Patent Application
20100037716
The disclosures made herein relate generally to oil field equipment and, more particularly, to a pump jack for reciprocating an oil well pump and to devices configured for allowing adjustability of a polish rod of a pump jack.
Pump jacks, which are also known as beam pumping units, are used for driving reciprocating pumps located downhole in the bore of a subterranean oil wellhead. With respect to a typical arrangement of a pump jack, a string of sucker rods is suspended from a carrier bar of the pump jack.
A polish rod is provided at the top of the string of sucker rods and is connected to the carrier bar. The carrier bar is suspended from the horsehead of the pump jack by a cable bridle. The polish rod is suspended by a polish rod clamp atop the carrier bar or rod-rotator. The polish rod extends through the carrier bar and downwardly through a stuffing box seal at a wellhead. The polish rod is connected to the string of sucker rods and the string of sucker rods extends downhole to a pump within a well-bore casing.
The use of a clamp is a conventional approach for securing the polish rod to the carrier bar in a fixed location with respect to the carrier bar. A conventional polish rod has a substantially smooth exterior surface (e.g., a smooth rod made of steel) and the clamp compressively bears on the exterior surface such that relative movement of the clamp with respect to the polish rod is precluded. Loosening of the clamp allows for vertical adjustment of the polish rod and, thus, the string of sucker rods with respect to the carrier bar. One drawback of such clamp arrangement is that it is difficult to controllably make desired adjustments (e.g., especially small precise adjustments) of the polish rod with respect to the carrier bar.
Therefore, an arrangement for securing the polish rod in a fixed vertical position with respect to the carrier bar while providing for controlled vertical adjustment of the polish rod with respect to the carrier bar would be advantageous, desirable and useful.
Embodiments of the present invention provide an arrangement for securing the polish rod in a fixed vertical position with respect to the carrier bar. More specifically, embodiments of the present invention provide for controlled vertical adjustment of the polish rod with respect to the carrier bar. In doing so, embodiments of the present invention advantageously overcomes one or more shortcomings associated with conventional approaches for securing a polish rod in a fixed position with respect to a carrier bar.
In one embodiment of the present invention, a polish rod apparatus of a pump jack system is adapted for being connected between a motion imparting mechanism of a pump jack and a string of sucker rods. The polish rod apparatus comprises a polish rod and a lift device. The polish rod has a first end portion, a second end portion and a center portion extending between the first and second end portions. The center portion includes a thread structure extending along at least a portion of a length thereof. The first end portion is configured for being connected to the string of sucker rods. The lift device has an adjuster body including a central passage extending therethrough. The central passage of the adjuster body includes a thread structure configured for being matingly engaged with the thread structure of the polish rod such that rotation of the adjuster body relative to the polish rod causes axial movement of the adjuster body along a longitudinal axis of the polish rod thereby enabling vertical adjustment of the sucker rod assembly with respect to the motion imparting mechanism.
In another embodiment of the present invention, a pump jack is configured for driving a pump unit of a subterranean well. The pump jack comprises a sucker rod assembly, a motion imparting mechanism, a polish rod and a lift device. The sucker rod assembly includes a string of sucker rods and a polish rod attachment structure attached to the string of sucker rods. The motion imparting mechanism includes a lift device engaging structure operable to move in opposing vertical directions with respect to a wellhead of the subterranean well. The polish rod has a first end portion, a second end portion and a center portion extending between the first and second end portions. The first end portion of the polish rod is engaged with the polish rod attachment structure of the sucker rod assembly. The center portion includes a thread structure extending along at least a portion of a length thereof. The lift device is coupled between the polish rod and the lift device engaging structure of the motion imparting mechanism. The lift device includes an adjuster body having a central passage extending therethrough. The polish rod extends through the central passage of the adjuster body. The adjuster body includes a thread structure within the central passage thereof threadedly engaged with the thread structure of the polish rod such that rotation of the adjuster body relative to the polish rod causes axial movement of the adjuster body along a longitudinal axis of the polish rod thereby causing vertical adjustment of the sucker rod assembly with respect to the motion imparting mechanism.
In another embodiment of the present invention, a method is configured for adjustably driving a pump unit of a subterranean well. The method comprises a plurality of operations. Operations are performed for disposing a string of sucker rods within a well bore casing of the subterranean well and for attaching an end portion of a polish rod to a polish rod attachment structure of the string of sucker rods. An operation is performed for extending the polish rod through a lift device engaging structure of a motion imparting mechanism from a first side thereof. The motion imparting mechanism includes an apparatus operable to move the lift device engaging structure in opposing vertical directions with respect to a wellhead of the subterranean well. An operation is performed for threadedly engaging a thread structure within a central passage of a lift device with a mating threaded structure of an exterior surface of the polish rod such that the polish rod extends through the central passage and the lift device is coupled between the polish rod and a second side of the lift device engaging structure. Thereafter, an operation is performed for rotating the lift device relative to the polish rod such that rotation of the lift device causes axial movement of the lift device along a longitudinal axis of the polish rod thereby causing vertical adjustment of the string of sucker rods with respect to the lift device engaging structure of the motion imparting mechanism.
These and other objects, embodiments, advantages and/or distinctions of the present invention will become readily apparent upon further review of the following specification, associated drawings and appended claims.
Referring to
Referring now to
The lift device 110 is coupled between the polish rod 108 and the lift device engaging structure 116. The lift device 110 includes an adjuster body 128 having a central passage 130 extending therethrough. The adjuster body 128 includes one or more adjustment wrench engaging features 131 (e.g., holes) on its exterior surface. The polish rod 108 extends through the central passage 130 of the adjuster body 128. The adjuster body 128 includes helical threads 132 thread structure within the central passage 130 threadedly engaged with the helical threads 126 of the polish rod 108. In this manner, rotation of the adjuster body 128 relative to the polish rod 108 causes axial movement of the adjuster body 128 along a longitudinal axis of the polish rod 108 thereby causing vertical adjustment of the sucker rod assembly 104 with respect to the motion imparting mechanism 106. Such vertical adjustment enables a rod pump (e.g., the pump unit 102) to be spaced out properly.
It is disclosed herein that the polish rod 108 can be a multi-piece rod. In one embodiment, a first piece is threaded and a second pieces attached to the first piece is not threaded. The first and second pieces can be fixedly attached to each other or one piece can rotate relative to the other.
As shown in
In operation, the string of sucker rods 112 is disposed within the well bore casing 115 of the subterranean well 103. The first end portion 120 of the polish rod 108 is attached to the polish rod attachment structure 114 of the string of sucker rods 112. The polish rod is extended through the lift device engaging structure 116 of the motion imparting mechanism 100 from its first side. The helical threads 132 within a central passage of the adjuster body 128 are threadedly engaged with the helical threads 126 of the polish rod 108 such that the polish rod 108 extends through the central passage 130 of the adjuster body 128 and the lift device 110 is coupled between the polish rod 108 and a second side of the lift device engaging structure 116. Thereafter, the lift device 110 is rotated relative to the polish rod 108 such that rotation of the lift device 110 causes axial movement of the lift device 110 along the longitudinal axis of the polish rod 108 thereby causing vertical adjustment of the string of sucker rods 112 with respect to the lift device engaging structure 116 of the motion imparting mechanism 100.
In the preceding detailed description, reference has been made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the present invention may be practiced. These embodiments, and certain variants thereof, have been described in sufficient detail to enable those skilled in the art to practice embodiments of the present invention. It is to be understood that other suitable embodiments may be utilized and that logical, mechanical, chemical and electrical changes may be made without departing from the spirit or scope of such inventive disclosures. To avoid unnecessary detail, the description omits certain information known to those skilled in the art. The preceding detailed description is, therefore, not intended to be limited to the specific forms set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be reasonably included within the spirit and scope of the appended claims.
This patent application claims priority from co-pending U.S. Provisional Patent Application having Ser. No. 61/189,390 filed Aug. 18, 2008, entitled “Rolan's Clampless Adjustable Polish Rod”, having a common applicant herewith and being incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61189390 | Aug 2008 | US |
