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BR-112022002374-B1 - METHODS FOR CONTROLLING A COMPRESSOR SYSTEM FOR GAS LIFTING OPERATIONS

BR112022002374B1BR 112022002374 B1BR112022002374 B1BR 112022002374B1BR-112022002374-B1

Abstract

AUTOMATED METHOD FOR GAS LIFTING OPERATIONS. The present invention relates to a compressor system suitable for performing artificial gas lifting operations in an oil or gas well. A method for controlling the compressor system is also disclosed. The disclosed methods provide the well operator with the ability to identify and maintain gas injection rates that result in the minimum production pressure. The minimum production pressure will be determined either by a bottom borehole sensor or by a casing pressure sensor located on the surface or in any convenient location capable of monitoring the pressure at the wellhead.

Inventors

  • BROOKS MIMS TALTON III
  • Aaron Baker
  • Eric Perry
  • Paul Munding
  • JOHN D. HUDSON

Assignees

  • FLOGISTIX, LP

Dates

Publication Date
20260310
Application Date
20200819
Priority Date
20190830

Claims (20)

  1. 1. Method for controlling a compressor system (10) for gas lifting operations characterized in that it comprises the steps of: operating the compressor system (10) at an initial gas injection rate sufficient to lift all the liquids from the well; operating the compressor system (10) for a first incremental time period at a first incremental gas injection rate, wherein said first incremental gas injection rate is either greater than the initial gas injection rate or less than the initial gas injection rate; continuing to produce liquids from the well during the first incremental period while monitoring the production pressure within the well; determining the average production pressure over the first incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, operating the compressor system (10) for a second incremental time period at a second incremental gas injection rate, wherein the second incremental gas injection rate is greater than the first incremental gas injection rate, or when said second incremental gas injection rate is greater than the first incremental gas injection rate. If the gas injection rate is less than the first incremental gas injection rate, operate the compressor system (10) for a second incremental time period at a second incremental gas injection rate, where the second incremental gas injection rate is less than the first incremental gas injection rate; continue to produce liquids from the well during the second incremental period while monitoring the production pressure within the well; determine the average production pressure during the second incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, operate the compressor system (10) for a third incremental time period at a third incremental gas injection rate where the third incremental gas injection rate is greater than the second incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, operate the compressor system (10) for a third incremental time period at a third incremental gas injection rate, where the third incremental gas injection rate is less than the second incremental gas injection rate; continue to produce well liquids during the third incremental period while monitoring the production pressure within the well; determine the average production pressure during the third incremental period; identify the incremental gas injection rate that produces the lowest production pressure while discharging all fluids from the well; adjust the identified incremental gas injection rate as an operational gas injection rate for the compressor system (10) and operate the compressor system (10) to produce all fluids from the well; where each incremental period lasts between 24 hours and 72 hours.
  2. 2. Method according to claim 1, characterized in that it further comprises the steps of: when the first incremental gas injection rate is greater than the first gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is greater than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for the fourth incremental time period at a fourth incremental gas injection rate, wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; and determining the average production pressure during the fourth incremental period.
  3. 3. Method according to claim 1, characterized in that it further comprises the steps of: when the first incremental gas injection rate is greater than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate, wherein the fourth incremental gas injection rate is greater than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate, wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; determining the average production pressure during the fourth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate gas, after the fourth incremental period, operate the compressor system (10) for a fifth incremental period at a fifth incremental gas injection rate wherein the fifth incremental gas injection rate is greater than the fourth incremental gas injection rate, or wherein the first incremental gas injection rate is less than the initial gas injection rate and after the fourth incremental period, operate the compressor system (10) for a fifth incremental time period at a fifth incremental gas injection rate wherein the fifth incremental gas injection rate is less than the fourth incremental gas injection rate; continue to produce liquids from the well during the fifth incremental period, while controlling the production pressure within the well; and determine the average production pressure during the fifth incremental period.
  4. 4. Method according to claim 1, characterized in that it further comprises: when the first incremental gas injection rate is greater than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is greater than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; determining the average production pressure during the fourth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, after The fourth incremental period, operate the compressor system (10) for a fifth incremental period at a fifth incremental gas injection rate where the fifth incremental gas injection rate is greater than the fourth incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the fourth incremental period, operate the compressor system (10) for a fifth incremental time period at a fifth incremental gas injection rate where the fifth incremental gas injection rate is less than the fourth incremental gas injection rate; continue to produce liquids from the well during the fifth incremental period while monitoring the production pressure within the well; determine the average production pressure during the fifth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, after the fifth incremental period, operate the compressor system (10) for a sixth incremental time period at a sixth incremental gas injection rate where the sixth incremental gas injection rate is greater than the fifth incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the fifth incremental period, operate the compressor system (10) for a sixth incremental time period at a sixth incremental gas injection rate, wherein the sixth incremental gas injection rate is less than the fifth incremental gas injection rate; continue to produce liquids from the well during the sixth incremental period, while controlling the production pressure within the well; and determine the average production pressure during the sixth incremental period.
  5. 5. Method according to claim 1, characterized in that the increase or decrease in the gas injection rate during the first, second and third incremental periods is from 566 to 2265 m3/day (20 mscfd to 80 mscfd).
  6. 6. Method, according to claim 1, characterized in that it further comprises the step of recording well conditions of fluid flow rates, gas production rate and gas injection rate that produces the lowest average production pressure during incremental periods.
  7. 7. Method according to claim 1, characterized in that the incremental period lasts between 36 hours and 60 hours.
  8. 8. Method, according to claim 1, characterized in that it further comprises the steps of: estimating a maximum out-of-well fluid flow rate (qmax) and an average reservoir pressure (P) at the maximum out-of-well fluid flow rate; measure the production pressure using a bottom hole sensor or measure the surface casing pressure using a surface sensor and calculate the production pressure; calculate the total gas injection rate required to discharge all fluids from the wellbore using the measured or calculated production pressure and the estimated qmax and P values; compare the calculated total gas injection rate with the gas injection rate that produces the lowest production pressure while discharging all fluids from the well, if the calculated total gas injection rate is within the tolerance range of the gas injection rate that produces the lowest production pressure while discharging all fluids from the well, then adjust the qmax and P values as static values for calculating the minimum gas injection rate required to discharge the well of all liquids; calculate the minimum gas injection rate required to discharge the well of all liquids; and direct the compressor system (10) to operate at the calculated minimum gas injection rate.
  9. 9. Method according to claim 8, characterized in that the step of calculating the minimum gas injection rate required to discharge the well of all liquids further comprises the steps of: monitoring the fluid flow rates of water, gas, and oil out of the well; monitoring the bottomhole pressure or calculating the bottomhole pressure using a monitored casing surface pressure; calculating the total gas flow rate required to transport all fluids out of the well; subtracting the gas flow rate out of the well from the calculated total gas flow rate required to transport all fluids out of the well to provide the minimum gas injection rate required to discharge the well of all liquids; and operating the compressor system (10) at the minimum gas injection rate required to discharge the well of all liquids.
  10. 10. Method according to claim 9, characterized in that it further comprises the step of comparing the critical gas injection rate with the gas flow rate out of the well and ceasing operation of the compressor system (10) when the critical gas injection rate is less than the gas flow rate out of the well.
  11. 11. Method, according to claim 1, characterized in that the step of determining the average production pressure during the first incremental period occurs during the last 85% to 95% of the first incremental period, wherein the step of determining the average production pressure during the second incremental period occurs during the last 85% to 95% of the second incremental period, and wherein the step of determining the average production pressure during the third incremental period occurs during the last 85% to 95% of the third incremental period.
  12. 12. Method for controlling a compressor system (10) for gas lifting operations characterized in that it comprises: operating the compressor system (10) at an initial gas injection rate sufficient to lift all the liquids from the well; operating the compressor system (10) for a first incremental period of time at a first incremental gas injection rate, wherein the first incremental gas injection rate is either greater than the initial gas injection rate, or less than the initial gas injection rate; continuing to produce liquids from the well during the first incremental period while monitoring the production pressure within the well; determine the average production pressure over the first incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, operate the compressor system (10) for a second incremental time period at a second incremental gas injection rate where the second incremental gas injection rate is less than the first incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, operate the compressor system (10) for a second incremental time period at a second incremental gas injection rate where the second incremental gas injection rate is less than the first incremental gas injection rate; continue to produce liquids from the well during the second incremental period while monitoring the production pressure within the well; determine the average production pressure during the second incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate, operate the compressor system (10) for a third incremental time period at a third injection rate incremental gas injection wherein the third incremental gas injection rate is less than the second incremental gas injection rate, or wherein the first incremental gas injection rate is less than the initial gas injection rate, operate the compressor system (10) for a third incremental time period at a third incremental gas injection rate wherein the third incremental gas injection rate is less than the second incremental gas injection rate; continue to produce liquids from the well during the third incremental period while monitoring the production pressure within the well; determine the average production pressure during the third incremental period; identify the incremental gas injection rate that produces the lowest production pressure while discharging all fluids from the well; and adjust the identified incremental gas injection rate as an operational gas injection rate for the compressor system (10) and operate the compressor system (10) to produce all fluids from the well; wherein each incremental period lasts between 24 hours and 72 hours.
  13. 13. Method according to claim 12, characterized in that it further comprises the steps of: when the first incremental gas injection rate is less than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; and determining the average production pressure during the fourth incremental period.
  14. 14. Method according to claim 12, characterized in that it further comprises the steps of: when the first incremental gas injection rate is greater than the initial gas injection rate and after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; determining the average production pressure during the fourth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate and after the fourth incremental period, operate the compressor system (10) for a fifth incremental period at a fifth incremental gas injection rate where the fifth incremental gas injection rate is less than the fourth incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the fourth incremental period, operate the compressor system (10) for a fifth incremental time period at a fifth incremental gas injection rate, where the fifth incremental gas injection rate is less than the fourth incremental gas injection rate; continue to produce liquids from the well during the fifth incremental period, while monitoring the production pressure within the well; and determine the average production pressure during the fifth incremental period.
  15. 15. Method according to claim 12, characterized in that it further comprises: When the first incremental gas injection rate is greater than the initial gas injection rate, after the third incremental period, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate, operating the compressor system (10) for a fourth incremental time period at a fourth incremental gas injection rate wherein the fourth incremental gas injection rate is less than the third incremental gas injection rate; continuing to produce liquids from the well during the fourth incremental period while monitoring the production pressure within the well; determining the average production pressure during the fourth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate and after the fourth period incremental, operate the compressor system (10) for a fifth incremental time period at a fifth incremental gas injection rate where the fifth incremental gas injection rate is less than the fourth incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the fourth incremental period, operate the compressor system (10) for a fifth incremental time period at a fifth incremental gas injection rate, where the fifth incremental gas injection rate is less than the fourth incremental gas injection rate; continue to produce liquids from the well during the fifth incremental period, while monitoring the production pressure within the well; determine the average production pressure during the fifth incremental period; when the first incremental gas injection rate is greater than the initial gas injection rate and after the fifth incremental period, operate the compressor system (10) for a sixth incremental period at a sixth incremental gas injection rate where the sixth incremental gas injection rate is less than the fifth incremental gas injection rate, or when the first incremental gas injection rate is less than the initial gas injection rate and after the fifth incremental period, operate the compressor system (10) for a sixth incremental time period at a sixth incremental gas injection rate, wherein the sixth incremental gas injection rate is less than the fifth incremental gas injection rate; continue to produce liquids from the well during the sixth incremental period while monitoring the production pressure within the well; and determine the average production pressure during the sixth incremental period.
  16. 16. Method according to claim 12, characterized in that the increase or decrease in the gas injection rate during the first, second and third incremental periods is from 566 to 2,265 m3/day (20 mscfd to 80 mscfd).
  17. 17. Method according to claim 12, characterized in that it further comprises the step of recording well conditions of fluid flow rates, gas production rate and gas injection rate that produces the lowest average production pressure during incremental periods.
  18. 18. Method according to claim 12, characterized in that the incremental period lasts between 36 hours and 60 hours.
  19. 19. Method according to claim 12, characterized in that it further comprises the steps of: estimating a maximum out-of-well fluid flow rate (qmax) and an average reservoir pressure (P) at the maximum out-of-well fluid flow rate; measuring the production pressure using a bottomhole sensor or measuring the surface casing pressure using a surface sensor and calculating the production pressure; calculating the total gas injection rate required to discharge all fluids from the wellbore using the measured or calculated production pressure and the estimated values of qmax and P; comparing the calculated total gas injection rate with the gas injection rate that produces the lowest production pressure while discharging all fluids from the well; if the calculated total gas injection rate is within the tolerance range of the gas injection rate that produces the lowest production pressure while discharging all fluids from the well, then setting the values of qmax and P as static values for calculating the minimum gas injection rate required for discharge the well of all liquids; calculate the minimum gas injection rate required to discharge the well of all liquids; and direct the compressor system (10) to operate at the calculated minimum gas injection rate.
  20. 20. Method according to claim 19, characterized in that the step of calculating the minimum gas injection rate required to discharge the well of all liquids further comprises the steps of: monitoring the fluid flow rates of water, gas, and oil out of the well; monitoring the bottomhole pressure or calculating the bottomhole pressure using a monitored surface casing pressure; calculating the total gas flow rate required to transport all fluids out of the well; subtracting the gas flow rate out of the well from the calculated total gas flow rate required to transport all fluids out of the well to provide the minimum gas injection rate required to discharge the well of all liquids; and operating the compressor system (10) at the minimum gas injection rate required to discharge the well of all liquids.

Description

CROSS-REFERENCE TO RELATED ORDERS [001] This application claims priority over U.S. Provisional Application No. 62/893,976 filed on August 30, 2019. BACKGROUND [002] The use of injected gas, commonly known as gas lift, to assist in the production of liquids from a well is a balancing act. Over-injecting gas will ensure the lift of liquids to the surface, but will increase friction during the production process and may reduce the flow of fluid from the formation to the well. Under-injecting gas will fail to lift liquids to the surface and will result in a buildup of liquids in the well, further restricting fluid flow and production loss. Thus, the industry would benefit from methods and devices capable of continuously managing the gas injection rate to compensate for changes in production pressure. SUMMARY OF THE INVENTION [003] In one aspect, the present disclosure provides a method for controlling a compressor system for gas lifting operations. The method includes the steps of: [004] operate the compressor system at an initial gas injection rate sufficient to lift all the liquids from the well; [005] operate the compressor system for an initial period of time with a first incremental gas injection rate higher than the initial gas injection rate; [006] continue to produce liquids from the well during the first incremental period while monitoring the production pressure inside the well; [007] determine the average production pressure during the incremental period; [008] operate the compressor system during the second incremental time period at a second incremental gas injection rate where the second incremental gas injection rate is greater than the first incremental gas injection rate; [009] continue to produce liquids from the well during the second incremental period while monitoring the production pressure inside the well; [0010] determine the average production pressure during the second incremental period; [0011] operate the compressor system for a third incremental time period at a third incremental gas injection rate where the third incremental gas injection rate is greater than the second incremental gas injection rate; [0012] continue to produce liquids from the well during the third incremental period while monitoring the production pressure within the well; [0013] determine the average production pressure during the third incremental period; [0014] identify the incremental gas injection rate that produces the lowest production pressure while discharging all fluids from the well; and [0015] Adjust the Operating Gas Injection Rate for the compressor system and operate the compressor system to produce all fluids from the well. [0016] The method described may include additional incremental periods with higher gas injection rates. [0017] Alternatively, the step of operating the compressor system for a first incremental period at an incremental gas rate higher than the initial gas injection rate is replaced by a step that occurs for a first incremental period at an incremental gas rate lower than the initial gas injection rate. Subsequent incremental periods operate with incremental gas injection rates lower than the previous incremental rates. Additional incremental periods may be added with each additional incremental period at a gas injection rate lower than the previous incremental period. [0018] Alternatively, the step of operating the compressor system for a first incremental period at an incremental gas rate higher than the initial gas injection rate is replaced by a step that occurs at an incremental gas rate higher than the initial gas injection rate, and subsequent incremental periods occur at incremental gas injection rates lower than the first incremental gas injection rate. Additional incremental periods may be added, with each additional incremental period at a gas injection rate lower than the previous incremental period. [0019] Alternatively, the step of operating the compressor system for an initial incremental period at an incremental gas rate higher than the initial gas injection rate is replaced by a step that occurs at an incremental gas rate lower than the initial gas injection rate. Subsequent incremental periods occur at incremental gas injection rates that are higher than the previous incremental gas injection rates. Additional incremental periods may be added to each additional incremental period at a gas injection rate higher than the previous incremental period. [0020] The described method may additionally include steps to determine the critical injection rate. The Critical Rate mode comprises the following steps: [0021] estimate the maximum out-of-well fluid flow rate (qmax) and the average reservoir pressure (P) at the maximum out-of-well fluid flow rate; [0022] measure the production pressure using a bottom bore sensor or by measuring the surface casing pressure using a surface sensor and calculate the production pressure; [0023] calculate the total gas injection rate requ