Study On Sedimentary Microfacies And Sand Body Distribution Of The Second Member Of Shahejie Formation In Tuo 7 Fault Block

After a long period of development,the first sand layer group of the second member of Shahejie Formation in Tuo 7 Fault Block in Shengtuo area has entered the stage of ultra-high water-cut development,and the production has been getting more and more difficult.The original small-layer division system can no longer meet the needs of development,and the single sand body research is necessary.Therefore,under the guidance of sedimentology theory,this thesis uses cores,well logging,and production data to study the single sand body of the first sand layer group of the second member of Shahejie Formation in the study area.Based on the study of stratigraphic division and sedimentary microfacies,the distribution of single sand body was studied.By analyzing the lithology,sedimentary structure,grain size and electrical characteristics of the study area,the facies characters of each microfacies were determined,and single-well facies analysis was carried out.The data show that the first sand layer group of the second member of Shahejie Formation in the study area was deposited in braided river delta plain subenvironment.The microfacies includes braid bars,braid channels,overbank and inter-distributary deposits.Based on core data and logging data,the first sand layer group in the study area was divided into 3 small layers and further divided into 6 single sand layers by finely dividing and comparing the stratum of the cored interval.The first small layer was divided into 2 single sand layers,the second small layer was divided into 2 single sand layers,and the third small layer was divided into 2 single sand layers.On the basis of the division of sedimentary microfacies and strata,the single sand body was described and portrayed in detail,and the boundary of the single sand body was determined by the vertical staging mark and the lateral boundary mark.Then,according to the corresponding relationship between the core data and the logging data,the sand body superimposition law was analyzed,and the single sand body superimposition law in the study area was summarized from the vertical and lateral aspects.The vertical sand body stacking styles were divided into cut stacking,stacking,and isolation.The side-up docking relationship was divided into direct connection type,isolated type,docking type,and isolated type.The connectivity of sand body was evaluated from the perspectives of vertical,lateral and two superimposed styles of different sand body.By analyzing the influence of hydrodynamic conditions on the sand body stacking style,the results show that the stacked and directly connected sand body stacking styles have the best connectivity due to the absence of argillaceous sediments and other interlayers,while other types such as isolated sand body have the best connectivity.The sand body has the worst connectivity.The finding of connectivity between single sand bodies was verified by the production data between water injection wells and oil production wells.