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Abstract
The Plains CO2 Reduction Partnership is working with Denbury Resources to evaluate the efficiency of large-scale injection of carbon dioxide (CO2) into the Bell Creek oil field for simultaneous CO2 enhanced oil recovery (EOR) and long-term CO2 storage. Discovered in 1967, the Bell Creek Field in southeastern Montana has produced approximately 133 million barrels (MMbbl) of oil from the Cretaceous Muddy Formation sandstone. The original oil in place (OOIP) for the field was estimated to be approximately 353 MMbbl of oil. Through primary and secondary production, about 37.7% of the OOIP has been produced, leaving an estimated 220 MMbbl of oil in the reservoir. It is estimated that CO2 flooding will produce an additional 35 MMbbl of incremental oil, while simultaneously storing large volumes of CO2 in the deep subsurface.

Approximately 50 million cubic feet of CO2 a day will be captured at the ConocoPhillips Lost Cabin gas-processing plant in central Wyoming and transported via a 232-mile pipeline to the Bell Creek Field. Plans are under way to build compression facilities adjacent to the Lost Cabin gas plant to compress the CO2 from 50 to 2200 psi, allowing for injection-ready pressures at the project site. The CO2 will then be injected through multiple injection wells into the Muddy Formation at a depth of approximately 4500 feet.

A baseline CO2-monitoring program is currently under development to establish preinjection CO2 concentrations at the surface and in the shallow subsurface. Additionally, pressure and fluid saturations will be measured in the reservoir to establish preinjection conditions, so that repeat measurements can be used to better quantify the amount and location of the injected CO2.

The Bell Creek integrated CO2 EOR and storage project provides a unique opportunity to develop a set of cost-effective monitoring techniques for large-scale (>1 million tons a year) storage of CO2 in a mature oil field with EOR. The results of the Bell Creek project will provide insight regarding the impact of large-scale CO2 injection on sink integrity, monitoring techniques, and regional applicability of implementing successful CO2 storage projects within the context of EOR.