A casing cleaning tool

A well cleaning tool 100 having an elongate body 102 has a central fluid bore 120 and a displaceable or extendable cleaning element 110 with at least one fluid channel 150 in fluid communication with the central fluid bore and extending through the cleaning element in a direction inclined to the longitudinal axis. The cleaning element may be a casing scraper with helical teeth, may be biased outwards by a spring or resilient resin plate 144, and may comprise a drillable or dissolvable material such as a magnesium-based dissolvable material.