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Customer: International energy company
Location: Eagle Ford Shale, South Texas, United States
Working with sour gas wells poses a number of challenges. In addition to the risks to
humans, the significant amounts of hydrogen sulfide (H2S) contained in sour gas are
damaging to pipes. Because coiled tubing can be corroded by the sour environment,
H2S-inhibiting additives are required to protect the pipe. Trican Well Service uses a
chemical specifically designed to inhibit corrosion that results from metal exposure to
gaseous or dissolved H2S and/or CO2. This product, called H2S Inhibitor SC (sulfide cracking), is a liquid, organic film-forming corrosion inhibitor that is also oil-soluble and
Corrosion inhibitors are, however, expensive, and the extra chemical requirement and handling come with extra costs. This additional cost is substantial, therefore, Trican performed a study to re-evaluate the amount of chemicals needed for every job.
Current suggested loadings are approximately 227 L (60 gal) each of H2S Inhibitor SC and AI-9 per 24-h period. In addition to extra chemical handling, this means a substantial extra cost. After re-evaluating the necessary chemical loadings, Trican determined that it could limit the chemical loadings, depending on the well conditions. A distinction was made between wells above and below 100°C (212°F). The wells within the Eagle Ford coiled tubing operations are predominately above 100°C (212°F), with H2S concentrations of 20 ppm or less. For these wells, the chemical loadings are added every hour. This equates to loadings of 10 L (2.5 gal) H2S Inhibitor and 10 L (2.5 gal) of the acid inhibitor AI-10 every hour per 10 bbl, which is significantly less than the current loadings. For wells where the temperature is below 100°C (212°F), the load is added once every four hours. The AI products are used with H2S Inhibitor SC as a dispersant. AI-10 (AI-9 can also be used) increases dispersibility. H2S Inhibitor SC is supplied in 200-L (50 gal) drums and can be added directly to water or oil.
The Trican Advantage
Using H2S Inhibitor SC has many advantages. The inhibitor extends the life of metal goods, such as coiled tubing and production tubing, when operating in sour environments. The inhibitor is specifically designed to prevent sulfide stress cracking, is dispersible in mineral acid solutions and brines, and soluble in hydrocarbons. Most importantly, defining the required amount of H2S Inhibitor SC according to the well results in a considerable reduction of chemical usage and costs.