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EPA Water Reuse Guidelines 2012 Now Available

Get your copy of the US EPA Water Reuse Guidelines 2012

The US Environmental Protection Authority (EPA) has just released its 2012  Water Reuse Guidelines. If you’re up for a bit of light reading (642 pages!) you might care to download the PDF at:

http://www.waterreuseguidelines.org/index.php?option=com_content&view=article&id=8&Itemid=14

Of particular interest to me is the detail relating to  Produced Water from Oil and Natural Gas Production (Ref Page 109 section 3.5.3 and Fig 3.6 refers).
While not specifically reuse of treated municipal effluent, the reuse of produced water that is generated as a by-product resulting from the extraction of crude oil or natural gas from the subsurface warrants discussion. Produced water, for the purposes of this discussion, is defined as any water present in a reservoir with a hydrocarbon resource that is produced to the surface with the crude oil or natural gas. There are three types of water associated with subsurface hydrocarbon reservoirs and production operations:

  • Formation water is water that flows from the hydrocarbon zone or from production activities when injected fluids and additives are introduced to the formation.
  • Produced water is generated when the hydrocarbon reservoir is produced and formation water is brought to the surface.
  • Flowback is water that returns to the surface within a few days or weeks following hydraulic fracturing performed on a
    natural hydrocarbon reservoir; this practice involves injection of large volumes of fracturing fluid into the hydrocarbon reservoir.

Recent advances in drilling techniques have led to an increase in production water from unconventional gas formations, including coal seams, tight sand, and shale deposits. These new techniques result in approximately eight barrels of water brought to the surface for every barrel of oil. This produced water is often highly saline and contaminated by hydrocarbons; it is a waste that requires treatment, disposal, and, potentially, recycling. Handling this produced water is an integral part of the oil and gas industry, and according to estimates by Clark and Veil (2009), the United States generates around 20.7 bbl/yr out of a worldwide total 69.8 bbl/yr (or 2.4 mgd of 8 mgd total; 9 ML/d of 30 ML/d total). The breakdown by state of produced water is shown in Figure 3-6. As might be expected, the quality of produced waters varies widely, ranging from water that meets state and federal drinking water standards to water having very high TDS concentrations.

The properties can vary considerably depending on geographic location, the source geological formation, and the type of hydrocarbon being extracted. When produced water contains certain constituents at high concentrations, it can threaten aquatic life if discharged to streams or other water bodies or used as irrigation water without treatment. As a result, produced water management is subject to applicable federal and state regulatory requirements, which are further described by the U.S. Department of Energy in an online resource, The Produced Water Management System (DOE, n.d.).

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Fig 3.6 – Estimates of Produced Water by State – EPA Water Reuse Guidelines 2012

It is of interest to note that under current regulations, produced water can only be utilized west of the 99 meridian and the practice is most contentious. Where produced water can be used, as with reclaimed water produced from treated municipal effluent, there are a variety of uses depending on the produced water quality and the level of treatment provided. Low TDS water sources, such as those common with coalbed methane production, may be reused with very little treatment (NRC, 2010). Higher TDS sources usually require a much higher level of treatment and may be limited in their end uses. End uses of treated, produced water include surface water flow augmentation, aquifer recharge, storage and recovery, crop irrigation, and livestock watering. Produced water may also be used for a variety of industrial purposes, especially in areas where freshwater resources are scarce. It is important to note that produced waters associated with hydraulic fracturing operations cannot be used as reclaimed water for alternative uses without extensive and expensive treatment operations, and reuse is limited to development of additional wells, with appropriate treatment.

Treatment of produced water is often required before the water can be put to beneficial reuse. The degree of treatment and the type of treatment technology used is based on a number of factors, including the produced water quality, volume, treated water quality objectives, options available for disposal of residual waste (such as concentrated brine), and cost. In oil and gas operations, it is sometimes necessary to use modular technologies that can be mobilized for localized treatment in the field versus building a fixed-based treatment facility in a central location. The overall objective is to develop a simple, cost-effective treatment solution capable of consistently meeting effluent treatment objectives. Because of the wide variation in produced water quality and treatment objectives in oil and gas fields across the United States, development of the best solution is challenging and often requires a combination of treatment technologies to meet the individual needs of each operator. Treatment technologies commonly used for produced water prior to reuse include oil-water separators, dissolved gas flotation or coalescing media separators, adsorption, and filtration targeted for removal of specific constituents from the produced water. As a result, the best approach must balance produced water quality, simplicity of operations, treatment objectives, and cost.

What blew me away with these figures is that the US is responsible for about 30% of the world’s total barrels of produced water volume pa looking at the overall world figures. Yes…we should be energy independent very soon!

What other snippets of useful information have you gleaned from the latest EPA Water Reuse Guidelines for 2012? Please do share your thoughts here. Thank you.

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