Abstract:

In the Shunbei area of Tarim basin, Ordovician carbonate fault-karst reservoirs are controlled by strike-slip faults. These faults are distributed in rows and belts, and typically characterized by “laterally superimposed segments, vertically layered deformation and superimposed transformation”. On the plane, there are three types of fault systems: NE-SW, NW-SE, and NNE-SSW; and the faults of the Middle-Lower Ordovician can be divided into four styles: superimposed pull-out, superimposed indentation, linear translation, and composite graben. The different evolution of the Middle-Lower Cambrian source rocks in the east and west of the Shunbei area controls the present resource accumulation shown by “western oil and eastern gas”, and the plane segments of the fault zones control the internal structures of the reservoirs. The Ordovician fault-karst reservoirs have good source rock, reservoir and cap rock conditions. The faults communicate with the source rocks downwards, and the development of the fault-controlled fractured-vuggy reservoirs control the enrichment of oil and gas reservoirs. All these are mainly affected by the activity intensity, segmenting style, and the angle with the present principal stress direction in the fault zones.

Key words: Tarim basin, Shunbei area, Ordovician, carbonate rock, fault-karst reservoir, oil and gas reservoir, strike-slip fault zone, fault style, controlling factor of hydrocarbon accumulation