@Dr_Muhammaduu If your brother is interested in applying for an MSc scholarship, especially in Europe, I can guide him, as I graduated from the same department and university in 2020.
Some offshore rigs are actually semisubmersible (they float), especially in deep ocean locations. They use dynamic positioning systems (DP) to stay in place with the help of thrusters.
@hersoulspeaks__ Itโs almost impossible to build a fixed structure in the deep ocean. Thatโs why rigs like "Deepwater Horizon, you can search on Youtube" are semisubmersibles, they float, mainly used for oil exploration, then move to the next spot. Theyโre not used for permanent oil extraction.