Mar 2011
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Source: Oilweek Magazine
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Calming the waters
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As the number of horizontal multistage fracturing projects grows exponentially, the industry meets public concern with new fluid handling
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by Graham Chandler
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The newest technological revolution in the oil and gas industry is horizontal multi-fraccing. Directly or indirectly, the technique has been responsible for US$4 gas, a century-long supply for U.S. consumers, reduced production costs in the oilsands, promises of a clean fuel for everything from electricity generation to powering nationwide truck fleets-the list goes on.
But it has its challenges. Water concerns-flowback water, produced water and aquifer protection among them-head the list.
Horizontal multi-fraccing hasn´t been around that long. According to the Railroad Commission of Texas-that state´s counterpart to Alberta´s Energy Resources Conservation Board-the first successful modern slickwater (light sand) frac happened just 14 years ago in the Barnett Shale. The Barnett has been producing gas ever since-and using a lot of water in the process.
"Some slickwater jobs use staggering amounts of water," says Brad Rieb, region technical manager at BJ Services Company Canada. "You can have wells with 15 frac stages per horizontal wellbore and they can take anywhere from 2,000-3,000 cubic metres per stage of water. It is a big business."
With pumping services and capacity on the rise, those figures leverage into some pretty hefty water needs. Two of Canada´s largest frac contractors, Calfrac Well Services Ltd. and Trican Well Service Ltd., have announced plans to increase their pumping capacities by 37 per cent and 36 per cent, respectively, for 2011. It´s the trend in the industry.
Where does that leave water management responsibility? In the Barnett, the Texas Water Development Board commissioned a study to look at future water needs. It projected water demand increases for shale development of up to 13 per cent by 2025, prompting new recycling projects.
In Canada, where multistage fraccing got a later start, the majority of frac water comes from fresh sources.
"It seems to vary but overwhelmingly it is still fresh water," says Rieb, "which we are very lucky to have in western Canada." It´s usually potable water purchased from municipalities. "Probably well over nine jobs out of 10 are what I would consider fresh water."
But as requirements grow, some municipalities shun new sales of their potable water.
"Southeastern Saskatchewan is probably seeing the highest amount of pressure to convert to produced water systems, because activity is simply so high there," says Rieb. Less use of fresh water means more reuse and recycling of produced water.
At first glance, using produced water makes more sense-it´s right there on site. But it´s not so simple.
"Produced water is a witch´s brew of all sorts of things," says Rieb. "The broad bucket of produced water includes flowback water from the previous treatment, which is frac water of varying chemistry. Interspersed with that is actual formation water."
The ratio of produced water to flowback constantly changes, Rieb adds. "And often the water that´s gathered in facilities, if they are brand new, will have a high level of iron because it is new iron that it´s being stored in-new pumping equipment, new tubular, new treaters and new separators. It´s really a complex blend of water qualities, types and chemistries."
Operators in the Barnett Shales have now begun using special mobile recycling units. One of those approved by the Railroad Commission is a system designed by Fountain Quail Water Management that recycles 80 per cent of flowback water. On-site distillation units apply heat to separate out and concentrate the salt water, which is sent to a disposal well, and the remaining distilled water is reused for fraccing. On-site produced natural gas is used to fire the distilling units.
Ratios have proven up well: as of April 2010, 9.3 million barrels of reusable water had been processed out of about 11.9 million barrels of returned frac water.
But there´s more to cleaning up produced and backflow water. Produced waters emerge from the well with several foreign contaminants that need to be eliminated before disposal or reuse. Friction reducers to reduce power needs for pumping, biocides to inhibit organic growth that can sour a reservoir, surfactants to keep the sand suspended-all may be present. Devising the right cocktail to counteract these is a moving target.
"It´s like a broad-spectrum antibiotic-if you´re too narrow you exclude a lot of stuff, if you are too broad then it means it might not work right," says Rieb. "So we have to use the right chemistry to hopefully capture the lion´s share of these water qualities."
Attention is not only on disposal of produced waters. As the shale industry advances in regions of North America, Poland, Germany and France, populations are unfamiliar with multistage fraccing. Around Quebec´s Utica shales and the eastern United States´ Marcellus shales, fears are prominent that the technique can foul local water aquifers. It has led to delays by companies such as Questerre Energy Corporation, which has announced a hold on new Quebec operations until the provincial government completes a report into the environmental effects of shale gas production and introduces new legislation.
Such concerns are wholly understandable and place pressure on operators keen to develop. "Of course, the concern is justified in the sense that everything related to our quality of life and the environment is justified and deserves our attention," says Rieb. "By that I mean it can´t be brushed under the carpet."
But the industry feels that the possibility of aquifer contamination through multistage hydraulic fracturing is a remote one. "I´m sure in the past 50 years it has happened," says Rieb.
However, he believes the science of building wellbore construction has never been better than it is today. "Drilling the well, the mud quality, the science behind cementing the well, ensuring adequate and robust cement bonds, the testing of those bonds and the science of understanding what these hydraulic fractures do in the formation-the science and the knowledge behind it has never been higher."
Moreover, he adds, hydraulic fracturing happens far below aquifer levels. "On top of all this, our diagnostic tools monitoring these fractures [such as microseismic] are so sophisticated [that] we can say whether these fractures are growing out of zone or not-we know their dimensions."
Trican Well Service agrees. "The critical factors in protecting the aquifer are proper drilling and cementing practices-zonal isolation," says David Browne, Trican´s corporate director of technology. "Our frac fluids should never come into contact with aquifers because of physical distance and proper isolation of the aquifer."
Trican´s EcoClean products are formulated to be non-toxic, biodegradable and non-bioaccumulating, protecting the environment and handlers in case of surface spill. Browne says these products pass Microtox toxicity testing-meaning safe for human consumption-and so would not harm an aquifer even if there were communication between the product and the water.
"Whichever fluid the producers choose to use, whether our EcoClean line or any of our fluid products, the risk of aquifer contamination is virtually nil," says Browne.
As with BJ Services´ Viking PW (produced water) system, Trican now uses a friction reducer that permits reuse of produced water, even when it contains high levels of salt.
"It enables producers to use produced water instead of fresh water," says Browne. He is speaking of Trican´s FR-8 and FR-9 salt-tolerant friction reducers, which have been designed for use in water-based fracturing fluids and specifically for brines with a high salt concentration. In addition, FR-9 passes the Microtox test, "making it among the most environmentally friendly friction reducers available," says Browne.
Trican employs other products to make the fraccing process more efficient and environmentally sound. One is called FlowRider.
"It´s a proppant transport modifier that significantly improves proppant distribution and regains permeability in vertical and horizontal wells," says Browne. "FlowRider enables proppant transport in slickwater frac fluid without the use of viscosifiers."
Another product specifically designed to reduce environmental impact is Trican´s EcoClean line. The EcoClean-GSW in particular is a high-performance slickwater fraccing fluid designed to eliminate contamination risks to geological formations, aquifers and product handlers, says Browne.
What are the chemicals used, then? They tend to remain an industrial secret, which prompts some to allege there´s a coverup. Rieb says no.
"That´s a conspiracy," he says. Instead, he chalks it up to the business competition factor. "Our industry is fiercely competitive," he says. "Intellectual property has to be guarded. There is a lot of litigation, et cetera, so if you develop a system that is unique but not patentable, you have to protect that."
That said, Rieb provides the latest in industry research efforts.
"They are quickly trying to adapt chemistry that has historically been used in the food business," he says. "For example, in the food business there is a lot of emphasis on the handling of bacteria-operational procedures and chemical procedures. Biocide, for example, in our industry has been a challenge in that we need to treat waters-produced waters, flowback waters, stagnant waters, stored waters-because they pick up organic material and bugs start to form."
He says you can´t dump those down a reservoir because you´ll sour it, so you have to use biocides. "The problem with biocides is they kill stuff," he says. "And they are very good at killing bacteria. If that water is not disposed of properly, you can kill fish, deer, human beings who come into contact. The food industry has products that are edible, for example, and we are now examining food-grade bacteria-control products. But you can´t just change things overnight. It has to be studied and researched."
Going forward, "there´s no question that it´s the movement towards completely environmentally compliant fraccing systems," predicts Rieb. "It will get better, the public and us want it that way. You will see significant advances in chemistry and water reuse."
Still, the issue of protecting potable water sources continues to grow and spread, he says, presenting cascading challenges for the industry. "We are now seeing areas where the municipalities are saying, ‘We don´t want to sell you the water we want to drink.´ Kindersley, Saskatchewan, is an example, and you will see the same thing coming in northeastern British Columbia."
Rieb adds, "The science of water rehabilitation is definitely coming to the forefront."
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