FAQs: Surrey Tremors

1. Have there been earthquakes?

Between April 1st and July 18th 2018 a series of small earth tremors were detected on the Surrey Sussex border. According to BGS data from the interactive map these were:

Date Magnitude
1/4/18 2.7
1/4/18 1.9
1/4/18 1.8
28/4/18 1.5
27/6/18 2.6
27/6/18 2.4
29/6/18 2.4
5/7/18 3.0
10/7/18 1.9
18/7/18 1.9
18/7/18 2.5

2. How severe are they?

All of these tremors were magnitude 3 or below which means that most people would not notice them even if very close to the centre. In general, these sorts of tremors would not cause any surface effects.

3. Were they caused by Angus Energy’s operations at Brockham?

Absolutely Not.

4. How can you be sure?

Angus Energy has not performed any subsurface work or major operations for at least 18 months.

In fact, no oil company in Surrey has had any operations during this period of seismic activity.

All earthquakes before 200 years ago and most earthquakes now have a perfectly natural origin due to movements in the rocks beneath our feet. So for example just before and during these tremors much more significant tremors occurred in Grimsby (magnitude 3.8) on 9/6/18 and in South Wales on 17/2/18 (magnitude 4.6). These were clearly naturally occurring.

In fact, no oil company in Surrey has had any operations during this period of seismic activity.

5. But aren’t you drilling?

Nope. No drilling at all, it has been this way for over a year before the beginning of the seismic activity.

6. Are you fracking?

Never.

7. I read you are using water to fracture rocks. Or using ‘Water Injection’?

Absolutely not true.

This is merely scare tactics by uncompromising activists to gain attention to magically show we are fracking. It has no basis in reality or fact and as mentioned, we don’t frack.

Our normal operating process since 2007 is to replace water back into the Portland Sandstone reservoir. Water is separated from the oil / water mixture produced and put back where we found it. The water is a natural part of the reservoir.

The reservoir also has its own natural pressure. We won’t go into a long science lesson, we can assure anyone, we’ve had no effect on the natural reservoir pressure.

The reservoir pressure at ~600m depth is at approximately 1/3 of the pressure required to fracture any rock. The Company does nothing to increase or moderate it.

8. Are the earthquakes near your wells?

The centres of these tremors ranged from 6.9 to 10.4km to the south of the Brockham Field with the scatter of centres around 9.3km to the South.

9. Could you have caused these tremors from Brockham under any conditions?

No.

To be clear, there cannot be any link between production and water replacement in Brockham and these events. This is because the Brockham field is sealed to the south by a fault. If this fault did not seal there would be no oil there. So oil and water cannot move from the Brockham field anywhere to the south.

10. So why are we having earthquakes now?

Good question!

We would like to know because we are professional geologists, we love this stuff.

The one thing we do know, from the facts and science, is that the Brockham Oil Field and / or Angus Energy is not the cause of the recent seismic activity – despite the unsubstantiated claims and wilful disregard of science by environmental ‘journalists’ and professional activists. Potential sources closer to the field, that have nothing to do with Oil fields, are simply ignored as they do not fit their uncompromising agenda.

There have been a large number of earth tremors recorded around the weald since the first mention as long ago as 1299. These all had natural origins. The Weald Basin is folded dipping down to the North and South. The rocks in the Weald behave not unlike a bar of chocolate when you try to bend it, it breaks. So there are a large number of east/west breaks or faults. The Weald is also subject to tiny earth movements that cause stresses in these faults and cause them to move occasionally. Over the billions of years of the earth’s history these movements were all naturally occurring.