The thought of hydraulically fracturing a well without the use of water as the main pressure and proppant-delivery vehicle could someday be realized. New technologies and proven methodologies based on waterless fracture approaches are giving exploration and production companies and completion crews a water reduction option and in some cases, an option for more productive wells.
With oil and gas service companies working to finding an alternative to water-based hydraulic fracturing for water-constrained areas, the possibility of waterless fracking is becoming closer to reality.
Praxair and Expansion Energy LLC are two industry suppliers working to prove out the economic, production and water-reduction merits of waterless fracking systems. Efforts of each could eliminate the need for water at well sites and reduce the need to dispose of large volumes of fracturing wastewater.
Expansion Energy Debuts VRGE
Expansion Energy has developed VRGE, a unique, patented waterless fracturing and enhanced oil recovery technology that uses natural gas from nearby wells as the fracturing fluid. “In comparison to water-based fracturing, VRGE can lower total completion costs by as much as $2 million per well, is more resource-efficient and environmentally prudent, and can increase oil and gas production per well substantially,” says Jeremy Dockter, co-founder and managing director of Expansion Energy.
VRGE uses a dense, cryogenic non-liquid fluid phase of natural gas that Expansion Energy calls Metacritical (Meta-NG). Metacritical natural gas is synonymous with cold compressed natural gas (CCNG) that is used as the fracturing medium as well as part of a safe, proprietary proppant-carrying foam. Meta-NG is almost as dense as liquid. VRGE can use produced gas from a an oil or gas well as the main feedstock for the proppant dispersal system. Like injected water, the natural gas used by VRGE eventually resurfaces and can be sold to the market or used for further VRGE fracturing.
Extracted oil, natural gas and natural gas condensates evacuate the well bore the same way they exit a hydraulically fractured well, the company says. “Our objective was to develop a non-water fracturing and EOR process where the working fluid, which delivers the pressure and the proppant, would be a material that is widely available in oil and gas fields and is compatible with the hydrocarbon formation in terms of production, as opposed to water, which can actually restrict the flow of oil and gas by causing the shale to swell and increasing surface tension,” says Dockter. “In the case of VRGE, that working fluid is natural gas itself.”
How VRGE Works
Natural gas, potentially supplied from a nearby well, is converted to CCNG by an onsite cryogenic LNG or CCNG production plant and is then pumped to high pressure with a cryogenic natural gas pump. The high pressure CCNG is then vaporized with heat exchangers into high-pressure, compressed natural gas. The high-pressure, CNG is then blended with a high-pressure proppant-carrying slurry and foaming agent. The combined mixture is injected down-hole to the well bore as an “energized” foam, similar to CO2 and nitrogen foam fracturing fluids.
The high-pressure CNG and foam create, extends and holds open fissures in the underground formation while moving proppant into the fissures. Following the fracturing process, the pressure in the well bore is reduced, leaving the proppant to hold open the fissures, thus allowing for the flow of oil and natural gas like a traditionally water-fracked well.
The process is repeated for each stage of fracturing to be completed per well.
VRGE can also thermal shock a well.The CNG, foam and proppant can be injected down-hole at temperatures as low as -20 degrees Farehenheit because the slurry is not an actual liquid. The extreme temperatures can shock the warm formation, making it brittle and creating extending fissures.
“This LNG plant produces the cryogenic working fluid that VRGE uses to carry pressure and proppant into the well bore to conduct the fracturing,” says Dockter. “Producing CCNG onsite is far less expensive than trucking in LNG from a remote LNG plant. Therefore, the VRGE process optimally produces and uses CCNG instead of LNG.”
The design of the system is also based on best practice safety concepts within the industry. “VRGE's safety protocols are compatible with existing oil and gas well safety protocols,” says Dockter.
The advantage of using VRGE or other waterless fracturing technologies is the plethora of environmental, safety, economic, performance and efficacies they offer, according to the New York-based firm. VRGE eliminates the need for transportation, treatment and disposal of flowback water and chemicals. It eliminates truck water deliveries and reduces the number of pressure pumping trucks and trailers typically needed during a traditional frack job. The reduced traffic helps improve highway safety, which Dockter recognized as a major concern in producing regions. “VRGE’s on-site LNG/CCNG plant allows capture and sale of associated gas instead of flaring, and can also be used to strip NGLs from the gas stream,” Dockter says.
VRGE also has economic advantages for oil and gas producers. The waterless fracturing technology reduces well costs when compared to water-based fracturing by eliminating the cost for water consumption and transportation. It reduces the need for new disposal wells and according to Dockter, “substantially reduces costs for chemical and fluid additives and biocides.”
Like other energized foam-based fracturing systems, VRGE well performance can exceed typical well production rates by 1.5 times or more. The system may also produce shallower decline curves. The technology can be used in fracturing new wells, recompletions, lifting and even for enhanced oil recovery.
VRGE has not been deployed yet, but Dockter says the company plans on getting VRGE into producing fields by 2015 and has strategic partnering discussions underway with several large fracturing services companies considering licensing VRGE before offering it to their producer clients. Forming a new energy services firm able to deploy the VRGE system is also an option, Dockter says.
“Our vision is that VRGE will be a transformational technology for the oil and gas industry—not just an incremental improvement—which brings many benefits to producers, but without requiring drastic changes in the way producers operate,” says Dockter.
Praxair Utilizes CO2
Unlike Expansion Energy’s waterless technology, Praxair’s DryFrac waterless fracking technology replaces water with liquid carbon dioxide to fracture new wells and for enhanced oil recovery.
A blender mixes carbon dioxide and proppant together, the mixture is then pumped at high pressure through frack pumps.
“Our technology increases the conventional water blender with a blender that mixes pure carbon dioxide with the sand in precise concentrations necessary for fracturing,” says Mark Weise, business development director of oil and gas services for Praxair.
According to Weise, the DryFrac waterless technology is exciting for the industry because, “It provides a practical means to use a dry fracturing fluid.”
“It maximizes the productivity of the well and it will improve the sustainability of the offering because you don’t need to source the water and you don’t have to worry about processing the frack water that flows back,” says Weise. “From reliability and a safety point of view, carbon dioxide is a non-flammable gas and therefore it eliminates some of those safety hazards that might be associated with other types of technologies that eliminate water from the fracturing process.”
Praxair conceptualized the idea a few years ago, and has since worked to build the equipment and run it through a pilot testing phase before finally proving it down hole with the carbon dioxide and sand mixtures. The equipment controls were the main components needed to make the process a reality, Weise says.
Unlike Expansion Energy’s VRGE approach, Praxair’s DryFrac technology is being used in the field, however, the technology has not been used in the Bakken yet.
“It’s certainly an area that everybody has their eyes on,” Weise says. “Right now, we’ve found a reception where people have been looking at being concerned with the water sensitive oil formations out there. The Bakken, I think, would meet those criteria as well.”
Author: Emily Aasand
Staff Writer, The Bakken magazine
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