Petroleum Geological Characteristic Of Huoshiling-Yingcheng Formation In Shuangliao Fault Depression,Songliao Basin

Shuangliao fault depression is located in the southwestern part of the eastern rift zone,which lies in the southeast uplift of Songliao basin.The main area of fault depression is about 1233km2,and the maximum thickness of its stratum is 3680 m.The strata in the fault depression period includes Huoshiling formation,Shahezi formation and Yingcheng formation,however,little research has been done on these formations.To solve this problem,we identify the seismic facies by seismic data interpretation on the base of data collection,analysis on drilling and core,then analysis faulted structure and its evolution characteristics through the relationship between seismic facies and lithofacies in the study area established by the comparison of seismic and seismic data.Meanwhile,combined with comprehensive research on logging,core,seismic and testing data,we establish lithofacies form in Shuangliao fault,and clear off the characteristics of source rocks,reservoir and cap,then analyze the characteristics of oil and gas geology and the main controlling factors of hydrocarbon accumulation,and carries out the prediction of favorable exploration zones.Based on the analysis of single well facies andand the interpretation of seismic data,it is known that a number of terrigenous clastic rocks and volcanic rocks are speared in the Huoshiling-Yingcheng Formation of study area.We identify 5 lithofacies including lacustrine,fan delta and sublacustrine fan,subaqueous fan and volcano sedimentary facies,what`s more,7 central and 12 microfacies are identified at the same time.According to 16 types of seismic facies identified by "amplitude + continuity + reflection structure + shape" in the study area,combined with seismic correlation,the relation between facies and seismic facies,It is found that during the period of the Huoshiling formation,the source of the study area is mainly from the western and northwestern part of the fault depression,and is characterized by the shallow lake-fan delta –near shore subaqueous fan-volcanic facies system.And during the period of Shahezi formation,the provenance of the study area mainly comes from the West and Southeast,which is mainly composed of a semi deep lake-fan delta-near shore-subaqueous fan-sub lacustrine fan system.Whileduring the period of Yingcheng Formation,the provenance of the study area mainly comes from the west,northwest and Southeast,and is characterized by the shallow lake-fan delta-near shore subaqueous fan-sub lacustrine fan-volcanic facies system.According to the core test analysis of Shuangliao fault depression,the type of organic matter in Shahezi formation of source rocks is good,and stay in the evolution of mature stage,so we think its the main source rocks in the study area,while Yingcheng formation is the second and Huoshiling formation is the last because of the limitation of the number and quality of samples.The reservoir in study area is divided into two categories,clastic reservoir mainly distributed in the layer of Yingcheng formation and Shahezi formation,with characteristics of low porosity and low permeability;while volcano rock reservoir mainly develop in Houshiling formation,with characteristics of III-IV type porosity and V type permeability.According to the comprehensive analysis,it is known that the study area mainly developed "self-generation to self-accumulation" and "lower generation to upper accumulation” two types of source reservoir cap rock assemblage.Through the study of drilling oil test results,logging and seismic data we can get that the study area is mainly volcanic dome structure lithologic gas reservoir,which is developed in the volcanic dome structure of the Huoshiling formation.Its main controlling factors of hydrocarbon accumulation include favorable oil and gas source supply,favorable reservoir facies belt development,favorable source reservoir cap assemblage and favorable factors of reservoir formation.Accordingly,it is predicted that the development of the volcanic dome structure in the secondary bulge of Shuangliao depression is the favorable target area for oil and gas exploration in the future,which is favorable for the formation of the hydrocarbon source rocks of Shahezi formation and Yingcheng formation.