Coalbed Methane Produced Water In The Western Us

water have any significant capacity for removal of salts or sodium.12 Studies prompted by recent CBM industry expansion have investigated, without significant field-scale success, potential uses of agricultural plants for the uptake and removal of salt—primarily sodium—from CBM produced water applied to agricultural landscapes (Bauder, 2008). However, similar to application of zeolites, no commercial-scale operations for CBM water treatment using phytoremediation are known at this time.

Research with an artificial sedge wetlands system to treat CBM produced water has investigated constituents concentrated in produced water, mainly SAR, iron, and barium, and whether these constituents could be treated cost effectively with artificial wetlands. The constructed wetlands effectively sequestered iron and possibly barium but resulted in no significant capability for reducing salinity or SAR (Schulz and Peall, 2001). Barnes et al. (2002) found that wetlands of the Mkuze Wetland System in northern KwaZulu-Natal served as a sink for significant amounts of calcium, potassium, and silicon but served a lesser role in the sequestration of magnesium and sodium. These results were consistent with a study of wetlands treatment of Powder River Basin water, reporting preferential uptake of calcium and magnesium, relative to sodium uptake by wetlands plants. As a result, SAR of shallow alluvial groundwater actually increased over time (Bauder et al., 2008).

A similar study performed at Clark County Wetlands Park, Nevada, reported that the natural wetlands filtering process did not affect salinity, dissolved oxygen, chloride concentrations, alkalinity, hardness, turbidity, or total suspended sediment. Moderate reductions to pH, sulfate, and nitrate were observed, but the reductions were considered negligible (Pollard et al., 2002). Lymbery et al. (2006) reported that Juncus kraussii (cattails), in constructed wetlands sites effectively removed nitrogen and phosphorus (plant nutrients) but had essentially no net effect on sodium removal.

Ancillary, Secondary, and "Polishing" Treatments

Although sodium and salinity are the principal constituents of CBM produced water that have received the most attention with respect to treatment, NPDES and state and tribal regulatory agency permits may require treatment for other constituents prior to discharge of CBM produced water to surface waters. These other treatments are generally either a specific requirement for disposal (i.e., filtration, chlorination, pH adjustment, bacterial and viral control) or specific to unique constituents that are found within the produced water and require treatment for a specific water use. In addition, the Safe Drinking Water Act requires EPA to protect potential underground sources of drinking water from contamination that could occur from subsurface injection. This statute has also been applied to shallow wells

12See www.netl.doe.gov/technologies/oil-gas/Petroleum/proj*ects/Environmental/Produced_Water/15166.htm or cf-pub.epa.gov/ncer_abstracts/INDEX.cfm/fuseaction/display.abstractDetail/abstract/8742/report/F (accessed February 23, 2010).

used to discharge CBM produced water through alluvial aquifer recharge and to the use of horizontal subsurface drip discharge.

Constituents that have instigated additional or ancillary treatment include fluoride, barium, ammonia, and bicarbonate (Rice and Nuccio, 2000; Wyoming DEQ, 2000; Veil, 2002).13 To date, no substantial evidence of entric bacterial or pathological contamination presence has been documented in CBM produced water.

Ancillary treatments that deserve mention include chlorination and nanofiltration of coal fines (particulate matter) prior to reverse osmosis treatment. At present, no evidence exists of substantial use of any of these treatments on a large commercial scale for the treatment of CBM produced water, either for beneficial use or disposal.

TREATMENT AND DISPOSAL COSTS

Treatment and disposal costs are variable and are a function of numerous circumstances and conditions, including the extent of treatment required, access to disposal facilities, water production volumes, water transport distances, and natural variations among basins. Variations in the price of natural gas may also play a role (see Chapter 2). Table 6.3 presents a summary of reported treatment and disposal costs for CBM produced water gathered from several sources, including reports, conference proceedings, news releases and industry fact sheets. Technologies which are not currently used at commercial scale have not been included in the table. Another factor affecting costs for treating CBM produced water is that produced water volumes will diminish through time (see also Chapter 2), with the implicit concern that the delivered water volume will not remain constant.

For the CBM producer, the most influential factor in CBM produced water management decision making is the cost for treatment plus associated infrastructure, which may include costs to gather, transport, deliver, treat, and/or discharge the produced water. Because of these variables, the committee was unable to find either complete or precise cost estimates to quantify water management costs more precisely than those presented in the table. The EPA study (Box 3.2) originally intended to survey CBM operators' produced water treatment practices and costs, as a basis for assessment of whether technology-based treatment and effluent limitation guidelines should be applied to CBM produced water. The RPSEA study is now compiling this kind of information and is working in partnership with EPA and other groups.

Ancillary costs may include the cost of transportation, pipelines, irrigation systems and management per unit area of land irrigated plus the cost of crop management, harvesting, storage and transportation. Regulatory requirements regarding how the produced water may be used (see also Chapters 3 and 4) further constrain the type of treatment facility

13See also www.patentstorm.us/patents/7081204/description.html (accessed February 23, 2010).

COALBED METHANE PRODUCED WATER IN THE WESTERN U.S

TABLE 6.3 Summary of Reported Produced Water Treatment and Disposal Costs

Disposal or Unit Cost/ Capital Equipment Cost or

Treatment Method Barrel Access Fee Reference

TABLE 6.3 Summary of Reported Produced Water Treatment and Disposal Costs

S0.75-S4.00 S3.00-S5.00

$400,000 to $3 million

Veil et al. (2004); ALL Consulting (2003)

Huang and Natrajan (2006) Hightower (2003)

Fluid-bed resin exchange— Drake Water Technologies

S0.12-S0.30

$325,000

See www.pttc.org/newsletter/ 3qtr2008/v14n3p12.htm (accessed February 23, 2010)

Fixed-bed resin exchange— Exterran EMIT Technology

S0.15-S0.60

See www.pttc.org/newsletter/ 3qtr2008/v14n3p12.htm (accessed February 23, 2010)

Subsurface drip irrigation

S0.16-S0.24

$6,000/acrea

J. Zupancic, BeneTerra, Inc., LLC, personal communication, December 22, 2009

Freeze-Thaw Evaporation

S0.24-S0.32fc; S0.75-S1.00

$1.75 million to $2 million

ALL Consulting (2003); J. Boysen, BC Technologies, Inc., presentation to the committee, March 30, 2009

Reverse osmosis

S<0.01-S0.10= S0.01-S0.03

$200,000 to over $2 million

ALL Consulting (2003) Stewart and Takichi (2007)

Land-applied using soil amendments

S0.06-S0.45

Cost of water-spreading infrastructu re/i rrigation equipment; $3,000-$5,000 per acre-foot

Huang and Natrajan (2006); Zhao et al. (2009)

aPer-unit costs and capital equipment costs are mutually exclusive (i.e., one or the other). fcThese two costs refer to the freeze-thaw operation and disposal of the concentrated effluent. Costs include other treatment techniques and waste stream is deep-well reinjected. NOTE: The presentation of costs above does not take into account specific flow rates of CBM produced water from a typical well. Otton (2006) indicate that the range of flow for CBM wells is from 1 2-234 barrels per day per well (0.35-6 gpm) depending on CBM basin. A bathroom faucet in a home at 80 pounds per square inch gauge turned on most of the way will be close to the lower range and a water hose opened all the way is approximately the upper range. These are very small flows for wellhead treatment systems. Treatment equipment for these sizes is similar to point of entry, point of use, fish ponds, or swimming pool applications. Vendors for this size equipment are vastly different than for centralized systems with flows from 100 to 200 times greater. Only when a number of CBM produced water wells can be centralized would economies of scale be achieved for the water treatment vendor and the well operator with regard to treatment costs. However, the capital for the collection and transport of the untreated water from the well head to a centralized system may be higher that the capital for the treatment equipment.

that may be employed. Certain treatment technologies are optimized for large, long-term, and constant-water flow-throughs, which cannot be assured in the case of CBM produced water treatment. The single most-significant cost associated with treatment for discharge is disposal of waste brine. The second most-significant cost associated with treatment for discharge in the Powder River Basin is transportation associated with brine hauling and disposal.14

CHAPTER SUMMARY

Currently available water treatment technologies allow almost any water quality requirement or goal to be achieved, regardless of the initial quality or quantity of the source water. Mitigating factors such as costs, uncertainty about quantities and duration of water supply, water transport and storage, and the legal framework for application of produced water to beneficial uses place practical constraints on the flexibility to use these technologies to achieve a desired water quality for a specific purpose.

Treatment technologies with extensive performance histories have been demonstrated as effective and have been implemented on a commercial scale to achieve any regulatory discharge permitting requirements for CBM produced water, particularly in the Powder River Basin. Regulatory agency permitting requirements vary specifically with each permit. In nearly 100 percent of the cases where CBM produced water is being treated, the degree of treatment of CBM produced water is driven by regulatory requirements for disposal, permitted discharge, or waste management. In few instances is CBM produced water being treated for the primary or specified purpose of achieving quality for beneficial use.

Within the Powder River Basin, approximately 15 to 18 percent of the produced water is being treated to reduce sodium and salinity levels to meet NPDES-permitted SAR and EC discharge requirements. The predominant treatment (90 to 95 percent) is ion exchange for reduction of sodium and bicarbonate concentrations. Within most other basins, the predominant water management strategy is disposal by deep-well reinjection.

Capital construction costs and per-unit water treatment costs vary across information sources and treatment technologies. Per-unit treatment costs are set by a separate "treatment" industry and are a reflection of research and development costs, operation costs, and input and outflow water qualities and quantity. The single most significant cost associated with treatment for discharge is disposal of waste brine. The second most significant cost associated with treatment for discharge in the Powder River Basin is transportation associated with brine hauling and disposal. Even where CBM produced water is intentionally put to beneficial use, the cost of implementation of such use (e.g., the cost of transportation,

14D. Brown, BP America, presentation to the committee, June 2, 2009; also T. Olson and D. Beagle, Exterran Water Management Services, personal communication, August 4, 2009.

COALBED METHANE PRODUCED WATER IN THE WESTERN U.S

pipelines, irrigation systems, and management per unit area of land irrigated plus the cost of crop management, harvesting, storage, and transportation versus the value of the commodity produced) in a limited local market may exceed any realized economic gain.

REFERENCES

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ALL Consulting. 2005. Technical Summary of Oil & Gas Produced Water Treatment Technologies. Prepared for the National Energy Technology Laboratory, U.S. Department of Energy. J.D. Arthur, B.G. Langhus, and C. Patel, eds. Tulsa, OK: ALL Consulting.

Barnes, K., W. Ellery, and A. Kindness. 2002. A preliminary analysis of water chemistry of the Mkuze Wetland System, KwaZulu-Natal: A mass balance approach. Water S.A. 28(1):1-12.

Bauder, J.W. 2008. Evaluation of Phytoremediation of Coal Bed Methane Produced Water and Waters of Quality Similar to that Associated with Coal Bed Methane Reserves of the Powder River Basin, Montana and Wyoming. DOE Award No. DE-FG26-01BC15166. Prepared for National Energy Technology Laboratory, U.S. Department of Energy. Available at http://www.netl.doe.gov/technologies/oil-gas/Petroleum/projects/Environmental/Produced_Water/15166.htm (accessed August 31, 2010).

Bauder, J.W., L.S. Browning, S.D. Phelps, and A.D. Kirkpatrick. 2008. Biomass production, forage quality, and cation uptake of Quail Bush, Four-Wing Saltbush, and Seaside Barley irrigated with moderatey saline-sodic water. Communications in Soil Science and Plant Analysis 39(13-14):2009-2031.

Bergsrud, F., B. Seelig, and R. Derickson. 1992. Treatment Systems for Household Water Supplies: Reverse Osmosis. Fargo: North Dakota State University Agriculture and University Extension.

Hightower, M. 2003. Managing coal bed methane produced water for beneficial uses, initially using the San Juan and Raton basins as a model. Presentation to the New Mexico Water Resources Institute, Albuquerque, NM: Sandia National Laboratories. Available at wrri.nmsu.edu/conf/forum/CBM.pdf (accessed February 23, 2010).

Huang, F.Y.C., and P. Natrajan. 2006. Feasibility of using natural zeolites to remove sodium from coal bed methane-produced water. Journal of Environmental Engineering 132:1644-1650.

IOGCC (Interstate Oil and Gas Compact Commission) and ALL Consulting. 2006. A Guide to Practical Management of Produced Water from Onshore Oil and Gas Operations in the United States. Prepared for U.S. Department of Energy National Petroleum Technology Office. Available at www.gwpc.org/e-library/documents/general/A%20Guid e%20to%20Practical%20Management%20of%20Produced%20Water%20from%20Onshore%20Oil%20and%20Gas%2 0Operations%20in%20the%20United%20States.pdf (accessed March 5, 2010).

Lymbery, A.J., R.G. Doupe, T. Bennett, and M.R. Starcevich. 2006. Efficacy of a subsurface-flow wetland using the estuarine sedge Juncus kraussii to treat effluent from inland saline aquaculture. AquaculturalEngineering 34(1):1-7.

NRC (National Research Council). 2008. Desalination: A National Perspective. Washington, DC: National Academies Press.

Otton, J. 2006. Estimated Volume and Quality of Produced Water Associated with Projected Energy Resources in the Western US in Produced Water Workshop, April 4-5, Fort Collins, CO. Information Series No. 102, Colorado State University pp. 26-35.

Pollard, J., J. Cizdziel, K. Stave, and M. Reid. 2002. Selenium concentrations in water and plant tissues of a newly formed arid wetland in Las Vegas, NV. Environmental Monitoring and Assessment 135(1-3):447-457.

Rice, C.A., and V.F. Nuccio. 2000. Water produced with coalbed methane. U.S. Geological Survey Fact Sheet FS-156-00. Washington, DC: U.S. Department of the Interior. Available at pubs.usgs.gov/fs/fs-0156-00/fs-0156-00.pdf (accessed February 23, 2010).

RPSEA (Research Partnership to Secure Energy for America). 2009. An Integrated Framework for Treatment and Management of Produced Water: Technical Assessment of Produced Water Treatment Technologies. RPSEA Project 07122-12. Golden: Colorado School of Mines. Available at www.aqwatec.com/research/projects/Tech_Assessment_PW_Treat-ment_Tech.pdf (accessed February 16, 2010).

Schulz, R., and S.K.C. Peall. 2001. Effectiveness of a Constructed Wetland for Retention of Nonpoint-Source Pesticide Pollution in the Lourens River Catchment, South Africa. Environmental Science and Technology 35(2):422-426.

Stewart, D.R. and L. Takichi. 2007. Beneficial use of produced water—water as a valuable by-product. White paper presented to the 2007 Integrated Petroleum Environmental Consortium Conference, Tulsa, OK. Available at ipec.utulsa. edu/Conf2007/Papers/Stewart_74.pdf (accessed March 5, 2010).

Triolo, M., D.O. Ogbe, and A.S. Lawal. 2000. Considerations for water disposal and management in the development of coalbed methane resources in rural Alaska. Journal of Canadian Petroleum Technology 39: 41-47.

Veil, J.A. 2002. Regulatory Issues Affecting Management of Produced Water from Coal Bed Methane Wells. Prepared by Argonne National Laboratory for the Office of Fossil Energy, U.S. Department of Energy. Contract W-31-109-ENG-38. Available at bogc.dnrc.state.mt.us/website/mtcbm/CBM/ANL_CBM_Paper.pdf (accessed February 23, 2009).

Veil, J.A., M.G. Puder, D. Elcock, and R.J. Redweik, Jr. 2004. A White Paper Describing Produced Water from Production of Crude Oil, Natural Gas, and Coal Bed Methane. Argonne National Laboratory. Prepared for the National Energy Technology Laboratory, U.S. Department of Energy, under Contract W-31-109-Eng-38. Available at www.ead.anl. gov/pub/doc/ProducedWatersWP0401.pdf (accessed January 27, 2010).

Welch, J. 2009. Reverse osmosis treatment of CBM produced water continues to evolve. Oil and Gas Journal 107(37):45-50.

Wyoming DEQ(Department of Environmental Quality). 2000. Concentrations of Barium in the Surface Waters in Northeastern Wyoming Related to Discharges of Coal Bed Methane Produced Water. Cheyenne: State ofWyoming. Available at deq.state.wy.us/wqd/wypdes_permitting/WYPDES_cbm/downloads/12258-doc.pdf (accessed February 23, 2010).

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Zhao, H., G.F. Vance, M.A. Urynowicz, and R.W. Gregory. 2009. Integrated treatment process using a natural Wyoming clinoptilolite for remediating produced waters from coalbed natural gas operations. Applied Clay Science 42:279-385.

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