Controlling Of The Oil-Source Faults For Oil And Gas Distribution In The No.2 Structure Belt,Nanpu Sag

Based on the combination of geology and geochemistry and quantitative and qualitative analysis,the origin of crude oil,controlling effects of faults on hydrocarbon migration and accumulation,geochemical characteristics and types of oils were identified.In addition,the types of oil-source fault were divided.Then,the activity and relationship between active period of fault and main hydrocarbon expulsion period were analyzed.Finally,the dissection of representative reservoirs and controlling fators were analyzed.The results indicate that oils belong to freshwater,continental,light,mature crude oil with no biodegradation in the No.2 structure belt,Nanpu Sag.Oils were divided into Type A and B,and mainly were Type B.Type A oil was mainly distributed in wellblocks NP2-3 and NP2-1,while Type A was chiefly distributed in wellblock LPN1.Type A oil was closely related with Type I source rock,and mainly derived from Es2+3 and ESi source rocks within the freshwater environment.Type B oil was from Type II source rock,and chiefly from Ed3 within the higher salinity condition.The faults were divided into three types,which are cutting Es2+3,Esi,Ed3 oil-source fault,with piecewise growth characteristics,and were mainly active in the late Nm.The middle-shallow oils were mainly accumulated in first member of Paleogene Dongying Formation,some were gathered in Neogene Guantao Formation.Middle-shallow oil types and distribution were dominated by source rock and fault.When SGR is greater than 0.53,the fault can effectively seal oil and gas,and is better for oil accumulation.The evidences of physical property of crude oil,biomarker,and formation water indicated that the fault is the important pathway for deep oil migrating.