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Water for hydraulic fracturing: Difference between revisions

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==References==
==References==
<references>
<ref name="r1">FracFocus. 2014. Chemical Use In Hydraulic Fracturing. http://fracfocus.org/water-protection/drilling-usage.</ref>
<ref name="r1">FracFocus. 2014. Chemical Use In Hydraulic Fracturing. http://fracfocus.org/water-protection/drilling-usage.</ref>
</references>


==Noteworthy papers in OnePetro==
==Noteworthy papers in OnePetro==

Revision as of 12:32, 4 November 2014

Water is the most commonly used fluid in hydraulic fracturing, and it is used in large quantities. Chemicals are added to the water to aid in fracturing and prevent damage to the reservoir, and normally less than 1 percent of the fluid contents are chemical compounds. Because fracturing involves a large amount of water, innovations to reuse/recycle and safely dispose of the water are an important part of environmental stewardship.

Mechanism

Hydraulic fracturing is the process of pumping fluid into a wellbore at an injection rate too high for the formation to accept without breaking. During injection, the formation’s resistance to flow increases, and the pressure in the wellbore increases to a value called the break-down pressure, which is the sum of the in-situ compressive stress and the strength of the formation. When the formation “breaks down,” a fracture is formed, and the injected fluid flows through it.

Fluid not containing any solid (called the “pad”) is injected first, until the fracture is wide enough to accept a propping agent. The purpose of the propping agent is to keep apart the fracture surfaces once the pumping operation ceases, the pressure in the fracture decreases bellow the compressive in-situ stress trying to close the fracture. In deep reservoirs, man-made ceramic beads are used to hold open or “prop” the fracture. In shallow reservoirs, sand is normally used as the propping agent.

Chemicals additives

Water comprises 90 percent of typical fracking fluid, followed by 9.5 percent sand and 0.5 percent other chemical additives. The chemicals serve multiple functions, including limiting the growth of bacteria and preventing corrosion of the well casing. [1] The conditions of the well being fractured determine the number of chemical additives used. Typically, very low concentrations of between 3 and 12 additive chemicals will be used, depending on the characteristics of the water and the formation being fractured. Each component serves a specific purpose. For example, the predominant fluids used for fracture treatments in the gas shale plays are water‐based fracturing fluids mixed with friction‐reducing additives (called slickwater). The addition of friction reducers allows fracturing fluids and proppants, like sand or small ceramic beads, to be pumped to the target zone at a higher rate and reduced pressure than with water alone. Other additives include: biocides to prevent microorganism growth and reduce biofouling of the fractures; oxygen scavengers and other stabilizers to prevent corrosion of metal pipes; and acids to remove drilling mud damage within the near‐wellbore area.


References

  1. FracFocus. 2014. Chemical Use In Hydraulic Fracturing. http://fracfocus.org/water-protection/drilling-usage.

Noteworthy papers in OnePetro

Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read

Online multimedia

Burnett, David. 2012. New Options for Produced Water Treatment and Re-use in Gas/Oil Shale Fracturing. http://eo2.commpartners.com/users/spe/session.php?id=9382

Palmgren, Tor. 2013. Treatment Options for Reuse of Frac Flowback and Produced Water from Shales. http://eo2.commpartners.com/users/spe/session.php?id=11046

External links

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See also

Use this section for links to related pages within PetroWiki, including a link to the original PEH text where appropriate