Casing differential pressure based control method for gas-producing wells

• US 6,196,324 B1
• Filed: 04/12/1999
• Issued: 03/06/2001
• Est. Priority Date: 04/10/1998
• Status: Expired due to Term

• Current Assignee: PCS Ferguson Incorporated (ChampionX Corporation)
• Original Assignee: Bruce M. Victor, Jeff L. Giacomino
• Inventors: Victor, Bruce M., Giacomino, Jeff L.
• Primary Examiner(s): DANG, HOANG C
• Application Number:
  US09/290,040
• Time in Patent Office: 694 Days
• Field of Search: 166/372, 166/370, 166/66.6, 166/65.1, 166/53, 166/250.15, 137/624.2, 137/624.15
• US Class Current: 166/372
• CPC Class Codes: E21B 43/121 Lifting well fluids monitoring of down-hole pump systems E21B47/008
• CPC Class Codes: E21B 47/008 Monitoring of down-hole pump systems, e.g. for the detection of "pumped-off" conditions

Abstract

A casing differential pressure based control method used in conjunction with a gas-producing well includes the steps of sensing current sales line pressure and well casing and tubing pressures and changing or switching an A valve between open and close states based on differences between selected pairs of these current pressures relative to preset minimum differentials between the same pairs of these pressures. Open Differential Pressure determines when to open the A valve and initiate gas sales. Open Differential Pressure is the preset minimum pressure difference by which the casing pressure exceeds the sales line pressure. Close Pressure determines when to close the A valve and terminate gas sales. Close Pressure is the preset minimum pressure of the casing. Once Open Differential Pressure has been reached and the A valve switched to the open state such that gas sales are occurring, the gas sales are allowed to continue as long as the current casing pressure is dropping and until the current casing pressure reverses. When the current casing pressure reverses and rises by the Close Pressure, the A valve is switched to the close state.

Claims

1. A casing differential pressure based control method used in conjunction with a gas-producing well, a casing within the well for receiving a flow of gas under pressure from a production formation, a tubing extending downward within the casing to a lower portion being in communication with the casing for receiving the flow of gas under pressure therefrom, a sales line located outside of the well and connected in flow communication with the tubing for routing the flow of gas under pressure away from the well, an A valve interposed in the sales line and being convertable between open and close states in which flow of gas is correspondingly allowed and blocked from the tubing to the sales line, and an electronic controller connected to the A valve for controlling the cycling of the A valve between open and close states and thereby the well between the open and shut-in conditions in which the gas under pressure flows correspondingly from the tubing and elevates in pressure in the casing, said method comprising the steps of:

(a) sensing the current casing pressure, current tubing pressure and current sales line pressures;

(b) switching the A valve to open state such that gas sales are initiated in response to sensing when the current casing pressure exceeds the current sales line pressure; and

(c) switching the A valve to close state such that gas sales are terminated in response to sensing when the current casing pressure has decreased, reversed and then risen by a preset minimum pressure.

2. The method of claim 1, further comprising:

presetting an Open Differential Pressure equal to a preset minimum pressure difference by which the casing pressure exceeds the sales line pressure.

3. The method of claim 2, further comprising:

calculating the difference between the current casing pressure and current sales line pressure, said switching of the A valve to open state being in response to sensing when the difference between the current casing pressure and current sales line pressure reaches the preset Open Differential Pressure.

4. The method of claim 1, further comprising:

presetting a Close Pressure equal to said preset minimum pressure of the casing.

5. The method of claim 4, further comprising:

sensing the current casing pressure, said switching of the A valve to close state being in response to sensing when the current casing pressure has decreased, reversed and then risen by the preset Close Pressure.

6. A casing differential pressure based control method used in conjunction with a gas-producing well, a casing within the well for receiving a flow of gas under pressure from a production formation, a tubing extending downward within the casing to a lower portion being in communication with the casing for receiving the flow of gas under pressure therefrom, a sales line located outside of the well and connected in flow communication with the tubing for routing the flow of gas under pressure away from the well, an A valve interposed in the sales line and being convertable between open and close states in which flow of gas is correspondingly allowed and blocked from the tubing to the sales line, and an electronic controller connected to the A valve for controlling the cycling of the A valve between open and close states and thereby the well between the open and shut-in conditions in which the gas under pressure flows correspondingly from the tubing and elevates in pressure in the casing, said method comprising the steps of:

(a) presetting an open Differential Pressure equal to a preselected minimum pressure difference by which the casing pressure exceeds the sales line pressure;

(b) presetting a Close Pressure equal to a preselected minimum pressure of the casing;

(c) sensing the current casing pressure and current sales line pressure and calculating the difference between current casing pressure and current sales line pressure;

(d) comparing the difference between the current casing pressure and current sales line pressure to the Open Differential Pressure;

(e) comparing the current casing pressure to the Close Pressure;

(f) in response to sensing when the difference between the current casing pressure and current sales pressure equals the Open Differential Pressure, switching the A valve to the open state such that gas sales are initiated; and

(g) after switching of the A valve to the open state and in response to sensing when the current casing pressure has decreased, reversed and then risen by the Close Pressure, switching the A valve to the close state terminating gas sales such that gas sales thereby are allowed to continue as long as the current casing pressure is dropping and until the casing pressure reverses and then rises by the Close Pressure.

7. A casing differential pressure based control method used in conjunction with a gas-producing well, a casing within the well for receiving a flow of gas under pressure from a production formation, a tubing extending downward within the casing to a lower portion being in communication with the casing for receiving the flow of gas under pressure therefrom, a freely movable plunger disposed in the tubing for traveling vertically relative to the tubing between a lower initial position and an upper terminal position in response to open and shut-in conditions of the casing, a sales line located outside of the well and connected in flow communication with the tubing for routing the flow of gas under pressure away from the well, an A valve interposed in the sales line and being convertable between open and close states in which flow of gas is correspondingly allowed and blocked from the tubing to the sales line, and an electronic controller connected to the A valve for controlling the cycling of the A valve between open and close states and thereby the well between the open and shut-in conditions in which the plunger travels correspondingly upward to the upper terminal position and downward to the lower initial position and the gas under pressure flows correspondingly from the tubing and elevate in pressure in the casing, said method comprising the steps of:

(a) sensing the current casing pressure, current tubing pressure and current sales line pressures;

(b) switching the A valve to open state such that gas sales are initiated in response to sensing when the current casing pressure exceeds the current sales line pressure;

(c) sensing the arrival of the plunger at the upper terminal position; and

(d) after sensing the arrival of the plunger at the upper terminal position, switching the A valve to close state such that gas sales are terminated in response to sensing when the current casing pressure has decreased, reversed and then risen by a preset minimum pressure.

8. The method of claim 7, further comprising:

presetting an Open Differential Pressure equal to a preset minimum pressure difference by which the casing pressure exceeds the sales line pressure.

9. The method of claim 8, further comprising:

calculating the difference between the current casing pressure and current sales line pressure, said switching of the A valve to open state being in response to sensing when the difference between the current casing pressure and current sales line pressure reaches the preset Open Differential Pressure.

10. The method of claim 7, further comprising:

presetting a Close Pressure equal to a preset minimum pressure of the casing.

11. The method of claim 10, further comprising:

said switching of the A valve to close state being in response to sensing when the current casing pressure has decreased, reversed and then risen by the preset Close Pressure.

12. A casing differential pressure based control method used in conjunction with a gas-producing well, a casing within the well for receiving a flow of gas under pressure from a production formation, a tubing extending downward within the casing to a lower portion being in communication with the casing for receiving the flow of gas under pressure therefrom, a freely movable plunger disposed in the tubing for traveling vertically relative to the tubing between a lower initial position and an upper terminal position in response to open and shut-in conditions of the casing, a sales line located outside of the well and connected in flow communication with the tubing for routing the flow of gas under pressure away from the well, an A valve interposed in the sales line and being convertable between open and close states in which flow of gas is correspondingly allowed and blocked from the tubing to the sales line, and an electronic controller connected to the A valve for controlling the cycling of the A valve between open and close states and thereby the well between the open and shut-in conditions in which the plunger travels correspondingly upward to the upper terminal position and downward to the lower initial position and the gas under pressure flows correspondingly from the tubing and elevate in pressure in the casing, said method comprising the steps of:

(a) presetting an Open Differential Pressure equal to a preselected minimum pressure difference by which the casing pressure exceeds the sales line pressure;

(b) presetting a Close Pressure equal to a preselected minimum pressure of the casing;

(c) sensing the current casing pressure and current sales line pressure and calculating the difference between current casing pressure and current sales line pressure;

(d) comparing the difference between the current casing pressure and current sales line pressure to the Open Differential Pressure;

(e) sensing the arrival of the plunger at the upper terminal position;

(f) in response to sensing when the difference between the current casing pressure and current sales line pressure equals the Open Differential Pressure, switching the A valve to the open state such that gas sales are initiated; and

(g) after switching of the A valve to the open state and in response to sensing the arrival of the plunger at the upper terminal position and the rising of current casing pressure by the Close Pressure, switching the A valve to the close state terminating the gas sales such that gas sales thereby are allowed to continue as long as the current casing pressure is dropping and until the casing pressure reverses and then rises by the Close Pressure.