Features Of Abnormal Pressure And Its Controlling On Hydrocarbon Accumulation In The Northern Liaodong Bay

Abnormal pressure spreads widely in the northern Liaodong Bay depression;normal pressure exists above 2200 m,while abnormal pressure appears more than 2200 m with a pressure jump.The pressure varies differently in different depth.The Overpressure formations are from Dongying formation to Pre-tertiary formation.The underpressure is the main reason of the abnormal pressure and the hydrocarbon-generation can also lead to it.It has 3 pressure systems in the vertical direction.The normal pressure system is Neogene pressure system while the abnormal pressure system is Dongying pressure system and Shahejie pressure system.The middle pressure system is given priority to Dongying formation.The overpressure center is in north liaozhong sag extending to the JZ9-3 and JZ25-1structure in Liaoxi salient.The lower pressure system is given priority to Shahejie formation.The overpressure center of northern and middle of Liaozhong sag on the plane is huger than Dongying pressure system.It develops huge thick-quality hydrocarbon source rocks.The existence of the middle pressure system strengthened the preservation of overpressure,overpressure system promoted the transmission of the lateral pressure.Overpressure reservoirs are more development in the study area,oil and gas along the direction of the residual pressure decreases,gathered by sag center to lateral migration accumulation.Overpressure of Paleogene pressure system provides the underlying layer sealing process and plenty of hydrocarbon accumulation dynamics,so as to make the Paleogene overpressure belt are favorable for oil gathering place around,as an important driving force of abnormal pressure of oil and gas accumulation in the study area affects and controls the space of the oil migration and accumulation,has close relationship with oil and gas enrichment of zoning partition.The same interval are great differences in different tectonic units of overpressure development situation,the residual pressure decreasing area is remaining antigenic favorable region of lateral migration of oil and gas accumulation,but the faults of vertical conducting have interference on the trend.