Study Of Gas Injection Development Method And Remaining Oil Distribution Law Of W Reservoir

W reservoir is a typical anticlinal reservoir with bottom water.The upper light oil reserve is 260.53×10~4t and the lower heavy oil reserve is 224.75×10~4t.W reservoir is in its middle or later phase of production and a lot of problems come out,such as production decline of the whole reservoir is sharp,water cut increases quickly,pressure maintenance is low,which has significant differences with the goal set in the beginning.It is emergent to analyze what are the problems and raise up methods to increase production.Through the method of investigation and analogy,in the condition of the construction of W reservoir,it is better to use the method of gas injection aid gravity drain to develop and in the development it is a necessary to keep the interface stable.A history matching is conducted on the actual model and the parameters of the whole reservoir and single wells all have a good matching.Based on the result of history matching,a study of remaining oil digging is conducted.It is known that in the plane,affected by the faults and sediment erosion the remaining oil is rich near the faults and the area of unconformity.Except that,the top of the construction is affected a little by the bottom water drain which usually makes a rich remaining oil.Vertically,remaining oil is affected by the interlayer and the heavy oil formation.In the next production phase it is necessary to development the remaining oil by understanding the law of remaining oil distribution and ensuring the optimized gas injection method.Based on the problem,a mechanism study is conducted and the results show keep a reasonable oil recovery rate is important factor to ensure the interface's stable during the development of gas injection.The slower of the oil recovery rate,the smaller of the oil production rate and the faster of the oil recovery rate,the gas injected in the top of the construction is easier to break through which made the production well in the lower construction quicker to produce gas.So the optimized oil recovery rate is between 1%and 2%.Through the study of model of W reservoir,it is known that the interlayer on the top of the reservoir has a significant influence to the gas injection development,so it should keep the interlayer away when inject gas.Take the factors of oil and gas interface's stability,cumulative oil production,sweep efficiency into consideration,the optimal oil recovery rate is between 1%and 2%.