Method Research Of Gas Injection In Niujuanhu Xishanyao East Reservoir

At present some oil field for the development of low permeability reservoirs mainly adopt water injection and depletion-drive development.Some oilfield due to strong heterogeneity or high start-up pressure, cause water injection difficulty and can't timely supplement energy, recovery degree is very low. Some domestic oil fields, such as Shengli,liao has already begun to explore gas injection technology. The nitrogen, steam injection,injecting CO2 gas, air, etc., received a good production effect.Research work area of this thesis is east reservoir of the three pond lake. The main contradiction existing in the development is that, such as, ratio of low production well is high;the conventional water flooding control effect is not ideal; advancing of axial channel is fast,liquid of lateral wells is low; formation pressure distribution is not balanced; viscosity of crude oil is high and oil exists emulsification phenomenon after water breakthrough .Development effect of early water injection is poorer. To effectively improve development effect, it is necessary to explore the method of gas injection. Firstly, using the latest logging interpretation results and combining with production data, this study improves the geological model for dynamic characteristics.Secondly, gas injection experiment is fitted with numerical simulation technology, and gas injection displacement medium is optimized with the typical profile model . Further, combining with revised geological model by east history matching,,orthogonal design method is used to optimize the proof gas injection reservoir engineering parameters, to forecast scheme.The results show that the hydrocarbon gas, CO2 and N2 immiscible displacement efficiency by 54.68%, 52.39% and 33.46%, respectively. hydrocarbon gas, CO2 gas injection effect is best. Subject to the restrictions of hydrocarbon gas source and the cost, medium using CO2 gas injection is most appropriate, orthogonal optimization design results of carbon dioxide gas water alternating injection parameters show that the slug size PV best is 0.002PV and the injection-production ratio is 0.8, gas injection cycle and water injection cycle are 4 months, respectively, the injection timing is present, gas water ratio of 1:2. Optimal value of total gas slug injection is between 0.008-0.012 PV. Plan prediction results show that in 2035 year the recovery degree is 2.82% higher than that of base solution, increasing 67.32×104 t oil.