Domestic Use

Fact Sheet - Domestic Use

   
 
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Many parts of the western United States are characterized by limited supplies of potable water. In light of the increasing demands, the costs of identifying and treating new water supplies continue to climb. Yet, many of these arid regions are home to oil and gas production, yielding substantial amounts of produced water. In the past, the costs to remove salinity and other parameters for purposes of meeting drinking water standards were prohibitively high. However, in recent years, costs to develop and deploy treatment technology have dropped. At the same time, communities are willing to pay higher prices for clean water. Treatment costs are now similar to water prices. These developments provide the crucial incentive for many water treatment technology developers wishing to enter the marketplace. PWMIS offers several fact sheets covering technologies designed to remove salt from produced water. This fact sheet focuses instead on the process of converting produced water into drinking quality or household quality water for domestic use. A related but important issue involves managing the concentrated byproduct stream that results from treating the produced water.

Desalination

  Photo of Texas A&M desalination trailer.Texas A&M desalination trailer; Source: J. Veil, Argonne National Laboratory.

Desalination technology has been employed for decades on ships and in coastal communities. In light of growing fresh water demands and diminishing supplies, more and more communities are looking toward desalination. Seawater offers an obvious raw water source for coastal areas. However, inland areas must look for other sources of saline water. Saline ground water has been used in some cases. In Texas, for example, several pilot tests have been conducted using produced water as the source water.

Texas A&M University established a program to develop a portable produced water treatment system that can be moved into oil fields to convert produced water to potable water. The idea was to augment scarce water supplies in arid regions, while also providing economic paybacks to operators in the form of prolonged productive lives of their wells (Burnett et al. 2002; Burnett and Veil 2004). The desalination trailer developed by the Texas A&M University has meanwhile conducted pilot tests using produced water as the water source at the following locations:

  • Fife oil well in Washington County, Texas
  • Neumann gas well
  • Darst oil field in central Texas
  • Key Energy produced water disposal well in Brazos, Texas

The treatment system-generated water met the applicable drinking water standards. The U.S. Environmental Protection Agency (EPA) has published a list of the contaminants and standards, which is available at http://www.epa.gov/safewater/consumer/pdf/mcl.pdf [PDF-external site]. Veil et al. (2006) show some of the data obtained during the pilot phase of the treatment system.

In addition to these tests, a sample of produced water from an oil field in Grimes County, Texas, was treated during a membrane desalination workshop held at Texas A&M in August 2006. Some brave attendees, including the author of this fact sheet, drank the water. According to staff of the Texas A&M University, the laboratory analysis of the water showed, "the input total dissolved solids (TDS) was 13,320 mg/L, and the output was 323 mg/L. Sodium input was 4,490 mg/L, and output was 127 mg/L. Chlorides input was 7,494 mg/L, and the output was 184 mg/L. Potassium input was 76 mg/L, and the output was 1.2 mg/L. This is better than our city water here in the Bryan/College Station area."

Additional information and data can be viewed on the website of the Texas A&M Global Petroleum Research Institute at http://www.pe.tamu.edu/gpri-new/home/ConversionBrine.htm.

Stewart (2006) describes a recent example from Colorado. A project near Wellington, Colorado, involves treating produced water from oil wells to serve as a raw water resource. The treated water will be used to augment shallow water aquifers, and ensure adequate water supplies for holders of senior water rights. The oil company is embarking on this project to increase oil production. A separate company will then purchase and utilize this water as an augmentation water source. The water will eventually allow the Town of Wellington and northern Colorado water users to increase their drinking water supplies by 300 percent.

  Diagram showing water flow through a treatment device.Diagram showing water flow through a treatment device; Source: J. Veil, Argonne National Laboratory.

Management of the Concentrate Byproduct
The technologies used to treat produced water generate two streams: a purified water stream and a concentrate stream that includes the impurities removed by the device. The level of the chemical constituents in the concentrate depends on their starting concentrations in the raw water and the operating parameters of the technology used (e.g., flow rate, pressure, type of filtration membrane or ion exchange resin, and frequency of device cleaning or backwashing). In addition to the constituents present in the produced water, operators generally add different chemical products to the treatment system for cleaning, anti-fouling, or other process control purposes. The concentrate also contains these products.

Management or disposal of the concentrate presents challenges to operators. Most situations in which produced water will serve as the raw water source are in dry, onshore areas where surface water discharge is not practical. The preferred management option is likely to be underground injection. If an operator is running water floods near the produced water treatment site, the concentrate could be reinjected as part of the water flood program. In all likelihood, regulators will likely to consider this a Class II well activity under the EPA's Underground Injection Control program. However, when the concentrate is injected solely for disposal (as opposed to enhanced oil recovery), regulators are currently debating the appropriate course of action. Veil et al. (2006) describe some of the issues associated with concentrate injection. The authors identify the regulatory standards that operators must consider.

References 
Burnett, D., W.E. Fox, and G.L. Theodori, 2002, "Overview of Texas A&M's Program for the Beneficial Use of Oil Field 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/David_Burnett_PWC2002.pdf [PDF-external site].

Burnett, D.B., and J.A. Veil, 2004, "Decision and Risk Analysis Study of the Injection of Desalination By-products into Oil-and Gas-Producing Zones," SPE 86526, presented at the SPE Formation Damage Conference, Lafayette, LA, Feb. 13-14.

Stewart, D.R., 2006, "Developing a New Water Resource from Production Water," presented at the 13th International Petroleum Environmental Conference, San Antonio, TX, Oct. 23-27. Available at http://ipec.utulsa.edu/Conf2006/Papers/Stewart_18.pdf [PDF-external site].

Veil, J.A., D. Burnett, and B. Grunewald, 2006, "Disposal of Concentrate from Treatment of Water for Beneficial Reuse," presented at the 13th International Petroleum Environmental Conference, San Antonio, TX, Oct. 23-27. Available at http://ipec.utulsa.edu/Conf2006/Papers/Veil_concentrate.pdf [PDF-external site].

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