Patent Abstract:
A flow tolerant actuating device includes, a first tubular having a first portion with a first minimum radial dimension, a second tubular surrounding the first tubular that is cyclically movable relative thereto having a second minimum radial dimension, and a protrusion extending from the second tubular having a third minimum radial dimension. The third minimum radial dimension is greater than the first minimum radial dimension and less than the second minimum radial dimension. The protrusion is positioned relative to the first minimum radial dimension in an upstream direction relative to an anticipated fluid flow direction, and the protrusion is configured to reduce downstream forces on the first tubular due to fluid flow.

Full Description:
BACKGROUND 
       [0001]    Tubular actuators are often actuated by pressure built upstream of a plug seated at a member movable within a tubular. Fluid flowing past the seat alone (i.e. without a plug seated thereagainst), can generate forces sufficient to cause premature movement of the movable member. Depending upon specifics of an application such movement can be troublesome. Operators of such systems are therefore desirous of devices and methods to overcome the foregoing drawback. 
       BRIEF DESCRIPTION 
       [0002]    Disclosed herein is a flow tolerant actuating device. The device includes, a first tubular having a first portion with a first minimum radial dimension, a second tubular surrounding the first tubular that is cyclically movable relative thereto having a second minimum radial dimension, and a protrusion extending from the second tubular having a third minimum radial dimension. The third minimum radial dimension is greater than the first minimum radial dimension and less than the second minimum radial dimension. The protrusion is positioned relative to the first minimum radial dimension in an upstream direction relative to an anticipated fluid flow direction, and the protrusion is configured to reduce downstream forces on the first tubular due to fluid flow. 
         [0003]    Further disclosed herein is a method of desensitizing an actuator to fluid flow. The method includes, positioning a first tubular within a second tubular the first tubular having a first minimum radial dimension that is smaller than a second minimum radial dimension of the second tubular, flowing fluid through the first tubular and the second tubular. The method further includes directing the flowing fluid to a smaller radial dimension than the second minimum radial dimension upstream of the first minimum radial dimension. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0005]      FIG. 1  depicts a cross sectional view of a flow tolerant actuating device disclosed herein; and 
           [0006]      FIG. 2  depicts a cross sectional view of an alternate embodiment of a flow tolerant actuating device disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0007]    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. 
         [0008]    Referring to  FIG. 1 , a fluid flow tolerant actuating device disclosed herein is illustrated at  10 . The device  10  includes a first tubular  14  that is surrounded by a second tubular  18 . Movement of the first tubular  14  relative to the second tubular  18  causes the device to cycle. A counter (not shown) counts the number of cycles. After a selected number of cycles has been completed additional movement of the first tubular  14  relative to the second tubular  18  causes actuation of the device  10 . The first tubular  14  has a minimum radial dimension  22  on a portion  26  that is smaller than a minimum radial dimension  30  of the second tubular  18  and a minimum radial dimension  34  of a protrusion  38  that extends from a surface  42  of the second tubular  18 . Viscous drag and pressure drop generated by flowing fluid acting on the minimum radial dimension  22  create a downstream force on the first tubular  14 . If the downstream force due to fluid flow is of sufficient magnitude to overcome an upward bias generated by a biasing member  46 , illustrated herein as a compression spring, then the fluid flow can cause the first tubular  14  to move resulting in cycling of the device  10 . 
         [0009]    The actuating device  10  disclosed herein, however, is configured to prevent cycling in response to fluid flow alone. In fact, the actuating device  10  may be configured to cycle specifically in response only to pressure built against a plug or ball (not shown) that is seated at a defeatable seat  50  on the portion  26 . As such, the protrusion  38  disclosed herein is configured to reduce downstream forces on the first tubular  14  due to fluid flow, thereby avoiding undesirable cycling due to fluid flow alone. In essence the device  10  desensitizes the actuating device  10  to the cycling effects of fluid flow. Avoidance of such undesirable cycling can be financially beneficial to operators. In a downhole hydrocarbon recovery system, for example, employing a counter designed to allow several plugs to pass a defeatable seat before preventing passage of a plug, erroneous cycling due to fluid flow can prevent passage of a plug earlier than anticipated. Such premature pluggage can result in a need to run an intervention to remove the non-passing plug, thereby delaying completion and production from the well. 
         [0010]    The protrusion  38  attached to the second tubular  18  disclosed herein is key to preventing undesirable cycling of the device  10 . This is due to the fact that a magnitude of a pressure drop in response to flowing fluid (and thus longitudinal force on the tubulars  14 ,  18  resulting therefrom) is determined, at least in part, by changes in radial dimensions that the flow encounters. As such, by making the minimum radial dimension  34  closer in size to the minimum radial dimension  22  than to the minimum radial dimension  30  a majority of the longitudinal force generated can be experienced by the protrusion  38  rather than by the first tubular  14 . And, by attaching the protrusion  38  to the second tubular  18  the majority of the force is carried by the second tubular  18 . An additional benefit of setting the dimensions  22 ,  20 ,  34  as discussed is the minimization of unintended cycling that could occur due to tools catching on the minimum radial dimension  22  while running such tools through the tubulars  14  and  18 . It should be noted that making the minimum radial dimension  34  smaller than the minimum radial dimension  22  would also decrease both the fluid forces acting upon the first tubular  14  and chances of a tool catching on the first tubular  14  while running thereby, doing so would make cycling and actuation of the device  10  with a plug or ball impractical since the plug or ball would catch on the minimum radial dimension  34  instead of the minimum radial dimension  22  of the portion  26 , as intended. 
         [0011]    Another feature that can decrease forces on the first tubular  14  due to fluid flow is a tapered surface  54  that extends from the minimum radial dimension  34  to the minimum radial dimension  30  on an upstream side of the minimum radial dimension  34  of the protrusion  38 . The tapered surface  54  may be a frustoconical surface that acts as a ramp to both fluid flowing there past and to tools being run therethrough. 
         [0012]    Referring to  FIG. 2 , an alternate embodiment of a flow tolerant actuating device is illustrated at  110 . The device  110  is similar to that of device  10 , therefore only the differences will be described herein. Also like elements from the two devices  10 ,  110  will be identified with the same reference characters. The primary difference between the two devices  10 ,  110  is the addition of a longitudinal gap  58  between the portion  26  of the first tubular  14  and the protrusion  38  in the device  110 . The gap  58  generates a vortex  62  therewithin in response to fluid flow. The vortex  62  creates a low pressure directly upstream of the portion  26  thereby generating a force on the first tubular  14  in an upstream direction that will oppose any downstream forces and help to minimize unintended cycling of the device  110 . Sizing of the gap  58  can influence the effectiveness of the gap  58 . For example, selecting a longitudinal dimension  66  of the gap  58  that is no more than eight times the minimum radial dimension  34  should maintain a low pressure zone upstream of the first tubular  14 . Additionally, a longitudinal dimension  70  of the surface  54  can influence a maximum size of the longitudinal dimension  66  of the gap  58  that will maintain a low pressure of the vortex  62 . Increases in the longitudinal dimension  70 , for example, can allow for increases in the longitudinal dimension  66  of the gap  58  that will maintain a low pressure of the vortex  62 . 
         [0013]    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.

Technology Classification (CPC): 5