DE-FE0000888

Goal
The primary goal of this project is to analyze and develop strategies for water resource management within the coalbed methane (CBM) reservoirs of the Black Warrior Basin. The objective is to develop a large, high-quality database and geographic information system (GIS), which will provide a basis for the development of efficient regulatory guidance by quantifying the environmental impacts of CBM produced waters and, potentially, by optimizing production operations and regulatory frameworks. Such regulatory guidance will provide environmental protection while simultaneously ensuring CBM delivery to the marketplace.

Performer
Geological Survey of Alabama, Tuscaloosa, AL, 35486-6999

Collaborators
Black Warrior Methane
Coalbed Methane Association of Alabama
El Paso Exploration and Production
Energen Resources
Geomet
HighMount Exploration and Production
U.S. Geological Survey

Background
Management of produced water is a subject of increasing environmental scrutiny and produced water is a potentially valuable commodity that can be used in a broad range of municipal, industrial, and agricultural applications. Some applications, such as using produced water for hydraulic fracturing, can increase efficiency while simultaneously reducing the costs of basic CBM operations. Use of produced water outside the CBM industry adds value to CBM production operations by facilitating industry, enhancing agriculture, and providing vital public services to communities affected by distressed water supplies. The CBM resource base in the Black Warrior Basin is estimated to be between 10 and 20 trillion cubic feet (Tcf). Cumulative CBM production stands at 2.1 Tcf and the most recent USGS assessment indicates that an additional 4.6 to 6.9 Tcf may be recoverable. Water management issues affect all CBM producers in the Black Warrior Basin. They need to be critically analyzed and addressed so that full CBM recovery potential can be realized.

Impact
The Black Warrior Basin has a long and rich history of CBM development. The wealth of data and the geological diversity of the basin provide an unparalleled opportunity to evaluate water management strategies across a spectrum of reservoir conditions. Accordingly, this study will help natural gas producers develop basic geologic, hydrologic, and water management concepts that can be applied to CBM plays throughout the world. The study will apply a spectrum of geologic, hydrologic, geochemical, petrologic, GIS, and other computational techniques to characterize both the reservoir geology and basin hydrology of the Black Warrior Basin. This should permit development of new water management strategies that will ensure environmental protection, foster beneficial use of produced waters, and improve reservoir performance.

Accomplishments
A presentation entitled, “Four Decades of Coalbed Methane Development in the Black Warrior Basin” was delivered at the SPE Applied Technology Workshop in West Bengal, India in September 2011.

The USGS completed analysis of organic compounds from samples collected to date. The data will provide the basis for a journal manuscript on dissolved organics, bacterial methanogenesis, and potential health issues associated with the utilization of produced water.

Geochemical analysis has been completed on 47 water samples that were obtained earlier in 2011. The concentration of nearly all major nonmetallic and metallic constituents correlates positively with TDS content.

Twenty-four gas samples were analyzed for bulk composition and stable isotopic composition. Stable isotopic data indicate mixing of biogenic and thermogenic gas. Carbon isotopes show a strong relationship to the thermal maturity of the host coal.

Databases on peak, cumulative, and annual gas production are now complete. Databases on well completions have also been compiled.

Reservoir pressure analysis was completed on schedule.

Reservoir pressure data indicate that the hydrologic system within the coal-bearing section is strongly stratified and compartmentalized, with underpressure being most widespread in the Mary Lee coal zone. Isotopic data from coalbed gases further indicate mixing of thermogenic and late-stage biogenic methane. Isotopic composition is strongly related to coal rank, and as rank decreases, produced gases become strongly depleted in 13C1. Isotopic analysis of calcite cement in joint and cleat systems shows a strong linkage with water chemistry, gas chemistry, and reservoir temperature and confirms that coal seams were the main sites of late-stage bacterial methanogenesis.

Efforts were directed toward characterizing coalbed methane reservoirs and deeper strata that can be used for subsurface disposal of produced water. Accomplishments include completion of database design, compilation and interpretation of basic subsurface data, and the construction of numerous maps and cross sections. Additional efforts included compilation of geochemical data, water sampling, geochemical analysis, and characterization of reservoir pressure and temperature. A Memorandum of Understanding with the USGS has been signed that facilitates analysis of dissolved organics and radiometric dating of formation waters.

Project work commenced in October 2009. A project management plan was developed and a technology status assessment was completed. A project web site has been posted at the following URL: http://www.gsa.state.al.us/gsa/cbm/Coalbed%20Methane%20Research.htm [external site].

Surface geology of the Black Warrior Basin

Current Status (October 2011)
Research efforts have been greatly curtailed due to the lack of funding for FY11. To accommodate the possibility of future funding, the project was granted a no-cost time extension. Should funding become available, priority will be given to collecting water and gas samples from the southwestern coalbed methane fields, where water and gas chemistry may differ substantially from that in the areas already sampled.

Project Start: October 1, 2009
Project End: September 30, 2012

DOE Contribution: $725,647
Performer Contribution: $ 314,316

Contact Information:
NETL –Skip Pratt (skip.pratt@netl.doe.gov or 304-285-4396)
GSA – Jack Pashin (jpashin@gsa.state.al.us or 205-247-3558)
If you are unable to reach the above personnel, please contact the content manager.

Publications

For a listing of project publications please visit the project website at http://www.gsa.state.al.us/gsa/cbm/Coalbed%20Methane%20Research.htm [external site].

OGIP for the Black Warrior Basin