A Screening Tool for Assessing Feasibility of Re-using Existing Oil and Gas Wells for CCUS Operations

Abstract

An increasing number of oil and gas fields around the world are coming to the end of their production lifetime and have been earmarked as potential targets for deploying large-scale carbon capture, utilization and storage (CCUS) operations. Existing oil and gas fields offer several advantages such as availability of existing infrastructure including wells as well as significant prior knowledge about the field through characterization and operational data. Existing wells at these fields could potentially be used as CO2 injection wells, monitoring wells or production wells for pressure management. Re-using existing oil and gas infrastructure may be particularly crucial for offshore environments where new well development costs could otherwise be prohibitive. Prior to converting the existing oil and gas wells, feasibility of their use as part of a CO2 storage operation will have to be evaluated while taking into consideration operational and safety requirements. Currently there are no standard approaches available for assessing the potential of converting existing wells for re-use in CCUS operations, and no public tools are available to aid the assessment process.

As part of the REX-CO2 (Re-using EXisting wells for CO2 storage operations) project funded by the ACT (Accelerating CCS Technologies) program, we have developed a workflow and a well screening tool that will aid in evaluating the feasibility of repurposing existing wells as CO2 storage site wells. The workflow was informed by applicable standards such as ISO 27914, regulatory requirements such as the US-EPA’s Class VI regulation and publicly available information from projects that have performed detailed assessments of using existing oil and gas wells for CO2 storage, including the Peterhead, Kingsnorth and PORTHOS projects. Our assessment approach and the tool are designed to simultaneously save CO2 storage projects resources and time by identifying existing infrastructure that is safe to re-use, while determining which wells must be remediated to ensure safe, long-term storage. The functionality of the tool will be evaluated and validated on six case study sites, one in each of the REX-CO2 project’s partner countries (France, the Netherlands, Norway, Romania, the UK, and the USA).

Keywords: reuse, existing infrastructure, repurpose hydrocarbon wells, well integrity assessment