CO2 storage in depleted oil fields: The worldwide potential for carbon dioxide enhanced oil recovery

Abstract

Abstract One option for storing the captured CO 2 from the deployment of CO 2 capture and storage (CCS) is to inject the CO 2 into oil fields, using it to produce additional oil. This option, called CO 2 enhanced oil recovery (CO 2 -EOR), can provide a “bridge” to a low-carbon energy future. However, to date, CO 2 -EOR has only occurred in a few regions, and just a few of these CO 2 -EOR projects have pursued CO 2 storage as a co-objective. To better understand the potential and constraints offered by integrated CO 2 -EOR and CO 2 storage, this study addressed three questions: (1) How large is the world-wide oil resource potential and associated CO 2 storage capacity offered by CO 2 -EOR, today and in the future? (2) What factors have facilitated or hindered the wide-scale deployment of CO 2 -EOR? and (3) What set of actions could significantly increase storage potential from the integrated application of CO 2 -EOR and CO 2 storage? We reviewed the major CO 2 -EOR operations underway around the world to better understand the factors that facilitated or hindered their implementation. The study concluded that CO 2 -EOR is not a new phenomena, and that commercial-scale, profitable CO 2 -EOR has been underway for over 30 years in geologically favorable oil fields with access to affordable CO 2 . The CO 2 -EOR experience in the U.S. and elsewhere shows that CO 2 -EOR is successful in oil fields that: (1) meet the technical criteria for achieving miscibility (primarily depth and oil composition); (2) have sufficient unrecovered oil after primary and secondary recovery (water flooding); (3) have access to reliable sources of CO 2 at affordable costs; (4) are being developed by operators with the technical knowledge and commercial interest in pursuing CO 2 -EOR technologies; and (5) can benefit from government incentives that promote CO 2 -EOR projects. To assess worldwide CO 2 -EOR potential, a database of the largest 54 oil basins of the world (that account for approximately 95% of the world’s estimated ultimately recoverable oil potential) was built, including representation of some of the major oil fields in these basins. From this, a high-level, first-order assessment of the CO 2 -EOR oil recovery and CO 2 storage potential in these basins was developed, using US experience as analogue. We then tested our basin-level estimates with reservoir modeling of 47 large oilfields in 6 of these basins. These basins are estimated to contain 4,622 billion barrels of original oil in place (OOIP) in discovered oil fields, within which remains an oil target of 3,090 billion barrels for CO 2 -EOR. After screening these basins for CO 2 -EOR potential and deleting those that are not technically favorable for miscible CO 2 -EOR, we estimated that 470 billion barrels could be recovered from fields favorable for miscible CO 2 -EOR, and could facilitate the storage of 140 billion metric tons (Gt) of CO 2 . These basins also contain an estimated 8,700 billion barrels of undiscovered oil in-place (as of the year 2000), with 2,900 billion barrels of this resource estimated as recoverable. If CO 2 -EOR technology could also be successfully applied to this undiscovered resource, our estimates of the potential for the world-wide application of CO 2 -EOR grow to 1,070 billion barrels of oil, with associated CO 2 storage potential of 320 Gt. Currently, approximately half of the potential CO 2 demand for CO 2 -EOR operations in discovered fields in the world can be met by large, identified anthropogenic CO 2 sources within distances of 800 kilometers, a distance comparable to existing and planned CO 2 pipelines serving EOR projects. These CO 2 supplies could support the production of 225 billion barrels of incremental oil through CO 2 -EOR operations. New anthropogenic sources, such as the large refineries and hydrogen plants being constructed in the Middle East, the development of high CO 2 content natural gas fields in the Far East, the aggregation of smaller CO 2 sources, and the construction of longer, larger capacity, pipelines could provide the bridge between CO 2 supply and demand for CO 2 -EOR. Assuming U.S. $15 per metric ton as the cost for CO 2 (to cover compression and transportation costs), the vast majority of this technical CO 2 -EOR potential could be economic to pursue at a $70/barrel world oil price.