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Abstract
The In Situ Combustion Pilot Project (ISCPP) is an ongoing testing effort aimed at assessing the efficacy of this thermal process to increasing recovery factor in the exploitation of heavy oil reservoirs from Orinoco Oil Belt (Venezuela). The process is expected to produce 3 to 7 million cubic feet/d of combustion gases, with an anticipated composition of 20% CO2(g) and 80% N2(g). As an option for Carbon Capture and Storage of produced CO2, mineral carbonation in caustic byproducts (liquor and red mud) from alumina production was assessed at lab scale. Byproducts were characterized showing pH values 12 - 14 and important quantities of NaOH. Caustic liquor and red mud were exposed to gas blends (ambient pressure and temperature) with 10 and 20% CO2(g) in N2(g), as well as pure CO2(g), until reaching pressure stabilization into liquid-gas system. Red mud suspensions with various densities were exposed as well to gas blends during several cycles. Saturation point was reached when consumption of NaOH was completed, resulting in the precipitation of Na2CO3. Results showed that caustic mud has a CO2 capture capacity of 7.9 kg CO2(g)/m3, or 19 kg Na2CO3/m3 reaching pH 8.3 at carbonate equilibrium. On the other hand CO2 capture capacity of the red mud was 87 kg CO2(g)/m3. Thermogravimetric analysis of red mud (270 - 670 °C) shows less than 2% mass loss which is a good indicator of actual CO2 sequestration. ISCPP will produce around 77000 ton CO2(g) in 3 years of operation, and caustic liquor from alumina process will have sufficient capacity for its complete capture. Results revealed the existence of an important sink for CO2(g) to be produced in Orinoco Oil Belt, which would diminish as well the hazard of caustic liquor and red mud.