Autonomous optimization of single-well and multi-well gas lift

Patent metadata

Field	Value
Publication number	US-2021198988-A1
Application number	US-201916727718-A
Country	US
Kind code	A1
Filing date	Dec 26, 2019
Priority date	Dec 26, 2019
Publication date	Jul 1, 2021
Grant date	—

Abstract

Methods and systems are provided for controlling gas lift in at least one production well, which determine a quadratic function that relates flow rate or value of oil produced from a production well to gas flow rate for gas injected into the production well based on flow rate measurements for gas injected into the production well and corresponding flow rate measurements of oil produced from the production well. The quadratic function is used to determine an optimal flow rate for gas injected into the production well. The optimal flow rate for gas injected into the production well is used to control the flow rate of gas injected into the production well, and an oil flow rate produced from the production well is measured at the optimal gas flow rate for iterative processing to refine the quadratic function and determination of optimal gas flow rate if need be.

First claim

What is claimed is:

1 . A method for controlling gas lift in at least one production well, comprising:
i) determining a quadratic function that relates oil flow rate produced from a production well to gas flow rate for gas injected into the production well based on flow rate measurements for gas injected into the production well and corresponding flow rate measurements of oil produced from the production well; ii) using the quadratic function to determine an optimal flow rate for gas injected into the production well; and iii) using the optimal flow rate for gas injected into the production well to control the flow rate of gas injected into the production well, and measuring an oil flow rate produced from the production well at the optimal flow rate of gas injected into the production well.

2 . A method according to claim 1 , further comprising:
repeating the operations of i) to iii), wherein for one or more iterations of i) to iii), the quadratic function of i) is based on the measurement of oil flow rate in the previous iteration of iii).

3 . A method according to claim 2 , wherein:
the measurement of oil flow rate in the previous iteration of iii) replaces a data point used to determine the quadratic function in the previous iteration of iii) and preserves non-monotonicity of the quadratic function.

4 . A method according to claim 2 , wherein:
the operations of i) to iii) are repeated for one or more iterations until a predetermined criterion is satisfied.

5 . A method according to claim 1 , wherein:
the quadratic function relates oil flow rate produced from the production well to injected gas flow rate for gas injected into the production well.

6 . A method according to claim 1 , wherein:
the quadratic function relates oil flow rate produced from the production well to shifted gas flow rate for gas injected into the production well, wherein shifted gas flow rate is based on injected gas flow rate less a threshold gas flow rate.

7 . A method according to claim 1 , wherein:
the optimal flow rate for gas injected into the production well as determined in ii) is based on coefficients of the quadratic function.

8 . A method according to claim 1 , wherein:
the operations of i) are performed separately for a plurality of production wells to determine a corresponding plurality of quadratic functions, wherein each quadratic function relates oil flow rate produced from one of the plurality of production wells to gas flow rate for gas injected into that one production well; the operations of ii) use the plurality of quadratic functions to determine optimal flow rates for gas injected into each one of the plurality of production wells; and the operations of iii) use the plurality of optimal flow rates for gas injected into plurality of the production wells to control the flow rate of gas injected into the plurality of production wells, and measure oil flow rates produced from the plurality of production wells at the optimal flow rates of gas injected into the plurality of production wells.

9 . A method according to claim 8 , wherein:
the optimal flow rate for gas injected into at least one of the plurality of production wells as determined in ii) is based on coefficients of the quadratic function for the corresponding production well.

10 . A method according to claim 8 , wherein:
the optimal flow rate for gas injected into at least one of the plurality of production wells as determined in ii) is based on a constraint.

11 . A method according to claim 10 , wherein:
the constraint is based on a total available flow rate of injected gas from a common gas source shared by the plurality of production wells.

12 . A method according to claim 10 , wherein:
the constraint is based on a threshold rate of injected gas for at least one production well.

13 . A method according to claim 10 , wherein:
the optimal flow rates for gas injected into the plurality of production wells as determined in ii) is based on a system of nonlinear equations solved by a sequential quadratic programming (SQP) solver.

14 . A method according to claim 1 , wherein:
the quadratic function of i) relates oil flow rate produced from the production well to gas flow rate for gas injected into the production well at standard conditions.

15 . A system for controlling gas lift in at least one production well, comprising:
a first flow meter for measuring flow rate of gas injected into a production well; a control valve for controlling flow rate of gas injected into the production well; a second flow meter for measuring flow rate of oil produced from the production well; and a controller, operably coupled to the first flow meter, the control valve, and the second flow meter, wherein the controller is configured to:
i) determine a quadratic function that relates oil flow rate produced from a production well to gas flow rate for gas injected into the production well based on flow rate measurements for gas injected into the production well performed by the first flow meter and corresponding flow rate measurements of oil produced from the production well performed by the second flow meter;
ii) use the quadratic function to determine an optimal flow rate for gas injected into the production well; and
iii) use the optimal flow rate for gas injected into the production well to control the control valve to control the flow rate of gas injected into the production well, and obtain a measurement of oil flow rate produced from the production well at the optimal flow rate of gas injected into the production well performed by the second flow meter.

16 . A system according to claim 15 , wherein:
the controller is further configured to repeat the operations of i) to iii), wherein for one or more iterations of i) to iii), the quadratic function of i) is based on the measurement of oil flow rate performed by the second flow meter in the previous iteration of iii).

17 . A system according to claim 16 , wherein:
the controller is further configured such that the measurement of oil flow rate in the previous iteration of iii) replaces a data point used to determine the quadratic function in the previous iteration of iii) and preserves non-monotonicity of the quadratic function.

18 . A system according to claim 16 , wherein:
the controller is further configured to repeat the operations of i) to iii) for one or more iterations until a predetermined criterion is satisfied.

19 . A system according to claim 15 , wherein:
the quadratic function relates oil flow rate produced from the production well to injected gas flow rate for gas injected into the production well.

20 . A system according to claim 15 , wherein:
the quadratic function relates oil flow rate produced from the production well to shifted gas flow rate for gas injected into the production well, wherein shifted gas flow rate is based on injected gas flow rate less a threshold gas flow rate.

21 . A system according to claim 15 , wherein:
the controller is further configured such that the optimal flow rate for gas injected into the production well as determined in ii) is based on coefficients of the quadratic function.

22 . A system according to claim 15 , wherein:
the first flow meter, the control valve, and the second flow meter are provided separately for a plurality of production wells; the controller is operably coupled to the first flow meter, the control valve, and the second flow meter

Assignees

• Schlumberger Technology Corp

Inventors

• Ramakrishnan Terizhandur S
• Bailey William J
• Rashid Kashif

Classifications

• G01F1/74 Primary

  Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid · CPC title

• E21B43/122 Primary

  Gas lift · CPC title

• E21B2200/20

  Computer models or simulations, e.g. for reservoirs under production, drill bits · CPC title

• G01F1/78

  Direct mass flowmeters · CPC title

• E21B44/06

  in response to the flow or pressure of the motive fluid of the drive · CPC title