Abstract:
Presented is a system and method for disconnecting a plurality of wireline tools from a string of wireline tools while maintaining operation of the wireline tools remaining with the string of wireline tools. The disconnection is non-destructive and allows a reconnection of the disconnected tools after retrieval from the well. The system also enables testing of the disconnection mechanism before deploying the wireline tool string into the well.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to down hole remotely operated oil well wireline tools and, more specifically, to a down hole wireline tool release mechanism. 
       BACKGROUND 
       [0002]    The ever increasing use of fossil fuels has led to the development of drilling technologies that were unimaginable in the recent past. For instance, the ability to drill a well to a desired depth and then steer the well, with respect to the drilling platform, from a vertical direction to a horizontal direction is now a common practice. The direction of a well can be changed based on factors such as the geological strata or a recovery design plan for optimizing the output from the well. 
         [0003]    The multidirectional drilling capabilities described above have introduced a new series of problems related to determining the operational parameters of the well. For example, a common task in the startup and operation of a well is to deploy one or more wireline tools down a well to collect data. The wireline tools can measure well parameters, employ cameras for optical observation or even perform radioactive irradiations to evaluate the localized geological strata. The key difference is in a well with a straight vertical direction and a well with an orientation that shifts from a vertical direction to a horizontal direction and possibly upwards towards the surface. 
         [0004]    As is easily imagined, retrieving a series of wireline tools from a well with changing direction of bore is more difficult than retrieving the same series of wireline tools from a straight vertical well. For example, the force of gravity combined with the bend of a turn in the well can cause a string of wireline tools to become stuck. This problem can occur either because one of the tools is physically stuck in a bend in the well or the force required to pull the series of wireline tools through the bend is greater than the tensile strength of the wire attached to the wireline tools. 
         [0005]    In another example, when perforating charges are detonated the perforation canister can deform during the explosion and become lodged in the well bore. As described above, the force required to retrieve the deformed perforation canister can exceed the tensile strength of the wire attached to the wireline tools. 
         [0006]    Under the above described circumstances, a system and associated methods are desired allowing the release of the wireline tools above the obstruction without disrupting the ability of the remaining wireline tools to continue performing their intended tasks as the tool string is removed from the well. Additionally, the ability to reconnect wireline tools without requiring replacement of all components retrieved from the well is desirable because the additional benefit of the ability to test a string of wireline tools before insertion into the well becomes possible. 
       SUMMARY 
       [0007]    Systems and methods according to the present invention address these needs by providing a multifunction down well release tool mechanism with a lost motion design and a flooding valve for disconnecting upper sections of the wireline tool string from lower sections of the tool string lodged in the well. After disconnection, the remainder of the wireline tool string, still attached to the wire, continues to function as the shortened string is removed from the well. The design also provides a nondestructive detachment allowing the wireline tool string to be reconnected with the remainder of the tool string removed from the well or to new elements of a tool string without replacing the elements of the tool string above the disconnect point. 
         [0008]    According to an exemplary embodiment, a linear motion motor-driven reciprocating shaft actuates all aspects of the release process. These aspects include but are not limited to releasing the latching clamps, disconnecting the electrical connections passed to the subsequent tools in the string and actuating the flooding valve for pressure equalization of the release chamber. 
         [0009]    According to another exemplary embodiment, a motor-driven rotating motion shaft rotates a cam mechanism that similarly actuates all aspects of the release process. As described above for the linear motion process, these aspects include but are not limited to releasing the latching clamps, disconnecting the electrical connections passed to the subsequent tools in the string and actuating the flooding valve for pressure equalization of the release chamber. 
         [0010]    In various embodiments, the lost motion included in the actuation stroke protects the drive train from large pressure forces exerted by the well fluid when the tool is released. Accordingly, the design is robust and durable allowing for the reconnection of either new tools or disconnected tools recovered from the well. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings illustrate exemplary embodiments, wherein: 
           [0012]      FIG. 1  depicts the release mechanism shown in the connected position, including the electric motor and the gearbox; 
           [0013]      FIG. 2  depicts an enlarged view of the release mechanism drive train chamber and release chamber shown in the connected position; 
           [0014]      FIG. 3  depicts an enlarged view of the release mechanism drive train chamber and release chamber shown with the leadscrew nut advanced to take up lost motion. 
           [0015]      FIG. 4  depicts an enlarged view of the release mechanism drive train chamber and release chamber shown with the flooding valve beginning to open and the latching dogs partially released. 
           [0016]      FIG. 5  depicts an enlarged view of the release mechanism drive train chamber and release chamber with the flooding valve open, the latching dogs released and the reciprocating shaft forced fully open by well fluid pressure in the release chamber. 
           [0017]      FIG. 6  depicts an enlarged view of the release mechanism drive train chamber and release chamber with the release mechanism fully released and the fishing neck disengaging. 
           [0018]      FIG. 7  depicts a method of disconnecting a fishing neck subassembly from a release mechanism. 
           [0019]      FIG. 8  depicts a method of reconnecting a fishing neck subassembly to a release mechanism. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. 
         [0021]    Looking first to  FIG. 1 , a detailed diagram of the release mechanism  100  according to an exemplary embodiment is illustrated. As discussed previously, the release mechanism  100  performs aspects of releasing one or more tools from the string of wireline tools. These aspects include, for example and not limited to, releasing the latching clamps  124 , disconnecting the electrical connections passed to subsequent tools in the string  116 / 118  and actuating the flooding valve  120  for pressure equalization of the release chamber  106 . 
         [0022]    In general, a release mechanism is comprised of a motor/gearbox assembly  102 , a drive train chamber  104  and its associated components, a release chamber  106  and its associated components, a flooding valve  120  separating the release chamber  106  from the outside well fluid, a sealed bulkhead  126  separating the drive train chamber  104  and the release chamber  106 , and a reciprocating shaft  108 . The reciprocating shaft  108  is functionally connected to the motor/gearbox assembly  102  through the leadscrew  110  and leadscrew nut  112  assemblies and simultaneously actuates, according to this exemplary embodiment, the electrical spring contact  116 , the latching dogs  124  and the flooding valve  120 . 
         [0023]    The drive train chamber  104  houses the leadscrew  110  and the leadscrew nut  112  in an open area of lost motion  114  of the reciprocating shaft  108 . The lost motion area  114  allows the reciprocating shaft  108  to strike the end of the drivetrain chamber  104  closest to the motor/gearbox  102  when the flooding valve  120  opens and the reciprocating shaft  108  is subjected to the full pressure of the well fluid. This protects the leadscrew  110  and the motor/gearbox  102  from damage. 
         [0024]    In another aspect, the end of the drive train chamber  104  adjacent to the flooding valve  120  provides a conductive ring  118  around the perimeter of the drive train chamber  104 . The conductive ring  118  provides power and data communications conductivity to the reciprocating shaft  108  for connection to additional wireline tools and release mechanisms  100  further along the wireline tool string. When the release mechanism is in the connected position, an electrical spring contact  116  engages with the conductive ring  118  providing a circuit for power and data communications connectivity. The electrical spring contact  116  is connected to the reciprocating shaft  108  and disconnects from the conductive ring  118  as the reciprocating shaft  108  begins to move towards the motor/gearbox  102 . 
         [0025]    A further aspect provides for a sealed bulkhead  126  that prevents well fluid from entering the drivetrain chamber  104  when the release mechanism  100  opens the flooding valve  120  and allows well fluid into the release chamber  106 . Similarly, seals at the release end of the reciprocating shaft  108  located around the sealed electrical connector  128 , prevent well fluid from entering the reciprocating shaft  108 . 
         [0026]    The release chamber  106  houses the fishing neck  122  and the latching dog  124  mechanism for retaining the fishing neck  122  in the release chamber  106  during connected operation. Only one latching dog  124  is shown in the section view of  FIG. 1 , However there is a plurality of latching dogs equal spaced around the axis of the tool. A conical latching dog actuator  130  is attached to the reciprocating shaft  108  and engages the latching dogs  124  when the reciprocating shaft  108  is in the connected position. When the reciprocating shaft  108  begins to move to the disconnected position, the conical latching dog actuator  130  is moved towards the flooding valve  120  and releases the latching dogs  124 . Once the latching dogs  124  have released, the reciprocating shaft  108  continues to move towards the disconnected position and the flooding valve actuating cylinder  132  presses on the flooding valve  120 , which causes it to move toward the sealing bulkhead  126 . Once the o-ring seal at the end of the flooding valve  120  closest to the latching dogs  124  disengages from its sealing bore, well fluid flows into the release chamber  106 , which equalizes the pressure in release chamber  106  with the ambient well pressure. Once well fluid has entered the release chamber  106 , the pressure forces both the flooding valve  120  and reciprocating shaft  108  towards the motor/gearbox  102 . Lost motion has been incorporated into both of these mechanisms so that, when they are subjected to well pressure, they are supported by suitably strong structural components. This protects the leadscrew  110 , motor/gearbox  102  and other delicate actuating components from damage. With pressure equalized on the inside and the outside of the fishing neck  122 , the release chamber  106  can easily be pulled from around the fishing neck  122  completing the disconnection. 
         [0027]    The seals on the flooding valve  120  at the end closest to the drive train chamber  104  remain engaged to ensure that the flooding valve  120  is driven by well pressure into the fully open position, therefore accelerating the flooding process and also protecting the more delicate actuating components from damage. 
         [0028]    In another aspect of release mechanism  100 , an electric motor  102  rotates a leadscrew  110  through a high ratio gearbox  102 . The leadscrew  110  drives a leadscrew nut  112  either up or down the axis of the reciprocating shaft  108 . When the leadscrew nut  112  is driven away from the motor/gearbox  102  to the end of travel, the wireline tool attached to the fishing neck  122  is connected. When the leadscrew nut  112  is driven towards the motor/gearbox  102  to the end of travel, the wireline tool attached to the fishing neck  122  is released. Of course those skilled in the art will recognize that according to other, alternative exemplary embodiments it may be possible to reverse the relationship between the direction in which the leadscrew nut  112  is driven and the connected/released mode of the fishing neck  122 . 
         [0029]    The leadscrew nut  112  is captive within a contained area of the reciprocating shaft  108  but is not held rigidly according to this exemplary embodiment. The release mechanism design  100  includes free space on either side of the leadscrew nut  112  producing lost motion  114  or backlash in the actuating stroke. The reciprocating shaft  108  passes through a sealed bulkhead  126 , which defines two different chambers within the release mechanism  100 . The drive train chamber  104 , on the motor/gearbox  102  side of the sealed bulkhead  126  is never entered by well fluid. The release chamber  106 , on the other side of the sealed bulkhead  126  from the drive train chamber  104  becomes flooded with well fluid when a wireline tool disconnect is performed. 
         [0030]    In the drive train chamber  104 , the reciprocating shaft  108  is held within an insulated housing fitted with a conductive ring  118  at the end near the sealed bulkhead  126 . When the reciprocating shaft  108  is in the connected position, the reciprocating shaft  108  is aligned such that an electrical spring contact  116  is in conductive contact with the conductive ring  118 . This allows electrical power and data communications through the center of the reciprocating shaft  108  to the wireline tool attached to the fishing neck  122 . When the reciprocating shaft  108  begins to move to the released position, the electrical spring contact  116  is pulled away from the conductive ring  118 , thereby breaking the electrical and data communication connection to the exposed end of the reciprocating shaft  108  and the wireline tools connected to the fishing neck  122 . This allows tools located above the release tool to continue operating after a tool disconnect is perform. 
         [0031]    In the release chamber  106 , the reciprocating shaft  108  passes through the center of a flooding valve  120  then enters through the top of a fishing neck  122  subassembly. At the other end of the fishing neck  122  subassembly are three latching dogs  124 . The latching dogs  124  are used to hold the fishing neck  122  subassembly in the release chamber  106 . The latching dogs  124  are driven into the latched position by the conical dog actuator  130  attached to the reciprocating shaft  108 . When the reciprocating shaft  108  is in the connected position, the cone of the conical dog actuator  130  pushes outwards on the inside faces of the latching dogs  124 , holding them locked into the release chamber  106  housing. As the reciprocating shaft  108  is moved to the released position, the conical dog actuator  130  is pulled out from under the inside faces of the latching dogs  124 , allowing them to drop out of the locking sleeve in the release chamber  106  and releasing the fishing neck  122  subassembly from the release chamber  106 . 
         [0032]    In another aspect, loosely positioned around the reciprocating shaft  108  between the flooding valve  120  and the conical dog actuator  130  is the flooding valve actuating cylinder  132 . As the reciprocating shaft  108  moves to the released position, the flooding valve actuating cylinder  132  becomes trapped between the conical dog actuator  130  and the flooding valve  120  and pushes the flooding valve towards the sealed bulkhead  126 . Once the seal on the flooding valve  120  exits the seal bores in the release chamber  106  wall, well fluid is allowed to enter the release chamber  106 . The flooding valve  120  also has lost motion on either side, allowing it to move rapidly to the flooding position as well fluid begins to enter the release chamber  106 . 
         [0033]    In another embodiment, the fishing neck  122  subassembly with its associated wireline tools is reconnected to the to the release mechanism  100  by manually pushing the fishing neck  122  subassembly into the release chamber  106 . The motor/gearbox  102  is then run in the reverse direction from a disconnect operation. The leadscrew nut  112  first takes up the lost motion in the opposite direction. After the lost motion is recovered, the reciprocating shaft  108  is then pushed in the direction of the release chamber  106 . The lost motion of the flooding valve  120  is now recovered and the flooding valve  120  is pushed to the closed position. As the reciprocating shaft  108  reaches the end of travel, the flooding valve  120  has completely closed, the conical dog actuator  130  forces the latching dogs  124  back into the locking sleeve in the release chamber  106  and the electrical spring contact  116  engages with the conductive ring  118  restoring power and data communications to wireline tools further along the wireline tool string. Although both the reciprocating shaft  108  and the flooding valve  120  experience lost motion while moving, both are driven to hard stops when in the connected position. This hard stop lockup prevents either from moving accidentally under the effects of shock or vibration. 
         [0034]    Looking now to  FIG. 2 , an enlarged partial view of the release mechanism  100  is shown in the connected position. The leadscrew nut  202  is against the hard stop, locking the reciprocating shaft  204  in place to prevent any accidental disconnect from jarring or vibration. The electrical spring contact  208  is in contact with the conductive ring  210 , therefore providing electrical power and data communication connectivity to any wireline tools attached to the fishing neck  122  subassembly. The flooding valve  206  is in the fully closed position and also resting against a hard stop to prevent accidental opening. Finally, the conical dog actuator  212  is engaged with the latching dogs  214  forcing them into a locked position in the locking sleeve  216  of the release chamber  106 . 
         [0035]      FIG. 3  illustrates an enlarged partial view of the release mechanism  100  at the beginning of the disconnect cycle where the leadscrew  302  has rotated to the point where the leadscrew nut  304  has taken up all the lost motion in the reciprocating shaft  306 . At this point, further rotation of the leadscrew  302  will result in movement of the reciprocating shaft in the disconnect direction. 
         [0036]    Looking now to  FIG. 4 , an enlarged partial view of the release mechanism  100  illustrates the reciprocating shaft  406  traveling in the disconnect direction with contact broken between the electrical spring contact  402  and the conductive ring  404 . At this point power and data connectivity is no longer provided to any wireline tools connected to the fishing neck  122  assembly or any other wireline tools further down the wireline tool string. The conical dog actuator  412  is disengaging the latching dogs  414  allowing release of the fishing neck  122  assembly from the release chamber  106 . The flooding valve actuating cylinder  410  is just beginning to make contact with the flooding valve  408 . It should be noted that all power connections traversing the release chamber  106  are disconnected before the flooding valve  408  begins to move and allows well fluid into the release chamber  106 . 
         [0037]      FIG. 5  depicts an enlarged partial view of the release mechanism  100  showing a complete disconnect. The reciprocating shaft  502  has reached its maximum disconnect travel location. The flooding valve  504  is in its fully open position and latching dogs  506  are fully released. It should be noted that after releasing the fishing neck  122  subassembly the remaining wireline tools above the release mechanism  100  continue to function in their normal manner and can continue to collect data as they are removed from the well hole. 
         [0038]    Looking now to  FIG. 6 , an enlarged partial view  600  of the release mechanism  100  illustrates the disconnected release mechanism  100  being pulled from the fishing neck  602  subassembly. After retrieval of the fishing neck  602  subassembly and its attached wireline tools, the fishing neck  602  subassembly and its attached wireline tools can be reconnected to the disconnected release mechanism  100  and reinserted into the well. 
         [0039]      FIG. 7  illustrates the method  700  of disconnecting the release mechanism  100  from the fishing neck  602  subassembly. Beginning at step  702 , the leadscrew  110  is actuated to recover the lost motion by driving the leadscrew nut  112  to the uphole end of the drivetrain chamber  104 . The leadscrew  110  can be actuated by any power transferring device such as an electric motor and gearbox assembly  102 . After the leadscrew nut  112  reaches the end of its travel, the method proceeds to step  704 . 
         [0040]    At step  704 , all lost motion is recovered and the reciprocating shaft  108  begins to retract towards the uphole end of the release mechanism  100 . The initial reciprocating shaft  108  retraction simultaneously disconnects power and data connectivity through the release chamber  106  by separating the electrical spring contact  116  from the conductive ring  118  and disengages the latching dogs  124  by moving the conical dog actuator  130  towards the uphole end of the release mechanism  100 . After the power is disconnected and the latching dogs  124  are released, the method proceeds to step  706 . 
         [0041]    Continuing at step  706 , the reciprocating shaft  108  continues retracting and opens the flooding valve  120  allowing well fluid into the release chamber  106 . As the high pressure well fluid enters the release chamber  106  the method proceeds to step  708  and the reciprocating shaft  108  and the flooding valve  120  are forced to the protective hard stop at the uphole end of the drivetrain chamber  104 . The flooding valve  120  is now fully open and the entering well fluid has equalized the pressure on the inside and outside of the release chamber  106 . Finally, at step  710 , the release mechanism  100  can be pulled from the fishing neck  602  subassembly allowing removal of the remaining functional wireline tools and providing access to the fishing neck  602  subassembly for attachment of a cable suitable to pull the disconnected wireline tools from the well hole. 
         [0042]    Looking now to  FIG. 8 , a method of connecting a fishing neck  602  subassembly to a release mechanism  100  is illustrated. Beginning at step  802 , the fishing neck  602  subassembly is inserted into the release chamber  106  until fully seated. Next, at step  804 , lost motion is taken up by actuating the leadscrew  110  until the leadscrew nut  112  seats against the reciprocating shaft  108  at the uphole end of the reciprocating shaft. 
         [0043]    Continuing to step  806 , the reciprocating shaft begins extending towards the downhole end of the release mechanism  100  and drives the flooding valve to the fully closed position. Next at step  808 , further extending the reciprocating shaft towards the downhole end of the release mechanism engages the latching dogs  124  into the fishing neck  602  subassembly and forces the electrical spring contact  116  against the conductive ring  118 . This step results in a mechanical lockup of the fishing neck  602  subassembly and the release mechanism and provides electrical and data connectivity to the wireline tools connected to the fishing neck  602  subassembly. The wireline tool string is now prepared for insertion into the well hole. 
         [0044]    The above-described exemplary embodiments are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in detailed implementation that can be derived from the description contained herein by a person skilled in the art. All such variations and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items.