Research On Seismic Interpretation And Structural Characteristics In Xuwen Exploratory Area Of Beibuwan Basin

Xuwen exploration area,located at Beibuwan Basin,has complex geological structure and poor seismic data,thus it's difficult for trap identification and target appraisal.Aiming at above two difficulties,structural interpretation method,and the main factors of hydrocarbon accumulation are studied to systematically evlaluates the advantageous drilling targets.Following recognitions are achieved.?1?According to the sea-land gravity,magnetic,electric and backbone seismic profiles,basin structure and sea-land transition relation are analyzed to define the sag structure,tectonic units regionalization and stratum filling characters.?2?Through the analysis on fault activity above the third-grade,the structure pattern of each key geological history period are confirmed.Combined with analysis on the structure recovery result and structural evolvement process,the structural evolvement is divided into 4stages-initial rift,intense rift,late rift and depression.?3?According to the fault depth,length and controlling effect on the sedimentation,faults are systematically analyzed.Through the study on fault combination in plane and vertical,tectonic style research is carried out to figure out its development characters and distribution rule.?4?Interpretation on Weizhou Group and Liushagang Group is carried out to recognize four-grade faults,verify the third-grade traps such as Maixi,Maidong and Maichendong,and finally find several favorable drilling targets.?5?Based on group division,through analysis on source,core facies,single-well facies,profile facies,and plane facies,analyze the sedimentary system of Liushagang group and Weizhou group in Maichen Sag,and Weizhou group of Wushi as wells as Jijia sag.With the application of seismic stratigraphy,sedimentary microfacies of E₃w₃ in Maichen sag are portrayed to figure out the favorable reservoir and gap area.?6?Aiming at the difference of oil accumulation key facors between Weizhou group and Liushagang group in Maichen sag,based on the geophysical analysis,reservoir prediction and shale gap evaluation,the“sweetness”of E₂l₃ and favorable reservoir-seal assemblage area of Weizhou group are figured out..?7?Evaluate the interpretation results,optimize the favorable exploration region and targets,and submit three wells:Xuwen X6,X7 and X8,in which X6 got the industrial oil flow in E₃w₃ and E₂l₃.