Abstract:
A temperature conditioned stuffing box includes a housing having an outer surface, an inner surface defining a packing-receiving bore, a lower surface for attaching to a wellhead and an upper surface. A flow passage through the housing for passing temperature-conditioned fluid through the housing has an input and an output.

Description:
FIELD 
       [0001]    A stuffing box for a wellhead that is temperature conditioned. 
       BACKGROUND 
       [0002]    A stuffing box is a packing gland chamber used to hold packing material compressed around a moving pump rod to reduce the escape of fluids from a well. Instead, the well fluids are directed to a production line. In cold temperatures, stuffing boxes may begin to leak well fluids, the grease or oil may become more viscous, and the well head may freeze. In warm temperatures, the lubricant is less viscous and therefore more difficult to control, which may result in the packing becoming brittle and fatigue more rapidly. 
       SUMMARY 
       [0003]    There is provided a temperature conditioned stuffing box, comprising a housing having an outer surface, an inner surface defining a packing-receiving bore, a lower surface for attaching to a wellhead and an upper surface. A flow passage through the housing for passes temperature-conditioned fluid through the housing, the flow passage having an input and an output. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
           [0005]      FIG. 1  is a side elevation view in section of a temperature conditioned stuffing box with containment. 
           [0006]      FIG. 2  is a side elevation view in section of a temperature conditioned stuffing box attached to a wellhead. 
           [0007]      FIG. 3  is a side elevation view in section of a temperature conditioned stuffing box without containment. 
           [0008]      FIG. 4  is a top plan view of a temperature conditioned stuffing box showing the containment cavity and vertical passages for the temperature conditioned housing. 
           [0009]      FIG. 5  is a partially transparent bottom plan view showing a passage of the temperature conditioned housing connecting two vertical passages. 
           [0010]      FIG. 6  is a perspective view of a flow path. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    A temperature conditioned stuffing box generally identified by reference numeral  10 , will now be described with reference to  FIG. 1 through 6 . 
         [0012]    Structure and Relationship of Parts: 
         [0013]    In cold temperatures, the stuffing boxes  10  tend to leak well fluids. Referring to  FIG. 2 , it has been found that one of the causes of this leakage is that, as the packing gland  12  in a stuffing box  10  becomes cold, it does not compress around the polish rod  14 . In addition, in cold temperatures, the lubricant, such as grease or oil, may also be come stiff and less effective. Furthermore, most wells in cold weather will freeze at the wellhead  16 , including the stuffing box  10 . By using a temperature conditioned stuffing box  10  as described herein, this effect can be prevented, or at least reduced, resulting in less spillage and torn packing glands  12  in the stuffing box  10 . In warm temperatures, the stuffing boxes  10  also risk leaking as the lubricant becomes more difficult to control, resulting in more brittle packing that fatigues more rapidly. In both situations, a more moderate temperature may reduce the risk of leakage. 
         [0014]      FIG. 2  shows the temperature conditioned stuffing box housing  18  on a typical wellhead  16 , flanged above a flow-tee  22  of the wellhead  16  and the radigan blowout preventer  24 . Below that is the wellhead tubing bonnet  28 . Above the stuffing box  10  is a driver  30  that drives the polish rod  14 . While the driver  30  is shown to be a hydraulic cylinder, it will be understood that the stuffing box  10  may be adapted to be used with polish rods  14  that rotate or that reciprocate, and that the driver  30  may therefore be a drive head that rotates the polish rod  14 , or a pumping jack the reciprocates the rod vertically. 
         [0015]    As the drive head  30  or jack causes fluids to be pumped from the well, the fluids come up the well into the wellhead  16 , and exit through the flow-tee  22 . The packing glands  12  of the stuffing box  10  seal against the polish rod  14  to prevent fluid from flowing up through the stuffing box  10 . The stuffing box  10  is preferably provided with a lantern spring  32  to compress the packing  12  as it wears. A plate  36  is bolted over the spring  32  and the packing gland cavity  38  to enclose the packing. A cavity  38  is located at the top of the stuffing box  10  above the plate  36  that contains the packing  12  and where the polish rod  14  exits the packing glands  12 . The driver  30  or another plate  40  may be bolted on top to form a containment chamber  42  with the cavity  44  to contain any fluids that leak through the packing glands  12 . As the chamber  42  fills with fluid, it may be piped to a holding system  45  through a test cock  46 . 
         [0016]    Referring to  FIG. 1  and  FIG. 3 , the housing  18  of the stuffing box  10  is formed to have a “temperature conditioned housing”, with an input  48  and an output  50  for temperature conditioned fluid to flow through. Examples of heated fluids that are generally available on a well site include heated water, steam, hydraulic oil, engine coolant, etc. Examples of generally available cooling fluids include water, such as pumping water through the passages, etc. It will be understood that any suitable fluid may be used to heat or cool the housing  18 . The temperature-conditioned fluid may be used to maintain the packing gland  12  at a constant temperature or within a preferred temperature range. The housing  18  may be formed by casting, machining, or a combination of methods. Referring to  FIG. 4  and  FIG. 5 , the passages  52  in the housing are preferably made by machining, and connect the various passages  52  to create a flow path that flows around the packing glands  12  (not shown in these figures) in the body. This may be done by having a series of inputs  48  and outputs  50  that connect the passages  52  externally, or preferably, by sealing the holes at the surface of the housing  18  while leaving the adjacent channels  52  connected inside the housing  18 . The channels  52  may be formed vertically as well as horizontally to achieve a higher coverage.  FIG. 5  shows a series of horizontal and vertical passages  52  that pass around the stuffing box  10 . Since the passages  52  are preferably made by machining from the surface, the outside of these passages  52  are filled or plugged to prevent fluid from escaping. An example of a completed flow path between input  48  and output  50  made up of various passages  52  is shown in  FIG. 6 . It will be understood that other flow paths may be made using the principles discussed herein, which may or may not involve 90 degree corners as shown. 
         [0017]    There are different ways of controlling the temperature of the stuffing box  10 . Since the stuffing box  10  is able to operate in a range of temperatures, it is not always necessary to maintain a specific temperature, such as by using a thermostat, although it is possible to do so. Two main ways of controlling the temperature of stuffing box  10  are to control the temperature of the fluid entering housing  18 , and to control the flow rate of the fluid through housing  18 . For example, heated coolant from an engine, or heated hydraulic oil are readily available sources of heated fluid. However, it is generally easier to provide a flow control that restricts the amount of fluid that enters the housing than to control the temperature of the coolant or oil. 
         [0018]    In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. 
         [0019]    The following claims are to understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.