Unconventional ReservoirsFlow modelling challenges

Victor Salazarvictor.salazar@cmgl.ca

November, 2013

Agenda

1. CMG products

2. Unconventional Reservoir Modelling Physics

3. Using CMG’s Reservoir Simulation products to Determine EUR from Limited Data

4. Using CMG’s Reservoir Simulation products to Optimize Well Completion Design & Well Spacing

5. SPE Unconventional Reservoir papers that feature the use of CMG’s Reservoir Simulation products

CMG Software ProductsSuperior physicsSuperior physics

EOR advanced processes leader (+95%)

IMEX Black Oil/Condensate simulator

GEM Equation of State Compositional Simulator

STARS K value compositional, thermal, chemical, geomechanical simulator

Reservoir Numerical Simulators

Phase behavior, PVT modellingWINPROP

Pre & Post ProcessorsBUILDER

RESULTS 3D

RESULTS GRAPH

RESULTS REPORT

Project Manager

ConverterECL 100 IMPORT ASSISTANT

LAUNCHER

Assisted history match, Optimization, Sensitivity and Uncertainty analysis

CMOST

Unconventional reservoirs physics

Diffusion Desorption Fractured system Non-Darcy effects Low porosity/permeability Typical Shale Adsorption Curve

0

100

200

300

400

500

600

700

0 1000 2000 3000 4000

Pressure (psi)G

as

Ad

so

rpti

on

(ft

3/t

on

)Shale

CMG Simulator PhysicsPhysics IMEX GEM

PVT BO, VO, GC, WG EOS

Adsorbed Comp Gas Comp Any Comp

Diffusion No Any Comp

Natural Fracs DP or DK DP or DK

Non-Darcy (turbulent) Flow Yes Yes

Klinkenberg (slip) Flow No Yes

Krel/Pc by Rock Type Yes Yes

Propped Fracs Explicit Grids Explicit Grids

Press-dependent Compaction Yes (& w/ time) Yes (& w/ time)

Stress-dependent Compaction No Yes (w/ GEOMECH)

LS-LR-DK gridding Yes (& w/ time) Yes (& w/ time)

CMG Frac’d Well Modelling History

Microseismic Results

Trend visible in red stagePossible trend visible in blue stage

Possible interaction with pre-existing fractures?

In-situ stress will influence dominant hydraulic fracture orientations

Shmax direction?

Williams-Stroud, Microseismic, 2008

Single Plane Geometry

Complex Geometry

BUILDER can create LS-LR-DK (tartan) grids around fractures

automatically

Propped Frac Gridding is EASY

Varying Propped Frac Properties & SRV Size with CMOST is EASY

Propped Frac PropertiesHalf-length, Width, Perm, Spacing,

Height & Perm GradientStimulated Natural Frac Properties:

Width, Perm

SRV Size & Shape# MS events per gridblock

MS Moment MagnitudeMS Confidence Value

Etc.

Geomechanics Independent

geomechanic grid Hydraulic fracture closure New fractures opening Permeability vs Stress

Crack occurs

D

A

Beginning

C

B

kfmax

kf

σ/fn

kfmin

A27I

C16I

A27I

C16I

3 key Questions about Unconventional Reservoirs

1. How can I determine the EUR with limited data?

2. What is the Optimum Well Completion Design?

3. What is the Optimum Well Spacing?

Physics-based EUR Calculation1. Choose CMG simulator

with required physics

2. Build base model

3. Perform SA & AHM4. Forecast EUR using

best HM models

Engineer builds base model, decides which parameters to allow CMOST to vary, and CMOST does

the rest

Physics-based EUR Calculation

• 4000 ft Eagle Ford “Oil Window” well• 41-stage frac job pumped

• 7 months of production (222 days)• Oil, gas & water rates, and flowing BHP

measured daily

• Task: Determine Oil & Gas EURs• Solution: Match 7 months of history &

Forecast 30 years of future production

Physics-based EUR CalculationKnown Reservoir, Well & Fluid Properties

Property Value UnitDepth at top of reservoir 10,800 feet

Reservoir thickness 150 feetInitial Reservoir Pressure 8,100 psi

Initial Reservoir Temperature 270 FOil Bubble Point Pressure 3010 psi

Oil Gravity 43 APIInitial Solution GOR 950 scf/stb

Lateral Length 4000 feetNumber of Frac Stages Pumped 10

Physics-based EUR CalculationRanges for uncertain reservoir & frac properties

PropertyMin Value

Max Value Unit

Matrix Porosity 0.04 0.10 fractionMatrix Permeability 10 1000 nD

Natural Fracture Effective Porosity 0.0006 0.0006 fractionNatural Fracture Effective Permeability 40 40 nD

Natural Fracture Areal Spacing 50 50 feetPropped Fracture Spacing 100 400 feet

Propped Fracture Half-Length 50 400 feetPropped Fracture Permeability 1 30 D

Swi in Propped & Natural Fractures 0.15 0.45 fraction

Physics-based EUR CalculationKrel, Pc & PV Compaction Assumptions

Property AssumptionsMatrix Krel Corey Functions are sufficient

Natural Fracture Krel Straight Line behaviorPropped Fracture Krel Straight Line behavior

Matrix Pc Can ignore during primary depletionNatural Fracture Pc ZeroPropped Fracture Pc Zero

Matrix PV Compaction Constant CompressibilityNatural Fracture PV Compaction Constant CompressibilityPropped Fracture PV Compaction Changes with Pressure

Physics-based EUR Calculation2D Areal View of Simulation Grid

Physics-based EUR Calculation3D Perspective View of Simulation Grid

Physics-based EUR Calculation

CMOST Assisted HM Optimization Sensitivity and Uncertainty analysis

Physics-based EUR Calculation

MatrixPerm(md)

MatrixPor

(frac)

Nat FracSwi

(frac)

Rock Comp Table #

Prop’dFracXf(ft)

Prop’dFrac

Perm(md)

Prop’dFrac

Spacing(ft)

Prop’dFracSwi

(frac)

0.00001 0.04 0.15 ctype1.inc 50 1000 100 0.15

0.0001 0.06 0.25 ctype2.inc 150 10000 200 0.25

0.0005 0.08 0.35 ctype3.inc 250 20000 300 0.35

0.001 0.1 0.45 ctype4.inc 400 30000 400 0.55

Discrete Values used in Sensitivity Analysis

Physics-based EUR Calculation

0 1000 2000 3000 4000 5000 6000 7000 8000 90000.0001

0.001

0.01

0.1

1

ctype1

ctype2

ctype3

ctype4

Pressure, psia

Per

mea

bil

ity

Mu

ltip

lier

Propped Frac PV Compaction Curves

Physics-based EUR CalculationCumulative Oil Tornado Plot

Physics-based EUR Calculation

Cumulative Water Tornado Plot

MatrixPerm(md)

MatrixPor

(frac)

Nat FracSwi

(frac)

Rock Comp Table #

Prop’dFrac

Xf(ft)

Prop’dFrac Perm(md)

Prop’dFrac

Spacing(ft)

Prop’dFracSwi

(frac)

0.00001 0.04 0.15 ctype1.inc 50 1000 100 0.150.00005 0.05 0.16 ctype2.inc 100 5000 150 0.200.0001 0.06 0.17 ctype3.inc 150 10000 200 0.250.0002 0.07 0.18 ctype4.inc 200 15000 250 0.300.0003 0.08 0.20 250 20000 300 0.350.0004 0.09 0.25 300 25000 350 0.400.0005 0.10 0.30 400 30000 400 0.450.0007 0.350.001 0.40

Physics-based EUR CalculationDiscrete Values used in History-Match

Total Search Space: 6.22 million combinations

Physics-based EUR CalculationHistory-Match Run Progress Plot

Engineer only has to monitor History-Match progress….. so is free to work on other projects!

Physics-based EUR CalculationOil Phase History-Match

Physics-based EUR CalculationGas Phase History-Match

Physics-based EUR CalculationWater Phase History-Match

Physics-based EUR CalculationFlowing BHP History-Match

Physics-based EUR Calculation30-yr Oil EUR using 15 best HM models

Oil EUR (stb)Maximum 724,059Minimum 571,847Average 654,125Median 649,323Std Dev 45,162

Physics-based EUR Calculation30-yr Gas EUR using 15 best HM models

Gas EUR (MMscf)Maximum 981Minimum 851Average 926Median 922Std Dev 44

Time to do Physics-based EUR

TaskTime (hr)

Time/Run (min)

ENGINEER’s time 8 -

100 CMOST SA runs* 2.8 1.7

446 CMOST AHM runs* 8.5 1.1

15 x 30-year forecast runs** 0.6 2.5

TOTAL COMPUTE Time 11.9 -

* 4 simultaneous 4-way parallel IMEX runs on a Dell Precision T5600** Sequential 16-way parallel IMEX runs on a Dell Precision T5600

Physics-based Well Optimization1. Choose CMG simulator

with required physics

2. Build base model

3. Perform SA4. OPT Completion Design5. OPT Well Spacing

Engineer builds base model, decides which parameters to allow CMOST to vary, and CMOST does

the rest

Physics-based Well OptimizationAssumed Reservoir, Well & Fluid Properties

Property DataNatural Fracture Relative Permeability Straight Line data from EUR calc.

Propped Fracture Relative Permeability Straight Line data from EUR calc.Matrix Capillary Pressure Assumed to be zero

Natural Fracture Capillary Pressure Assumed to be zeroPropped Fracture Capillary Pressure Assumed to be zero

Matrix Pore Volume Compaction ConstantNatural Fracture PV Compaction ConstantPropped Fracture PV Compaction “ctype4.inc” from EUR calc.

Physics-based Well Optimization

Assumed Economic Parameters

Economic Parameter Value UnitOil Price 100 $US/bblGas Price 3 $US/Mscf

Well Drilling Cost 3,000,000 $US/wellFrac Cost 250,000 $US/Stage

Forecast Period 30 years

Physics-based Well OptimizationProposed Well Completion/Spacing Options

PropertyMin

ValueMax Value Unit

Proposed Well Spacing128

(5 wells)640

(1 well) acresProposed Well Lateral Length 4000 4000 feet

Proposed Propped Fracture Spacing 200 800 feet

Proposed Propped Fracture Half-Length 50 400 feet

Proposed Propped Fracture Permeability 1 20 D

Physics-based Well OptimizationDiscrete Values used for Completion Optimization

Propped Frac Spacing

(feet)

Propped Frac Permeability

(Darcies)

Propped Frac Half-Length

(feet)

200 1 50300 3 100400 6 200500 9 300600 12 400800 15

18 20

Total Search Space: 240 combinations

Physics-based Well OptimizationOptimization Run Progress Plot

Engineer only has to monitor Optimization progress….. so is free to work on other projects!

Physics-based Well OptimizationOptimum Parameter Histograms

Physics-based Well Optimization

Default-Field-PRO base model_km_0.0005md.irf

Time (Date)

Cu

mu

lativ

e O

il SC

(bb

l)

2015 2020 2025 2030 2035 2040 20450.00e+0

1.00e+6

2.00e+6

3.00e+6

4.00e+6

5.00e+6

Cumulative Oil SC base model_km_0.0005md.irfCumulative Oil SC Base Model_Km_0.0005mD_2wells.irfCumulative Oil SC Base Model_Km_0.0005mD_3wells.irfCumulative Oil SC Base Model_Km_0.0005mD_4wells.irfCumulative Oil SC Base Model_Km_0.0005mD_5wells.irf

Cum Oil after 30 years vs # of Wells

# of WellsNPV

(MMUSD)1 492 973 1454 1915 230

Physics-based Well OptimizationMatrix Pressure @ 30 years with 4 & 5 wells

Time to do Physics-based Well Completion & Spacing

Optimization

Task Time (hr)Time/Run

(min)

ENGINEER’s time 8.0 -

55 CMOST OPT runs* 2.2 1.9

5 IMEX 30-year Forecast runs** 0.85 10.2

TOTAL COMPUTE Time 3.05 -

* 4 simultaneous 4-way parallel IMEX runs on a Dell Precision T5600** 5 Sequential 16-way parallel IMEX runs on a Dell Precision T5600

SPE References

Used GEM to model DFITs and concluded:• Greatly enhances our ability to efficiently design DFIT's for tight shale reservoirs• Shows the validity of the Nolte analysis technique for tight rocks and provides guidelines for the shut-in

time duration required to generate a reasonable estimate of reservoir properties from DFIT pressure response

• Shows that geomechanics-coupled reservoir flow simulation of DFITs can provide estimates of fracture dimensions that compare reasonably with those from more traditional fracture design tools

• Demonstrate that geomechanics-coupled reservoir flow simulation provides an additiona advantage over traditional fracture design tools in that is can numerically model the system response even after fracture closure

• Shows significant fracture tip extension, both vertically and horizontally, for a significant period after the end of the shut-in period

SPE ReferencesSPE 166279

Estimation of Effective Fracture Volume Using Water Flowback and Production Data for Shale Gas WellsAhmad Alhkough (TAMU), Steve McKetta (Southwestern Energy) and Robert Wattenbarger (TAMU)

Used IMEX to model water flowback and long-term production, and concluded:• Used to simulate production of gas and water from a shale gas well• Water production analysis can provide effective fracture volume

estimates, which were confirmed by cumulative water produced, which in turn can evaluate fracture-stimulation treatments.

• Water production analysis can show the pitfalls of ignoring flowback data (i.e. in some cases the time-shift on diagnostic plots changes the apparent flow regime indentification of the early gas production data, as well as water production data, which leads to different (incorrect) interpretation of the fracture/matrix system.

SPE ReferencesURTeC 1575448

Marcellus Well Spacing Optimization – Pilot Data Integration and Dynamic Modeling StudyDeniz Cakici, Chris Dick, Abhijit Mookerjee, Shell Exploration & Production; Ben Stephenson, Shell Canada

Used GEM & CMOST to Match production history

36 E&P Companies are using CMG for Unconventional Reservoir Modelling

• Anadarko• Apache• BG Group• BHP Billiton• Birchcliff• Bonterra• BP• Chesapeake• Chevron• Devon• Encana• Enerplus

• EOG• ExxonMobil• Harvest• Marathon• Matador• Nexen• Noble Energy• PennWest• Perpetual• Petrobakken• Reliance• Rosetta

Resources

• Samson• Sasol• Seven Generations• Shell• Sinopec Daylight• Southwestern Energy• Statoil• Talisman• Taqa North• Total• Vitruvian• XTO

“Physics-based” EUR & Well Optimization

in hoursusing CMG software

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