Structural diagenesis of deep carbonate rocks controlled by intra‐cratonic strike‐slip faulting: An example in the Shunbei area of the Tarim Basin, NW China

Abstract

AbstractThe Ordovician fracture‐cavity reservoirs in the Shunbei area of the Tarim Basin, China, afford an exceptional opportunity to use petrological and geochemical data to investigate structural diagenesis in deep low‐porosity (‘tight’) carbonate rocks. We obtained the relative timings for the development of fracture veins using petrological and cathodoluminescence analyses of minerals from representative samples. Textural observations combined with geochemical data determined the source and timing of the mineral‐forming fluid. The conceptual model of the overall temporal evolutions of structure and fluid flow developed herein indicates that fluid flow is a consequence of strike‐slip fault activity and the local stress state. Strike‐slip faults control the development of fractured–vuggy reservoir space and provide driving force for fluid flow along and across layers. Simultaneously, the direction of fluid migration can be influenced by local stress conditions, while compressive stress may restrict fluid flow. Results of this study suggest that open fractures develop as a result of structural diagenesis, rather than resulting from a single structural factor. The findings of this study can be used to inform the exploration and exploitation of deeply buried faulted carbonate reservoirs worldwide.