Study On Remaining Oil In The West Chang 6 Reservoir Of Qujiagou In Wayaobao Oilfield

In response to the problems of poor development effect,low recovery rate,multiple low production and low efficiency wells,unclear understanding of production decline and remaining oil,and unsatisfactory water injection effect in the western area of Qujiagou in Wayaobao Oilfield,this article divides the Chang 6 oil layer in the study area into small layers,deepens the understanding of reservoir geology,combines geological characteristics with production and development,and conducts research on remaining oil.Based on logging curves,core data,production data,and other data,this article comprehensively analyzes the structure and sedimentary microfacies of the main production layers in the study area through various methods,and clarifies the structural characteristics and sedimentary microfacies types within the area;Conduct fine characterization research on single sand bodies,clarify the types of single sand bodies,and analyze the stacking types of single sand bodies from multiple perspectives and their impact on the distribution of remaining oil;Conduct research on the development characteristics of the area using the production decline method,analyze the types of single well production decline in the research area,and calculate the remaining recoverable reserves of a single well;The research area belongs to multi-layer combined production,and the KH value splitting method is used to split the production of a single well,clarify the remaining reserves of each sub layer,analyze the distribution characteristics of remaining oil from multiple perspectives,and propose corresponding potential tapping strategies and suggestions.The results show that:1)The thickness of single sand bodies in the main layers of 6₁²,6₁³,and 6₂¹is mostly distributed between 1-4m,with small thickness.Vertically,there are three types of stacking:separation type,vertical connection type,and superimposed shear type.Horizontally,they are divided into three types:bay contact,docking contact,and lateral shear contact.In terms of spatial composition,they are divided into 9 combination types.2)The degree and location of residual oil enrichment vary among different stacked types.Among the spatial combination types of sand bodies in the study area,the vertical shear lateral shear type and stacked shear lateral shear type sand body spatial combination types have no enrichment of residual oil,while other spatial combination types have enrichment on the flanks of the upper sand body.In addition,the separated spatial combination type of residual oil is also enriched at the top of the lower sand body.3)The number of wells with linear decline,exponential decline,harmonic decline,and hyperbolic decline in production in the research area is 47,21,49,and 58,respectively,accounting for 26.8%,12%,28%,and 33.2%,respectively.The number of wells with hyperbolic decline is the highest.4)The remaining oil reserves in the Chang 6₁³small layer are the least,only enriched in the southeast.The remaining oil reserves in the Chang 6₂¹small layer are the largest and widely distributed.The remaining oil in the Chang 6₁²small layer is scattered in the north,with few reserves,and distributed in a patchy manner in the south.5)The distribution of remaining oil is influenced by comprehensive factors such as structure,sedimentary microfacies,and injection production relationships.In order to tap the potential of remaining oil,it is necessary to improve the injection production well network,supplement holes,and optimize injection production connectivity.In addition,the southern region of the research area is rich in remaining oil,and efforts should be made to tap the potential of remaining oil in the southern region.