Geomechanical methods for pore pressure prediction in complex geological structures: a case study of a field in southwest of Iran

Abstract

This paper presents a comprehensive investigation into pore pressure prediction methodologies, specifically addressing challenges in the upper zones of a field in southwestern Iran characterized by intricate geological complexities. Our analysis centers on the application of the drilling exponent (D-exponent) methodology, utilizing drilling parameters for accurate pore pressure estimation. Three methodologies are scrutinized: a section-specific approach, a site-specific analysis establishing unique normal compaction trend lines, and a novel method refining the normal compaction trend line mathematically. The Zamora method stands out as superior, especially in geologically complex regions like the Gachsaran formation, where overburden pressure may not be the primary stress. Implementing the Zamora method yields a substantial reduction in mean absolute percentage error (MAPE), enhancing pore pressure prediction accuracy by up to 9%. Additionally, a newly proposed method enhances accuracy by 7%. These findings underscore the importance of customizing pore pressure prediction techniques to the distinct geological conditions of specific regions. The outcomes not only advance our understanding of pore pressure prediction but also offer practical guidance for similar geological settings.