Abstract: Unconventional oil and gas,represented by shale oil and gas and low-permeability tight oil and gas,are important replace-ment resources in China.Due to their poor reservoir properties,effective exploitation is difficult.Currently,reservoir transformation is mainly carried out through horizontal well volume fracturing technology.However,there are still problems such as water resource waste,reservoir damage,and poor increasing production.Because of the the low viscosity,high density,and high diffusivity,super-critical/liquid CO2 can quickly enter reservoir micropores and microfracture.CO2 fracturing can effectively reduce fracture pressure,form complex fracture networks,increase formation energy,improve backflow rate,reduce reservoir damage,and achieve single well production increase.It is suitable for efficient and green exploitation of unconventional oil and gas resources.This paper introduces the basic research progress of CO2 fracturing from the aspects of the mechanism of rock breaking and fracture making by CO2 fracturing,the mechanism of influence of CO2 on rock properties,the flow characteristics of CO2 fracturing wellbore,CO2 fracturing stimulation and geological storage,and briefly describes the development and application of several main fracturing technologies,including CO2 foam fracturing,CO2 dry fracturing,CO2 acid fracturing,and CO2 mixed fracturing.Against the background of China's current"dual carbon"goals and increased exploration and development efforts for unconventional oil and gas resources such as shale oil and gas,CO2 fracturing technology is one of the key core technologies for building a clean,environmentally friendly,low-carbon,and efficient energy security and development technology system,with great potential for development and promotion.

Key words: Carbon dioxide, fracturing, unconventional oil and gas, basic research, technological development

摘要： 以页岩油气、低渗致密油气为代表的非常规油气是我国重要的接替资源,由于其储层物性差,有效开采难度大,目前主要通过水平井体积压裂技术进行储层改造,但依然存在水资源浪费、储层伤害大及增产效果一般等问题.超临界/液态CO2 具有低粘度、高密度、高扩散性等特性,能够快速进入储层微孔隙、微裂缝中,CO2 压裂可以有效降低破裂压力,形成复杂缝网,同时地层增能,提高返排率,降低储层伤害并实现单井增产,适用于非常规油气资源的高效、绿色开采.本文从CO2 压裂破岩造缝机理、CO2 对岩石性质影响机制、CO2 压裂井筒流动特性及CO2 压裂增产与地质封存作用等方面介绍了CO2 压裂基础研究进展,对CO2 泡沫压裂、CO2干法压裂、CO2 酸化压裂和CO2 混合压裂几种主要压裂技术的发展和应用进行了简要阐述.在目前我国"双碳"目标和加大页岩油气等非常规油气资源勘探开发力度的背景下,CO2 压裂技术是构建清洁环保、低碳负碳的能源安全、高效开发技术体系的关键核心技术之一,极具发展和推广应用潜力.

关键词: CO2, 压裂, 非常规油气, 基础研究, 技术发展

CLC Number: 

• TE35