Carbon Capture and Storage in Depleted Oil and Gas Reservoirs

Technically Well Established and Commercially Feasible with Carbon Taxes and Cross-Border Duties

As we have looked at end of life oil & gas assets to investigate geothermal potential, it is common to find some reservoirs that are not suitable for geothermal, but are well suited for Carbon Capture and Storage purposes. Existing wells, surface facilities, and pipelines can often be repurposed for CCS as part of the Circular Economy. This is an immediate opportunity to mitigate excessive carbon emissions whilst Renewables continue to be deployed and scaled.

  • Carbon Capture technology at source (e.g., exhausts) is well established with good chemical absorption and membrane technologies;
  • Carbon Compression and Transportation in pipelines is well established;
  • Enhanced Oil Recovery (EOR) has successfully used Carbon Dioxide for increased oil recovery for many years. Injected into oil reservoirs the CO2 has increased oil recovery and the incremental oil can achieve a net carbon negative status. A large percentage of this CO2 is permanently trapped downhole demonstrating the viability of storage in depleted oil reservoirs;
  • Depleted gas fields have been successfully trialled for CO2 injection based on their proven ability to maintain a seal (containment) with high reservoir pressures, good permeability (injectivity) demonstrated during prior production, and storage volume (capacity) shown based on production;
  • Carbon dioxide has also been successfully stored in saline aquifers, but the use of depleted oil & gas reservoirs may offer the use of existing infrastructure including wells, surface facilities, and pipelines. The Circular Economy challenges us to reutilise existing infrastructure like this to further lower the carbon footprint of any new facilities. For large depleted oil & gas reservoirs, some new injection wells may be required down-dip and up-dip wells could be used for monitoring purposes (as shown in figure on the right);
  • As the use of emission free Renewable Energy sources continue to be scaled up, it is inevitable that conventional carbon based fuels will continue to be used globally for another couple of decades, but CCS offers a way to mitigate these emissions safely and effectively. Economics would be based on avoiding carbon taxes and cross-border duties and satisfying regulatory requirements.

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