On March 3, 2015 9:00 am
By: Adam Larson, Staff Writer, Shale Media Group
Edited By: Mindy Gattner, Editor, Shale Media Group
In the shale oil and gas industry, the mentality of American producers has been backed with: drill, drill, drill – get as much hydrocarbon product out of the ground as possible. Producers move swiftly and with rational, calculated decisions. When it comes to fracturing shale, a few ingredients are integral: steel pipe, cement, drilling mud, proppants, pressure, and most importantly water.
In fact, the demands for fresh water used in hydraulic fracturing operations is placing pressure on water sources across regions involved in North American shale. Hydrogeologist David Yoxtheimer, Extension Associate, Penn State Marcellus Center for Outreach and Research, weighs in on the water discussion surrounding the Marcellus Shale.
“Typically it takes between four to five million gallons [about 100,000 barrels] to hydraulically fracture a horizontal well in the Marcellus,” expressed Yoxtheimer. “Laterals are getting longer, so a 10,000 foot long lateral could require ten million gallons—one million gallons per 1,000 feet.”
Along with this intense pressure for the demands of fresh water acquisition, water disposal demand has also increased. Well stimulation flowback water and produced water are generally considered waste byproducts of shale oil and gas production and increasingly present logistical factors for operators. Mainly, associated with these waste byproducts, compliance with local jurisdictions and environmental regulations hinder the disposal of water in the oilfield.
Notably, these water management problems are a bump in the road for the industry. Operators are using alternative methods of water management and killing two birds with one stone when it comes to fresh water acquisition and water disposal.
Recycling and reuse of flowback and produced water have been a common thread amongst Marcellus operators, reducing the total amount of fresh water used in their operations, and at the same time, reducing the volumes of flowback and produced water that have to be transported, treated, and disposed.
“Nearly 90% of flowback and produced fluids are being recycled in PA, the majority of which is being managed in the field with some treatment – often sediment removal via filtration or a scalant removal treatment prior to recycling,” said Yoxtheimer.
There are a few options when it comes time to manage flowback and produced water. Water management options include direct reuse without treatment – blending with fresh water for reuse in fracturing shale; on-site treatment and reuse; off-site treatment and reuse; and off-site treatment and disposal.
Direct reuse incurs minimal cost, but results in the potential for well plugging. On-site treatment reconditions the water at a temperate cost and has a decreased potential for well plugging. Off-site treatment and reuse incurs high transportation costs. Lastly, off-site treatment and disposal incurs high transportation and disposal costs.
“Reuse water is becoming a larger percentage of the water being used for fracturing; however, the volume used really depends on how much reuse water is available during fracturing operations compared to the total water demand,” noted Yoxtheimer. “It has been demonstrated that 100% reuse water can be used for fracturing as long as the chlorides and TDS level doesn’t interfere with the friction reducers, though generally it represents about a quarter of the water used in a hydraulic fracture job.”
One size does not fit all though, as water treatment technologies vary from shale play to shale play. Two broad classifications of technologies available for treatment and reuse of flowback and produced water are conventional treatment and advanced treatment technology. Both water technologies have environmental, economic, and energy upshots that are related to the quality of flowback and produced water.
Conventional treatment includes flocculation, coagulation, sedimentation, filtration, and lime softening
water treatment processes. These methods are effective in removing nondissolved constituents, such as total suspended solids, hardness compounds, and oil and grease. Simple filtration methods with nominal chemical inputs have lower energy, economic, and environmental effects.
In the Marcellus, Yoxtheimer underscored a popular water treatment technology. “Use of filter socks in the field is becoming common to remove sediment. Also, chemical precipitation has been commonly used for several years; however, some operators have backed off and are not as concerned with the potential for downhole scaling issues.”
Advanced treatment technologies are usually used to treat total dissolved solids (TDS). These advanced features include: reverse osmosis membranes, thermal distillation, evaporation, and crystallization processes. These advanced treatment technologies have proved to be less popular in the Marcellus, as producers aren’t too worried about TDS levels. “High TDS fluids can be desalinated but that is more energy intensive and therefore more costly, many producers are not as concerned about high TDS as they can dilute it with fresh water,” confirmed Yoxtheimer.
Closing the looped conversation, Alan Larson, a chemical engineer and water treatment expert, conveyed, “Produced water can be efficiently and effectively recycled by utilizing standard and innovative technologies. Many of these water technologies being used in the oil and gas industry have also been successfully applied in other industries for decades, assuring preservation of America’s abundant water resources.”
Shale Media Group (SMG) is the news, information, and education resource dedicated to the shale oil and gas industries by messaging across video, Internet, publications, events, and radio. For more, check out ShaleMediaGroup.com to access all platforms, including SMG’s latest news delivery system—Shale Energy Business Briefing (SEBB), an ad-free subscription based service, where subscribers receive a real-time, daily email, featuring concise, hard hitting shale news 7 days/week, 365 days/year. To sign up, go to sebb.us. In addition, join us on March 19th for our next Elite Energy Event at the Holiday Inn Express in Bentleyville, PA from 5-8pm. Adam Larson is a Staff Writer with Shale Media Group. Contact him at ALarson@ShaleMediaGroup.com.