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) to provide a basis for the development of efficient regulatory guidance by quantifying the environmental impacts of CBM produced waters and potentially optimize production operations and regulatory frameworks. Such regulatory guidance will provide environmental protection while simultaneously ensuring CBM delivery to the marketplace.
Geological Survey of Alabama, Tuscaloosa, AL, 35486-6999
Black Warrior Methane
Coalbed Methane Association of Alabama
El Paso Exploration and Production
HighMount Exploration and Production
U.S. Geological Survey
Produced water management is a subject of increasing environmental scrutiny. Produced water is a valuable commodity usable over 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. These issues need to be critically analyzed and addressed so that full CBM recovery potential can be realized.
The Black Warrior Basin has a long and rich history of CBM development. The wealth of data and the geologic 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 the Black Warior Basin reservoir geology and basin hydrology. Study results should permit development of new water management strategies that will ensure environmental protection, foster beneficial use of produced waters, and improve reservoir performance.
Eighty-six water samples were collected; geochemical analysis has been completed for 25 samples. Additionally, 25 gas samples were collected. Collection of these samples complete the sampling phase of the project. Analysis of these samples will enable further characterization of the relationship between water chemistry and geologic framework, as well as aid in the development of water management strategies.
Reservoir performance has been analyzed through decline curves and production mapping. Numerous types of production decline curves were identified and some have been found to be characteristic of specific producing areas. Areas where erratic production—due to frequent well maintenance or water management issues—is common have been identified and are indicative of inefficient gas recovery. These areas will be further investigated in order to develop water management strategies.
Discharge points where processed water is released into the Black Warrior River have been identified and incorporated into a geographic information system. Mapping of these locations aids in the development of water management strategies.
Researchers characterized the petrology of the Upper Pottsville sandstones, shales, and coals. Results of authigenic cement analyses indicate that sandstone composition has had no tangible impact on authigenesis. Stable isotopic analysis of the calcite cement that lines the natural factures (cleats and joints) indicates cementation began locally early in the unroofing process in formation water with marine affinity; however, most of the cementation took place at or near modern burial depth and was associated with late-stage bacterial methanogenesis.
A manuscript has been submitted for inclusion in a special volume of the International Journal of Coal Geology. Additionally, a manuscript, entitled “Dynamics of Thermogenic and Late-Stage Biogenic Gas Generation in Coalbed Methane Reservoirs of the Black Warrior Basin,” is being prepared for the Unconventional Resources Technology Conference to be held in Denver in August 2013.
Surface geology of the Black Warrior Basin
All research has been completed and the final report is available below under "Additional Information".
Final Project Report [PDF-4.29MB] January, 2014
Research Performance Progress Report [PDF-1.58MB] April - June 2013
Research Performance Progress Report [PDF-1.58MB] January - March 2013
Research Performance Progress Report [PDF-2.74MB] October - December 2012
For a listing of project publications please visit the project website athttp://www.gsa.state.al.us/gsa/cbm/Coalbed%20Methane%20Research.htm [external site].