含酸气挥发油藏回注溶解气对原油相态与物性的影响

含酸性气体(H_2S和CO_2)的挥发油藏选择回注溶解气开发,既能减缓压力衰竭,又可以节省酸气处理费用。但回注含酸气组分的溶解气对原油相态与物性影响规律尚不明确,进而制约了注气开发效果的预测和注气组分的优化。以国外某挥发油藏为例,在组分划分和PVT实验拟合的基础上通过模拟注气膨胀实验研究了溶解气及H_2S和CO_2等主要气体组分对原油相态与物性的影响规律。结果表明:溶解气中的H_2S和CH_4对原油p-T相图影响显著,而CO_2和溶解气对原油p-T相图影响很小;酸性气体除降黏能力低于CH_4以外,在降低原油饱和压力、降低原油挥发性和膨胀原油体积方面均强于CH_4;含酸气挥发油藏回注溶解气有利于提高增油效果。

Influence of solution gas reinjection on oil phase behavior and physical properties for volatile oil reservoir with acid gas dissolved in

Solution gas reinjection is an effective development method for volatile reservoir with rich H2S and CO2 dissolved in to reduce pressure depletion and save expense of acid gas process. However, the influence of reinjection of solution gas with acid gas components on oil phase behavior and properties is not yet clear. This restricts the prediction for production performance and optimization for reinjection gas composition. Taking an oversea volatile reservoir as case study, this paper first regressed PVT data and recombined components, then studied the influence of reinjection of solution gas and its major gas components (H2S, CO2, etc.) on oil phase behavior and properties on the basis of swelling simulations. The results show that H2S and CH4can greatly impact the P-T phase diagram of oil while CO2 and solution gas has little influence on that; the acid gas components are more effective than CH4 on reduction of oil saturation pressure and volatility and on increase of oil swelling except for viscosity reduction; solution gas reinjection is of benefit to enhancement of oil recovery for volatile reservoir with rich acid gas dissolved in.