When natural gas is discovered in deeply buried layers of shale, the most common method of extraction is fracking. This term is shorthand for horizontal hydraulic fracturing. The widespread deposits of gas bearing shale in the US is driving a vigorous debate over the need for energy and jobs versus the environmental damaged caused by fracking.
Natural Gas Fracking
The type of shale deposits that hold natural gas and even oil are found in many places throughout the US. These deposits occur in large swaths that cover the Northeast, the Midwest, the South and the Rocky Mountain regions. In Pennsylvania, the largest formation is called Marcellus Shale.
Often the shale is buried several miles deep. The layers are frequently quite thin, as little as 10 to 20 feet thick. The gas is held in pores in the rock or in small cracks naturally present. The natural cracks are usually vertical.
If a well bore can intersect a large number of cracks in the shale, then the gas in those cracks will flow into the well. If a large number of cracks are connected, then more gas will be available. To intersect a large number of vertical cracks, then, the well must be drilled horizontally. This is exactly what is now being done.
In addition, the process of hydrofracing can make many more cracks in the shale. This is accomplished by pumping large volumes of water, sand and lubricating chemicals into the horizontal well. The enormous pressure eventually causes the shale and surrounding rock to suddenly break, or fracture. When the pressure is released and some of the water pumped out, the sand remains in the new cracks. The sand holds the cracks open and the gas bound in the rock is released.
Supporters of fracking point to all the energy and jobs that result. Each well requires a drilling crew and employs numerous drilling services. In addition, the hydrofracking process often requires thousands of truckloads of water to be delivered to the well-head. As more and more gas wells are drilled, there is a growing demand for gas pipelines to get the gas from the wells to the gas distribution companies and then to the customers.
On the environmental side, opponents point out that more CO2 is generated per BTU of energy yielded than any other gas or oil production method. Numerous cases of drinking water contamination have also been reported, including gas, heavy metals and radioactive elements. The same cracks that allow easy extraction of natural gas also allow the toxic fracking chemicals to leach into aquifers.
No fracking is a commonly used slogan for the anti-fracking supporters. There are certainly places where the risk of fracking is too high. In other places, a well-run fracking operation can be quite safe.
When it comes to gas fracking jobs, they will be created by efforts on both sides of the debate. Gas and oil production will generate many jobs quickly. Cleanup of the damage and pollution will also create many long-term jobs.