Abstract:
A wellhead for a hydrocarbon-producing wellbore includes a wellhead body having an inner cavity, and a production fluid conduit. The production fluid conduit and the wellbore define a production fluid flow path. A stuffing box is positioned within the inner cavity. A leak containment structure within the inner cavity captures any fluid exiting the stuffing box. A fluid pump pumps fluids from the leak containment structure to the production fluid flow path.

Description:
FIELD 
     This relates to a wellhead for a hydrocarbon-producing wellbore, such as a wellhead with a leak containment structure that retains wellbore fluids that may leak from the wellhead. 
     BACKGROUND 
     Wells are drilled as a means to target oil and gas bearing formations at a particular depth. Where formations lack sufficient pressure to push fluids to surface, some form of “Artificial Lift” is employed to lift reservoir fluids from the wellbore. A common form of artificial lift consists of a pump at surface (such as a Pumpjack) that reciprocates a positive displacement pump downhole. The surface equipment is attached to the downhole pump via a string of sucker rods with a polished rod at surface. Reservoir fluids brought to surface are redirected at a surface wellhead and exit down a flowline. 
     To prevent wellbore fluids from exiting at the wellhead, a stuffing box is used to seal around the reciprocating polished rod. Stuffing boxes contain packing to provide a seal, but will leak over time allowing wellbore fluids to exit at the wellhead and contaminate the surrounding ground. Several catch basins have been designed as a means to contain fluids leaked at the wellbore and to store these fluids for future disposal. Some examples include United States Patent Publication No. 2004/0182567 (Matthews) entitled “Wellhead leak containment and blowout deflection apparatus,” U.S. Pat. No. 5,484,024 (Ladd) entitled “Oilwell spill containment,” and U.S. Pat. No. 4,949,784 (Evans) entitled “Wellhead leak containment”. 
     SUMMARY 
     There is provided a wellhead for a hydrocarbon-producing wellbore, comprising a wellhead body and a production fluid conduit. The wellhead body mounts on a wellbore and has an inner cavity. The production fluid conduit and the wellbore defining a production fluid flow path. A stuffing box is positioned within the inner cavity. There is a leak containment structure within the inner cavity to capture any fluid exiting the stuffing box. A fluid pump pumps fluids from the leak containment structure to the production fluid flow path. 
     According to another aspect, the fluid pump is connected to the production fluid conduit. The fluid pump preferably comprises a check valve for preventing fluid flow from the production fluid conduit to the leak containment structure. 
     According to another aspect, there may be an access door that provides access to the inner cavity. 
     According to another aspect, the fluid pump may be a metering pump, such as an electric metering pump or a diaphragm metering pump. The pump may be actuated by casing gas pressure from the wellbore. 
     According to another aspect, the leak containment structure may be integrally formed with the wellhead body. 
     According to another aspect, the fluid pump may pump the fluid into an internal passageway portion of the production fluid conduit in the wellhead, or into a flow line portion of the production fluid conduit that is external to the wellhead. 
    
    
     
       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 front elevation view, partially in section, of a wellhead with an integral catch basin. 
         FIG. 2  is a side elevation view, partially in section, of the wellhead with an integral catch basin shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A wellhead with integral catch basin, generally identified by reference numeral  10 , will now be described with reference to  FIGS. 1 through 2 . 
     Structure and Relationship of Parts: 
     Referring to  FIG. 1 , wellhead  10  has an internal stuffing box  12 , internally contains any leaked fluid in an integrally formed catch basin  14 , and overcomes flowline pressure via a metering pump  16  to dispose of fluids in catch basin  14 . The fluids may be returned to the production fluid flow path, which may be considered to include the wellbore and the production flow line  20 . Referring to  FIG. 2 , this system is not an addition to a wellhead, but rather is part of the wellhead itself. Wellhead  10  is shown as being connected to a casing bowl  18  by bolts  21 , but could be mounted to the wellbore by other components as well. 
     Referring to  FIG. 1 , wellhead  10  has a wellhead body  22  with an inner cavity  24 . Wellhead  10  has a production fluid conduit in the form of a flow line  20  and an internal passageway  26  through wellhead  10 . Flow line  20  is in communication with the wellbore (not shown). A stuffing box  12  is positioned within inner cavity  24 . A leak containment structure, depicted as a catch basin  14 , is positioned within inner cavity  24  to capture any fluid that may leak through and exit stuffing box  12 . 
     As shown in  FIG. 1 , the leak containment structure  14  is connected to the production fluid flow path  20  by an internal flow conduit within the wellhead body  22 . This allows fluid captured by the leak containment structure  14  to be routed internally within the wellhead body  22  to the production fluid flow path  20 . A fluid pump, such as metering pump  16 , is used to pump fluids from the leak containment structure  14  to the production fluid flow path  20 . Fluid pump  16  is shown to pump fluids through an internal passageway  26  to a point immediately upstream of flow line  23 . It will be understood that passageway  26  need not be internal, and may be connected to various points of the production fluid flow path, such as an external flow line  23 . Fluid pump  16  preferably has a check valve  30  to prevent fluid flow from the production fluid conduit  26  to leak containment structure  14 . An access door  32  is preferably provided to allow access to the inner cavity  24 . A test flow line  40  may also be provided on wellhead  10 . 
     The metering pump  16  may be an electric pump, a diaphragm pump or any other type of pump suitable for the conditions. The metering pump  16  may also be pneumatically actuated by casing gas from the well. 
     A blowout preventer  34  is also preferably integrated into wellhead  10  to contain the wellbore pressure around polished rod  36 . The most likely place for leakage from stuffing box  12  is where polished rod  36  enters and exits. Packing  38  may be used to surround the areas where polished rod  36  enters and exits parts of wellhead  10 . The ultimate design of wellhead  10  will depend on the preferences of the user, and may include more or fewer features described herein. Furthermore, as will be apparent, some elements may be attached to wellhead  10  rather than integrally formed, such as blowout preventer  34 . 
     Operation: 
     Referring to  FIG. 1 , Wellhead  10  is connected to wellhead base  18  by bolts  21 . Wellhead  10  has a wellhead body  22  that has an internal cavity  24  in which an internal stuffing box  12  and an integral catch basin  14  are positioned. Polished rod  36  travels through internal cavity  24 , stuffing box  12 , integral catch basin  14  and blow out preventer  34  before entering the wellbore. As polished rod  36  is reciprocated to pump fluids through wellhead  10 , fluids may leak through stuffing box  12 . When leakage occurs, the fluids are captured by catch basin  14  and prevented from exiting wellhead body  22  and contaminating the area surrounding the wellhead. As catch basin  14  begins to fill with fluid, fluid pump  16  pumps fluids from catch basin  14  back into the production fluid flow path, such as immediately upstream of flow line  20  through a passageway  26 . This may occur at predetermined levels, or whenever fluids are detected. A check valve  30  is connected to pump  16  to prevent fluid flow from production fluid conduit  26  to leak into containment structure  14 . An access door  32  is provided on wellhead body  22  to allow access to inner cavity  24  for maintenance of stuffing box  12  and catch basin  14 . 
     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 be 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.