Taking CO2 Enhanced Oil Recovery to the Offshore Gulf of Mexico: A Screening-Level Assessment of the Technically and Economically Recoverable Resource

Abstract

Summary This paper evaluates the recoverable crude-oil resource associated with applying carbon dioxide (CO2) enhanced oil recovery (EOR) to reservoirs in the offshore Gulf of Mexico (GOM). By use of data maintained by the Bureau of Ocean Energy Management (BOEM), a database containing 531 oil fields with total oil originally in place (OOIP) of 69 billion bbl was used for the study. A total of 391 fields, representing 35% of the OOIP, were screened out at as not amenable to CO2 EOR because of size, residual oil saturation (ROS), and/or well spacing. For the remaining 140 oil fields (containing 696 reservoirs), the data elements required to model a CO2-EOR flood, such as sweep efficiency and heterogeneity, were derived by use of a variety of methods. Crude-oil production and CO2-demand profiles were produced from streamtube finite-difference simulations for each oil-bearing reservoir. The study assumes that groups of proximate fields will be served by an anchor CO2-supply pipeline (1 billion scf/yr of CO2) at a levelized transportation cost of USD 1.06/Mscf of CO2 (equivalently USD 20/t of CO2). The economic determinations are derived from a crude-oil price of USD 90/bbl, CO2 price of USD 1.59/Mscf (USD 30/t of CO2) at the capture facility plant gate, 18.75% royalty, and a 20% rate of return before taxes. BOEM projects that 182 billion bbl of OOIP remains undiscovered, 2.5 times the discovered resource. The BOEM database of discovered fields cuts off after 2008, and a portion of the undiscovered resource, 40 billion bbl of OOIP, has since been announced as discovered. Data from the analysis of discovered oil fields were used to estimate the expected CO2 EOR from the undiscovered oil fields. Under the current CO2-EOR technology scenario, the economically recoverable resources (ERR) are 0.8 billion bbl, a small fraction of the technically recoverable resource (TRR) of 23.5 billion bbl. The average efficiency of CO2 use in the ERR oil fields is estimated to be 7.2 Mscf/bbl and the associated demand for CO2 supply is 5.8 Tcf. Under a scenario with next-generation CO2-EOR performance, the ERR increases significantly to 14.9 billion bbl and 74 Tcf of CO2 demand, consistent with an improved use efficiency of 5.0 Mscf of CO2/bbl. Thirty-five percent of the total ERR estimate is from discovered fields, whereas the remaining 65% is from undiscovered fields.