Hydrocarbon migration system of Fulaerji oil field, Songliao Basin, NE China

Through sedimentologic and petroleum geologic analysis of over 300 exploration wells in the north part of the west slope in the Songliao Basin, the conduit role the incised valley played in the oil and gas accumulation of the Fulaerji oil field is investigated. The major pays in the Fulaerji oil and gas field are the second and third members of the Cretaceous Yaojia Formation, where the hydrocarbon comes primarily from the Qijia-Gulong sag about 80 km east. The pathway of long distance hydrocarbon migration is the overlapping sandstone complex which fills the incised valley. The incised valley deposits overlapped on the delta deposits toward basin, and connected with shore-shallow lake sandy beach-bar formed during the highest lake flooding period toward the basin margin, constituting a sand rich sedimentary complex of delta - incised valley filling - shore sandy beach bar. Towards the basin, delta sand branches and pinches out in mudstone (mature source rock), transporting the hydrocarbon generated in the effective hydrocarbon kitchen to the incised valley filling body, the incised valley filling deposits transported hydrocarbon for a long distance to the updip pinching sandy beach bar lithologic trap, giving birth to the Fulaerji oil and gas reservoir. In the sand-rich sedimentary system related to the incised valley filling, the effective hydrocarbon transporting system is limited along Well Du 412 - Du 71 - Du 65 - Jiang 39 - Jiang 41 and Fulaerji oil and gas field. The pure hydrocarbon transporting layer is a water production layer with a high degree of hydrocarbon impregnation and low residual oil saturation. Baiyinnuole, Erzhan, Alaxin, Jiangqiao oil and gas fields distributed like a string of beads in NW are closely related to this effective hydrocarbon transporting system.