Chemical removal of organic precipitates deposition from porous media: Characterizing adsorption and surface properties

Abstract

The destructive effects of oil-based mud (OBM) on the laboratory and operating conditions are substantial. The result of this damage leads to a drop in oil production by reducing porosity and absolute and relative permeability. In the drilling process, the oil-wetting behavior of the wellbore brings about a lack of proper bonding between cement and the borehole. In the laboratory, these impairments also cause errors in the RCAL and SCAL test results. In this study, calcite samples aged with oil-base drilling mud were washed with various chemical solvents to remove damage induced on the surface properties of the rock. Then, experiments such as FTIR, Zeta, SEM, EDS, and contact angle measurements were performed and these tests indicate the cleaning ability of each solvent on each sample. The results of the FTIR test showed that TL + M, DCM + E, CF + E, THF + M, THF + E solvents had the greatest efficiency in eliminating both polar and nonpolar compounds. The zeta potential test showed that the two solvents DCM + E, TL + M removed more negative charges from the rock surface than other solvents. In SEM imaging, the solvents TL + M, THF + M, THF + P and DCM + E provided better cleaning of the rock surface. Also, the EDS test introduces THF + M, DCM, DCM + E, TL + M solvents as a strong solvent in removing deposits from the OBM. Regarding the contact angle test, the solvents DCM + E and TL + M obtained the highest reduction in the contact angle of the oil drop on the rock surface. All experiments showed that polar and nonpolar compounds should be eliminated in order to restore physical (solid components of the mud) and chemical (wettability alteration) damage. This is accomplished by pure solvents with polar and nonpolar abilities such as dichloromethane. The use of polar/non-polar combination solvents can also be very effective, provided that these two solvents do not form stable bonds with each other.