Recovering used subsea pipelines

Abstract

A method of recovering a used pipeline from the seabed to the surface comprises attaching a recovery cap to the pipeline at the seabed to surround an end of the pipeline, and then upending at least an end portion of the pipeline underwater suspended beneath the recovery cap. While the upended pipeline is being lifted toward the surface, hydrocarbon contaminants rising buoyantly from the interior and walls of the pipeline are captured within the recovery cap, floating on water within and surrounding the pipeline. The captured contaminants are then conveyed from the recovery cap to a reservoir that is external to the recovery cap. The reservoir can be lifted toward the surface with the upended pipeline, for example, on a lifting line attached to the recovery cap. The reservoir can expand as it fills with contaminants and as hydrostatic pressure decreases, with gas from the contaminants being vented off.

Dependencies are inferred from the claim text.