Abstract: Packers are expandable sealing devices used to seal off zones in a well. Packers are expanded to seal the bore of the well by means of expansion fluid supplied via individual pipelines. However, packers near the top of the well have to accommodate all of the pipelines for packers below. The invention provides a packer system comprising a plurality of packers (22-28) and fluid delivery means arranged to supply fluid to the packers, to expand them in use. The fluid delivery means includes a common fluid pipeline (36) for the packers. Thus, only one expansion fluid pipeline has to pass through the upper packers (22, 23), irrespective of the overall number of packers in the system.