Petroleum verticals are divested as Reservoirs, Drilling, Subsea and Surface Production etc, whereas Oil & Gas horizontals deprived as Pipelines, Refineries, Tank Farms, Distribution Piping Networks, Pet-rochemical Plants etc. One simplest way is to explain that Petroleum activities are not seen by naked eye which happens in the Subsoil and Underwater, whereas Oil & Gas activities are pretty visible which happens above water and on the land. This book explains the Offshore Crude Separation for Oil & Gas Development Platforms and FPSO’s and covers the scientific theory of upstream, midstream and down-stream processes of Oil & Gas which are technically paraphrased as, extracting Crude Oil in the Ocean, transporting through Subsea Pipe-lines to Onshore Terminals and storing in Tank Farms, Refining and Retailing to Customers.