Produced water

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A shale gas well being drilled by a drilling rig in Pennsylvania Marcellus Shale Gas Drilling Tower 1 crop.jpg
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.

Contents

As an oilfield becomes old, its natural drive to produce hydrocarbons decreases leading to the decline in the production. To achieve maximum oil recovery, waterflooding is often implemented, in which water is injected into the reservoirs to help force the oil to the production wells. In the offshore areas, sea water is used. In the onshore installations the injected water is obtained from river, treated produced water or from the 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 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 brine, and most formations result in total dissolved solids too high for beneficial reuse. In oil fields, almost all produced water contains oil and suspended solids. [7] Some produced water contains heavy metals and traces of naturally occurring radioactive material (NORM), which over time deposits radioactive scale in the piping at the well. [8] [9] Metals found in produced water include zinc, lead, manganese, iron, and barium. [10] In geothermal fields, produced waters are classified into 3 chemical types: HCO3-Ca⋅Mg, HCO3-Na and SO4⋅Cl-Na. [2] The 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 Figure 2- Injection Wells for Produced Water (6847703607).jpg
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 direct injection, environmentally acceptable direct-use of untreated water, or treatment to a government-issued standard before disposal or supply to users. Treatment requirements vary throughout the world. In the United States, these standards are issued by the 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

Related Research Articles

<span class="mw-page-title-main">Geothermal energy</span> Thermal energy generated and stored in the Earth

Geothermal energy is thermal energy in the Earth's crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for millennia.

<span class="mw-page-title-main">Environmental remediation</span> Removal of pollution from soil, groundwater etc.

Environmental remediation is the cleanup of hazardous substances dealing with the removal, treatment and containment of pollution or contaminants from environmental media such as soil, groundwater, sediment. Remediation may be required by regulations before development of land revitalization projects. Developers who agree to voluntary cleanup may be offered incentives under state or municipal programs like New York State's Brownfield Cleanup Program. If remediation is done by removal the waste materials are simply transported off-site for disposal at another location. The waste material can also be contained by physical barriers like slurry walls. The use of slurry walls is well-established in the construction industry. The application of (low) pressure grouting, used to mitigate soil liquefaction risks in San Francisco and other earthquake zones, has achieved mixed results in field tests to create barriers, and site-specific results depend upon many variable conditions that can greatly impact outcomes.

<span class="mw-page-title-main">Bioremediation</span> Process used to treat contaminated media such as water and soil

Bioremediation broadly refers to any process wherein a biological system, living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer considerable advantages as it aims to be sustainable, eco-friendly, cheap, and scalable.

<span class="mw-page-title-main">Industrial wastewater treatment</span> Processes used for treating wastewater that is produced by industries as an undesirable by-product

Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater may be reused or released to a sanitary sewer or to a surface water in the environment. Some industrial facilities generate wastewater that can be treated in sewage treatment plants. Most industrial processes, such as petroleum refineries, chemical and petrochemical plants have their own specialized facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the regulations regarding disposal of wastewaters into sewers or into rivers, lakes or oceans. This applies to industries that generate wastewater with high concentrations of organic matter, toxic pollutants or nutrients such as ammonia. Some industries install a pre-treatment system to remove some pollutants, and then discharge the partially treated wastewater to the municipal sewer system.

<span class="mw-page-title-main">Supercritical carbon dioxide</span> Carbon dioxide above its critical point

Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure.

Enhanced oil recovery, also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. Although the primary and secondary recovery techniques rely on the pressure differential between the surface and the underground well, enhanced oil recovery functions by altering the chemical composition of the oil itself in order to make it easier to extract. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using primary and secondary recovery. According to the US Department of Energy, carbon dioxide and water are injected along with one of three EOR techniques: thermal injection, gas injection, and chemical injection. More advanced, speculative EOR techniques are sometimes called quaternary recovery.

Carbon dioxide (CO2) flooding is a process in which carbon dioxide is injected into an oil reservoir to increase the output when extracting oil. This is most often used in reservoirs where production rates have declined due to depletion.

<span class="mw-page-title-main">Fracking in the United States</span>

Fracking in the United States began in 1949. According to the Department of Energy (DOE), by 2013 at least two million oil and gas wells in the US had been hydraulically fractured, and that of new wells being drilled, up to 95% are hydraulically fractured. The output from these wells makes up 43% of the oil production and 67% of the natural gas production in the United States. Environmental safety and health concerns about hydraulic fracturing emerged in the 1980s, and are still being debated at the state and federal levels.

Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium and any of their decay products, such as radium and radon. Produced water discharges and spills are a good example of entering NORMs into the surrounding environment.

<span class="mw-page-title-main">Shale gas</span> Natural gas trapped in shale formations

Shale gas is an unconventional natural gas that is found trapped within shale formations. Since the 1990s a combination of horizontal drilling and hydraulic fracturing has made large volumes of shale gas more economical to produce, and some analysts expect that shale gas will greatly expand worldwide energy supply.

An injection well is a device that places fluid deep underground into porous rock formations, such as sandstone or limestone, or into or below the shallow soil layer. The fluid may be water, wastewater, brine, or water mixed with industrial chemical waste.

Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the subsurface. Globally, between 25 per cent and 40 per cent of the world's drinking water is drawn from boreholes and dug wells. Groundwater is also used by farmers to irrigate crops and by industries to produce everyday goods. Most groundwater is clean, but groundwater can become polluted, or contaminated as a result of human activities or as a result of natural conditions.

<span class="mw-page-title-main">Environmental impact of the petroleum industry</span>

The environmental impact of the petroleum industry is extensive and expansive due to petroleum having many uses. Crude oil and natural gas are primary energy and raw material sources that enable numerous aspects of modern daily life and the world economy. Their supply has grown quickly over the last 150 years to meet the demands of the rapidly increasing human population, creativity, knowledge, and consumerism.

<span class="mw-page-title-main">Fracking</span> Fracturing bedrock by pressurized liquid

Fracking is a well stimulation technique involving the fracturing of formations in bedrock by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants hold the fractures open.

<span class="mw-page-title-main">Environmental impact of fracking in the United States</span>

Environmental impact of fracking in the United States has been an issue of public concern, and includes the contamination of ground and surface water, methane emissions, air pollution, migration of gases and fracking chemicals and radionuclides to the surface, the potential mishandling of solid waste, drill cuttings, increased seismicity and associated effects on human and ecosystem health. Research has determined that human health is affected. A number of instances with groundwater contamination have been documented due to well casing failures and illegal disposal practices, including confirmation of chemical, physical, and psychosocial hazards such as pregnancy and birth outcomes, migraine headaches, chronic rhinosinusitis, severe fatigue, asthma exacerbations, and psychological stress. While opponents of water safety regulation claim fracking has never caused any drinking water contamination, adherence to regulation and safety procedures is required to avoid further negative impacts.

<span class="mw-page-title-main">Environmental impact of fracking</span>

The environmental impact of fracking is related to land use and water consumption, air emissions, including methane emissions, brine and fracturing fluid leakage, water contamination, noise pollution, and health. Water and air pollution are the biggest risks to human health from fracking. Research has determined that fracking negatively affects human health and drives climate change.

<span class="mw-page-title-main">Exemptions for fracking under United States federal law</span>

There are many exemptions for fracking under United States federal law: the oil and gas industries are exempt or excluded from certain sections of a number of the major federal environmental laws. These laws range from protecting clean water and air, to preventing the release of toxic substances and chemicals into the environment: the Clean Air Act, Clean Water Act, Safe Drinking Water Act, National Environmental Policy Act, Resource Conservation and Recovery Act, Emergency Planning and Community Right-to-Know Act, and the Comprehensive Environmental Response, Compensation, and Liability Act, commonly known as Superfund.

Air sparging, also known as in situ air stripping and in situ volatilization is an in situ remediation technique, used for the treatment of saturated soils and groundwater contaminated by volatile organic compounds (VOCs) like petroleum hydrocarbons, a widespread problem for the ground water and soil health. Vapor extraction has become a very successful and practical method of VOC remediation. In saturated zone remediation, air sparging refers to the injection a hydrocarbon-free gaseous medium into the ground where contamination has been found. When it comes to situ air sparging it became an intricate phase process that was proven to be successful in Europe since the 1980s. Currently, there have been further developments into bettering the engineering design and process of air sparging.

Hydraulic fracturing is the propagation of fractures in a rock layer by pressurized fluid. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas, or other substances for extraction, particularly from unconventional reservoirs. Radionuclides are associated with fracking in two main ways. Injection of man-made radioactive tracers, along with the other substances in hydraulic-fracturing fluid, is often used to determine the injection profile and location of fractures created by fracking. In addition, fracking releases naturally occurring heavy metals and radioactive materials from shale deposits, and these substances return to the surface with flowback, also referred to as wastewater.

Brine mining is the extraction of useful materials which are naturally dissolved in brine. The brine may be seawater, other surface water, groundwater, or hyper-saline solutions from several industries. It differs from solution mining or in-situ leaching in that those methods inject water or chemicals to dissolve materials which are in a solid state; in brine mining, the materials are already dissolved.

References

  1. ↑ Klemz, Ana Caroline; Weschenfelder, Silvio Edegar; Lima de Carvalho Neto, Sálvio; Pascoal Damas, Mayra Stéphanie; Toledo Viviani, Juliano Cesar; Mazur, Luciana Prazeres; Marinho, Belisa Alcantara; Pereira, Leonardo dos Santos; da Silva, Adriano; Borges Valle, José Alexandre; de Souza, Antônio Augusto U.; Guelli U. de Souza, Selene M. A. (2021-04-01). "Oilfield produced water treatment by liquid-liquid extraction: A review". Journal of Petroleum Science and Engineering. 199: 108282. doi:10.1016/j.petrol.2020.108282. ISSN   0920-4105. S2CID   233073324.
  2. 1 2 3 Su, Shujuan; Li, Ying; Chen, Zhi; Chen, Qifeng; Liu, Zhaofei; Lu, Chang; Hu, Le (2022-06-01). "Geochemistry of geothermal fluids in the Zhangjiakou-Penglai Fault Zone, North China: Implications for structural segmentation". Journal of Asian Earth Sciences. 230: 105218. Bibcode:2022JAESc.23005218S. doi:10.1016/j.jseaes.2022.105218. ISSN   1367-9120. S2CID   248019293.
  3. ↑ Song, Guofeng; Song, Xianzhi; Ji, Jiayan; Wu, Xiaoguang; Li, Gensheng; Xu, Fuqiang; Shi, Yu; Wang, Gaosheng (2022-03-01). "Evolution of fracture aperture and thermal productivity influenced by chemical reaction in enhanced geothermal system". Renewable Energy. 186: 126–142. doi:10.1016/j.renene.2021.12.133. ISSN   0960-1481. S2CID   245682408.
  4. ↑ Tao, Jian; Yang, Xing-Guo; Ding, Pei-Pei; Li, Xi-Long; Zhou, Jia-Wen; Lu, Gong-Da (2022-06-05). "A fully coupled thermo-hydro-mechanical-chemical model for cemented backfill application in geothermal conditions". Engineering Geology. 302: 106643. doi:10.1016/j.enggeo.2022.106643. ISSN   0013-7952. S2CID   247848365.
  5. ↑ Li, S.; Wang, S.; Tang, H. (2022-03-01). "Stimulation mechanism and design of enhanced geothermal systems: A comprehensive review". Renewable and Sustainable Energy Reviews. 155: 111914. doi:10.1016/j.rser.2021.111914. ISSN   1364-0321. S2CID   244823147.
  6. ↑ D. Atoufi, Hossein; Lampert, David J. (2020). "Impacts of Oil and Gas Production on Contaminant Levels in Sediments". Current Pollution Reports. 6 (2): 43–53. doi:10.1007/s40726-020-00137-5. ISSN   2198-6592. 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. ↑ Igunnu, Ebenezer T.; Chen, George Z. (September 2014). "Produced water treatment technologies". International Journal of Low-Carbon Technologies. 9 (3): 157–177. 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. ↑ Clark, C. E.; Harto, C. B.; Sullivan, J. L.; Wang, M. Q. (2010-09-17). "Water use in the development and operation of geothermal power plants". Osti.gov. doi:10.2172/1013997. 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. ↑ Bain, Daniel J; Cantlay, Tetiana; Garman, Brittany; Stolz, John F (1 November 2021). "Oil and gas wastewater as road treatment: radioactive material exposure implications at the residential lot and block scale". Environmental Research Communications. 3 (11): 115008. doi: 10.1088/2515-7620/ac35be .
  17. ↑ Nobel, Justin (21 January 2020). "America's Radioactive Secret". Rolling Stone.
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