| In this paper, the research content from sinopec jiangsu oilfield development research, volatile oil reservoir in Xuwen N2and gas injection development process phase characteristics, formation fluid dynamic by gas injection as the main research object, the feasibility to carry out the volatile oil reservoir gas injection development rule, in the process of gas injection fluid phase state characteristics change and so on basic research work, to determine the injected gas in the process of gas injection and volatile oil underground form, correct understanding of formation fluid in the process of volatile oil system during gas injection phase state characteristics change rule.The Xuwen volatile oil reservoir found reasonable development mode has very important significance. The conclusions obtained from related work are as follows:(1)The formation fluid belongs to the weak light fluid composition of volatile oil.Formation system of oil and gas bubble point pressure is low, to satisfy the differential pressure is bigger, crude oil is not easy to take off the gas, can be mining failure for a period of time.(2)For dissolved gas oil is better than high volatile oil reservoir fluid, when the reservoir pressure drop to below the bubble point pressure, a large amount of dissolved gas escape, its mobility than oil phase, make the most of the oil phase in formation, then the production status for a large number of gas carrying part of crude oil, condensate oil output, this situation is similar to the production performance of condensate gas reservoir, so the dissolved gas oil ratio high volatile oil reservoir can be considered constant volume failure experiment.(3)Volatile oil reservoir non equilibrium constant volume failure experiments show in volatile oil reservoir, when the outside temperature and pressure changes at a faster rate than phase change speed, intermediate hydrocarbon components in the volatile fluid could evaporate to residual in residual oil liquid, the gas phase and the residual oil volume change small, lower shrinkage rate.(4)Formation of crude oil system N3multiple contact miscible injection pressure is about31.75MPa, the multiple contact miscible gas injection pressure is about22MPa, lower than the original formation pressure (27.28MPa), through the pseudo ternary phase diagram simulation results analysis found that:from the point of gas liquid two phase multistage contact process, the heavy components of liquid shrinking in the injected gas C2-C6intermediate hydrocarbon components increase gradually.Simulation shows that by injected gas and crude oil contact many times, can evaporate or extraction crude of intermediate hydrocarbon reservoir, the injected gas enrichment, is a typical multiple contact miscible gas flooding of evaporation.(5)Thin tube from N2and hydrocarbon gas injection flooding experiment can be seen that volatile oil reservoir Xuwen6-1above20.4MPa hydrocarbon gas injection miscible flooding can be realized, and N2injection requires more than30.3MPa (more than the original formation pressure) can achieve miscible flooding. Therefore, in the original formation pressure under the condition of volatile oil reservoir Xuwen6-1note N2can only achieve near miscible flooding.(6)Long-core shows that:the original formation pressure under continuous flooding recovery degree is40.51%, eventually effect is relatively poor; Under the original formation pressure pulse gas injection flooding the ultimate recovery degree is62.93%, the highest recovery degree; Failure to saturation pressure pulse gas injection flooding recovery degree is31.03%, eventually shows that under the original formation pressure pulse gas flooding development approach is superior to the failure to saturated pressure pulse gas injection flooding; Under the original formation pressure pulse nitrogen gas injection flooding recovery degree is26.22%, eventually effect is the worst, failure to saturation pressure pulse nitrogen gas injection flooding recovery degree is32.68%, eventually that failure to saturation pressure pulse nitrogen gas injection flooding development approach is superior to the original formation pressure pulse nitrogen gas injection flooding.Gas injection timing should be early gas injection pressure maintenance development.(7)Considering the effects of artificial fracture mechanism of injection timing one-dimensional numerical simulation analysis shows that the original pressure betting associated gas flooding, recovery degree, the highest can amount to90%, injection multiples of0.8PV injected gas breakthrough.And when the failure to12MPa gas injection pressure, recovery degree decreased to40%, injection multiples of0.4PV injection gas began to break.The original bet N2gas drive pressure, recovery degree of up to70%, injection multiples of0.55PV injected gas breakthrough.And when the failure to12MPa gas injection pressure, recovery degree decreased to60%, injection multiples of0.3PV injection gas began to break.Therefore, Xuwen area volatile oil reservoir should be taken early gas injection development way.Therefore,according to the reservoir conditions and the actual situation,Xuwen area volatile oil reservoir should be taken early gas injection development way and miscible flooding by hydrocarbon should be considered, the recovery of injecting gas and soaking for a period of time can be greatly improved.We recommend the development method of using hydrocarbon gas injection and soaking. |
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