Frackingorhydraulic fracturing: what is it, how it works and what is its relevance to earthquakes. Fracking in Italy and earthquake in Emilia.
Not all substrates are the same and sometimes the deposits ofoil or gasthey are placed in "shale rocks", ie soils that flake easily and do not allowhydrocarbonsto be extracted efficiently.
Theretranslationof the termfrackingis "fracturing ", in geotechnics, the term is translated as "hydraulic fracturing"To indicate the practice of exploitation of the pressure of a fluid to create and then propagate onefracturein a rocky subsoil layer.
In practical terms, adrillingin a rock formation containinghydrocarbons. Yes drill a large hole near a gas or oil field. This increases the permeabilityin order to improve the extraction ofPetroleumor ofgascontained in thedeposit and increase recovery efficiency.
If the field exists, why do we practice thefracking?
To improve the extraction yield.
Thefrackingit is practiced especially when thehydrocarbonsthey must be extracted from low permeability rocks such as compact soils, cemented sandstones or clays. When thehydrocarbonsthey are "trapped" in non-permeable rocks, the traditional extraction process becomesinconvenientfrom an economic point of view as thePetroleumobtained would have a lower commercial value than the investments necessary for its own extraction.
For example, in the case ofbituminous rocks, it would be really difficultextracting natural gas. Bituminous rocks are extremely impermeable and thefracturesinduced would increase thepermeability of the rock around the extraction well. In this way, the extraction yield would increase.
Therefractureis called "hydraulics”Because it is created bypumping a fracturing fluid into the well(high pressure). The fluid can be water, gel or foam but more frequently a compressed gas such as nitrogen, carbon dioxide or gaseous mixtures is used.
Thefrackingthis is not a "recent" practicecontroversial techniqueit was used - albeit in a less widespread way - already at the beginning of the twentieth century.
How does it work?
The ground is drilled up to the deposit (atrockswhich contain thenatural gas or oil to be extracted) and, subsequently, a high pressure jet of a fluid (gas or liquid) mixed with solid components (quartz sand, ceramic microspheres ...) is injected. Solid components have the task ofkeep the fracture openeven when the pressure starts to drop. Thanks to fracturecreated, the emergence of the gas or oil to be extracted is obtained.
Is it harmful to the environment?
The massive use ofhydraulic fracturingaroused the interest of environmentalists. First of all, thefrackingsees a very high water requirement (a huge amount of water is used that must be transported to the exploration sites), another non-negligible factor, many chemicals are used which arepotentially harmfulfor human health and thatthey can contaminate groundwater present around the extraction site.
On the one hand, thefracking wastesa large amount of water and on the other, it riskspolluting groundwaterwith chemicals of various kinds.
Therehydraulic fracturingcould assist theseismic events. The cases that have been discussed are many. We remember the2012 earthquake in Emiliaand, in the previous year, the Oklahoma earthquake of November 6, 2011 when ashockwith a magnitude of 5.7, it hit the US state precisely following the insufflation ofhigh pressure fluids in the subsoil.
Shale rock deposits are also found in Italy but in our country the Environment Committee of the Chamber of Deputies approved a resolution that prohibits any activity related to fracking in Italy. The conclusion was reached by exploiting a "precautionary principle" that could see oneconnection betweenfracking and earthquakes.
If you are wondering if there is a correlation betweenfracking and the earthquake in Emiliaknow that in Italy thehydraulic fracturingit is a technique that has never been practiced. In the areas in Emilia there are some hydrocarbon extraction sites but they do not provide for the practice of hydraulic fracturing.
In the areas affected by the earthquake, in Emilia, at the time of the earthquake, the activity of the Casaglia geothermal plant and the hydrocarbon extraction field of Cavone, near Mirandola, was recorded. If the frackingit is to be excluded as the cause of the earthquake in Emilia, it is not possible to exclude (nor, however, accuse) that the other extraction plants could have had a role in triggering those earthquakes stimulating a fault already close to the breaking point.
Thefracking, in general, it can be dangerous when carried out near earthquake-prone areas, in the presence of faults. The correlation between earthquake and fracking in Oklahoma has been hypothesized on a more solid basis. In theory, any drilling activity (including thefracking) could assist a seismic event when a fault is in delicate conditions.
Even if the media attention is mainly focused on the correlation "fracking earthquake", It must be emphasized that if there are no strong certainties on this front, the risks of contamination of groundwater, water pollution, water waste, damage to aquatic fauna and soil pollution caused byhydraulic fracturing.