With the uptick in hydraulic fracturing activity since the early 2000s, the Permian Basin has experienced a series of strange phenomena. One of the most bizarre incidents occurred in 2022, when an abandoned well in Crane County suddenly erupted like a geyser on New Year’s Day, spewing toxic wastewater nearly 100 feet into the air at a rate of just under 150,000 cubic feet per day for nearly two weeks. The Texas Railroad Commission (RRC), which regulates the oil and gas industry, has claimed that these wells are not its responsibility. Meanwhile, the exact origin of the phenomenon has remained a mystery. Until now that is.
Vamshi Karanam, Zhong Lu and Jin‐Woo Kim at Southern Methodist University recently released the findings of their investigation into the Crane County well blowout that definitively identifies the source of the problem: injected wastewater from fracking. The study titled “Investigation of Oil Well Blowouts Triggered by Wastewater Injection in the Permian Basin, USA” appeared in Geophysical Research Letters, a peer-reviewed journal published by the American Geophysical Union.
Oil and gas exploitation in the Permian Basin goes back over a century. For every barrel of oil recovered from a well, up to 10 barrels of “produced water” are also recovered. The preferred method of disposal for this wastewater is to inject it into depleted subterranean reservoirs like those of the Central Basin Platform (CBP), whose hydrocarbons were removed long ago. “While this is an economically viable approach,” state the authors, “the diffusion process may be disrupted due to the complex subsurface in the CBP, the presence of many aged wells, and an increase in injection volumes. This can lead to … groundwater contamination, increased fault slips, and the flow of injected water back into surface reservoirs via old and abandoned oil wells.” The study focused on the southern part of the CBP, specifically on Crane and Ward counties, within the Pecos River valley, where “the prevailing groundwater trend … is from north to south, toward the Pecos River.”
The authors used “high-resolution … satellite imagery … to visualize the surface changes during and after the well blowouts … [and] modeled the surface deformation … to estimate the source depth and geometry.” They also noticed that a “cluster of injection wells toward the NW of the study area contributed to most of the wastewater injection in the study area.” Given the proximity of these wells to the affected regions, the authors “obtained the well depths and injection volumes for these wells for further analysis” from the RRC database to correlate the deformation results with the wastewater injection activities. They then “calculated the cumulative deformation volumes by multiplying each pixel’s area by its corresponding cumulative uplift value,” summed these values for “all pixels within the study area” and then compared these “cumulative uplift volumes … to the cumulative injection volumes.” According to the authors, “The cumulative deformation volumes calculated by multiplying the pixel area with the cumulative uplift for each pixel strongly correlate with the cumulative wastewater volumes injected into the group of wells in the NW.”
“The time-series deformation results … offer a compelling insight into the dynamic subsurface processes in the region [which include] an uplift pattern extending linearly from the northwest to the southeast.” The authors point out that the deformation maps also reveal an “event between 02 January 2022 and 14 January 2022 … that produced a subsidence” of a little over an inch in 12 days. “The same is also evident in the time-series graph and stands in contrast to the general uplift trend observed in the region.” The location and timing of this subsidence align closely with the Crane County blowout, making it reasonable to assume –– based on the “spatial extent of the subsidence” and the “source geometry for the blowout” that a “wastewater aquifer in an over‐pressurized state may be responsible for the uplift trend.” Meanwhile, “the wastewater ejected at high pressures during the blowout also supports this inference,” along with “several instances of wastewater leakage [that] were reported in the region along the pathway.”
The results of the study “suggest that the injected wastewater leaked to shallower formations and propagated through subsurface flow paths. The water then accumulated in an aquifer several kilometers away resulting in excess pressure that was manifested as a surface uplift exceeding 40 cm [15 inches] in less than three years. The failure of aged oil well casings under this pressure led to wastewater blowouts over the aquifer and along the path. The sealing of the failed wells offered only a temporary solution, and the persistent pressurization in the subsurface poses an ongoing risk of future blowouts.” The authors stress that these findings “highlight the need for stricter regulations on wastewater injection practices and proper management of abandoned wells to prevent environmental risks such as well failures, surface subsidence, and potential groundwater contamination.”
Speaking at the Waters of West Texas conference last week in Pecos, James Harcourt, manager of the Groundwater Advisory Unit at the RRC, stated that the problem stems from “disposing of 90% of [produced] water in 6% of the available space.” After describing “pollution prevention” as the “most important thing” the RRC does, he urged the audience to imagine the subterranean disposal space in terms of “deep, medium, and shallow.” Concentrated injection into the deep space causes earthquakes, while too much injection into the shallow space causes blowouts. Harcourt assured the audience that the solution is simply to “stay medium” and “step out” the injection over a wider area. Time will tell. But with the eruption two weeks ago of yet another toxic geyser in Toyah — less than 30 miles from the spring-fed pool at Balmorhea — time may be running out.
Visit https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109435 to read the full report.
Trey Gerfers serves as general manager of the Presidio County Underground Water Conservation District. A San Antonio native, he has lived in Marfa since 2013 and can be reached at tgerfers@pcuwcd.org.