Keeping Shale Formation Stability by Optimizing Drilling Fluids, in Yangta Oil Field, Western China

In this paper, the effects of drilling fluids on shale strength have been tackled, and a case study has been presented to<br>study the instability mechanism and the stability methodology in the shale formation. A program has been undertaken to<br>develop a better understanding of the effects of the using polymer drilling fluid on the shale mechanical properties and how<br>to modify its performance.