advances in unconventional shale gas resources_lecture1920_gas flow and permeabi

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1、Instructor: Dr. Farzam JavadpourTel. (512) 232-8068Fall 2010GEO391Advances in Unconventional Shale Gas Resources Lecture 19 & 2011/08/2010Gas flow and permeability in shale gas systemsMacro-scale(Reservoir)Meso-scale(micro-fractures network)Micro-scale(Nano-pores network)Nano-scale(gas desorptio

2、n from nano-pore walls)wellboreMolecular scale (mass transfer from kerogen/clay bulk to pore surface(a)(b)(c)(d)(e)Gas is stored in kerogen and claysas dissolved gas and in pores as compressed gasCompressed gas in pores flowsthrough the pores first Then gas desorbs from the pore wallsThen gas diffus

3、es from the kerogen/claysto the pore walls and from there to the pore networkShale gas reserves and deliverability at different ScalesTriple porosityGanister GasJavadpour et al., JCPT, 2007Gas Evolution Lost Gas Estimation Average canister gas compositionImportant parameters to measurePorosity Measu

4、rements (boyles law)Boyles law: Grain volume or grain densityor sample skeleton densityArchimedes Law: Bulk volume or bulk densityHg injection: Bulk volume or bulk densityPycnometer apparatusMatrix permeability and productionGas flow in nanoporesnmU=0U=0U=UmaxmLprq84Poiseuille flowrGas flow in nanop

5、oresdKnPTkB22Knudsen numberMean free pathCriteria for validity of Poiseuille flowNavier-Stokes EquationNo-slip (Kn0.001)Slip (0.001Kn0.1)Continuum flowSlip flowDarcy flowKnudsen DiffusionJavadpour et al., JCPT, V. 46, No. 10, 55-61, 2007Kinetic theoryMaxwell-Boltzmann law of distribution of molecula

6、r velocitiesDistribution of molecular velocitiesVelocity formulationsMolecules collisions and mean free pathMean free pathMean free pathGas componentsMole(%)Collision diameter (, nm)Molar mass (kg/kmol)CH487.40.416.0C2H60.120.5230.0CO212.480.4544.0average0.4119.5Shale gas sample400 K350 K300 KMean f