NEW SYSTEM OFFERS HOLISTIC APPROACH TO FRACK WATER TREATMENT
May 02, 2013
A wastewater treatment process long utilized in the food industry now is available to treat flowback and produced water from hydraulic fracturing. Established in 2002, Alpharetta, Georgia-based Ecologix Environmental Systems has provided wastewater treatment services to companies such as Tyson, Kellogg’s and Toyota as well as mining and metal plating industries.
The company has reached agreements to ship its wastewater treatment management system to oil and gas customers in Canada and Texas. These units are the third generation of systems geared towards the oil and gas industry – the company previously had sent protoypes into the field in Oklahoma and Texas’ Permian basin to learn the lessons of what and what not to do. These lessons include everything from how to maximize unit performance, improve manufacturing and make the units more user-friendly in terms of maintenance and ground operations. The company also sold a prototype unit to Halliburton Co. that reduced the turbidity level from 530 nephelometric turbidity unit (NTU) to just 3 NTU, a 176 fold improvement in water clarity.
When Ecologix CEO Eli Gruber looked at the oil and gas industry, he saw nothing had been done to address wastewater treatment in a way that made sense to him. Various companies had rushed in with black box ideas, but Gruber still saw a need for a water solution to correct the whole spectrum of contaminants. “Other companies who rushed in do one thing well, but they ignore five other things,” Gruber told Rigzone in a recent interview. “We attempt to take care of every step along the way to both clean and disinfected the water.”
Ecologix’s Integrated Treatment System (ITS) for hydraulic fracturing water treatment allows water to be treated near the well pad, allowing the storage and transportation costs of produced and flowback water to be eliminated. The ITS also eliminates the need for fresh water withdrawal, shortens hauling distances and reduces truck traffic and creates reusable water from waste, eliminating need for water disposal. The platform uses a basic wastewater treatment process, Dissolved Air Flotation (DAF), which uses targeted chemicals to precipitate oils and solids out of suspension and a physical mechanism to remove these solids from the water. In the DAF process, millions of tiny air bubbles force suspended solids and fats, oil and grease to flow to the surface, where they can be skimmed away. Through this process, over 99 percent of the sludge can be removed.
The ITS-900 consists of three main units:
- •to control chemical dosing
- •to mix the chemicals into the water
- •to perform the physical separation of solids
The ITS process is flexible, and can be adapted to meet the specific needs of the formation and driller preferences. The ITS platform is available in two sizes: one that can process 900 gallons per minute, or 31,000 barrels per day, and a fourth generation ITS that can process 500 gallons per minute, or 17,000 barrels per day. The fourth generation ITS has a lower processing rate, but it has a smaller footprint that combines equipment from two trailers into one. The company will limit production of the units to the smaller unit, noting that customers can always choose to utilize two ITS-500 units, if the volume of water justifies it, Gruber
noted. “However, the 17,000 barrels per day unit seems to be within the industry’s sweet spot for most fracking operations,” Gruber noted. The oil and gas industry’s increased use of hydraulic fracturing to explore for and produce unconventional oil and gas has made the treatment of produced and flowback water a top concern for the oil and gas industry, environmentalists and the government.
Between one and five million gallons of water are used in the hydraulic fracturing of one well. The high volume of water used in this process has raised concerns about water resources used in agriculture or drinking water being diverted towards hydraulic fracturing instead, particularly in areas that have or are experiencing drought conditions. The impact on drinking water supplies due in part to the disposal of
flowback and produced water, which could contain organic chemicals, metals, salts and naturally occurring radionuclides, is another issue.
To deal with wastewater, oil and gas operators have either injected wastewater into disposal wells or hauled water away by truck. However, some studies have indicated that injecting hydraulic fracturing wastewater injection into disposal wells can trigger earthquakes. A recent study tied a series of earthquakes in central Oklahoma to the injection of wastewater deep underground. Additionally, high salt levels in water can reduce the number and types of organisms found at a site, impacting the entire ecosystem, according to a recent study Australian and European researchers. The heavy traffic of trucks hauling wastewater and other materials related to shale exploration and production has resulted in wear and tear on roads around the country. Almost 1,200 loaded trucks are needed to bring one gas well into production, over 350 are required each year for maintaining a gas well, and nearly 1,000 are needed every five years to refracture a well, according to the March 2013 Eagle Ford Shale Task Report. In many places, the existing roads are not equipped to handle the weight and volume of this traffic. Gruber sees his company’s technology as a way to keep both environmentalists and the oil and gas industry happy.
“What appears to be clean may not be clean,” Gruber commented, noting that the oil and gas industry’s previous attempts to clean water fell short. By using a short-cut approach, only 20 percent of suspended solids are removed from water, and without a chemical solution, only larger suspended solids will be removed, leaving small suspended particles behind. These smaller suspended solids, called colloids, have very large surface area that add friction to the gelling agents and friction reducers, negatively affecting the viscosity of the fluid from carrying the proppant sand further distances in the water and keep the hydraulic fractures open, impacting the efficacy
of a frack job. Arguments have been made by some in the oil and gas industry that salt must be completely removed from the water to make it suitable for reuse in hydraulic fracturing, Gruber stated that this is simply not the
Gruber cited a recent study conducted by Halliburton and XTO Energy and that the level of salt in water does not impact the quality of a hydraulic fracturing job as long as the total suspended solids have been removed. This finding means that oil and gas companies do not have to remove water from aquifers, meaning this water can be saved for agriculture or other purposes. In the study, Halliburton and XTO found that produced water with total dissolved solids levels as high as 285,000 milligrams per liter, or 28.5 percent salinity, was shown to generate proper cross-linked rheology for hydraulic fracturing in line with wells that were fracturing with just 20,000 parts per million, or 2 percent salinity.
The study results, which were published by the Society of Petroleum Engineers earlier this year, came from a test of seven wells in New Mexico’s Delaware Basin. In the field study, a mixture of common drilling chemicals, such as Carboxymethyl Hydroxypropyl Guar Gum, a zirconium-based cross linker, sodium chlorite breakers and non-emulsified surfactants were blended with 100 percent treated produced water to generate a frac fluid that performed as well as that expected from a fluid based on fresh water.
“The study shows that brine water possesses all the characteristics required for effective fracking: easy preparation, rapid hydration, low fluid loss, good proppant transport capacity, low pipe friction, and effective recovery from the reservoir,” said Gruber in a recent white paper in regards to the Halliburton- XTO study. “Unlike fresh water, salt water does not restrict oil flow because of an osmotic imbalance that results in clay swelling.”
That study also indicated that by using produced water for hydraulic fracturing can help reduce approximately 1,400 truckloads from the roads, and all but eliminate the use of disposal wells. The study delivered $70,000 to $100,000 cost savings per well.
“Removing the suspended solids is the key,” Gruber commented. “If you take shortcuts, you compromise the quality of the hydraulic fracturing job.”
For this reason, 100 percent brine water can be used for hydraulic fracturing, so long as the suspended solids are removed completely.