May 2022 Offshore Site Investigation – Prof. Brian Georgious
Brian, a member of our geology group, introduced us to his involvement in the practical side of researching and using structures in the exploration for and exploitation of gas and oil reserves, for example, in the North Sea.
His definition of geo engineering was:
An offshore investigation for engineering purposes is a study to determine the conditions, hazards and parameters for the safe engineering design of offshore structures.
We were first introduced to the key features of marine geology and the 2 main processes involved in their creation – namely endogenic producing large scale features fuelled by heat sources and exogenic involving the process of erosion and sedimentation.
Then came an explanation of the variety of fixed and floating offshore structures that are operating, together with a whole range of specialist subsea items of kit. One intriguing example was a suction caisson where a reduction of air pressure internally literally sucks the whole structure into the sea bed.
First offshore rig 1947 in 6m water off coast of Louisiana
Today 7000 platforms in excess of 2000m water
We were introduced to an array of techniques used in site investigation offshore and to the range of geo hazards that might be encountered. Particularly impressive were 2 ships costing £140m + each used in this work and to hear about the dynamic positioning techniques employed to keep these ships in the exact same location. They are also designed to cope with up to a 3m swell whilst drilling. Other kit is designed to operate remotely on the seabed https://clearwellcaves.com/about-us/.
Brian told us about the hazard of landslides with particular reference to the Afen slide NW of the Shetlands which spreads 12 km in length from 830 km into the abyssal plain of the Norwegian Sea. It generated a tsunami affecting 600 km of Scotland’s coastline and swept inland up to 29 km.
Moving on we learned about the issues associated with different forms of methane. This is 24 times more potent than Co2. The scale of possible world wide release of the eg: caused by the melting of ice sheets or of perma frost is quite mind blowing and may well have contributed to major past global warming and the Permian mass extinction.
Concluding Brian reminded us of some of the blow outs that have occurred, especially the BP Deep horizon incident in the Gulf of Mexico.