Keele University
Applied & Environmental Geophysics
Explore this Section
Gas Extraction Should Continue
Professor Peter Styles was part of an expert panel that has produced a report for DECC following the earthquakes near to Blackpool last year.
The main points of the report are:
- Hydrofraccing did cause the felt earth tremors but they are still small and there have been larger events this year in the Potteries without causing undue alarm.
- From decades of observation of mining induced seismicity from similar rocks of similar ages we think that the maximum event which could be generated is about 3 which is usually not going to cause structural damage although it may be felt. However, we think it is possible to control the process so that events of even this magnitude don't occur.
- We propose a much more cautious hydrofracture process where less fluid is injected and the fluid is depressurised immediately after the fracture forms and is not held at pressure in the well for long periods as this can lead to fluid percolating along natural fractures and perhaps stimulating adjacent faults. This then allows the fracture to settle onto the sand/proppant which has been emplaced which is what creates the permeable pathways for gas to be extracted.
- We especially recommend detailed microseismic monitoring before, during and after the hydrofrac which will allow the fracture to be mapped and perhaps tuned and that this will allow a threshold level to be set at which they must stop working and assess carefully. This has been set at only 0.5 magnitude which is very low but we believe that we should be cautious in the next early stages although we may be able to relax this after experience is gained. The monitoring should assist in the fracking operations as well as wathcing for quakes.
- However, we do think that if we stopped hydrofraccing altogether now we would be none the wiser and as it shale gas is potentially a very important resource and would aid our energy security then we should try to see how it can be extracted safely and with all due attention to environmental protection.
Professor Peter Styles
Dr Ian Stimpson
< back
