Web Services are becoming the prominent paradigm for distributed computing and electronic businesses. This makes natural the extension of the concepts at the base of the workflow management systems to coordinate network services supplied by many organisations, in order to develop and realise B2B architectures. In this context, the Web Services technology provides the base to make complex business processes through the composition of Web Services (Web Services orchestration and choreography). This paper introduces the current state of the research in this area, and, with reference to the most used Web Service orchestration language (BPEL4WS), introduces a methodology in order to find, through the analysis of different workflows, parts of workflow characterised by Web Services which interact according to a determined model of interaction, in order to obtain a common target. Moreover, we present the ARCOS (Automatic Reusable COmponent Search) Tool which implements the proposed methodology, and, we show its application to a realistic case study.