The mixed deposition of terrestrial clastic rocks and lacustrine carbonates in the first and second members of the Shahejie Formation in the Bohai Bay Basin is one of the most essential oil-bearing strata in the Paleogene.To clarify the depositional characteristics and development model of this type of reservoir and to better serve the exploration and development,taking the Bozhong C structural area as an example,based on the date from drilling,logging,seismic,and core analysis,it was studied in detail on the petrological characteristics,influencing factors,and development model of the mixed deposition in the first member of the Shahejie Formation in the study area.The results show that the mixed sedimentation of the first member of the Shahejie Formation in the study area mainly develops two rock types:bioclastic dolomite and grainy glutenite,which belong to the fan-delta type and bioclastic beach type of mixed sedimentation.Among them,bioclastic dolomite belongs to the medium-high porosity and medium permeability reservoir,which is the main contribution layer of oilfield productivity.This reservoir type is mainly affected by ancient landscape and paleoclimate factors.Based on the fine restoration of paleogeomorphology by the back-stripping method,combined with the actual drilling results,the development model of"bioclastic dolomite island-like distribution,good sunny gentle slope and steep slope difference of back-shade"is proposed,and then it is predicted that the southern gentle slope area of the study area is the"sweet spot area"for the development of bioclastic dolomite.The research results have successfully guided the adjustment and potential tapping of the study area,and have reference significance for similar oilfield reservoir research.
mixed depositionancient landformdevelopmental patternBohai Bay Basin
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