Abstract:

Sinopec Northwest Oilfield Company recently struck a billion ton-scale oil/gas discovery-the Shunbei oil and gas field-in the deep carbonates of Shuntuoguole low-uplift， Tarim Basin. A new trap type-fault-controlled fracture-vuggy trap-is found to be the major container for oil and gas in the field. Analyses show that the traps take the fracture-vuggy layers along strike-slip fault zone as reservoirs and the overlying mudstone and local tight carbonates as caprocks. The reservoirs are probably the result of a tectonic disruption of the Middle-Lower Ordovician carbonates under strike-slip faulting that induced the formation of a large number of fractures， vugs and caverns. Based on the style and fragmentation of strike-slip faults as well as the distribution of internal reservoirs in the field， this study classifies the traps into four sub-types： transpression type， translation type， transtension type and composite type. This new type of trap further enriches the theory of marine carbonate reservoirs for oil and gas and provides a scientific basis for future exploration and development in deep and ultra-deep carbonates.

Key words: fault-controlled fracture-vuggy type, hydrocarbon trap, carbonate, Ordovician, Shunbei oil/gas field, Tarim Basin