ISN: The Promise and Perils of Fracking
The energy security potential of hydraulic fracturing continues to receive a significant amount of coverage, most notably in the United States and Europe. Yet the phenomenon also known as fracking is by no means a new technique for extracting hard to get natural resources: it has been in use in oil production since 1949. What is new, however, is the combination of fracking with horizontal drilling and – even more importantly – the increase in the price of oil over the past decade. This has turned prospects that were previously considered non-commercial into profitable opportunities.
The art of fracking
Understanding fracking requires a short introduction on the geology of hydrocarbons. Oil and gas is formed out of ancient organic material accumulated in sedimentary basins. If appropriate pressure and temperature conditions exist, organic material in the source rock decays and turns into either liquid or gaseous hydrocarbons. Once formed, hydrocarbon molecules will tend to escape from the source rock and migrate towards the surface, percolating through porous rock. If they meet a layer of rock that is not porous (a cap rock) they may accumulate in the porous rock beneath this layer. This is how a conventional oil or gas field is formed.
But it is also possible that the hydrocarbon molecules are trapped in a rock that is not porous, such as shale or other tight formations. In a conventional oil and gas field, drilling a well into the formation allows oil and gas to enter the well and escape towards the surface. Because the rock is porous, oil and gas will be free to travel through the rock into the well. But if the rock is not porous, or has limited porosity, oil and gas contained in the rock surrounding the well will not be free to travel to the well. Hence the well will have little or no productivity. Hydraulic fracturing is a technique whereby large volumes of water are injected into the well at high pressure to fracture the rock, and in this way increase its permeability, allowing oil and gas to flow into the well.
It is the pragmatic combination of horizontal drilling and fracking into tight (i.e. non porous) formations that has led to the major increase in the United States of production of shale gas first, and shale oil thereafter. The increase in production has been little short of spectacular, as shown in the following charts from the Energy Information Administration (EIA). MORE