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Produced Water | Session IV - Nick Tew
This document summarizes characteristics of coalbed methane produced water in Alabama. It notes that over 1.7 billion barrels of water have been produced from nearly 5,000 active coalbed methane wells in Alabama. The water is typically brackish and high in sodium and chloride. While in-stream disposal is most common, there is potential to beneficially use the water for aquaculture, irrigation, drilling, or municipal supply with additional treatment.
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Produced Water | Session IV - Nick Tew
- 1. Characteristics of Coalbed MethaneProduced Water in Alabama Nick Tew Alabama State Geologist/Oil and Gas Board Supervisor Geological Survey of Alabama State Oil and Gas Board of Alabama Atlantic Council Fossil Fuel Produced Water Workshop Washington, DC June 24-25, 2013
- 2. Alabama’s Fossil FuelEnergy Endowment Coal Black Warrior Basin Coal Measures Coastal Plain Lignite (low-rank coal) Oil Conventional SW Alabama Oil and Condensate Black Warrior Basin Oil Unconventional Oil Sands of North Alabama Oil Shale of North Alabama Natural Gas Conventional SW Alabama Black Warrior Basin Unconventional Coalbed Methane of Black Warrior Basin Paleozoic Gas Shales of North Alabama Geology of Alabama
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- 4. Coalbed Methane inAlabama • Degasification experiments for mine safety began in the mid-1970s. • Commercial production began in 1980. • Currently close to 5,000 active wells in 20 fields. • Annual gas production between 105 and 121 Bcf for the last 20 years. • More than 2.1 Tcf cumulative gas production. • More than 1.7 billion barrels of water produced.
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- 6. Cumulative Gas Production from1980-2009 Cumulative Water Production from 1980-2009 Cumulative Gas and Water Production
- 7. Development and Production •Drilling and hydraulic fracturing currently uses “city” water • Usually trucked to location • Additional water during production is not needed
- 8. Co-Produced Water • CBMproduction is pressure driven and usually requires dewatering of coals to lower hydrostatic pressure for gas production. • Water production is generally high early in a well’s life and decreases rapidly. • Gas production generally peaks in the first few years, after peak water, then decreases. • High water production can limit how often and how much a well can be pumped, limiting gas production.
- 9. Peak Gas andWater Production
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- 11. 0 500 1000 1500 2000 2500 3000 3500 0 2000 4000 6000 8000 10000 12000 14000 10/1991 10/1992 10/1993 10/1994 10/1995 10/1996 10/1997 10/1998 10/1999 10/2000 10/2001 10/2002 10/2003 10/2004 10/2005 10/2006 10/2007 10/2008 WaterProduction(bbl) GasProduction(mcf) USX 34-16-48 (OGB PN10892-C) Monthly Production Gas Water
- 12. Co-Produced Water • Asnew areas of production come on line, water production is relatively high. • As an area reaches maturity, the water production will slow and level off. • Some areas, with high recharge rates, will continue to produce significant water volumes over the life of the well. • In and around mining, where water levels have been drawn down prior to drilling, wells produce little to no water.
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- 15. Water Treatment andDisposal • In-stream disposal is the dominant practice in the Black Warrior Basin. • Prior to disposal, water is treated to remove silt, clay, iron, and manganese compounds. • Underground injection can augment in-stream disposal in areas of highly saline water; however, currently all produced water is disposed of in-stream. • Potential beneficial uses exist for produced water with less than 3,000 mg/L TDS. • In the southwestern CBM fields, water is more saline and limits the ability to pump wells.
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- 17. Water Chemistry Majorconstituents: Mostly sodium-chloride, some areas are dominated by sodium bicarbonate waters. Generally low in sulfate, magnesium, and calcium. Almost all wells exceed secondary drinking water standards for TDS (500 mg/L), but the average well is in a USDW (<10,000 mg/L). Average levels of barium, cadmium, fluoride, lead, and thallium exceeds the drinking water MCL; average levels of zinc and manganese exceed the secondary drinking water regulations.
- 19. CBM Produced Waterin Alabama Potential Beneficial Uses: Aquaculture and irrigation water, in particular shrimp farming Water for drilling and hydraulic fracturing Municipal supply Alternative water treatment: Reverse osmosis systems Artificial wetlands (Clemson-Chevron research) Alternative to in-stream disposal: SWD wells, however, no consistent high capacity zones identified
- 20. Acknowledgments GSA CBMProduced Water Project funded by the U.S. Dept. of Energy, Office of Fossil Energy, NETL, DOE Award Number DE-FE0000888. GSA Research Team: Marcella McIntyre- Redden, Steve Mann, Jack Pashin (now at OK State), David Kopaska-Merkel, Ashley Williams, and Mac McKinney.
Editor's Notes
- #6 Lower-right map’s location is roughly indicated by the blue dashed box in the upper map.
- #7 Total cumulative gas (Mmcf) and water (bbl) production. Gives sense of scale of the resource and the water disposal issue.
- #10 Peak gas (mcf/month)and water (bbl/month) production. Peak production is typically within the first few years of a well’s life. Robinson’s Bend and parts of Cedar Cove have high water production and variable gas production. Blue Creek, Deerlick Creek, and White Oak Creek fields have lower water production and generally good gas production.
- #11 Typical decline curve
- #12 Typical decline curve
- #14 Yearly water production – Illustrates the general pattern of lower water production in a well/area over time. Note, Brookwood field is mostly wells in and immediately around the mines where extensive de-watering had already occurred.
- #17 Processed produced water discharge points. Almost all discharge into the Black Warrior River or one of its tributaries.
- #19 TDS map, metals trend with TDS.