Experimental Measurements of Bitumen–Water Aquathermolysis during a Steam-Injection Process

Laboratory studies and pilot project tests have shown that appreciable amounts of H2S and CO2 could be generated as a result of the aquathermolysis reaction between bitumen and steam or hot water during thermal recovery operations. A detailed experimental study was carried out to investigate the H2S generation mechanism that occurs during the recovery processes. A laboratory setup was designed and assembled that allowed for aquathermolysis tests to be carried out under controlled pressure conditions and at temperatures to 250 °C. Aquathermolysis tests on a defined ratio of bitumen and water sample were carried out at 225 and 245 °C over 3, 10, and 30 day reaction periods. Phase sampling and analysis procedures were developed to quantify the amount of H2S and CO2 generated during the individual vapor and aqueous phases. Vapor- and liquid-phase composition and bitumen properties, including viscosity and density, were analyzed after each reaction. The results of the investigation showed that the amount of H2S and CO2 generated increased with the reaction time and temperature and the CO2 concentration tended to flatten out over the test period. Data generated during the study were used to develop a kinetic model on a laboratory scale for predicting the time and temperature effects on H2S and CO2 production during the bitumen–steam/hot water aquathermolysis.