Strike-slip Fault Architecture and its Control on Fractured Carbonate Reservoirs: Insight from Outcrops in the North-western Tarim Basin, NW China

Abstract

Recent exploration has highlighted the critical role of strike-slip faults in shaping ultra-deep carbonate reservoirs in the Tarim Basin. This study integrates satellite imagery, UAV photogrammetry, outcrop surveys and microscopic analysis to investigate the architecture of these faults and their impact on reservoir petrophysical properties. The strike-slip faults exhibit cores consisting of calcite bands, fault breccias and fractures, while the damage zones are predominantly fractured. Thicker fault cores and fault zones are associated with more extensive reservoir development. Individual strike-slip fault zones are primarily characterized by two sets of fractures intersecting the fault at small angles. When two fault systems interact, the dominant pattern is two sets of fractures intersecting the main fault at small angles and one set at larger angles, facilitating the formation of large-scale reservoirs. We propose a model for the fault core, which primarily consists of a calcite band and fault breccias. These breccias are composed of original host rock, calcite cement and quartz, which exhibit poor physical properties, while fractures and vugs show favorable reservoir characteristics. This model offers valuable insights into the development of fault-controlled reservoirs, particularly in the Tarim Basin.