Abstract:

Differential spatial structures of the fault-controlled karst reservoirs constrain the efficient development of these reservoirs. The pore structure has been substantially studied for high-order strike-slip fault-controlled reservoirs, but rarely for low-order strike-slip fault-controlled reservoirs. Taking the Fuman oilfield in the northern depression of the Tarim basin as an example, different orders of strike-slip fault-controlled reservoirs were analyzed from the aspects of stress, depositional environment, and lithology, to compare their genesis and differences of pore structure, and the origins and exploration potentials of low-order strike-slip faults were examined. It is found that high-order strike-slip faults underwest strong faulting, resulting in an inverted triangular fracture pattern in the reservoir, with a decreasing scale from top to bottom. In contrast, low-order strike-slip faults experienced relatively weaker tectonic stress, leading to a normal triangular fracture pattern in the reservoir, with an increasing scale from top to bottom. The fracturing scale induced by low-order strike-slip faults is limited; however, a densely developed fracture network can lead to extensive reservoir fracturing. The primary factors influencing reservoir development are the depositional environment and lithology. The deep-seated low-order strike-slip faults in the Fuman oilfield can be divided into three zones from west to east, showing significant exploration potential.

Key words: Fuman oilfield, strike-slip fault, high-order, low-order, reservoir, reservoir space, exploration potential