Distribution and treatment of harmful gas from heavy oil production in the Liaohe Oilfield,Northeast China

The distribution and treatment of harmful gas (H₂S) in the Liaohe Oilfield, Northeast China, were investigated in this study. It was found that abundant toxic gas (H₂S) is generated in thermal recovery of heavy oil. The H₂S gas is mainly formed during thermochemical sulfate reduction (TSR) occurring in oil reservoirs or the thermal decomposition of sulfocompounds (TDS) in crude oil. H₂S generation is controlled by thermal recovery time, temperature and the injected chemical compounds. The quantity of SO₄²⁻ in the injected compounds is the most influencing factor for the rate of TSR reaction. Therefore, for prevention of H₂S formation, periodic and effective monitoring should be undertaken and adequate H₂S absorbent should also be provided during thermal recovery of heavy oil. The result suggests that great efforts should be made to reduce the SO₄²⁻ source in heavy oil recovery, so as to restrain H₂S generation in reservoirs. In situ burning or desulfurizer adsorption are suggested to reduce H₂S levels. Prediction and prevention of H₂S are important in heavy oil production. This will minimize environmental and human health risks, as well as equipment corrosion.