The French company S3 Smart Seismic Solutions will be responsible for data acquisition. S3 is a leader in advanced geological surveys and has extensive experience from all over Europe – including Denmark. Earlier this year, S3 conducted a similar survey on Lolland with great success, and they are bringing both their experience and their fleet of seismic vehicles and boats to the Greenstore area.
Advanced vibration trucks to perform precision work
Six identical French-made vibratory trucks will play the leading role in the large-scale survey. The model, called the Thomas Vibrator T65, looks a bit like a white garbage truck, weighs 30 tonnes and is 10 metres long. There are only 10 of them in the world and S3 owns them all.
The Thomas, as the S3 employees call it, is equipped with a 2.5 m2 vibration plate underneath it, which is lowered to the ground during short stops and generates low-frequency sound waves that are sent vertically underground for about 60 seconds.
The lorries will drive one at a time in carefully planned routes from east to west. After each measurement, the truck will move forward 40 metres and repeat the process. When the vibration trucks are in motion, they are travelling at approximately 20 km/h, but they have a top speed of over 80 km/h.
When the vibration trucks are in action, if you stand close to them, you will feel slight vibrations under your feet. The vibrations are directed downwards and not out to the sides, so buildings and houses are not damaged. And if the lorries drive past old or listed buildings, the distance will be increased and the pressure relieved for safety.
Detailed mapping with geophones
The vibrations are picked up and registered by the 40,000 wireless geophones that S3 deploys in the area. The geophones are small receiving units the size of a Coke can. They are equipped with advanced sensor technology that can measure and record vibrations and sound waves.
“The data collection allows us to create a three-dimensional model of the geological layers in the subsurface, giving us detailed knowledge about the thickness and nature of the layers. And it is precisely these details that are crucial for us to assess whether the subsurface is suitable for safe geological CO2 storage,” says Regitze Reeh, Head of Communications at Harbour Energy, which holds the Project Greenstore licence together with INEOS Energy and the Danish state’s underground company, Nordsøfonden.
