There has been considerable public interest regarding the toxicity of chemicals used in hydraulic fracking, but little is known about acidizing, a process that uses acids to open up reservoirs of oil and gas shale. Little to no research has been done on what the chemicals of acidization are and what impact they could have on humans and the environment. This paper discusses the difference between acidizing techniques (acid maintenance, matrix acidization, and acid fracturing) and quantifies the amounts of the chemicals used in them. The Washington State’s Quick Chemical Assessment Tool (QCAT) is used to identify known F-graded toxins. These F-graded toxins are known carcinogens, mutagens, reproductive toxins, developmental toxins, endocrine disruptors, or persistent high acute toxicity chemicals. Furthermore the fate and transport of the F-graded acidization chemicals are modeled for ground and surface water identifying those of particular concern. The analysis of the present data shows there have been over 600 instances of acidizing (acid maintenance, matrix acidization, and acid fracking) in urbanized Southern and Central California from April 2013 to August 2015. There are close to 200 specific chemicals used in acidization, with at least 28 of them being F-graded hazardous chemicals. Some are used frequently in the 100’s-1000’s kg/treatment such as hydrofluoric acid, xylene, diethylene glycol and ethyl benzene. Close to 90 more chemicals are identified by non-specific names as trade secrets or reported with no quantity. The most commonly used acidizing chemicals are only 10% in common with the most commonly used hydraulic fracturing chemicals. Unlike hydraulic fracturing the fluid concentrations are high, ranging from 6-18% chemicals in water, and the waste returns highly acidic, in the range of pH 0-3. With this paper it is hoped that acidization becomes part of the larger discussion on concerns with oil exploration and be evaluated by appropriate authorities.

Acidizing oil wells: The chemicals and their impact

251st National Meeting (2016)

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