Collaborative applications include considerable processes that are either implicit, or integrate existing processes. The discovery and the explanation of these processes are becoming increasingly important. This paper is a contribution to these problems. Generally, workflow mining proposes techniques to acquire a workflow model from a workflow log. In this paper, we present a new workflow mining technique to discover workflow patterns. This technique combines complementarily an algorithmic and a statistical analysis technique. This combination can deal with some ambiguities that the single use of the statistical analysis technique cannot resolve.