Structural patterns of fault damage zones in carbonate rocks and their influences on petroleum accumulation in Tazhong Paleo-uplift, Tarim Basin, NW China

Abstract Based on the outcrop survey, 3D seismic data interpretation, drilling data analysis, the structural patterns and distribution of fault damage zones in carbonate strata of Tazhong Paleo-uplift were established to reveal the oil and gas enrichment law in the fault damage zones. The following findings were reached: (1) Through the filed survey, the fault damage zone system consists of fault core, damage zone with branch fault and fracture network. Affected by the active nature of the major faults, the fault damage zones differ in planar pattern and scale along the major faults. (2) 3D seismic profiles reveal that there are three types of fault damage zones in carbonate strata in Tazhong paleo-uplift, strike-slip fault damage zones, thrust fault damage zones and superimposed fault damage zones. Featuring 3 flowers and 3 root belts in vertical, the strike-slip fault damage zone can be subdivided into linear type, oblique type, feather type and horsetail type in plane. Thrust fault damage zones can be further divided into fault anticline type, anticline type and slope type. As the superimposition result of the above two kinds of fault damage zones, superimposed fault damage zones appear in three patterns, intersect type, encompassment type and penetrating type. (3) Cores from wells and geochemical data show oil and gas may migrate along the major fault and laterally. The feather type in strike-slip fault system, fault anticline type in thrust fault damage zone and intersect type in superimposed fault damage zone are possible sites for high production and efficiency wells.