Pumps – Drilled well free piston-type pump
Reexamination Certificate
1999-02-05
2001-03-13
Freay, Charles G. (Department: 3746)
Pumps
Drilled well free piston-type pump
C417S555200, C092S16200R, C166S153000
Reexamination Certificate
active
06200103
ABSTRACT:
TECHNICAL FIELD
This present invention relates to plunger lift systems for oil and gas wells, and more particularly to gas lift plungers with an improved gas seal.
BACKGROUND ART
Plunger lift systems are artificial lift systems for oil and gas wells. Plunger lift systems 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. The tubing string has a well valve and lubricator at the top and a spring assembly at the bottom, and an elongated cylindrical plunger that travels between the bottom and the top of 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, pushing a liquid slug to the top. 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 typically controlled by a programmable controller.
The gas lift plunger in a plunger lift system is the interface between the liquid slug above the plunger and the pressurized gases that push the plunger from below. Plungers are designed to minimize the downward flow of liquid and the upward flow of gas between the plunger and tubing string as the plunger travels up the tubing string. One type of plunger uses mechanical seals spaced along the cylindrical plunger body to seal between the plunger and the tubing string. U.S. Pat. No. 5,253,713 to Gregg et al. discloses a plunger with elastomeric seals. U.S. Pat. No. 5,427,504 discloses a plunger with sealing pads that are biased outwardly against the tubing string by springs. Plungers with mechanical seals provide efficient sealing between the plunger and the tubing string. However, plungers with mechanical seals have a plurality of parts, often making these plungers complex and expensive. These plungers also often require an internal bypass valve that must be opened for the plunger to fall back to the bottom of the tubing string.
Plungers for plunger lift systems have heretofore used the upward gas flow to seal between the plunger and tubing string. This type of plunger has a diameter slightly smaller than the diameter of the tubing string in order to allow liquid to flow upward between the plunger and tubing string while the well valve is closed. These plungers generally have a plurality of longitudinally spaced circumferential grooves spaced between cylindrical body sections of the peripheral surface of the plunger body. The grooves create a turbulent flow in gases flowing upwardly between the plunger and tubing string as the plunger is pushed up the tubing string, and thereby reduce the gas flow up and liquid flow down around the plunger. Prior known plungers have uniformly sized and uniformly shaped grooves uniformly spaced along the plunger body. The recessed surface of the grooves in the prior known plungers connects to the surface of the plunger body along sharp edges or corners. U.S. Pat. No. 4,410,300 to Yerian discloses a plunger with grooves having an asymmetrical V-shaped cross section. U.S. Pat. No. 4,502,843 to Martin discloses a plunger with grooves having a semi-circular cross section. Plungers having grooves with a square or rectangular cross section have also been produced. Plungers with gas flow seals are less complex and less expensive than plungers with mechanical seals. However, prior known gas flow-seal plungers are less efficient in sealing than plungers with mechanical seals.
DISCLOSURE OF THE INVENTION
A plunger for an oil or gas well is disclosed. The plunger has a cylindrical elongated plunger body with a top end and a bottom end. The plunger body includes a plurality of longitudinally spaced circumferential grooves defined by recessed surfaces interspersed between sections of the peripheral surface of the plunger body. A curved surface or radius connects a lower extent of the recess of each groove to a body section, and a sharp edge or corner connects an upper extent of the surface of the groove to the next higher body section. The cross section of each recess is a continuous curve or a plurality of lines connected by curves. The depth of the recesses decreases from the bottom to the top of the plunger. The length of the body sections between the recesses may also decrease from the bottom to the top of the plunger, thereby decreasing the distance between recesses. The shape, sizing and spacing of the recesses improves plunger lift and reduces the flow of liquid around the plunger.
REFERENCES:
patent: 1922396 (1933-08-01), Ricker
patent: 2276109 (1942-03-01), Smith
patent: 2763017 (1956-09-01), Redin
patent: 3352212 (1967-11-01), Read
patent: 4410300 (1983-10-01), Yerian
patent: 4502843 (1985-03-01), Martin
patent: 4663795 (1987-05-01), Neff
patent: 5253713 (1993-10-01), Gregg et al.
patent: 5427504 (1995-06-01), Dinning et al.
patent: 6038725 (2000-03-01), Knapp
patent: 2051178 (1981-01-01), None
WSPO20 Solid Steel Plunger Drawing.
Catalog Page Brush Plunger, Well Master Corporation, Lakewood, Colorado.
Catalog Page Solid Steel Plunger, Well Master Corporation, Lakewood, Colorado.
Avallone, Eugene et al., ed.; 1987; Marks'Standard Handbook for Mechanical Engineers; pp. 3-58 to 3-59.
Freay Charles G.
Lewis, Jr. Ancel W.
Tyler Cheryl J.
LandOfFree
Gas lift plunger having grooves with increased lift does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas lift plunger having grooves with increased lift, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas lift plunger having grooves with increased lift will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473620