Patent Publication Number: US-7909088-B2

Title: Material sensitive downhole flow control device

Description:
FIELD OF THE INVENTION 
     The field of the invention is downhole tools that can be actuated by a material that responds to the presence of certain well fluids so as to actuate a tool. 
     BACKGROUND OF THE INVENTION 
     Wells that are in production are prone to occasional production of undesirable water or unwanted gasses such as methane, for example. When these situations arise it is necessary to cut the production flow and take production from elsewhere in the wellbore or even to drill a new lateral to get away from the migration of those contaminants into the production string. 
     Typically, the production takes place through screens, with or without a gravel pack in the annulus around the screen. In the event of production of a contaminant, it is advantageous to cut off the production flow and to do it automatically at the initial detection of the presence of such a material. 
     The present invention has many applications and is suited to selectively cut off flow to a screen section where the foreign material is sensed. It can be employed with an Equalizer® Screen sold by Baker Oil Tools or with other tools. In the preferred embodiment a shape memory material that is sensitive to the presence of the undesired contaminant is used to hold in a check an energy source. Once the contaminant is detected the material properties of the shape memory material change and the potential energy is liberated to allow flow to be blocked. Those skilled in the art will appreciate that other applications or the reverse of the preferred operation are also envisioned and that the full scope of the invention is given by the claims that appear below. 
     SUMMARY OF THE INVENTION 
     A screen section has a valve assembly to control flow through it. The valve is open and has a closure spring held compressed by a shape memory material that responds to the presence of a specific well fluid or fluids so that its property changes to allow the spring to deliver the stored potential energy to the valve member to close it when the specific well fluid or fluids are detected. The preferred material is a shape memory polymer that, for example, is sensitive to the presence of water or methane and gets softer to release the potential energy source to operate the downhole tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an assembly showing the use of the invention in a production screen application to selectively cut off flow through it when a selected material is present. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a screen  1  that has a base pipe  3  behind it so that flow through the screen has to go through a spiral path  8  in housing  2  to reach a port  4 . Housing  2  covers port  4  creating an annular space  9  in which is located a sliding sleeve  5  that has spaced apart seals  10  and  11 . In the  FIG. 1  position, the friction force of the seals  10  and  11  holds the sleeve  5  in position for run in and production through the screen  1 . This happens because the sleeve  5  is in pressure balance in annular space  9 . A source of potential energy, such as a spring  7  is preferably embedded or otherwise held compressed by a material  6  which is a part of the actuating component. The preferred material is of the type that changes physical properties or dimension when in the presence of a material that is sought to be excluded from flowing through the screen  1  in significant quantities. A shape memory material that is sensitive to a specific material or materials can be used as material  6 . One of the materials that can trigger a physical property change can be water or methane gas or another fluid. When that material is produced, the phase change in material  6  makes it go soft so that the compressed spring  7  can extend and push the sleeve  5  to overcome the friction of seals  10  and  11  and cover the port  4 . Those skilled in the art will appreciate that optionally a snap ring can jump into a groove in the base pipe  3  to lock the sleeve  5  in the closed position after it is shifted by the stored energy force, in the case of the preferred embodiment, being the spring  7 . 
     Those skilled in the art will appreciate that the spring  7  can be replaced with other potential energy sources or that the material  6  itself can be the potential energy source and the sole actuating component. For example, the material  6  can be bentonite clay that swells in the presence of water and pushes the sleeve  5  to the closed position. Other known shape memory materials that get softer in the presence of the fluid sought to be excluded can be used or yet other materials that are not necessarily shape memory materials but behave in a way that allows a force to be created or released in their presence can also be used. Some materials for this service are certain epoxy resins that deteriorate in the presence of brine at temperature and pressure; or water swellable elastomers that become softer as a % of volumetric swell. 
     The same sleeve  5  can be made sensitive to more than one undesired material by using a plurality of different materials  6  sensitive to different fluids to actuate the same sleeve  5 . Alternatively, the different screen sections can be made to selectively close in response to different undesired fluids whether liquid or gas being produced. 
     An advantage of the present invention is the ability to respond quickly and automatically when the undesired fluid appears and the sheer simplicity of the detection/actuation system which cuts off flow before an unacceptable amount of the contaminant is produced and has to be separated at the surface. 
     While the invention is described in the context of a valve for a screen section, it can be used in many applications downhole to close, or even open valves based on a sensed well condition specific to a target fluid. While on and off application is envisioned, the operation can also contemplate throttling and movement in opposed direction of sleeve  5  based on the level of the undesired material sensed as formation behavior is at times responsive to throttling to make the undesired material migrate to another portion of the well where it will not be produced. Other devices that could also be triggered by the presence of the unwanted fluid include such devices as packers or plugs, for example. While  FIG. 1  shows a closure operation when the undesired material is produced, an override system can be in place to act on sleeve  5  to open it against the bias of spring  7  into a fully open or partially open position. This can be done by making the seals  10  and  11  different sized and getting pressure onto sleeve  5  through port  4  for example. This technique can be used to allow production to restart after the undesired material has migrated to another location and is not any longer being produced. 
     The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: