shale tech coference 2011

7/30/2019 Shale Tech Coference 2011

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Explicit Fracture Modeling OfEagle Ford Shale Gas Condensate

Alpay Erkal and John Blair

knowledge reservoir


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Agenda

Introduction

Shale Gas Modeling Fundamentals

Modeling Approaches Today

Explicit Hydraulic Fracture Modeling Application to Eagle Ford Condensate Window


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Introduction

Natural fractures are generally mineralized

Hydraulic fracture networks are created for

each stage

roppants are p ace n t e ma n a rway angravity effects influence the settlement

Clean-up efficiencies determine productive

volume and surface area


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Shale Gas Modeling Fundamentals

Productive volume is less than the stimulated volume

typically associated with the microseismicinformation

Dual porosity system has very small interporosity

essentially single porosity system

Transient system at all timesnot reflected in underlying mathematical models used

today (Warren & Root)

Mostly free gas so adsorpted gas is not as significant


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Modeling Approach Today

Dual porosity conventional models

Modifications from coal-bed-methaneLangmuir isotherms for adsorption

of the system numerically

sub-discretization of matrix cells; exponentialincrease in the cost of computing

Analytical models to estimate Initial Rate (IR)and Expected Ultimate Recovery (EUR)


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Explicit Hydraulic Fracture Modeling

Single porosity model

both matrix and fracture cells are in the same

continuum

hydraulic fractures exist in the model representing

actual physical characteristics such as length,

height and width

no scaling of properties required


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Application to Eagle Ford

Condensate Window

Baseline model with expected characteristics

Sensitivity of selected parameters

Impact on Initial Rate (IR) and Expected

t mate ecovery


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Baseline model characteristics

Blackoil with no re-vaporization of condensate

Single porosity system with explicit fractures

Fracture widths = 0.001 ft or ~3 mm

Fracture porosity = 0.40 Fracture permeability = 10 D

Matrix porosity = 3.5 %

Matrix permeability = 100 nD


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Completions - Hydraulic fractures


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IR Clean-up Early productionIR impacted by fracture permeability

fracture complexity


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Expected ultimate recovery EUR


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Impact of yield on EUR~200 stb/mmscf

100 stb/mmscf


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Impact of condensate drop-out

condensate dominated flow in fractures


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Estimated drainage region

after 40 years

Significant pressure

drop away from thestimulated volume is

limited to ~50-100 ft~50-100 ft

~700-800 ft

Recovery efficiencies:10-15% range


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Questions?

shale tech coference 2011

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