Bypass valve for gas lift plunger

Details Bypass valve for gas lift plunger Bypass valve for gas lift plunger

1998-10-01

2001-01-23

Neuder, William (Department: 3672)

Wells

With below and above ground modification

Eduction pump or plunger in well

C166S105000, C166S108000, C166S333100

Reexamination Certificate

active

06176309

ABSTRACT:

TECHNICAL FIELD
The present invention relates to plunger lift systems for oil and gas wells, and more particularly to a pressure sensitive bypass valve for a gas lift plunger.
BACKGROUND ART
Plunger lift systems are artificial lift systems for oil and gas wells that are used during the producing life of the well when the bottom hole pressure and the gas to liquid ratio will no longer support natural flow. A plunger lift system includes a tubing string in the well casing with a well valve and lubricator at the top and a spring assembly at the bottom, and a plunger in the tubing string. The well is intermitted by shutting in the well for a selected time period to allow pressure build up and then opening the well valve for a selected period of time, allowing fluid to flow into the sales line. The plunger moves up the tubing string during the time the well valve is open and prevents liquid fall back. When the well valve is closed the plunger falls back to the bottom of the tubing string. The open and closed times for the well valve are usually controlled by a programmable controller.
Plungers are designed to seal against the interior of the tubing string during the ascent from the bottom of the well to maximize the liquid produced during the well valve open period. The plunger seal inhibits the rate of descent of the plunger back to the bottom of the well. Prior known devices, such as the plunger disclosed in U.S. Pat. No. 5,253,713 to Gregg et al., have a rod extending from the top of the plunger that opens a bypass valve that allows fluid flow through the hollow interior of a plunger. The bypass valve allows faster descent of the plunger. The rod in these prior known devices opens the valve when the rising plunger pushes with the rod against a bumper pad in the top of the lubricator. In this type of device, if the well valve is closed before the plunger reaches the top, the bypass valve does not open and the plunger descends slowly. If the controller opens the well valve before the plunger reaches the bottom of the well and the plunger surfaces without liquid on top of the plunger, the plunger could be damaged, the lubricator could be damaged and the entire wellhead could be blown off.
U.S. Pat. No. 5,427,504 to Dinning et al. discloses a plunger bypass valve with a ball shaped closure member and a spring loaded rod activator that pushes the ball into a valve seat to close the valve. This device opens the valve after the plunger reaches the lubricator at the top of the well and the pressures above and below the plunger are equalized.
DISCLOSURE OF THE INVENTION
A plunger for an oil or gas well with an internal bypass valve is disclosed. The plunger has a hollow plunger body, a fishing neck attached to the upper end of the plunger body and a valve attached to the lower end of the plunger body. The valve has a piston biased by a spring to an open position that allows fluid to flow through the plunger and thereby increases the velocity of the plunger during the down stroke. A rod attached to and extending downwardly from the valve piston is pushed upward and moves the valve piston to a closed position when the plunger contacts the spring assembly at the bottom of the well. Opening the well at the top reduces the pressure above the plunger and the plunger travels up the well. The higher pressure below the plunger that pushes the plunger up also keeps the valve piston in the closed position. The spring moves the valve piston to the open position when the pressure difference between the bottom of the plunger and the top of the plunger falls below a selected value. The valve opens without requiring the plunger to strike a bumper at the top of the well or reach the top of the well and without requiring equalization of the pressures above and below the plunger, thereby reducing the risk of damage to the plunger and the well.


REFERENCES:
patent: 1905058 (1933-04-01), Ricker
patent: 2661024 (1953-12-01), Knox
patent: 4848454 (1989-07-01), Spears
patent: 5253713 (1993-10-01), Gregg et al.
patent: 5427504 (1995-06-01), Dinning et al.
patent: 5462115 (1995-10-01), Belden et al.
patent: 6045335 (2000-04-01), Dinning

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