A unique approach to monitoring groundwater supplies near Ohio fracking sites

This image shows a drilling rig in Carroll County, Ohio. -  Amy Townsend-Small
This image shows a drilling rig in Carroll County, Ohio. – Amy Townsend-Small

A University of Cincinnati research project is taking a groundbreaking approach to monitoring groundwater resources near fracking sites in Ohio. Claire Botner, a UC graduate student in geology, will outline the project at The Geological Society of America’s Annual Meeting & Exposition. The meeting takes place Oct. 19-22, in Vancouver.

Botner’s research is part of UC Groundwater Research of Ohio (GRO), a collaborative research project out of UC to examine the effects of fracking (hydraulic fracturing) on groundwater in the Utica Shale region of eastern Ohio. First launched in Carroll County in 2012, the GRO team of researchers is examining methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. The team travels to the region to take water samples four times a year.

Amy Townsend-Small, the lead researcher for GRO and a UC assistant professor of geology, says the UC study is unique in comparison with studies on water wells in other shale-rich areas of the U.S. where fracking is taking place – such as the Marcellus Shale region of Pennsylvania.

Townsend-Small says water samples finding natural gas-derived methane in wells near Pennsylvania fracking sites were taken only after fracking had occurred, so methane levels in those wells were not documented prior to or during fracking in Pennsylvania.

Hydraulic fracturing, or fracking, involves using millions of gallons of water mixed with sand and chemicals to break up organic-rich shale to release natural gas resources.

Proponents say the practice promises a future in lower energy prices, an increase in domestic jobs and less dependence on foreign oil from unstable overseas governments.

Opponents raise concerns about increasing methane gas levels (a powerful greenhouse gas) and other contamination involving the spillover of fracking wastewater in the groundwater of shale-rich regions.

“The only way people with private groundwater will know whether or not their water is affected by fracking is through regular monitoring,” says Townsend-Small.

The Ohio samples are being analyzed by UC researchers for concentrations of methane as well as other hydrocarbons and salt, which is pulled up in the fracking water mixture from the shales. The shales are ancient ocean sediments.

Botner’s study involves testing on 22 private wells in Carroll County between November 2012 and last May. The first fracking permits were issued in the region in 2011. So far, results indicate that any methane readings in groundwater wells came from organic matter. In less than a handful of cases, the natural methane levels were relatively high, above 10 milligrams per liter. However, most of the wells carried low levels of methane.

The UC sampling has now been expanded into Columbiana, Harrison, Stark and Belmont counties in Ohio. Researchers then review data on private drinking water wells with the homeowners. “We’re working on interacting with these communities and educating them about fracking as well as gathering scientific data, which is lacking on a very sensitive issue,” says Botner. “It can also be reassuring to receive data on their water supplies from an objective, university resource.”

The team also is seeking additional funding to begin monitoring groundwater wells near wastewater injection wells, where fracking brine is deposited after the wells are drilled.

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Funding for Botner’s research to be presented at the GSA meeting is supported by a grant from the Missouri-based Deer Creek Foundation.

Botner is among UC graduate students and faculty who are presenting more than two dozen research papers, PowerPoint presentations or poster exhibitions at the GSA meeting. The meeting draws geoscientists from around the world representing more than 40 different disciplines.

UC’s nationally ranked Department of Geology conducts field research around the world in areas spanning paleontology, Quaternary geology, geomorphology, sedimentology, stratigraphy, tectonics, environmental geology and biogeochemistry.

The Geological Society of America, founded in 1888, is a scientific society with more than 26,500 members from academia, government and industry in more than 100 countries. Through its meetings, publications and programs, GSA enhances the professional growth of its members and promotes the geosciences in the service of humankind.

Team develops a geothermometer for methane formation

John Eiler (left) and Daniel Stolper (right) with the Caltech-led team's prototype mass spectrometer -- the Thermo IRMS 253 Ultra. This instrument is the first equipped to measure abundances of rare isotopic versions of complex molecules, even where combinations of isotopic substitutions result in closely similar masses. This machine enabled the first precise measurements of molecules of methane that contain two heavy isotopes -- 13CH3D, which incorporates both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms. -  Caltech
John Eiler (left) and Daniel Stolper (right) with the Caltech-led team’s prototype mass spectrometer — the Thermo IRMS 253 Ultra. This instrument is the first equipped to measure abundances of rare isotopic versions of complex molecules, even where combinations of isotopic substitutions result in closely similar masses. This machine enabled the first precise measurements of molecules of methane that contain two heavy isotopes — 13CH3D, which incorporates both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms. – Caltech

Methane is a simple molecule consisting of just one carbon atom bound to four hydrogen atoms. But that simplicity belies the complex role the molecule plays on Earth-it is an important greenhouse gas, is chemically active in the atmosphere, is used in many ecosystems as a kind of metabolic currency, and is the main component of natural gas, which is an energy source.

Methane also poses a complex scientific challenge: it forms through a number of different biological and nonbiological processes under a wide range of conditions. For example, microbes that live in cows’ stomachs make it; it forms by thermal breakdown of buried organic matter; and it is released by hot hydrothermal vents on the sea floor. And, unlike many other, more structurally complex molecules, simply knowing its chemical formula does not necessarily reveal how it formed. Therefore, it can be difficult to know where a sample of methane actually came from.

But now a team of scientists led by Caltech geochemist John M. Eiler has developed a new technique that can, for the first time, determine the temperature at which a natural methane sample formed. Since methane produced biologically in nature forms below about 80°C, and methane created through the thermal breakdown of more complex organic matter forms at higher temperatures (reaching 160°C�°C, depending on the depth of formation), this determination can aid in figuring out how and where the gas formed.

A paper describing the new technique and its first applications as a geothermometer appears in a special section about natural gas in the current issue of the journal Science. Former Caltech graduate student Daniel A. Stolper (PhD ’14) is the lead author on the paper.

“Everyone who looks at methane sees problems, sees questions, and all of these will be answered through basic understanding of its formation, its storage, its chemical pathways,” says Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry at Caltech.

“The issue with many natural gas deposits is that where you find them-where you go into the ground and drill for the methane-is not where the gas was created. Many of the gases we’re dealing with have moved,” says Stolper. “In making these measurements of temperature, we are able to really, for the first time, say in an independent way, ‘We know the temperature, and thus the environment where this methane was formed.'”

Eiler’s group determines the sources and formation conditions of materials by looking at the distribution of heavy isotopes-species of atoms that have extra neutrons in their nuclei and therefore have different chemistry. For example, the most abundant form of carbon is carbon-12, which has six protons and six neutrons in its nucleus. However, about 1 percent of all carbon possesses an extra neutron, which makes carbon-13. Chemicals compete for these heavy isotopes because they slow molecular motions, making molecules more stable. But these isotopes are also very rare, so there is a chemical tug-of-war between molecules, which ends up concentrating the isotopes in the molecules that benefit most from their stabilizing effects. Similarly, the heavy isotopes like to bind, or “clump,” with each other, meaning that there will be an excess of molecules containing two or more of the isotopes compared to molecules containing just one. This clumping effect is strong at low temperatures and diminishes at higher temperatures. Therefore, determining how many of the molecules in a sample contain heavy isotopes clumped together can tell you something about the temperature at which the sample formed.

Eiler’s group has previously used such a “clumped isotope” technique to determine the body temperatures of dinosaurs, ground temperatures in ancient East Africa, and surface temperatures of early Mars. Those analyses looked at the clumping of carbon-13 and oxygen-18 in various minerals. In the new work, Eiler and his colleagues were able to examine the clumping of carbon-13 and deuterium (hydrogen-2).

The key enabling technology was a new mass spectrometer that the team designed in collaboration with Thermo Fisher, mixing and matching existing technologies to piece together a new platform. The prototype spectrometer, the Thermo IRMS 253 Ultra, is equipped to analyze samples in a way that measures the abundances of several rare versions, or isotopologues, of the methane molecule, including two “clumped isotope” species: 13CH3D, which has both a carbon-13 atom and a deuterium atom, and 12CH2D2, which includes two deuterium atoms.

Using the new spectrometer, the researchers first tested gases they made in the laboratory to make sure the method returned the correct formation temperatures.

They then moved on to analyze samples taken from environments where much is known about the conditions under which methane likely formed. For example, sometimes when methane forms in shale, an impermeable rock, it is trapped and stored, so that it cannot migrate from its point of origin. In such cases, detailed knowledge of the temperature history of the rock constrains the possible formation temperature of methane in that rock. Eiler and Stolper analyzed samples of methane from the Haynesville Shale, located in parts of Arkansas, Texas, and Louisiana, where the shale is not thought to have moved much after methane generation. And indeed, the clumped isotope technique returned a range of temperatures (169°C�°C) that correspond well with current reservoir temperatures (163°C�°C). The method was also spot-on for methane collected from gas that formed as a product of oil-eating bugs living on top of oil reserves in the Gulf of Mexico. It returned temperatures of 34°C and 48°C plus or minus 8°C for those samples, and the known temperatures of the sampling locations were 42°C and 48°C, respectively.

To validate further the new technique, the researchers next looked at methane from the Marcellus Shale, a formation beneath much of the Appalachian basin, where the gas-trapping rock is known to have formed at high temperature before being uplifted into a cooler environment. The scientists wanted to be sure that the methane did not reset to the colder temperature after formation. Using their clumped isotope technique, the researchers verified this, returning a high formation temperature.

“It must be that once the methane exists and is stable, it’s a fossil remnant of what its formation environment was like,” Eiler says. “It only remembers where it formed.”

An important application of the technique is suggested by the group’s measurements of methane from the Antrim Shale in Michigan, where groundwater contains both biologically and thermally produced methane. Clumped isotope temperatures returned for samples from the area clearly revealed the different origins of the gases, hitting about 40°C for a biologically produced sample and about 115°C for a sample involving a mix of biologically and thermally produced methane.

“There are many cases where it is unclear whether methane in a sample of groundwater is the product of subsurface biological communities or has leaked from petroleum-forming systems,” says Eiler. “Our results from the Antrim Shale indicate that this clumped isotope technique will be useful for distinguishing between these possible sources.”

One final example, from the Potiguar Basin in Brazil, demonstrates another way the new method will serve geologists. In this case the methane was dissolved in oil and had been free to migrate from its original location. The researchers initially thought there was a problem with their analysis because the temperature they returned was much higher than the known temperature of the oil. However, recent evidence from drill core rocks from the region shows that the deepest parts of the system actually got very hot millions of years ago. This has led to a new interpretation suggesting that the methane gas originated deep in the system at high temperatures and then percolated up and mixed into the oil.

“This shows that our new technique is not just a geothermometer for methane formation,” says Stolper. “It’s also something you can use to think about the geology of the system.”

Methane out, carbon dioxide in?

A University of Virginia engineering professor has proposed a novel approach for keeping waste carbon dioxide out of the atmosphere.

Andres Clarens, an assistant professor of civil and environmental engineering at U.Va.’s School of Engineering and Applied Science, and graduate student Zhiyuan Tao have published a paper in which they estimate the amount of carbon dioxide that could be stored in hydraulically fractured shale deposits after the methane gas has been extracted. Their peer-reviewed finding was published in Environmental Science and Technology, a publication of the American Chemical Society.

The team applied their model to the Marcellus Shale geological formation in Pennsylvania and found that the fractured rock has the potential to store roughly 50 percent of the U.S. carbon dioxide emissions produced from stationary sources between 2018 and 2030. According to his estimate, about 10 to 18 gigatonnes of carbon dioxide could be stored in the Marcellus formation alone. The U.S. has several other large shale formations that could provide additional storage.

The researchers’ model is based on historical and projected methane production, along with published data and models for estimating the carbon dioxide capacity of the formations. Clarens said that production records are available for how much methane gas producers have already extracted from the Marcellus Shale, as well as estimates of how much more they expect to extract. That provides a basis for determining how much space will be left in the formation when the methane is gone, he said. Clarens said gas would be adsorbed into the pores of the shale and held securely.

“This would be a way of eating our cake and having it too,” Clarens said. “We can drill the shale, pump out the gas and pump in the carbon dioxide.. I think this will get policymakers’ attention.”

He said his work deals with the chemical feasibility of the idea, and that additional studies must be performed to examine the economical, political and logistical implication.

“My field is carbon management – high-pressure carbon dioxide chemistry,” he said. “Right now, we are emitting huge levels of carbon dioxide, and we need new ideas on ways to store the waste.”

Clarens, who said he has no connection with the oil and gas industry, knows some in the environmental movement oppose hydraulic fracturing because of possible risks to ground and surface waters. However, he thinks this type of extraction is inevitable in many places and it is important to preemptively develop new strategies for handling the environmental implications, especially those related to carbon dioxide.

“There are a lot of people who say we need to get away from carbon-based fuels, and that may be possible in a few decades, but right now, fossil fuels power everything,” he said. “Finding ways to harvest these non-conventional fossil fuel sources without contributing to climate changes is a difficult but important challenge.”

Clarens said he believes he and Tao are the first researchers to propose this strategy. He hopes this paper will contribute to a discourse on how best to responsibly develop this booming resource.

Clarens, who received his doctorate from the University of Michigan, did his undergraduate work at U.Va., receiving a bachelor’s degree in chemical engineering in 1999.

New tool for measuring frozen gas in ocean floor sediments

<IMG SRC="/Images/409444153.jpg" WIDTH="350" HEIGHT="319" BORDER="0" ALT="The figure shows how methane migrates up through the seabed and escapes as plumes of gas bubbles. The image is taken from Westbrook et al. (2009) GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L15608, doi:10.1029/2009GL039191 – From Westbrook et al. (2009) GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L15608, doi:10.1029/2009GL039191″>
The figure shows how methane migrates up through the seabed and escapes as plumes of gas bubbles. The image is taken from Westbrook et al. (2009) GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L15608, doi:10.1029/2009GL039191 – From Westbrook et al. (2009) GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L15608, doi:10.1029/2009GL039191

A collaboration between the National Oceanography Centre (NOC) and the University of Southampton is to develop an instrument capable of simulating the high pressures and low temperatures needed to create hydrate in sediment samples.

Dr Angus Best of NOC and Professors Tim Leighton and Paul White from the University of Southampton’s Institute of Sound and Vibration Research (ISVR) have been awarded a grant of £0,8 million by the Natural Environment Research Council (NERC) to investigate methods for assessing the volume of methane gas and gas hydrate locked in seafloor sediments.

Dr Best, who is leading the project, explained: “Greenhouse gases, such as methane and carbon dioxide, are trapped in sediments beneath the seafloor on continental shelves and slopes around the world. Currently, there are only very broad estimates of the amount of seafloor methane and hydrate.”

The team plan a series of experiments on a range of sediment types, such as sand and mud. They intend to map out the acoustic and electrical properties of differing amounts of free methane gas and frozen solid methane hydrate.

The laboratory-based approach adopted by the team will involve the development of a major new Acoustic Pulse Tube instrument at NOC. Using acoustic techniques and theories developed by the ISVR team, they aim to provide improved geophysical remote sensing capabilities for better quantification of seafloor gas and hydrate deposits in the ocean floor.

“Not much is known about the state of gas morphology – bubbles. Muddy sediments show crack-like bubbles, while sandy sediments show spherical bubbles. Only dedicated lab experiments can hope to unravel the complex interactions. By creating our own ‘cores’ of sediment material in a controlled environment where we know the concentrations of methane or carbon dioxide, we can create models to help us with in situ measurements on the seafloor.”

There is significant interest in sub-seafloor carbon-dioxide storage sites. Methane hydrates are a potential energy resource that could be exploited in future. They may also contribute to geo-hazards such as seafloor landslides – it is thought that earthquakes and the release of gas hydrates caused the largest-ever landslide, the Storegga Slide, around 8,000 years ago.

Professor Leighton said: “The three of us have collaborated in recent years in an experiment that used acoustics to take preliminary measurements of gas in the muddy sediments revealed at low tide. Those measurements, and the acoustic theory we developed to interpret the data, provided exactly the foundation we needed to undertake this critically important study that will be relevant to the seabed in somewhat deeper waters.

“As a greenhouse gas, methane is 20 times more potent per molecule than carbon dioxide. There is the potential for climate change to alter sea temperatures and cause more methane gas to be released from seabed hydrates into bubbles which reach the atmosphere. It is therefore vital that we have the tools to quantify and map the amount of methane that is down there.”