Title: Wellbore stability charts for shale and carbonate formations during drilling operations with field applications

Authors: Ahmed Abbas Al-Ajmi; Bilal Shaheed; Adel M. Al-Ajmi; Hamoud K. Al-Hadrami; Mohammed Hamed Al-Aamri

Addresses: Hydrocarbon Maturation Center, Petroleum Development Oman, Muscat, Oman ' Interpretation and Evaluation Services, Weatherford, Muscat, Oman ' Department of Petroleum and Chemical Engineering, Sultan Qaboos University, Muscat, Oman ' Department of Petroleum and Chemical Engineering, Sultan Qaboos University, Muscat, Oman ' Hydrocarbon Maturation Center, Petroleum Development Oman, Muscat, Oman

Abstract: Wellbore instability issues represented by well collapsing resulted in a tremendous loss of time and money in the oil industry, where 90% are related to shale. Despite carbonate rocks experiencing fewer instability issues than shale or sandstone, most global hydrocarbon reservoirs are carbonate. Utilising a three-dimensional stability model adopting the Mogi-Coulomb failure criterion, stability charts predicting the collapse pressures during drilling in shale and carbonate formations have been generated. The introduced stability charts have been generated to cover the most common scenarios in Oman and similar locations. Six field case studies are conducted utilising the generated stability charts for geomechanical analysis. The fields applied mud densities at the associated drilling trajectories were consistent with the predicted results from the generated stability charts. These results support adopting the presented stability charts as a simplified geomechanical approach in oil fields. [Received: October 5, 2022; Accepted: January 25, 2023]

Keywords: wellbore stability; shale; carbonate rock; failure criterion; mogi-coulomb criterion; stability model.

DOI: 10.1504/IJOGCT.2023.131641

International Journal of Oil, Gas and Coal Technology, 2023 Vol.33 No.3, pp.205 - 232

Received: 05 Oct 2022
Accepted: 09 Feb 2023
Published online: 21 Jun 2023 *

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