Controlling Of Fault On Oil Accumulation In Taidong Area Of Songliao Basin

On the basis of analyzing the fault geometry characteristics and kinematic rule, we discuss the mechanism of dense fault zones of the top and bottom of Qingshankou formation in Sanzhao depression. It can be concluded that under the influence of east-west tension stress field, T11dense fault zone is inherited from the underlying T2one, which is controlled by the slant extension caused by the orientation of stress field and basement rift. The process of dense fault zone is controlled by basement faults, crater and other weak stress belt. Faults in Taidong are mainly oriented NNE, nearly SN and NNW with small scale, less than45m fault displacement, and less than9km extended length. There are6dense fault zones, in which faults are paralleled showing a v-shaped combination on profile. It indicates that the extension of east-west tension stress field is controlled by sag cause dense zone.Shallow water delta microfacies is mainly developed in Putaohua reservoir of Taidong slope area, channel sandbodys are NNW, which is oblique crossed by faults. The oil reservoir type is mainly fault-lithologic reservoir and structural-lithologic reservoir. The oilness is getting increasingly worse from top to bottom under the influence of lithology. It developed5fault-terrace belt divided by fault and the reservoirs is east-to-west migration trending on plane, oil-bearing in single fault terrace zone became gradually from east to west. The fault controls the reservoirs formation and distribution:NNE and nearly SN faults provided traps for oil and gas. The antithetic faults are more favorable for oil and gas to accumulate than synthetic. The fault lateral sealing ability controls the accumulation degree.Guided by fault controlling reservoir theory, we conclude the model of fault controlling oil migration and accumulation:oil generated at the center of Sanzhao depression migrates to Putaohua reservoir along the fault. Then it migrates laterally to Taidong slope along the NNW sandbody and accumulates when meeting antithetic NNE faults or nearly SN faults, which forms fault-lithologic, fault block or lithologic updip accumulation models. The filling extent is influenced by the fault sealing ability. As the oil column height increased, oil will cross fault and migrate to next planning step. As is stopped by the next planning step and insufficient oil supplying, each oil distribution gets worse in step-fault zone from east to west finally.