CGUS is critical to achieving deep decarbonization under global carbon neutrality targets. The Intergovernmental Panel on Climate Change (IPCC) estimates that excluding CCUS would increase the cost of limiting warming to 2˚C by 138% [6] , while the IEA underscores CGUS’s role in delivering 15% of global emission reductions by 2070 [3] . By injecting captured CO₂ into deep saline aquifers or depleted reservoirs, CGUS offers vast storage potential (8 - 55 trillion tons globally) and long-term stability. However, with 2020 storage accounting for just 0.1% of emissions, significant barriers to technology transfer and commercialization persist, necessitating urgent ecosystem restructuring [4] .

The oil and gas sector, responsible for 5.1 billion tons of carbon emissions in 2022 (13.8% of global energy-related emissions), faces intense pressure to decarbonize [7] [8] . CGUS serves as a dual-purpose solution: (1) Emission Reduction and Efficiency: CO₂-EOR integrates storage with enhanced oil recovery, producing low-carbon oil and creating a profitable closed loop [9] . (2) Business Diversification: Leveraging geological and engineering expertise, oil companies can offer carbon storage services to high-emission sectors like cement and steel, while exploring markets such as blue hydrogen and carbon removal credits [10] . This dual approach mitigates stranded asset risks and fosters new revenue streams, enabling a transition from traditional energy providers to comprehensive carbon management entities.

The global oil and gas industry is prioritizing CGUS, adopting a dual strategy of onshore EOR storage and offshore saline aquifer storage. Saline aquifers, representing 98% of global storage capacity, are a competitive focus, while depleted reservoirs, supported by established geological data, dominate early projects [4] [11] . The sector is characterized by rapid technological advancement and scaling efforts.

Leading oil companies are establishing dominance through integrated value chains and innovative business models ( Table 1 ). Chevron’s Gorgon project in Australia, the largest operational saline aquifer storage facility, has stored over 7 million tons of CO₂, targeting 25 million tons annually by 2100. ExxonMobil, utilizing a 1500-mile CO₂ pipeline network, has formed a dedicated carbon management division to deliver end-to-end capture, transport, and storage services [12] . Shell’s subscription-based storage model supports 12 projects in regions like the North Sea, aiming for 25 million tons/year by 2035 [13] . TotalEnergies, through strategic acquisitions, and bp, with its CCUS-low-carbon energy model, are advancing cross-border and industrial decarbonization initiatives, targeting significant capacity by 2030-2035. These international oil companies have been leading the transition to low-carbon energy and the development of the CCUS industry. They have successfully commercialized CCUS in a variety of geological and regulatory contexts, offering valuable, transferable lessons for China. These include advanced monitoring technologies and scalable business models that can be adapted to China’s complex geological basins and its rapidly expanding carbon market. Europe’s transnational CCUS deployment (such as the North Sea project) emphasizes international cooperation and can inspire China’s inter-provincial coordination, such as the CCUS clusters in East China and North China.

Chinese firms are advancing full-chain CGUS deployment. CNPC’s Songliao Basin project has injected 1.592 million tons of CO₂ by 2023, targeting 3 million tons/year by 2025. Sinopec’s Qilu Petrochemical-Shengli Oilfield project, China’s first million-ton-scale CCUS initiative, operates a 100-km CO₂ pipeline and is exploring a 10-million-ton cluster in East China. CNOOC’s Enping 15-1 project has stored over 1.5 million tons, with plans for a 10-million-ton offshore cluster, marking progress in offshore storage industrialization.

CGUS involves multiple processes, including CO₂ capture, transportation, and geological utilization and storage. While CO₂ capture benefits from several established technologies, the cost of capturing low-concentration CO₂ remains prohibitively high, estimated at 300 - 900 CNY/ton for sources like coal-fired power plants and steel mills [14] . Transportation primarily occurs via pipelines, tankers, or ships, with costs ranging from 0.9 - 1.4 CNY/(ton·km) [15] . The geological utilization and storage phase includes critical steps such as reservoir selection, storage potential assessment, drilling optimization, and leakage monitoring, with ongoing advancements enhancing both safety and economic feasibility. Currently, the various technologies underpinning CGUS are at different stages of maturity ( Figure 1 ). This article will introduce the technological progress related to geological utilization and storage.

Reservoir properties such as porosity and permeability are key to determining storage capacity. Caprock integrity, including its continuity and faulting, ensures long-term CO₂ containment. Regional planning focuses on caprock macro-characteristics, while engineering phases emphasize reservoir injectivity and caprock sealing capacity [16] . International standards, such as those in the USA and Australia, integrate capacity, injectivity, and economics into evaluation frameworks [17] - [19] . Due to China’s complex basin structures and lower crustal stability, the China Geological Survey has developed a preliminary geological suitability grading system tailored to different reservoir types [20] [21] .

Accurate assessment is essential for effective storage planning. International frameworks involve four stages—national screening, basin evaluation, site characterization, and application—using geological and safety risk indicators. Methods like the CSLF “Pyramid Model” and US-DOE/USGS volumetric balance estimate storage capacity but often overlook dissolution trapping mechanisms [22] - [24] . In China, the RIPED & CUP method has been adapted to include CO₂ dissolution effects for continental reservoirs. However, challenges remain in determining staged recovery rates accurately, limiting its wider use [25] [26] .

Advancements in drilling and completion technologies enhance the safety, cost-effectiveness, and scalability of CO₂ storage. Optimized well designs—such as vertical, horizontal, and clustered multi-well configurations—improve reservoir coverage and injection efficiency [16] [27] . Gas-lift reverse circulation and air-foam drilling reduce time and costs in complex formations. Nanomaterial-enhanced cement slurries and dynamic sealing improve wellbore integrity and microfracture sealing. Corrosion protection is strengthened through anti-corrosion casings, advanced coatings, inhibitors, and smart safety systems for real-time risk monitoring [28] . These integrated technologies support the safe and commercial-scale deployment of CO₂ storage.

The prevention and control of CO₂ leakage in geological storage depend on a comprehensive, full-lifecycle monitoring system. CO₂ migration can cause environmental risks like soil acidification, groundwater contamination, and ocean acidification. Measurement-Monitoring-Verification (MM&V) technologies are vital for tracking subsurface CO₂ behavior and preventing leaks [16] [28] . The monitoring framework is composed of three main components. Environmental monitoring involves techniques such as lidar and isotopic tracing to detect atmospheric and near-surface anomalies. Safety monitoring includes microseismic surveillance and wellbore integrity assessments to ensure operational safety. Migration monitoring relies on methods like time-lapse seismic imaging and vertical seismic profiling to track CO₂ movement underground [15] [16] [29] . Monitoring is conducted throughout the entire project lifecycle. It begins with baseline assessments, continues through operational tracking, and extends into post-closure monitoring. Different technologies are applied at each stage. For example, downhole sensors are commonly used during the injection phase, while satellite-based remote sensing is more suited to post-closure surveillance. The integration of these techniques effectively mitigates leakage risks and ensures the long-term stability of CO₂ storage systems.

Global policies drive CCUS industrialization through carbon pricing, tax incentives, and infrastructure investment. The U.S. 45Q tax credit provides $35/ton for EOR and $50/ton for geological storage [30] . Norway’s carbon tax (590 - 2000 NOK/ton) supports Sleipner’s saline storage [31] . The UK’s £1 billion fund targets four storage hubs by 2030, and the EU’s Horizon program backs cross-border infrastructure. Global CCUS investment exceeded $6 billion by 2023 [32] . China’s CCUS policy began with the 2008 climate strategy, added CCUS to green financing in 2020, and mandated low-cost innovation and demonstrations in 2021. These policies enabled the Qilu-Shengli million-ton CCUS project, supporting dual-carbon goals [5] [33] .

Standardized accounting and technical frameworks ensure emission reduction credibility. Internationally, the IPCC’s 2006 Guidelines outline carbon accounting for CCUS, while the CO₂ Capture, Transport, and Storage Technical Committee uses lifecycle assessment to quantify reductions, setting verification standards [34] [35] . Canada’s Quest project defines accounting boundaries, and Chinese researchers developed a storage model for Shengli Oilfield [34] - [37] . Technical standards include the EU’s Directive 85/337/EEC for capture safety, Norway’s CO₂ pipeline guidelines, and Canada’s Z-741 for saline aquifer storage [38] - [40] . These standards span the CCUS chain, supporting carbon market trading and scalability.

A robust legal and regulatory framework ensures CCUS safety, project consistency, and carbon market stability, with notable regional differences. The EU’s Directive 2009/31/EC sets storage permitting rules, enhanced by Directive (EU) 2018/2001 for full-chain oversight [41] [42] . The UK’s 2008 Energy Act and 2011 CO₂ Storage Regulations cover all storage types [43] [44] . The US regulates via the Clean Air Act, with California’s LCFS enabling market integration. Australia uses a federal-state model for balanced regulation [45] [46] . These frameworks prioritize environmental risk management, market compatibility, and cross-border cooperation, supporting CCUS scalability through clear accountability and risk-sharing.

Carbon Capture, Utilization, and Storage (CCUS) faces significant economic challenges due to high costs and the lack of a viable business model. CO₂ capture from low-concentration sources (e.g., coal-fired power plants, steel mills) costs 300 - 900 CNY/ton, with transportation adding 0.9 - 1.4 CNY/(ton·km) [14] [15] . CO₂-enhanced oil recovery can offset some costs, but project economics are limited by reservoir conditions, source proximity, and technological maturity, leading to long payback periods [47] . Cross-industry collaboration is hindered by unclear revenue sharing, responsibility allocation, and risk-sharing mechanisms. No mature commercial model exists. Policy support is lacking, with no targeted fiscal incentives (e.g., storage subsidies, carbon tax exemptions) and insufficient carbon market certification for CCUS emission reductions, failing to address high project risks [14] .

CCUS faces three key technical challenges. First, storage potential assessments lack precision, relying on static parameters like porosity and permeability without integrating 3D geological and dynamic flow analyses, limiting site selection for large-scale projects [16] [31] . Second, large-scale CO₂ injection risks reservoir damage from salt precipitation and clogging, as seen in the Gorgon project’s injection well failures, exposing reliability issues [15] [18] [48] . Third, long-term monitoring systems are underdeveloped, with onshore methods relying on costly seismic techniques and offshore monitoring limited by complex conditions and sensor constraints, creating economic and sustainability challenges for post-closure monitoring [32] [47] [49] [50] .

Institutional barriers impede CCUS industrialization. Current environmental and energy laws do not address CCUS-specific needs, lacking clear accountability for risks like storage leakage and standardized approval processes, increasing compliance costs [14] [47] . Carbon market integration lacks dedicated legislation, hindering revenue generation. Carbon accounting is flawed, with unclear guidelines reducing transparency and accuracy. Inaccuracies in measuring CO₂ emissions from enhanced oil recovery and ambiguous standards for equipment-related emissions lead to inflated reduction claims, undermining carbon market credibility [14] [45] .

To overcome economic barriers, a market-oriented framework combining policy, industry, and business models is needed. Policies should include cost-sharing mechanisms, tax exemptions for CO₂-enhanced oil recovery (EOR), and a multi-billion CNY CCUS fund for pipeline and storage R&D to reduce risks and boost participation [5] [18] . Industrially, million-ton CCUS clusters in regions like Ordos and Songliao should use shared capture, co-built transport, and centralized storage to cut costs. Business models can pilot carbon storage subscriptions (e.g., Shell’s “ton-carbon custody”) and dual-revenue streams from low-carbon crude certification and carbon credit trading, enabling oil companies to become carbon asset managers [14] . To address community concerns, CCUS projects should emphasize transparent communication and proactive stakeholder engagement to mitigate perceived environmental risks. Community-focused measures, such as local job creation through infrastructure development and revenue-sharing from carbon credit markets, can further enhance regional economic benefits and foster public support.

CCUS scalability requires innovation in technology and monitoring. A new evaluation system integrating static geological parameters (porosity, permeability) with dynamic flow responses should improve site selection accuracy [20] . Storage engineering must optimize well layouts, injection pressures, and capacities to prevent reservoir damage. Monitoring upgrades need high-precision, real-time tools like fiber-optic systems and geophysical devices, tailored to terrestrial and offshore conditions, with 3D networks for leak detection and cost-efficient lifecycle monitoring [32] . Disruptive technologies like CO₂ mineralization and bioconversion should be explored for long-term storage safety.

A robust legal and standards framework is essential. A Carbon Storage Management Law should clarify subsurface rights, saline aquifer access, and project approvals, with clear responsibilities and lifelong liability for leaks. Standards must address capture energy limits, transport specifications, and storage integrity [5] . Refined carbon accounting should standardize EOR emissions calibration and equipment emission deductions for global carbon market compatibility. Legal and technical synergy can resolve environmental risks, market integration, and international cooperation barriers, supporting CCUS industrialization.