February 15, 2012
Charting a new course: Geology professors, alumni address fracking issues through chemical research
The economic viability and environmental effects of hydraulic fracturing, or fracking, has raised questions and concerns, but research by Kansas State University geology professors and alumni may help solve these issues.
Fracking has attracted considerable attention in recent months for both its great potential in energy production and its possible negative effects on the environment.
Sambhudas Chaudhuri, professor of geology, and Matthew Totten, associate professor of geology, collaborated with university alumni in the energy industry to gather valuable information about a fracking event related to methane production from organic-rich black shales.
"We were drawn to the questions of gathering knowledge by chemical means about the fracture geometry and about abrupt decline in production rate from many instances of hydraulically-fractured reservoirs," Chaudhuri said. "Finding a reasonable chemical means may even answer some environmental issues."
Three K-State geology alumni assisted Chaudhuri and Totten in their research. John Miesse of Pablo Energy II LLC in Amarillo, Texas; Greg Riepl, an independent energy exploration entrepreneur in Oklahoma City; and Steve Massie of Hess Energy Corp. in Houston, supplied the professors with valuable information to formulate the geochemical project.
Fracking is a method used to extract oil and natural gas by injecting high-pressure fluids into rock formations. It increases hydrocarbon production from low porosity formations by using a high-pressure fracturing fluid, which is a mixture of water, fine sand particles and chemicals. The resulting fractures create interconnected fissures that allow methane gas and oil to escape into the well. Industry is very interested in hydrofracturing because it offers huge potential for energy production.
Two major obstacles relate to fracking. First, environmental groups are concerned that fracturing events could pollute groundwaters with metals and other chemical compounds. Second, periods of high productivity are sometimes followed by unpredictable large declines in productivity. This implies that reduction in pore throat size may be a result of precipitation of materials used for hydrofracturing. An abrupt decline is a huge economic loss to industry.
"We considered a different geochemical approach with a better prospect of achieving some of these same goals of economically viable gas and oil production from shale formations," Chaudhuri said. "This geochemical approach has proved effective as a tracer for many different other natural processes."
The approach analyzes the characteristics of a group of chemically similar elements in a fracking setting. It may provide insight into the production decline and explain the geometry of the fractures that develop from hydraulic fracturing.
"We struck an idea that rare-earth element analyses of flow-black fluids could lead us to reach some important goals of a fracking operation, which is intended for increased hydrocarbon production from very low porosity rocks rich in organic carbon," Chaudhuri said.
The researchers also characterized the rare-earth element distribution patterns of captured flow-black fluids and compared them with pressure-injected fluids used in making the fractures. Some amount of fractures produced went beyond the boundaries of the targeted production zone.
"The rare-earth element distribution pattern obtained for this study gives an insight into the potential chemical groups which can be involved in a precipitation reaction that may lead to a rapid production decline," Chaudhuri said.
With demand continually rising for natural gas, the results of the study could pay dividends for enhanced energy production.
"Shale gas that is entrapped in low porosity-low permeability black shales can play a critical role in meeting not only our own, but also global energy needs," Chaudhuri said. "Our suggested geochemical approach has the potential to help improve the production levels for the shale gas entrapped in black, organically rich shale formations."
The study was conducted in the famous Woodford Shale of Devonian age in Coal County, Oklahoma, perhaps the richest shale in the world. Results of the study were published in the November/December 2011 issue of Shale Shaker, the journal of the Oklahoma City Geological Society. The researchers also presented at the recent Midcontinent Section Conference of the American Association of the Petroleum Geologists.