Improvements of Formation Evaluation and Reservoir Engineering in Tight Gas Sandsthrough Selected Core Analysis Procedures. Annual Report, October 1989-December 1990

摘要

Core analyses of samples obtained from the Travis Peak, Cotton Valley andFrontier Formation have been performed to investigate the effects of the microfracture system on permeability anisotropy in tight gas sands. Preliminary results of these analyses indicate that directional permeability measurements are influenced by both natural and coring-induced microfractures. The aspect of the research project will lead to an improved understanding of the variations in directional permeability in tight gas sandstones, which ultimately has an impact on the production performance. The authors investigated the two most common methods of saturation change during lab resistivity index testing. These are the porous plate method and the centrifuge method. Results show that the method used to reduce saturation does not have a large effect on the calculated N when all saturations are averaged together. Based on tests completed, they believe that N values measured with the centrifuge method are valid for log interpretation purposes on tight gas sands. They calculated horizontal stress using various sets of input variables. They also included a discussion of the assumptions which are made in the derivation of the horizontal stress equations from Newberry, et. al.