Method of monitoring the loading of a subsea production system

Abstract

A method of monitoring a condition of a connection between two bodies which are connected using a connector. The connector has a sensor assembly which provides an output representing a degree of movement of one or both of the two bodies. The method includes installing the connector and the two bodies in a use position in which the connector joins the two bodies, and using the output from the sensor assembly and a numerical model to determine a force on one or both of the two bodies or of the condition of the connector. The numerical model is a record of test forces applied to a test element secured to the connector or of a test connector having a same configuration as the connector and a corresponding output from the sensor assembly of the connector or of the test connector during and/or after the application of each test force.

1 : A method of monitoring a condition of a connection between two bodies which are connected using a connector,
 wherein,   the connector comprises a sensor assembly which is operable to provide an output representing a degree of movement of one or both of the two bodies to which the connector is secured,   the method comprising:   installing the connector and the two bodies in a use position in which the connector joins the two bodies; and   using the output from the sensor assembly and a numerical model to determine a force on one or both of the two bodies or of the condition of the connector,   wherein,   the numerical model comprises a record of a plurality of test forces applied to a test element which is secured to the connector or of a test connector having a same configuration as the connector and a corresponding output from the sensor assembly of the connector or of the test connector at least one of during and after the application of each of the plurality of test forces.   
     
     
         2 : The method as recited in  claim 1 , further comprising:
 issuing a warning if the force exceeds a predetermined threshold level.   
     
     
         3 : The method as recited in  claim 1 , wherein the output of the sensor assembly represents at least one of a strain of the connector body and a displacement of one of the two bodies relative to the connector. 
     
     
         4 : The method as recited in  claim 1 , further comprising:
 over time, using forces determined from readings from the sensor assembly at a plurality of different times to obtain an indication of a cumulative force on the connector; and   issuing a warning when the cumulative force exceeds a predetermined cumulative threshold.   
     
     
         5 : The method as recited in  claim 4 , wherein the predetermined threshold level varies in a predetermined manner depending on the cumulative force on the connector. 
     
     
         6 : The method as recited in  claim 1 , wherein the sensor assembly comprises a strain gauge mounted on the connector. 
     
     
         7 : The method as recited in  claim 1 , wherein the sensor assembly comprises a displacement sensor which is configured to measure a linear displacement or an angular displacement of one of the two bodies relative to the connector. 
     
     
         8 : The method as recited in  claim 1 , wherein,
 the two bodies are each a fluid flow body, and   during the installing of the connector and the two fluid flow bodies in the use position in which the connector joins the two fluid flow bodies, the two fluid flow bodies are arranged so that the connector and the two fluid flow bodies enclose a continuous flow passage which extends from one fluid flow body to the other fluid flow body.   
     
     
         9 : The method as recited in  claim 8 , wherein,
 two seals provide a barrier to a flow of a fluid out of the continuous flow passage, the two seals being,
 a primary seal which provides a first barrier preventing a leakage of the fluid out of the continuous flow passage at a joint between the two fluid flow bodies, and 
 a secondary seal which is located at an exterior side of the primary seal, and a seal cavity exists, 
 between the two seals and the two fluid flow bodies, or 
 between the two seals, one or both of the two fluid flow bodies, and the connector. 
   
     
     
         10 : The method as recited in  claim 9 , wherein the sensor assembly comprises a pressure sensor which measures a pressure of the fluid in the seal cavity. 
     
     
         11 : The method as recited in  claim 9 , wherein.
 a piston in a cylinder is fluidly connected to the seal cavity, and   the sensor assembly comprises a displacement sensor which is configured to measure a movement of the piston in the cylinder which is fluidly connected to the seal cavity.   
     
     
         12 : The method as recited in  claim 1 , wherein,
 one of the two bodies has a longitudinal axis, and   each of the plurality of test forces is applied generally parallel to the longitudinal axis at the connection between the two bodies.   
     
     
         13 : The method as recited in  claim 1 , wherein,
 one of the two bodies has a longitudinal axis, and   each of the plurality of the test forces is a bending moment applied generally perpendicular to the longitudinal axis at the connection between the two bodies.   
     
     
         14 : The method as recited in  claim 1 , wherein,
 one of the two bodies has a longitudinal axis, and   each of the plurality of test forces is a torsion applied to rotate the one of the two bodies about its longitudinal axis.   
     
     
         15 : The method as recited in  claim 1 , wherein one or both of the two bodies is a section of a pipeline. 
     
     
         16 : The method as recited in  claim 1 , wherein one or both of the two bodies is,
 a manifold,   a riser,   a flow spool,   an emergency disconnect package,   a subsea tree,   a Christmas tree adapter connector,   a well control package,   a Pig launcher/receiver,   a pipeline end termination,   a pipeline end manifold,   a riser base,   a UTH,   a pump and control system module, or   a subsea storage unit.   
     
     
         17 : A system comprising:
 two bodies;   a connector which connect the two bodies, the two bodies and the connector being located subsea, the connector comprising a sensor assembly which is operable to provide output signals each of which represent a degree of movement of one or both of the two bodies to which the connector is secured;   a data storage apparatus which is connected to and stores the output signals from the sensor assembly; and   a processor which is connected to the data storage apparatus and which is configured to use one of the output signals from the sensor assembly and a numerical model to determine at least one of a force on one or both of the two bodies and a condition of the connector,   wherein,   the numerical model comprises a record of a plurality of test forces applied to a test element which is secured to the connector or of a test connector having a same configuration as the connector and a corresponding output from the sensor assembly of the connector or of the test connector at least one of during and after the application of each of the plurality test forces.   
     
     
         18 : The system as recited in  claim 17 , wherein the processor is further configured to compare one of the output signals from the sensor assembly with the numerical model to determine a load on one or both of the two bodies. 
     
     
         19 : The system as recited in  claim 18 , wherein the processor is further configured compare the output signals from the sensor assembly at a plurality of different times with the numerical model to obtain a data set representing a loading of one of the two bodies over time. 
     
     
         20 : The system as recited in  claim 17 , wherein the processor is at a topside location. 
     
     
         21 : The system as recited in  claim 17 , wherein,
 the processor is a subsea processor, and   the processor is further configured to compare one of the output signals from the sensor assembly with a statistical representation of the numerical model to determine if a loading on one of the two bodies has reached a threshold level.   
     
     
         22 : The system as recited in  claim 21 , wherein the processor is further configured to transmit a warning signal to a topside location or to an ROV/AUV if the loading on one or both or the two bodies has reached the threshold level. 
     
     
         23 : The system as recited in  claim 21 , further comprising:
 a topside processor which is configured to compare one of the output signals from the sensor assembly with the numerical model to determine the loading on one or both of the two bodies.