State investigating source of gas at De Beque home
Natural gas monitors are being made available to residents in De Beque after the discovery at a home of high levels of gas that may have originated from shallow underground geological formations.
The Colorado Oil and Gas Conservation Commission is investigating the incident, involving a home on Minter Avenue, and whether it may be related to oil and gas development or possible natural migration of what’s sometimes called stray gas to the surface.
Investigators also have found gas in and around an abandoned water well dating back before the 1950s in an alley within two blocks of the home, and are in the process of permanently plugging that well.
The West Slope Colorado Oil and Gas Association, and specifically Chevron, Laramie Energy and Caerus Oil and Gas, have made free monitors available through the De Beque Fire Protection District. Residents in about half of the town’s more than 200 homes have taken advantage of that offer so far. Fire Chief Mike Harvey encourages other homeowners to do the same and said monitors are available to interested residents outside town limits as well.
There have been no reports of high gas levels at additional homes. West Slope COGA has offered to pay for the affected home’s occupants to stay elsewhere while the investigation continues, but the family has chosen to remain at home. Stuart Ellsworth, engineering manager for the commission, told the commission Monday that a ventilation system is operating at the home and it’s his understanding that gas levels in the home remain lower than combustible amounts as long as the system remains active.
While state officials indicated the gas in the home initially was at explosive levels, Harvey said the high methane levels were detected outside the home, near the foundation, rather than inside.
Ellsworth said Xcel Energy found the gas while doing a driving survey around May 15 for possible leaks in the town. He said Xcel noticed a leak that appeared to be coming from a crawlspace in the house. He said his understanding is that the only other types of leaks it found in the De Beque survey were from meters, which Xcel repaired.
Samples showed the gas found at the Minter Avenue home contained no mercaptan, the odorant added to natural gas before it’s delivered to consumers by retail utilities such as Xcel. Gas composition analysis indicates the gas at the home is different from gas flowing in nearby pipelines, and results of tests based on isotope analysis are pending to verify that, said Dave Andrews, an engineering supervisor for the commission.
Initial tests indicate the gas at the home and in the well are thermogenic, meaning the gas was formed under geological heat and pressure underground, rather than emanating from surface sources such as landfills or bogs.
State officials also have collected gas samples from five oil and gas wells within three miles of De Beque to compare them to the discovered gas. Andrews said no industry-operated wells are within three miles of De Beque. All five wells that were sampled are what the state calls orphaned wells, which are typically older, with the state left to deal with them because the owner or operator can’t be found or is unable or unwilling to plug them.
Drilling in the De Beque area goes back to around 1900, Andrews said, and the commission has been plugging old wells in that area for the last six years.
“We still have some work to do around the town,” he said.
State officials are also investigating whether the town’s location atop what’s called the De Beque anticline geological formation could be a factor behind the recently discovered gas. The presence of the anticline means that gas-bearing Wasatch sandstone formation lies not far below the surface, and the gas-rich Mesaverde formation lies just below the Wasatch, just 700 feet underground.
The water well that’s being plugged by the state was only 26 feet deep, but crews drilled deeper and found gas in sandstone 40 or 50 feet underground, Ellsworth said.
Harvey said investigators are leaning toward the possibility that the discovered gas is the result of a natural phenomenon.
“We’re going to be investigating some of the geological formations that are in and around De Beque to see if that’s a contributing factor,” he said.
He said issues involving shallow gas are nothing new for De Beque.
“The old-timers talk about the methane coming up through the water wells,” he said.
He said he’s never heard of any home explosions occurring in De Beque “related to anything like this.”
In April, two people died in a home explosion in Firestone that investigators blamed on an abandoned flowline from a nearby oil and gas well that was severed near the home.
Asked about the public’s mindset in De Beque following the incident there, Harvey said, “People who live in De Beque, they’re used to working in the gas and oil fields and they understand.”
David Ludlam, executive director of West Slope COGA, said getting people gas monitors is important regardless of the source of the discovered gas.
“I don’t know if it’s a geological anomaly, but because of the (anticline) formation there we think it makes sense for people to have monitors no matter what, even if there wasn’t any oil and gas drilling in the area,” he said.