An important tool in mapping the geology deep in the sub-surface is seismic reflection. This non-invasive technique enables us to obtain an image of the sub-surface structure and stratigraphy to determine the potential for trapping of hydrocarbons in an area.

revised Seismic picture march 2015

Seismic reflection surveys use an energy source at the surface (a small explosive charge in a shallow borehole or a vibrator truck) to generate a low-level seismic signal which penetrates deep into the earth. These seismic waves are reflected from different rock layers and a series of sensitive recorders called geophones record these reflections at the surface.

Egdon Vibrator Truck

Seismic surveys can be recorded along a single profile for example along a road (2D seismic) or cover a larger surface area to generate a volume of information (3D seismic).

The information in seismic surveys is recorded by reference to the time a sound wave takes to be reflected back to the surface and must be converted into depth using well and rock velocity information.