Production of hydrogen sulphide containing gas from underground formations

A process for the production of at least a gaseous product containing a substantial amount of hydrogen sulphide via a bore-hole from an underground formation containing besides the hydrogen sulphide at least elemental sulphur, comprising

• (a) injection of a liquid substantially consisting of hydrocarbons into the bore-hole or into the underground formation near to the end of the bore-hole;
• (b) producing a gaseous and a liquid fraction from the underground formation;
• (c) separating the gaseous fraction from the liquid fraction;
• (d) if necessary, separating an aqueous fraction of the produced liquid fraction from the hydrocarbons-containing fraction;
• (e) heating the hydrocarbons-containing fraction in order to remove elemental sulphur by conversion to hydrogen sulphide in the presence of a catalyst comprising sulphides of one or more metals from Group VIB and/or Group VIII of the Periodic Table of Elements deposited on a support of alumina, silica or silica alumina;
• and
• (f) reinjection of at least a part of the thus treated hydrocarbons-containing fraction into the bore-hole or into the underground formation near to the end of the bore-hole as described hereinbefore.