Methods and systems for circulating fluid within the annulus of a flexible pipe riser

A system for use in an offshore hydrocarbon production facility, comprising:

• a. at least one subsea umbilical tube terminating at a production platform or offshore vessel and at a subsea location for conveying a fluid;
• b. at least one flexible pipe riser terminating at the production platform or offshore vessel and at the subsea location, wherein the flexible pipe riser includes an annulus in fluid communication with the at least one umbilical tube;
• c. end fittings at each terminal location of the flexible pipe riser, wherein each end fitting comprises a port in fluid communication with the annulus;
• d. a connector for placing the at least one umbilical tube in fluid communication with the port of the end fitting at the subsea location;
• and
• e. a pump for pumping fluid to circulate the fluid within a closed loop comprising the annulus and the at least one umbilical tube.

A method for retrofitting a riser system in an existing offshore hydrocarbon production facility, comprising:

• a. disconnecting from a topsides venting system a port of an existing topsides end fitting of a flexible pipe riser including an annulus, wherein the flexible pipe riser has a topsides end fitting and a subsea end fitting having a venting port check valve in fluid communication with the annulus;
• b. removing the venting port check valve from the subsea end fitting;
• c. providing a recirculation kit on the production platform or offshore vessel, the recirculation kit comprising:
• i. a fluid storage tank having a tank inlet and a tank outlet;
• ii. a pump having a pump inlet in fluid communication with the tank outlet and a pump outlet;
• and
• iii. piping for fluid connection between the tank outlet and the pump inlet;
• d. connecting the port of the flexible pipe riser topsides end fitting to the recirculation kit;
• e. connecting a subsea end of an umbilical tube to a port in the subsea end fitting of the flexible pipe riser;
• and
• f. connecting a topsides end of the umbilical tube to the recirculation kit thereby establishing a closed loop including the annulus, the umbilical tube and the recirculation kit.