GAS EVOLUTION FROM THE AQUATHERMOLYSIS OF HEAVY OILS

Aquathermolysis experiments were performed on core samples taken from three large bitumen and heavy oil deposits found in Alberta, to invest igate gas evolution over the temperature range 360 to 420-degrees-C. E xperiments conducted on Athabasca included runs with an initially pre- oxidized oil sample and runs with a change in core mineralogy. Pre-oxi dizing the oil was found to substantially increase the amount of carbo n monoxide and molecular hydrogen generated. Core mineralogy played an important role in the generation of carbon dioxide, and the amount of hydrogen sulphide produced was dependent on oil composition, mineralo gy and time. Although substantial amounts of gaseous products are prod uced by simple thermolysis reactions (i.e., without water present), th e main thermal recovery methods, steam injection and in-situ combustio n, bring the oil phase and its host rock into direct contact with wate r. As water has been shown to take part in thermal cracking reactions, these experiments provide usful data for the estimation of produced g as composition during thermal recovery projects.