Wellbore Stability in the Olmos Formation

Wellbore stability is crucial for optimizing production and maintaining safety for any given oil and gas extraction site. A stable wellbore will reduce potential rock failures and as a result, eliminate remedial costs for the company associated with wellbore collapse. An unstable wellbore can negatively affect production. The goal of this research was to design a stable wellbore in the Olmos Formation of South Texas. The design was done in a way that can be easily repeated for multiple formations. Parameters under consideration for design were earth stresses, pore pressure, drilling fluid design, and drilling parameters. Safe and environmentally-friendly drilling processes were determined. An ideal design consists of a drilling fluid density that will balance formation pressure without fracturing the rock. This drilling fluid was designed by calculating the earth stresses and using Mohr's Circle analysis to determine an acceptable fluid density range. Graphing software was used for the Mohr's Circle analysis. A stable wellbore was designed that is safe, environmentally-friendly, and economically feasible. Optimal drilling fluid density was determined for the drilling zone of interest. Upon completion of this research, various wells drilled in different formations can be easily designed for wellbore stability.