Abstract: A process is described for the pretreatment of a pressurized natural gas which is saturated with water and contains hydrocarbons and hydrogen sulfide (H.sub.2 S) from a producing well. At least a portion of the natural gas (1) is brought into contact with at least a portion of recycled liquid condensate (2) in a cyclone (5). The vapor phase (6), containing H.sub.2 S and hydrocarbons, is cooled in zone (20), condensed and separated in separator (3). A gas (30) which is enriched in methane and depleted in H.sub.2 S is recovered while the condensate (8) is recycled to cyclone (5) after preheating if necessary. A water-containing liquid effluent (7) which is enriched in H.sub.2 S and depleted in hydrocarbons is recovered from the bottom of cyclone (5). This is reintroduced into the well (10).

Abstract: A process for the recovery of mercury and arsenic for which elementary mercury and/or mercury mercaptides are recovered prior to the recovery of arsenic and wherein the recovery temperature of the arsenic is higher than the recovery temperature of the mercury.

Abstract: A process for the elimination of mercury and possibly of arsenic from hydrocarbons wherein compounds containing mercury are transformed into elemental mercury, the charge is fractioned, and then the fractions rich in mercury are purified through contact with a mercury collecting mass.