Abstract:
A plug drop tool, including a body defining a chamber, a plug initially housed in the chamber and a member disposed with the body. The member is actuatable for selectively enabling communication between the chamber and an annulus at least partially defined by the body. The plug is movable into the annulus when the communication is enabled.

Description:
BACKGROUND 
       [0001]    So called “plug and perf” operations are well known in the downhole drilling and completions industry, particularly with respect to unconventional resource plays (unconventional gas, shale gas, tight gas and oil, coal bed methane, etc.). In a plug and perf operation, a bottom hole assembly is run, e.g., on wireline, into a borehole that is typically cased and cemented and could include both horizontal and vertical sections. The bottom hole assembly includes an isolation tool, a setting tool, and one or more perforation guns. The setting tool is actuated for packing off a production zone with the isolation tool. The one or more perforation guns are then positioned in the borehole and triggered by a signal sent down the wireline. Typically, ball type plugs are used for the isolation tools, e.g., as they provide fluid communication with lower zones, which enables sufficient fluid flow for redeploying the perforation guns in the event that they do not fire properly. After perforation, the bottom hole assembly (sans isolation tool) is pulled out and a ball or other plug member dropped from surface for engaging a seat of the isolation tool for impeding fluid flow therethrough. While the process works adequately, it requires a significant amount of time and fluid to pump a ball downhole. Bridge plugs are occasionally used instead of ball type frac plugs, but these bridge plugs do not enable the aforementioned redeployment of failed perforation guns. Accordingly, alternatives for reducing the time and resources required in plug and play operations while maintaining the benefits of ball type frac plugs are well received by the industry. 
       SUMMARY 
       [0002]    A plug drop tool including a body defining a chamber, a plug initially housed in the chamber, and a member disposed with the body and actuatable for selectively enabling communication between the chamber and an annulus at least partially defined by the body, the plug movable into the annulus when the communication is enabled. 
         [0003]    A bottom hole assembly including an isolation tool, a setting tool operatively arranged for setting the isolation tool in a downhole structure, the setting tool initially connected to the isolation tool and disconnectable therefrom after setting, and a plug drop tool coupled with the setting tool, the plug drop tool configured to drop a plug, the plug operatively arranged to travel downhole and engage the isolation tool after disconnection from the setting tool for enabling isolation by the isolation tool. 
         [0004]    A method of performing a downhole operation including running a bottom hole assembly into a downhole structure, the bottom hole assembly including a setting tool, an isolation tool, and a plug drop tool, setting the isolation tool in the downhole structure with the setting tool, disconnecting the setting tool from the isolation tool, deploying a plug from the plug drop tool, and engaging the plug with the isolation tool for enabling isolation by the isolation tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0006]      FIG. 1  schematically illustrates a downhole assembly; 
           [0007]      FIG. 2  is a cross-sectional view of a plug drop tool of the assembly of  FIG. 1  in a closed configuration; 
           [0008]      FIG. 3  is a side view of the plug drop tool of  FIG. 2 ; 
           [0009]      FIG. 4  is schematically illustrates the downhole assembly of  FIG. 1  in an actuated configuration; 
           [0010]      FIG. 5  is a cross-sectional view of the plug drop tool in communication with an annulus; and 
           [0011]      FIG. 6  is a side view of the plug drop tool of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0013]    Referring now to  FIG. 1  an embodiment of the current invention is illustrated, namely an assembly  10  run into a downhole structure  12 . The downhole structure, could be, e.g., a borehole that is lined, cased, cemented, etc. The assembly  10  is, e.g., run downhole by use of a wireline system. In the illustrated embodiment the assembly  10  includes an isolation tool  14 , a setting tool  16 , a perforation gun  18 , and a plug drop tool  20 . 
         [0014]    For example, in one embodiment, the assembly  10  is, e.g., a bottom hole assembly for a “plug and perf” operation. In this embodiment, the assembly  10  is positioned downhole and the isolation tool  14  is set in the structure  12  by the setting tool  16  for packing off a production zone  22 . The isolation tool  14  and the setting tool  16  could be any suitable tools known in the art. For example, the isolation tool  14  could be retrievable, drillable, etc., and formed from composites, metals, polymers, etc. In one embodiment the setting tool  16  is an E-4 setting tool commercially available from Baker Hughes, Inc. The setting tool  16  is then uncoupled from the isolation tool  14  and the perforation gun  18  positioned within the structure  12  for perforating the zone  22 , as generally illustrated in  FIG. 4 . Multiple perforation guns could be included in the assembly  10  for forming multiple perforated sections in each production zone. 
         [0015]    After perforation, the uncoupled tools of the assembly  10  are removed (the isolation tool  14  remaining downhole) and a plug  24 , corresponding to a complementarily formed seat in the isolation tool  14 , is dropped downhole for isolating opposite sides of the plug tool  14 , e.g., thereby enabling a pressure up event to fracture the production zone  22  through the perforations formed by the gun(s)  18 . The plug  24  could be a ball or take any other suitable form or shape receivable by the isolation tool  14 . The isolation tool  14  could include any suitable seat, such as the one taught in U.S. Pat. No. 7,600,572 to Slup et al., which Patent is hereby incorporated by reference in its entirety. 
         [0016]    Advantageously, the assembly  10  includes the plug drop tool  20  so that the plug  24  can be dropped before or while the assembly  10  is pulled out so that the plug  24  only has to drop a small number of feet as opposed to plugs in conventional systems that must drop hundreds or thousands of feet from surface. In accordance with the above, the plug drop tool  20  is initially in the condition of  FIGS. 2 and 3  during run-in and perforation and transitions to the condition of  FIGS. 5 and 6  for deployment of the plug  24  after perforation. 
         [0017]    In the initial configuration of the tool  20  as illustrated in  FIGS. 2 and 3 , a valve member  26  is disposed with a window  28  formed in a body  30  of the plug drop tool  20 . The window  28  is in communication with an annulus  32  formed between the assembly  10  and the structure  12 , but, as shown in  FIG. 2 , blocked from communication with a chamber  34  formed in the body  30 . Blockage of the window  28  accordingly blocks communication between the chamber  34  and the annulus  32 . By blocking communication between the chamber  34  and the annulus  32 , the plug  24  disposed within the chamber  34  can be run-in and moved with the tool  20 . A cap  36  is included with the tool  20  for preventing the plug  24  from exiting the chamber  34  during run-in and positioning of the perforation guns  18 . The cap  36  and valve member  26  may both be formed as sleeves or rods having passages therethrough for enabling the flow of fluid through the tool  20 . 
         [0018]    The cap  36  is secured to the valve member  26  via at least one strut  38  for enabling forces exerted on the cap  36  to be transferred to the valve member  26 . For example the tool  20  could include a lead screw, spring or other resilient element, magnetic or hydraulically actuated components, etc., or any other device, mechanism, or system arranged for actuating the valve member  26 . This actuation system could be triggered, e.g., by a signal sent via the wireline on which the assembly  10  is run. At least one release member  40 , e.g., a set screw, can be included for preventing premature actuation of the valve member  26 , e.g., until a predetermined threshold force is applied to the cap  36 . 
         [0019]    It is to be further appreciated that in addition or alternatively to axial movement, the member  26  could be actuated differently, e.g., rotational movement could align the struts  38  with the windows  28  for selectively enabling and disabling communication between the chamber  34  and the annulus  32 . In another embodiment, the windows  28  are opened by forming the valve member  26  from a material that is dissolvable, degradable, consumable, corrodible, disintegrable, or otherwise removable in response to a downhole fluid, e.g., acid, brine, etc. Regardless of the mechanism used, actuation (movement, disintegration, etc.) of the valve member  26  will open the window  28 , thereby enabling communication between the chamber  34  and the annulus  32 . 
         [0020]    When the chamber  34  is in communication with the annulus  32  the plug  24  is able to exit the chamber  34  by passing through the window  28  into the annulus  32 . The plug  24  is operatively sized with respect to the annulus  32 , i.e., having a dimension smaller than that of a radial clearance through the annulus  32 . The radial clearance is generally defined by the radially largest portion of the tools past which the plug  24  must travel in order to engage with the isolation tool  14  (e.g., the drop tool  20 , perforation guns  18 , setting tool  16 , etc.). By being so sized, the plug  24  is able to pass by the drop tool  20 , the perforating gun  18  and setting tool  16  of the assembly  10  in order to engage in a corresponding seat of the isolation tool  14  and cause isolation as noted above. 
         [0021]    While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.