Abstract:
A pressure control system for a wet connect/disconnect hydraulic control line connector includes a reservoir and a piston in said reservoir. The reservoir contains hydraulic fluid or equivalent and the piston is biased by hydrostatic pressure or an atmospheric chamber and hydrostatic pressure. Pressure in the hydraulic line being controlled by the system is controllable based upon the existence or lack of an atmospheric chamber and its placement. The method for controlling pressure in a hydraulic control line wet connector includes running the control system and biasing the piston to control pressure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of an earlier filing date from U.S. Provisional Application Serial No. 60/342,722 filed Dec. 19, 2001, the entire disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND  
         [0002]    Control of tools in the downhole environment and transmission of information between different points of the same has been both a point of great success and a conundrum for many years. Methods for control of the tools and the transmission of information continue to progress and with that progression comes new problems and issues associated with such control and communication. Methods and apparatus capable of enhancing the quality of such communications have historically included hydraulic line. More recently, electric conductors have been employed and most recently the industry has worked to create optic fiber assemblies capable of withstanding the harsh downhole environment in order to take advantage of the speed and accuracy of communications with optic fibers as well as the opportunity to use the fiber as a sensory device. There has been great success achieved in the area. Moreover, evermore tools and sensors are being used in the downhole arena. These require control and communication and employ all of hydraulic control lines, electronic conductors and optic fibers.  
           [0003]    As the technology becomes more ubiquitous, the ability to manufacture and install such communication pathways competitively becomes increasingly important.  
           [0004]    While it has been demonstrated that the communications conduit noted can be successfully installed in a wellbore during completion thereof, there has been little done with respect to “wet” connections of lengths of these conduits.  
         SUMMARY  
         [0005]    A pressure control system for a wet connect/disconnect hydraulic control line connector includes a reservoir and a piston in said reservoir. The reservoir contains hydraulic fluid or equivalent and the piston is biased by hydrostatic pressure or an atmospheric chamber (or selected pressure chamber) and hydrostatic pressure. Pressure in the hydraulic line being controlled by the system is controllable based upon the existence or lack of an atmospheric chamber and its placement. The method for controlling pressure in a hydraulic control line wet connector includes running the control system and biasing the piston to control pressure. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    Referring now to the drawings wherein like elements are numbered alike in the several Figures:  
         [0007]    [0007]FIG. 1 is a cross-sectional view of a first embodiment of the pressure compensation system;  
         [0008]    [0008]FIG. 2 is a cross-sectional view of a second embodiment of the pressure compensation system;  
         [0009]    [0009]FIG. 3 is a cross-sectional view of a third embodiment of the pressure compensation system;  
         [0010]    [0010]FIG. 4 is a cross-sectional view of a fourth embodiment of the pressure compensation system;  
         [0011]    [0011]FIG. 5 is a cross-sectional view of a fifth embodiment of the pressure compensation system; and  
         [0012]    [0012]FIGS. 6 and 7 are illustrative of an embodiment with a relief valve therein. 
     
    
     DETAILED DESCRIPTION  
       [0013]    Referring to FIG. 1, a balanced piston embodiment is illustrated. The system, indicated generally at  10 , comprises a female connector discussed herein as a mating profile  12  (available commercially as a “wear bushing connector” from Baker Oil Tools, Houston, Tex.) in fluid communication with a drill hole  14  (any type of conduit is acceptable providing it is capable of conveying fluid and pressure as disclosed herein), which is in fluid communication with one end  16  of a hydraulic fluid reservoir  18 . A piston  20  is positioned within reservoir  18  and separates hydraulic fluid  22  in reservoir  18  from wellbore fluid  24  which may move into and out of reservoir  18  through port  26  depending upon a pressure gradient between the hydraulic fluid and wellbore fluid. When wellbore fluid pressure is increased, for example due to an increase in the depth at which the tool is positioned, region  28  of reservoir  18  expands and region  30  of reservoir  18  is made smaller by movement of piston  20 . Fluid  22  within region  30  is urged to move into hole  14  to increase the pressure thereof to match hydrostatic pressure. By so configuring the system, the pressure of the hole  14  (and any conduit in fluid communication therewith, e.g. line  33 ) including all connections thereof can be maintained at a pressure substantially equaling ambient hydrostatic wellbore pressure at any given depth effectively reducing stress upon such components and lengthening the anticipated working lives thereof. Piston  20  prevents transfer of wellbore fluids to region  30  of reservoir  18  thus preventing infiltration of wellbore fluids into the hydraulic conduit  14 , 33  which would otherwise be detrimental thereto.  
         [0014]    Furthermore, hydraulic fluid  22 , which of course is the same fluid through hole  14 , connector  32  and hydraulic line  33  extending to a downhole location, is at the same pressure as ambient wellbore pressure. Thus it is not likely wellbore fluid will enter the line  33  through connector  32  when system  10  is removed.  
         [0015]    In a second embodiment, referring to FIG. 2, reservoir  18 , piston  20  and port  26  are identical to the foregoing embodiment. Distinct however, is an augmenting piston  34  that defines an atmospheric chamber  36 . It is noted that although several embodiments herein refer to an “atmospheric” chamber, a selected pressure chamber having any particular pressure therein can be substituted with commensurate changes in the cumulative effect of the system. While wellbore fluid  24  acts upon piston  34  similarly as it did upon piston  20  in the foregoing embodiment, in this embodiment piston  20  is acted upon by both wellbore fluid  24  and piston  34 . Piston  34  has increased impetus to move from atmospheric chamber  36 , which when in an environment having a pressure greater than atmospheric functions like a vacuum and draws piston seal flange  38  toward mandrel seal flange  40 . Since both forces act in concert the pressure created in reservoir  18  is in excess of ambient wellbore (hydrostatic) pressure. This is desirable in some applications because upon removing system  10  from connector  32 , the excess pressure in hydraulic pathway will cause an expression of fluid from connector  32 . The fluid tends to clear any debris from the end of connector  32  and additionally creates a bubble of clean hydraulic fluid around the same, which assists in keeping connector  32  clear of debris.  
         [0016]    Referring to FIG. 3, another embodiment is illustrated. This embodiment is intended to limit the depth up to which the pressure inside reservoir  18  and hydraulic conduit  14 ,  33  may be increased by ambient wellbore pressure. It will be appreciated that this figure is identical to FIG. 1 except for the addition of stop collar  42  placed within reservoir  18 . With stop collar  42  in place, it will be understood that piston  20  can only be urged so far to the right (in the figure) by ambient wellbore pressure entering region  28  of reservoir  18  through port  26 . In this embodiment pressure in reservoir  18  and hole  14  (and therefore line  33 ) will be maintained at ambient wellbore pressure until the pressure of the wellbore (usually due to depth) increases to a degree beyond that which would have moved piston  20  into contact with stop collar  42 . With increasing pressure beyond the pressure at which piston  20  will hard stop against stop collar  42 , the pressure in region  30  of reservoir  18  and in hole  14  will begin to be less than ambient wellbore pressure. This is useful if a reduced pressure relative to ambient pressure is desirable in hydraulic conduit  14 ,  33  for a particular application. One such application where the discussed result is useful is where the wellbore fluid is to be changed to a lighter fluid prior to removing the cover (wear bushing: commercially available from Baker Oil Tools, Houston, Tex.) from connector  32 .  
         [0017]    In yet another embodiment, referring to FIG. 4, an active approach is taken to maintain the pressure in reservoir  18  and hole  14  at a selected amount below ambient pressure. This embodiment employs a compensation piston  50  having a piston seal flange  52  located more toward hole  14  than mandrel seal flange  54 . Between flanges  52  and  54  is defined an atmospheric chamber  56 . Upon ingress of wellbore fluid  24  through port  26 , piston  20  is urged toward hole  14 , which necessarily causes atmospheric chamber  56  to expand in volume without a complementary increase in pressure. In such situations it will be appreciated that atmospheric chamber  52  will have less than atmospheric pressure therein commensurate with the amount of volumetric increase of the chamber. Therefore, the more the hydrostatic pressure based force expands the chamber in volume the more there is a complementary decrease in pressure. Stated differently, the more pressure based force is exerted against piston  20  by the wellbore fluid  24 , the more counterforce is exerted by compensation piston  50  due to the increasing volume (and consequently decreasing pressure) in “atmospheric” chamber  56 . The atmospheric chamber  56  is energized by the reservoir pressure. Because of the atmospheric chamber  56  working against the wellbore pressure, the pressure in reservoir  18  and hydraulic conduit  14 ,  33  will remain below hydrostatic (ambient) wellbore pressure by a calculable amount commensurate with depth of the system.  
         [0018]    In a final embodiment, referring to FIG. 5, the embodiment of FIG. 4 is adjusted to provide for a more pronounced wellbore pressure-to-reservoir pressure differential. The distinction is achieved by removing the atmospheric chamber  60  to the wellbore side of reservoir  18 , or region  28 . In this embodiment, piston  20  from prior embodiments is omitted and compensation piston  62  includes a seal piston  64  on the reservoir contact end thereof. Atmospheric chamber  60  is defined between piston  64  and mandrel seal flange  68 . Compensation piston  62  is open on its other end  66  to wellbore fluid  24  and the pressure thereof through port  26 . As implied this arrangement results in a pressure in reservoir  18  and hydraulic conduit  14 ,  33  lower than hydrostatic (ambient) pressure  
         [0019]    Referring now to FIGS. 6 and 7 one will appreciate the incorporation of a relief valve  70 . A relief valve may be incorporated in each of the foregoing embodiments as desired to accommodate expansion of the hydraulic fluid due to elevated downhole temperatures. Valve  70  is an automatic pressure relief valve configured to relieve pressure at a selected valve. Such valves are commercially available from the Lee Company, a well known commercial supplier.  
         [0020]    Relief valve  70  extends from a recess  72  in an outside dimension of the tool to hole  14  in the body of the tool. This provides a fluid pathway for escape of overpressurized hydraulic fluid in hole  14  such that other components of the system such a seals are not damaged by overpressurization.  
         [0021]    While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.