In West Texas, Water Is Scarce For Fracking
In West Texas, Water Is Scarce For Fracking, Expensive For Recycling, Cheap For Disposal Wells, And It Causes M5 Earthquakes.
Originally published on Forbes.com on January 26, 2023
While West Texas and New Mexico are wrestling with water-related problems, their oil production is booming along with larger magnitude earthquakes.
The Permian basin of West Texas and New Mexico is desert for the most part. The desert is called the Chihuahuan but is not a raw desert like the Sahara, but a desert due to on average 10 inches of rainfall per annum. Sparse, scrubby bushes like creosote and mesquite and a few big trees, like Cottonwoods exist along creekbeds that carry water. Water is scarce in the Permian. But not oil!
The Permian basin is the premier basin in the US for oil and gas production. It produces over 5.5 MMbpd (million barrels of oil per day), which is a big part of total US production approaching 12 MMbpd. Success out there has enabled Texas to remain the # 1 US state in crude oil production and last year has propelled New Mexico to # 2.
Water is scarce for fracking.
Fracking is key to success in the Permian basin where the shale technique starts with a horizontal well 1-2 miles long and pumps about 40 separate frac treatments along the well. The total water used is 20 million gallons, which would fill a football stadium to 40 feet above the grassed area. For use in fracking, freshwater has to come from cities or aquifers, or by recycling produced water.
Since a widespread drought hit the Southwest US about 30 years ago, freshwater is not cheap anymore. And if fracking water competes with aquifer water pumped up by ranchers, this spells trouble.
Expensive to recycle.
Water is produced up a well along with oil and gas. It’s too salty for use but it can be cleaned up. How much was produced water? Typically 1 – 5 barrels for each barrel of oil. The Permian basin produces 5 MMbopd which would translate to 5 – 25 MMbwpd (million barrels of water per day). Such enormous volumes of produced water have to be disposed of in some way or recycled.
The Marcellus shale, the queen of gas shales, has very few disposal wells by state government edict. Produced water is recycled or can also be trucked to Ohio where it’s poured into disposal wells.
Recycling of produced water has increased in the Permian in the last few years. This includes on-site clean-up and recycling of dirty water to use on the next fracking job. Or sending the dirty water for commercial cleanup, such as in a desalination plant.
Over 100 small-scale recycling facilities have been in use since 2015, and a handful of larger water recycling plants were planned to be commissioned by 2022.
Although cleanup/recycling methods are more expensive, they are gaining traction as oil and gas companies are feeling pressure to fix a problem that has caused two earthquakes of M5 (magnitude 5) that occurred one month apart at the end of 2022. This is not good for the industry’s image, even if the quakes caused limited damage to property.
Water is cheap for disposal wells.
In 2022, the combined Midland and Delaware sub-basins of the Permian produced 7 billion barrels which amount to 19 MMbwd. A large fraction of this was injected via disposal wells into deep geologic layers. This enormous volume of water was much greater than what Oklahoma produced in a year, 2015 when that state recorded 890 earthquakes of M > 3.
Looking at Culberson County, where most of the recent earthquakes have occurred (see Figure 1), injected volumes in 2020 were almost 0.7 MMbwpd.
Disposal of water causes M5 earthquakes.
In the Permian basin, earthquakes have increased in proportion to volumes of water injected in disposal wells. The correlation is strong, as it was in Oklahoma.
Warnings have appeared that the Permian basin might follow the earthquake trajectory of Oklahoma, which led to a 5.9M quake, Oklahoma’s largest ever, even after regulators had recognized the problem and reduced injections into disposal wells. Such delays fell in the range of 6-12 months.
So what has happened in the Permian? The Texas Railroad Commission (RRC) acted quickly after a 5.4M quake occurred in Culberson County on November 16, 2022 (Figure 1).
Injection volumes in the Culberson area had to be reduced by about 70% from early 2022 — and this was to be completed by mid-2023. This area has 78 disposal wells that are active. 19 of these are deep wells operated by Chevron and Coterra. The new injection limits had to be 745,000 bwpd in Chevron’s 10 wells, and 615,000 bwpd in Coterra’s 9 wells.
The clincher from RRC was how RRC would react if another M5 earthquake occurred in the area. If another M4.5 or larger quake occurs in the Culberson area, deep disposal wells close to the source of the quake will be shut in for two years. That would mean finding alternatives to dispose of the produced water: either trucking the water to disposal wells in other areas or cleanup/recycling the produced water onsite.
However, this would be just a mild hand slap, and would barely touch the huge profits being made out of the Permian basin.
Another M5 earthquake did occur just a month later.
Another big earthquake, M5.3, did occur just one month later, on December 16, 2022. This appeared to follow the Oklahoma pattern, but with an important difference. The second M5 quake occurred in a different area altogether – about 15 miles to the west of Midland, Texas (Figure 1).
The quake was widespread – and felt by people from Amarillo and Abilene in Texas to as far west as Carlsbad, New Mexico, according to USGS.
To understand this, RCC has identified enhanced seismic activity in certain areas called SRAs (Seismic Response Areas). According to R. J. DeSilva, Director of the Communications Division, Railroad Commission of Texas, the purpose is “to address and reduce seismicity and protect residents and the environment in different parts of West Texas. Each SRA is tailored to respective regions.”
The Northern Culberson-Reeves SRA is where the first M5 quake occurred on November 16, 2022.
The second M5 quake that occurred near Midland on December 16, 2022, is in a separate SRA called the Gardendale SRA. All deep injection wells have been suspended in the Gardendale SRA, said DeSilva.
The simplest explanation for the two M5 earthquakes is that they overlie two separate fault systems in the granite basement below. DeSilva says these basement-seated faults extend up into the sedimentary section where deep disposal wells are located. And this is how water pressure from disposal wells gets into basement faults that are critically stressed and prone to shift and create earthquakes.
Control of disposal wells in SRAs.
In general, the RRC in 2019 adopted guidelines for operating disposal wells in seismically active areas, which include volume and pressure limits and consideration of local geologic conditions. The RRC currently follows those guidelines.
Gardendale SRA: Deep disposal wells generally mean below the top of the Strawn Formation which lies under the Wolfcamp formation which has the deepest oil production intervals. All deep disposal wells have been suspended in the Gardendale SRA.
Northern Culberson-Reeves SRA: Deep disposal wells generally mean below the base of the Wolfcamp Formation, again the deepest productive formation. According to DeSilva, two deep wells in the SRA were already suspended in March 2022 following a 4.5 magnitude earthquake.
Also, after the November 16, 2022, earthquake the general guidance was specifically expanded to include this: “Should a future 4.5M+ event occur within the 9 km (roughly 5 miles) boundary identified on December 9, 2022, deep wells within the 9 km boundary will be shut in for 24-months from the date of the event.” So it’s not all wells within the SRA that would be suspended, but only wells within a 9km radial.