VERTICAL drilling has an uncertain outcome because of the variability of the porosity and therefore the oil / gas content of the shale even within the same deposit.
The hydrocarbon may be methane or have viscosity ranging up to tar. Horizontal drilling within the shale is used to increase access to the hydrocarbons. Fracking uses large quantities of water and a report by Marianne Stuart for the British Geological Survey has the title ‘Water Supply May Struggle To Cope With Demands Of Fracking’. A significant fraction of the water used is returned and must be tinkered away to remove the chemicals it contains for fracking.
Everything hinges on the scales of drilling used. If hundreds of exploratory wells are required it will put farm land in competition.
Clay particles are very small and remain suspended in a flowing river but settle when they reach the sea. In geological time they are compacted to form low porosity and permeability shales. Trapped organic matter forms a mixture of methane and liquid hydrocarbons whose escape can pollute land, water and air.
Pollution of air can lead to smogs and methane has a higher global warming effect than the CO2 we are trying to avoid.
GC Bye, Hurstbourne Priors
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