Formation damage due to asphaltene deposition in oil reservoir is an issue for many countries that can have strong effect on oil production during heavy oil recovery, miscible flooding, and even primary recovery. Many tests were performed by researchers to determine the amount of deposition and reduction of permeability but the boundaries in which the asphaltene deposited in oil or at the pore surface are not determined.
In this paper, series of tests are performed in order to determine the effect of asphaltene deposition on sandstone rock. Assuming negligible change of viscosity due to various concentrations of asphaltene added, results of laboratory tests performed using pre-separated asphaltene contents from crude oil are showed, to be sure that the first stage (if we divide it into precipitation from liquid phase and deposition on pore surface) of depositing is passed, n-hexane used to flocculate asphaltene particles. To generate reliable data on formation permeability damage due to asphaltene deposition, several dynamic displacement experiments with oil asphaltene content were conducted in various rates and concentrations.
These laboratory tests have shown evidence of core damage happening under dynamic flowing conditions. Data were plotted in order to determine the effect of permeability reduction with comparison to reference oil permeability. It shows a significant permeability reduction after flooding. The results have shown that removal and deposition processes occurred simultaneously and trends were similar to previous works where they follow a straight-line pattern except where removal occurs. The previous available models on CMG roughly matched the data.
The test results and data can be used in formation damage due to asphaltene deposition models for matching and checking models available in literature and commercial softwares.