| The deposition of fan-delta in a small continental lacustrine rift basin is characterized by fast facies transformation and complex sand bodies contact relationship.The connectivity patterns and development characteristics of sand bodies of different genetic types show great differences,especially after entering the stage of high water cut development,the remaining oil is increasingly dispersed and the development difficulty is increasing.The contact style and connectivity of sand bodies directly control the water flooded characteristics of reservoirs.Fine reservoir architecture characterization and sand bodies connectivity characterization are of great significance to determine the optimal well layout scheme,realize efficient tapping of remaining oil potential and improving reservoir development level.Taking the formation of Subsection 1 of the Third Member of Shahejie of Gao-76 fault block in Nanpu sag as the research object,the conclusions are as follow.(1)Based on the investigation,measurement and investigation of a large number of outcrop and modern sedimentation in the early stage,the characteristics,geometric form and scale of fan-delta single sand body are defined,and the three-dimensional architecture model of fan-delta reservoir is established,which provides model guidance for the research of single sand body architecture in the study area.(2)Integrated application of well logging,seismic and development dynamic data,guided by the theory of sequence stratigraphy,the research ideas are seismic and logging combined,marked bed control,cycle contrast,multi-dimensional hierarchical constraint,dynamic verification,multidimensional closed.for the purpose of the study area layer of fine stratigraphic division and correlation and review,the establishment of a layer level isochronous stratigraphic framework.Fine stratigraphic division,correlation and review of the marked bed in the study area have been carried out,and a fine isochronous stratigraphic framework of single layer level has been established.(3)The original post-stack seismic data were processed and interpreted by frequency division,attribute fusion and genetic inversion,and the reservoir prediction method combined with well seismic was explored and optimized.Accuracy of sand bodies identification by well seismic combined were improved,and the distribution prediction of single layer level sand bodies were realized.The sand bodies in the main area of the study area are "wide strip",while the non-main area and Gao-9 block are "interlaced strip" or "narrow strip".(4)The spatial distribution and evolution of sedimentary microfacies were determined,and the distribution pattern and quantitative scale of single sand body were characterized.Interlacing strip distributary channel complex is developed near the study area,and the combination of narrow strip distributary channel and tongue mouth bar is developed far away.The statistical results of quantitative scale of single sand body show that the thickness of single underwater distributary channel sand body ranges from 1.4m to 6.3m.The width ranges from 57.65 m to 462.63 m,and the average width-thickness ratio is 41:1.The average width-thickness ratio of single mouth bar sand body is 73:1.The average width-thickness ratio of single overbank sand body is 25:1.(5)Based on the characterization results of interwell connectivity,the fandelta sand body connectivity pattern was established,and the criterion of interwell connectivity was established based on the interwell connectivity coefficient determined by dynamic inversion model.Inside,type I connectivity is the best,and the average connectivity coefficient is greater than 0.7 when drilling the same single sand body;type II connectivity is the connectivity between wells when drilling sand body with shear stacking relationship,and the connectivity varies widely,with the connectivity coefficient between 0.35 and 0.71;type III connectivity is the connectivity between wells when drilling the isolated sand body,which is not connected. |
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