A method and apparatus for cleaning a fluid conduit in a hydrocarbon production installation. The method comprises providing a composite pipe having a cleaning head coupled to a first end, and introducing the first end of the composite pipe and the cleaning head into a fluid conduit to be cleaned. Fluid is circulated between an annulus between an interior wall of the fluid conduit and the composite pipe, through a fluid circulation path defined by the cleaning head. The method comprises running the first end of the composite pipe and the cleaning head into the fluid conduit and cleaning at least one substance from the fluid conduit. An aspect of the invention relates to methods comprising circulating a heavy fluid through the fluid circulation path to reduce the effective weight of the pipe in the fluid conduit, and another aspect relates to a method comprising generating at least one pressure pulse in fluid in the fluid circulation path while imparting a pulling force or a pushing force on the pipe.