PETE 689 (02C) — Pressure Transient Testing Slide — 1(04 December 2002)

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

Texas A&M UniversityCollege Station, TX 77843-3116

(979) 845-2292 — t-blasingame@tamu.edu

(Formation Evaluation and the Analys is of Reservoir Performance)

Modu le for:Analysis of Reservoir Performance

Pressure Transient Testing

PETE 689 (02C) — Pressure Transient Testing Slide — 2(04 December 2002)

� Orientation — This modu le focuses on familiari-zation with deliverabili ty t ests and t he analys isand interpretation pressure transient test d ata.The following issues must be clear: test design,data acquisition/data quali ty control, and testexecution are crit ical activit ies.

� Deliverabili ty Testing:� "4-point" tests are appropriate (analyze as well tes ts).� Isochronal/modified isochronal testing is diff icult.

� Pressure Transient Test Analys is/Interpretation:� Conventional analysis — specialized plots.� Model identification — type curves, simulation, etc.� Test design — simplicity is the key.

Pressure Transient Testing

PETE 689 (02C) — Pressure Transient Testing Slide — 3(04 December 2002)

Deliverabili ty Testing — Basics

a. "Standard" 4-point test deliverabili ty test — notethat the rates increase (to protect the reservoir).

b. " Isochronal" test sequence — note that each"buildup" is required to achieve p i.

c. Modified " Isochronal" test sequence — note thateach "buildup" is not required to achieve p i.

d. Governing equations for "deliverabili ty" testanalys is/interpretation.

PETE 689 (02C) — Pressure Transient Testing Slide — 4(04 December 2002)

Deliverabili ty Testing — Orientation

a. Basic "pressure-squared" relation that is pre-sumed to describe gas flow — analogous formcan be derived from steady-state flow theory(Darcy 's law).

b."Rate-squared" (or velocity-squared) formula-tion — analogous form can be derived fromsteady-state flow theory (Forchheimer Eq.).

d. Modified "deliverabili ty" plot — note that bqsc2

must be known (... need alternative approach).

c.Traditional "deliverabili ty" plot — probablyderived from empirical plotting of data.

PETE 689 (02C) — Pressure Transient Testing Slide — 5(04 December 2002)

Deliverabili ty Testing — 4-Point Tests

a.Basic deliverabili ty test analys is — note thedifference in the simpli fied and "LIT" cases.

b. "Standard" 4-point test deliverabili ty test — notethat the rates increase (to protect the reservoir).

�Discuss ion:�The value "value" of deliverabili ty

tests is in the process — the datacan be be more effectively analyz-ed as "well test data" than asdeliverabili ty data. However, deli -verabili ty analys is can serve as aquali ty control (data checking).

PETE 689 (02C) — Pressure Transient Testing Slide — 6(04 December 2002)

Deliverabili ty Testing — Isochronal Tests

Isochronal Test Analys is — Note the multiple trend s .

PETE 689 (02C) — Pressure Transient Testing Slide — 7(04 December 2002)

Well Test Analys is — Multirate Testing

a. Multirate (4-point) rate sequence (note pressurematch (solid trend through the data).

b. Log-log "summary plot" — note good agreementin comparison of data and model.

c. Results summary — note that non-Darcy flow,changing wellbore storage, and an infin ite-acting reservoir sys tem were considered in thisanalys is.

PETE 689 (02C) — Pressure Transient Testing Slide — 8(04 December 2002)

Well Test Analys is — "Well Interference"

a. "Well Interference" plot — note the linear trendthrough the data functions (confirms interference) .

b. Log-log "summary plot" — note the corrected anduncorrected data (well i nterference).

c. Horner semilog plot — note the two semilogtrends confirm the radial composite model.

�Discuss ion:�"Well i nterference" is much more

common than previously thought— and we must recognize thecharacteristic behavior on eachplot:–Log-log plot (b)–Semilog plot (c)–Specialized plot (a)

PETE 689 (02C) — Pressure Transient Testing Slide — 9(04 December 2002)

Well Test Analys is — Basic Plots

a. Log-log "preliminary analysis"plot — wellbore storage andradial flow (Cs, k).

b. Cartesian "early-time" plot —used to analyze wellborestorage (p0, Cs).

c. Semilog "middle-time" plot —used to analyze radial flowbehavior (k, s).

d. Horner "middle-time" plot —used to analyze radial flowbehavior (k, s, p*).

f. Log-log "summary" plot —summary of all analysis (Cs, k,s, A, etc).

e. Cartesian "Arps" plot — usedto estimate average reservoirpressure.

PETE 689 (02C) — Pressure Transient Testing Slide — 10(04 December 2002)

Well Test Analys is — Basic Plots (1)

� Example: "Preliminary Analys is" (log-log).

PETE 689 (02C) — Pressure Transient Testing Slide — 11(04 December 2002)

Well Test Analys is — Basic Plots (2)

� Example: "Horner Semilog Analys is" (semilog).

PETE 689 (02C) — Pressure Transient Testing Slide — 12(04 December 2002)

Well Test Analys is — Basic Plots (3)

� Example: "Analys is Summary Plot" (log-log).

PETE 689 (02C) — Pressure Transient Testing Slide — 13(04 December 2002)

�Given data — Lee text (1st edition),Example 2.2.

Well Test Analys is — Work Relations

�Working relations — Lee text (1stedition), Example 2.2).

PETE 689 (02C) — Pressure Transient Testing Slide — 14(04 December 2002)

Well Test Analysis — WBS Type Curves

a. Type Curve: Radial flow withwellbore storage and skineffects (pD, pDd).

d. Type Curve: Radial flow withwellbore storage and skineffects (pDi, pDid).

b. Type Curve: Radial flow withwellbore storage and skineffects (pD, pDd, pDr1).

e. Type Curve: Radial flow withwellbore storage and skineffects (pDi, pDid, pDir1).

f. Type Curve: Radial flow withwellbore storage and skineffects (pDi, pDir2).

c. Type Curve: Radial flow withwellbore storage and skineffects (pD, pDdd).

PETE 689 (02C) — Pressure Transient Testing Slide — 15(04 December 2002)

Well Test Analysis — WBS Type Curves (1)

� Type Curve: "Gringarten-Bourdet" (pD, pDd).

PETE 689 (02C) — Pressure Transient Testing Slide — 16(04 December 2002)

Well Test Analysis — WBS Type Curves (2)

� Type Curve: "Second Derivative) (pD, pDdd).

PETE 689 (02C) — Pressure Transient Testing Slide — 17(04 December 2002)

Well Test Analysis — WBS Type Curves (3)

� Type Curve: " Integral Functions" (pDi, pDid).

PETE 689 (02C) — Pressure Transient Testing Slide — 18(04 December 2002)

Well Test Analys is — Bound ed Reservoir

a. Type Curve for sealing faults (pDd). b. Type Curve for conductive (leaky ) faults (pDd).

c. Type Curve for pressure buildup test in aclosed rectangular reservoir (pDd).

d. Type Curve for pressure buildup test in aclosed rectangular reservoir (pDid).

PETE 689 (02C) — Pressure Transient Testing Slide — 19(04 December 2002)

Well Test Analys is — Bound ed Reservoir (1)

� Type Curve: "Sealing Faults" (pDd).

PETE 689 (02C) — Pressure Transient Testing Slide — 20(04 December 2002)

Well Test Analys is — Bound ed Reservoir (2)

� Type Curve: "Closed Reservoir" (Buildup Only) (pDd).

PETE 689 (02C) — Pressure Transient Testing Slide — 21(04 December 2002)

Well Test Analys is — Composite Systems

a. Composite Reservoir (ηr=1x10-3). b. Composite Reservoir (ηr=1x10-2).

d. Composite Reservoir (ηr=1x100). e. Composite Reservoir (all ηr cases).

c. Composite Reservoir (ηr=1x10-1).

PETE 689 (02C) — Pressure Transient Testing Slide — 22(04 December 2002)

Well Test Analys is — Composite Systems (1)

� Type Curve: all ηr cases (Tang-Brigham).

PETE 689 (02C) — Pressure Transient Testing Slide — 23(04 December 2002)

Well Test Analys is — Fractured Wells

a. Type Curve: CfD= various,no CDf cases.

c. Type Curve: CfD=2, CDf = various.

d. Type Curve: CfD=5, CDf = various. f. Type Curve: CfD=1x103,CDf = various.

b. Type Curve: CfD=1, CDf = various.

e. Type Curve: CfD=10, CDf = various.

PETE 689 (02C) — Pressure Transient Testing Slide — 24(04 December 2002)

Well Test Analys is — Fractured Wells (1)

� Type Curve: Various CfD (Cinco-Samaniego).

PETE 689 (02C) — Pressure Transient Testing Slide — 25(04 December 2002)

Well Test Analys is — Fractured Wells (2)

� "Pseudoradial flow" sk in factor correlation for afractured well (Cinco-Samaniego).

PETE 689 (02C) — Pressure Transient Testing Slide — 26(04 December 2002)

Well Test Analys is — Fractured Wells (3)

� Type Curve: CfD=2, various CDf cases.

PETE 689 (02C) — Pressure Transient Testing Slide — 27(04 December 2002)

Well Test Analys is — Fractured Wells (4)

� Type Curve: CfD=1x103, various CDf cases.

PETE 689 (02C) — Pressure Transient Testing Slide — 28(04 December 2002)

Well Test Analys is — Dual Porosity Reservoirs

a. Type Curve: ωωωω,λλλλ= various,pss interporosity flow.

d. Type Curve: ωωωω,λλλλ= various, tran-sient interporosity flow.

f. Type Curve: λλλλCD= 1x10-4,transient interporosity flow.

b. Type Curve: λλλλCD= 1x10-1, pssinterporosity flow.

c. Type Curve: λλλλCD= 1x10-4, pssinterporosity flow.

e. Type Curve: λλλλCD= 1x10-1,transient interporosity flow.

PETE 689 (02C) — Pressure Transient Testing Slide — 29(04 December 2002)

Well Test Analys is — Dual Porosity Reservoirs (1)

� Type Curve: Pseudosteady-State InterporosityFlow (Onur, et al format).

PETE 689 (02C) — Pressure Transient Testing Slide — 30(04 December 2002)

Well Test Analys is — Dual Porosity Reservoirs (2)

� Type Curve: Transient Interporosity Flow (Onur,et al format).

PETE 689 (02C) — Pressure Transient Testing Slide — 31(04 December 2002)

Well Test Analys is — Dual Porosity Reservoirs (3)

� Type Curve: λλλλCD= 1x10-4, pss interporosity flow.

PETE 689 (02C) — Pressure Transient Testing Slide — 32(04 December 2002)

Well Test Analys is — Dual Porosity Reservoirs (4)

� Type Curve: λλλλCD= 1x10-4, transient interporosity flow.

PETE 689 (02C) — Pressure Transient Testing Slide — 33(04 December 2002)

�From: Simulator Parameter Ass ignmentand the Problem of Scaling in ReservoirEngineering — Halderson (1986).

� Pressure transient analys is"sees" the reservoir as a volume-averaged set of properties.

� New solutions/models will alsohave this view of t he reservoir —but, quantifying heterogeneitymay (or may not) be poss ible bythe analys is of pressure transienttest data.

� Scaling will remain a major issue— regardless of the mechanismused to analyze reservoirperformance.

Well Test Analys is — Scaling

PETE 689 (02C) — Pressure Transient Testing Slide — 34(04 December 2002)

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

Texas A&M UniversityCollege Station, TX 77843-3116

(979) 845-2292 — t-blasingame@tamu.edu

(Formation Evaluation and the Analys is of Reservoir Performance)

Modu le for:Analysis of Reservoir Performance

Pressure Transient Testing

End of Presentation