Research On Reservoir Structure And Remaining Oil Distribution In Delta

After years of rapid exploitation,most of the oilfields in China have entered the late stage of exploitation.The block development is in the period of ultra-high water cut,the recovery factor is reduced,the relationship between the underground oil and water is complex,and the heterogeneity between the reservoirs is strong,which makes the relationship between the reservoirs complicated,especially the distribution characteristics of the remaining oil are complex.A large number of different forms of remaining oil are distributed in the "dead angle" of the reservoir.In order to further improve the waterflood development effect,improve the oil recovery rate,maintain the stable production and increase the production of the oil field,people pay more attention to the study of the block sedimentary microfacies in the early stage,and ignore the fine description of the internal configuration of the reservoir.Therefore,this paper studies the distribution of remaining oil from the perspective of reservoir internal configuration to guide the later stage of water flooding.In this paper,Shasanzhong and shasanxia of block ma10 and block ma11 in Machang oilfield are taken as the research objects,in which shasanxia is the main research object.On the basis of fully describing the internal configuration of the sand body,the formation of the remaining oil and the distribution law of the remaining oil affected by the internal configuration elements of the sand body are described in detail.The traditional cycle thickness correlation method and high-resolution sequence stratigraphic division method are used for stratigraphic correlation and division.Establish more obvious marker layer and auxiliary marker layer in the area.According to the marker bed,the middle part of Sha 3 is divided into four sand groups,and the lower part of Sha 3 is divided into three sand groups.Based on the analysis of regional sedimentary characteristics and sedimentary facies marks,it is considered that the study area ma10 and ma11 blocks are delta sedimentary systems,the subfacies are delta front,and there are many microfacies.Based on the single well facies template,the cross-section of connected wells is drawn in the direction of vertical and parallel provenance,and finally the sedimentary microfacies plan is drawn in combination with the block characteristics to summarize the sedimentary facies model of the study area.Based on the study of sedimentary microfacies,combined with the previous research results in reservoir configuration,a 7-level classification scheme suitable for the internal configuration of Ma 10 and Ma 11 blocks in the study area is proposed.In this study,the main structure is 3-5 grade,that is,the inner accretion body,the single genetic sand body and the composite sand body.It is found that the relationship ofsand bodies can be divided into vertical and lateral superposition,and 8 single superposition models are divided.Based on the analysis of single sand body,it is found that there are vertical and lateral interbeds in the sand body of underwater distributary channel,and calcareous,muddy and silty interbeds in the single river mouth dam,and the angle of interbeds is further determined.Based on the comprehensive analysis of the configuration,the configuration of injection production well group is analyzed,and the specific horizon of water injection development is defined.Finally,based on the analysis of the internal configuration elements of the sand body and the latest development data of the oil field,the formation,type,distribution rule of the remaining oil in ma10 and ma11 blocks and the influence of the configuration elements on the distribution rule of the remaining oil are described in detail,and the relationship between the 3-5 level configuration units and the distribution of the remaining oil is summarized to accurately guide the exploration of the remaining oil in the later stage.