The effective stress coefficient determines the influence of confining and pore pressures on rock properties. We measured the permeability of the Lockatong mudstone sample as a function of pore and confining pressures. Using our established laboratory protocol for such measurements, we estimate the effective stress coefficient for permeability. We use an initial stress cycle to remove the effects of inelastic deformation and microfractures due to core damage. The permeability values lie between 1.8 μD (in the first stress cycle) and 100 nD. The effective stress coefficient for permeability is found to be greater than one (nk = 1.28) at the lowest differential stress. We observe a strong dependence of effective stress coefficient with differential pressure – effective stress coefficient decreased from 1.28 at 2.5 MPa to 0.65 at 60 MPa. The measured permeabilities obey a simple power law dependence on the calculated effective stress.
Presentation Date: Tuesday, October 16, 2018
Start Time: 8:30:00 AM
Location: 202A (Anaheim Convention Center)
Presentation Type: Oral