Characteristics Of Unconformity And Its Control To Hydrocarbon Reserves At The Late Stage Of The Dongying Formation In The South Slope Of Qinan Sag

Unconformity is a geological phenomenon formed after the formation is denuded and re-deposited.,it has a close relationship with oil and gas migration and accumulation,and has an important influence on hydrocarbon accumulation.Studying the characteristics of unconformity development and analyzing its control of oil and gas migration and accumulation have important guiding roles for further exploration work.Using rich logging,logging,and seismic data to study the unconformity of Qinan Slope in Qikou Sag in this paper,The unconformities in the study area are divided into four categories: onlap-truncation type,parallel-truncation type,parallel-parallel type and onlaptruncation type.Analyzed various types of unconformity development characteristics,distribution scope and distribution and discussed the influence of different types of unconformity on the law of hydrocarbon enrichment.Studied the types of unconformity surface and bottom lithology combination configuration and established classification criteria,and divide it into six contact types: S/M,S/S,M/S,S/S,S/V,and S/C.Drawn distribution maps of unconformity surfaces and bottom lithology configurations,the results show that its distribution is regional and zonal,and there is a close relationship between over-conversion belts of different configuration types and hydrocarbon-rich reservoirs.The lithology of the top of the underlying volcanic strata on the unconformity surface of the Guantao Formation and the unconformity surface were statistically analyzed,and the dominant sand bodies near the unconformity surface were divided,the results show that the unconformity of oil and gas accumulation is controlled by various factors.Unconformity not only provides good access to oil and gas migration,but also provides reservoir space for hydrocarbon accumulation.Unconformity plays an important role in oil and gas accumulation,such as migration,self-accumulation,capping and reconstruction,Studying the characteristics of unconformity development is of great significance to the search for hydrocarbon reservoirs.