Injection well case highlights energy vs. water challenge in Wyoming
— March 13, 2013
Barring an objection from federal officials, EnCana Oil & Gas USA will be allowed to inject tainted “produced” water from its network of natural gas wells in the Moneta field into the Madison freshwater aquifer in central Wyoming.
Company representatives successfully argued that this particular portion of the Madison formation is much too deep (15,000 feet) and too remote to be considered an economically viable source of drinking water now and far into the future.
But this won’t be the last word on the matter.
In recent years the landowner advocacy group Powder River Basin Resource Council (PRBRC) has advocated for more conservation of Wyoming’s groundwater — in particular taking aim at consumption and water quality degradation sometimes associated with energy development.
“We are increasingly concerned about future sources of drinking water in Wyoming and in the Wind River and Big Horn Basin,” PRBRC chairman John Fenton wrote in a letter to the commission. “We believe that a decision to allow a potential drinking water aquifer to be exempted and removed from the potential for future use would be shortsighted and counter to the intent of the Commission regulations.”
Wyoming Gov. Matt Mead, who serves on the Wyoming Oil and Gas Conservation Commission (OGCC), said the demands, technology and economics for what constitutes a viable freshwater resource may drastically change over the next few decades. Mead said state officials have to consider “is it practical today vs. 20 or 30 years from now?”
The U.S. Environmental Protection Agency (EPA) still could object to EnCana’s injection plans, and even commission members had doubts about some of EnCana’s modeling and analysis.
The only two certified geologists on the five-member commission — Tom Drean and newly appointed Mark Doelger — both voted against EnCana’s injection well plan, due to suspected inaccuracies in EnCana’s hydrology modeling to estimate the reach of water quality impact.
“I am in no way faulting the work that EnCana has done. I am in no way faulting them or questioning their desire to properly dispose of fluids. … What I do have questions about in my mind is when they represent an impact area of 4.5 miles. That is not accurate,” said Drean, who also serves as Wyoming’s State Geologist.
A drop in the bucket
The approved wastewater injection rate of up to 25,000 barrels per day, and for a duration of up to 50 years, will only help meet EnCana’s “current and near-term” water management needs related to a few dozen wells in the Moneta Divide field 60 miles west of Casper.
In fact, the less controversial portion of the injection plan includes injecting another 25,000 barrels of produced water per day into the lesser-quality Nugget and Tensleep formations. EnCana also disposes produced water at the surface via evaporation ponds and other approved methods.
The controversial portion of EnCana’s wastewater injection into the Madison barely begins to address water management needs related to the industry’s proposal to drill an additional 4,250 wells in the Moneta Divide region.
“They’re going to have enormous quantities of polluted produced water that they’re going to need to dispose of. And if we’re going to exempt this aquifer, are we’re opening it up as a large disposal field?” said Jill Morrison, a PRBRC organizer.
Local and federal officials are just beginning to seek answers to these questions. The U.S. Bureau of Land Management in January initiated an Environmental Impact Statement (EIS) for the Moneta Divide Natural Gas and Oil Development Project, which may also include an amendment to the Casper BLM’s Resource Management Plan.
Rules and Rationale
While arguing their case before the commission for the single injection well and exemption to Madison’s freshwater classification, EnCana representatives avoided discussing specifics about future industrial water management needs in the Moneta region.
“This should not be tied to any future type development scenario. That would be speculative,” said John Jordan of EnCana.
Although the commissioners approved EnCana’s single injection well plan this week, concern about the massive scale of water management in the Moneta was voiced by commission chairman Ryan Lance; “We can’t look at this in isolation. … There are questions about how that next step in development will occur in this field.”
In a follow up interview, Lance told WyoFile that the freshwater exemption granted to EnCana applies only to a limited radius around the company’s injection well. Although the commission may not require a hearing for further freshwater exemption requests for the Madison formation in the Moneta field, operators wishing to drill injection wells outside EnCana’s approved radius of influence still must seek approval from OGCC staff.
“But they (OGCC staff) are going to be pretty cautious about how to approach that going forward,” said Lance, adding that the OGCC may change the terms of injection well permits based on water quality, injection pressures and other factors.
The approval this week to inject industrial wastewater into a freshwater aquifer is unique.
The Madison formation, which spans much of central and eastern Wyoming, and parts of Montana and South Dakota, is a primary source of municipal drinking water for many communities. It’s a primary source of freshwater for the city of Gillette.
But the Madison formation is as complex as it is large. In some areas, the Madison is tapped for the natural gas and other hydrocarbons it contains. The areas where the city of Gillette drills into the Madison for water are about 3,000 feet below the surface. The portion of the Madison that EnCana wants to use for wastewater injection is about 15,000 feet down, and yields smaller volumes and lesser quality water.
Because of these logistics, and because pollutants in one area of the formation cannot easily migrate to the Madison’s far reaches, EnCana was successful in gaining an exemption to freshwater aquifer standards based on the little-used criteria of economic and technological viability.
EnCana representatives also said their modeling — 50 years of injection at rate of 25,000 barrels per day followed by 50 years of no injection — would result in a minuscule increase in total dissolved solids (TDS) concentration in that limited area, still within the fresh groundwater standard.
Typically, production water associated with oil and gas is injected into aquifers of poor water quality — aquifers containing a TDS concentration of 5,000 milligrams per liter (mpl) or more. The Madison, where EnCana proposes to inject, had a TDS concentration close to 1,000 (mpl), and that triggered an objection by Wyoming DEQ in February.
Last month, both DEQ and EPA submitted a list of questions to EnCana. Upon review of EnCana’s answers (based on EnCana’s modeling), DEQ withdrew its objection, clearing the way for approval by Wyoming OGCC, which oversees Wyoming’s primacy over the federal Underground Injection Well Program.
Commissioner Bruce Williams noted that although EnCana’s current wastewater injection plan so far consists of one injection well for its current operations without being tied to more wells in the future, the operator is likely to disconnect older wells and add new ones as the development progresses over time.
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