Polish rod alignment device/stuffing box packing preserver |
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申请号 | US14596158 | 申请日 | 2015-01-13 | 公开(公告)号 | US09784055B1 | 公开(公告)日 | 2017-10-10 |
申请人 | Black Gold Pump and Supply, Inc.; | 发明人 | Michael Bair; Scott Sakakura; | ||||
摘要 | A polish rod alignment and stabilization device preserves stuffing box packing and protects the polish rod of an oil well sucker rod string by guiding and aligning the polish rod as it reciprocates within the stuffing box thereby reducing lateral motion of the polish rod reciprocates up and down. Embodiments of the invention may also wipe the polish rod of debris as it reciprocates within the device. The alignment device utilizes a rod centralizer to which a stuffing box is made up. The centralizer has a second end to which an alignment barrel depends, either by direct connection or by utilization of a barrel adapter. The alignment barrel is disposed within the uppermost portion of the tubing string of the well. | ||||||
权利要求 | What is claimed is: |
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说明书全文 | U.S. Application No. 61/926,832 for this invention was filed on Jan. 13, 2014, for which application these inventors claim domestic priority, and which application is incorporated in its entirety. The present invention generally relates to artificial lift systems which are utilized for production of fluids from subsurface reservoirs, including oil, water, and liquid phase hydrocarbons. More particularly, the present invention is utilized with artificial lift systems where a subsurface pump is actuated by a plurality of rods connected end-to-end, herein collectively referred to as a “rod string.” The rod string is set within a plurality of tubing joints likewise connected end-to-end, wherein the tubing joints are collectively referred to as a “tubing string.” Actuation of the subsurface pump lifts the fluid upwardly from the subsurface pump to the surface, where the fluids flow in the annular space between the rod string and the inside diameter of the tubing string as the fluid flows upwardly. The typical subsurface pump operated by a rod string is a positive displacement pump operated by reciprocation of the rod string. This type of pump has a plunger connected to the rod string, where the plunger reciprocates within a polished barrel located at the bottom of the tubing string such that liquids are drawn into the pump barrel and lifted upwardly through the tubing string. The reciprocating motion of the rod string is typically imparted by a pump jack. For this system, the uppermost rod in the rod string is a polish rod. The polish rod reciprocates in and out of a stuffing box. The stuffing box is a close-fit assembly which cleans the polished rod, prevents debris from entering or exiting the well, and further prevents fluid from leaking from the well during operation. The stuffing box is typically mounted above a T-fitting or pumping tee cross at the top of the tubing. The stuffing box provides a dynamic seal along the length of the polish rod. The stuffing box typically has a central passage through which the polish rod moves, while stuffing or packing material is compressed against the sides of the polish rod to create a fluid seal. The packing materials are typically elastomers and other materials which are softer than the polish rod material. The movement of the polish rod within the packing material generates friction, and thus heat, which breaks down and degrades the packing materials contained within the stuffing box. This breakdown and degradation reduces the integrity of the seal formed between the packing material and the polish rod. The presence of solids in the produced fluid, such as sand, can accelerate this degrading of the packing material and can adversely impact the life of the polish rod, potentially resulting in a polish rod failure. The loss of the integrity of the seal between the polish rod and the packing material will result in the escape of fluids from the well which can result in environmental damage and the loss of valuable resources, and can result in significant clean-up expense and potential fines and penalties. Accelerated packing replacement also requires the expenditure of man-hours to replace the packing which might otherwise be avoided. Solutions to the above problem typically focus on the packing material, such as utilizing a different type of packing material or attempting to reduce the friction between the polish rod and the packing material, and therefore reduce the thermal degradation. Embodiments of the presently disclosed invention provides a solution to the problems identified above by addressing the problem by guiding and aligning the polish rod as it reciprocates within the stuffing box thereby reducing lateral motion of the polish rod. Embodiments of the invention may also wipe the polish rod of debris as it reciprocates within the device. In one embodiment of the invention, a coupling member, hereinafter referred to as the “centralizer” has threads on one end into which the threads of a pin end of the stuffing box are made up. The centralizer has a second end to which an alignment barrel depends, either by direct connection or by utilization of a barrel adapter. In a first embodiment of the invention, as the stuffing box is attached to the centralizer, the stuffing box is slid over a nylon sleeve through which the polish rod is inserted. In a second embodiment of the invention, the stuffing box is made up to the centralizer and the nylon sleeve is captured on the bottom side of the centralizer by the barrel adapter. In both embodiments, an alignment barrel depends from the centralizer, either by direct connection to the centralizer or by utilization of the barrel adapter, which makes up into the bottom of the centralizer. The polish rod reciprocates within the alignment barrel and the nylon sleeve. The alignment barrel may comprise slots to allow for the passage of oil, scale and solids which may accumulate on the polish rod. The alignment barrel has an inside diameter which is smaller than the outside diameter of the coupling which attaches the polish rod to the top rod of the rod string, such that should the alignment barrel become detached from the centralizer, the alignment barrel can fall through the tubing no further than down to the connection between the polish rod and the top rod of the rod string. Referring now to the figures, Stuffing box 14 maintains a seal between the polish rod 12 and the tubing string 18. An embodiment of an apparatus for maintaining the alignment of the polish rod with respect to the stuffing box 14, referred to hereinafter as the alignment device 100, forms an extended chamber for travel of the polish rod 12. An embodiment of the alignment device 100 is generally depicted in As shown in greater detail in For illustration purposes, in one embodiment of the invention, alignment sleeve 120 may have a length of approximately 3 inches and an inside diameter of approximately 1.5 inches, although the outside diameter of the alignment sleeve 120 is dependent upon the bottom inside diameter of the stuffing box or blow-out preventer into which upper edge 121 seats. The outside diameter of the alignment sleeve 120 must also fit into the top of the centralizer and mate to the designated face. For this reason, the alignment sleeve 120 may have a chamfered bottom edge 123 which seats within a corresponding chamfered portion of the centralizer 130, such that the faces are aligned and mated within the centralizer. Alignment sleeve 120 may be fabricated from nylon. Alignment barrel 110, which may be fabricated from carbon steel or appropriate corrosion resistant materials and, in one embodiment, have an inside diameter of approximately 1.6 inches. The length L of alignment barrel 110 will be somewhat dependent upon the stroke length of the downhole pump 20. However, alignment barrel 110 will generally have a length greater than one foot, and may be several feet in length or longer. Thus, support and guidance for the polish rod 12 is provided for a significant distance adjacent to the stuffing box 14. In most embodiments of the invention the outside diameter of the coupling which connects the top rod of rod string 16 to the bottom of polish rod 12 will be larger than the inside diameter of the alignment barrel 110, so the pump must be spaced such that the coupling is not pulled up into the bottom of the alignment barrel. This feature prevents the alignment barrel 110 from falling to the bottom of the tubing string 18 should the alignment barrel become detached from the centralizer 130, but rather the alignment barrel will be stopped by the coupling which connects the top rod of rod string 16 to the bottom of polish rod 12, such that the alignment barrel is relatively easy to recover in such situations. As shown in the figures, alignment barrel 110 has slots 112 penetrating through its side walls which allow liquids, as well as any scale, solids, etc., which are produced up through the tubing to exit the alignment barrel 110. By way of example only, slots 112 may have a width of 0.625 inches and a length of approximately 3 inches and may be identical on either side of the barrel. This embodiment of the alignment device 1000 allows manufacturing of a single centralizer body 1130 which may be utilized with three sizes of barrel adapter 1200, such that embodiments of the device may accommodate three sizes of polish rod, specifically 1.25″, 1.50″, and 1.75″. While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. Thus the scope of the invention should not be limited according to these factors, but according to the following appended claims. |