Calibration of in-line monitoring instruments in a subsea installation

Abstract

A method of calibration of an in-line monitoring instrument in a subsea installation ( 6 ), comprises using an umbilical ( 4 ) for transportation of a sample fluid from the subsea installation ( 6 ) to a topside installation ( 2 ) and/or for transportation of a reference fluid from the topside installation ( 2 ) to the subsea installation ( 6 ); comparing measurements of the sample fluid or the reference fluid by the in-line monitoring instrument with measurements of the same fluid obtained previously or subsequently by topside instruments; and adjusting the calibration of the in-line monitoring instrument in the subsea installation ( 6 ), if required, based on the results of the comparison of measurements.

1 - 27 . (canceled) 
     
     
         28 . A method of calibration of an in-line monitoring instrument in a subsea installation, the method comprising:
 using an umbilical for transportation of a sample fluid from the subsea installation to a topside installation and/or for transportation of a reference fluid from the topside installation to the subsea installation;   comparing measurements of the sample fluid or the reference fluid by the in-line monitoring instrument with measurements of the same fluid obtained previously or subsequently by topside instruments; and   adjusting the calibration of the in-line monitoring instrument in the subsea installation, if required, based on the results of the comparison of measurements.   
     
     
         29 . A method as claimed in  claim 28 , wherein a sample fluid is used and the sample fluid is obtained from the subsea installation, transported up the umbilical to the topside installation, and passed to the topside instrument for measurements to be taken. 
     
     
         30 . A method as claimed in  claim 29 , wherein a measurement of the sample fluid or of equivalent fluid is taken by the in-line monitoring instrument at around the same time that the sample is obtained. 
     
     
         31 . A method as claimed in  claim 29 , comprising: measuring a sample of the fluid using the in-line monitoring instrument at the subsea installation, and then transporting the exact same fluid to the topside installation for the comparative measurement to be taken. 
     
     
         32 . A method as claimed in  claim 29 , wherein sample fluid is first measured by the in-line monitoring instrument in the subsea installation and then sampled at a later point, after the fluid has passed through the in-line monitoring instrument. 
     
     
         33 . A method as claimed in  claim 28 , wherein the sample fluid is extracted upstream of the in-line monitoring instrument, the sample fluid is measured at the topside installation after it has been passed upward through the umbilical, and the in-line monitoring instrument measures the same working fluid at a later point. 
     
     
         34 . A method as claimed in  claim 28 , wherein a reference fluid is used and the reference fluid is first measured using a suitable topside instrument, then transported down the umbilical to the subsea installation, and introduced into the in-line monitoring instrument at the subsea installation to thereby enable a measurement of the reference fluid to be obtained for comparison purposes. 
     
     
         35 . A method as claimed in  claim 28 , being used for calibration of multiple in-line monitoring instruments, with the umbilical being used for transportation of multiple sample fluids or reference fluids, each being relevant to a different monitoring instrument. 
     
     
         36 . A method as claimed in  claim 28 , wherein the calibrating step is carried out by a human operator adjusting appropriate settings based on the measured data or based on a comparison of the data produced by the measuring device(s) and/or by a data processing device such as a computer. 
     
     
         37 . A method as claimed in  claim 28 , wherein the calibrating step comprises automated calibration through remote adjustment of the in-line monitoring instrument using a data processing device. 
     
     
         38 . A method as claimed in  claim 28 , wherein the umbilical is provided with one or more sample line(s) for the purpose of transporting the sample or reference fluid, and wherein the sample lines take the form of heated tube bundles. 
     
     
         39 . A method as claimed in  claim 38 , wherein the inner diameter of the sample line(s) is in the range 6 to 20 mm and/or the flow velocity is in the range 0.5 to 60 m/s. 
     
     
         40 . A system for calibration of an in-line monitoring instrument in a subsea installation, the system comprising:
 an umbilical equipped with a sample line for transporting fluid between a subsea installation and a topside installation;   a subsea coupling for connecting the sample line to the subsea installation and enabling extraction or introduction of fluid from or to the subsea installation;   a topside coupling for introduction of fluid to the sample line or extraction of fluid from the sample line; and   one or more measurement device(s) for receiving one or more measurement(s) of the fluid from a topside instrument, receiving one or more measurement(s) of the same or a similar fluid from the in-line monitoring instrument and providing data enabling calibration of the in-line monitoring instrument based on a comparison of the measurements.   
     
     
         41 . A system as claimed in  claim 40 , wherein the measurement device(s) are arranged to provide appropriate data to enable a human operator to compare measurements and determine an appropriate adjustment to calibrate the in-line monitoring instrument. 
     
     
         42 . A system as claimed in  claim 40 , wherein the measurement device(s) are arranged to compare data and optionally to propose an adjustment for calibration of the in-line monitoring instrument. 
     
     
         43 . A system as claimed in  claim 40 , comprising an automatic calibration device for communications with the in-line monitoring instrument and automatic remote calibration thereof, based on data from the measurement device(s). 
     
     
         44 . A system as claimed in  claim 40 , wherein the calibration device communicates with the in-line monitoring instrument via the umbilical. 
     
     
         45 . A system as claimed in  claim 40 , wherein the system is for calibration of multiple in-line monitoring instruments, with the umbilical hence being arranged for transportation of multiple fluids each being relevant to a different monitoring instrument. 
     
     
         46 . A system as claimed in  claim 40 , wherein the umbilical is provided with one or more sample lines for the purpose of transporting the sample fluid or reference fluid, and wherein the sample line(s) are heated tube bundles. 
     
     
         47 . A system as claimed in  claim 46 , wherein the inner diameter of the sample lines is in the range 6 to 20 mm and/or the flow velocity is in the range 0.5 to 60 m/s.