METHODS OF ESTABLISHING AND/OR MAINTAINING FLOW OF HYDROCARBONS DURING SUBSEA OPERATIONS

摘要

Methods are disclosed of establishing and maintaining flow of hydrocarbon-bearing fluid from a subsea source while controlling or limiting hydrocarbon gas hydrate formation in a riser and a collection tool fluidly connected to a distal end of the riser during subsea positioning of the riser and tool. Riser sections are connected at or near the sea surface, and a collection tool may be connected to the distal end of the riser at the surface or picked up subsea by the riser. The riser and tool are deployed subsea near a subsea source of hydrocarbons. A low-density fluid is forced down the riser and tool, and then the riser and tool are positioned to collect hydrocarbons from the subsea source of hydrocarbons. Flow of a low-density fluid is gradually reduced to initiate flow of hydrocarbons up the tool and riser.