Abstract: The utilization and storage of CO₂ in oil and gas production processes is a crucial component of CO₂ capture, utilization, and storage (CCUS) technology, and represents a key strategic priority for China’s energy transition. China’s abundant unconventional oil and gas resources, including tight and shale reservoirs, present unprecedented opportunities for the CO₂ utilization and storage technologies. This also provide a critical breakthrough for balancing energy security with carbon reduction. The paper systematically reviews the progress in fundamental research on CO₂ utilization (including fracturing, enhanced oil recovery (EOR), enhanced gas recovery (EGR)) and storage in tight/shale oil and gas reservoirs over the past decade, enhancing the understanding of the underlying mechanisms. Based on a summary of field practices, the targeted future research directions are outlined as below:(1) CO₂ fracturing can reduce breakdown pressure and increase fracture complexity; however, the mechanisms of CO₂ storage remain incompletely understood. The primary challenges for CO₂ fracturing and storage include increasing viscosity and carrying sand, controlling the formation and expansion of fracture networks, and process design. (2) CO₂-EOR mainly relies on the CO₂-water-crude oil-rock interactions and miscibility effect, and CO₂ diffusion is critical for hydrocarbon recovery in tight matrix-fracture structure reservoirs. The storage mechanisms primarily encompass four types:structural trapping, capillary trapping, dissolution, and mineralization. Future research will focus on nanoconfined phase behavior, miscibility mechanisms, gas channeling control, and sweep control methods. (3) CO₂-EGR can improve shale gas recovery through the main mechanisms involving competitive adsorption, pressure maintenance, and inhibition of water invasion. Simultaneously, CO₂ storage is achieved through four mechanisms:dissociation, adsorption, dissolution, and mineralization. However, the mechanisms of multiphase interactions, complex phase behavior characteristics, and long-term evolution pattern during CO₂ storage still require further exploration. Currently, the integrated design and multi-objective optimization methods for CCUS are not yet fully developed, and cannot provide precise guidance for field-scale applications. It is imperative to advance research on mass transfer mechanisms during near-miscible/miscible displacement and multiple-contact mass transfer, develop effective methods for controlling preferential pathways and sweep efficiency, and establish a quantitative evaluation and monitoring system for the long-term evolution of CO₂ storage. These efforts are essential for effectively promoting the application of CCUS technologies in the exploitation of tight and shale oil and gas resources.

Key words: tight/shale oil and gas, CO₂ fracturing and storage, CO₂ enhanced oil recovery and storage, CO₂ enhanced gas recovery and storage, research progress, field practice

摘要： CO₂在油气开采过程中的利用与封存是CO₂捕集、利用与封存技术的重要组成部分,也是中国能源转型的关键布局方向。中国致密/页岩等非常规油气资源丰富,为CO₂利用与封存技术应用带来前所未有的机遇,也为平衡能源安全与碳减排找到突破口。系统梳理了10年来国内外致密/页岩油气储层CO₂利用(压裂、驱油及驱气)与封存方向的基础研究进展,深化了机理方面的认识。总结了矿场实践案例,针对性地提出未来主要研究方向:①CO₂压裂可以降低破裂压力,增加裂缝复杂程度,但封存机理尚不完全清楚;增黏携砂、缝网形成与扩展控制、工艺设计是CO₂压裂与封存面临的主要问题。②CO₂驱油主要利用CO₂—水—原油—岩石相互作用机制及混相效应,CO₂扩散作用在致密基质-裂缝结构储层发挥重要作用;封存机制主要包括构造、束缚、溶解和矿化4种;限域空间相行为、混相机制、气窜治理及波及控制方法等是未来主要研究方向。③CO₂驱气可通过竞争吸附、维持压力、抑制水侵等主要机理提高页岩气采收率,同时通过游离、吸附、溶解和矿化4种机制实现封存;多相间相互作用机制、复杂相态特征及长期封存演化规律仍需深化。CO₂利用与封存一体化设计及多目标优化方法目前尚不成熟,无法准确指导矿场应用,亟须深化近混相/混相与多次接触传质机理研究,发展优势通道控制与波及体积调控方法,构建CO₂长期封存演化定量评价与监测体系,以切实推动CO₂利用与封存技术在致密/页岩油气资源开采过程中的应用。

关键词: 致密/页岩油气, CO₂压裂与封存, CO₂驱油与封存, CO₂驱气与封存, 研究进展, 矿场实践