TECHNOLOGICAL COMPLICATIONS (FORMATION DAMAGE) DURING CO2 INJECTION FOR ENHANCED OIL RECOVERY. Part 2. INTERACTION OF CO2 WITH FORMATION OIL: WETTABILITY CHANGE, ASPHALTENE PRECIPITATION AND DEPOSITION IN THE FORMATION

In the second part of the review (the first part was published in [1]) the processes of formation damage at CO2 injection due to the oil phase stability disturbance are considered. Changes in reservoir temperature, pressure or fluid composition due to CO2 dissolution can provoke asphaltene precipitation and deposition. Their adsorption on the reservoir pore surface leads to a change in decrease in rock permeability. The currently ac wettability and a cepted numerical models describe well the experimental results on colmatation of pore media by asphaltenes in the presence of CO2, with different equations for asphaltene adsorption and kinetics of their occurrence being used in the models. Asphaltenes precipitated in pore volumes migrate with formation fluids to production wells and can form deposits that complicate oil production.