Produced Water Treatment and Beneficial Use Information Center

Produced Water Beneficial Use Case Studies

Case Stusies Document (posted 6/14/2011).

Produced water can have a variety of beneficial uses, facilitating augmentation of fresh water resources, providing water for livestock and wildlife, for irrigation in arid regions, and for industrial applications. The following is a summary of recent and current beneficial use practices in the U.S.

Groundwater Augmentation

In Colorado, produced water from oil wells near Wellington has been treated as a raw water resource to augment shallow water aquifers1. The Wellington Oil Company, operating in Larimer County, Colorado, reported that 98.5% of its fluid production is produced water. The company utilized a deep injection well that re-injected the produced water into the underground formation from which it was pumped at a cost of approximately $1 per barrel2. The company needed to find an efficient and cost-effective way to manage produced water because their ability to dispose of the water has a direct impact on how many pumps can be online and thus how much oil they can recover. Therefore, the company embarked on a groundwater augmentation project to increase oil production. The steps to beneficial use of the water included3:

  • Pilot testing of water treatment processes to demonstrate water quality target and treatment process efficiency
  • Determination of non-tributary status of the groundwater by State Engineer
  • Water Quality Control Division permit assessment
  • Issuance of permit by Colorado Oil and Gas Conservation Commission
  • Construction of the water treatment plant
  • Completion of an RO drinking water treatment plant

The produced water at Wellington is treated through dissolved air floatation, pre-filtration, ceramic microfiltration, and activated carbon adsorption. The treated water is piped 4,000 feet to the groundwater recharge site, which is a rapid-infiltration pit that allows the treated produced water to percolate into a tributary aquifer. The shallow aquifer supplies water to a reverse osmosis plant that provides drinking water to the Town of Wellington and northern Colorado water users. The Wellington project provides environmental benefits, reduced waste disposal costs, and increased water supply; however, it required a significant financial investment as described in1.

Under Colorado water law, one of the legal hurdles for the Wellington reuse project was to identify which agency should issue the discharge permit. In this case, the Attorney General's (AG) office decided that the Colorado Oil and Gas Conservation Commission (COGCC) should issue the permit instead of the Colorado Water Quality Control Division (CWQCD). The COGCC was considering whether to promulgate new rules to accommodate projects like Wellington in the future.

IOGCC and ALL described an example in which CBM produced water has been injected into the aquifer of a city's well field4. In the example, the City of Gillette, WY, had depleted its local wells by unbalanced pumping for many years5. The well field was completed in Lower Fort Union sands at a depth of approximately 1,500 feet.

The city coordinated with a CBM production operator to install Class V aquifer recharge wells with the capacity equals to the produced water flowrate from a small CBM producing project.

Irrigation

Irrigation with produced water has become an attractive alternative for producers to manage and use water that otherwise will require an NPDES discharge permit. Thousands of acres in the Powder River Basin have been transformed to productive agricultural land using CBM produced water6. Most CBM product water is characterized as sodic water and is high in the sodium (Na+) concentration relative to concentrations of calcium (Ca2+) and magnesium (Mg2+). Excess sodium can lead to soil dispersion and loss of soil infiltration capability7. Some trace elements in produced water (e.g., boron) can harm plants when present in elevated concentrations.

ALL Consulting reported two examples from Wyoming8. The first project was conducted by Fidelity Exploration and Production. They irrigated livestock forage using only CBM produced water on some plots, and a blend of surface water and CBM produced water on other plots. Both tests resulted in adequate crop production; yet, the CBM produced water had to be applied at a higher rate because the plants did not utilize it as efficiently as the surface water blend. The second project was conducted by Williams, a CBM producer. Large areas were irrigated that previously had supported only the local drought-tolerant vegetation. Following irrigation with CBM produced water the land was able to support healthy grass crops that served as feed for livestock. Between watering intervals, Williams applied gypsum and other soil supplements to counteract the high SAR in the produced water.

DeJoia described a successful managed irrigation project9. After two years of applying soil amendments and CBM produced water, the test sites were converted from overgrazed range land to highly productive grasslands yielding livestock and wildlife benefits.

Paetz and Maloney17 reported on a project where 12,500 bbl/d of CBM produced water was used to irrigate 100 acres of arid land in the Powder River basin to produce a forage crop. The carefully managed approach resulted in the successful production, harvesting, and sale of the forage crop.

Operators intending to use CBM produced water without causing long-term harm to crop and soil employ managed irrigation. This technique involves careful monitoring of soil chemistry. Different soil supplements are added to provide the necessary chemical and mineral balance10. CBM produced water can be neutralized with an acid like sulfur. Calcium amendments such as gypsum can be added to offset the sodium-rich water. Adding sulfur and gypsum is equivalent to adding standard fertilizers because these standard fertilizers often contain the same elements.

More than 30 options exist under the category of managed irrigation. Several automatic and manual irrigation systems are available, including: center pivot sprinklers, side-roll/wheel line sprinklers, hand-moved or fixed solid set sprinklers, big gun sprinklers, surface drip, subsurface drip, gated pipe flood and ditch flood6. Ranchers are commonly using center pivot and side-roll sprinklers.

More recently, the use of subsurface drip irrigation method has grown rapidly. BeneTerra, LLC, a water management company, has developed subsurface drip irrigation technology to disperse CBM produced water11. The system works by evenly applying small amounts of water over a large surface. Produced water is filtered, treated, and pumped through a labyrinth of polyethylene tubing which spreads it uniformly across the land. The tubing has emitters attached to the inside, which regulate flow from openings on the tubing. It is placed in the soil with a chisel plow to depths ranging from 18 to 48 inches. Plants derive moisture from roots in the subsoil while the topsoil remains relatively dry. Haying operations can continue while the field is being irrigated. Heavy equipment cannot compact dry soil and weeds cannot germinate. BeneTerra irrigation systems are designed to utilize the native calcium and magnesium already present in the soil to offset the effects of sodium. Then the salts percolate to a lower depth in the soil. Because the CBM water is naturally warmer, freezing is not an issue. This system provides year-round water dispersal for energy operators while producing bountiful crops.

Livestock Watering

Some CBM projects on ranch land have created impoundments or watering stations to provide CBM produced water as a drinking water source for livestock7. ALL Consulting reported the results from tests at the 7 Ranch near Gillette, Wyoming, where livestock are watered from small reservoirs containing CBM produced water8.

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Animals can tolerate a wide variety of water quality. However, highly saline water or water containing toxic elements may be hazardous to animals and may even render the milk or meat unfit for consumption. In evaluating the usability of any particular water, a number of factors should be considered, including local conditions, availability of alternate supplies, source water quality, seasonal changes, age, species, and health conditions of the animals, and composition rate12.

Wildlife Watering and Habitat

Some CBM projects collect and retain large volumes of produced water in impoundments that may have surface areas of several acres. The impoundments provide a source of drinking water for wildlife and offer habitat for fish and waterfowl in an otherwise arid environment. It is important to ensure that the quality of the impounded water will not create health problems for the wildlife8. ALL Consulting1 also presents information on siting and construction of wildlife watering impoundments.

Fisheries

ALL Consulting reported that untreated CBM produced water is currently being used to sustain privately owned fishponds in some states, including Wyoming8. Meanwhile the State of Wyoming discontinued fish stocking programs in certain ponds due to a general lack of available water volume needed to sustain the systems. CBM produced waters are now being beneficially used to supplement the ponds, allowing for continuation of the State’s stocking program. The application and success of this use would depend on applicable state guidelines, public demand, water quality, drainage, and geographic region. Water rights rules and regulations vary by state; it is important to determine local water rights as they apply to this management option.

Constructed Wetlands

Constructed wetlands are an alternative treatment and use option for oil and gas produced water13. Constructed wetlands could increase wildlife distributions, reduce displacement, and enhance diversity by improving quality habitat2. Research sponsored by Marathon Oil Company in 2000 involved construction of an artificial sedge wetland system to treat CBM produced water. The purpose of the project was to determine if constituents found in CBM produced water, mainly iron, barium, and unbalanced SAR, could be treated cost-effectively. A report by Montana State University further supported the results, concluding that "clean water is needed to supplement sodicity and saline treatment by vegetation and soil14."

Wetlands may have significant ecological and environmental impact. They provide areas that can be utilized by wetland birds and animals and aquatic life. Wetlands can also be utilized for livestock and wildlife watering purposes15. On the other hand, the contaminants in CBM produced water may affect fish and wildlife. For example, the research conducted by the USGS has demonstrated acute and chronic sodium bicarbonate toxicity to aquatic species. CBM produced water discharges containing selenium in concentrations above 2 µg/L may cause bioaccumulation in sensitive species16. In addition, if the wetlands are constructed as part of direct discharge, they will change habitat from increased flows and increased erosion. Impacts to downstream users due to direct discharges would be comparatively higher with increased flows during traditional low flow periods and increased sedimentation from erosion.

References

  1. ALL-Consulting, Handbook on coalbed methane produced water: Management and beneficial use alternatives, 2003, for the Ground Water Protection Research Foundation, U.S. Department of Energy, and U.S. Bureau of Land Management, http://www.all-llc.com/CBM/BU/index.htm
  2. Johnston, C., EPA regulation of discharges to surface waters, IPEC, Houston, TX, November 6-9, 2007.
  3. US EPA, 1996, NPDES Permit Writers’ Manual, EPA/833/B-96/003. http://www.epa.gov/guide/pharm/guidance/
  4. Wyoming Department of Environmental Quality, 2005, Memo updating watershed permitting approach, http://deq.state.wy.us/wqd/WYPDES_Permitting/WYPDES_cbm/Pages/CBM_Watershed_Permitting/Downloads/Wagner_Memo_01_05195.pdf [PDF]
  5. US EPA/Office of Ground Water and Drinking Water, 2001, Aquifer recharge wells and aquifer storage and recovery wells, Class V UIC Study Fact Sheet. http://www.epa.gov/safewater/uic/class5/pdf/study_uic-class5_classvstudy_fs-aq_rechrg_wells.pdf [PDF]
  6. Wyoming Department of Environmental Quality, UIC Program, http://deq.state.wy.us/wqd/groundwater/uicprogram/downloads/FAQ%20-%20CBM%20Injection%20Wells%20-%20Regulations%20to%20
    Protect%20USDWs%20Nov%2005%20Final.pdf
    [PDF]
  7. Ayers, R. S., Westcot, D. W., Water quality for agriculture, 1994, Irrigation and Drainage Paper, 29 Rev. 1, http://www.fao.org/DOCREP/003/T0234E/T0234E00.htm#TOC
  8. US EPA, 2004, Guidelines for water reuse, EPA/625/R-04/108.
  9. Montana State University, Frequently Asked Questions. Coal Bed Methane (CBM), 2003, http://waterquality.montana.edu/docs/methane/cbmfaq.shtml
  10. Produced Water Management Technology Descriptions Fact Sheet http://www.netl.doe.gov/technologies/pwmis/techdesc/
  11. Chhabra, R., Soil salinity and water quality, Rotterdam, Brookfield, VT, 1996.
  12. Alabaster, J. S., Lloyd, R., Water quality criteria for freshwater fish. Butterworths, 1980, United Nations/Food and Agriculture Organization,
  13. Colorado Department of Public Health and Environment/Water Quality Control Commission, 2008, The basic standards and methodologies for surface water (5 CCR 1002-31), Regulation No. 31. http://www.cdphe.state.co.us/regulations/wqccregs/100231wqccbasicstandardsforsurfacewater.pdf [PDF]
  14. The use of coal bed methane product water to enhance wetland function, 2003, http://waterquality.montana.edu/docs/methane/wetlandenhancement.shtml
  15. Kuipers, J. R., Technology-based effluent limitations for coalbed methane produced wastewater discharges in the Powder River Basin of Montana and Wyoming, 2004, Draft Report prepared for Northern Plains Resource Council Billings, MT, http://www.northernplains.org/files/Final_BPJ_BAT_8_25_04.pdf [PDF]
  16. Lynch, K. E., Agency Collection Activities: Coalbed methane extraction sector survey, 2008, Prepared by Trout Unlimited to EPA Docket Center,
  17. Paetz, R.J., and S. Maloney, 2002, "Demonstrated Economics of Managed Irrigation for CBM Produced Water," presented at the 2002 Ground Water Protection Council Produced Water Conference, Colorado Springs, CO, Oct. 16-17. Available at http://www.gwpc.org/meetings/special/PW%202002/Papers/Steel_Maloney_PWC2002.pdf [PDF]