"A subsidiary of Nabors Industries Ltd. pumped a mixture of chemicals identified only as “EXP- F0173-11” into a half-dozen oil wells in rural Karnes County, Texas, in July. Few people outside Nabors, the largest onshore drilling contractor by revenue, know exactly what’s in that blend. This much is clear: One ingredient, an unidentified solvent, can cause damage to the kidney and liver, according to safety information about the product that Michigan state regulators have on file."
"A year-old Texas law that requires drillers to disclose chemicals they pump underground during hydraulic fracturing, or “fracking,” was powerless to compel transparency for EXP- F0173-11. The solvent and several other ingredients in the product are considered a trade secret by Superior Well Services, the Nabors subsidiary. That means they’re exempt from disclosure.
Drilling companies in Texas, the biggest oil-and-natural gas producing state, claimed similar exemptions about 19,000 times this year through August, according to their chemical- disclosure reports. Data from the documents were compiled by Pivot Upstream Group, a Houston-based firm that studies the energy industry, and analyzed by Bloomberg News. Nationwide, companies withheld one out of every five chemicals they used in fracking, a separate examination of a broader database shows."