Abstract: The invention relates to a method of pretreating a natural gas, water-saturated or not, essentially comprising hydrocarbons, a substantial amount of hydrogen sulfide and possibly carbon dioxide. The method according to the invention comprises an H2S-rich stream recycling stage.

Abstract: The method allows pretreatment of an acid gas that can comprise more than 10% H2S, for example a natural gas or a gas associated with the production of a crude petroleum effluent. The gas is dehydrated in unit DH, then cooled by heat exchangers E9 to E12 and by expansion carried out through valve V7. Cooling allows part of the H2S contained in the gas to be condensed. The condensates are separated from the gas in drum B1. The liquid recovered at the bottom of drum B1 is pumped and injected into well P to be sequestered in an underground reservoir or a geologic structure. The gas discharged at the top of drum B1 is depleted in H2S. This gas is sent through line 43 to a treating site in order to be subjected to additional treatments prior to being used.