Hydrocarbons are organic compounds, formed over millions of years occurring mainly in sedimentary basins. The most common types of hydrocarbons are petroleum, natural gas, coal and bitumen. “Hydrocarbons provide the major part of the energy for modern civilisation, providing power for heating, lighting telecommunications, industry and agriculture machines as well as all forms of transport and also provide the raw material for numerous products ranging from plastics to fertilisers”. (Global Non-Living Resources on the Extended Continental Shelf: Prospects at the Year 2000. ISA Technical Study: No.1) Oil and natural gas are hydrocarbon reservoirs that occur naturally within thick sedimentary sequences. These are largely confined to the continental shelves, continental slopes, continental rises, and small ocean basins.