Research On Difference Of Hydrocarbon Accumulation And Key Control Factors In Liaodong Bay Depression

Liaodong bay depression is located in the northeast of Bohaiwan basin,it is the offshore extension of onshore Liaohe depression in Xialiaohe depression,which proved to be a hydrocarbon-rich depression in the Bohai Bay basin.This paper analysed the main controlling factors,and then established the pool-forming model.The three sets of hydrocarbon source rock in Liaodong bay depression,Es3 source rock has the high abundance of organic matter,good types and high thermal evolution degree,followed by Es1 source rock,most Ed3 source rock with low thermal evolution degree and not in the main hydrocarbon generation period,In general northern is better than the southern,Liaozhong sag is superior to Liaoxi sag.With the difference of zone tectonic setting,sedimentary facies,diagenesis,reservoir space types,different zone reservoir conditions,cap rock,reservoir and caprock are obviously different.The cap of the low bulge area is superior,the main reservoir-seal association is source rocks in the upper part and reservoirs in the lower part,the cap of drape structural belt is high,the main reservoir-seal association is source rocks in the lower part and reservoirs in the upper part;due to the communication of fault,the capping of caprock is low,the main reservoir-seal association is source rocks in the upper part and reservoirs in the lower part;the buried hill zone developed low block buried hill trap.The drape structural belt developed drape anticline,hemianticline,fault-block trap;depression zone developed lithologic trap.Different types of structural belt has different conducting system.Near the large fault belt developed the fault type of conducting system;buried hill zone developed unconformity as the main channel of integrated transportation systems;the drape structural belt developed fault-sand body composite type of conducting system;the sub-sag belt developed lateral conducting sand body as the main characteristics of oil and gas transportation systems.The hydrocarbon accumulation process of three typical oil and gas field: JZ20-2N,JX1-1 and JZ25-1 have been analyzed.And on the base of analyzing the oil-gas distribution,establishing four major factors:(1)the control of the oil-gas difference distribution by the source rocks(2)the control of accumulation of the oil-gas by fault.(3)the control of oil and gas accumulation reservoir.(4)the control of the oil and gas accumulation by abnormal high pressure.The typical zone reservoir-forming pattern:(1)the pattern of the depression uplift zone.(2)the pattern of low-uplift buried-hill zone.(3)the pattern of low-uplift drape structure zone.(4)the pattern of sag zone.