Survey vehicles in the Fylde

Geophysical
Survey

The Geographical Survey of Fylde was completed by 22nd June 2012.

A Geophysical Survey is a study of the subsurface geology – that is, the various layers of rock beneath the surface.

Using advanced imaging technology, the Survey mapped the layers of rock in the region improving knowledge of subsurface geology.

The process can be likened to a submarine’s use of sonar to generate an image of what it cannot otherwise see. In this case, we built an image of the rock beneath the surface.

How did it work?

The first stage of the Survey involved laying a temporary network of ‘geophones’ (similar to sensitive microphones) across the Survey area at ground-level to record energy signals. Wooden and metal pegs (poles) were also put into the ground.

To map (or image) the subsurface geology, we needed to generate energy signals. This was achieved using two separate processes.

The first process involved lowering small charges into specially prepared holes to a depth of between 6 to 8 metres. The holes were back filled and sealed. The detonation of the small charges generated the energy signals. The charges used were industry standard, used safely around the world, and were also small, using just 250 to 500 grams of Pentolite.

The other process involved using four tractor-like vehicles mounted with ‘vibrating plates’. The vehicles travelled both on and off-road, regularly lowering their vibrating plates to the ground in order to send energy signals down in to the rock layers.

Throughout the Survey, a number of service vehicles, such as Land Rovers, worked across the Fylde area maintaining equipment and measuring the activities to ensure they were safe.

We received authorisation from Lancashire County Council to undertake the Survey and worked closely with the Highways Agency and the police to plan the Survey route. In addition we received permission from individual landowners whose land we accessed.

Mapping the rock

In order to map the rock, energy signals travelled down into the rock formations deep below. The returning energy signals varied in strength and speed; and were recorded by the network of geophones in the area.

Energy signals are generated and recorded

 

Sophisticated computer technology processed this information, which will be used to create an 3-D image of the rock formation in that area. This information will provide us with what is effectively a geological map of what lies beneath our feet.

3d Data Image

Why have we done the Survey?

We carried out the survey to get a better understanding of the area’s subsurface geology.

Although there was some understanding from a similar survey carried out around 30 years ago, and from exploration drilling going back decades, the improved technology we used for this survey will allow us identify the depths of rocks, particularly the shale, in far greater detail.

This Geophysical Survey work, used alongside information from Cuadrilla’s wells, will mean that future work can be better targeted, with fewer well pads draining more gas.

The benefits

The Survey should help Cuadrilla target future work even more accurately, meaning less infrastructure and visual impact at the surface. We see this as an important benefit for the region.

In addition, all the data we accumulate will be sent to the British Geological Survey, enhancing the scientific and academic knowledge of the local geology.

The Survey also made a significant economic contribution to the area. It employed over 50 people from the area, who will have gained skills which could enable them to work on other similar projects around the world. Over the course of the Survey, the work made a direct contribution to the local economy of over £1.5 million.

Blackpool residents Wayne, Adele and John finishing the work on the survey, June 2012

When?

The Survey began at the end of March 2012 and took just over three months to complete – finishing on 22nd June 2012.

While the whole process took place over a number of months, work was constantly moving meaning operations were focussed on a single area for a much shorter period of time.

Who?

Cuadrilla commissioned CGGVeritas to carry out this Survey. CGGVeritas is the world’s leading geophysical company delivering a wide range of technologies, services and equipment.

Safety

Safety was an absolute priority throughout the Survey.

We worked to strict Health and Safety standards to make sure operations were safe for the public and our staff.

To establish the minimum safe distances from property and utility infrastructure, an independent local company, Spectrum Acoustic Consultants, who specialise in noise and ground vibration monitoring, tested the use of charges. The established safe working distance was set at 50 metres. Wherever possible, we increased this distance. Indeed, we put in place buffer zones around built up areas of 250 meters to reduce the impact of the work at key stages.

Moreover, throughout the work, we had teams closely monitoring the levels of vibration and noise to ensure they were within safe, permissible levels.

Importantly, CGGVeritas has been at the forefront of development of safety systems for the geophysical exploration industry and has several international experts in this field at its disposal.

Permission

In order to carry out the Survey we received authorisation from Lancashire County Council. We also worked closely with the Highways Authority and the police to agree routes.

Additionally, we have received permission from the individual landowners whose land we wish to access.

Keeping residents up to date

As part of our commitment to work closely with the communities we work within, we undertook a large scale and wide ranging communications effort to make sure residents living within the Survey Area knew what was going on.

This involved:

  • Over 30,000 leaflets sent to residents inside and outside the Survey Area, over a month before the Survey began
  • Over 15,000 leaflets sent to residents inside the Survey Area as work began, timed to coincide with the progress of the work in each area
  • Hand delivered letters providing at least 24 hours notification of work in a specific area and information about what to expect
  • Newspaper advert notices
  • Radio adverts on Radio Wave
  • Freephone Information Line telephone line operated on week days to provide specific information on the work

Geophones laid out

Drilling bore for charges