Abstract:
This invention relates to a time controlled release device for down line tools in oil or gas wells. Tools that are lowered into a well for various purposes occasionally become stuck in the well and are not able to be withdrawn using jars and other dislodging techniques. In such a situation it is desirable to provide a controlled release device that will disengage the tool from the line only after a given time period. This allows the operator to continue to exert upward force on the line for a given time period prior to the release device being actuated.

Description:
BACKGROUND OF INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention pertains to mechanical devices used in wells such as oil and gas wells. More, particularly, a device is provided for releasing a line supporting a tool in a well from the tool if the tool becomes stuck in the well. A novel release collet mechanism for releasably connecting two members together is also provided. 
         [0003]    2. Description of Related Art 
         [0004]    A variety of mechanical devices or tools are used in wells, for such purposes as logging the properties of the rock around the well, taking samples of the rock, perforating holes in casing in the well and other purposes. Because of solids accumulating in an open hole or mechanical malfunctions in a cased hole, it may become impossible to retrieve a tool from a well with the line supporting the tool. The line may be a “slick line” or an electric wire line. In this situation it is desirable to release the line from the tool that is lodged in the well. 
         [0005]    Different mechanisms have been used for releasing a line from a stuck tool. For example U.S. Pat. No. 5,109,921 discloses a releasable tool with first and second shear pin arrangements. U.S. Pat. No. 5,568,836 discloses a release device having a latch mechanism and a time delay mechanism that is actuated after a time interval has elapsed. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention allows for the disconnection of a tool from a well line after a predetermined force has been applied for a predetermined time. This allows disengagement of the tool to be aborted up until the predetermined time. A locking mechanism may also be applied to prevent inadvertent or premature release of the tool. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0007]      FIGS. 1   a,    1   b,    1   c  and  1   d  illustrate a time delayed release device according to the present invention. 
           [0008]      FIG. 2  illustrates an alternative embodiment of the invention used in conjunction with a swivel mechanism for the lower portion of the tool. 
           [0009]      FIG. 3  shows the lower portion of the device that remains in the well after the release mechanism has been actuated. 
           [0010]      FIG. 4  shows the lower portion of the embodiment shown in  FIG. 2  that is left in the well after actuation of the release device. 
           [0011]      FIG. 5  shows the details of the release collet and sleeve mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    In the following description the term proximal is used to describe the portion of the part being referred to that is closest to the well opening and the term distal is used to refer to the portion of the part that is furthest from the well opening. 
         [0013]    Referring to  FIGS. 1   a  through  1   d,  there is shown an exemplary embodiment of a time-controlled release devise adapted to be inserted into a wellbore (not shown) according to the present invention. The outer housing or casing includes several different parts that are connected to each other. These include seal housing  12 , drive housing  13 , collet housing  14 , filling sub  15 , balance piston housing  17 , mud port housing  16 , balance housing  8 , release collet  31  and releasable housing portions  30  and  2 . The mandrel extends longitudinally within the casing and also includes several sections that are connected together. These sections include hammer mandrel  6 , collet mandrel  7 , balance mandrel  11 , and release sleeve mandrel  24 . 
         [0014]    The proximal portion of the device includes a mandrel connection pin  1  with threads located at its proximal end for securing the device to a wireline connector (not shown). Located partially within the mandrel connection pin is a contact plunger  66  surrounded by an insulating sleeve  67 . Ring  70  secures the insulating sleeve within bore in the mandrel connection Pin  1 . A spring contact  65  is located within the insulating sleeve and extends between the contact plunger  66  and a contact nut  64  which is secured to a conductor rod  56 . The conductor rod is surrounded by a tubular insulating sleeve  60 , which may be teflon tubing. 
         [0015]    An insulator cone  55  surrounds the conductor rod to insulate the contact nut  64  from the mandrel connection pin  1 . The distal end of the connection pin  1  has an internally threaded bore which receives the threaded outer portion of a hammer mandrel  6 . A drive housing  13  surrounds the mandrel  6  at a first proximal portion as show in  FIG. 1   b.  At the proximal portion of the drive housing  13 , an externally threaded seal housing  12  is threadedly received by internal threads on the inner surface of the drive housing  13  as shown in  FIG. 1   a.  The seal housing includes a seal disc  3  and a jam screw  46  as shown to allow for a fluid to be introduced into the interior of the tool. Located between the drive housing  13  and hammer mandrel  6  is a biasing element shown as a spring  38  comprising a stack of Belleville washers. The spring is initially held in compression between an annular surface on the distal end of seal housing  12  and a pressure piston  23  located within drive housing  13 . As can be seen in  FIGS. 1   a,    2  and  1   b,  a hydraulic chamber is formed by the drive housing  13 , seal housing  12 , and pressure piston  23 . The pressure piston includes a metering orifice  42  having a protective filter  32 . The piston and orifice act as a time delay as the mandrel moves upward (right to left looking at  FIG. 1   b ) as will be explained in more detail. 
         [0016]    The hammer mandrel portion  6  has an enlarged diameter section  401  with internal threads that receives an externally threaded portion of a collet mandrel  7 . Surrounding the collet mandrel is a filling sub  15 , which has external threads extending from opposite ends. The proximal threads are secured to an internally threaded portion of the drive housing  13  and the distal threads are secured to an internally threaded portion of the collet housing  14 . Filling sub  15  is provided with another seal disc  3  and jam screw  46  to allow introduction of a fluid to the interior of the release device at this point. A second biasing element shown as a stack of Belleville washers is located between the collet mandrel  7  and the collet housing  14 . One end of the biasing element abuts an end face of the filling sub  15  while the other end contacts a compression ring  9  as shown in  FIG. 1   b.  A locking collet  20  ( FIG. 1   c ) surrounds a portion of the collet mandrel  7  and is in turn surrounded by a trigger sleeve  21  located between the collet housing  14  and the locking collet  20 . A portion of collet mandrel  7  is provided with circumferentially extending grooves  402 . The details of the locking collet  20  and its operation are described in applicant&#39;s U.S. Pat. No. 6,481,495, the contents of which are hereby expressly incorporated herein. 
         [0017]    A balance piston housing  17  has a proximal portion externally threaded which engages a distal internally threaded portion of the collet housing  14 . The distal portion of the balance piston housing  17  is internally threaded to receive an externally threaded proximal portion of a mud port housing  16 . Mud port housing  16  has inlet ports  16   a  to allow liquid within the well to communicate with a chamber formed by opposing end faces of balancing pistons  27  and outer housing sections  17  and  16  as shown in  FIG. 1   c.  The distal portion of the mud port housing is internally threaded to receive the proximal portion of balance housing  8 . 
         [0018]    A first annular fluid chamber is formed between the collet mandrel  7  and balance piston housing  17 . Located within this chamber is an annular balance piston  27  which is slidably mounted on the collet mandrel  7 . A second fluid chamber is formed between the mud port housing  16  and the collet mandrel as shown in  FIG. 1   c  and has located therein a second annular balance piston  27 . An annular fluid passage that communicates between the first and second fluid chambers is formed between a reduced diameter portion of the mud port housing  16  and the collet mandrel  7 . The balance pistons act to balance pressure differentials due to variances in temperature and compressive pressure along the length of the release device. The details and operation of the balancing piston is fully described in applicant&#39;s U.S. Pat. No 7,290,604, the contents of which is hereby expressly incorporated herein. 
         [0019]    A balance housing  8  having an externally threaded proximal portion is secured to the distal threaded portion of mud port housing  16 . A distal portion of the balance housing  8  is internally threaded and receives the proximal externally threaded portion of a release collet  31  as shown in  FIG. 1   d.  The distal end portion of the collet mandrel  7  has an externally threaded portion that receives an internally threaded portion of balance mandrel  11 , which has a distal internally threaded portion that receives an externally threaded portion of a sleeve release mandrel  24 . A release sleeve  25  is slidably mounted on the sleeve release mandrel  24  between a retaining ring  48  and a wave spring  302 . The disconnect housing  30  is releasably attached to the release collet as shown in  FIG. 1   d.  Release collet  31  has a main body portion with an axial bore extending therethrough. A plurality of axially spaced flexible fingers  308  extend longitudinally from the main body portion. At the end of the fingers are located radially inwardly extending tabs  307  and raised contact shoulders. A release sleeve  25  slides within the axial bore of the collet  31 . The sleeve is provided with a plurality of axially spaced grooves  304  that are adapted to receive the tabs  307  located on the fingers of the collet  31 . When the sleeve travels a sufficient distance so that the grooves are in alignment with the tabs on the ends of the collet fingers, the fingers flex inwardly due to the forces acting on the raised contact shoulders, thus moving the contact surfaces  308  on the upper portion of the fingers from the contact surface  301  of the disconnect housing, thus allowing the parts retained in place by the contact surfaces to separate. At this point in time the release tool is disengaged from the tool(s) that are connected to the tool at  2 . Disconnect housing  30 , housing connection housing  2  and sliding contact rod  61  are left behind by virtue of being attached to the down well tool at the internal threads of connection housing  2  as shown in  FIG. 3 . 
         [0020]    Another feature of this invention, although not critical to its operation, is a mechanism that provides an indication that separation is about to occur. 
         [0021]    Located within the distal portion of collet mandrel  7  is an insulating bushing  47  for the conductor rod  56  as shown in  FIG. 1   d.  The distal end of release collet  31  has a reduced diameter portion over which the proximal portion of disconnect housing  30  is received. The distal portion of disconnect housing has an internally threaded portion that receives an externally threaded portion of housing connection  2 . The distal end portion of conductor rod  56  is connected to conductor barrel  51  which is surrounded by an insulating sleeve  49 . The distal end of the conductor barrel has an internal bore that receives a sliding contact rod  61 , which is connected to the connection housing as discussed below. An insulating sleeve  52  surrounds contact rod  61  and is located within a bore in release sleeve mandrel  24 . The proximal end of the sliding contact rod  61  caries two current carrying contact springs  201 . Suitable springs are sold by Bal Seal Engineering, Inc. and are known as BAL CONTACT SPRINGS. The downstream end of the sliding contact rod  61  is engaged by a rod holder  53  and by a rod holder and insulating bushing  54 . A Teflon insulator tubing  59  is located between the connector housing and the distal portion of rod holder  53 . A contact socket  62  is connected to the rod holder  53  to enable electrical connection to the down well tool carried by connector housing  2 . An insulating washer  58  is positioned between contact socket  62  and the interior of housing  2  as shown in  FIG. 1   d.  As the mandrel moves from right to left in  FIG. 1   d,  current carrying contact springs  201 , which are in contact with the conductor barrel, will eventually contact insulating sleeve  52 , resulting in an open circuit, thus indicating that the release is about to occur. The distance traveled by the springs when they come out of contact with conducting barrel is less than that required for the grooves on the release sleeve  25  to engage the tabs on the flexible fingers of the release collet  31 . This enables the operator to continue the release process or abort the process if desired before the release mechanism is actuated. 
         [0022]    In operation, force applied in an upward direction on the mandrel will cause the mandrel to move upwardly against the biasing force of the first and second springs and the piston  23  acting on the fluid in the chamber within drive housing  13  as shown in  FIG. 1 . After an initial force of, for example, 600 pounds, locking collet is moved sufficiently to permit the fingers of the locking collet to flex outwardly, thus allowing the mandrel to disengage from the collet. At this point a force of approximately 750 pounds is applied to the wire. Further movement of the mandrel is now resisted by the first spring and the pressure piston  23 . The metering orifice  42  in the piston acts to regulate the amount of time required to have the mandrel move sufficiently for the release collet to be activated. The delay time period can be varied by using orifices of different diameters and springs with different spring constants. When the mandrel has traveled the distance required to allow the grooves  304  in the outer surface of release sleeve  25  to mesh with the interior grooves in the fingers of release collet  31 , the fingers on the end of release collet move inwardly. This disengages the shoulders  308  on the fingers from the interior shoulder  301  formed in the bore of housing  30 . At this point the upper portion of the device is disengaged from the lower housing section, leaving it attached to the lower tool at  2 . Conductor rod connectivity is broken as the mandrel is traveling when current carrying contacts  201  are no longer in contact with conductor barrel  49 . This will give the operator an indication that separation is about to occur. Balancing pistons  27  are free to move along the mandrel to compensate for pressure differentials due to temperature differences and the compressive forces acting on the exterior of the tool. External fluid is allowed to enter the space between the two pistons via mud ports  16   a  in housing  16 . 
         [0023]    In some applications it is desirable to provide a swivel connection between the release device and the stuck tool. Such an arrangement is shown in  FIG. 2 . As show in  FIG. 2 , a swivel housing  33  is connected to the distal portion of disconnect housing  30  by screw threads. The distal portion of swivel housing  33  is in turn connected to a second seal housing  12 . The seal housing is provided with a seal disc and jam screw. Located within the swivel housing is a bearing mandrel  5 . Suitable bearings are located between the swivel housing and the bearing mandrel. A connector  57  connects contact rod  61  to conductor rod portion  56 . The distal end of bearing mandrel  5  is threadedly attached to the connector housing  2 , as shown in  FIG. 2 . Thus in the embodiment of  FIG. 2 , the release device is rotatably connected to the down well tool via connector housing  2  and bearing mandrel  5 .  FIG. 4  illustrates the portion of the release tool that is left in the well after separation of the embodiment of  FIG. 2 . 
         [0024]    Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.