Modeling and Simulation of Naturally Fractured Reservoirs

Prepared for the EORI Joint EOR Commission & Technical Advisory Board Meeting

Shaochang WoEORI, University of Wyoming

Laramie, July 23, 2009

2007 Average Water Cut from Wyoming Oil Producing Reservoirs is 96.9%

3

Idealization of A NFR System(Warren and Root 1963)

4

Dual Porosity/Permeability Model of Single Phase Flow

tp

Cpk f

tffff

∂∂

=−∇•∇ ϕτμ

)(

tpCpk m

tmmmm

∂∂

=+∇•∇ ϕτμ

)(

)( mfm ppk

−=μ

στ

⎥⎥⎦

⎤

⎢⎢⎣

⎡++= 2223/1)( z

mz

y

my

x

mx

mzmymx Lk

Lk

Lk

kkkSσ

Fracture:

Matrix:

Transfer Function:

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Some of Proposed Shape Factor Constants for Single-Phase Dual-Porosity Model

1 set of fractures 2 sets of fractures 3 sets of fractures

Warren & Root (1963) 12 32 60

Kazemi et al. (1976) 4 8 12

Coats (1989) 8 16 24

Lim & Aziz (1995) π2 (9.87) 2π2 (19.74) 3π2 (29.61)

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7

8

9

Fluid ExpansionGravity DrainageImbibitionRelative PermeabilityMolecular Diffusion

Transfer Function in Multiphase Flow(i.e. Oil, Water, & Gas Phases)

Transfer function of oil-water 2-phase flow with gravity effect

(Kazemi and Gilman 1993)

)}()(){( wmwfwz

mfw

rwmw hhppkk

−+−= γσσ

μστ

Working on Tensleep Reservoirs

Reservoir data from Mahoney Dome, Hatfield, East Salt Creek, and Teapot Dome fieldsMatrix and fracture characterization

Peigui Yin, John Lorenz, Scott CooperReservoir rock wettability analysis

Sheena Xie, Norman MorrowStudents

Michael Presho, Matthew Johnson

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Petrel Fracture Modeling Workflow

Well data DataAnalysis

ModelParameters

CreateDFN

Upscale & Simulate

12

Petrel, Schlumberger

Conductive and Storage Fractures

Open Fracture Size

Num

ber o

f Fra

ctur

es

Conductive Fractures (<10%)

Storage Fractures

Proposed Works with A Focus on Tensleep Reservoirs

Continuing the work on fracture characterizationResearch on transfer function for multiphase flowRegression method to estimate the distribution of conductive open fractures from matching well production/injection historyBenchmark cases based on actual field dataSimulation of CO2 flooding with dual porosity/permeability models

Potential Application of Fly Ash in Injection Profile Control and EOR Flooding

Prepared for the EORI Joint EOR Commission & Technical Advisory Board Meeting

Shaochang Wo and Peigui YinEORI, UW

Sheena Xina Xie and Norman MorrowChemical & Petroleum Engineering Dept., UW

Laramie, July 23, 2009

16

100 μm

Mechanisms of Particle Capture by Porous Media

STRAINING DEPOSITSURFACE CAKE

Big Particles Medium Particles Small Particles

18

Fractures in Tensleep Sandstone

Outcrop Core

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20

21

100 μm

22

Characteristics of Fly Ash Particles

Collected from the chimneys of coal-fired power plants by electrostatic precipitators or filter bagsGenerally spherical in shapeParticle size: 0.5~300 μmTrue density: 2~2.3 t/m3

Packing density: 550~658 kg/m3

Packing porosity: 60%~75%

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Measurement of Fly Ash True Density

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State Basin Power Plant SiO2 AI2O3 CaO Fe2O3 LOI

WT% WT% WT% WT% WT%

Wyoming GRB Jim Bridger 64.2 15.4 6.39 4.66 0.28Wyoming Overthrust Belt Naughton 56 17.6 11.3 7.64 0.19

Craig 38.8 17.2 22 3.6 5.28Wyoming PRB Dave Johnson 50 21.3 17.3 4.3 1.78

Hayden 41.2 22.4 14 2.1 13.76Wyoming Denver Basin Laramie ‐River (LRP Unit 1) 33.5 17.1 28.6 5.6 0.44Wyoming PRB WyoDak 33.6 19.1 23.5 4 1.63

BCR‐1 54.5 13.7 7 13.5 0.7

Chemical Composition of Collected Fly Ash Samples

Potential Application of Fly Ash in EOR

For Improving Water Injection profileFly ash + polymerFly ash + polymer + bentonite + coagulant

For Use in Combination with CO2 floodingSurfactant floodingSteam flooding

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Measured Viscosities of Polyacrylamide Solution with Wall Creek-2 Brine

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Fly Ash Suspension in Polymer Solution

At 0 hour After 48 hours

Collected ten fly ash samples, including samples from all major Wyoming power plantsPurchased a GilSonic UltraseiverCompleted chemical composition analysis on collected fly ash samples and selected Jim Bridger ash for further lab tests Identified a potential field test site at ROMTCOngoing works on sieve analysis and suspension tests of fly ash in polymer solutionFurther works including lab core flooding tests, modeling of fly ash transport and straining, and design of fly ash injection for the pilot test site

Project Status

30

86

85

16

87

Potential Test Site in Wall Creek-2 at RMOTC