With all the recent focus on hydraulic fracturing, another well completion process, acid fracturing has taken a back seat. But now Senate Bill 4 - a bill written by Senator Fran Pavley that regulates hydraulic fracturing - has recently been amended to include all well stimulation techniques, included the ones that use acid. Local group Citizens for Responsible Oil and Gas (CFROG) are endorsing the bill.
“I haven’t been this freaked out about acid since the 60’s,” said John Brooks, Oak View resident and president of Citizens for Responsible Oil and Gas (CFROG) at the recent Ojai Valley Democrats meeting. “I’m told that 8 out of every 10 wells will be completed with acidization.”
Acid is used in different ways to stimulate oil production. In matrix acidization the acid is targeted within the wellbore itself without the intention of affecting the rock enclosing the reservoir, just loosening up the oil in the reservoir and helping remove anything that would impede the oil from being extracted. With acid fracking the acid is aimed at breaking apart the reservoir to release the oil and gas. Instead of using high pressure water to break apart the rock as in hydraulic fracturing, the acid works to melt away the rock, releasing the oil and gas into the reservoir to be pumped out.
Different types of acid are used depending on the type of formation being worked in. Hydrofluoric acid works best in formations that are silica/sandstone based while hydrochloric acid functions well in areas where limestone (carbonate) formations are holding the oil and gas.
“The Monterey formation [which is under most of Ventura County] has both types of formations,” said Dr. Tom Williams PhD in Geology/Zoology from UC Berkeley and decades of experience as a consultant for oil companies all over the world. “So both acids may be used.”
At low concentrations hydrofluoric acid irritates the skin, eyes and respiratory system. At higher levels it causes burns, severe injury, and death. It is considered a carcinogen, and is recognized as especially toxic due to its ability to quickly pass through the skin to underlying tissue. Hydrogen gas can be released if hydrofluoric acid comes in contact with certain metals. According to the EPA short term inhalation exposure to hydrochloric acid (hydrogen chloride HCL) “may cause eye, nose and respiratory tract irritation and pulmonary edema,” and long term “occupational exposure has been reported to case gastritis, chronic bronchitis, dermatitis and photosensitization in workers.”