CCS: The Keys to Executing an Essential Solution to Carbon Neutrality

Carbon capture and storage (CCS) is the proven and demonstrated process of capturing CO₂ from industrial carbon emission sources and transporting it to subsurface geologic formations for permanent storage.  According to many credible energy transition studies, CCS is critical to achieving ambitious societal goals around carbon neutrality such as California’s greenhouse-gas (GHG) emissions reduction targets of 40% by 2030 and net-zero by 2045. The scale of CCS projects varies significantly, particularly between offshore and onshore storage complexes. Implementation, operation and monitoring of storage complexes associated with CCS projects at-scale requires expertise across many disciplines.

A pragmatic and informed working knowledge of subsurface complexity, land positioning, commercial models and broader stakeholder expectations is instrumental to the early and impactful adoption of CCS.

The oil and natural gas energy industry, through its unique positioning and skill set, is ideally situated to lead CCS innovation to lower carbon intensity associated with energy production across many industrial sectors while simultaneously developing the infrastructure and capability to build out the renewable and zero-emission energy complexes of the future.

To promote acceptance and action on immediately available decarbonization projects, and to capitalize on this opportunity, CCS advocacy efforts should recognize and communicate three fundamental realities underpinning successful at-scale execution of subsurface sequestration. The first reality is that near-term commercially viable storage, technical experience and capital investment are vital to bring a CCS project to market.  Second, existing and abandoned wellbores are valuable and manageable assets for monitoring CO₂ migration. And finally, broad stakeholder engagement across the entire value chain and stakeholder realm is crucial to the CCS industry launching successfully.

Required resources

Prior storage assessment efforts within the continental U.S. from reputable agencies such as the United States Geological Survey and National  Energy Technology Laboratory (NETL) indicate average storage of 3,000 gigatons and 8,613 gigatons, respectively, throughout sedimentary basins nationally.  Near-term actionable storage must meet the geologic and reservoir quality screening criteria while also meeting required minimum technical and risk thresholds to qualify as viable sites. Practically, storage sites should be located within reasonable proximity to emission sources and transportation networks for associated projects to be commercially viable.

Permitting Class VI UIC CO₂ injection is project-specific, requiring detailed stratigraphic and structural mapping, geologic modeling, plume development, migration simulation, proof of isolation of underground sources of drinking water and assessment of geologic considerations such as caprock integrity and pressurization. Considering the complexity of this effort, an experienced technical team needs to understand the criteria and identify the suitable combination of characteristics needed to progress study areas to qualified and permittable sites. Techniques such as reservoir pressure management will also be key considerations in every project of significant size.

CO₂ Storage Resource Management Systems (SRMS), analogous to the Petroleum Resources Management Systems, has been developed by SPE to assist in classification and categorization of storage reserves. The Carbon Sequestration Leadership Forum (CSLF) proposed a CO₂ storage capacity pyramid very similar to the hydrocarbon resource pyramid of technically recoverable reserves. Figure 1 shows the relationship between total capacity, storage certainty and cost of storage. Based on the requirement for high certainty of storage potential necessary to book storage, it is understandable that near-term,  actionable storage represents only a fraction of theoretical storage capacity.

As CCS adoption increases, tools such as SRMS can be used to quantify and certify the viability of storage resources in early-stage storage projects. Through demonstration during the injection phase, SRMS or other similar processes will inform the assessments of remaining and ultimate storage volumes. Ultimately, storage capacity will be defined at the project level with consistent and quantifiable definitions. Actionable storage capacity will be defined by public and regulatory acceptance and enabled by project economics and projected investor returns. Additionally, properly valuing qualified storage resources is instrumental to forming mutually beneficial partnerships across the CCS value chain to rapidly launch and advance the CCS  industry.

Value of existing wellbores

Re-purposing depleted oil and gas fields for CO₂ storage  is advantaged over nondeveloped regions by established and fully characterized geologic descriptions, known reservoir conditions,  production and injection history, and most importantly, pressure-depleted pore space. Existing wells are also ideally positioned to safely and reliably act as monitoring wells for active injection and post injection.

Regarding the integrity of well cement interaction with CO₂ and brine, a substantial body of empirical evidence developed by the NETL supports the resiliency of standard Portland cements due to the self-healing reactions of Portland cement in the presence of CO₂ and brine. Carey et al (2007) first observed field evidence of this interaction when retrieving cement samples from SACROC  wells after 30 years of active CO₂ flooding for EOR. Recently, Carey et al (2019) also presented combined empirical,  experimental and numerical studies indicating a significant reduction of previously perceived risks of leakage and uncertainty of CO₂ storage permanence. 

Subsurface experts trained in reservoir management, well design and well integrity with demonstrated safety records in oil and gas operations are best positioned to evaluate and manage well assets available for the efficiency and commerciality of the CCS industry. Current and established skillsets and assets directly translate to impactful near-term enablers to kick-start this new industry.

Early stakeholder engagement

Identifying and engaging all CCS project stakeholders early in the project development process helps build acceptance and support. Stakeholders are not only employees, investors, landowners, and partners but also include the numerous regulatory agencies that will advance CCS  projects through the permitting process. Elected officials, industry associations, local planning officials, influential business leaders, academia and local community members and leaders are instrumental in enabling project developers with track records of major project implementations, technical excellence and environmental stewardship. Partnership and accountability with the broader communities where CCS projects operate will demonstrate a long-term commitment to provide local revenue enhancement and support education and employment opportunities for local resident stakeholders.

Because CCS projects will actively inject for durations of 10 to 30 years and post-injection monitoring will continue for several years to decades after, stakeholders will favor credible, established operators that are committed to seeing these projects through responsibly and successfully.

CCS viability

The energy field of the future and the oil field of the present are more similar than different. Skill sets, expertise and experience have broad overlap. Many future renewable energy and fuel sources will require capture and sequestration of CO₂ emissions to achieve net-zero and negative emissions impacts.

As pore space is evaluated for CO₂ storage by project subsurface engineering and geoscience teams, available commercial storage capacity will continue to evolve.  Legacy and existing wellbores associated with mature and depleted oil and gas fields are an asset to CCS projects and can be managed with technology and industry expertise. The location and societal acceptance of CCS projects also hinge on the success of the CCS industry’s external engagement with all stakeholders.  Many communities currently producing oil and gas welcome these projects, understand the value of jobs and tax revenues, and are hoping to provide affordable, reliable energy and energy independence to their local communities, states and country.

About the author: Joe Jephson is a petroleum engineer and energy transition enthusiast with two decades of industry experience onshore and offshore, in operations, completions, production engineering, technology scouting and now CCS/CCUS carbon management. At California Resources, Jephson is leading well engineering efforts for Carbon TerraVault CCS geologic sequestration and supporting CO₂-EOR CCUS.