oa Improved Calibration of Borehole Stability Models in Shales Using Hollow Cylinder Laboratory Tests

To improve the understanding of behavior related to the borehole geometry in shales, and to generate better input data to borehole stability simulators to be used when estimating the stable mud weight window, we have developed an experimental methodology whereby we perform rock mechanical laboratory tests on various shales in a hollow cylinder geometry. We present our methodology, including both laboratory measurements, how such data and other data are fed into our borehole stability simulator, as well as results for specific cases. These tests allow for a better understanding of failure mechanisms causing borehole instabilities and providing calibration data to borehole stability models. When integrated into proper borehole stability simulators it thus represents an applicable tool for attaining improved drilling performance while drilling through shales.