Theory 22/Mach Number/Shale gas
Shale Flow Is a Mach Problem
The claim
Gas production from nanoporous shale is set by the local Mach number in the pore network, so the same pressure drawdown produces different flow regimes in different pore sizes.
01Mechanism
At small pore scales, gas velocity relative to the speed of sound determines whether flow is continuum, slip or transitional, and each has a different permeability.
02Prediction
Permeability should track pore Mach number.
03Refutation
Permeability tracking pore size alone would remove the velocity term.