The ability to create the project team and manage their knowledge is commonly recognized as one the most important quality of the knowledge and innovative organization. The management of knowledge and skills, as well as the management of project competencies has turned out to be essential factors influencing performance of project process. In the paper, the authors present the method and tools for competence modelling for project knowledge management. Basing on this and also using a fuzzy competence model the cost estimation model in the form of a group competences expansion algorithm is proposed. The model focuses on the cost of project team competence expansion caused by the project development process.