By Bob Shively, Enerdynamics President and Lead Instructor
Those who follow environmental issues and/or are involved in the energy industry have no doubt heard about the fracking debate. One headline announces that fracking is a huge advancement that has given us a huge new supply of domestic natural gas supply (see for instance this summary of a talk by U.S. Department of Energy Secretary Steven Chu). The next headline reads that fracking is one of the biggest current threats to the environment and human health (see Greenpeace’s take on the issue). This article examines what fracking is and the potential environmental issues at the heart of the fracking debate.
What Is Fracking?
Hydraulic fracturing, commonly called “fracking,” is a method of stimulating gas flow in underground formations. Under so-called conventional natural gas production, the underground formations that hold natural gas are permeable rock meaning that small holes and fissures in the rock allow gas to flow within the formation. The gas is normally trapped by a layer of non-permeable rock that forms a cap. To produce natural gas, a well is drilled into the rock holding the gas and the gas flows from the higher pressure underground to the lower pressure wellhead.
The need for fracking arises when the rock holding the gas does not have sufficient permeability to flow adequate volumes to make a well economic. Producers have learned that by increasing permeability of the rock, more gas can be recovered. This is the purpose of fracking, which is a technique that fractures the underground rock as a means of increasing the flow.
The process of fracturing begins with drilling a well. First the well is drilled vertically, but once the desired depth is reached, the well is then drilled horizontally. After pipe has been inserted in the well and the pipe has been cemented in, perforations are made in the pipe and cement in sections where gas flow is desired. This is done using a device called a perf gun. Next, a mixture of fluids including water and chemical additives are pumped into the well at high pressure. The fluids flow through the pipe and out the perforations and, given the high pressure, cause fractures in the rock. When the fluids are then pumped back out of the well, gas flows through the newly created fractures, into the pipe via the perforations, and then to the wellhead. (For a good video of the process see the American Petroleum Institute’s website.)
What Fracking Technology Has Done for Gas Reserves
The technique of fracking has resulted in a huge boost to U.S. gas reserves. It allows more gas to flow from some conventional wells, but more importantly, it allows use of gas in formations where the rock is not permeable enough to allow economic gas production. The key unconventional resource is shale gas, which in 2009 made up 14% of U.S. gas supply but is projected to increase to 45% by 2035 according the U.S. Energy Information Administration.
Production of these unconventional reserves is not possible without fracking. So using these techniques means we have access to a large domestic energy resource that is the cleanest of the fossil fuels and is useful for heating our homes, running our power plants, and fueling large industry such as chemical production. And gas power plants function well with renewable energy production since gas units have the flexibility to ramp up and down in response to variability of wind and solar supply.
This provides a good summary of what fracking is and what it can do for the natural gas industry. In next week’s post we’ll examine why natural gas fracking is in the hot seat with environmental groups as well as if and how the issues can be resolved.