Acid fracturing and matrix acidization, also often termed acidization, are unconventional oil stimulation techniques for both shallow and deep oil reserves throughout the United States. There is little public awareness or available information on what the technique is and what chemicals are used for it. Using recent data available through the California’s Department of Conservation, Division of Oil, Gas, and Geothermal Resources (DOGGR) and the South Coast Air Quality Monitoring District (SCAQMD) we have mapped out where acidization is occurring in California and compiled a list of the chemicals and their concentrations used in these acidization techniques. Acidization is reported to be in use throughout central California, especially in Kern Country, and throughout the Southern California region. From our analysis we found that there have been 52 instances of matrix acidization events in Central and Southern California from January to September of 2014. There have been 371 reported cases of acidizing from April 2013 to September 2014. These general acidizing events include well bore cleanout, acid fracturing, and/or matrix acidization in Southern California.<br/><br/>There are over a hundred different chemicals used in acidization many of them similar to those used in hydraulic fracturing. The range of chemicals include some less environmentally harmful ones, like cinnamaldehyde or citric acid, and others that we suspect can cause harmful environmental impacts, such as formaldehyde and formic acid. This paper lists the chemicals and the amounts used. Hydrochloric acid is used in the highest concentration in most of these treatments, in the 100,000’s of mg/L. In other treatments benzoic acid and hydrofluoric acid are used in the highest concentrations, in the 10,000s of mg/L. Other additives like ethylene glycol monobutyl ether, formic acid, ethoxylated hexanol, are used in the 10,000’s mg/L. The amounts of chemicals used in matrix acidization have limited government oversight. With this paper we hope that acidization becomes part of the larger discussion on concerns with unconventional oil stimulation techniques.

Chemicals used for matrix acidization, an unconventional oil stimulation technique

249th National Meeting (2015)

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