Companies in drought areas have begun looking at liquefied petroleum gas gel for hydraulic fracturing as a way to reduce dependence on already-scarce water supplies.
Gas gel presents a potentially viable replacement to the millions of gallons of water used in the fracking process at each well site, said John McLennen, an associate professor of chemical engineering at the University of Utah.
Also referred to as dry fracking, the process does not involve water. Instead, highly pressurized gas is injected directly into a formation to crack the rock.
“Conceptually it’s a great idea. People are definitely looking for water substitutes,” he said.
While the gel reduces the use of water dramatically and can benefit both producers and operators, many companies have not incorporated the gel into their operations due to the explosive and flammable nature of propane, McLennen said.
Under the Colorado Oil and Gas Association, companies have the autonomy to make individual technology related decisions, spokesperson Dan Haley said.
“There are a number of different techniques that Colorado companies use in oil and gas development,” said Doug Flanders, COGA director of policy and external affairs. “The most important factor when deciding which technique works best is the type of formation where you’re trying to extract oil or gas.”
McLennen said that the advantages to gel use have yet to be fully researched or substantiated. However, it has the potential to drastically reduce water use in areas were the resource is expensive because of drought or high transportation costs.
On average, each well requires between 1 million and 5 million gallons of water during fracking operations.
In Colorado, hydraulic fracturing operations account for approximately .08 percent of water consumed statewide, with companies working on ways to re-use and recycle water annually, Haley said.
The gel would help to solve the challenge of recycling flow-back water from wells, said Jason Munro, president of GASFRAC based in Calgary, Alberta.
Oil and gas companies dispose of water that cannot be recycled, using Colorado Oil and Gas Conservation Commission guidelines where approximately 60 percent goes into underground injection wells, 20 percent is managed in evaporation ponds, and the remaining 20 percent goes into surface waters under permits by the Colorado Department of Public Health and Environment.
The injection of water through an underground injection control well requires certain casing and cementing, monthly reporting on materials and volumes injected and pressure tests to ensure the waste stays in the designated area.
The majority of evaporation pits sit in the Raton Basin in southern Colorado, and some water is used on roads for dust suppression if it does not meet the necessary parameters for disposal in streams or rivers that are drinking sources.
Companies reuse recycled water most if the surrounding area has high demand for it in other operations; otherwise they dispose of the production water.
In the average mixture, water and sand make up roughly 99.5 percent of the mix with the additional 0.5 percent consisting of chemicals that assist the flow of sand into the formation, according to COGA.
In addition to water and sand, COGA reports that hydraulic fracturing mixtures include gelling agents to make fluids thicker cross linkers to continue to thicken fluids, breakers to thin fluids to ensure production after time, surfactants to improve production and recovery, biocides to control bacteria, and additional additives to address other challenges.
Liquefied petroleum’s lower specific gravity decreases the volume necessary in operations by half which can reduce truck traffic by up to 90 percent and eliminates the need for post stimulation transport, Munro said.
GASFRAC’s system is primarily propane due to its presence as a natural, non-damaging hydrocarbon, he said.
The liquefied petroleum gas gel alternative involves injecting petroleum gel combined with sand under high pressure into the shale at similar ratios to hydraulic fracturing, he said.
GASFRAC has worked with liquefied petroleum gas technologies since the company became operational in 2008 and provides consultation to companies in Canada and rural Texas.
The company lauds liquefied petroleum gas gel as a “rare technology breakthrough in the oil and gas industry that can deliver both economic and environmental benefits for its producers.”
GASFRAC utilizes three major components in the use of the gel: storage tanks, a sand blender and specialized high pressure pumping units.
The company’s storage tanks involve a boost pump and nitrogen pressurization which feed the gel into the sand blender. Tanks are coated with a pressurized nitrogen blanket as a safety measure, Munro said.
Proppant, such as sand, is preloaded, purged and pressurized with the nitrogen to create a sand laden mix that stimulates the reservoir.
The process ensures the even distribution of sand in the mixture, which prevents it from settling in formations.
Munro said that the gel offers fewer restrictions than water in that more sand can be added to the mix to increase down-hole pressure and that the mixture can be altered to each well more efficiently.
As a formation friendly substance, the gel reduces the damage to surrounding environment as it occurs naturally down hole and is within a closed pressurized system. On average, more than 75 percent of the propane can be recovered and sold again compared to water operations, were recycling and reusing water can present a challenge, Munro said.
Additionally, he said the presence of hydrocarbons already in production eliminates the presence of biocides found in conventional fracking operations.
“It’s way more environmentally friendly and less likely to cause seismic events such as earthquakes,” he said.
Compared to the price of water recovery, he said the gel has a minimal cost after companies resell or repurpose recovered propane.
Additionally, the lower surface tension of liquefied petroleum gas gel can also produce a higher yield from wells when used properly, Munro said.
Due to the substance acting as an energized gel, petroleum gel helps to push fracking fluid in the well which has the potential to increase the natural gas yield in the wells, McLennen said.
“There is a pretty dramatic curve,” Munro said. “If used properly there can be a dramatic uplift in production.”
Munro said that they have seen the most dramatic increase in production at their Texas sites.
Additionally, McLennen said the higher availability of propane on site allows to easier access for oil and gas companies.
Another benefit of the gel comes through the use of butane which helps performance under high-temperature surface conditions, he said.
However, McLennen said the use of gel petroleum presents safety considerations which would require new expenditures and precautions to avoid injury.
“They are very expensive and because of the explosive properties of the substances used, they can be very dangerous,” said Encana’s Media Relations Manager Doug Hock.
Hock said that due to the gel’s relatively recent appearance in the oil and gas world, very few companies know about its definite benefits and disadvantages or have done research into its applications on individual formations.
“In speaking with our chief of completions, he tells me that completely waterless fracs are seldom done,” Hock said.
Alternatively, Hock said Encana has utilized nitrogen gas in its San Juan Basin operations in New Mexico which reduces, but does not fully eliminate, water use.
“The reason for using a nitrogen (fracture) is low reservoir pressure,” he said. “While it does reduce the amount of freshwater used, that’s not why it’s used.” Nitrogen, which makes up between 30 and 70 percent of the mixture with water, is added at the wellhead in a mixture with the water and pumped down hole. The nitrogen additive appears as foam similar to shaving cream, Hock said.
Both nitrogen and CO2 do not have the same volatile properties and risk of explosion, he said.
“The main problem with propane is that it is explosive, that’s been the big challenge with it,” he said. “Of course, we’re always looking for new ways to be efficient.”
Other options, such as non-flammable hexaflouropropane used in inhalers, stand as viable options to decrease water use in hydraulic fracturing operations. Hexaflouropropane solutions virtually eliminates the flammability risk at the surface and replaces water in the fracking process, McLennen said.
In order to ensure the safety of on-site employees, GASFRAC implemented remote control shut-offs, automatic shutdowns if propane leaks are detected and thermal monitors. In addition to these precautions, no physical workers are present on site, Munro said.
Thermal cameras are used to monitor all high-pressure lines while crews monitor pressure transducers throughout the system remotely from vans offsite, according to the company’s safety statement.
“We’re the safest operations in the world,” he said. “These are the safest operations I’ve ever observed during my time in the industry.”
However, the necessary safety precautions to monitor the highly explosive propane can provide high overhead costs that can deter companies from implementing the use of gel to replace water.
“It’s not something we are exploring here for several operational and effectiveness issues,” Noble Energy Corporate Communications Manager Steve Silvers said.
While many companies, such as Noble Energy and Halliburton, do not currently use liquefied petroleum gel technology, Munro said that the growing popularity of hydrocarbon technology will lead to more widespread use of the substance in the future.
“For us it’s a game-changing technology,” he said. “It allows us to recapture and reuse (the gas) effectively.”
