RELEASES OF GAS
Some of the largest air emissions in the oil and gas industry occur as natural gas wells that have been fractured are prepared for production.
During a stage of well completion known as "flowback," fracturing fluids, water and reservoir gas come to the surface at a high velocity and volume. This mixture includes a high volume of VOCs (volatile organic compounds) and methane, along with toxins such as benzene, ethybenzene and n-hexane. The typical flowback process lasts from three to 10 days.
Hydrocarbons are naturally occurring organic compounds that can occur as gases, liquids or solids. The most common hydrocarbons are natural gas, oil and coal.
VOCs are hydrocarbon compounds that are generally highly toxic, often carcinogenic, and easily absorbed into water (some examples are propane, benzene, toluene, ethylbenzene and xylene.)
Since VOCs, both manmade and naturally-occurring are frequently used in drilling operations, there is a great deal of concern about the potential for ground and drinking water contamination resulting from their use.
Life and sickness in the gas patch
"We were very against it," Dee Hoffmeister from Dry Hollow, Colorado recalled. They watched a neighbor deal with another gas drilling company and ultimately move away to escape the smells, noise and other problems.
Ultimately, Hoffmeister was convinced that they had no choice but to lease their rights. Drilling started six years ago. Her grandson was diagnosed with asthma shortly afterward and Hoffmeister has suffered from recurring illness with no diagnosis.
The worst was a big gray cloud enveloping their house. "I suppose it was all the trucks idling," Hoffmeister said. Whatever the source, when she entered the house she started getting dizzy and passed out.
Her family drove her to her daughter's house in West Glenwood, where she stayed for eight months. Any time she back to Dry Hollow, she'd fall ill immediately, feeling dizzy, light-headed and weak, with occasional stomach upset.
In 2011, a workover rig was unexpectedly erected near her home. Powerful fumes drifted from the rig to her home, enveloping her, her daughter and grandson.
"The first morning the smells hit, they just started gasping for air," Hoffmeister recalled. They shut down the air conditioning to keep the smells out, but that had little effect.
Nowadays, Hoffmeister's pains tend to migrate from one part of her body to another, and her hands and feet itch and burn much of the time. She continues to spend a lot of time inside, unable to water or work in her garden when the odors become unbearable. Her grandson continues to suffer asthma attacks if the fumes become intense.
Dee Hoffmeister is just one of the many suffering from the gases produced by oil and gas drilling. The industry has long discounted claims by those living near gas wells that the drilling-related activities were making them sick.
Hydrogen sulfide gas
Hydrogen sulfide gas (H2S) develops naturally in conjunction with crude oil and natural gas. It's produced when certain bacteria consume sulfur-bearing organic matter. Whether there's H2S depends mainly upon the environment when the rock formations were deposited.
When there's hydrogen sulfide in natural gas formations, it's called "sour." If there's no hydrogen sulfide, it's called "sweet."
There are areas in Colorado, like the Western Slope, where the gas is "sour" and contains a significant amount of H2S. In low concentrations it smells like rotten eggs. There may be less hydrogen sulfide on the Front Range in theNiobrara formation.
Hydrogen sulfide a significant safety issue
According to the U.S. Centers for Disease Control, hydrogen sulfide is a hazardous and toxic gas that, when inhaled, can cause severe respiratory distress, headaches, loss of motor control and memory and other human malfunctions.
Concentrations lower than 10 parts per million (ppm) are considered relatively harmless. At 100 ppm or more, it can paralyze the olfactory nerve and cause a loss of the sense of smell. Exposure at increasing concentrations can cause nausea and vomiting, difficulty breathing, shock, convulsions and death in the most severe cases.
Hydrogen sulfide detectors and warning horns on the drilling rig warn of danger. Flags or windsocks show the drilling crew how to get out of the way.
"Deaths due to breathing in large amounts of hydrogen sulfide have been reported in a variety of different work settings, including ... oil and gas well drilling sites," stated the CDC's Agency for Toxic Substances and Disease Registry. One whiff of a strong concentration can be fatal.
In September 2011, a COGCC commissioner said he is concerned the agency overlooked reports that a toxic gas was being encountered at near-fatal levels on Western Slope drilling sites. In a presentation in November 2011, Stuart Ellsworth, engineering manager for COGCC, said hydrogen sulfide gas has been reported at 312 of Noble's 353 producing wells in the area.
In most instances, the gas was at concentrations lower than 10 parts per million (ppm). But in four incidents, Ellsworth reported, Noble encountered hydrogen sulfide gas at concentrations of 100, 170, 200 and 450 ppm. Exposure at those levels can cause loss of the sense of smell, breathing difficulties, eye irritation and, at around 500-700 ppm, death.
In December 2011, Noble Energy reported dangerous levels of hydrogen sulfide gas have been measured at least once at dozens of its wells not just in Garfield County, but Weld County as well. The company says 21 of its wells in the Piceance Basin have had levels at or above 100 parts per million on at least one occasion, as have 32 wells in the Grover oil and gas field in Weld County.
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