Shale Permeability Determined by Simultaneous Analysis of Multiple Pressure-Pulse Measurements Obtained under Different Conditions

Abstract

Abstract Several pressure-pulse measurements are conducted on similar plugs extracted from various tight-shale formations under different boundary conditions. A theoretically rigorous model-assisted analysis of a number of data sets is carried out for achieving uniqueness in determination of intrinsic shale permeability. The best estimate values of the unknown parameters, including the Langmuir volume and pressure, and the intrinsic permeability of the shale samples at a reference condition are determined by matching the numerical solution of our improved non-Darcy model simultaneously to several sets of the observed pressure-pulse transmission data. Simultaneously, we delineate the dominant characteristics of the apparent permeability and the contribution of the various flow regimes. It is concluded that our improved method provides a better match to the pressure-pulse decay tests than the previous models which assumed Darcy flow. Further, our formulation allows for model-assisted extrapolation to other conditions once the unknown parameter values have been estimated under laboratory testing conditions.