Horse Hill Oil Site was discovered in 2015
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More than 100 earthquakes that shook southern England were likely caused by oil drilling, experts say. Previous studies had ruled out a connection, but new information about the geology of the area established a possible connection.
The earthquakes were all fairly small, measuring between 1.34 and 3.18 on the Richter scale, and occurred near Newdigate, Surrey, in 2018 and 2019. Residents reported that their house shook for several seconds.
At the time, there was speculation that the quake was related to oil drilling by British Oil and Gas, although the epicenter of the quake was within 5 to 10 kilometers of the company’s epicenter. horse hill Excavation site. However, previous research by the British Geological Survey (BGS) and others found that the earthquakes were rare and relatively close to the drilling site, but were naturally occurring and coincidental.
Now, Matthew Fox and Philip Meredith from University College London have taken a fresh look, using the latest understanding of the region’s rock composition, to suggest that the quakes were indeed caused by oil drilling.
The pair ran more than a million computer simulations based on the location and scale of the oil extraction, as well as the geological details of the surrounding area, making earthquake predictions more closely aligned with real-world phenomena than previously thought. I found that they match.
When oil is extracted from deep underground, it changes the pressure beneath the earth’s surface, which causes rock movement and can cause earthquakes. Fox said previously there was a discrepancy between the date of the earthquake and the date the oil was extracted, but this can now be explained by considering the geology of the drilling area.
The researchers found that in areas composed of porous Portland stone, pressure changes and rock movement can occur almost simultaneously, whereas in areas with dense Kimmeridge clay, pressure changes can be transmitted more easily. We have discovered that there may be delays due to the time required.
“To me, this makes it more likely that (oil drilling caused the earthquake),” Fox said. “The correlation between these two, between oil extraction and seismic activity, is very strong and suggests that there is a link.”
Fox said it’s still possible that the association is a coincidence, but it’s less likely than previous research had suggested. He hopes that further statistical analysis will allow him to accurately quantify the probability of chance, but the current data does not allow him to make any estimates.
British Oil and Gas controlled oil drilling at Horse Hill until October last year, when planning permission was withdrawn by Surrey County Council following a lawsuit brought by activists supported by Friends of the Earth. After that, the work was stopped.
A company spokesperson said: new scientist: “This was answered many years ago when BGS seismologists were convinced that this was a natural phenomenon related to the movement of deep unrelated faults many kilometers deep from the site. This is an incident that has been dealt with.”
However, Stuart Haszeldine of the University of Edinburgh said, Although he was not involved in this particular study, he has conducted his own research with colleagues and says a link between oil drilling and earthquakes is now very likely.
“We did a detailed study of these small earthquakes in Surrey and the possibility that the shaking was related to activity at the Horse Hill oil field,” Hasseldine said. “In my professional judgment, there was a clear link between the timing of the earthquake and the operational activities to produce oil and gas from the Horse Hill site.”
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