Tests show how oil muds increase shale stability

This article describes the problems and processes involved in preserving shale cores at a rig site and testing the shale on the downhole simulation cell (DSC) with an oil mud. Data on the composition of the shale as determined by x-ray diffraction, thin section analysis and atomic absorption are presented. Results of three DSC tests are given showing how the shale in the region around the wellbore can be affected by oil mud. This article discusses the development of procedures and presents part of the baseline data for the comparison of the performance of water based systems