查看文章

Thermochemical sulfate reduction (TSR) is the reaction between anhydrite and petroleum fluids at elevated temperatures to produce H₂S and calcite. In this study of the dolomite-hosted hydrocarbon gas reservoirs in the Permo-Triassic Khuff Formation, Abu Dhabi, a geochemically well constrained rock-gas system, we demonstrate for the first time a clear influence of rock texture and mineralogy on the rate and extent of TSR reactions and thus on H₂S concentration in the gas phase. The controls on the rate on H₂S accumulation were:

(1) TSR reaction kinetics. TSR became significant as temperature exceeded ∼ 140°C, a critical threshold temperature for chemical reaction between aqueous sulfate and aqueous methane.

(2) Anhydrite dissolution rate. Once initiated, the subsequent reaction rate was controlled by the rate of supply of aqueous sulfate to the reaction site. Sulfate limitation is indicated by …