| Summary: | As a spatial geological body, a strike-slip fault zone has a physically and chemically controlled compart- mentalization effect, which can form a unique fracture-cavity system with associated pore spaces inside the fault zone. A fracture-cavity system related to ultra-deep carbonate "fault-dissolution body" developed in Shunbei area of the Tarim Basin, and its "fault-dissolution body" reservoir is closely related to fault activities. The Shunbei strike-slip fault zone was studied with previous analyses and practices. The inner structure of the strike -slip fault zone was discussed, and the origin and characteristics of "fault-dissolution body" were analyzed. The spatial distribution of the "fault-dissolution body" reservoir is constrained by the boundary of the strike-slip fault. The external contour of the reservoir is mainly controlled by the fault zone, and the width is narrow while the depth is large. The reservoir space is mainly composed of "cavity" type caverns and a seam network formed by multi-stage structural rupture, and has undergone erosion and cementation via multiple types of fluids, forming dissolution holes and various pore spaces along the fracture system, and it leads to the complexity of the internal reservoir structure of fault- dissolution body. According to the dynamic changes of fluid participation and fluid properties in the fault zone, three genetic mechanisms can be identified: fault-capacity, karst and hydrothermal fluid erosion. The formation mechanism of the "fault-dissolution body" may be one of them, or a combination of two or three types. The most essential difference between "fault-dissolution body" and karst cave reservoir is that the composition of the former fracture-cavity system and the formation of reservoir scale are closely related to the fault activity, while the latter depends mainly on the water-rock interaction and the total matter volume removed.
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