Natural gas is providing a larger proportion of primary energy, and will soon surpass oil to become the most important fossil fuel. There are various genetic types of natural gas of which the type that pyrolysed or cracked from humic kerogen accounts for 70% of presently discovered global natural gas reserves. The parent material of humic kerogen is higher multi-cellular plants. Investigations of offshore basins in China, Russia, Indonesia, Bangladesh, Australia, Egypt and Namibia show that river-delta systems contain the major sources of coal-type gas. Sand and mud carried by rivers form deltas at river mouths and fertile soil of these deltas encourages the long-term growth of higher plants. Autochthonous higher plants and allochthonous terrigenous phytoclasts contribute to the formation of coal, carbargilite and dark mudstone, which are potential parent materials of natural gas and the basis of coal-type gas generation. There are various genetic types of natural gas of which the type that pyrolysed or cracked from humic kerogen accounts for 70% of presently discovered Global natural gas reserves. The parent material of humic kerogen is higher multi-cellular plants. Investigations of offshore basins in China, Russia, Indonesia, Bangladesh, Australia, Egypt and Namibia show that river-delta systems contain the major sources of coal-type sand and mud carried by rivers form deltas at river mouths and fertile soil of these deltas encourages the long-term growth of higher plants. Autochthonous higher plants and allochthonous terrigenous phytoclasts contribute to the formation of coal, carbargilite and dark mudstone, which are potential parent materials of natural gas and the basis of coal-type gas generation.