It remains highly challenging to decipher the coupling between multistage fracturing and diagenesis in subsurface strike-slip fault zones. Based on seismic fault analysis, core and thin-section observations, and compiled calcite-cement U–Pb ages and fluid-inclusion data, this study investigates fracture diagenesis and its implications for Ordovician carbonate reservoirs along strike-slip fault zones in the central Tarim Basin. Seismic interpretation shows that faults terminate upward at the tops of the Ordovician carbonate, Silurian–Devonian, and Permian strata, broadly constraining three stages of fault and fracture activity. The fault zones are characterized by multiple fracture sets, variable diagenetic compaction and pressure solution, and multistage cementation and dissolution. The main fracture-diagenetic processes include argillaceous filling, multistage dissolution, calcite cementation, and minor infiltration of hydrothermal minerals, including fluorite, dolomite, and pyrite. Fractured reservoirs are strongly heterogeneous and are mainly confined within fault damage zones. Fracture density, reservoir porosity, and oil and gas production generally decrease with increasing distance from the fault core, although the trends are highly scattered. Integrated geochronological and regional tectonic data indicate that multiple fracture-diagenetic events initiated in the Middle Ordovician and were largely completed before the Carboniferous. These events include Middle Ordovician fracturing, contemporaneous dissolution and karstification, and long-lasting burial and hydrothermal diagenesis during the Late Ordovician, Silurian, Devonian, Carboniferous, and Permian. The results suggest that penecontemporaneous to shallow-burial meteoric dissolution contributed substantially to reservoir porosity in the Ordovician carbonates, whereas early compaction and cementation destroyed most primary porosity. Later multistage fracture diagenesis further modified reservoir quality and enhanced reservoir heterogeneity. These results indicate that intensive fracturing, dissolution, and cementation during early faulting stages, rather than late burial dissolution or hydrothermal activity alone, primarily controlled the formation and distribution of fractured reservoirs. This study highlights fracture diagenesis as an effective approach for reconstructing and evaluating deep ancient fractured reservoirs along fault zones.

With the increasing exploration and development of deep (>4500 m) hydrocarbon resources, fault-controlled reservoirs have become important sweet-spot targets in deeply buried tight rocks. However, it remains challenging to decipher the coupled relationships among deformation, fluid flow, diagenesis, and reservoir evolution within fault damage zones. In this review, we synthesize recent advances, including contributions to this Special Issue, on deformation, diagenesis, and reservoir development within fault damage zones in sedimentary basins. Fault-zone architecture commonly comprises a narrow fault core and a wider damage zone, with fault cores supported by particles, matrix, or cement, and damage zones characterized by outward-decreasing deformation intensity and fracture network complexity. Although fracture intensity, porosity, and permeability commonly follow a power-law decrease with increasing distance from the fault core, these parameters are highly scattered because they are jointly controlled by complex structural and diagenetic overprinting. Non-Andersonian fault-tip propagation, fault interaction, linkage, and reactivation play key roles in the development of wide and heterogeneous fracture zones. During progressive burial, mechanical compaction and cementation generally reduce primary porosity, whereas dissolution may generate or enhance secondary pore systems. Hydrothermal dissolution can locally improve reservoir quality, whereas mineral precipitation commonly occludes pores and fractures and reduces permeability. Except for the high-energy microfacies, the coupling between fracturing and contemporaneous, burial-related, or supergene dissolution is critical for the formation and preservation of secondary reservoirs. Integrated faulting period analysis and U-Pb dating of carbonate cements within fractures provide an effective approach for reconstructing the timing of fracturing, fluid flow, and diagenetic modification. In sedimentary basins, heterogeneous fractured reservoirs are unevenly distributed along fault damage zones. Their formation is controlled by the complex coupling of lithology, structural deformation, fluid flow, and diagenesis. Therefore, the key scientific challenge is to quantitatively characterize the spatio-temporal evolution and coupling mechanisms of deformation, diagenesis and fluid flow control on reservoir properties within fault damage zones. Ultimately, this review provides a novel, time-resolved framework for predicting deep sweet-spot reservoirs, shifting the paradigm from purely structural description to quantitative structural–diagenetic modeling.