Abstract:
Pakistan is located in tectonically active region, where the tectonic stresses play an important role in the oil and gas field development. The Kohat-Potwar fold thrust belt is a part of the active foreland folds and thrust belt in the Northern Pakistan. In this area, wellbore instability is one of the major issues in drilling operations for operating companies. Number of Exploration & Production Companies are operating in this region i.e. OGDCL, ORIENT, POL and PPL etc. All these companies, involved in drilling of exploratory and development wells, faced number of problems during drilling. These problems can always be attributed to geomechanics related issues such as wellbore instability, rock deformation, structural changes with stress regime, etc. In this paper, case study of a well drilled in this tectonically active zone is presented with all the problems encountered during drilling. The problems are addressed with the help of geomechanics study and how these problems could be avoided with the application of geomechanics concepts. Through this study, the specific drilling hazards were identified and the knowledge was captured. Recommendations were made to conduct a comprehensive geomechanics study to construct a mechanical earth model (MEM) consisting of in-situ stresses and mechanical properties of rocks, design safe mud weight and mud chemical composition to reduce shale instability, optimize well trajectory and casing point selection. A fit for purpose data acquisition was also recommended for geomechanics study. Based on pre-drill geomechanics study in well planning phase and real-time monitoring of wellbore stability while drilling, the potential risks could be identified and preventive measures could be taken to mitigate the drilling hazards for next well in this field. As a result, the non-productive time will be reduced and the costs will be minimized.
Page(s):
243-252
DOI:
DOI not available
Published:
Journal: Proceedings SPE-PAPG Annual Technical Conference, Volume: 0, Issue: , Year: 2009