Flaring a sour gas is one of the most important considerations in the offshore production platforms and Mobile Offshore Drilling and Production Units (MODPU). The biggest issue occurs in the early stage of heavy oil processing – where the amount of produced gas is fairly low and the gas contains a large amount of carbon dioxide, nitrogen and hydrogen sulfide, without enough flammable components and heat content for immediate and direct flaring. There are several common methods to increase the flammability, with a more common solution being propane injection into the produced gas stream. However in continuous operation, the annual cost becomes prohibitive. In addition, the storage space required for the large amount of propane needed for monthly consumption requires special weight and special considerations for offshore platforms. In this article, a new approach to flaring the sour gas by blending the gas with fuel and injecting the mixture into a fired heater will be presented. By using this approach, the sour produced gas becomes a secondary fuel source (with the primary fuel such as natural gas, diesel or crude oil) and burns in the combustion chamber of a fired heater or furnace. The exhaust is then vented as a flue gas. As a result, the flare system will be used only at well test procedure or start-up condition, with the propane system being a more normal size instead of the much larger one originally required. Also the overall weight of rig, propane cylinder storage space and transportation issues will be reduced.

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