Optimizing Fault Risking Strategies for Subsurface Resource Exploration on the Exmouth Plateau, NW Australia

Abstract

Abstract The understanding of geological fault growth history is critical in subsurface resource exploration, given the key role faults play in maintaining reservoir integrity. Traditional practices involve assessing fault initiation, propagation, segmentation, linkage, and reactivation to elucidate their growth mechanisms and history. Various traditional methods, complemented by fault growth models, are employed, with the choice of method contingent on the study's scope and objectives. In this study, we use high-quality, high-resolution three-dimensional (3D) seismic reflection data to investigate the evolution of two primary faults intersecting the Exmouth Plateau, offshore Northwest Australia. By applying displacement analysis techniques, including variations of fault displacement/throw with distance (T-x), throw (T) with depth (T-z), and Allan diagrams, we scrutinize potential leaking or compromised segments along the interpreted faults. Our results show that the faults are oriented in the NNE-SSW direction and developed under extensional regimes from the Middle Triassic to Late Jurassic. These faults show high segmentation along strike and mild segmentation along dip. Their T-x profiles reveal a multiple-segment profile of C-type and hybrid C-type, indicating evolution from the linkage of different fault segments at local displacement minima. Importantly, the Allan diagram highlights a leakage zone along F1 at the Top Rankin Beds unit, where a throw of less than 10 ms (approximately 10 m) was recorded. This area represents a potential site of subsurface fluid leakage, including oil, CO2, hydrogen, and other gases. The techniques and results presented here have profound implications for subsurface resource exploration in the studied area, with broader applications in similar settings worldwide.