Coalbed Methane Produced Water In The Western Us

BOX 4.2

Making "Bad" Produced Water "Good": Achieving Augmentation with Water Produced from Oil and Gas Operations—in Wellington, Colorado

The potential opportunities for use of produced water are numerous, but few of those opportunities have been realized to any level of significance. One case that represents the extreme in making beneficial use of produced water is that of the community of Wellington, Colorado, and its partnership with an environmental consulting firm from Fort Collins, Colorado. Wellington, a community outside Fort Collins, Colorado has experienced rapid expansion in population over the past two decades, but without similarly increasing the availability of desired municipal water supplies. A combination of drought and senior water rights holders' demands for water for irrigation have put the city of Wellington in a situation with slowly depleting storages of water in underground aquifers that the city relies on for municipal water.

The Wellington project is treating water produced from conventional oil wells as a raw water resource to augment shallow water aquifers to ensure adequate water supplies for holders of senior water rights downstream of Wellington. The process is known as aquifer storage and recovery (ASR). A participating oil company engaged with the environmental consulting firm and Wellington to allow the petroleum operator to increase its oil production, resulting in more produced water than they could adequately manage. The environmental consulting firm agreed to take possession of the then use the treated water as an augmentation water source to resupply the aquifer from which Wellington was drawing water for municipal use. The augmentation water mixes with water within the shallow alluvium, down gradient of the Wellington municipal water withdrawal, and subsequently satisfies the water rights of downstream senior water rights holders.

One of the unique features of this project, in addition to transforming produced water, which normally would be considered a waste, into "good" water used to satisfy an augmentation requirement imposed on the community of Wellington, is the legal recognition of some produced waters as "new" water, or new water resources for the western United States. In addition, this whole new approach to "produced water" as a beneficial use product and augmentation source of water has tested the premise of the "nontributary" nature of water produced from conventional oil wells, the assignment of ownership of "new" water, and how water resource management and regulatory agencies approach new and novel beneficial use applications of produced water.

SOURCES: See Stewart (2006); Stewart and Takichi (2007); Henderson (2007); Veil et al. (2004); and www.netl.doe. gov/technologies/pwmis/techdesc/injectfut/index.html (accessed March 9, 2010).

watering and wildlife use and consumption directly after it emerges at the well head with no prior treatment. Other produced water may be of suitable quality for establishing and maintaining wetlands. With current technologies, CBM produced water can be treated to attain the quality necessary to support any beneficial use, but at variable costs. At present, however, water coproduced with CBM has been largely neglected for beneficial use, even where concentrations of dissolved solids and other contaminants are within regulatory guidelines for potable agricultural or livestock use, such as described earlier for parts of the

Powder River Basin. With appropriate management, assurances of compatibility between CBM produced water quality, crop sensitivity to salinity, and soil properties, CBM produced water may be used to augment site-specific water supplies for irrigated agriculture in some areas.

State regulatory frameworks for environmental management and mineral and water rights have been the greatest influence on the way in which produced water can and has been used in the western states (see Chapter 3). This influence extends to any market value, whether real or perceived, of produced water used for beneficial purposes. Today, western cities look to enhance their water supplies, sometimes at significant cost. The societal and economic costs that may be incurred by not considering CBM water for beneficial use in an arid part of the United States are not usually discussed with regard to CBM produced water management.

In concept and on paper, putting CBM produced water to beneficial use would seem to be a desirable and relatively easy objective to achieve. In reality, management or discharge of CBM produced water for the specific purpose of achieving beneficial use is potentially economically burdensome, complex, and challenging. For example, in the case of waterfowl habitat enhancement, either constructing or intentionally augmenting existing ponds and wetland areas by discharging CBM produced water on the landscape typically requires an NPDES permit. The process of preparing and submitting applications for such a permit is both economically burdensome and labor intensive for the applicant. Consideration must be given to the quality of the discharged water, the potential for flooding, seepage to downgradient ephemeral channels or shallow alluvium, alteration in the ecological community resulting from changes in hydrology of the wetland, short- and long-term impacts of discharge on the chemistry of the impounded water, and the longevity or tenure of available supplies of produced water to support waterfowl habitat. Consideration also needs to be given to the potential consequence of discontinuation of the augmentation as CBM production diminishes.

Another example might be that of instream flow augmentation and corresponding supplementation of downstream irrigation water sources. Discharge requires an NPDES permit, which might require treatment of discharged water to assure protection of aquatic species. The rigor or level of treatment of water to achieve aquatic species protection may far exceed the treatment level that would be required to support sustainable irrigation—yet both beneficial uses are intended with the same CBM produced water discharge, creating added challenges with regard to permitting, compliance, and economics of managing the CBM produced water.

Discharging produced water to an existing stream for the purpose of fisheries enhancement could result in blended water that is not of an acceptable quality for downstream irrigation uses. The beneficial use opportunity is dictated by the quality in stream. Acceptable quality for one beneficial use may preclude use of the water for other uses, or may even

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