Systems and methods for backflushing a riser transfer pipe

A system for pumping material from a sea floor, the system comprising:

• a subsea production tool to collect material on the sea floor;
• a vessel positioned on the sea surface in communication with the subsea production tool to receive the material collected by the subsea production tool;
• a riser attached to the vessel and extending toward the sea floor;
• a lift pump in communication with the riser and the subsea production tool to pump the material collected on the sea floor to the vessel via the riser;
• and
• a riser transfer pipe connecting the subsea production tool and the lift pump;
• the lift pump comprising:
• a slurry inlet line attached to the riser transfer pipe;
• a slurry return line attached to the riser;
• a pump chamber between the slurry inlet line and the slurry return line to pump the material from the riser transfer pipe into the riser via the slurry inlet line and the slurry return line;
• a seawater supply line in fluid communication with the pump chamber to provide seawater to power the pump chamber;
• a backflush valve between the slurry inlet line and the seawater supply line to selectively allow fluid communication between the slurry inlet line and the seawater supply line so that seawater can enter the slurry inlet line and riser transfer pipe to backflush the riser transfer pipe.