Surface and subsurface deformation analysis of Sarajeh gas field and adjacent areas: Implications of tectonic deformation on gas reservoir characteristics

This study delves into the surface and subsurface deformation analysis of the Sarajeh Gas Field and its adjacent areas, with a particular focus on structural geology. Utilizing comprehensive geological surveys and advanced deformation analysis techniques, the research aims to identify and characterize the deformation patterns present in both surface and subsurface layers. The surface deformation analysis reveals significant deformation in the southern part of Sarajeh, especially within the Hossein Abad partition. Here, the Qom-Zefreh fault line undergoes a notable shift from a north–south to a northwest–southeast orientation, resulting in pronounced folding and deformation. In the subsurface analysis, the Lower Red Formation is identified as the most deformed layer. This is primarily due to its composition of evaporites and salt, combined with the presence of a detachment layer between the Eocene volcanic rocks and the solid Qom Formation. These geological characteristics contribute to the extensive deformation observed in the Lower Red Formation. The deformation of surface and subsurface rock masses is chiefly governed by the interplay between regional tectonics, fault geometry, lithological heterogeneity, and mechanical stratigraphy, with the Qom-Zefreh fault system and evaporite-rich detachment layers playing pivotal roles in strain localization and structural complexity. Stress-induced deformation in the Sarajeh anticline simultaneously enhanced reservoir quality through fracture development and compromised seal integrity via fault-related compartmentalization, critically shaping gas accumulation and flow dynamics. The study demonstrates how this deformation impacts reservoir reliability: fractures enhance permeability in the Qom Formation (supporting gas storage), while compartmentalization poses risks to seal integrity. The findings from this study provide critical insights into the structural dynamics of the region, offering valuable information for future geological studies, resource management, and potential exploration activities in the Sarajeh Gas Field and its surrounding areas.