Pumps – Drilled well free piston-type pump
Reexamination Certificate
2002-08-02
2003-12-30
Freay, Charles G. (Department: 3746)
Pumps
Drilled well free piston-type pump
C092S172000, C166S153000, C403S278000
Reexamination Certificate
active
06669449
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a gas lift plunger assembly for use in a gas-producing well and, more particularly, is concerned with pad plunger assembly with one-piece locking end members.
2. Description of the Prior Art
Gas-producing wells typically employ a plunger disposed within tubing of the well and capable of traveling vertically in the tubing as the well is cycled between shut-in and opened conditions in a manner well-known to one of ordinary skill in the art. The plunger is freely movable vertically in the well tubing and is adapted to rise vertically under the force of sufficient gas pressure to drive or lift the plunger and a slug of liquid, such as oil, above it to the surface while isolating the base of the liquid slug from the gas which lifts the plunger. The plunger falls by gravity back down the tubing of the well after the slug of liquid has been delivered to the surface and the gas pressure in the well tubing has decreased due to the transmission of gas from the well tubing to a suitable storage location.
One prior art plunger assembly, called a pad plunger, includes an elongated rigid non-flexible central rod or mandrel and a pair of end members attached to the opposite ends of the mandrel. The end members of the plunger have larger diameters than the mandrel and are internally threaded to permit their removable attachment to the externally threaded opposite ends of the mandrel.
From the foregoing description, it is readily apparent that the pad plunger is made up of an assembly of various parts. It is very important to lock the end members on the plunger so that the pad plunger does not come apart while in the well. The cost of retrieving the plunger parts from the well can range from $1000 to $5000 not including lost production.
Drawbacks exist, however, with the above-described prior art plunger in the manner used to lock the end member on the mandrel. Locking subassemblies
10
, such as the one shown in
FIG. 1
, that have been used are very labor intensive and have required numerous parts, namely, a locking ball
12
and one or more, usually three, locking rings
14
per plunger. The plunger mandrel
16
and end member
18
have to be drilled to provide a hole
20
extending through the side of the end member
18
and into the mandrel
16
so that the locking ball
12
, such as ⅜ inch in diameter, can be dropped in the hole
20
and then the locking ring
14
applied about an annular recess
22
in the end member
18
so as to overlie the hole
20
and retain the ball
12
in the hole. The presence of the ball
12
in the hole
20
prevents the end member
18
from turning and unthreading from the threaded end of the mandrel
16
. However, corrosion problems typically occur behind the rings. Over a short period of time the rings become loose causing premature plunger wear. Therefore, the locking rings are being welded in addition to being crimped, adding more time for labor.
Consequently, a need still exists for an innovation which will provide a solution to the aforementioned problems in the prior art without introducing any new problems in place thereof.
SUMMARY OF THE INVENTION
The present invention provides a pad plunger assembly with one-piece locking end members designed to satisfy the aforementioned need. The solution of the present invention to the aforementioned problems is to provide one-piece locking end members with features which require less labor usage and eliminate multiple parts.
Accordingly, the present invention is directed to a pad plunger assembly which comprises: (a) an elongated central mandrel having a pair of opposite ends with fastening elements thereon; (b) a pair of annular collars each attached to and extending about the mandrel inwardly adjacent to one of the opposite ends thereof, each of the collars having formed therein a plurality of recesses circumferentially spaced from one another about the collar; (c) a pair of end members each having an inner end with an interior bore and fastening elements therein and being removably fastened to one of the opposite ends of the mandrel; and (d) a pair of inner annular flanges each attached to and extending axially from the inner end of one of the end members and adapted to be received over one of the collars such that, for locking the end members onto the mandrel, the end members are fastened onto the opposite ends of the mandrel and then the annular flanges are crimped so as to force circumferentially displaced portions thereof into the recesses of the collars thereby locking the end members in place on the opposite ends of the mandrel such that the end members cannot then be unfastened from the mandrel nor become loosened over time.
More particularly, the mandrel is an elongated rigid non-flexible solid rod. The collars are integrally connected to the mandrel. Each of the inner annular flanges is integrally attached to the inner end of one of the end members. The fastening elements on the ends of the mandrel are external threads. The fastening elements in the interior bores of the end members are internal threads which threadably receive the external threads on the ends of the mandrel when the end members are fastened thereon. The mandrel, collars, end members and flanges are made of a metal.
Also, the assembly includes at least one subassembly of spring-loaded interlocking pad sections disposed about the mandrel and extending over the mandrel between the collars.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
REFERENCES:
patent: 598700 (1898-02-01), Edwards
patent: 1108313 (1914-08-01), Anderson
patent: 1643119 (1927-09-01), Hartman
patent: 2633808 (1953-04-01), Webber
patent: 2919167 (1959-12-01), Taylor, Jr.
patent: 2997964 (1961-08-01), Taylor, Jr.
patent: 3209660 (1965-10-01), Taylor, Jr.
patent: 3372649 (1968-03-01), Webber
patent: 3385222 (1968-05-01), Gregston
patent: 3424066 (1969-01-01), Moore, Jr.
patent: 5372488 (1994-12-01), Turner
patent: 5427504 (1995-06-01), Dinning et al.
patent: 6045335 (2000-04-01), Dinning
patent: 6275556 (2001-08-01), Kinney et al.
Flanagan John R.
Flanagan & Flanagan
Freay Charles G.
LandOfFree
Pad plunger assembly with one-piece locking end members does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pad plunger assembly with one-piece locking end members, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pad plunger assembly with one-piece locking end members will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3175665