More than 25,000 plugged oil and gas wells across Texas are identified as being at critical risk of failure, a new analysis reveals. This finding indicates a hazard 50 times greater than previously reported for these so-called “zombie wells” — old wells where plugs fail, potentially releasing poisonous gas and toxic brine onto the surface.
A recent incident in Grandfalls highlighted the danger when a geyser of over 1.5 million gallons of toxic brine erupted from a plugged well in the parking lot of the First Baptist Church. Such blowouts pose immediate risks; poisonous gas released from these wells can be fatal, as seen in Odessa in 2019 when an oilfield worker and his wife died. The released water often contains hazardous substances like benzene and xylene, which are linked to cancer and can negatively impact human and animal hormonal and reproductive systems. When the source is injected wastewater, it can also contain synthetic chemicals, including PFAS, known as “forever chemicals.”
The Railroad Commission, the state agency overseeing oil and gas, lists approximately 1.2 million wells in Texas, with about 300,000 of them officially plugged. However, once a well is drilled, it requires permanent sealing, and the integrity of these seals is often compromised over time. Blake Scott, an oilfield-waste specialist, stated that the physics of cement, used to seal these wells, dictates that it will eventually fail, whether underground or on the surface. He remarked, “We’re betting that plug is going to last forever, when we know damn good and well it’s going to crack.” The American Petroleum Institute only issued its final plugging guidance in 2019, meaning many existing wells were sealed under older, less rigorous standards.
Further complicating the issue, old wells are frequently passed down to smaller, cash-poor operators or subsidiaries spun off by larger companies to declare bankruptcy, leaving little incentive or financial ability to maintain them properly. Hawk Dunlap, a well-control specialist, summarized the problem by saying, “No one likes to pay for a funeral.”
Pressure from below also contributes significantly to plug failures. Fracked wells generate roughly four times as much highly salty and chemical-laden “produced water” as they do oil, and this wastewater is typically injected back underground. Katie Smye, a geoscientist at the University of Texas at Austin, has calculated that some 60 billion barrels of wastewater have been injected into the Permian Basin, with half of that volume occurring since 2010. This immense volume of fluid, equivalent to nearly twice the capacity of Toledo Bend Lake, exerts considerable pressure, causing the ground in parts of West Texas to bulge upward. All this pressurized fluid seeks an exit, and an old well often provides the readiest path. A 2024 study by researchers at SMU tracked fluid that traveled approximately 12 miles underground before erupting from a plugged well.
Even without a dramatic blowout, failing plugs pose a serious risk through long-term seepage. Because these leaks occur underground, they can go undetected for years. A peer-reviewed study conducted in Pennsylvania found that plugged wells released benzene, a known carcinogen, at rates comparable to active wells. This ongoing leakage can lead to health risks for anyone living nearby, as gas and vapor containing substances like benzene, naturally radioactive radium, and arsenic can rise through the soil and foundations into homes. Children, who breathe roughly twice as much air per pound of body weight as adults, are particularly vulnerable to these exposures.
This new analysis, which formed the basis for a publicly available map, transforms scattered state records into a tool allowing individuals to check what lies beneath their own addresses. The model weighs several factors drawn from state records, including the age of the well and its plugs, construction quality data, and documented violations for injection wells. Most significantly, it considers the number of injection wells pumping wastewater within a mile of a plugged well into the same underground layers, as a higher number directly correlates to increased risk of plug failure. These findings were noted last month by the Houston Chronicle.
Prior reporting, including an article in the Barbed Wire and another in the Texas Observer, revealed a subdivision and elementary school south of Fort Worth built on an old “landfarm,” a site where drilling waste from the fracking boom had been spread. Parents at the school reported various health complaints, though testing commissioned by the developer later found the ground to be clean. Texas does not maintain public records on where this drilling waste was ultimately disposed, leading to the focus on the wells themselves.
With statewide officials in Austin identified as significant recipients of oil and gas industry funding, substantial changes in regulation are not anticipated. The creation of the Zombie Risk map offers Texans a way to independently assess the potential hazards beneath their properties.
