New Measurements of the Petrophysical Properties of Top and Fault Seals

Abstract

Summary The paper presents new measurements on key petrophysical properties of fault rocks and shale top seals at subsurface conditions. In particular, results are presented from a new instrument that can make mercury injection capillary pressure measurements at reservoir conditions and accurately measure the threshold pressure. Absolute gas permeability from shale caprock samples measured using an extended pressure transient experiment are presented. New relative permeability measurements are also presented from fault rocks. The stressed MICP measurements suggest that the threshold pressures of fault rocks and top seals could be far higher than has previously been assumed. The transient gas permeability measurements indicate that fractures are often present within shales that may not be present in the subsurface indicating that traditional methods may result in an overestimation of shale permeability. The gas relative permeability behaviour of fault rocks appears to be partially related to their absolute permeability. The oil-water relative permeability behaviour of fault rocks seems highly variable and requires further investigation.