Gas fracking, or hydraulic fracturing as it is properly called, is a method of extracting natural gas from shale that has turned deposits that were previously impractical into vast sources of commercially viable energy. Immense deposits of shale gas are to be found in the many countries.
The process taps into layers of shale which were historically too impermeable to be economically extracted and opens pathways for gas extraction by pumping fluids into the rock under high pressure, fracturing the substrate and opening fissures leading into the well pipe through which the gas is drawn to the surface. Shale containing natural gas tends to lie in relatively narrow beds, so operators have turned to horizontal drilling, in which a vertical bore hole is drilled down to the strata and the drill then follows a horizontal path within the strata, increasing its contact with the gas bearing deposit.
There are many benefits claimed for gas fracking. One significant factor driving the industry is the quantity of energy available and the possibility that fracked gas may eventually reduce or even eliminate reliance on imported energy from other, frequently less reliable countries. The United States Department of Energy reckons that development of its shale gas reserves through fracking could turn the nation from a net importer to a net exporter of natural gas.
Natural gas is inherently cleaner burning than some other sources of energy such as coal or diesel. Approximately 45% of electricity in the United States is generated by burning coal, the world’s major source of greenhouse gas emissions and a significant contributor of air pollution. There is a great incentive to move towards using these natural gas reserves to improve the environmental aspects of energy production, now that fracking has made these large shale gas deposits become practical.
There are, however, serious reserves about the process, which has caused the industry to hit the brakes in some regions. Even though the fluids used are mostly water and sand, there is some chemical content, and traces of these chemicals have been found in well and surface water. The process requires the use of large quantities of water, which can strain local water supplies, and the waste water produced is contaminated with the products used and brought up from the depths, which can become a very significant factor, requiring major efforts to recover and clean. These are challenges that the industry claims it can overcome, for example by proper cementing and sealing of boreholes and responsible stewardship of the water supply and wastewater.
Finally, a bizarre and controversial result of gas fracking may be the creation of small earthquakes, as the fluid injected under pressure into deep rock lubricates faults and stress points and permits the release of strains in the strata. While these mini-earthquakes are generally of magnitude 3 or less on the Richter scale, they are large enough to be felt and the potential for at least some damage cannot be ruled out.
In the United States, development of fracked gas has benefited from the generous royalties earned by landowners whose properties overlie the basins where gas wells are drilled. The horizontal drilling method means that drilling and extraction equipment and installations can be located at a distance from the actual deposit, with the horizontal borehole extending up to 3 kilometres from the vertical bore. The financial incentive of royalties explains the public’s support to some extent. The situation is different in the UK, where much of the land exploited is crown land and there is little financial incentive for landowners to benefit. With the noise and machinery associated with drilling and little financial benefit seen by nearby residents, the UK has seen much greater resistance from the public.
Yet it appears that the future is going to include fracked gas. Despite the precautions needed, the advantages of large quantities of relatively clean energy, at least in comparison to other sources, means that the benefits are being seen as overcoming the disadvantages. The projects are employing many thousands of workers, both skilled and unskilled, and these workers are certainly not complaining.