Method, device, and system for determining water or liquid in the annulus of a flexible riser or flowline

A method for determining whether liquid enters a subsea system comprising a flow line having an inside bore capable of carrying producing fluids from a subsea wellhead to a floating production storage and offloading vessel (FPSO), wherein an annulus is defined between an innermost sheath that surrounds the inside bore and an outermost sheath at the exterior of the flow line, the method comprising:

• disposing a housing element comprising an open-ended tube within and along the length of the annulus and in hydraulic communication with the annulus;
• disposing a sensor element within and along the length of the open-ended tube;
• determining environmental characteristics of the annulus based on measurements made by the sensor element;
• and
• determining at least one of the presence, location, and rate of collection of liquids in the subsea system based on the environmental characteristics of the annulus.

A system for determining whether liquid enters a subsea system, the system comprising:

• a flow line coupled from a subsea wellhead to a floating production storage and offloading vessel (FPSO), wherein the flow line comprising an inside bore capable of carrying producing fluids from a subsea wellhead to FPSO, wherein an annulus defined between an innermost sheath that surrounds the inside bore and an outermost sheath at the exterior of the flow line;
• a plurality of open-ended tubes disposed within and along the length of the annulus and in hydraulic communication with the annulus;
• wherein the plurality of open-ended tubes run to a plurality of pre-determined locations within the annulus;
• a plurality of fiber optic pressure sensors disposed in proximity of the open end of the plurality of open-ended tubes, wherein at least one fiber optic pressure sensor is disposed within and along the length of each of the plurality of open-ended tubes;
• a plurality of connecting fibers disposed within the plurality of open-ended tubes and spliced to the fiber optic pressure sensors;
• and
• data acquisition equipment coupled to the plurality of connecting fibers, wherein the data acquisition equipment is capable of:
• determining environmental characteristics of the annulus based on measurements made by the sensor element, and
• determining at least one of the presence, location, and rate of collection of liquids in the subsea system based on the environmental characteristics of the annulus.