According to the results of a study done in China by Li et. al (2016), there is no method for measuring oil potential in shale reservoirs that includes both residual oil contents in the rocks as well as hydrocarbon expulsion and migration conditions. Li and his colleagues developed soon an index for determining oil potential. If the index is greater than zero, then some of the oil has migrated to external reservoirs which means that it has poor shale oil potential. Li et. al. argue that because current methods include absorbed, as well as free hydrocarbons, they are overvaluing the shale oil and not looking at oil that can readily be used. The method developed in this paper has multiple parameters and is a more comprehensive measurement since it takes into account oil saturation, free oil content, and shale oil expulsion. Continue reading →
An article written by the Louisiana Oil and Gas Association (LOGA) clearly explains the process of horizontal fracking in sedimentary shale rock located over 10,000 feet below the Earth’s surface. The article addresses all concerns that local land owners and communities could have. This article should be referred to those who have concerns regarding horizontal fracturing. I found the information to be very helpful when providing it to my own family. My father’s family owns close to 250 acres of land in Desoto Parish, Louisiana and with my grandfather recently passing my father and family join many other landowners and residents in having concerns of being exploited by major gas companies who are rapidly increasing production in the northwest region of Louisiana. Continue reading →
There has been a rapid increase in shale gas development in the united States due to the increase in use of hydraulic fracturing to access these shale beds. The rise of hydraulic fracturing has lead to intense public debates about the potential environmental and human health effects from hydraulic fracturing. Vengosh at el. (2014) identifies four potential areas of risks for water resources from hydraulic fracturing: contamination of shallow aquifers due to stray gas contamination, contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater, accumulation of toxic and radioactive elements in soil near disposal or spill sides, and the over extraction of water resources that could induce water shortages. To be able to fully understand the water contamination risks associated with hydraulic fracturing there needs to be an in depth investigation of the hydrology, hydrogeology, water chemistry, and isotopic tracers for identifying what the cause of the water contamination is. Continue reading →
Our newest book just Released! “Energy, Biology, Climate Change” and available at Amazon.com for $19.95.
The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.
This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading →
If by some miracle we as humanity collectively decide to reduce our greenhouse gas emissions enough to keep the planet from heating up by more than 2 ºC, there are going to be lots of fossil fuels left in the ground. Where will they be? For sure, there will be a good deal left: a third of remaining oil reserves, half of natural gas reserves, and over 80% of known coal reserves will still be unused by 2050. These reserves are defined as the sources that could be economically recovered today and that can be assigned a probability of production. For starters, McGlade and Ekins (2015) think that all fossil fuels in the Arctic, and all oil that could obtained by unconventional methods (such as hydraulic fracturing) ought to be left in place. They then look at all known reserves and partition them by cost of production, reasoning that the least expensive will be mined first. And they point out that, given the amount of reserves, the chances of us not using them is stark. Still, they are able to model the probable trajectory of temperatures using a mix of the available fuel sources. As the bottom line, it is abundantly clear that if we were once in fear of running out of fossil fuels, a more pressing current concern is that we might not. Continue reading →
The long term environmental concerns having to do with shale gas development are primarily greenhouse gas (GHG) emissions and freshwater consumption, as other forms of environmental degradation can be remediated over time. Ian Laurenzi and Jersey Gilbert (2013) of the ExxonMobile Research and Engineering Company performed a life cycle assessment (LCA) of both GHG emissions and freshwater consumption of Marcellus shale gas. The life cycle begins with well drilling and ends with burning the fuel for power generation. Using their elaborated system boundaries, the researchers found that a Marcellus shale gas well releases 466 kg of carbon equivalent units per megawatt hour of power produced (kg CO2eq/MWh) and consumes 224 gallons of freshwater per megawatt hour of power produced (gal/MWh) over the course of its lifetime. The biggest contributor to both GHG emissions and freshwater consumption is power generation. The result of this study are highly dependent on the variables chosen to represent the shale gas well life cycle, especially the expected ultimate recovery of natural gas. Despite the potential for variability of results, the result of 466 CO2eq/MWh is consistent with other published life cycle assessments for conventional and shale gas, and almost all of the 14 other studies fall within the 10%–90% range of 450–567 CO2eq/MWh. Even considering factors that can increase total results, this study shows that average GHG emissions from shale gas are 53% lower and freshwater consumption is 50% lower than what is required for an average coal life cycle. Continue reading →
If one of the big advantages of using supercritical CO2 rather than water for fracturing shale is that it effectively disposes of the CO2 by absorption onto the shale (Middleton et al. 2013—see Jan 13 post), some experimental evidence would be useful. This is provided by Lafortune et al. (2014) who obtained a sample of shale from a Mesozoic marine basin in France, dried and crushed it, put it on an ultrasensitive balance, and flooded it with CO2 at various pressures and temperatures. The highest pressure was 9 MPa (90 bar, or 90 times atmospheric sea level pressure) and the highest temperature 328 K (131ºF), just at the combination of temperature and pressure at which CO2 becomes supercritical (see figure). This is only about a tenth of the pressure sometimes achieved in actual hydraulic fracking, and probably a somewhat lower temperature than normally used, but might be all that is necessary when using supercritical CO2. The higher the temperature the less CO2 adsorbed onto the shale so that the observation by Middleton et al. that temperatures of supercritical CO2 drop suddenly at the shale when the pressure is released augur well for increasing CO2 adsorption. There was a nearly linear increase in the amount of CO2 adsorption onto the shale with pressure, with no sign of leveling off at the pressures these experimenters used, so that too suggests an effective means of both sequestering CO2 and releasing methane, although the adsorption was not as high as it would have been on coal, someplace else it might be profitably sequestered. Continue reading →
The purpose of hydraulic fracturing is to use high pressure to open up pores in deep fuel-bearing shale deposits so that the oil or natural gas can escape through boreholes to the surface. To make this work, very high pressures (hence, much surface equipment) and a great deal of water are required. To keep the pores propped open when the pressure and water recede, something (usually sand) needs to be included. The inclusion of acid can increase pore efficiency, and because water is a good biological medium, antibacterial agents may be required to prevent fouling. Finally, most of the fracking fluid returns to the surface where it presents a treatment and disposal problem. But in theory, any liquid, or supercritical substance, would work, supercritical CO2, for example. According to a study underway at Los Alamos National Laboratory (Middleton et al. 2014) sCO2 has a number of potential advantages over water, and some potential disadvantages as well. Continue reading →
Shale gas development physically and chemically alters the surrounding landscape, and native plants and animals can be particularly susceptible to these changes. In the Marcellus and Utica shale region—a largely forested area that encompasses the states of Pennsylvania, Ohio, and West Virginia—shale gas wells are being drilled with increasing density. A shale gas installation, including the well pad, compressor station, and storage areas, requires 3.56 ha on average. If an edge effect is considered, installations can affect approximately 15 ha of forest per site. Kiviat (2013) reviewed the potential ways that shale gas development can impact biodiversity. The most serious threats are physical alteration of terrestrial landscapes, chemical contamination of water and soil, and alteration of regional hydrology. Terrestrial alterations include construction of well installations, which cause deforestation and habitat loss, and construction of roads and pipelines, which create forest fragmentation. Chemical contaminants come from fracturing fluid and recovered wastewater. Hydrologic alterations are caused by water withdrawals and an increase in impermeable surfaces. Minor impacts on plant and animal health can come from noise, light, and air quality. Certain species are particularly at risk from shale gas development activities and some are able to thrive in the altered conditions. Continue reading →
How long will shale gas be available until it plays out? The Bureau of Economic Geology (BEG) at the University of Texas at Austin is making a concerted effort to find out for the four largest shale plays currently in development in the US. The first they reported on was the Barnett Shale in Texas. The topic of this post is their second study, conducted on the Fayetteville (Arkansas) Shale by John Browning and eleven colleagues at the BEG. The overall answer is a long time—but well short of a century—with production peaking soon and falling to between half and a third of the current levels by 2030 and continuing to decline thereafter; they ran their model through 2050 and estimate the technically recoverable gas resources if economics were not an issue (38 trillion cubic feet), and the amount likely to be recovered eventually given economic reality, about half that. Continue reading →