UCLA Report Misleads Public on California “Acidizing” Techniques

Recently, researchers at University of California, Los Angeles (UCLA) released a study claiming that various chemicals used in the three common “acidizing” processes associated with oil exploration — acid maintenance, matrix acidizing and acid fracturing  — are identified as “F”-graded toxins according to Washington State’s Quick Chemical Assessment Tool (QCAT), which is based on methodology developed by the United States Environmental Protection Agency’s (EPA).

The identification of these chemicals is not a problem itself. Potentially toxic chemicals surround us every day, and are commonly used in household and industrial applications. Proper safety precautions, and proper dilution, are critical. However, the authors’ assertion that the chemicals used in oilfield acidizing processes pose a major risk to humans via contaminated drinking water is completely unfounded and seems designed to needlessly scare the public.

Claiming that “chemicals,” regardless of concentration or application, are a source of potential harm without evidence of contamination is a common tactic used by opponents of hydraulic fracturing (fracking), as EID has previously shown. The UCLA researchers appear to be relying on the same tactic when discussing acidizing.  As the report states:

“There are many different types of chemicals used in acidizing, and the risk of each is dependent on the chemical’s exposure, toxicity, fate and transport, transformation, and cumulative and synergistic effects with other chemicals. Many of these factors have not been studied. Here we focus on the chemicals’ human exposure pathways through water. Table 2 lists the surface and subsurface chemical release mechanisms into waterways from oil stimulation, production, and wastewater management and disposal activities in California.”

Acids (like hydrochloric acid and hydrofluoric acid) are commonly used by a variety of industries and naturally must be handled with care.

Acidizing is safe; contamination is “highly unlikely”

The researchers admit that acidizing techniques are nothing new.  The use of acid in oil exploration dates back over 120 years, with the modern-day use of acid in stimulation beginning in the 1930s. Additionally, the use of acid in oil development is common and heavily regulated, with beneficial applications ranging from corrosion control, descaling, lubrication cleaning, lubricating and descaling the wellbore, to preventing corrosion to increasing the permeability of a reservoir to produce more oil. The authors concede that these applications are routine:

“Acid maintenance is a routine procedure to remove deposits from on well surfaces, also known as scale. In acid maintenance, operators inject acid solutions at a specific location in the wellbore to react with the scale. The scale is thus cleaned off the surfaces of the wellbore and equipment without any acid penetrating into the formation (Robertson, Chilingarian, and Kumar 1989).”

Even in the case of matrix acidizing, where a solution of water, acid and additives is injected into a formation to improve permeability, the process minimizes the risk of possible contamination by only extending a few feet into the formation. As the authors write:

“Matrix acidizing in carbonate formations can nonetheless create small channels or tubes called wormholes that can propagate as much as 6.1 m (20 feet) into the formation as carbonates are easily dissolved by acids…However, in sandstone, acid dissolution is limited to a much smaller distance of 0.3-0.6 m (1-2 feet) into the formation because the silica matric is harder to dissolve.”

This holds true for acid fracturing as well, which is similar to matrix acidizing but carried out under much more pressure. As the report states,

“For acid fracturing to be able to etch channels in the fracture walls, the rock has to be soluble in acid, and the acid should not excessively leak off into the formation without reacting. Thus this technique is mainly use in carbonate formations (Williams, Gidley, and Schechter 1979).”

Elaborating on this point, researchers concede that water contamination from fractures created by fracking extending into aquifers is “highly unlikely,” and contamination even more improbable in the case of acid fracturing. As the researchers state,

“Modeling work suggests that hydraulic fracturing stimulation fluid contaminating aquifers by connecting pathways is highly unlikely, happening on a 1000 – 100,000 year scale (Kissinger et al. 2013; Gassiat et al. 2013; Flewelling and Sharma 2014). It is even more unlikely for wormhole pathways to reach an aquifer, because they do not extend very far.” [Emphasis added]

“Full disclosure”

In addition to inaccurately suggesting that drinking water contamination can occur, the study’s authors employ another common method used to scare and mislead the public about oil and natural gas production: the assertion that most of the chemicals used are not disclosed or purposefully withheld.  According to the report:

“Although information [about the chemicals used] is required to be reported, self-reporting reduces transparency; there is no real-time way to validate information or that all information is being reported. Sometimes information is withheld because of trade secrets. Thus, the information may not be representative of consistent and transparent data collection.”

While the authors attempt to cast doubt on the transparency of reporting the components that make up the fluid used in fracking or acidizing, they imply that companies are not held accountable or purposefully try to obscure this information; this couldn’t be farther from the truth.

According to the most recent version of the California Statutes and Regulations for Conservation of Oil, Gas, & Geothermal Resources from the Department of Oil, Gas, and Geothermal Resources (DOGGR), “full disclosure” of the components in fracking and acid stimulation fluids is legally required. As the regulation states:

“Full disclosure of the composition and disposition of well stimulation fluids, including, but not limited to, hydraulic fracturing fluids and acid stimulation treatment fluids, shall, at a minimum, include:… (B) A completely list of the names, Chemical Abstract Service (CAS) numbers, and maximum concentration, in percentage by mass of each and every chemical constituent of the well stimulation treatment fluids used. If a CAS number does not exist for a chemical constituent, the well owner or operator may provide another unique identifier, if available…” (p.32)

As for the authors’ claim that “sometimes information is withheld because of trade secrets,” again, this is a misrepresentation of the facts. While some information is not publically disseminated to protect the substantial time and money invested in these techniques, that doesn’t mean this information is withheld from those who need it. Instead, the information is readily available to government regulators, officials, and medical professionals to ensure the health and safety of the public.

As DOGGR states:

“The division shall develop a timely procedure to provide trade secret information in the following circumstances: (A) To an officer or employee of the division, the state, local governments, including, but not limited to, local air districts, or the United States, in connection with the official duties of that officer or employee, to a health professional under any law for the protection of health, or to contractors with the division or other government entities and their employees if, in the opinion of the division, disclosure is necessary and required for the satisfactory performance of a contract, for performance of work, or to protect health and safety.” (p. 37)

Chemicals Are Widely Used

While the authors of this study try to scare the public away from acid techniques by listing chemicals classified as “F-grade, or claiming the disclosure of these chemicals is intentionally obscured, they fail to acknowledge a simple fact: many of these chemicals are widely used and are available for sale at your local home improvement store.

As EID previously reported, many of the chemicals found in fracking fluid are also used in household items such as dish soap, carpet cleaner, shampoo and glue.  Several of the same chemicals are used in acidizing and, yes, receive an “F” grade from QCAT for being toxic. However, without establishing a link to water contamination, or providing the possible concentrations of chemicals one could be exposed to, listing these chemicals serves little purpose for the general public beyond scaring them.

A good example of a toxic chemical in everyday use is hydrochloric acid (or “muriatic” acid). According to the Agency for Toxic Substances and Disease Registry:

“Direct contact with aqueous solutions of hydrogen chloride or with concentrated vapor can cause severe chemical burns.

Children are more vulnerable to toxicants affecting the skin because of their relatively larger surface area:body weight ratio.


Ingestion of concentrated hydrochloric acid can cause severe corrosive injury to the lips, mouth, throat, esophagus, and stomach.”

Scary stuff, to be sure. However, we do not think twice about letting our children swim in pools that have had this acid added to the water because the concentration is diluted enough to benefit the pool but not harm the swimmer.

UCLA’s parking lots: be afraid!

If the researchers wanted to scare people about even greater chemical exposure risks, they could have looked much closer to home: the parking lots on UCLA’s campus.

Each one of the vehicles on campus (including the researchers’) in the school’s 24,000 parking spaces has a tank of gasoline that contains many of the same chemicals used in acidizing. It’s not just the gas tank though; car batteries and electric vehicle batteries contain several chemicals found on California’s Proposition 65 list of potentially harmful chemicals, such as nickel, lead, and lithium cobolt oxide (derived from lithium carbonate).

So, let’s say around 20,000 vehicles are parked on campus during classes, each with about 10 gallons of gasoline – that’s 200,000 gallons of flammable and toxic material that students, professors and staff are walking and breathing around every day!  Compared to this, the implied risks associated with acidizing are actually very low, especially since the researchers don’t quantify possible exposure concentrations, nor provide proof that water contamination from acidizing exists.

Anti-fracking funders

It is worth noting that this study was partially funded by The Schmidt Family Foundation, an organization committed, in part, to stopping fracking and fossil fuel production. In 2014 alone, the foundation gave over $2.2 million in grants to organizations and projects opposing fracking and oil and natural gas production. Some of these grants include; $250,000 to the Sustainable Markets Foundation “to support the Californians against Fracking project,” $300,000 to the Sierra Club “to support the Beyond Natural Gas Campaign,” and $150,000 to Food & Water Watch “to support raising environmental and health risks awareness surrounding fracking in CA.”

While it is possible that the study would have looked no different if it hadn’t shared a funding source with some of the most vocal anti-energy activist groups, it does shed light on the possible motives behind the language used to imply dangers to the public from the acidizing processes used in oil exploration when the facts don’t support such implications.


While the UCLA study attempts to mislead the public about the safety of acidizing techniques by making claims about the toxicity of the chemicals used in acidizing processes. But, like the ever-increasing body of scientific understanding about fracking and water, the researchers fail to link the chemicals from acid treatments to contamination of water resources, even acknowledging that contamination is “highly unlikely”.

Oil and natural gas production in California provides jobs, benefits the economy, and improves our nation’s energy security and our environment. None of these benefits, of course, should come at the expense of safe drinking water. It is therefore fortunate that techniques like acid maintenance, matrix acidizing and acid fracturing (along with hydraulic fracturing) have been safe and routine parts of energy development in California for decades if not a century due to both industry best practices and strict environmental regulations. To suggest otherwise is simple fear mongering.


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