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Hydraulic fracturing: an evolving scene New techniques tackle concerns about environmental contamination, water usage and waste disposal while reducing production costs Alan Bailey Petroleum News
By first creating a glut of cheap natural gas and then upping oil production to a point where U.S. output is set to surpass the country’s imports, horizontal drilling and hydraulic fracturing techniques in shale hydrocarbon resources have up-ended the U.S. energy scene. But, while shale oil and gas enthusiasts have lauded the positive economic impacts of the new technology, others have raised concerns about the potential environmental impacts of widespread drilling, with the use of chemicals and huge quantities of water for “fracking” operations, and the possible contamination of groundwater through underground fractures.
In a talk to the Resource Development Council’s annual conference on Nov. 20, Michael Watts, director of fracture stimulation affairs for Halliburton, discussed some of the controversies surrounding hydraulic fracturing and some of the emerging techniques for minimizing environmental impacts and improving operational efficiency.
Lack of understanding Saying that many people’s fears about fracking stem from a lack of understanding of the science involved in the technique, Watts argued for action based on objective science, rather than on emotion, and for the promotion of positive messages about the benefits to the United States of shale oil and gas. In fact, the U.S. oil industry has been using hydraulic fracturing for many years, with the first use of the technique dating back to 1949, he said.
A modern shale oil or gas development involves the drilling of horizontal wells deep underground and then using pressurized water to fracture hydrocarbon-bearing rocks, so that oil or gas can flow relatively easily into well bores. Sand injected with the water holds the fractures open after the fracking operation is completed, while small quantities of chemicals in the fluid perform functions such as killing micro-organisms that can clog the fractures.
Distant from aquifers But the underground fracking operations take place far below near-surface aquifers, Watts said. In fact, a micro-seismic technique, involving the recording of sound from a fracking operation, enables the tracing of the locations of generated fractures — in the Barnett shale in Texas, for example, the shallowest fractures are many thousands of feet below the deepest aquifers, Watts said.
And a national registry called FracFocus now enables members of the public to obtain factual information about chemicals used in the fracturing, he said.
Well construction, which is subject to government regulation, involves multiple layers of cement and steel casing, to seal off the well bore that carries hydrocarbons from the producing rock formation to the surface, he said.
Holistic approach Watts said that Halliburton has been taking what he characterized as a holistic approach to developing new technologies for hydraulic fracturing fluids, taking into account the cost of the fluid, the effectiveness of the fluid in enhancing hydrocarbon production, and those aspects of the fluid that relate to health, safety and environmental protection. That holistic approach spans the entire gamut of water use, including water-use minimization through recycling, the use of benign water chemistry and the reduction of trucking operations in association with fluid transportation.
“I think that water management is going to be one of the biggest and most exciting things that we’ve got going on out there,” Watts said.
Benign fluids Halliburton now assesses all of its hydraulic fluids, honing in on individual components, ranking the components and eliminating some less desirable materials from the fluid chemistry, he explained. One outcome of this process has been the development of a new fluid that uses materials derived from the food industry and that are recognized as safe by the Food and Drug Administration, Watts said. Perhaps surprisingly, this new fluid has actually proved more effective than most other fluids in stimulating oil production, he said.
Another innovation involves the use of ultraviolet light to destroy bacteria in the hydraulic fluid, thus eliminating the need for chemical biocides. And an electrical process for coagulating fluids in water recovered from hydraulic fracturing enables the removal of just sufficient waste material from the water for the re-use of the water for further fracking operations. Water re-use in this way minimizes the amount of waste that needs to be disposed of while also reducing the demand on new freshwater supplies, Watts said.
Water salinity However, one of the challenges with water re-use is the high level of salinity often found in water produced from an oil well. To overcome this problem, Halliburton has developed and has been using a new system for dealing with the salinity and enabling the produced water to be used for fracking, Watts said.
“That’s a phenomenal step change,” he said. “Now we can take almost any kind of produced water and turn it into a usable frack fluid.”
Other innovations include the use of a new dry polymer blending system that incorporates gels into hydraulic fluid, eliminating the need for diesel fuel as a solvent and, by replacing fluid solvents by a dry powder, reducing the amount of trucking needed in support of a fracking operation.
And micro-seismic, the technology used to track fractures generated during fracking, is now used to create a 3-D image of the subsurface fracture pattern, as a means of evaluating the effectiveness of the fracking, as a development project progresses.
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