Caldwell County TX: 13 Wells W. Hydrogen Sulfide Readings @ 300 ppm; 100 ppm "Immediately Dangerous To Human Health"

The first readings Abigail Edgar took of hydrogen sulfide and methane at oilfields in Caldwell County in 2021 were so high that she thought her equipment was malfunctioning. “It was off the scales. Methane was off the scales and hydrogen sulfide was off the scales,” said Edgar, a master’s student in geography at Texas State University. “The monitor would immediately start beeping when I crossed the property line.”

Edgar was recording dangerous levels of hydrogen sulfide at wells on private property in Caldwell County, 30 miles southeast of Austin. Hydrogen sulfide is a toxic and highly flammable gas often found in oil and gas formations. During the course of her research, the gas was so potent at three separate wells that Edgar’s respirator did not provide enough protection and she had to leave for her safety. Edgar teamed up with University of Cincinnati environmental scientist Amy Townsend-Small, an expert on methane, to take another round of measurements in 2023. They found the wells were directly releasing gas—including hydrogen sulfide (H₂S) and methane—into the atmosphere in a process called venting. Some of the wells venting gas were alongside public roads. Others were next to backyards and driveways.

In a paper published in Environmental Research Communications last week, Edgar, Townsend-Small and other authors at Texas State University and the University of Maryland report H₂S readings at 46 wells around Caldwell County. Hydrogen sulfide concentrations at 13 of the wells were at least 300 parts per million (ppm)—the maximum reading on the measuring device. Eight other sites had readings over 100 ppm. Exposure to 100 ppm of H₂S is immediately dangerous to life or health, according to the National Institute for Occupational Safety and Health. The study warns these H₂S levels are a hazard for people living and working in the area.

EDIT

The researchers selected 46 wells to study. The oldest had been drilled in the 1930s, but most were drilled in the 1960s through 1980s. All the wells are considered marginal, with less than 15 barrels of oil production a day. (In contrast, fracked wells in Texas can produce thousands of barrels a day.) The team took direct measurements from the wellhead using a Bascom-Turner Gas Rover and an Indaco Hi-Flow Sampler. Hydrogen sulfide was measured over a five-minute period. The methane emissions measured at the wells were similar to previous studies of marginal oil wells. Hydrogen sulfide concentrations ranged from zero parts per million to at least 300 parts per million, the maximum reading on the Gas Rover. Hydrogen sulfide can be immediately lethal at concentrations over 700 ppm. Exposure to more than 500 ppm will cause people to collapse within five minutes. An oilfield worker and his wife were killed by H₂S exposure in Odessa in 2019.

EDIT

https://insideclimatenews.org/news/20092024/central-texas-oilfield-high-levels-of-hydrogen-sulfide/