Study On Main Control Factors In Development Of Thick Carbonate Reservoir And Their Optimization

The typical carbonate reservoir MB in the Middle East is geologically characterized by large reservoir thickness,strong heterogeneity,obvious anisotropy,and the variations in its development dynamic characteristics such as exploitation interval,production system and engineering technology have resulted in such problems as large differences between yields of different wells,rapid decline in their output,and rapid rise in water cut in some wells.However,it is not clear which factors have a greater impact on its development and production effect among many factors.Therefore,it is necessary to further analyze the main controlling factors of the development effect of this type of reservoir,study the influence laws of various factors,optimize and adjust the follow-up reservoir development plan according to the research results.Therefore,it is necessary to further analyze the factors which control and influence the development effect of this type of reservoir,to figure out the distribution law of remaining oil and to determine the plans for optimization and adjustment of its follow-up development plans.Based on MB reservoir geology and development data,with the comprehensive effect index of single well development defined on actual production data,this thesis preliminarily analyzes the correlation between various influencing factors and the index,and uses random forest method to decide the main factors controlling the development effect of a single well in the reservoir of thick carbonate.After that,the numerical simulation method is used to further analyze the various factors influencing the development effect of the typical well area by establishing a typical well area model with area samples representative of reservoir and parameters included in.Then,through the establishment of the overall numerical model of the reservoir,research of the distribution law of remaining oil in each oil layer,and summary of the distribution pattern of remaining oil,this thesis proposes plans for optimization and improvement of reservoir development,predicting their outcomes and determine the best improvement plan.The study found that:(1)The development effect of a single well in a thick carbonate reservoir is mainly affected by five types of geological and engineering factors,namely the effective thickness of the oil layer,the length of the perforation section,the oil saturation,the initial formation pressure,and the porosity.(2)The influence degree and law of different geological and engineering factors on the development effect of typical well areas are different.The parameter combination that is most conducive to improving the development effect of typical well areas can be obtained by studying the influence laws of various factors,i.e.infill well pattern and water injection development.(3)Longitudinally,Layer MB21-1 ～ 3 have more remaining reserves and lower recovery degree,so they are the remaining oil accumulation area.Horizontally,more remaining oil is concentrated in the structural highs.According to its origins,the remaining oil is divided into six distribution modes:structural high position type,imperfect injection-production type,interlayer control type,gravity differentiation type,bottom water coning type and edge water propulsion type.(4)The results from the predictions of the development adjustment plan indicate that the comprehensive development plan has the highest recovery degree,the slowest production decline rate and relatively low water content,which is the optimal development adjustment plan.