Managing the transition of depleted oil and gas fields to CO₂ storage

Overview

This work aims to provide a careful and thorough exploration of the major issues involved in the transfer of use of a field from hydrocarbon extraction to CO₂ storage, to identify both the pros and cons of such a transition. Exploring the technical, economic, regulatory, and commercial factors that need to be navigated. Case studies are included, and recommendations are made on ways to overcome barriers and maximise opportunities.

Summary

• One of the advantages of utilising depleted fields as a CO₂ storage site includes the wealth of data and experience that have been gained in producing the field for hydrocarbons.
• Several current projects where a depleted field is being developed for CO₂ storage have continuity of the hydrocarbon production operator and subsequent storage operator, thereby transferring data and knowledge – however, in the future, this might not be the case and it will be critical to the success of a project how the data is stored and accessed.
• Re-use of infrastructure, although an attractive proposition, is highly site-specific and nuanced, and can be dependent on factors such as remaining life, timing of handover, conditions of well plugging and abandonments.
• A depleted field with low pressure places specific challenges due to the pressure and temperature differential between the incoming CO₂ and reservoir.
• Cost considerations to developing a depleted field into a CO₂ storage site include the value of recoverable hydrocarbons; maintenance of installations prior to CO₂ storage following production, legacy wells workover costs and monitoring; costs to cover lower injection rates at early stages of operation; heating the injection stream and delayed decommissioning costs.
• The transfer of assets between a hydrocarbon production operator and storage operator is poorly resolved in current regulatory frameworks, and its unclear how decommissioning costs and obligations, which are liable to the hydrocarbon asset owners, will be transferred.
• There are remaining challenges in the US in relinquishing mineral rights for CO₂ storage in current CO₂-enhanced oil recovery (CO₂-EOR) projects should oil prices make the site economic in the future.