Does fracking generate earthquakes? Averigualo Vargas

Prof. Carlos Alberto Vargas Jiménez, Universidad Nacional de Colombia

Miembro del Consejo Científico del Programa Internacional de Geociencias – UNESCO Ex-Miembro de la Comisión Independiente e Interdisciplinaria de Fracking.

 Universidad Nacional de Colombia

Some of my creative students of the seismology and geophysics courses at the National University of Colombia, brought to class the concern about whether it was feasible to harness the energy released by earthquakes generated in routine human activities of which we are not aware, for example, the Tremor generated by some manufacturing processes, the operation of hydroelectric plants, the exploitation of mines, the transport of cargo on roads, massive events in targeted sites such as concerts or football matches and, the landing of airplanes, among others.

We are not aware of the daily life of these seismic events, such as the one generated each time a medium-sized aircraft lands like a Boing 737-800 with a capacity of 154 passengers, which, when touching the ground, many times a day in Bogotá, Cali , Medellín, Barranquilla, and other intermediate cities in Colombia, release an energy equivalent to an earthquake of magnitude 0.7, and for a Boing 747-400 the magnitude is close to +1.2. Although we do not know how close we are to technological solutions to harness that energy, the bottom line is the naturalness of its occurrence without major significance. Most of us when we are at an airport, a few hundred meters from the runway, do not notice the impact, and perhaps it does not affect the adequately constructed homes adjacent to the airports, many of them located less than a kilometer away.

Thanks to the enormous controversy that has generated the multistage hydraulic stimulation in horizontal wells, a technique popularly known as fracking, we have more and more observations on induced seismicity, a phenomenon inherent in the oil industry. At the depth where the stimulation is performed (typically between 1.5-4km) the seismic magnitudes of the events are small and in a high negative percentage, that is to say very low. In an event of magnitude -2 (read negative), the energy is equivalent to dropping a phone book from a height of 6m. In the United Kingdom the upper limit allowed in fracking operations is +0.5, which is equivalent to the energy that a bi-articulated bus brings at a speed of 20km / h. If a bus of these collided (hopefully not pass), hardly anyone a kilometer away could feel it, much less a building, at this distance, would suffer damage.

In oil operations such as fracking or extraction of conventional resources as currently occurs in Colombia, oil and gas production is associated with large volumes of water, known as formation water, which is typically not potable due to the presence of salts and dissolved metals. There is engineering to purify it, but in some cases the required investments are high and the regulations must be adjusted for these purposes.

In any case, current regulations require that it be reinjected into the subsoil. This process in the medium and long term generates pressures in the rock that, given poorly managed scenarios, cause earthquakes in areas as far away as 40km. But the magnitude of these events depends on three factors: the first one is 1) how much the volume is injected ;, 2) the second the speed at which said operation is performed and the third and last; 3) the depth to which it is available.

Between December 2018 and January 2019, two earthquakes of significant magnitudes (5.7 and 5.3) were reported in the Sichuan Basin (China). The problem there is that the injection is done in a single well that collects water produced by more than 50 horizontal wells in production, and at distances between 6-16km. This generated overpressure conditions with the consequent reactivation of geological faults.

The Independent and Interdisciplinary Commission of Fracking, has evaluated this phenomenon in the case of being able to develop the pilot research tests that were recommended. The documented experience of the State of Oklahoma was guiding, since there is strict control of volumes, speed and injection sites of formation waters, which has allowed to avoid events of high magnitude. This was achieved thanks to a judicious exercise of scientific observation and subsequent regulatory adjustment. This is how regulation works as a result of informed policies. In conventional operations in Colombia there is an instrumental record of events that have reached a magnitude 4.6. There too, the subsequent adjustment in the administration of overpressures allowed the reduction of this type of seismic events.

A possibility to avoid any type of seismicity could be, for consistency, to prohibit certain industrial practices and in such case consider, among others, the unfeasibility of the tourism industry by preventing the landing of medium and large-sized airplanes that arrive in our cities Thousands of tourists every day.

Here it is necessary to remember that science, as a product of humanity’s most important collective effort, based on the permanent observation of phenomena, can approximate more accurate diagnoses and provide possible solutions to local realities without the need to exclude certain practices of society, or reject them when the evidence is really overwhelming, correctly attending to the spirit of the Principles of Caution and Prevention.

So another possibility would be that before taking the decision to allow or prohibit fracking in Colombia, a controlled experimental exercise, including physical and socio-environmental variables, is carried out. The State Council guarantees the construction of a State under ideals of objectivity. His recent clarification on the viability of the Integral Research Pilot Projects (PPII) stimulates the construction of objective knowledge that sets an example for the entire Nation and will allow informed decision making of importance to Colombia.

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