ASPHALTENE PRECIPITATION FOR CO2WAG FLOODING PROCESS: EFFECTS OF OPERATIONAL PARAMETERS ON OIL RECOVERY FACTOR AND PHYSICAL PROPERTIES

CO2-water alternating injection (CO2 WAG) is an advanced recovery strategy widely used in many oil fields. Asphaltenes may precipitate and eventually deposit on the rock surface in CO2 WAG injection, reducing permeability and porosity and thus affecting oil production. This work aims to determine under which operating conditions the highest recovery factor (RF) is reached in a WAG injection process and analyze the behavior of the physical properties of oil and rock, in addition to precipitation and deposition of asphaltenes. The results show that the higher the WAG ratio is, the higher the pressures achieved will be, reducing the amount of precipitated asphaltenes and its deposition. However, as the WAG ratio increases, the water breakthrough occurs earlier, causing the macroscopic displacement efficiency to decrease, impairing oil production. Furthermore, in most cases, higher RFs are reached for intermediate WAG ratios in a given injection cycle.