Abstract:
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.

Description:
RELATED APPLICATIONS 
     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. 
    
    
     BACKGROUND OF THE INVENTION 
     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. 
     SUMMARY OF THE INVENTION 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a pump jack, polish rod, and stuffing box, to which embodiments of the present invention may be utilized. 
         FIG. 2  shows a perspective view of an embodiment of the polish rod alignment device with a stuffing box attached. 
         FIG. 2A  shows a detailed view of the stuffing box attached to the preserver barrel coupling. 
         FIG. 2B  shows a detailed view of the polish rod and preserver barrel extending through a pumping tee fitting. 
         FIG. 3  shows a perspective view of an embodiment of the polish rod alignment device. 
         FIG. 3A  shows a front view of an embodiment of the polish rod alignment device. 
         FIG. 3B  shows a sectional view taken along line A-A of  FIG. 3A . 
         FIG. 3C  shows a close-up view of circled portion of  FIG. 3B . 
         FIG. 4  shows a perspective view of an embodiment of an alignment barrel which may be utilized in embodiments of the polish rod alignment device. 
         FIG. 4A  shows a front view of an embodiment of an alignment barrel. 
         FIG. 4B  shows a sectional view taken along line A-A of  FIG. 4A . 
         FIG. 4C  shows a close up view of the circled portion of  FIG. 4B . Illustrative dimensions are provided for one embodiment of the invention. 
         FIG. 5  shows a perspective view of an embodiment of a nylon sleeve which may be utilized in embodiments of the polish rod alignment device. Illustrative dimensions are provided for one embodiment of the invention. 
         FIG. 5A  shows a front view of an embodiment of the nylon sleeve. 
         FIG. 5B  shows a sectional view taken along line A-A of  FIG. 5A . Illustrative dimensions are provided for one embodiment of the invention. 
         FIG. 6  is a perspective view of an embodiment of a coupling, i.e., centralizer, which may be utilized in embodiments of the polish rod alignment device. 
         FIG. 6A  shows a front view of an embodiment of a centralizer. 
         FIG. 6B  shows a sectional view taken along line A-B of  FIG. 6A . 
         FIG. 7  shows an exploded and sectional view of an alternative embodiment of the polish rod alignment and stabilization device 
         FIG. 8  shows a perspective view of a centralizer which may be used with the alternative embodiment. 
         FIG. 9  shows a sectioned view of the centralizer of depicted in  FIG. 8 . 
         FIG. 10  shows a top view of the centralizer depicted in  FIG. 8 . 
         FIG. 11  shows a bottom view of the centralizer depicted in  FIG. 8 . 
         FIG. 12  shows a perspective view of a nylon sleeve which may be used with the alternative embodiment of the invention. 
         FIG. 13  shows a top perspective view of the nylon sleeve depicted in  FIG. 12 . 
         FIG. 14  shows a bottom perspective view of the nylon sleeve depicted in  FIG. 12 . 
         FIG. 15  shows a perspective view of a barrel adapter which may be used with the alternative embodiment of the invention. 
         FIG. 16  shows a sectioned view of the barrel adapter depicted in  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring now to the figures,  FIG. 1  shows a known pumping unit  10  which is utilized to impart a reciprocating motion to a rod string  16 . The rod string terminates at the surface with a polish rod  12 . As shown in greater detail in  FIGS. 2, 2A and 2B , polish rod  12  reciprocates or rotates within stuffing box  14  which contains internal seal packing elements  26  for maintaining a pressure seal around the polish rod  12 . Referring again to  FIG. 1 , rod string  16  reciprocates within a tubing string  18 . A subsurface pump  20  is actuated by the reciprocal motion of the rod string  16  resulting in fluid flow from the reservoir up through the tubing string  18  and out production line  22  which is typically connected to an outlet of a pumping tee  24 . 
     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 . 
       FIG. 1  schematically depicts one location in which the alignment device  100  may be mounted, where the centralizer  130  is depicted connected to the stuffing box  14 . It is to be appreciated that most of the disclosed apparatus is not shown in  FIG. 1 , because, for this particular embodiment of the alignment device  100 , with the exception of the centralizer  130 , most of the device is contained within the pumping tee  24  and the top joint of the tubing string  18 , and/or any pup joints between the pumping tee and the top joint. Embodiments of the present invention thus provide a guidance mechanism for the polish rod  12  which is almost entirely contained within the upper portion of the tubing string  18 . 
     An embodiment of the alignment device  100  is generally depicted in  FIGS. 2, 2A and 2B . In general, the alignment device  100  has an alignment barrel  110 , an alignment sleeve  120 , and a centralizer  130  to which the stuffing box  14  is attached. As shown in the Figures, the alignment device  100  may be configured with the centralizer  130  mounted at the top of the alignment barrel  110 , with the alignment sleeve  120  disposed within the centralizer  130 . For purposes of this disclosure, the terms “top,” “bottom,” “upper,” “lower,” “above,” and “beneath” are made with reference to the ground surface, with items referred as top, upper, and above located at a higher relative position with respect to the ground surface than items referred to as bottom, lower, and beneath. For the embodiment of the alignment device  100  shown in  FIGS. 2 and 2A , a pin or threaded end on the lower end of stuffing box  14  makes up into internal threads  132  in centralizer  130 . 
     As shown in greater detail in  FIGS. 2 and 2B , in this embodiment of the invention, the alignment barrel  110  is suspended from centralizer  130  such as by making up external threads on alignment barrel up into internal threads in centralizer  130 , or by utilizing a hanger assembly on alignment barrel  110  which lands within a profile in centralizer  130 . Centralizer  130  is attached to pumping tee  24  with the lower threads  134  of the centralizer  130  typically making up into internal threads contained within the production tee  24 . The packing material  26  of the stuffing box  14  will typically be contained within a portion of the stuffing box  14  which is above the alignment sleeve  120 . With this configuration, the polish rod  12  is isolated from the internal pressure of the tubing string  18  by the packing contained  26  within the stuffing box  14 . In this embodiment of the alignment device  100 , alignment sleeve  120 , as shown in  FIG. 2A , is vertically adjacent to the packing material  26 . Alignment sleeve  120  centralizes and guides the polish rod  12  as it is reciprocated up and down inside the packing material  26 . 
     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. 
       FIGS. 7 through 16  show an alternative embodiment of the alignment device  1000 . This embodiment utilizes the same alignment barrel  110  as the embodiment of the alignment device  100  discussed above. Stuffing box  14  will make up into threads  1132  of the centralizer  1130 . In the alternative embodiment of the alignment device  1000 , a barrel adapter  1200  is utilized to attach the alignment barrel  110  to the centralizer  1130 , where alignment sleeve  1120  is captured in the lower portion of centralizer  1130  by the engagement of threads  1210  of the barrel adapter  1200  to internal threads  1140  of the centralizer. Centralizer  1130  further comprises external threads  1134  at the bottom which make up into internal threads of the pumping tee  24  as before. Centralizer  1130  may further comprise a relief port  1150 . 
       FIGS. 12 through 14  depict an embodiment of an alignment sleeve  1120  which might be utilized with the alternative embodiment of the alignment device  1000 . The upper surface  1150  of alignment sleeve  1120  may be tapered to seal against an internal profile within the centralizer  1130 . The lower surface  1160  may seal against a matching surface  1220  in barrel adapter  1200 . 
       FIGS. 15 through 16  depict an embodiment of a barrel adapter  1200  which may be utilized to attach alignment barrel  110  to centralizer  1130  in an embodiment of the alignment device  1000 , such that alignment barrel  110  depends from centralizer  1130 , capturing alignment sleeve  1120  between the centralizer and the barrel adapter. Barrel adapter  1200  comprises external threads  1210  which make up into threads  1140  of the centralizer. Barrel adapter  1200  may further comprise threads  1230  which make up to threads  114  of alignment barrel  110 . 
     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.