The use of tracers to monitor transport processes is a generic and versatile technique with a range of applications. In the subsurface domain, inter-well tracer testing has been used in more than 1000 injectors to monitor water and gas flooding worldwide the last 2-3 decades and has been used to map well-to-well communication and sweep and as a means to improve reservoir understanding. Recent tracer technology development, including new interpretation methodologies and access to a wide range of new tracers, has further strengthened this application of tracers. In this presentation, the status of tracer technology will be briefly reviewed. Recent improvements, including partitioning tracers will also be presented. Case studies that apply these methodologies will be highlighted. Operational challenges and pitfalls to avoid will also be discussed, as well as measures to be taken to assure reliability of the results.
