X油藏注气混相驱可行性实验研究

Feasibility experimental research on miscible flooding of X reservoir by gas injection

关键词:  N₂  CO₂  饱和压力  混相驱替 

Key words:  nitrogen  carbon dioxide  saturation pressure  miscible flooding

摘要:

针对X底水油藏油井注水后综合含水上升过快的问题,利用HB70/300型高压物性分析仪开展了该区块原油相态特征实验、注气相态特征实验,并运用细管法开展了注CO₂最小混相压力实验。对比分析了CO₂和N₂两种性质气体注入前后原油的相态特征变化,确定了该区块原油注CO₂最小混相压力,为X油藏注气提高采收率可行性提出依据。实验结果表明,X油藏原始地层压力为46.01 MPa,原油饱和压力为11.06 MPa,注N₂后饱和压力上升迅速,在原始地层条件下难以实现混相,表现出典型的非混相特征；注CO₂后饱和压力上升较平缓,细管法测得的最小混相压力为28.03 MPa,说明利用CO₂可实现CO₂的混相驱替,而且最终的驱替效果比较理想。说明该油藏可开展注CO₂混相驱,为进一步的开发方案调整提供了依据和合理的建议。 

Abstract:

In order to solve the problem that the comprehensive water cut is rising too fast after water injection in X reservoir, the research has been carried out in this paper. Experiments on phase behavior of crude oil and phase behavior experiments of gas injection have been carried out by using HB70/300 high pressure physical properties analyzer. The minimum miscibility pressure of CO₂ injection has been carried out by using thin tube method. The phase behavior of crude oil has been analyzed before and after N₂ or CO₂ injection. In this paper, the minimum miscible pressure of crude oil for CO₂ injection is determined, which provides basis for EOR of X reservoir. These experiments showed that the original pressure of X reservoir is 46.01 MPa, the saturation pressure of crude oil is 11.06 MPa,which can hardly get miscible flooding by N₂ injection because the saturation pressure will rise quickly. The saturation pressure will rise gently for CO₂. The minimum miscibility pressure measured by the thin tube method is 28.03 MPa, indicating that miscible flooding by CO₂ injection can be achieved. And the ultimate displacement effect is ideal. The reservoir can be injected with CO₂ miscible flooding, which provide a basis and reasonable suggestions for adjusting development plan.