In recent decades, new hydrocarbon extraction methods have been put into operation to cover the shortage of conventional crude oil. The most famous of them is hydraulic fracturing or fracking , a technique that accesses oil and gas trapped in very compact rocks and that is impossible to extract by conventional methods.
In his book Petrocalipsis , the physicist and researcher at the Institute of Marine Sciences of the CSIC (Barcelona) explains that, to reach these rocks, firstly horizontal perforations are used, which generally extend a kilometer or two in multiple directions. . Then comes hydraulic fracturing: “it consists of injecting water and sand under pressure at sudden impulses that are practically like explosions in order to fracture the compact rock and thus make it forcibly porous. With this, a much larger quantity of the oil stored in the rock is accessed, but – even so – it tends to stick to the stone and flows little, so that it is necessary to inject other substances that favor its drainage so that the oil be less sticky and can finally flow to the surface ”.
Although more research is still needed, some of the effects of fracking on the environment are known and well documented: the development of this productive activity requires the construction of large infrastructures that affect the landscape, biodiversity and natural resources of the region. zone . In addition, the explosions produce the release of various gases – some potentially toxic – and contribute to the greenhouse effect. For example, an article published in the Climatic Change Letters magazine estimated that in a few years the exploitation of unconventional oil and gas will leave a carbon footprint much higher than that of coal , because the elements associated with its exploration and use are more difficult to capture than carbon dioxide, the main greenhouse gas. One of these gases is methane and, according to a study published in 2019 in the journal Biogeosciences , the increase in the use of hydraulic fracturing seems to have contributed greatly to the increase of this gas in the atmosphere.
Water contamination
The use of various chemicals during the fracturing process poses a high risk of contamination of the surrounding aquifers. Now, the new study published in the journal Science indicates that surface water quality could also be affected as a result of these activities. According to the authors, small but detectable increases in salt concentration occur in surrounding surface waters, with the greatest impacts occurring during the early stages of production. However, the highest levels were below what the US Environmental Protection Agency considers harmful to health.
To reach their conclusions, the team of scientists combined a geocoded database of 46,479 fracking wells in 24 areas of the United States with 60,783 measurements of surface water quality from nearby watersheds, spanning an eleven-year period. . In this way they were able to examine whether drilling and hydraulic fracturing activities were associated with elevated salt concentrations, specifically bromide, chloride, barium and strontium . The results revealed a very small but constant increase in barium, chloride and strontium, but not in bromide, in those watersheds where new fracking wells had been installed.
Measurements needed closer to wells
The authors acknowledge a limitation in their study, and that is that most of the monitoring stations are far or even upstream from the wells, a factor that can cause the effect of extractive activity on water quality to be underestimated. “Administrations should place monitoring stations in places where impacts on surface water can be better tracked and the frequency of measurement increased just when new wells are drilled,” reflects Giovanna Michelon, a researcher at the University of Bristol and co-author of the work. “In addition, the other chemicals found in hydraulic fracturing fluids have to be tracked more systematically,” he explains, since these fluids contain chemicals that are potentially more dangerous than salts but are not usually included in the bases of public data, which makes a statistical analysis of large samples of these substances unfeasible .
Another opinion article published in the journal Science in the same issue and signed by two researchers in public health and economics from the universities of Rochester and Kentucky is also critical in light of the lack of research and the apparent laxity in regulation regarding this economic activity. . “Evidence of the impacts on water from unconventional oil and gas exploitation activities, together with studies of the impacts on drinking water, provide indirect evidence that water pollution related to these techniques influences health . Direct evidence is needed , ”they explain. “More generally, continued research in this field would provide information on the health benefits of surface water pollution control.” The authors indicate that, although the magnitude of the effects described in the new article are below the safety thresholds established for drinking water, the impact on health and the environment of the chemical emissions associated with the hydraulic fracture works, so the entire regulation should be rethought.
In Europe, the situation with regard to this activity is different. In our country, for example, the draft Law on Climate Change and Energy Transition has already set an expiration date: “as of the entry into force of this law, no new authorizations will be granted to carry out in the national territory, including the territorial sea, the exclusive economic zone and the continental shelf, any activity for the exploitation of hydrocarbons in which the use of high-volume hydraulic fracturing is foreseen ”, indicates the text, which also contemplates a scenario for the reconversion of the current holdings once the concession ends.
