Processing Magazine

California drillers prefer acidizing over fracking

August 14, 2013

<photocredit>Alexey Zaytsev/iStockphoto/Thinkstock</photocredit>

U.S. oil and gas production has been booming in the past few years as hydraulic fracturing (fracking) enables explorers to extract deposits previously impossible to reach. North Dakota, Texas and Pennsylvania have experienced a fracking explosion and it looks as if California may be next, as its Monterey Shale is believed to hold billions of barrels of oil. However, oil and gas companies drilling in California do not seem to be placing their bets on fracking.

California looks set to embrace a production technique called "matrix acidization", or acidizing for short. This will pose new challenges for state and federal regulators, who are still grappling with fracking legislation. It does not help that oil and gas companies are being extremely tight-lipped when it comes to their experiments with acidizing. Adding to the pile of concerns is the fact that the hydrofluoric (HF) acid used in this extraction process is one of the most hazardous chemicals that is also used by other industries as well as oil and gas.

California's apparent preference for acidizing and the potential consequences of the widespread use of this technology are the subject of a new report from think tank The Next Generation. It is the first in a series that will explore the environmental and public health implications of a Monterey Shale production boom.

According to author Robert Collier, California oil companies have established that fracking is not as effective as acidizing in the Monterey Shale. Fracking involves pumping a mixture of water and chemicals into underground rocks at high pressure, which fractures the formations and releases the fuel deposits. With acidizing, large amounts of HF acid are used. It dissolves the rocks and frees the oil. Given the low permeability and complexity of the Monterey Shale, acidizing reportedly produces better results than fracking.

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Although the technique is widely used, it is still virtually unregulated, Collier notes. Rules being drafted by state and federal regulators do not even touch on the subject of acidizing. The only piece of legislation to cover the technique is a bill currently being debated in Sacramento. It was put forward by Sen. Fran Pavley, who has been the driving force behind many climate laws passed in California in recent years.

Although oil industry executives admit to experimenting with various HF acid concentrations, they are all keeping quiet when it comes to concrete figures. The typical mixture used in acidizing has a HF concentration of less than 9%. However, experiments are being made with higher concentrations and pressures but the precise numbers are anyone's guess. Speculation was rife at the industry conference held in Bakersfield in May. Some executives attending the event expressed the belief that rival companies were testing HF concentrations of up to 30%. However, others dismissed this as impossible since concentrations that high would melt well casings.

The U.S. Centers for Disease Control puts HF among the most hazardous materials in industrial use. It is widely utilized in oil refineries as a catalyst in high-octane gasoline production. Compounding the danger is the fact that HF is extremely volatile at relatively low temperatures. It is liquid at cool temperatures but becomes a thick vapor cloud at 67.1 degrees F. The cloud does not disperse when it gets out in the open. It hovers close to the ground and can travel a long way, which means that any spills pose significant dangers to nearby settlements.