Produced water

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A shale gas well being drilled by a drilling rig in Pennsylvania

Produced water is a term used in the

oil industry or geothermal industry to describe water that is produced as a byproduct during the extraction of oil and natural gas,[1] or used as a medium for heat extraction.[2][3][4][5] Water that is produced along with the hydrocarbons is generally brackish and saline water in nature.[6] Oil and gas reservoirs often have water as well as hydrocarbons, sometimes in a zone that lies under the hydrocarbons, and sometimes in the same zone with the oil and gas. In geothermal plants, the produced water is usually hot. It contains steam with dissolved solutes and gases, providing important information on the geological, chemical, and hydrological characteristics of geothermal systems.[2]
Oil wells sometimes produce large volumes of water with the oil, while gas wells tend to produce water in smaller proportions.

As an oilfield becomes old, its natural drive to produce hydrocarbons decreases leading to decline in production. To achieve maximum

waterflooding is often implemented, in which water is injected
into the reservoirs to help force the oil to the production wells. In offshore areas, sea water is used. In onshore installations, the injected water is obtained from rivers, treated produced water, or underground. Injected water is treated with many chemicals to make it suitable for injection. The injected water eventually reaches the production wells, and so in the later stages of water flooding, the produced water's proportion ("cut") of the total production increases.

Water quality

The water composition ranges widely from well to well and even over the life of the same well. Much produced water is

U.S. Environmental Protection Agency
(EPA) in 1987 and 1999 indicates that during drilling and operations, additives may be used to reduce solid deposition on equipment and casings. Water produced from underground formations for geothermal electric power generation often exceeds primary and secondary drinking water standards for total dissolved solids, fluoride, chloride, and sulfate.

Water management

Diagram of an injection well for disposal of produced water

Water is required for both traditional geothermal systems and EGS throughout the life cycle of a power plant. For traditional projects, the water available at the resource is typically used for energy generation during plant operations.[11]

Historically, produced water was disposed of in large evaporation ponds. However, this has become an increasingly unacceptable disposal method from both environmental and social perspectives. Produced water is considered industrial waste.

The broad management options for re-use are

U.S. Environmental Protection Agency (EPA) for underground injection[12][13] and discharges to surface waters.[14] Although beneficial reuse for drinking water and agriculture have been researched, the industry has not adopted these measures due to cost, water availability, and social acceptance.[citation needed
]

Gravity separators, hydrocyclones, plate coalescers, dissolved gas flotation, and nut shell filters are some of the technologies used in treating wastes from produced water.[15]

Radioactivity

The use of produced water for road deicing has been criticized as unsafe.[16]

In January 2020, Rolling Stone magazine published an extensive report about radioactivity content in produced water and its effects on workers and communities across the United States. It was reported that brine sampled from a plant in Ohio was tested in a University of Pittsburgh laboratory and registered radium levels above 3,500 pCi/L. The Nuclear Regulatory Commission requires industrial discharges to remain below 60 pCi/L for each of the most common isotopes of radium, radium-226 and radium-228.[17]

See also

References

  1. S2CID 233073324
    .
  2. ^
    S2CID 248019293
    .
  3. S2CID 245682408
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  4. S2CID 247848365
    .
  5. S2CID 244823147
    .
  6. S2CID 211080984
    – via Springer Nature.
  7. ^ "What is produced water?". American Geosciences Institute - AmericanGeoSciences.org. Retrieved December 31, 2023.
  8. ^ "About Produced Water". Advanced Water Technology Center. Golden, CO: Colorado School of Mines. Retrieved 2016-05-14.
  9. doi:10.1093/ijlct/cts049
    .
  10. ^ Veil, John A.; Puder, Markus G.; Elcock, Deborah; Redweik, Robert J. (2004). A white paper describing produced water from production of crude oil, natural gas, and coal bed methane (PDF) (Report). Argonne, IL: US Argonne National Laboratory. ANL/EA/RP-112631.
  11. OSTI 1013997
    .
  12. ^ "Underground Injection Control Regulations and Safe Drinking Water Act Provisions". Washington, DC: U.S. Environmental Protection Agency (EPA). 2016-10-17.
  13. ^ "General Information About Injection Wells". EPA. 2016-09-06.
  14. ^ "Oil and Gas Extraction Effluent Guidelines". EPA. 2019-05-15.
  15. ^ Development Document for Final Effluent Limitations Guidelines and New Source Performance Standards for the Offshore Subcategory of the Oil and Gas Extraction Point Source Category (Report). EPA. 1993. pp. IX-15–IX-19. EPA-821-R-93-003.
  16. doi:10.1088/2515-7620/ac35be
    .
  17. ^ Nobel, Justin (21 January 2020). "America's Radioactive Secret". Rolling Stone.
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