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

• Published in: Basin research Vol. 34; no. 5; pp. 1601 - 1631
• Main Authors: Yu, Jinxin, Shi, Kaibo, Wang, Qiqi, Liu, Bo, Han, Jun, Song, Yanchen, Kong, Yue, Jiang, Weimin
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01.10.2022
• Subjects: Carbonate rocks; Carbonates; Cathodoluminescence; Compressive properties; Diagenesis; Exploitation; Fluid dynamics; Fluid flow; Fractures; Geochemistry; Geological faults; Minerals; Ordovician; paleo‐fluid; petrology; Porosity; Reservoirs; Shunbei; Slip; Stress; structural diagenesis; Tarim basin; China; Tarim Basin
• ISSN: 0950-091X; 1365-2117
• DOI: 10.1111/bre.12672

The 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. Petrologic and instrumental analyses were used to reconstruct the characteristics and timing of vein‐forming fluids in the Ordovician limestones in the Shunbei area, Tarim Basin. In light of the study area's complex structural history, we then deciphered the structural diagenesis controlled by intra‐cratonic strike‐slip faulting. The coupling of brittle deformation and diagenesis (ie., fracturing and cementation) also provides new insight into the creation and persistence of open fractures in tight carbonate rocks.