Studies On Formation Conditions And Main Controlling Factors Of Buried Hill Reservoirs In Bohai Bay Basin

Based on the massive data of geology, geochemistry and geophysics,Guided by thetheory of modern hydrocarbon accumulation and distribution,the hydrocarbon distributioncharacteristics and reservoir forming conditions of buried hill in Bohai Bay Basin weresummarized systematically;the hydrocarbon enrichment pattern was divided; the maincontrolling factors of enrichment difference were analysised deeply and the accumulationmodels were also established.Combined with previous research results, formation conditions of buried hillhydrocarbon of different depressions have been summarized systematically,the results showsthat source rock series of the depressions of early break early decline in the edge of thebasin are deeper than the others，so the source condition of these depressions are better thanthe others; uplift-erosion time of the depressions of the edge of the basin are looger than theothers，so the reservoir condition of these depressions are better than the others; Source-reservoir interlayer thickness of the depressions of the edge of the basin are smaller than theothers，so the conduct condition of these depressions are better than the others.The distribution characteristics of the buried hill reservoirs have been studied. On theplane,the reserves of buried hill reservoirs are mainly distributed in the peripheral of studyarea,but the reserves in the middle-inner annulus are relatively less; On the vertical, buried hillreservoirs are mainly enriched in the carbonate formation of middle-upper proterozoic andlower paleozoic.The hydrocarbon enrichment of study area is divided into three types:depression centre type, depression edge type and depressions-middle type.The buried hillreservoirs of depression centre type are mainly distributed in the edge of the basin, Theburied hill reservoirs of depression edge type are mainly distributed in the middle annulusof the basin,and the buried hill reservoirs of depressions-middle type are mainly distributedin the inner annulus of the basin. Through analogy analysis,the main controlling factors of enrichment difference of buriedhill reservoirs have been definited.Tectonic evolution background controls themacro-distribution of buried hill hydrocarbon, hydrocarbon-rich depression controls the planedistribution of the buried hill hydrocarbon,the maximum burial depth of the source rockcontrols the bottom boundary of the buried hill reservoirs, hydrocarbon supplying ability of thesource rock controls the reservoir-forming potential; reservoir properties control theenrichment degree of buried hill reservoirs,distribution of the high-quality reservoir controlsenrichment pattern of the hydrocarbon, fuel supply style controls enrichment aera of thehydrocarbon, Source， reservoir and conduction controls enrichment difference of thehydrocarbon.Based on the enrichment pattern and the difference of the main controlling factors, threeaccumulation models has been established in the aera: under source，deep depression，reservoir and conduction double-control tpye, external source，slop，source and conductiondouble-control tpye and middle source，salient，source and reservoir double-control tpye...