From the oil fields in West Texas to the Barnett Shale in the Fort Worth basin, drilling activity in the Lone Star State leads the nation with 720 rigs, followed by Louisiana with 183, North Dakota with 132 and Oklahoma with 126. According to industry estimates, onshore drilling rigs reached 1,640 in August, with 640 drilling for oil and 1,000 drilling for natural gas.

Much of the oil and natural gas exploration involves drilling in “unconventional” sources such as shale formations that were formed by microscopic organisms that lived in ancient seas 143 to 65 million years ago. The U.S. Energy Information Administration estimates that by 2030, half of the natural gas produced in the U.S. will come from unconventional sources such as the Barnett shale with its more than 3,500 natural gas producing wells.

Horizontal drilling techniques and hydraulic fracturing methods used to unlock oil and gas from shale formations require significant water resources to fracture or stimulate rock around the wellbore so the oil or gas can flow. According to researchers at Texas A&M University, a horizontal well can use between 5 and 6 million gallons of water in its fracturing operations. And over the course of its life, a well may need to be fractured several times to keep the gas flowing, with each operation requiring larger volumes of water than the previous one.

Shale formations contain embedded salts that dissolve when injected with water. The fracturing flow-back water from the Barnett Shale, for example, contains as much as 100,000 parts per million (ppm) salt content compared to 33,000 ppm of salt in seawater. The U.S. Geological Survey (USGS) has estimated that Barnett shale gas wells can produce a median of 1,638 gallons of wastewater per thousand cubic feet of shale gas.

Typically, “produced” water is pumped to the surface for removal by vacuum trailers hauled by trucks to commercial saltwater disposal (SWD) wells for reinjection into a porous rock formation. An estimated 53,000 disposal wells exist in Texas, according to researchers at Texas A&M University. The U.S. Department of Energy has estimated that overall, more than 18 billion barrels of produced water is generated in the U.S. annually from onshore wells.

A single horizontal well will have more than 100 water-haulers servicing it during fracture stimulation. “These trucks need an economical protective lining that is resistant to saltwater and other less aggressive chemicals,” Tnemec coating consultant Lane Salvato explained. Viper Basting & Coating used Series 141 Epoxoline, a high-solids modified polyamine epoxy, for the lining of the haulers.

The tank interiors were prepared in accordance with SSPC-SP5/NACE No. 1 White Metal Blast Cleaning prior to being lined with Series 141 Epoxoline, which was spray-applied in a single coat of 14 to 18 mils. “Series 141 Epoxoline can be applied in a single coat and is a good niche between a standard polyamide epoxy and a highly cross-linked chemical resistant novolac,” Salvato noted. “Approximately 15 to 20 gallons of the coating are required per trailer, depending on its size.”

In August, a study group at the Massachusetts Institute of Technology (MIT) reported that “…the application of horizontal drilling and hydraulic fracturing technology to the shales has caused resource estimates to grow over a five-year period from a relatively minor 35 trillion cubic feet (Tcf) to a current estimate of 615 Tcf, with a range of 420-870 Tcf.”