Patent Publication Number: US-8967246-B2

Title: Downhole actuator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the United States National Phase of PCT Patent Application No. NO2009/000393 filed on 18 Nov. 2009, which was published in English on Jun. 3, 2010 under Publication No. WO 2010/062186 A1, which claims priority to Norwegian Patent Application No. 20084926 filed 25 Nov. 2008, both of which are incorporated herein by reference. 
     This invention relates to an actuator. More particularly it concerns an actuator for connection to and displacing of a component in a well tubular, as the tubular comprises a driver and a working organ. 
     During work in a borehole such as in a petroleum well it is often necessary to be able to displace a component positioned in the well. The component may typically be a control for a valve. 
     Control of this type is typically constituted by a concentric sleeve in a well tubular where in the sleeve wall is arranged gripping openings for connecting control equipment, and where the control equipment is arranged to be able to displace the control. Prior art control equipment is adapted to the internal diameter of the control and provided with grippers fitting in the gripper openings. 
     For various well technical reasons restrictions may be arranged upstream of the valve in the well tubular. The restrictions may be formed having a considerably smaller internal diameter than the well tubular. In a well tubular of 118 mm internal diameter there may for example be a restriction having 76 mm internal diameter. The restriction prevents the valve being operated by means of known control equipment, as the access to the valve is prevented by the restriction. 
     The object of the invention is to remedy or reduce at least one of the prior art drawbacks. 
     The object is achieved according to the invention by the features stated in the below description and in the following claims. 
     An actuator according to the invention for connection to and displacing of a component in a well tubular comprising a driver and a working organ, is characterised in that the working organ is provided with an in the radial direction spring loaded gripping device complementary fitting in the component. 
     The actuator is in a per se known way connected to such as a cable, a wireline tractor or a coiled tubing. 
     The spring loaded gripping device has a radial displacement length making passing a restriction possible and also the following connection to and displacing of the component having a considerably larger internal diameter than the restriction. 
     The gripping device may be connected to a leaf spring where the leaf spring is preloaded in the radial direction outward from the well tubular central axis. 
     The gripping device is thus positioned closer to the well tubular central axis in its passive position than in its active position. 
     The gripping device may be held in its passive position by means of a releasing device where the releasing device on release allows that the gripper device is displaced spring-loaded to its active position. On return of the releasing device to its passive position the gripping device is displaced outward from its engagement with the component. 
     A sleeve abutting and being displaceable relative to the leaf spring may constitute the releasing device. By adapting the releasing device internal diameter, the releasing device holds the leaf spring and the gripping device in the passive position when the releasing device encircles the leaf spring. 
     The releasing device may be connected to the driver and the leaf spring may be connected to the working organ. When the driver displaces the working organ relative to the driver the leaf spring is first displaced out of the releasing device whereby the leaf spring displaces the gripping device radially to engagement with the component. A further displacement of the working organ relative to the driver causes the component to be displaced relative to the well tubular. 
     The gripping device rear portion may have an angle relative to the well tubular central axis less than 90 degrees. The actuator may thereby be withdrawn outward through the restriction even if the driver should fail. 
     An actuator in accordance with the invention makes operation of components in a well tubular possible even if the component is positioned further down in the well than a restriction. It is self-evident that it is technically and economically very advantageous to be able to operate the component without first having to remove the restriction. 
    
    
     
       In the following is described an example of a preferred embodiment being illustrated in the accompanying drawings wherein: 
         FIG. 1  shows an actuator in accordance with the invention during displacement in a restriction in a well tubular; 
         FIG. 2  shows the actuator where the actuator gripper device is in engagement with a component; 
         FIG. 3  shows the actuator after the component is displaced; 
         FIG. 4  shows a section of the actuator to a larger scale; 
         FIG. 5  shows a cross-section VI-VI in  FIG. 4 ; and 
         FIG. 6  shows a section of the actuator in an alternative embodiment. 
     
    
    
     In the drawings the reference numeral  1  indicates an actuator connected to a wireline tractor  2  positioned in a well tubular  4 . The well tubular  4  has a central axis  6 . 
     The actuator  1  comprises a driver  8  for example in the form of an electric or hydraulic power unit which in a per se known way is arranged to be able to displace a working organ  10  in a direction along the well tubular  4  central axis  6 . 
     The working organ  10  is in its free end portion provided with a steering guide  12  arranged to be able to steer the actuator  1  during displacing of the well tubular  4 . 
     Four outwardly curved leaf springs  14  are at their first end portions  16  articulateably connected to a to the working organ  10  fixedly connected first attachment  18 , see  FIGS. 3 and 4 . In their opposing second end portions  20  the leaf springs  14  are articulateably connected to a second attachment  22 , which is displaceable on the working organ  10 . 
     The leaf springs  14  are at their mid portion given one each gripping device  24  in the form of a gripping bulb  26  arranged to be able to engage the gripping recesses  30  of a component  28 , see  FIG. 2 . The gripping device  24  is also provided with steering bulb  32  arranged to be able to prevent that the gripping device  24  unintentionally engages during displacement in the well tubular  4 . 
     The steering bulb  12  must be placed in a steering recess  34  in the component  28  for the gripping bulb to engage the gripping recesses  30 . 
     The rear portion  36  of the gripping device  24  has an angle  38  with the central axis  6  being less than 90 degrees and preferably less than 45 degrees. 
     A releasing device  40  in the form of a sleeve encircles the working organ  10 . The releasing device  40  is connected to the driver  8 . When the leaf springs  14  are pulled into the releasing device  40 , see  FIG. 1 , the gripping devices  24  are positioned in their passive position near the central axis  6 . When the leaf springs  14  are displaced at least partly out of the releasing device  40 , the gripping devices  24  are positioned in their active position, see  FIGS. 2 and 3 . 
     In  FIG. 1  the actuator is being displaced through a restriction  42  in the well tubular  4 . The leaf springs  14  are positioned pushed into the releasing device  40 . 
     In  FIG. 2  the leaf springs  14  are displaced out of the releasing device  40  by means of the working organ  10 . The leaf springs  14  have displaced the gripping devices  24  into engagement with the component  28 . 
     In  FIG. 3  the working organ  10  has displaced the gripping devices  24  and thereby the component  28  inward into the well tubular  4 . 
     By pulling the leaf springs  14  into the releasing device  40  the gripping devices  24  are deactivated whereafter the actuator  1  may be displaced back through the restriction  42 . 
     Should the actuator  1  driver  8  fail, the actuator may still be pulled out through the restriction  42 . If the actuator  1  is pulled out through the restriction  42  without the gripping devices  24  being brought back to their passive position, then the gripping devices  24  will be resiliently displaced out from their engagement with the component  28 , whereafter the leaf springs  14  abut the restriction  42 . This causes the gripping devices  24  to be displaced in a direction toward the central axis  6  of the well tubular  4 . Due to its shape the gripping device  24  will be displaced further in the same direction when it abuts the restriction  42 . 
     In an alternative embodiment, see  FIG. 6 , the gripping devices  24  are positioned on the free end portions of their respective springs  44 . The springs  44  are fixedly connected to the first attachment  18 . This simplified embodiment does however not have the same strength as the preferred embodiment, but may in some cases be relevant due to its reduced construction length.