A new study suggests new guidelines in order to mitigate the earthquake risk triggered by hydraulic fracturing.
Hydraulic fracturing is a drilling process that aims at connecting existing cracks in the rock mass and creating new fractures. It utilizes a high-pressure injection technique and its purpose is to increase the permeability of rock formations and, thus, allow oil or gas to be extracted.
In addition, hydraulic fracturing is a process that is potentially linked to the generation of earthquakes. Most of the times, the seismic shocks are subtle but sometimes bigger tremblors can be triggered. A new study, recently published by scientists at Stanford University, California, recommends a new procedure to pause or slow hydraulic fracking before an earthquake occurs.
Currently, the risk of fracking is evaluated based on the size of the generated earthquakes. However, researchers explain that seismic shocks of the same size may lead to different ramifications based on the location and the surrounding environment of the fracking site. For example, the impact of similar earthquakes in the center of a city and in a rural, uninhabited area would be completely different.
Moreover, local geological conditions such as stratigraphy, faults and epicentral depth also affect the impact of the generated earthquakes and should be accounted for in a risk assessment analysis. “Implicitly, I think regulators have had risk in the back of their mind. But risk-based frameworks have not been used previously – perhaps because it requires a bit of extra analysis,” Dr. Greg Beroza, co-author of the study and Professor of Geophysics at Stanford University, stated.
The team employed a new technique that considers these important parameters within an earthquake risk analysis framework. They utilize a system known as traffic-light protocol which is a risk management system that takes into consideration site characteristics and real-time measurements. The system works as a traffic-light. During green light, fracturing can continue normally as earthquake hazard is low but, when the light is yellow or red, certain adjustments or halts must be implemented.
The scientists developed complex mathematical models to include all the aforementioned factors in their analyses. They calculated the earthquake risk factor at a specific location and managed to link their results with the current system that is based on the size of earthquakes. Therefore, their traffic-light approach can utilize earthquake magnitude to quantify the potential earthquake risk but the models also incorporate local factors of the region where hydraulic fracking is conducted.
“If you tell me what exposure you have in a certain area – population density, site amplification, distance to towns or critical infrastructure – our analysis can spit out numbers for green-, yellow- and red-light thresholds that are fairly well informed by real-world risks,” Ryan Schultz, lead author of the study and a Ph.D. student in geophysics at Stanford University, stated.
To learn more about hydraulic fracturing, watch the video below.