.5.Go back to Rule 1 (Cheat).

Favorite Numbers: 0, 1, ∞.

(What else do we need?)

Rules for Mathematics: Blasingame

(Appendix)

Documents

Q. - Harold Vance Department of Petroleum Engineering - Texas