TEMPERATURE CONDITIONED STUFFING BOX WITH FLUID CONTAINMENT

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

A stuffing box for a wellhead that is temperature conditioned.

BACKGROUND

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

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

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:

FIG. 1 is a side elevation view in section of a temperature conditioned stuffing box with containment.

FIG. 2 is a side elevation view in section of a temperature conditioned stuffing box attached to a wellhead.

FIG. 3 is a side elevation view in section of a temperature conditioned stuffing box without containment.

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.

FIG. 5 is a partially transparent bottom plan view showing a passage of the temperature conditioned housing connecting two vertical passages.

FIG. 6 is a perspective view of a flow path.

DETAILED DESCRIPTION

A temperature conditioned stuffing box generally identified by reference numeral 10, will now be described with reference to FIG. 1 through 6.

Structure and Relationship of Parts:

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.

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.

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.

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.

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.

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.

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.

Claims

1. 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; and

a flow passage through the housing for passing temperature-conditioned fluid through the housing, the flow passage having an input and an output.

2. The temperature conditioned stuffing box of claim 1, wherein the housing has a containment chamber positioned toward the upper surface of the housing relative to the packing-receiving bore.

3. The temperature conditioned stuffing box of claim 2, wherein the containment chamber is formed from a cavity in the upper surface, and a driver attached to the upper surface.

4. The temperature conditioned stuffing box of claim 1, wherein the housing is a unitary piece of material, and the flow passage is formed from a series of connected machined passages.