Sedimentary Study On Aershan Formation And Tenggeer Formation Of Northern Trough In Bayindulan Sag

The major petroleum-bearing northern trough of Bayindulan sag in Erlian basin is characterized with complex sedimentation evolution,various types of sandstone in slope and undistinguished facies features of favorable reservoir,which significantly confined the further exploration and well deployment.Therefore,it is necessary to figure out the sand body distribution features through systematical sedimentary study.Based on the previous study,the sedimentary facies features and reservoir characteristics of Aershan formation and Tenggeer formation of northern trough in Bayindulan sag are systematically analyzed using theories of petroleum geology geophysics and sedimentation.Geological information and data are fully taken advantage of,including field survey information,coring data,seismic data,mud logging data,laboratory analysis report,electrical logging data,oil test report and production testing report.Through analyzing regional geological settings and structures,it is thought that in Aershan formation depositing stage,several approximate NS dominant faults controlling the sag boundaries developed due to acute tectonic activities,resulting in the forming of half-graben basin characterized with the SE fault and NW overlapping.In Tengyi formation depositing stage,less tectonics resulted in faulted depression basin when depositing area was enlarging,but the sand body scale is downsized.Sedimentary facies analysis show that three microfacies like turbidite of lake facies,distributary channels of fan delta front,channels of middle nearshore submerged fan are developed in the northern trough.The distribution features of various sedimentary facies shown in vertical or in cross-section and sand body distribution area are explicit through analyzing single well facies and facies correlation crossing wells,associated with information of sand boy thickness,seismic facies features,etc.The petrologic features of clastic rocks,storage types,petrophysical properties are confirmed for the target intervals of study area.The influence factors of reservoir were analyzed as well.On the foundations of the forming features of discovered reservoirs,the favorable reservoir zone in the study area have been screened and selected to guide the oil and gas exploration in the future.