Capture and Sequestration of CO2 Produced by In-Situ Combustion Pilot Project, Orinoco Oil Belt, Venezuela: A Mineral Carbonation Laboratory Assessment

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% CO 2 (g) and 80% N2(g). As an option for Carbon Capture and Storage of produced CO 2 , 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% CO 2 (g) in N 2 (g), as well as pure CO 2 (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 Na 2 CO 3 . Results showed that caustic mud has a CO 2 capture capacity of 7.9 kg CO 2 (g)/m 3 , or 19 kg Na 2 CO 3 /m 3 reaching pH 8.3 at carbonate equilibrium.On the other hand CO 2 capture capacity of the red mud was 87 kg CO 2 (g)/m 3 . Thermogravimetric analysis of red mud (270 -670 °C) shows less than 2% mass loss which is a good indicator of actual CO 2 sequestration. ISCPP will produce around 77000 ton CO 2 (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 CO 2 (g) to be produced in Orinoco Oil Belt, which would diminish as well the hazard of caustic liquor and red mud.

Workflow of the In Situ Combustion EOR Method in Venezuela: Challenges and Opportunities

“…Likewise, efforts should be made to sequester and manage the produced CO 2 . − Perez et al, 2010 proposed a mineral carbonation approach for the ISC pilot project in the FPO, based on caustic byproducts (liquor and red mud) from alumina production. Additionally, EOR projects could be focused on other deposits where previous studies have indicated the technical feasibility of application, but because they did not have enough source of CO 2 they were not applied (e.g., reservoirs in the North Monagas area). − CO 2 could also be injected into aquifers, in this sense feasibility studies have been carried out in deposits of the gas area of Anaco -Venezuela. , …”