| Most of the old oilfields in China have entered the late stage of development of high-ultra-high water cut,the PI3 small layer in the research area is a large area of continuous complex thick composite sand body main oil layer,the current small layer division and sedimentary phase analysis can not meet the current oil layer agglomeration development needs,its reservoir internal complex characteristics cause it still has a large amount of residual oil retention,for this reason,it is necessary to finely characterize the sequence of PI3 composite sand body,sedimentation,sand body,for the remaining oil distribution and subsequent development to provide a solid geological foundation.Taking the PI3 reservoir in XQ area as the research object,under the guidance of high-resolution sequence stratigraphy,fine sedimentology and oil and gas field development geology,PI1-7 where the target layer in the study area is located is divided into 2medium-term datum rotations,6 short-term datum gyrations and 17 ultra-short-term datum gyrations,and 13 microphases and 22 energy phases of 1 phase,2 subphases are identified.Among them,the original PI3 small layer was subdivided into three ultra-short-term datum gyratory sequences(SSSC6～SSSC8),and a high-resolution sequence stratigraphic lattice of1564 wells reaching a single-stage river sequence was established,and 1 subphase and 7microphases and 12 energy phases were identified,namely the delta dividing plain subfacies,mainly including diversion channels,abandoned river channels,broken mouth river channels,broken mouth fans,natural embankments,overflow sand,and inter-diversion mud microfacies,and further subdivided the diversion channel into the main body of the diversion channel,the regular body of the diversion channel,and the edge of the diversion channel.Subdivide abandoned rivers into Type I abandoned rivers and Type II abandoned rivers;The overflow sand was subdivided into energy phases such as the main body of overflow sand,the constant body of overflow sand,and the edge of overflow sand,and the Logging phase mode of corresponding microphase and energy phase were established,and through the logging phase identification of 1564 wells,the sedimentary microfacies and energy phase planes of three ultra-short-term datum gyratory sequences(SSSC6～SSSC8)in PI3 small layer were finely described,and the composite sand body was split according to the splitting principle by the composite sand body splitting method,which laid a solid foundation for the accurate identification of single sand body.The vertical and transverse identification marks were used for the identification of single sand bodies in 1564 wells in the study area,and the vertical profile spread law of single sand bodies was analyzed,and the heterogeneity of single sand bodies was studied.On the basis of the fine dissection of the planar microphase and its internal energy phase,the flooding and residual oil characteristics of different types of energy phases and the same energy phase in different periods in the same period were analyzed,and it was concluded that the flooding degree of different energy phases in the same period from high to low was as follows: the main body of the diversion river,the regular body of the diversion river,the edge of the diversion channel,the abandoned river channel of type I,the abandoned river channel of type II,the breaking fan,the natural embankment,the main body of overflow sand,the constant body of overflow sand,and the edge of overflow sand.The same type of energy phase gradually increases the degree of flooding over time.The remaining oil types in the study area were identified: residual oil of waste river channel shelter type,residual oil of river channel edge type,residual oil of poor oil layer retention area,residual oil of fault shelter type,residual oil of river top type,sandwich shielded residual oil. |
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