Analysis of the employees' contacts supports monitoring compliance of the safety and access control policies. The paper presents an approach to the extraction of the different interaction patterns existing between employees belonging to one department or different ones from the access control sensors' logs. Exploration of the possible interaction patterns and their feature selection is done using interactive heat maps and contact graph that allow detection periodical patterns as well as anomalous deviations. The formal model of the established interaction patterns is described. The proposed approach is tested on the VAST MiniChallenge-2 2016 data set, which describes movement of the employees within organization building.