Washington, D.C. —Field testing the potential for combining geologic carbon dioxide (CO2) storage with enhanced methane recovery is underway at a site in Alabama by a U.S. Department of Energy (DOE) team of regional partners.
Members of the Southeast Regional Carbon Sequestration Partnership (SECARB) are injecting CO2 into a coalbed methane well in Tuscaloosa County to assess the capability of mature coalbed methane reservoirs to receive and adsorb significant volumes of carbon dioxide (CO2). Southern Company, El Paso Exploration & Production, the Geological Survey of Alabama, and the University of Alabama are all participating in the field test, known as the Black Warrior CO2 Storage Project.
As part of carbon capture and storage (CCS) technology, geologic CO2 storage is considered by experts to be an important option – along with greater use of renewable and nuclear energy and enhanced efficiency – in a "portfolio" approach to reducing greenhouse gas emissions and helping mitigate climate change. The Black Warrior project will help determine the feasibility of combining carbon storage and enhanced recovery of coalbed methane, a primary component of natural gas.
CO2 Storage in Black Warrior Basin
The SECARB members began injecting CO2 at the Alabama test site on June 15, 2010. Earlier, an existing coalbed methane well operated by El Paso Exploration & Production had been converted for CO2 injection, and four wells drilled to monitor reservoir pressure, gas composition, water quality, and the CO2 plume. The targeted coal seams are in the Pratt, Mary Lee, and Black Creek Coal groups within the upper Pottsville Formation and range from 940 to 1,800 feet in depth and from 1 to 6 feet in thickness. Two hundred and forty tons of CO2 will be injected over a 45- to 60-day period.
The site was selected because it is representative of the Black Warrior Basin, an area of about 23,000 square miles located in northwestern Alabama and northeastern Mississippi. Coal in the Black Warrior Basin has the potential to sequester 1.1 gigatons to 2.3 gigatons of CO2—approximately the amount that Alabama’s coal-fired power plants emit in two decades. Enhanced coalbed methane recovery combined with CO2 storage could squeeze another 1.5 trillion cubic feet of natural gas from these coal seams.
Surface and Subsurface CO2 Monitoring
During and following injection, the project will monitor the injected CO2 at the surface and in the subsurface to ensure that storage is safe and permanent. Three deep subsurface monitoring wells will use pressure transducers and fluid sampling tubes to monitor the coal groups. While CO2 is injected into one coal seam, the others should display a minimal pressure response if the CO2 remains in the original coalbed. Pressures will also be monitored inside the well to ensure that there are no leaks. Shallow groundwater and soil gas monitoring will provide important information that can be used to evaluate the environmental safety of carbon sequestration and enhanced coalbed methane recovery operations in the Black Warrior Basin.
DOE’s Regional Carbon Sequestration Partnership Program
DOE’s Regional Carbon Sequestration Partnership program was created in 2003 to determine which of numerous carbon storage approaches are best suited for different regions of the country. The partnerships include more than 350 organizations, spanning 43 states, and four Canadian provinces.
The partnership program is being implemented in three phases. The characterization phase (2003–2005), which defined opportunities for carbon capture and storage, has been completed. The validation phase (2005–2010) generally involves small-scale field tests and includes the Black Warrior Basin CO2 Storage Project. The final phase, the development phase (2007–2018), will conduct large-volume carbon storage tests. The National Energy Technology Laboratory manages the partnership program for DOE’s Office of Fossil Energy.
SECARB is led by the Southern States Energy Board and represents more than 100 partners and stakeholders in 13 southeastern states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia, and West Virginia. SECARB is conducting four tests under the validation phase of the partnerships program and two large-volume carbon storage tests, including one in the Cranfield Oilfield in Mississippi in which more than 1 million tons of CO2 have been injected to date in the saline portion of the reservoir—one of only five projects worldwide to have reached this milestone.