Experimental determination on H₂S generation by thermochemical reduction reaction of sulfates

As a harmful acidic gas, H₂S is mainly produced by thermochemical sulfate reduction (TSR) reaction during the process of heavy oil thermal recovery with steam injection.The formation mechanism and effect of producing H₂S from four sulfate including CaSO₄, Na₂SO₄, MgSO₄ and Al₂(SO₄)₃ via TSR reaction were studied by experiments.The results showed that:(1) water was necessary for the TSR reactions and solid sulfate could not induce the TSR reactions.(2) The reaction rate of TSR was determined by the solubility of sulfate.The higher the solubility of sulfate was, the faster the reaction rate was.(3) The charge number of metal cation of water soluble sulfate determined the difficult degree of TSR reaction.The more the charge number was, the easier the reaction was.