Excessive Amount Of Asphaltene Deposition Essay - 1205 Words

An excessive amount of asphaltene deposition may result in a severe formation damage and sometimes blocking the flow path as seen in Figure 6c. Therefore, the injected solvent cannot further diffuse deep into the matrix (due severe to asphaltene deposition) and eventually causes injectivity problem. In this study, C5 injection resulted in the high amount of asphaltene deposition in porous media (11.4 % per Figure 7) and it could block the main flow path, the fracture (as seen in Figure 6c). The pressure profiles of C5 injection shown in Figure 8 can also explain the formation damage caused by severe asphaltene deposition. At early time-stage of solvent injection, solvent mainly diffuses into the oil within the fracture path (while diffusing into the matrix as well) and recovered most of the oil in this area (up to 80 minutes in Figure 8). Thereafter, the solvent is occupied the whole fracture and due to the concentration gradient between the solvent and matrix’s oil, the solve nt diffused into the matrix, dilute the oil by precipitation and deposition of asphaltene. Continuing solvent injection resulted in more asphaltene deposition in the matrix and especially fracture-matrix interface (where the highest concentration gradient is) that eventually cause the formation damage and reduce the injectivity. This can be seen in Figure 7 from time 90 minutes to 280 minutes where the injection pressure increased until the time that was no injection at all (after about 280 minutes).