Download pdf - Perspectives on the Well Performance Analysis and Forecasting in

Dilhan ILK/DeGolyer and MacNaughton

A Presentation in the SPE PRMS Workshop

13 November 2013

Brisbane, AUSTRALIA

Perspectives on the Well Performance Analysis and Forecasting in Unconventional Resources

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North America Shale PlaysSignificant production from shale gas and oil plays in North America

Perspectives on the Well Performance Analysis and Forecasting in Unconventional ResourcesSPE PRMS Workshop -- Brisbane, Australia

Production from Unconvetional ResourcesU.S. Tight oil production by select plays, 2000-2012 (millions of barrels/day)

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(Ref. from Sieminski 2013 (Energy Information Administration))Perspectives on the Well Performance Analysis and Forecasting in Unconventional ResourcesSPE PRMS Workshop -- Brisbane, Australia

Production from Unconventional ResourcesSignificant production growth from liquids-rich plays

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(Ref. from Texas Railroad Commission)

(Ref. McKinsey Global Institute 2013)


Production from Unconventional ResourcesEagle Ford Well Count from Texas Railroad Commission

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January 2013 September 2013

January 2013 ≈ 3,400. September 2013 ≈ 6,400.Perspectives on the Well Performance Analysis and Forecasting in Unconventional ResourcesSPE PRMS Workshop -- Brisbane, Australia

Production from Unconventional ResourcesFluid flow and storage mechanisms are different in unconventional plays

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Fluid storage in the nanopores, organic matter, adsorbed?

Flow path can be as small as 10-20 molecular diameters


Mineral composition varies widely. Each play is unique.

Decline Curve Analysis — Modified HyperbolicSchematic represents the most common approach to EUR estimation

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(From Tom Blasingame)


Decline Curve Analysis — IssuesSchematic illustrates the uncertainty associated with decline curves

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Possible to fit the data with various "b" values and obtain a wide range for EUR A systematic methodology is critical to obtain a well performance curve instead of

using a single decline curve

102 102

103 103

104 104

105 105

4,00

0

3,80

0

3,60

0

3,40

0

3,20

0

3,00

0

2,80

0

2,60

0

2,40

0

2,20

0

2,00

0

1,80

0

1,60

0

1,40

0

1,20

0

1,00

0

800

600

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2000

Production Time, days

Schematic for Haynesville Shale Gas Well Performance PossibilitiesProduction Rate and Time Plot (Semilog Scale)

Gas

Flo

wra

te, q

g, M

SCF/

D

b = 1.5EUR = 7.81 Bscf

b = 1.0EUR = 6.15 Bscf

b = 0.8EUR = 5.31 Bscf

b = 0EUR = 3.98 Bscf

≈2 years of production data from a Haynesville Shale gas well


Decline Curve Analysis — IssuesNumerical simulation study presents errors associated with decline analysis

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x

yPressure

MonitoringPoint No. 1

PressureMonitoringPoint No. 2

HydraulicFracture

Wellbore

X

X

x

y

x

yPressure

MonitoringPoint No. 1

PressureMonitoringPoint No. 2

HydraulicFracture

Wellbore

X

X

Numerical Model Considers:●Reservoir Layering.●kv/kh ratio.●Fracture Length, xf.●Fracture Conductivity, FcD.Analysis/Validation Approach:●Fit q(t) with Arps' hyperbolic relation.●Compare reserves to model at 30 years.

SPE 109625 (2007)Estimating Reserves in Tight Gas Sands at HP/HTReservoir Conditions: Use and Misuse of an Arps Decline Curve Methodology

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Decline Curve Analysis — New ModelsPower-law exponential relation is a powerful tool to match rate-time data

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●Flow Regimes: (Time-Rate Data)■ Identify diagnostic/characteristic behavior exhibited by data.■ Evaluate D(t) and b(t) continuously (at all points).■ Power-law exp. relation is based on power-law behavior of D-parameter.

dtdqq

dtdb

g

g

/

dtdq

qD g

g

1

D-parameter:

b-parameter:

Basis for decline curve relations:


Decline Curve Analysis: Eagle Ford Oil ExampleEUR is estimated using various methods to yield a range of outcome

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q/Np and time plot Oil rate and time plot

■ All model matches are imposed on data (for oil rates)■ EURPLE = 238 MSTB, EURSE = 237 MSTB, EURLGM = 248 MSTB,

EURMHYP = 334 MSTB, EURDNG = 487 MSTBPerspectives on the Well Performance Analysis and Forecasting in Unconventional ResourcesSPE PRMS Workshop -- Brisbane, Australia

Continuous Estimation of Ultimate RecoveryEUR is calculated continuously and presented as a function of time

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a. Continuous EUR (CEUR) process plots.

b. CEUR hyperbolic, PLE, and q-Gp summary plots.

])(1[/)( )/1( bigi tbDqtgq

]ˆexp[ˆ)( nigi tDtDqtgq

]/[ )( igi DqGpGiDgiqtgq

[hyperbolic]

[PLE]

[qg(t) vs. Gp(t)]


Model-based Production AnalysisObjective of model-based analysis is to honor flow physics in the reservoir

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● Model Parameters: ■ Permeability (k)■ Fracture half-length (xf)■ Fracture conductivity (Fc)■ Drainage area (A)■ Skin factor (s)■ Well length (Lw)■ Number of fractures (nf)

1

2 3


Model-based Production AnalysisObjective of model-based analysis is to honor flow physics in the reservoir

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(1:2)(1:4)

(1:1)

(1:1 Slope — Fracture interference/Depletion (SRV?))

(1:2 Slope — Linear flow/High fracture conductivity)

(1:4 Slope — Low fracture conductivity)

Duration and existence of flow regimes are DIFFERENT for each shale play

EURLF (VERY OPTIMISTIC)

EURDep (CONSERVATIVE ??)

Pseudo-elliptical flow regime (flow from matrix to collection of fractures) might exist after fracture interference.

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1

2
