Estimates for Greenhouse Emissions from Shale Production Overstated -Study

- Estimates for Greenhouse Emissions from Shale Production Overstated -Study

Wednesday, August 24, 2011
IHS CERA

Estimates used by the United States Environmental Protection Agency (EPA) and others for greenhouse gas emissions from upstream shale gas production are likely significantly overstated, according to a new report by IHS Cambridge Energy Research Associates (IHS CERA). The estimates are based on assumptions that do not reflect current industry practice and should be reevaluated, it says.

"Methane emissions have become a very important and controversial issue given their potency as a greenhouse gas," said Mary Barcella, IHS CERA director of North American natural gas. "Unfortunately, such emissions are not being measured. Estimates are being used that are not supported by data, do not reflect current industry practice and would be unreliable to use as a base for decision-making."

The report cites as one example the EPA's 2010 revised estimates of methane emissions during well completion—the period after the well has been drilled but before it is placed into production. The current EPA methodology for estimating methane emitted during this phase was based on a small sample of wells and primarily measured methane that was captured rather than released into the atmosphere, the report says.

The EPA estimates were based on two workshop presentations describing methane captured during "green completions"—operations designed to capture as much methane as possible. The EPA assumed that (1) similar levels of methane were produced at every other well in the United States and (2) that those emissions went completely uncaptured. Such assumptions do not conform to current industry practices, the report says.

"The assumption that all methane recovered from these sample wells would otherwise have been flared or vented is questionable at best, given that common industry practice is to capture gas for sale as soon as it is technically feasible," said Surya Rajan, IHS CERA director. "Gas that cannot be sold is generally flared rather than vented for safety reasons. If the methane emissions at wells were as high as some methodologies assume, you would have extremely hazardous conditions at the well site that neither regulators nor industry would permit."

Another key mis-characterization found in the EPA estimates and other recent reports, such as a study led by Cornell University professor Robert W. Howarth, is the assumption that wells in flowback contain methane in quantities equal to their post-completion daily production, the report says. This assumption results in a significant overestimation of methane emissions. (The flowback phase is the phase of production when fluids injected into the well flow back out ahead of the tapped gas.)

The IHS CERA report notes that data on unconventional gas well GHG emissions is currently lacking due to the fact that they are not adequately measured. More reliable data is needed in order to produce estimates with any degree of certainty.

The report says that the most productive result of additional regulations proposed by the EPA in July could be better documentation of actual GHG emissions which would provide the accurate measurement that is needed. Some of the other proposed regulations, such as requiring green completions and flaring of any produced gas that is not suitable for sale, are already common practice in the industry, it says.

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Oil-Extraction Method Could Reduce Greenhouse Gas

- Oil-Extraction Method Could Reduce Greenhouse Gas

Monday, June 13, 2011
The Columbus Dispatch, Ohio
by Spencer Hunt

A gas tied to climate change could someday bring new life to old Ohio oil fields.

State officials are investigating whether carbon dioxide could be used to draw millions of barrels of crude oil from fields that were all but played out.

Energy companies have injected carbon dioxide into old oil fields in Texas and California for decades. The gas increases the pressure underground and mixes with the oil, freeing it from nooks and crannies.

"It lightens the oil. It fluffs it up," said Larry Wickstrom, chief of the Ohio Geological Survey. "It actually makes it so you can push (the oil) through."

Wickstrom oversaw Ohio's first test, during which 81 tons of carbon dioxide were pumped into a low-yield well about 10 miles southeast of Canton in Stark County.

After the injection in 2008, the well produced 58 percent more oil. The results were so promising that they inspired a state proposal for more-extensive testing by Columbus-based research giant Battelle and $11 million in federal funding.

Officials say the project could help reduce climate change and increase U.S. oil production.

"There is a substantial opportunity here," said Neeraj Gupta, Battelle's senior research leader for geological carbon storage.

The idea isn't embraced by all. Environmental advocates say that a substantial amount of carbon dioxide returns to the surface with the oil.

"I don't doubt the workability of enhanced oil recovery," said Nachy Kanfer, the Midwest coordinator of the Sierra Club's coal-to-clean-energy campaign. "I doubt carbon dioxide's ability to remain underground."

Carbon dioxide was first used in the oil fields of western Texas in 1972. Wickstrom said it hasn't been used in Ohio's oil fields because there is no readily available supply.

That might seem a little strange, considering the millions of tons of carbon dioxide that coal-fired power plants in Ohio emit each year. But capturing and transporting the gas is not cheap.

FirstEnergy's Sammis plant and American Electric Power's Cardinal plant, which are along the Ohio River, emitted a combined 23.1 million tons of carbon dioxide in 2010. They are within about 40 miles of the test site.

The process to draw a pure stream of carbon dioxide can consume one-third of a power plant's electricity. Power companies still are testing equipment that could do that.

Gary Spitznogle, AEP's director of new-technology development, said power plants probably would charge $80 to $100 per ton to cover their costs. He estimated that commercial carbon dioxide sells for $20 to $40 a ton.

Wickstrom and Gupta said the money made by wringing more oil out of the ground could help offset those costs.

The test site was at the 175,000-acre East Canton oil field in Carroll, Harrison, Stark and Tuscarawas counties. Officials say that more than 1 billion barrels might remain there. Pumping carbon dioxide into the wells could draw as much as 279 million barrels from the field.

A more-extensive test at the site, involving as much as 20,000 tons of carbon dioxide injected over months, would help to confirm those early estimates, officials say.

Wickstrom said the state and Battelle have applied for an $11 million U.S. Department of Energy grant to help conduct that test. They won't know until September whether they'll get the money.

In the meantime, Battelle is involved in several federally funded projects to see whether carbon dioxide can be safely injected and stored underground. It's also helping AEP test a system that captures and injects 1.5 percent of the carbon dioxide produced by its Mountaineer power plant in West Virginia.

As far as using carbon dioxide to free oil, a larger test also would show how much of the gas resurfaces with the oil.

Wickstrom said that, on average, 20 to 30 percent of the carbon dioxide that's injected comes back up.

Gupta said wells in Texas and California include equipment to capture the carbon dioxide that comes off the oil so that it can be recycled and reinjected.

"There is a huge economic potential for more oil supply and storage of CO2 if we can make this work," Gupta said.

Copyright (c) 2011, The Columbus Dispatch, Ohio

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