A Research Of The Method To Identify And Quantify Large Pore Channel In Wu-4District Of Wunan Oilfield

After a long period of water flooding washed out, and the long-term water erosion makes great changes have taken place in reservoir structure, a high permeability channel gradually formed between oil and water Wells, serious large pore was created in the water flooding reservoir. In the micro level, large pore is the cause of formation of clay minerals denudation and the change of fluid seepage way. In macro perspective, large pore caused the sharpening contradictions between the layers, increasing reservoir heterogeneity, water injection of inefficient or ineffective circulation greatly reduces the utilization rate of water injection. This article through the analysis of development characteristics, it shows the Wu-4wells group entered the stage of high water in Wunan oilfield. Through further analysis of the main oil layer sedimentary condition and pore-permeability structure characteristics, beginning to recognize the possibility of the formation of large pores in the reservoir. Comprehensive water cut, water cut rising rate, water use efficiency and connectivity between Wells show that wells have good properties, large pore widely exists in wells that have a good connectivity, and these Wells moisture content up to80%.The wells and layers with low efficiency circle have to been controlled by measures such as profile control or water plugging and so on, so as to improve the effect of water flooding, and the key is to recognize them.On the basis of the comprehensive research literature, the article explains the mechanism of Influence the formation of large pores from two aspects of geology and development. Based on development data, has been clear changes of comprehensive water cut and water cut rising rate, and the brief analysis between the injection-produc-tion well connectivity was made by using the theory of grey correlation and logging interpretation conclusion, thus formed a preliminary understanding of large pore.Through a comprehensive analysis of the geological features and development data of Wu-4block to determine the static and dynamic index that affecting the formation of large pore, and combined with the theory of fuzzy comprehensive evaluation and analytic hierarchy process to establish the identification system of large pore of Wu-4block, and to determine the index weight and membership functions. Raised the three-level classification standard of reservoir conditions, and application identification system has carried on the classification for oil and water Wells reservoir conditions, so as to achieve the purpose of identifying large pore. Based on percolation theory and fuzzy mathematics method, excess water between wells were splitting to determine the split coefficient of production well, and then large pore volume calculation formula were determined. The fluid flow was regarded as flow one-dimensional linear flow, deduced the calculation formula of permeability. Application Carman-Kozeny equation determined the formula of a large pore throat radius. Finally, based on "c#" high-level programming language, a large pore identification and parameter calculation system is developed for water injection reservoir.