Abstract:
An apparatus for verifying cement arrival at a target location includes a liner. A sensory structure radially outwardly disposed of the liner at a target arrival location of cement from a cementing operation. The sensory structure configured to sense arrival of cement. A seal configuration automatically responsive to the sensed arrival of cement. Also included is a method for addressing micro annulus formation in a downhole cementing operation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of an earlier filing date from U.S. Non Provisional application Ser. No. 12/195,074 filed Aug. 20, 2008, the entire disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    Liner hangers in the hydrocarbon recovery industry are often cemented into a casing string or into an open hole both to keep them in place and to seal annularly around the liner hanger. While this is often effective for its intended purpose, it is known in the industry that cracks may sometimes form in the cement immediately adjacent the liner or liner hanger. These cracks form what is known as a “micro annulus” through which it is possible for gas or other fluid to migrate to a place in the well where such fluid is undesirable, or even to the surface. In general, the cracks are due to cementing procedure or composition that is inappropriate for the conditions where the cement will be installed. This may be due to operator error or to a change in conditions in the well or a lack of knowledge about the conditions in the well. 
         [0003]    Having a micro annulus is undesirable as generally they reduce productivity of the well by contaminating the production stream or creating other problems requiring additional procedures. This causes delay; and delay, it is known, costs money. The art would therefore well receive additional apparatuses and methods that effectively address the foregoing issues. 
       SUMMARY 
       [0004]    An apparatus for verifying cement arrival at a target location includes a liner; a sensory structure radially outwardly disposed of the liner at a target arrival location of cement from a cementing operation, the sensory structure configured to sense arrival of cement; and a seal configuration automatically responsive to the sensed arrival of cement. 
         [0005]    A method for addressing micro annulus formation in a downhole cementing operation includes cementing a liner in a borehole; sensing an arrival of the cement at a target location; automatically deploying a seal into contact with the cement. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0007]      FIG. 1  is an overview of a liner hanger and liner disposed within a borehole and having an actuable annular seal; 
           [0008]      FIG. 2  is the illustration of  FIG. 1  with a slug of cement illustrated between two wiper plugs being pumped downhole; 
           [0009]      FIG. 3  is a view of the same configuration as that in  FIG. 1  but with the cement having been forced into the annulus; and 
           [0010]      FIG. 4  is an enlarged view of a sensory and/or seal arrangement within the circumscribed area  4 - 4  in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIG. 1 , a formation  10  having a casing segment  12  therein is schematically depicted. A liner hanger  14  is disposed within the casing  12  and hangs a liner  16 . In this embodiment the liner  16  is in an open hole but it is to be appreciated that the liner could be in a cased hole without affecting the operation or purpose of the invention. A liner shoe  20  is depicted at a downhole end of the liner  16  and a liner running tool  22  is depicted at an uphole end of the figure. A sensory and/or seal configuration  24  is illustrated disposed about the liner  16 . The sensory and/or seal configuration  24  can function in a number of ways. In one embodiment, the configuration  24  acts as a sensory tool alone to verify arrival of cement  25  (see  FIG. 2 ) at a target location. This embodiment assists the operator of a well in that there is a positive feedback about the position of the cement  25 . This can be important to the operator since, as is known, a volume of cement is calculated from relevant information and then pumped downhole to its target location. Providing that the annulus size and shape are as expected, the calculated volume of cement will be enough to fill the annular space and the operation works well. Where however, there is a condition in the downhole target area that requires a significantly greater amount of cement, as in for example a washout, the calculated volume of cement will be insufficient to compete the cementing operation. In such a situation, feedback to the well operator would be invaluable as it will signify the need for additional cement to complete the operation or at least will alert the operator to the need for a decision as to whether a proper cementing job is needed at that location or if an incomplete job as indicated will suffice for the particular location. 
         [0012]    In one embodiment, a sensor is included that is capable of sensing the presence of cement. This can be done in a number of ways, for example, but not limited to, density measurement, alkalinity measurement, optic measurement, electrical impedance measurement across a pair of electrodes, etc. All of these and others are capable of recognizing the difference between borehole fluids and the cement  26  and therefore will provide a signal that is accurate with respect to the arrival of the cement. The sensor should be positioned proximate a planned end of cement movement. Pumping and arrival of the cement at its destination is schematically illustrated in  FIGS. 2 and 3 . Using the sensor and communicating the information back to the operator allows confirmation that the cementing job filled the cavity it was intended to fill or that it did not. In the event that the cement did not fill the cavity, the operator can take appropriate action as noted above. Communication of the information back to the surface in one embodiment is effected through the use of a wired pipe, such as intellipipe as the running tool  22 . It is also possible to run any other type of communication conduit to the configuration  24  in order to carry a signal between the configuration  24  and a controller  28  whether proximate to or remote from the configuration  24 . 
         [0013]    Referring to  FIGS. 3 and 4 , the capability that configuration  24  brings with respect to sensory information also makes it quite useful with respect to addressing micro annulus cracking problems. This is because the configuration  24  can be used to communicate to the operator of the well that the cement has achieved a position that is appropriate to deploy a seal member  30 . Such a seal member may be set at any time after the cementing operation is complete but ideally will be set while the cement is still not beyond the green state so that the seal itself will form the cement when the seal is deployed. This ensures that a positive pressure holding seal will be created that will deadhead any fluid flowing through a micro annulus that might have been formed or might be formed in the cement. 
         [0014]    In one embodiment, the deployment of the seal  30  is made automatic upon the sensing of cement at the target location. In this embodiment, intervention from the surface is not necessary. In another embodiment, a signal is sent to the surface where a decision on further action can be made. In yet another embodiment, a downhole controller whether remote from or adjacent to the configuration  24  can be programmed to take certain actions under certain inputs from the configuration  24 . 
         [0015]    Referring to  FIG. 4 , one embodiment of the configuration  24  is illustrated in a larger form to illustrate the details thereof. Seal  30  is supported by a downhole support  32  at a downhole end thereof and by an uphole support  34  at an uphole end thereof. The respective supports  32  and  34  may be dedicated supports or may be features of other components of the tool without change in their function. Seal  30  may be constructed of elastomeric material, metallic material, composite material, etc. providing that it has properties enabling it to increase in a radially outward dimension, or otherwise into the cement, upon actuation. In one embodiment, the seal is an inflatable seal whereas in other embodiments the seal could be mechanically actuated through, for example, axial compression. In any case, the seal  30  is not actuated until cement from the cementing operation reaches a sensory structure  36  of the configuration  24 , which while it may be positioned anywhere on the configuration  24 , is particularly beneficially placed downstream of the seal  30  (in the direction of cement travel) to ensure that when the cement is detected, the seal is already covered in the cement. The sensory structure  36  is operably connected to a decision making controller which may be a downhole controller, uphole controller, controller at the surface or an operator. The connection may be wired as indicated at  40  or may be wireless. 
         [0016]    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.