Research On Optimization Of Associated Gas Injection Parameters For M Reservoir

With the exploration and development of oil reservoirs,most oilfields in China have entered the middle and late stage of high water cut after water injection development,and the final recovery rate of water flooding can only reach 30-40%,and nearly 2/3 of geological reserves are stored underground.In order to improve oil recovery,gas injection has become an important technique to develop high water content reservoir.In this paper,based on the actual production situation of M reservoir,a model is established for the selected area to study the mechanism of hydrocarbon injection and gas flooding.The gas injection parameters were optimized by using the component model adjusted by historical fitting.Through the research,the following conclusions are drawn:(1)The volume coefficient saturation pressure,the original dissolved gas-oil ratio,the viscosity and the density of surface degassed crude oil were obtained by the fluid phase state fitting of M reservoir.Thin tube displacement experiment shows that:with the gradual increase of oil pressure in reservoir M,the better the displacement effect is,and the minimum miscible pressure of associated gas injection can reach 34.2mpa.With the increase of injected gas heavy hydrocarbon,the displacement effect is better and the minimum miscible pressure decreases.The long core displacement experimental fitting shows that continuous gas injection can achieve a higher degree of recovery at different gas injection rates in M reservoir.(2)By studying the characteristics of gas-driven state in M reservoir,the results show that the injector group has good connectivity and gas injection can effectively increase the oil production of the affected well.(3)Gas injection model was established and historical fitting was carried out.According to this model,the remaining oil in the formation could not be effectively used due to the prediction of continued waterflood development for 33.5 years with 103.67 104t increased oil production and 4.19%increased recovery degree.(4)To optimize the parameters of the established model,such as gas injection well type,gas injection intensity,pressure,gas injection composition,gas channeling gas-oil ratio and gas injection life,and recommend a set of reasonable design scheme.According to the recommended scheme of this design,oil production increased by 296.19 104t in 33.5 years,and the recovery degree increased by 11.97%.Through this numerical simulation study,it can be concluded that gas injection can effectively improve the recovery of M reservoir,which is of great significance to the development of similar reservoirs.