Carbon capture and storage

Digitalization Supports Expansion of CCS Efforts

Understanding the subsurface is crucial to the success of carbon capture and storage, and digital solutions are essential for an accurate analysis of the subsurface being considered.

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Source: Garry Killian/Getty Images

As oil and gas companies seek to lower the carbon footprint of their operations, carbon capture and storage (CCS) holds a great deal of promise. With CCS, carbon dioxide (CO2) emissions are captured, transported to CO2 storage sites, and injected into geological formations deep underground where they remain for the foreseeable future (Fig. 1). Decommissioned wells can be used as injection sites, which is especially attractive for oil and gas companies.

Fig. 1—CCS options.
Source: International Association of Oil and Gas Producers

Successful CCS implementations depend on several factors, including the availability and cost of capture technologies, the distance between source and injection sites, the geological environment, the funding model, and the regulatory and policy environment. Data and efficient data management underpin these factors and are critical to a CCS initiative’s success. Within these foundational pillars, site characterization, monitoring, and optimization and tax credits are pivotal considerations that influence how a CCS program takes shape.

Site Characterization Dictates Capacity
The proper use of data in site characterization ensures an accurate assessment of the subsurface’s capacity for CO2 injection and is necessary to determine financial investment requirements. Site characterization efforts focus on collecting and analyzing data to gather details about the subsurface geology, pore pressure profile, and geomechanical stress system.

Data availability, vintage, and quality are essential to determine a site’s suitability for CCS, whether those sites are active hydrocarbon reservoirs or deeper saline aquifers. New data, while costly, must supplement any missing information to prove subsurface viability for CO2 injection.

Ikon Science’s work with the British Geological Survey (BGS) as part of the REX-CO2 consortium to evaluate the potential reuse of wells for CO2 injection in the UK Continental Shelf demonstrates the importance of site characterization in CCS projects. The well reuse investigation focused on the saline aquifer of Bunter Closure 36 in the Southern North Sea Basin and the Hamilton depleted gas field in the East Irish Sea Basin. Bunter Closure 36 is a large dome-like structure that was targeted by an exploration well in the 1960s; however, the reservoir was abandoned. In the 1980s, an exploration well was drilled through Bunter Closure 36, this time targeting a reservoir in the much deeper Carboniferous coal measures. This later well led to the discovery of the Schooner gas field, and, during the decades that followed, numerous production wells were drilled through Bunter Closure 36 to produce gas from this deeper target. As a result, a high number of well penetrations passed through Bunter Closure 36 and will be subject to decommissioning in the coming years.

Ikon used the software program RokDoc to analyze a selection of regional wells as well as those that drilled through Bunter Closure 36 to evaluate the subsurface and verify the suitability of those wells for both reuse and CO2 injection and storage (Fig. 2). As the wells in the immediate vicinity of the Bunter Closure 36 case study lacked comprehensive pressure data measurements such as those from a repeat formation tester and modular formation dynamics tester because of the targeting of deeper Carboniferous reservoirs, Ikon’s Southern North Sea Well Database was used to examine regional wells within the same reservoir and fault block to fill in missing data.

Fig. 2—Pressure data from wells around Bunter Closure 36 in the Silver Pit Basin area of the southern North Sea.
Source: Ikon Science

This regional study enabled the team to determine that the depletion effects from producing fields, such as the Esmond gas field, were minimal (Fig. 3) and that present-day pressure was likely to be nearly hydrostatic, or potentially overpressured to around 200 psi. The data showed the reservoir was connected and demonstrated good porosity and permeability over a long distance. The results of these initial investigations on two key parameters that indicate the geological suitability of the field for CO2 injection—reservoir pressure and seal fracture strength—allowed Ikon and BGS to calculate and confirm the presence of sufficient vertical effective stress within the reservoir for safe CO2 containment. Without data and efficient data management, these vital site characterization determinations wouldn’t have been possible.

Fig. 3a—Pressure/depth plot from the first well drilled in Bunter Closure 36; 44/26-1. The figure shows pore pressure and fracture gradient estimate logs. Fracture pressure log estimates are compared to formation integrity test (FIT) and minifrac test values, at their original depths, from the 42/26-d3 well, which tested the Rot Halite (FIT), Rot Shale (minifrac), and Bunter sandstone (minifrac); the formation name is next to each test. The dashed red lines point to the equivalent formation in 44/26-1 (i.e., shallower) and provides quality control for the effectiveness of the fracture pressure estimates. The Rot Shale and Bunter sandstone fracture closure pressure (FCP) measurements show a higher fracture pressure than predicted. The salt FIT is lower than estimated by the log, but the nature of the test is to measure below fracture pressure, so the widely applied fracture pressure assumption in salt (that fracture pressure equals vertical stress) is still valid.
Source: Ikon Science
Fig. 3b—Overpressure data shown in the previous figure is displayed on a map with surrounding faults shown in red (values displayed are in psi).
Source: Ikon Science

Monitoring CO2 Containment
CCS projects require a measurement, monitoring, and verification (MMV) plan to monitor sequestration operations. An MMV tracks the migration of CO2 in the subsurface, leaks, and overburden integrity. An MMV also measures the volume of CO2 injected and verifies it stays in place.

To achieve long-term operational efficiencies, it is a best practice to combine data with a data management platform. Given that CCS projects have monitoring timelines that span more than 100 years, a centralized and efficient data retrieval platform that also enables real-time data analysis allows any integrity issues to be identified quickly for immediate mitigation. Such a tool influences the methods used to track CO2 movement, which can include pressure and temperature sensors, rock physics modeling, timelapse seismic acquisition, passive seismic, fluid sampling, and other geophysical techniques.

A modern cloud-enabled data management solution, such as Ikon’s Curate platform, enables disparate data from multiple apps to flow into it so teams can access it instantly and use work flows to uncover new learnings (Fig. 4). In a CCS project, such a platform streamlines leak monitoring and storage reporting requirements to facilitate tracking against environmental, social, and governance (ESG) and performance targets.

Fig. 4—Modern online data management systems offer simple map-based interfaces, allowing users to identify, validate, and retrieve data quickly. Top left: A map view of data against culture data showing hydrocarbon fields and accumulations. Top right: A well view on the fly with log analysis applications available. Bottom left: A multiwell log view and map view. Bottom right: A seismic viewer validates data before export. All views shown are in a single access point.
Source: Ikon Science

Optimization Supports Decarbonization Efforts
Data and data feedback loops are essential to optimize capture systems, injection strategy, and the CO2 containment program. The performance of different systems and techniques can be enhanced by continuous data gathering that informs vital aspects of a CCS project. For example, 4D seismic data that images plume migration over time in the subsurface can be used to determine new monitoring and injection well locations in the same way it is used in oil and gas field development.

Traditional oil and gas exploration laid the critical foundation for CCS initiatives, providing the seismic and well data that is required to assess the distribution and variability of geological rock properties. The ability to conduct geological characterization to optimize CCS operations stems from decades of this historic data. Legacy oil and gas subsurface data, from petrophysics to reservoir characterization, can be used to update operational plans as CCS projects evolve.

Additionally, greater understanding of lithofacies distribution and flow units can be achieved by leveraging 3D volumes of geological rock properties and forward-modeled logs. These high-resolution data products can be further used as inputs to a reservoir modeling work flow to estimate injection capacity and in-situ stresses of the formations and caprocks.

Tax Credits Incentivize CCS Projects
Tax credit programs have the potential to spur CCS project growth and allow such efforts to become more mainstream. Data and data management are necessary to collect and report the information required to qualify for available tax credits. These reported metrics include the amount of CO2 captured, the volume of CO2 injected, and verification of containment. Data architectures that allow independent authentication assure government bodies CCS projects are performing as expected and complying with local regulations. The ability to validate CCS monitoring results supports financial investment in such decarbonization efforts.

Reliable and trustworthy data platforms that store and manage the data used for regulatory reporting are crucial as well. Such platforms can be instrumental to make the regulatory reporting process more efficient, saving time and reducing associated costs for data retrieval. When you consider that Canada, for example, has tax credit rates of 60% for investment in equipment to capture CO2 in direct air capture projects and 50% for investment in equipment to capture CO2 in all other carbon capture, use, and storage (CCUS) projects, the importance of data and data management—and the easy retrieval of that data for reporting purposes—is clear. Managing rich data, derived knowledge and subsurface reservoir models within a single searchable and accessible workspace enables companies to demonstrate quickly and cost-effectively that tax credit thresholds are met.

Digitalization Enables Decarbonization
The global push to reduce emissions will increase the number of CCS projects in the coming years. The accessibility of rich data and how that data is managed can affect the viability of CCS initiatives as those foundational elements directly affect the ability to perform accurate site characterization, monitoring, and optimization to attain tax credits. Companies that establish CCS ventures on innovative open architecture data technologies that ensure data quality and data management efficiency will be poised to succeed and profit in decarbonization efforts.