The present invention comprises a method for production of a CO2-rich gas stream and a H2-rich gas stream, the method comprising the following steps: a) natural gas and water are fed to a reforming reactor and are converted to synthesis gas under supply of a O2-containing gas: b) the gas stream from a) is shifted, whereby the content of CO is reduced and the amounts of CO2 and H2 are increased by reaction of H2O; c) the gas stream from b) is separated in a separation unit into a CO2-rich and a H2-rich gas stream, respectively. The invention also concerns the use of a CO2-rich gas stream for injection into marine formations, and the use of a H2-rich gas stream for hydrogenation, as a source of energy/fuel in fuel cells or for production of electricity.