Ionic liquids and use thereof for dissolving or preventing deposits, mainly formed by sulfur, which impair production of gas wells

A dissolving composition capable of dissolving deposits formed mainly by elemental sulfur, which are present in a drilling and/or extraction well for natural gas, or for hydrocarbons in which a natural gas fraction is present as associated gas, said composition comprising a dissolution solvent of elemental sulfur, optionally in admixture with at least one aprotic polar solvent, wherein said dissolution solvent is an ionic compound, or a mixture of ionic compounds, each ionic compound consisting of

• at least one anion, and
• at least one cation
• wherein said at least one anion comprises an aliphatic radical R and a carboxylate group (anion RCOO—) bonded to said aliphatic radical R,
• said aliphatic radical R having a number of carbon atoms ranging from 1 to 26,
• said aliphatic radical R also containing at least one thiol group —SH as a substituent of H atom or of a methyl group contained in said aliphatic radical R,
• said at least one thiol group being in position 2, 3 or 4 with respect to the carboxylate group.