Property measurement and correlation for homogeneous and naturally fractured low permeability cores

Abstract

This thesis presents the results of measurements from ten naturally fractured Devonian Shale cores using a new laboratory technique to determine the distinctive properties of the matrix and the fractures. The new technique is based on a pressure pulse method. The principles of pressure pulse test are reviewed and the new laboratory equipment is described in this thesis. The new laboratory technique can be used to determine (1) the porosity of the matrix, (2) the permeability of the matrix, (3) the effective width of the fractures, and (4) the permeability of the fractures, in a naturally fractured, low permeability core sample. Matrix permeability as low as 10-9 millidarcies can be measured with the new technique. This is a significant step forward in permeability measurement because the lowest permeability that the pervious laboratory techniques could measure is in the order of 10-6 millidarcies. This thesis also presents the results of measurements with seven Barremian Chalk cores and nine Travis Peak cores to determine (1) the porosity and the permeability as functions of net confining pressure, and (2) the relative permeability as a function of water saturation. The techniques developed in our laboratory allows us to determine gas relative permeability and water saturation simultaneously from a single pressure pulse method. Water saturation is varied without removing the core sample from the equipment. The principles of the laboratory technique are reviewed in this thesis. Since the direct measurement of relative permeability is expensive or is impossible in many cases, we have developed a new mathematical model to correlate relative permeability data. We have also developed a new approach to normalize the relative permeability curves to obtain a single relative permeability curve for a specific formation. We have correlated the gas phase relativepermeability data for thirty two core samples from five wells using the new model. The results of correlation can be used to predict the gas phase relative permeability behavior in the corresponding formations.