Sealand Community Council

Proposed Vibroseis & Seismic Charge Geophysical Survey – Ferry Lane, Sealand. Explanatory Note.

Tesla Exploration International Limited acting for IGAS who hold petroleum Exploration and Development Licences for Chester and surrounding areas have given notification that they will be carrying out a geophysical survey under permitted development provisions during September and October to make a two dimensional image of the rock formations underlying the area.  This will assist IGAS in evaluating the rock structure which will help establish the probability of the presence of any naturally occurring gas, and which locations, if any, are best to carry out further exploration.

The southernmost part of the survey area includes Ferry Lane.  The survey will cover some 80 kilometres, mostly in Blacon, Ellesmere Port and Stanlow areas, with 1 kilometre being in Flintshire.  The survey will progress at a rate of 3 kilometres per day, so should only take about ½ day to complete the Ferry Lane section before they move on to the next location.

The survey uses tractors equipped with a vibrating plate which puts a low frequency vibration into the ground, and separate sensors manually placed along the length of the survey route will detect the vibration that is reflected back from the rock layers below.   The survey mainly takes place along public highways and hard surfaced private tracks, but on soft ground such as agricultural land, small charges buried in shallow boreholes are detonated to provide the vibration instead.  Any drilling is usually carried out using a land rover mounted shell and auger or rotary drill, and holes are sunk 6 metres deep and usually take a few minutes to drill.  Once detonated, the land is made good.  These are tried and tested methods of carrying out geophysical exploration surveys, and present minimal risk to people and the environment.

The operators have to comply with pre-set vibration limits and minimum stand off distances from utilities such as underground water/gas/power supplies, and residential buildings.  These surveys are designed to be carried out in built up residential areas as well as open countryside.  Any disruption associated with the survey is likely to be limited to traffic management, as the tractors will have to occupy narrow roadways and be stationary for the short period that they are operating the vibration unit.  The vibration lasts for less than 30 seconds and then the tractor moves 20 metres along to the next survey point.   A separate traffic management company is being employed to minimise any such short term traffic disruption.

Any follow up exploration drilling to take rock samples, or for gas testing, would have to the subject of a planning application made to the respective local planning authority.  This survey is an initial part of the exploration programme for onshore gas, and the future locations for any exploration and test wells are unknown at this time.  The main focus of current exploration activity falls within the Chester and Cheshire West administrative area