Drilling/completion fluids

Drilling Fluid Uses Acid and Salt To Improve Well Performance

The inventor of a new water-based drilling fluid believes the chemical process involved with his technology opens up natural fractures as drilling takes place to increase production in shale formations.

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The inventor of a new water-based drilling fluid believes the chemical process involved with his technology opens up natural fractures as drilling takes place to increase production in shale formations.

The key ingredients of the technology, called the Aquarius Drilling System, are readily available salts and acids that can be used in conjunction with proven completion techniques, or in some cases, in lieu of hydraulic fracturing.

“It is so simple that it is almost embarrassing that no one has used this before,” said Daryl Breese, an entrepreneur and former mud engineer with almost 30 years of experience. “You select the salt, select the acid, and rock and roll.”

After receiving significant interest from multiple companies, Breese said last year he agreed to sell exclusive rights to distribute the drilling fluid to a major service company whose name he could not disclose because of a contract agreement. He said the service company is continuing to test the technology and that he expects it to see wider use as those trials are completed.

Explaining how the patented drilling fluid works, he said that as long as its salt content is higher than that of the target formation, the shale will dehydrate through the process of “osmotic sucking.” As that takes place, the acid dissolves carbonate stringers and enlarges natural fractures and microfractures along the wellbore. In theory, this chemical tandem creates near-wellbore pathways for hydrocarbons to be produced and sends drill cuttings to the surface that are free of hydrocarbons and can be recycled.

The idea for the new drilling fluid came to Breese in 2009 after working as a contractor in the Marcellus Shale region of Pennsylvania for Newpark Resources, a large global provider of drilling fluids. Range Resources, the operator of one of the projects he was involved with, was searching for a novel way to eliminate the USD 80,000 it was spending per well to dispose of its drilling cuttings at hazardous waste sites.

The solution Breese said he helped develop was a water-salted-polymer-based drilling fluid that Newpark now markets as the Evolution drilling fluid system.

“It is really the first drilling fluid that enabled the cuttings to be approved for recycling instead of being thrown into a landfill at USD 4,000 to USD 5,000 per truckload,” he said. “They could actually use the drill cuttings for things like a rig base or a pad base—so that was a huge cost savings for them.”

Breese said the difference between the two systems is that his involves the use of acid. He added that the main reason companies have avoided acidizing while drilling is because they were afraid of rusting drillpipe even though, as he argues, “Drillpipe is cheap compared to hydrocarbon production.”

Breese said adding a 3% to 4% concentration of hydrochloric acid to his drilling fluid effectively dissolved limestone stringers inside a Marcellus gas well and helped improve the initial production rate by 50% compared with an offset well. Using drill cuttings or other geologic samples from the target formation, laboratory and field tests are needed to determine the types of acids and salts to use, as well as their concentrations and the exposure time needed to net the desired results.

He is hopeful that the technology may someday also be used in the United Kingdom to develop coalbed methane resources. But due to the widespread public opposition to hydraulic fracturing, the extraction of coalbed methane has been slow to materialize. Breese said his drilling fluid could provide the middle ground needed to get things moving in the UK because it can help achieve production without hydraulic fracturing. He said an operator can just “dial in” the acid concentration to create the desired cavity inside the coalbed to produce sufficient quantities of gas.

“Now you can say, we are not going to frac, we are just going to drill and we will keep the drilling fluid local to the pay zone and it is not going to affect the water supply at all,” he said.