新疆油田低渗透区块空气驱实验研究

Experimental Study of Air Injection for IOR in Low Permeability Reservoir of Xinjiang Oilfield

低渗透油藏由于地层能量衰竭较快且注水困难,一次及二次采收率较低,故考虑采用注空气技术来维持地层压力、提高采收率。相对于其他气驱技术,空气驱具有来源广、成本低的显著优势。通过对C-9井区原油低温氧化实验及空气驱实验,研究了目标区块原油的低温氧化特性及油藏条件下的空气驱提高原油采收率幅度。主要从注空气安全和提高采收率潜力方面评价了空气驱低温氧化工艺的可行性。实验结果表明,在相对低温条件下C-9区块原油可以有效消耗氧气,即使氧化速率缓慢,但是考虑空气在油藏中滞留时间及氧化反应的热效率,仍可以保证注气安全,空气驱二次采油可以得到较高的采收率,但是对于剩余油饱和度低的三次采油,空气驱提高采收率的幅度相对较低。

Primary production and water flooding experience of low permeability reservoirs have demonstrated that the recovery factor in these reservoirs is very low due to lack of reservoir energy and poor water injectivity.Air injection has been optioned as an alternative secondary or tertiary technique to maintain reservoir pressure and increase sweeping and displacement efficiency.Compared with other kinds of gas flooding technology,air flooding has significant advantages of wide sources and low cost.Low temperature oxidation（ LTO） characteristics of oil sample in C-9 unit and IOR efficiency at reservoir conditions were studied through LTO experiments and air flooding experiments.The feasibility of air injection via a LTO process has been evaluated in terms of air injection safety and IOR potential.The results of the experiments indicate that O2 could be consumed effectively by oil sample in C-9 unit at reservoir temperature.Even if the oxidation rate was slow,the safety of the air injection could be ensured in consideration of the air retention time in the reservoir and thermal efficiency of oxidation reaction.Relatively high oil recovery factor could be got in secondary oil recovery by air injection.The recovery efficiency amplitude of air flooding was relatively low when the technology was applied in the low oil saturation reservoir for tertiary oil recovery.