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Shale Gas Matrix Permeabilityfrom Unsteady-Statetechniques Review andModeling

Thesis Project Maria F. Gonzalez

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Objectives

ReviewMethods

ReviewModels

ReviewFactors

ObtainImproved

Model

ObtainAnalyticaland/or

numericalsolutions

Validateand

Verification

Data Fromthe

IndustryPublish

Fall 2012 Winter 2012&Spring 2013

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1. Highlights onthe Review of

Methods

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Km Measurements

P=Pd-Pu

PdPu

CorePlugs

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Km MeasurementsLuffel et al. Original GRI method

CrushedSamples

A measured weight of crushed shale (15 to 30 gr)is placed in a sample cell. Helium is then allowedto expand into the sample cell from a referencechamber at 200 psig.

Pressure instantly drops to a level dictated bydead space in the sample cell.

Then, pressure decays with time to a lowerpressure (stabilization pressure) as helium movesinto the pores within each shale chip

Helium

At 200

psig

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Km and porosity effect on

Pressure Pulse. Haskett et al

Same porosityDifferent PermeabilityChanges time required to

achieve Stabilization Pressure

Same PermeabilityDifferent porosity

Changes stabilization pressure

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Particle Size and Duration of

Test. Profice et al.

Region of the curve beinguseful to analyze thepermeability strongly

depends on chips

size.

This study uses an unimodaldistribution of sphericalparticles.

Real case -> several sizes

and shapes (drill cuttings)

Sensitivity analysis neededwhen modeling realsamples

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Modeling

Approaches

DiffusivityEquation

Initial &BoundaryConditions

SolutionApproaches

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Haskett et al.s approach

cores Travis Peak Formation Dimensionless pseudopressures and adjusted

pseudo time

Diffusivity equation

Transformation Laplace

Solution in Laplace Space

Inversion

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Cui et al. 2009

Late Time Technique Cuiet al (GRI) Curve Fitting

Simplifications derived onconsidering as constantsome of the coefficients.

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Javadpour et al. 2012

Crushed Samples

Cui et al.s plusSlip flowKnudsen Diffusion

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Javadpour et al. 2012

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An idea: Analog Modeling -

option

Analysis of derivative data from pressure pulse data at late timeshas been done for CORES.

Different Flow Regimes identification within samples Applicable tocores How to apply to crushed samples?.

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What will affect the

experiment and model? Amount of crushed particles in the sample cell

Particle size

Equilibrium pressures (pressure at which thepressure decay stops)

Different gases.

Starting state of the crushed rocks

Starting state of the measurement apparatus

Desorption occurring under different testingconditions?

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Next Modeling

Pseudopressures

Pore Proximity Effects Z factor

Adsorbed Layer

Desorption effects on Pressure pulse tests?

Other flow regimes different to slip

Try different approaches of Modeling

Pressure pulse penetration

Pressure Pulse diffusion

Solution (with and without simplifications

sensitivity analysis)

Numerical

Analytical

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Every Shale is Different and

the methods should be

adaptative