Evaluation Methodology And Application Of Tight Argillaceous Siltstone Formation Borehole Stability

Borehole instability mainly occurs in mud shale intervals or high clay content of tight argillaceous siltstone formation, which is a bottleneck that restricts oil exploration and development. For decades of research of borehole instability from the last century to the present, experts at home and abroad set up a system of mechanical and chemical coupling research model. In this method, getting the permeability and the membrane efficiency of formation is the precondition of processing the borehole wall stability analysis of dense formation, therefore, carrying out the pressure transmission experiments is necessary.In this paper, the writer based on the systematic investigation, has been transformed the existing pressure transmission equipment, developed a high temperature and pressure shale mechanical-chemical coupling simulation instrument, and with the help of the manufacturer, successfully developed the control software for supporting this equipment. Having experienced the improvement of equipment and software debugging, the experiment equipment can meet the requirements of the experiment, and can run stably for a long time. By the experiment equipment,we have got the rule of pressure transmission of tight argillaceous siltstone formation, shale formation, tight sandstone formation, and have worked out the matching permeability and membrane efficiency, and then we have measured the hydration diffusion coefficient of argillaceous siltstone under different pressure difference, got the relationship between the moisture content and the water absorption time in different location on the wall.Finally, after pressure transmission experiments, based on the utilization of rock mechanics theory, systematically studied the law of borehole wall stability of tight argillaceous siltstone formation under the drilling fluid soak for a long time.