The literature did provide insight into four possible damage mechanisms, namely: (1) precipitation of reservoir mineral in the vicinity around the producing well as carbon dioxide escapes from the water phase due to pressure draw down; (2) plugging of reservoir interstices by insoluble organic solids precipitated as the carbon dioxide dissolves in crude oil; (3) formation of an immobile gas phase, predominately CO/sub 2/, which would drastically lower the effective permeability to oil and, especially water; and (4) dissolution of cementation, especially carbonates or feldspars, that could allow fines to migrate in the reservoir and plug tiny flow passages. Each of these mechanisms was investigated in depth during the laboratory experiments. Occasional reports from industry suggested that the use of carbon dioxide to enhance the recovery of tertiary oil might be causing formation damage. This project was undertaken to define the mechanisms responsible for such occurrences. The objectives were threefold: (1) provide a comprehensive literature survey to elicit all that is currently known or suspected, relative to formation damage that might occur during the injection of carbon dioxide into an oil reservoir; (2) under simulated reservoir conditions, demonstrate in the laboratory each of the damage mechanisms and quantify the degree to which each mechanism could cause damage; and (3) for those damage mechanisms identified to be significant, develop a feasible remedy, easily applied in actual field operations. The third mechanism, related to the presence of an immobile gas phase, is a real problem but not unique to the injection of carbon dioxide. In the case of carbon dioxide, the damage should be self-correcting, as the solubility of carbon dioxide in water will eventually allow the water to dissolve away the gas and, hence, the blocking effect.
