The surface of the ocean conceals many secrets – unexplored depths, grotesque life forms, and precious resources. To find these resources, a Norwegian company has developed a technology for scanning the bottom of the ocean in greater detail.
At a depth of 1000 meters, it is ice cold and dark. No natural light penetrates here. At first, only silhouettes are discernible in the glare of the underwater robot’s floodlights. Then strange, three-legged objects appear on the bottom of the ocean. They are receiver stations for electromagnetic waves transmitted into the seafloor, to visualize its geological strata and find resource deposits. When oil companies want to find out whether drilling at depth is worth the cost, they often rely on Controlled Source Electro Magnetic (CSEM) technology. This technology exploits the differences in the electrical resistance of different bottom layers to provide clues about the location and size of oil fields.
The CSEM technology uses a very strong power source to generate an electro-magnetic field, as well as several receivers to record the fields. These tripod receivers are placed on the sandy bottom and pick up electromagnetic signals that have been changed by the layers through which they passed.
5000 meters below the seafloor
In 2016, the Norwegian company Petro-Marker placed 25 new tripods in the North Sea. The special thing about this new measuring method is that, unlike other measuring methods, the company uses a vertical transmitter and receiver to find resources under the bottom. This enables a much more detailed resolution and measurement data up to 5000 meters under the sea floor, the company claims. The tripods are about 4 meters high and made from a combination of glass fiber and special foams. Due to the sensitive electronics, metal parts cannot be used. This far below the surface, the pressure is extreme and the salt water is aggressive. (…)