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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
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