注气驱油技术发展现状与启示

Status and enlightenment of international gas injection EOR technology

我国注气驱油提高采收率技术发展较晚,且存在注CO2与氮气谁更优的争议。根据国内外10a来注气开采发展的相关数据,从储层岩性、储层渗透率、储层深度、温度、原油饱和度、黏度等方面分析了国内外注气技术的发展状况。分析结果表明:发展注CO2提高采收率技术具有广阔的应用前景;受温室气体减排的影响,国际上注CO2驱油项目主要以注气混相驱发展最快,而我国注气试验主要采用商品CO2气,并且存在混相困难的问题;碳酸盐岩油藏注气项目超过砂岩油藏,而传统认为碳酸盐岩油藏具有裂缝,注气要窜,故不适合注气开采;国际上在砂岩油藏注气开采的渗透率并不是太低(大于10×10-3μm2),而我国注气试验都是超低渗透率(小于10×10-3μm2);多数油藏是在注水后再进行注气,而过去认为注水后对注气效果不利;国外注空气目前主要采用高温氧化开采轻油,而不是稠油,而传统认为热采适合于稠油。针对我国目前注气情况和国外发展趋势,就如何开展注气驱油工作提出了建议。

China lags behind the world in the gas injection EOR technology and injecting carbon dioxide or nitrogen is still a controversy at present.On the basis of the related data from the past ten-year development of gas injection in the EOR technology at home and abroad,we analyze the status of this technology in aspects of reservoir lithology,reservoir permeability,reservoir depth,reservoir temperature,crude oil saturation and oil viscosity,etc.Results are presented here as follows:①The international gas injection projects are mainly CO2 miscible flooding whose development is the quickest due to the impact of international greenhouse gas emissions.However,in China gas injection tests mainly use merchandise CO2 gas,and miscible flooding is difficult.②At present,the number of gas injection projects in the carbonate reservoirs surpasses that in sandstone reservoirs,while in traditional view,carbonate reservoirs with fractures are not suitable to gas injection.③Internationally the permeability of sandstone reservoirs applying gas injection is not very low(>10×10-3 μm2),but in China the permeability of experimental reservoirs using gas injection is mainly ultra-low(<10×10-3 μm2).④Most reservoirs carry on gas injection after water flooding,but we traditionally consider that the effect is not good.⑤Currently,air injection is mainly used to oxidate light oil rather than heavy oil at high-temperature,while the traditional view is that thermal recovery is suitable for heavy oil.In view of current situation of gas injection in China and the overseas development trend,suggestions are made on how to develop gas injection.