Study on of structural style of fault zone and reservoir characteristics in the northern slope of Tazhong Uplift, Tarim Basin, China

Fracture system plays an essential role in controlling the migration and accumulation of hydrocarbon. Previous study indicated that strike-slip fault is composed of several geometric segments. Each geometric segment is a set of independent reservoir units. Through the study of high-quality 3D seismic volume and drilling data on the north slope of Tazhong Uplift, as well as the analysis results of pressure build-up curves and logging data of typical wells, the structural style and hydrocarbon accumulation mechanism of the strike-slip fault on the north slope of Tazhong Uplift are described. The results show that the internal structure of S-1 fault on the north slope of Tazhong Uplift can be divided into five types of fracture cave structures, which are (1) linear main sliding surface; (2) isolated slit holes; (3) breakthrough fracture belt; (4) composite breakthrough fracture belt; (5) fracture zone with strong continuity along fault strike. The production data show that the drilling fluid production capacity of the breakthrough fracture belt and fracture zone with strong continuity along fault strike is the strongest, indicating that the breakthrough fracture belt is the main contribution unit of the reservoir. The above five structural units are consistent with the structure of the fault outcrop of the Hochwab Block in the Austrian Alps. The difference of structural type is caused by the differential fragmentation during the active period of strike-slip faults. The most serious fragmentation is in the pull-apart segment and uplift segment, which is easy to form breakthrough fracture belt. While relatively weak linear structures are developed in the translation segment, which also indicates that the pull-apart segment or uplift segment is the favorable position for reservoir development. This study provides a scientific basis for oil and gas exploration and development in the field of deep and ultra-deep carbonate rocks.