| The delta front subfacies sand body of K1h23-4 oil reservoir in A9 well block of an L oilfield in Xinjiang is mainly composed of underwater distributary channel microfacies.The sand body thickness is relatively stable,and its distribution is widespread and continuous.It belongs to a typical reservoir with high porosity and permeability.Since it was put into development in 2001,it has entered an extremely high water cut stage after undergoing corresponding injection production relationship adjustments such as basic well pattern development,edge expansion adjustment,and microbial flooding.In the later stage of development,the dominant seepage channels in the reservoir develop,resulting in ineffective circulating water injection and poor reservoir heterogeneity,resulting in an accelerated water cut rise rate after water breakthrough in the oil well.In response to the above problems,this paper proposes a microbial mineralization profile control and flooding technology,which utilizes urease secreted by mineralizing microorganisms to decompose urea and generate calcite precipitation with calcium ions,thereby blocking the dominant seepage channels,achieving the goal of improving water absorption profile,expanding the swept volume of medium and low permeability reservoirs,and further improving oil recovery after water flooding.According to the characteristics of rapid precipitation of calcium carbonate induced by microorganisms,high calcite content and excellent cementation strength,indoor physical simulation experiments of microbial mineralization were carried out,and the p Agging and flooding effects of microbial mineralization system were eva Aated by sand filling pipe and sand filling model.The experimental results show that when the p Agging times reach 4 times,the p Agging rate can reach 83.53 %,and the downward trend of permeability slows down.When the permeability is about1000 m D,the p Agging rate can reach 93.29 %,and then the p Agging effect becomes worse with the increase of permeability.And as the permeability difference increases,the reservoir heterogeneity becomes worse,and the reservoir profile improvement rate gradually becomes worse.The optimal injection vo Ame of the microbial mineralization system is 0.3PV,the optimal flooding time is 70 %,the optimal flooding times are 3times,the final recovery rate is 43.18%,and the recovery rate is 8.31 % higher than that of water flooding,indicating that the microbial mineralization system can block the dominant seepage channel,and the remaining oil is used more.Based on the precise geological model of the target block,historical matching is carried out in combination with reservoir numerical simulation software,and the overall and single well matching rate reaches over 80%.Due to the development of edge and bottom water in the reservoir,the western region in the lower part of the reservoir is severely flooded,and the upper part of the reservoir is not washed with water.The distribution of oil and water has significant gravity differentiation.Therefore,the remaining oil in the entire reservoir is mainly distributed in the western region in the upper part,while the lower part of the reservoir is mainly distributed in the eastern region,presenting a relatively scattered overall but relatively concentrated local law.By establishing microbial mineralization parameters,selecting typical well groups,and conducting numerical simulation injection parameter research for microbial mineralization profile control and flooding,the optimal injection amount of the microbial mineralization system is determined to be 0.3PV.The sooner the injection timing is,the better.The injection method is divided into three stages,with a cumulative increase of 62800 tons of oil in each stage,a decrease in water content of 4.595%,a stage increases in recovery of 3.71%,and a final recovery rate of 42.88%.It provides guidance for the field implementation of microbial mineralization profile control and flooding pilot test in well block A9. |
PDF Full Text Request