Hydraulic fracturing has its problems, and one of the most extreme of these is that it can cause earthquakes. A new study has once again found that fracking does indeed cause earthquakes, however what is surprising is that conventional extraction of oil and natural gas causes more.
The study, ‘Induced Seismicity Potential in Energy Technologies’, and compiled by the National Research Council (NRC), looked into all earthquakes that have been linked to the full range of underground energy technologies, from conventional oil and gas wells, and geothermal energy, to carbon sequestration.
The highest earthquake risks do not come from drilling the well, or using pressurised water and chemicals to fracture the rock, but rather when wastewater from the processes is pumped deep into the formation for permanent disposal. There is also a high chance of triggering earthquakes when water or gas is injected into ageing wells in order to force the remaining contents to the top.
Wastewater injection is held responsible for earthquakes that occurred in Youngstown, Ohio on Christmas Eve and on New Year’s Eve, measuring 2.7 and 4.0 respectively.
Earthquakes are mainly caused during processes which have an imbalance between the pressure of fluids injected and extracted. Murray Hitzman, professor of economic geology at the Colorado School of Mines, and chairman of the organisation that wrote the report, said that “the two techniques with the largest imbalance are carbon sequestration and wastewater injection.” They both increase the subsurface pressure across large areas, producing a greater chance of hitting a fault and triggering an earthquake.
In order to avoid earthquakes the NRC recommend that energy companies involved in underground operations should work with the US Department of Energy in order to establish a set of best practices aimed at minimising the chance of earthquakes.
By. James Burgess of Oilprice.com