Back allocation method

Abstract

The present invention relates inter alia to a method for determining at least one hydrocarbon fluid flow rate, QiHC, of at least one of a plurality of wells connected to a common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells and to adapt at least one operating parameter of at least one well of the plurality of wells. The method comprises the step of receiving comingled-flow measurement data from at least one sensor. Moreover, the method comprises the step of accessing historical well test data, of the ones of the plurality of wells, wherein the well test data are derived from past well tests at the ones of the plurality of wells.

1 . A method for determining at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of a plurality of wells connected to a common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells and to adapt at least one operating parameter of at least one well of the plurality of wells, the method comprising the following steps:
 receiving comingled-flow measurement data from at least one sensor, wherein the comingled-flow measurement data are representative of a comingled hydrocarbon fluid flow rate, Q field   HC ;   accessing historical well test data, wherein the well test data are representative of test hydrocarbon fluid flow rates, Q i   test HC , of the ones of the plurality of wells, wherein the well test data are derived from past well tests at the ones of the plurality of wells;   determining based on Lagrange multipliers, at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of the plurality of wells using the received comingled-flow measurement data and the accessed historical well test data, and   adapting at least one operating parameter of at least one well of the plurality of wells, wherein adapting is at least partially based on the at least one determined hydrocarbon fluid flow rate, Q i   HC , of the at least one of the plurality of wells.   
     
     
         2 . A method for determining at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of a plurality of wells connected to a common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells, the method comprising the following steps:
 receiving comingled-flow measurement data from at least one sensor, wherein the comingled-flow measurement data are representative of a comingled hydrocarbon fluid flow rate, Q field   HC ;   accessing historical well test data, wherein the well test data are representative of test hydrocarbon fluid flow rates, Q i   test HC , of the ones of the plurality of wells, wherein the well test data are derived from past well tests at the ones of the plurality of wells;   determining, based on Lagrange multipliers, at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of the plurality of wells using the received comingled-flow measurement data and the accessed historical well test data.   
     
     
         3 . The method according to  claim 1 , wherein the comingled-flow measurement data are further representative of at least one of the following: a comingled gas flow rate, Q field   Gas , and a comingled water flow rate, Q field   Water . 
     
     
         4 . The method according to  claim 1 , wherein the well test data are further representative of at least one of the following: test gas-to-hydrocarbon-fluid ratios, GOR i   test , and test water-to-hydrocarbon-fluid ratios, WOR i   test , of the ones of the plurality of wells. 
     
     
         5 . The method according to  claim 1 , further comprising
 identifying the ones of the plurality of wells for which the difference between the at least one determined hydrocarbon fluid flow rate, Q i   HC , and the respective test hydrocarbon fluid flow rate, Q i   test HC , exceeds a predefined threshold value.   
     
     
         6 . The method according to  claim 1 , wherein determining the at least one hydrocarbon fluid flow rate, Q i   HC , comprises using at least one uncertainty value for at least one of the plurality of wells, wherein preferably the at least one uncertainty value is at least partially based on a measurement error of the well test data. 
     
     
         7 . The method according to  claim 1 , wherein determining the at least one hydrocarbon fluid flow rate, Q i   HC , of the at least one of the plurality of wells is based on a Lagrangian function that comprises at least one objective function and at least one constraint function, wherein the Lagrangian function optionally comprises two objective functions and at least two constraint functions, wherein the Lagrangian function further optionally comprises at least three objective functions and at least three constraint functions, wherein the Lagrangian function even further optionally comprises exactly three objective functions and exactly three constraint functions. 
     
     
         8 . The method according to  claim 7 , wherein the Lagrangian function comprises a hydrocarbon fluid flow rate objective function, wherein the hydrocarbon fluid flow rate objective function is configured to minimize the difference between a well specific hydrocarbon fluid flow rate, Q i   HC , and a respective well specific test hydrocarbon fluid flow rate, Q i   test HC , wherein the difference may be minimized for each well, and wherein optionally the hydrocarbon fluid flow rate objective function comprises the sum of the squared differences of each well's hydrocarbon fluid flow rate, Q i   HC , and the respective test hydrocarbon fluid flow rate, Q i   test HC . 
     
     
         9 . The method according to  claim 7 , wherein the Lagrangian function comprises a gas-to-hydrocarbon-fluid ratio objective function, wherein the gas-to-hydrocarbon-fluid ratio objective function is configured to minimize the difference between a well specific gas-to-hydrocarbon-fluid ratio, GOR i , and a respective well specific test gas-to-hydrocarbon-fluid ratio, GOR i   test , wherein the difference may be minimized for each well, and wherein optionally the gas-to-hydrocarbon-fluid ratio objective function comprises the sum of the squared differences of each well's gas-to-hydrocarbon-fluid ratio, GOR i , and the respective test gas-to-hydrocarbon-fluid ratio, GOR i   test . 
     
     
         10 . The method according to  claim 7 , wherein the Lagrangian function comprises a water-to-hydrocarbon-fluid ratio objective function, wherein the water-to-hydrocarbon-fluid ratio objective function is configured to minimize the difference between a well specific water-to-hydrocarbon-fluid ratio, WOR i , and a respective well specific test water-to-hydrocarbon-fluid ratio, WOR i   test , wherein the difference may be minimized for each well, and wherein optionally the water-to-hydrocarbon-fluid ratio objective function comprises the sum of the squared differences of each well's water-to-hydrocarbon-fluid ratio, WOR i , and the respective test water-to-hydrocarbon-fluid ratio, WOR i   test . 
     
     
         11 . The method according to  claim 7 , wherein the Lagrangian function comprises a hydrocarbon fluid flow constraint function being multiplied with a hydrocarbon fluid flow Lagrange multiplier, wherein the hydrocarbon fluid flow constraint function optionally comprises the difference between the comingled hydrocarbon fluid flow rate, Q field   HC , and the sum of hydrocarbon fluid flow rates, Q i   HC , of the ones of the plurality of wells. 
     
     
         12 . The method according to  claim 7 , wherein the Lagrangian function comprises a gas flow rate constraint function being multiplied with a gas flow rate Lagrange multiplier, wherein the gas flow rate constraint function optionally comprises the difference between the comingled gas flow rate, Q field   Gas , and the sum of hydrocarbon fluid flow rates, Q i   HC , of the ones of the plurality of wells, wherein each hydrocarbon fluid flow rate, Q i   HC , of the ones of the plurality of wells is multiplied with a respective gas-to-hydrocarbon-fluid ratio, GOR i . 
     
     
         13 . The method according to  claim 7 , wherein the Lagrangian function comprises a water flow rate constraint function being multiplied with a water flow rate Lagrange multiplier, wherein the water flow rate constraint function optionally comprises the difference between the comingled water flow rate, Q field   Water , and the sum of hydrocarbon fluid flow rates, Q i   HC , of the ones of the plurality of wells, wherein each hydrocarbon fluid flow rate, Q i   HC , of the ones of the plurality of wells is multiplied with a respective water-to-hydrocarbon-fluid ratio, WOR i . 
     
     
         14 . The method according to  claim 1 , wherein the comingled-flow measurement data are representative of the comingled hydrocarbon fluid flow rate, Q field   HC , the comingled gas flow rate, Q field   Gas , and the comingled water flow rate, Q field   Water . 
     
     
         15 . The method according to  claim 1 , wherein the well test data are representative of test hydrocarbon fluid flow rates, Q i   test HC , test gas-to-hydrocarbon-fluid ratios, GOR i   test , and test water-to-hydrocarbon-fluid ratios, WOR i   test , of the ones of the plurality of wells. 
     
     
         16 . The method according to  claim 1 , wherein the step of determining further comprises determining gas-to-hydrocarbon-fluid ratios, GOR i , and/or water-to-hydrocarbon-fluid ratios, WOR i , of individual ones of the plurality of wells. 
     
     
         17 . A system for determining at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of a plurality of wells connected to a common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells, the system comprising:
 a data storing means configured to:
 store historical well test data, wherein the well test data are representative of test hydrocarbon fluid flow rates, Q i   test HC , of the ones of the plurality of wells, wherein the well test data are derived from past well tests at the ones of the plurality of wells; 
   a data acquisition unit configured to:
 receive comingled-flow measurement data, wherein the comingled-flow measurement data are representative of a comingled hydrocarbon fluid flow rate, Q field   HC ; and 
 access historical well test data from the data storing means; and 
   an optimizer unit being able to receive data from the data acquisition unit, the optimizer unit configured to:
 determine, based on Lagrange multipliers, at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of the plurality of wells using the received comingled-flow measurement data and the accessed historical well test data. 
   
     
     
         18 . The system according to  claim 17 , wherein the well test data are further representative of at least one of test gas-to-hydrocarbon-fluid ratios, GOR i   test , and test water-to-hydrocarbon-fluid ratios, WOR i   test , of the ones of the plurality of wells. 
     
     
         19 . The system according to  claim 17 , wherein the comingled-flow measurement data are further representative of at least one of the following: a comingled gas flow rate, Q field   Gas , and a comingled water flow rate, Q field   Water . 
     
     
         20 . The system according to  claim 17 , wherein the system further comprises
 a signal transmission unit being configured for adapting at least one operating parameter of at least one well of the plurality of wells, wherein adapting is at least partially based on the at least one determined hydrocarbon fluid flow rate, Q i   HC , of the at least one of the plurality of wells.   
     
     
         21 . The system according to  claim 17 , wherein the system further comprises
 means for identifying the ones of the plurality of wells for which the difference between the at least one determined hydrocarbon fluid flow rate, Q i   HC , and the respective test hydrocarbon fluid flow rate, Q i   test HC , exceeds a predefined threshold value.   
     
     
         22 . The system according to  claim 17 , wherein determining the at least one hydrocarbon fluid flow rate, Q i   HC , comprises using at least one uncertainty value for at least one of the plurality of wells, wherein preferably the at least one uncertainty value of the ones of the plurality of wells is at least partially based on a measurement error of the well test data of the ones of the plurality of wells. 
     
     
         23 . The system according to  claim 17 , wherein the comingled-flow measurement data are representative of the comingled hydrocarbon fluid flow rate, Q field   HC , the comingled gas flow rate, Q field   Gas , and the comingled water flow rate, Q field   Water . 
     
     
         24 . The system according to  claim 17 , wherein the well test data are representative of test hydrocarbon fluid flow rates, Q i   test HC , test gas-to-hydrocarbon-fluid ratios, GOR i   test , and test water-to-hydrocarbon-fluid ratios, WOR i   test , of the ones of the plurality of wells. 
     
     
         25 . A computer program, comprising instructions that when carried out by at least one processor, cause the at least one processor to perform for performing a method accruing to  claim 1 . 
     
     
         26 . A non-transitory computer readable medium having stored thereon software instructions that, when carried out by at least one processor, cause the processor to perform for performing a method accruing to  claim 1 . 
     
     
         27 . A control unit for determining at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of a plurality of wells connected to a common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells, the control unit comprising at least one processor and a memory coupled with the at least one processor; the at least one processor and memory configured to perform a method accruing to  claim 1 . 
     
     
         28 . An oilfield comprising a plurality of wells connected to a common pipeline and a control unit for determining at least one hydrocarbon fluid flow rate, Q i   HC , of at least one of the plurality of wells connected to the common pipeline with a comingled hydrocarbon fluid flow from the plurality of wells, the control unit comprising at least one processor and a memory coupled with the at least one processor; the at least one processor and memory configured to perform a method accruing to  claim 1 , such that the control unit is configured to perform the method accruing to  claim 1 .