For routine and special core analysis, first we plugged cores for removing oil, water, evaporates, drilling mud and other contaminants and then washed with solvents and dried out. The common washing for some cores is that, they do not wash part of evaporates, asphaltenes, surfactants or drilling materials in the rock samples. Without removing these contaminants, the porosity and permeability calculated from these rock samples are not precise at all. In case of washing samples, there is always a problem in conducting tests on cores in laboratories. In this research, we tried to minimize the possible damages in this process by detecting a sample with predominant clay minerals based on X-Ray Diffraction (XRD) test and Cation Exchange Capacity (CEC) test of the samples, then washing with 3 different solvents by Soxhlet extractor. Finally, we, measured the strength of the wettability changes of each sample. This can be evaluated with Zeta potential test. After providing SEM and microscopic images, we compared the damages to each other. Then with the EDS test, we investigated the removal of the elements in the sample by its solvent. In this study, different solvents were tested on clay minerals with the aim of identifying the effect of these solvents and comparing the different effects on these samples. Pre- and post- analyzes were performed at optimal conditions for washing and drying.