致密油藏CO₂驱气溶性表面活性剂的研究进展

Research Progress on Gas-Soluble Surfactants for CO₂ Flooding in Tight Oil Reservoirs

摘要: 如今我国常规油藏动用程度大，剩余额度少，以致密油藏为代表的非常规油藏逐渐成为油藏的主要开发生产对象，而将CO₂注入致密油藏内进行CO₂驱油是常用的方法之一。一方面能充分利用二氧化碳在溶气及降黏方面可以提升油藏采收率的优点，另一方面也可以达到CO₂封存的效果，缓解地球变暖的问题。但是由于我国大部分致密油产区的地层压力相对偏低，无法实现CO₂混相驱，导致开发效果并不理想。与此同时，在致密油藏CO₂混相驱的开发过程之中，气溶性表面活性剂对其开发而言起到的作用至关重要，因此该文对于气溶性表面活性剂的一些性质，诸如它需要符合表面活性剂与CO₂之间相互作用的相关机制等方面的有关知识进行了详细阐述，并且指出了在对分子结构设计的时候应该考虑到一些亲油亲水平衡以及稳定性方面的核心准则。另外，在微观层面来说，还应该看到的是表面活性剂通过减小界面张力，提高流度控制能力以及改善扩散传质等机制去优化CO₂驱油效果，在这个问题上而言还有很多的工作尚待完成，但CO₂高温高压力稳定性还是有待突破的。最后还阐述了环保型表面活性剂的开发，需要根据可再生原料、低毒设计的理念去布局方向，这样未来会更为侧重可持续发展，重视多功能一体化，这种设计思想的研发与构架能够促进高性能气溶性表面活性剂的设计与开发。

Abstract: Nowadays, the utilization degree of conventional oil reservoirs in China is high, and the remaining reserves are small. Unconventional oil reservoirs represented by tight oil reservoirs have gradually become the main targets for oil reservoir development. Injecting CO₂ into tight oil reservoirs for CO₂ flooding is one of the commonly used methods. On the one hand, it can make full use of the advantages of carbon dioxide in enhancing oil recovery in terms of gas dissolution and viscosity reduction; on the other hand, it can also achieve the effect of CO₂ sequestration and alleviate the problem of global warming. However, due to the relatively low formation pressure in most tight oil producing areas in China, CO₂ miscible flooding cannot be realized, resulting in unsatisfactory development effects. At the same time, in the development process of CO₂ miscible flooding in tight oil reservoirs, gas-soluble surfactants play a crucial role in its development. Therefore, this paper elaborates in detail on some properties of gas-soluble surfactants, such as the relevant knowledge about the mechanism of interaction between surfactants and CO₂, and points out that some core criteria regarding lipophilic-hydrophilic balance and stability should be considered in the design of molecular structure. In addition, at the micro level, it should be noted that surfactants can optimize the effect of CO₂ flooding through mechanisms such as reducing interfacial tension, improving mobility control ability, and enhancing diffusion and mass transfer. There is still much work to be done in this regard, but the stability of CO₂ under high temperatures and high pressures remains to be broken through. Finally, it is expounded that the development of environmentally friendly surfactants needs to be laid out in accordance with the concepts of renewable raw materials and low-toxicity design. In this way, more emphasis will be placed on sustainable development and multi-functional integration in the future. The research and development and framework of this design idea can promote the design and development of high-performance gas-soluble surfactants.