| With water-flooding oil field entering the extra-high water stage(>90%),under the influence of geological conditions such as strong heterogeneity of reservoir reservoirs,complex fluid distribution and different develop modes,the heterogeneity in the degree of water flooding and the distribution of remaining oil are becoming more and more complicated.So that water-driven reservoirs meet a double challenge both in technical and economic.Therefore,an accurate understanding of residual oil enrichment mechanism and target area for enhanced oil recovery in high water cut stage has become a key problem in oilfield development that cannot be avoided.It has a very important guiding significance in promoting the secondary development of the oil field and increasing oil production.According to the characteristics of reservoir heterogeneity and displacement pressure gradient,this paper studies remaining oil enrichment mechanism and determine the critical conditions of liquid flow steering based on theoretical analysis and mathematical deduction,the relationship between pressure gradient,flow rate and seepage resistance are taken into consideration using streamline tracing method,microscopic seepage law and parallel core displacement test.Besides,the effects of pore throat structure,fluid properties and other factors on the formation of residual oil were studied by microscopic two-phase percolation theory.Based on the above research,combining with reservoir characteristics and development characteristics,this paper studies the reasons for the difference of the remaining oil enrichment patterns in the plane and vertical distribution considering geological and development conditions,it is necessary to develop the supporting technologies for different enrichment modes,which has important theoretical and practical significance for enhancing the effective utilization of remaining oil and slowing down the production decline. |
PDF Full Text Request