More injections sought despite quakes

Investigation into wastewater well remains open

GREELEY — NGL Water Solutions DJ LLC, whose fracking-fluid disposal well was linked to earthquakes near the Greeley Airport late last spring, has asked to boost by 20 percent the amount of water it can inject underground, despite ongoing low-level quake activity captured by a new state monitoring program.

Since injections were temporarily suspended at the well in June, earthquakes have occurred every month at the 10,400-foot-deep well, according to documents obtained by BizWest through a Colorado Open Records Act request. At least one was nearly as large as the event that triggered a state investigation.

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Last summer, the Colorado Oil and Gas Conservation Commission briefly suspended activity after large quakes struck and a public outcry erupted. Injection activity was then allowed to resume in late July and the state launched an investigation into whether NGL had violated the terms of its disposal permit. The investigation remains open.

The permit, granted in the spring of 2013, allows the company to inject 10,000 gallons of wastewater daily. After the incidents last spring, however, the state required NGL to cut back the amount of water it injected. The amounts injected have been allowed to increase gradually and subsequent small quakes have been documented.

NGL declined to comment for this article.

Dozens of wells operating

In Northern Colorado, the drilling technique known as hydraulic fracturing generates enormous amounts of wastewater that oil companies typically inject thousands of feet underground. Fracking involves pumping millions of gallons of water mixed with sand and chemicals into a drilled hole to extract oil and gas from dense shale formations. Injection wells such as the one operated by NGL are designated specifically for wastewater and regulated by state authorities. Some 29 permitted disposal wells are operating in Weld County. NGL operated 11 of those wells as of July.

Earthquakes as large as 2.4 magnitude, just below the threshold of an earthquake with a magnitude of 2.5 that people can feel, continued to take place after NGL resumed injection activities last summer, according to documents reviewed by BizWest.

In an interview, state officials said they have taken precautions to reduce the likelihood of a felt earthquake, but stopped short of assuring that another one would not occur.

“I can’t assure (the public) that another felt earthquake won’t occur,” said Matt Lepore, director of the state oil commission. “Nor can I assure them that it will or won’t be related to an injection well.”

Monitoring creates more data

State officials do not know whether those earthquakes are linked to the injection well, but they continue to monitor injection and earthquake activity. They are using a scale typically used in geothermal energy development that can help them decide when NGL should adjust injected volumes of water depending on the size and frequency of tremors.

“We allowed them to begin injecting at a low rate,” Lepore said, “and then allowed them to increase that rate over time as we monitored the activity.”

Following a scientific test last July, the company used cement to seal off the bottom 400-foot portion of the well where wastewater poured into fissures in the rock that may have increased pressure close to the epicenter of the earthquakes, he said.

That action has helped decrease the number of tremors and the energy they release, said Stuart Ellsworth, engineering manager for the state oil commission. If an earthquake of 2.5 magnitude occurs within 2.5 miles of the well, the agency once again will suspend injection activity at the well.

State joins national quake group

Seeking to learn more about earthquakes related to well injection activities, the state oil commission has joined a 10-state working group to investigate whether wastewater disposal associated with fracking is linked to quakes. The working group formed after a rash of tremors happened in Oklahoma, where CU scientists also have found that an increase in earthquakes likely came from the injection of vast amounts of oil and gas wastewater underground.

Meanwhile, the state agency’s investigation into whether NGL violated the terms of its disposal permit continues without resolution six months after the first felt earthquake tied to the well occurred.

Lepore said the agency will conclude the probe “sooner rather than later,” but declined to discuss details.

Doug White, senior vice president of NGL declined to comment for this story. However, in a Sept. 3 email to a state oil commission staff member, White said, “We have not found evidence of violation of maximum injection pressures.”

In an Oct. 28 email, NGL told the state oil commission that it was “not aware of any abnormal seismic activity in the area” and asked the agency to increase its maximum daily injection rate to 12,000 barrels of wastewater per day.

The state oil commission has not approved that request, Lepore said.

Although NGL has cooperated with the state during the investigation, it also has pushed back against the regulators.

“NGL vigorously objects to the (state oil commission) establishing a daily injection rate limitation as part of the well-injection permit requirement,” White wrote in an Aug. 18 letter to the oil commission.

A history of quakes

Earthquakes associated with wastewater injection have happened in Colorado in the past. From 1963 to 1967, a series of earthquakes occurred when wastewater was disposed of in a 12,000-foot-deep well at the Rocky Mountain Arsenal, northeast of Denver. Wastewater injection from coal-bed methane production in the Raton Basin west of Trinidad also may have caused multiple earthquakes during the past few years, including a 5.3-magnitude temblor in August 2011.

Anne Sheehan, geophysics professor in the Department of Geological Sciences at CU-Boulder and fellow in the Cooperative Institute for Research in Environmental Science, confirmed that “very small earthquakes” have occurred east of Greeley since NGL resumed wastewater injection, “but not at a level that has caused us concern.”

CU-Boulder scientists are monitoring the Greeley earthquakes and are providing frequent updates to the state oil commission. If scientists see an increase in rate or size of the earthquakes, they will inform the state oil commission and NGL.

The state’s “plan to allow NGL to start injecting again at low rates and with close monitoring seems sensible,” she said. “They are paying close attention to this issue and taking it seriously.”

Earthquakes continue as injection well ramps up oil-and-gas wastewater disposal.

2012

Dec. 15: NGL Water Solutions DJ LLC drills and completes the oil and natural-gas wastewater injection well known as C4A next to the Greeley-Weld County Airport.

2013

March 22: The Colorado Oil and Gas Conservation Commission approves the well with a maximum volume of 10,000 barrels of wastewater per day.

April: Injection of wastewater begins.

2014

May 31: The first earthquake, with a magnitude of 3.2, occurs in the Greeley area and is felt in Boulder.

June 4: University of Colorado scientists complete setup of five earthquake monitors east of Greeley.

June 23: The second earthquake, with a magnitude of 2.6, occurs in the Greeley area. NGL suspends wastewater injection at C4A at the urging of the state oil commission.

July 10: A 2.3-magnitude earthquake occurs in the Greeley area.

July 19: NGL resumes wastewater injection at a rate of 5,000 barrels per day into C4A with approval from the state oil commission.

Aug. 7: NGL increases its rate of wastewater injection in the well to 7,500 barrels per day with approval from the state oil commission.

Aug. 13: Another earthquake, with a magnitude of approximately 2.4, occurs near C4A.

Sept. 3: A 1.8-magnitude earthquake occurs near C4A.

Oct. 3: With approval from the state oil commission, NGL further increases its rate of wastewater injection in the well to 9,500 barrels per day.

Oct. 12: Another earthquake of an unspecified magnitude occurs in the area.

Oct. 28: NGL says it is “not aware of any abnormal seismic activity in the area” and asks the state oil commission to increase its maximum daily injection rate to 12,000 barrels of wastewater per day.

Source: Colorado Oil and Gas Conservation Commission

Steve Lynn can be reached at 970-232-3147, 303-630-1968 or slynn@bizwestmedia.com. Follow him on Twitter at @SteveLynnBW.