Fracking case study: The Marcellus Shale

The map below shows the vast number of shale deposits in the USA. Estimates of the potential natural gas reserves in these deposits could meet America’s energy needs for 90-116 years (Karbo et al 2010). For a country that has been one of the top importers of energy for the last decade there is huge appeal at the potential of being self-sufficient. Little wonder then the dramatic investment in hydraulic fracking technology: currently the only way to access the shale gas reserves. 

I am going to look at the case of the Marcellus Shale: by far the biggest reserve in the US and a hotly debated issue. It lurks beneath 10 states including New York and Pennsylvania then crosses the border into Canada.

Shale deposits of America (Image from Kerr, 2010, Science Volume 328)

The formation is about 400 million years old (Devonian era) and the black colour comes from the organic rich material. Setting up the horizontal drilling wells has proved to be expensive, costing $3-5 million each. Yet the income generated from the industry is huge: in Pennsylvania alone, extraction of natural gas has generated 29,000 jobs and bought huge revenue through taxes and investment. This is a little shot of the actual deposits from the Marcellus Shale containing the natural gas. 

Sample from the Marcellus Shale (image from Environment, Science and Technology Journal 2012)

Challenges of the Marcellus Shale

• Most of the gas is about 1.6km below the surface – the challenge of drilling increases with depth as rock hardness and pressure increases. Therefore the drill bit has to be replaced regularly and the therefore process is very slow. Up to 50% of the drilling cost is consumed by drilling the last 10% of the well.
• Protection of the natural flora and fauna at the surface – there are limits to the horizontal reach of each well to maximise extraction numerous wells across a wide area are installed. There is also a lot of new infrastructure and transport links that have been constructed
• Secure cementing of the well - this is essential to prevent leakage of gas or fracking fluids. Given the depth and temperature of the wells in the Marcellus Shale (35-51C) this is very challenging. It is believed that this led to the leakage of methane into local groundwater (Vidic et al 2013).
• Water consumption in extraction – up to 10 million gallons of water are required to complete the extraction per well. Transporting this much water has huge energy costs and also raises moral issues in periods of drought when water is needed for agriculture.  

Opportunities that are being pursued

• Advancements in drilling – using multilateral rather than horizontal drilling for more efficient access to the gas. Also using paraffinic fluids rather than diesel to reduce the amount of atmospheric pollutants by 85% (Karbo et al 2010)
• Using environmentally friendly fluids – using plant oils such as palm or soy instead of chemical based (Fracking Report 2008) 
• Improved drinking water – increasing monitoring and treatment of drinking water to ensure the local communities are not harmed and to increase public support for the industry

Overall, the business here has been hugely successful and given a huge boost to the local economy. It has produced 12% of all natural gas in America and this figure is predicted to increase for many years despite the controversy around the site.

Finally, it is just me or does the picture of the sample from the Marcellus Shale look a bit like a choc ice?