The extraction of the natural gas from the Marcellus Shale involves two techniques that, when used together, can make extraction more efficient. The first technique is known as horizontal drilling. The natural gas is extracted from fractures in the shale, and therefore, a well should intersect the maximum number of fractures to maximize gas uptake. This is accomplished by drilling a well horizontally through the shale, perpendicular to fracture orientation.
(http://geology.com/articles/haynesville-shale/haynesville-shale-well.jpg)The other technique is known as hydraulic fracturing. This is the process of creating man made fractures in the rock, so that more natural gas can be extracted from the shale. This is done by injecting a mix of water and other chemicals under high enough pressures so that new fractures are created in the rock. A propping agent, such as sand, is added to prevent the fractures from closing when pumping pressure is released. Once gas is extracted, it can then be brought up through the well to the surface.
The controversy related to extraction of natural gas from the Marcellus Shale is related to the environmental risks associated with hydraulic fracturing. On March 18, 2010, the EPA announced a new $1.9 million study to examine the risks this practice may have on water quality and public health. Some are concerned about the chemicals that are added to the water that is pumped through the well under pressure. The risk of groundwater contamination as these wells pass through aquifers is a major concern. Another concern is the disposal of the fluid once the fracturing process is completed.
The EPA is right to investigate the safety of hydraulic fracturing, because any practice that could possibly impact drinking water should be examined very closely. With that said, I do believe that the natural gas reserves in the Marcellus Shale have enormous potential, and could be a major source of cleaner energy within the U.S. There is an estimated 168 trillion to 516 trillion cubic feet of natural gas in the Marcellus Shale formation. To put that in perspective, the U.S. currently uses about 1.1 trillion cubic feet annually. States located on the reserves, such as Pennsylvania, could run off of the gas for years into the future. The positive impact on the economies of the states located on the reserves could be significant. By working with the states, the EPA has an opportunity to ensure the safety of the extraction process, as well as encourage the utilization of energy reserves within the U.S. The EPA should examine possible new technologies and management practices that could reduce any risks associated with hydraulic fracturing. Once these technologies are considered, the EPA should oversee the extraction process. That way, it can ensure that these resources are utilized efficiently and safely.
I would disagree with the idea that it is worthwhile to extract natural gas from the Marcellus Shale. We too often are looking for easy ways to continue our dependence on fossil fuels at any cost. Hydrofracturing requires the use of a lot of water which then becomes highly contaminated. In this process there is usually a large amount of salt pumped up from underground that then must be dealt with. With water availability fast becoming a major environmental concern, it seems that we are slightly improving our energy issues while contributing to another growing problem. It seems we should protect our water now so we don't have more problems later.
ReplyDeleteI appreciate your perspective, and agree with much of what you bring up. However, I don't think that we can completely eliminate the use of techniques such as hydrofracturing for energy extraction. It is a technique that has been in use for many years, and while there are drawbacks, all energy production techniques at this point have some drawbacks. I look at natural gas extraction as a solid alternative to petroleum extraction, at least until better alternatives become more widespread.
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