Experimental study on the mechanism of carbon dioxide removing formation paraffin deposits

• We propose a new method of removing formation paraffin deposits by injecting CO2.
• We discuss the mechanisms of CO2-mediated removal of formation paraffin deposits.
• We carry out an experiment of the CO2-mediated removal of paraffin deposits.

Formation paraffin deposits cause serious productivity damage during the process of oil production. As an effective, economical and environmentally friendly organic solvent, CO2 has many advantages in removing formation paraffin deposits. In this paper, the mechanism of action for CO2-mediated removal of formation paraffin deposits is analysed. An indoor simulation of CO2-mediated removal of formation paraffin deposits is conducted. The feasibility of removing formation paraffin deposits by CO2 is investigated and the effect of injection parameters on plug removal efficiency is discussed. The experimental results show that CO2 adsorption-induced swelling and paraffin thermal expansion are the main factors that facilitate CO2-mediated removal of formation paraffin deposits. Plug removal using CO2 requires a long injection time. As the injection temperature increases, plug removal efficiency increases. As the injection pressure increases, plug removal efficiency first increases and then decreases, which allows for determination of the optimal injection pressure.