Linking CO2-EOR and CO2 Storage in the Offshore Gulf of Mexico
Authors: Koperna George Jonathan , Ferguson Robert Clark 
Published: May 2011

Abstract
The Offshore Gulf of Mexico (GOM) has been endowed with a large oil resource, providing 25% of the United State's daily oil production in 2008. As the shallow water reservoirs mature and decline in productivity, deep water finds have been able to arrest production decline in the Gulf. Now that deep water development appears to have reached a plateau, it is logical to consider secondary and/or tertiary recovery methods for extending the productive lives of these fields, particularly in the numerous more mature shallow water GOM oil fields. Based on the characteristics of these reservoirs, carbon dioxide enhanced oil recovery (CO2-EOR) may hold tremendous potential for recovering what would otherwise be permanently stranded oil and for efficiently storing CO2 in the vertically stacked fault blocks typical of offshore fields. This application also presents synergistic opportunities for beneficially using and permanently storing CO2 captured from anthropogenic sources along the Gulf Coast.
This United States Department of Energy - National Energy Technology Laboratory sponsored study will subdivide the offshore resource base into Federal and State waters, highlighting the methodology employed to assess the applicability of CO2-EOR in extending the productive life of these fields. Key findings will summarize the technically recoverable resource and the ultimate CO2 utilization and storage potential using a water-alternating-gas flood design. The technically recoverable resource will then be further delineated using an economic screening model that applies various oil prices and CO2 costs to establish economic viability. Although the Offshore Gulf of Mexico is a high cost operating area, the opportunity for additional oil recovery and permanent CO2 storage make CO2-EOR a synergistic recovery option.

Introduction
Oil production from the offshore Gulf of Mexico, provides Louisiana, and to a lesser degree Texas, a significant portion of its general revenue and an important portion of its economic and employment base. However, production from shallow waters (less than 200 meters water depth) has been in decline for more than a decade (Figure 1), with crude oil production dropping from over 300 million barrels in 1997 to less than 150 million barrels in 20071. From 1997 through 2002, a marked increase in oil production from the deep federal waters (greater than 200 meters) has helped offset these declines in shallow water oil production. However, deep water oil production has reached a plateau and appears to be in decline as well. Given the increasing maturity of the shallow water oil fields, along with the relatively slow pace of development in the deep water areas, it appears unlikely that deepwater development will continue to offset the overall decline in offshore oil production.
Based on an assessment of the Bureau of Ocean Energy Management, Regulation and Enforcement's (BOEMRE) " Sands Database?? 2, the Offshore Gulf of Mexico has an estimated original oil in-place (OOIP) endowment of over 46 billion barrels, of which nearly 19 billion barrels have been either produced or classified as proved reserves (Figure 2). Should no additional enhanced recovery activities be undertaken, this could strand over 27 billion barrels of oil (59% of OOIP). Similarly, when the 150 largest oil reservoirs are tabulated (Figure 2), nearly 18 billion barrels out of an original endowment of nearly 30 billion barrels of oil (60% of OOIP) could be left behind.