Novel apparatuses have been developed to measure permeability using steady-and unsteady-state methods on nano-Darcy (nD) shale (source rock) using intact cylindrical samples returned to isostatic effective reservoir stress. The steady-state method uses a high pressure dual pump system using supercritical fluids. High pressure supercritical fluids have low viscosity and low compressibility. The effect of low viscosity fluid results in measureable flow rates and the effect of low compressibility fluid minimize unsteady-state transients thereby reducing the amount of time required to achieve steady-state equilibrium. Specially designed and configured pump systems, seals and sleeves reduce leak rates to allow Darcy flow and permeability determination below 1 nD. The unsteady-state method is based upon standard designs but is optimized for small pore volume. In this report we present a summary of over 200 such permeability measurements. Permeability is observed to be dependent on geologic parameters, such as, texture and composition. Stress dependence, with hysteresis, is observed for samples with and without fractures as is rate dependent skin (Forchheimer). An interpretation model where matrix storage feeds a progressively larger fracture network provides a logical basis for a dual-porosity reservoir simulation model. This dual-porosity model is used to understand the influence of reservoir production parameters, such as choke management.An additional observed effect is possibly related to pore collapse and disconnection. Pores associated with organic matter are softer than the surrounding mineral matrix. If these pores have a sufficiently small throat diameter, it is not hard to envision that they easily compact and close under increased effective stress as the result of reservoir depletion. Therefore, organic pore systems can become isolated unlike those of a sponge where fluids remain in pressure communication at all times. The implication of such pore isolation phenomena is that fluid material balance is not preserved during production and can contribute to large production decline rates. Development of an Unsteady-State Apparatus and Methodology for Low Permeability and Porosity Shales. SummaryA device and methodology has been developed for subject purpose under axial, radial and restricted three dimensional flow geometries. The intended use for this is as input to petroleum engineering models to evaluate producing potential of gas shales and other similar geologic formations. The application of this method to radial and three dimensional is new and without, to the authors knowledge, known published literature.Motivation for this work was to develop a method which would preserve geologic rock texture at reservoir stress utilizing cylindrical plug samples as opposed to standard commercial methods which uses crushed samples without stress.An outline of the mathematical model is presented in the second appendix and examples of the history match result at high, medium, and low permeability are shown in the below ex...

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