High Resolution Sequence Stratigraphy And Sedimentary Microfacies Of Putaohua Reservoir In PU362 Block Of Daqing Placanticline

After years of continuous rolling development,the large-scale structural reservoirs have been developed,and the old oilfields have entered the ultra-high water cut period.It is particularly important to seek small-scale oil and gas enrichment areas from the main structural area to the structural edge.PU362 block Putaohua Reservoir an important reservoir increasing potential area in the south of Daqing placanticline.The sedimentary environment is the delta front subfacies at the end of the sedimentary system.There are some problems in its oil producing layer,such as thin,narrow and poor sand body.It is urgent to carry out a detailed study of sedimentary microfacies.Guided by the theory of high-resolution sequence stratigraphy,this paper systematically divides the internal high-resolution sequence stratigraphy of Putaohua oil layer in PU362 block.Within the high-resolution sequence stratigraphy framework,the seismic waveform indication inversion method,seismic attribute reservoir prediction technology,combined with the traditional logging facies model and outcrop data at home and abroad are optimized,It realizes the fine characterization of skeleton sand body to non skeleton sand body in the high-resolution sequence stratigraphic framework of Putaohua oil layer in PU362 block,determines the vertical evolution law of each short-term base level cycle in Putaohua oil layer in PU362 block,and finally establishes a sedimentary evolution model that can objectively reflect the characteristics of sedimentary system in PU362 block.The final study shows that:（1）Three sets of different levels of Lake flooding surfaces are selected as isochronous stratigraphic boundaries.Putaohua oil layer in PU362 block is divided into one long-term base level cycle,two medium-term base level cycles and 10 short-term base level cycles（PI1～PI7）,and then a high-resolution sequence stratigraphic framework of paraprovenance synsedimentary thinning of Putaohua oil layer in PU362 block is established.（2）Putaohua oil layer is a delta front subfacies sedimentary system formed under the control of northern provenance.Affected by the provenance in the north,West and North,there are seven sedimentary microfacies:underwater distributary channel,main body of estuarine bar,outer edge of estuarine bar,main sheet sand,non main sheet sand,underwater distributary bend and pre delta mud.（3）The seismic attribute most related to reservoir development is selected as the instantaneous amplitude attribute.The coincidence rate of using the amplitude attribute of drilling inspection to the well is 72.7%,and the coincidence rate of predicting sand body thickness by optimal seismic waveform indication inversion is82.1%.（4）The sedimentary system is affected by"Lake wave control",structural uplift at the end of the system,difference in material supply and high-frequency oscillation of lake level.Putaohua oil layer develops a sedimentary evolution sequence of rapid water retreat in the early stage,concussion in the middle stage and slow water advance in the late stage vertically.Small layer PI5₂（SSC3）is the maximum water retreat period.The research takes the purpose of fine exploration and development as the core,solves the problem of small-scale sand body identification in undeveloped areas,and realizes the fine characterization of sedimentary microfacies to the greatest extent.It provides reliable geological support for the adjustment of follow-up development plan and the formulation of deployment plan,which is of great significance to tap the potential of reservoir.