WO2023279192A1

WO2023279192A1 - Running and retrieval tool

Info

Publication number: WO2023279192A1
Application number: PCT/CA2022/000033
Authority: WO
Inventors: George James Michaud; Stewart George WILSON; Charles Erle Norvila; Colin Walter Brock; Jeff Skands
Original assignee: Beyond Energy Services And Technology Corp.
Priority date: 2021-07-09
Filing date: 2022-07-07
Publication date: 2023-01-12
Also published as: CN117581005A; CA3124148A1; GB202318983D0; EP4367362A1; AU2022306881A1; GB2622176A; CA3222380A1

Abstract

A running-retrieving tool for use in oilfield operations, said tool comprising: a first section comprising a bonnet and a split retainer, said first section comprising a cavity having an inner diameter adapted to allow the insertion therethrough of a second section and wherein said first section is adapted to be secured to a tool (such as a bearing assembly); and said second section having an elongated body having an external diameter smaller than the internal diameter of said first section, said second section comprising: a track adapted to secure a retaining means extending from said split retainer thereinto; an entry channel adapted to receive said retaining means positioned on said first section; a release channel adapted to allow said retaining means to be released from said track; wherein said second section being adapted to be mounted onto a drillstring or the like and being releasably insertable inside said cavity of said first section through the insertion of said retaining means inside said track.

Description

RUNNING AND RETRIEVAL TOOL m i ll OF THE INVENTION

The invention is directed to a novel tool used in the oil and gas industry, and more particularly it is directed to a novel running-retrieval tool.

BACKGROUND OF THE INVENTION

It is common practice to run, land, set and retrieve downhole tools within the borehole of a well to perform various functions including sealing the bore of the well or for carrying a measuring device for monitoring parameters such as pressure or temperature within the well. Typically, the borehole of a well is cased using drillpipe, casing or tubing string which is designed in such as way as to provide predetermined locations for landing and setting such downhole tools.

Running and retrieval tools are commonly used in the industry have a J-Slot profile used broadly in the industry. However the J-slot profile is not very user friendly in that there is typically a process where you encounter the entry profile of the J Slot by setting down and turning the tool rotationally until the Pin that engages the J-Slot, drops down then you continue to move downwards until the tool stops and then you turn again to engage the J profile to retrieve the tools

Other rotating control devices (RCDs) use mechanisms that require sheer pins to be utilized and are sheared as part of the function of installation and retrieval of tools. Again, this also is not user-friendly and requires the operator to continually perform maintenance in replacing the sheer pins. There are other designs that use air or hydraulics which actuate the tool from surface via hoses and a control console. However, this adds time to the process, risk in hoses getting pinched, and unnecessary cost in equipment and NPT.

A running tool is used to land and set other downhole tools in a well. Once the downhole tool is set in place, it may be left there for a period of time ranging from hours to several days. In the meantime, the running tool is brought back to the surface.

Running tools and downhole tools have been designed to be lowered, manipulated and retrieved using a ‘wire line’ or a single strand non-electric cable known as ‘slickline’. However, all of the currently used running-retrieval tools use the same type of connection. These connections allow the running tool to securely carry the tool or assembly to a predetermined location and subsequently release the tool and be brought back to the surface while the tool or assemble remains in place inside the wellbore. Once it is time to retrieve the tool or assembly, the running tool is run back downhole and attempts to ‘re-connnect’ with the tool at the connection point. Given the type of connection used, it requires some extremely precise navigating of the running tool to engage the connection and thus be able to remove the tool or assembly from its set position and bring it up to the surface of the wellbore.

In light of the current state of the art with respect to the connections for running -retrieval tools, there still exists a need to provide for a more durable, user-friendly connection. The present invention aims at overcoming at least some of the drawbacks currently encountered.

The present invention overcomes some of the prior art drawbacks by providing a running-retrieval tool which is user-friendly in that it the j -pins self-locate with complementary mating profiles by simple up and down movements of the tubular.

According to an aspect of the present invention, there is provided a running-retrieval tool for use in oilfield operations, said tool comprising: a first section comprising a bonnet and a split retainer, said first section comprising a cavity having an inner diameter adapted to allow the insertion therethrough of a second section and wherein said first section is adapted to be secured to a tool (such as a bearing assembly); and said second section having an elongated body having an external diameter smaller than the internal diameter of said first section, said second section comprising:

- a track adapted to secure a retaining means extending from said split retainer thereinto;

- an entry channel adapted to receive said retaining means positioned on said first section;

- a release channel adapted to allow said retaining means to be released from said track; wherein said second section being adapted to be mounted onto a drillstring or the like and being releasably insertable inside said cavity of said first section through the insertion of said retaining means inside said track. According to a preferred embodiment of the present invention, the retaining means comprise a plurality of J-pins extending radially inwardly from said first section and adapted to fit within said track located on said second section.

According to a preferred embodiment of the present invention, said track comprises an upper lifting shoulder and a lower shoulder portion and a channel located therebetween, wherein said upper lifting shoulder and lower shoulder portion can be separated from one another upon exertion of pressure onto the lower shoulder portion by said retaining means.

According to a preferred embodiment of the present invention, said lower shoulder portion of the track comprises a plurality of channel entry points adapted to direct a corresponding plurality of retaining means into the track. Preferably, the plurality of channels are funnel-like entry points.

According to a preferred embodiment of the present invention, the upper lifting section of the track comprises:

- a plurality of angled wall sections, each angled wall section comprising a lower end and an upper end and;

- a nesting gap located at said upper end of each one of said plurality of angled wall sections, wherein said nesting gap adapted to secure said retaining means during operation when said tool is travelling in a downward direction inside a wellbore.

According to a preferred embodiment of the present invention, during operation, upon exertion of a sufficient pressure on the lower shoulder portion of said track, the lower shoulder portion will separate by moving longitudinally away from said upper lifting shoulder thereby creating a plurality of release channels (exit points) associated with corresponding retaining means to release said second section from said first section and leave the first section at a pre-determined location within the wellbore.

According to another preferred embodiment of the present invention, said lower shoulder portion and said upper lifting portion comprise, at their meeting edge, a complimentary nesting profile adapted to maintain said lower should portion and upper lifting portion in place during rotational movement of a drillstring. Preferably, said complimentary nesting profile comprises a crenellated pattern.

According to a preferred embodiment of the present invention, said lower shoulder portion has a plurality of projections which combine with a plurality of complimentary projections located on a lower portion of the lifting shoulder of the track to form said plurality of funnel-like entry points. Preferably, said entry channel comprises a first side member located on a first side of said channel and a second side member located on a second side of said channel, wherein each of member being angled towards a track entry point. Preferably, said first side member being stationary and wherein said second side member being comprised of: an upper part which is stationary and a lower part which is movable.

According to a preferred embodiment of the present invention, said upper part of said second side member being located on said upper lifting shoulder of said track and said lower part of said second side member being located on said lower shoulder portion of said track.

According to a preferred embodiment of the present invention, said nesting gap is a semi-circular opening adapted to secure in place the bearing assembly to the running -retrieval tool. Preferably, said retaining means nesting gap is offset from said entry channel

According to a preferred embodiment of the present invention, said nesting gap comprises, on a first adjacent side, an angled wall to allow the upward movement of said retaining means to be directed the channel towards said nesting gap. Preferably, said nesting gap comprises, on a second adjacent side a wall parallel to a longitudinal axis of said drillstring.

According to another aspect of the present invention, there is provided a running-retrieval tool for use in oilfield operations, said tool comprising: a first section comprising a bonnet and a split retainer, said first section comprising a cavity having an inner diameter adapted to allow the insertion therethrough of a second section and wherein said first section is adapted to be secured to a tool (such as a bearing assembly); and said second section having an elongated body having an external diameter smaller than the internal diameter of said first section, wherein said first and said second section are releasably secured together in operation by a plurality of concentrically directed J-pins located on said first section engaging with a track located on said second section.

According to a preferred description of the present invention, there is provided a running and retrieval tool used to deploy and retrieve a bearing assembly (BA) to/lfom a RCD housing in offshore applications. Preferably, there are dual redundant safety feature which the other tools do not offer in that when the RRT is racked back in the derrick it is impossible for it to release itself and fall down to the rig floor due to the profile geometries of the tracks in addition to the split ring which requires a force of +/- 10,000 lbs to disengage the tool.

According to a preferred embodiment of the present invention, there is provided a J-track running and retrieval tool which is compact, simple, and user-friendly while offering features which enhance its safety during operations.

According to a preferred embodiment of the present invention, there is provided a running-retrieval tool which does not require to the rotation of the drill string in either clockwise or counter clockwise rotation for any reason (connecting or releasing a tool), only an axial movement up and down can achieve all the desired functions. With the conventional J-Slot configuration in a pressure control situation you may need to manipulate the annular pressure lower to allow for rotation of the drill string to align the j-slot and tool which could result in leakage between the drill pipe and annular. As it is well known, the annular was designed for mainly stripping applications in pressure control situations if required. With the ability of only requiring axial movement, there no longer exists a need to manipulate the annular pressure to operate the tool which results in an added safety feature.

BRIEF DESCRIPTION OF DRAWINGS

The invention may be more completely understood in consideration of the following description of various embodiments of the invention in connection with the accompanying figures, in which:

FIG. 1 is a side view of a prior art running-retrieval tool link;

FIG. 2 is a cross-sectional side view of a running-retrieval tool link according to a preferred embodiment of the present invention;

FIG. 3 is a close-up of the cross-sectional side view of a running-retrieval tool link of Figure 2 according to a preferred embodiment of the present invention;

FIG. 4 is a perspective view of the bonnet and split retainer mounted on a bearing assembly according to a preferred embodiment of the present invention;

FIG. 5 is a close up perspective view of the bonnet and split retainer mounted on a bearing assembly according to a preferred embodiment of the present invention;

FIG. 6 is a perspective view of the mandrel comprising the J-track according to a preferred embodiment of the present invention;

FIG. 7 is a close up perspective view of the mandrel comprising the J-track according to a preferred embodiment of the present invention; FIG. 8 is a side view of the mandrel comprising the J-track according to a preferred embodiment of the present invention mounted on a tubular;

FIG. 9 is a side view of the bonnet and split retainer having a bearing assembly mounted thereon and inserted onto the mandrel comprising the J-track according to a preferred embodiment of the present invention;

FIG. 10a to FIG. lOd are side views of the bonnet and J-track at different points of insertion of the J-pin within the J-track according to a preferred embodiment of the present invention.

PI I LII ΐ h DESCRIPTION OF THE PREFERRED EMBODIMENT

According to a preferred description of the present invention, there is provided a running and retrieval tool used to deploy and retrieve a bearing assembly (BA) to/lfom a RCD housing in offshore applications. Preferably, it is compatible with 5-1/2 through to 6-5/8 drill strings together with 7-3/4” or 9” through bore bearing assemblies. According to a preferred embodiment, other than for the mandrel, bonnet and centralizer, all components are common throughout these size ranges.

Preferably, when in operation the tool stabs through the bearing assembly, leaving the mandrel’s box end above the bearing assembly and the mandrel’s pin end residing below the bearing assembly’s lower sealing element. Both ends of the mandrel are threaded, as per customer requirements, to make-up directly to the drill string (100). Being the primary tensile load bearing component of the tool, the mandrel is designed and manufactured to meet or exceed the tensile strength of the drill string.

During deployment, the tool (50) supports the weight of the bearing assembly (60) by means of the lock ring. The lock ring latches into a groove formed between the bonnet (3) and split retainer (4). To assemble, the tool (50) is stabbed through the bearing assembly (60) until the Split J-Profile’s lower shoulder contacts the bonnet’s no-go. With the tool in this position, the Split Retainer (4) engages with the top of the bonnet (3), thus retaining the lock ring (7) in its latched position.

As illustrated in Figures 8 and 9, the drill string (100) comprises the running tool (50) (see Figure 8) and the RCD (60) mounted on the bonnet (3) and split retainer (4) inside which the running tool is secured (see Figure 9).

As illustrated in Figures 4 and 5, the bonnet (3) comprises a split retainer (4), a plurality of evenly spaced apart and circumferentially positioned J-pins (8) which will create the link between the bonnet and the split retainer (4). Also found on the bonnet (3) are a plurality of cup point set screws (14) as well as steel hoist rings (22) and threaded rods (11) and nuts (12) to secure the split retainer (3) to the bonnet (3).

As illustrated in Figures 6 and 7, the running tool (50) comprises a split J-profile (10) made up of two sections (10a) and (10b) which, in operation, are interlocked with one another with a complementary crenellated profile. Also found on the running tool are a lock ring (7), a J-profile split cap (6), a split centralizer (1), a split shear ring (9), brass button heads (13) and a plurality of various screws (15, 16, 17, 18, 20, 21).

In operation, the running tool (50) is deployed by lowering the drill string (100) until the bearing assembly (60) seats inside the RCD Housing. Once the bearing assembly (60) is secured within the RCD housing, the drill string (100) is lifted such that the lock ring (7) disengages from the bearing assembly (60), requiring 10,000 lbf overpull. Lifting continues until the J-Pins (8), which protrude radially inward through the bonnet (3), contact the Split J-Profile’s lifting surfaces (40). At this time, the bearing assembly’s (60) securement can be verified by conducting an overpull. Next, the drill string (100) is again lowered until the Split J-Profile’s lower shoulder (80) contacts the bonnet’s no-go. At this point, the J-Pins (8) have advanced to the J-Profile’s release path. Finally, the drill string (100) is lifted, withdrawing the J-Track Running Tool (50) from the now deployed bearing assembly (60). Continued lifting returns the running tool (50) to the rig floor where it can be detached from the drill string (100) and set aside for later retrieval of the bearing assembly (60).

To retrieve the bearing assembly (60), the J-Track running tool (50) is again attached to the drill string (100) and then lowered. Prior to the J-Track running tool’s split J-profile (10) enters the bonnet (3), the mandrel’s (5) centralizer (1) ensures adequate concentricity. Further lowering of the splut J-profile (10) leads the J-Pins (8) to contact the guide surfaces (1030 and 1032) of the split J-profile (10). Upon contact of the J-pins (8) onto the guide surfaces (1030 and 1032) the forces exerted thereonto forces the rotation of the split J-profile (10) into a favorable alignment with the J-Pins (8).

According to a preferred embodiment of the present invention, the point of insertion of the J-pin into the j-track is defined as a channel adapted to direct the J-pin from a first lower position located outside the J-track to a second higher position located within the J-track. Preferably, the channel provides for two members (one on each side of the channel) each of which being angled towards the point of insertion similarly to a funnel. According to yet another preferred embodiment, the channel comprises a first and a second side members, wherein said first side member is stationary and wherein said second member is movable. According to the embodiment illustrated in the Figures 2 to 10, the second member is partially located on the split J-profile lower shoulder and separates from the other portion of the second member when sufficient pressure is exerted on the split J-profile lower shoulder. Upon entry through the point of insertion, the J-pin is directed to a nesting point where the J-pin reside in a semi-circular opening adapted to secure in place the bearing assembly to the running-retrieval tool. The J-pin nesting point is preferably offset from the channel so as to prevent the tool from slipping and losing the bearing assembly during a retrieval operation. Preferably, the J-pin is directed to the nesting point by an angled wall which angles the movement of the J-pin into the nesting point. Preferably, on the other side of the nesting point, the wall is parallel to the length of the tube.

According to the preferred embodiment illustrated, the second member is substantially aligned with the nesting point and is angled downwards to direct the J-pin, in a release operation, towards a point of contact defined as a point where the lower portion of the second member of the channel abuts with the first member of the adjoining channel. During a release operation, the pressure exerted by the J-pin on the point of contact will force downward movement of the split retainer and preferably, a forced partial rotation of the split retainer, resulting in the release of the J-pin from the running-retrieval tool and therefore release of the bearing assembly from the running-retrieval tool.

According to the preferred embodiment illustrated the second member of a channel abuts to the first member of the adjoining channel which directs the immediately adjoining J-pin into the adjoining channel.

According to the preferred embodiment of the present invention and as illustrated in Figures 10a- lOd), the point of insertion of the J-pin into the j-track (1020) is defined as a channel (1010) adapted to direct the J-pin (8) from a first lower position (illustrated in Figure 10a) located outside the J-track to a second higher position (illustrated in Figure 10b) located within the J-track (1020). Preferably, the channel (1010) provides for two members (one on each side of the channel)(1030 and 1032) each of which being angled towards the point of insertion similarly to a funnel. According to yet another preferred embodiment, the channel (1010) comprises a first and a second side members, wherein said first side member (1030) is stationary and wherein said second member is comprised of two parts, an upper part (1034) which is stationary and a lower part (1036) which is movable. According to the embodiment illustrated in the Figures 2 to 10, the second member (1032) is comprised of two parts (1034 and 1036). The lower part (1036) of the second side member (1032) is located on the split J-profile lower shoulder and separates from the other portion (1034) of the second member (1032) when sufficient pressure is exerted on the split J- profile lower shoulder. Upon entry through the point of insertion (channel (1010), the J-pin (8) is directed to a nesting point (or nesting gap) (1040) where the J-pin (8) resides in a semi-circular opening adapted to secure in place the bearing assembly to the running -retrieval tool. The J-pin (8) nesting gap (1040) is preferably offset from the channel (1010) so as to prevent the tool from slipping and losing the bearing assembly during a retrieval operation. Preferably, the J-pin (8) is directed to the nesting gap (1040) by an angled wall (1050) which angles the movement of the J-pin (8) as it crosses the channel upwards towards the nesting gap (1040). Preferably, on the other side of the nesting gap (1040), the wall (1060) is parallel to the length of the drill string or tubing.

According to the preferred embodiment illustrated, the second member (1032) is substantially aligned with the nesting gap (1040) and is angled downwards to direct the J-pin (8), in a release operation (see Figures 10c and lOd), towards a point of contact (1070) defined as a point where the lower portion (1036) of the second member (1032) of the channel (1010) abuts with the first member (1030) of an adjoining channel. During a release operation, the pressure exerted by the J-pin (8) on the point of contact (1070) will force a downward movement of the split retainer (4) and preferably, a forced partial rotation of the split retainer (4) which in turns creates a release channel (1080) resulting in the release of the J-pin (8) from the running-retrieval tool and, therefore, the release of the bearing assembly from the running-retrieval tool (50).

Continued lowering brings the lock ring (7) into latching engagement with the split retainer (4) and, finally, the split J-Profile’s lower shoulder (10b) contacts the bonnet’s no-go (###) lifted. According to a preferred embodiment of the present invention and under normal circumstances, the force required to withdraw the bearing assembly (60) from the RCD Housing will not exceed 10,000 lbf, which is the lock ring’s (7) release force, and will therefore be conveyed to surface with the Lock Ring supporting the BA’s weight. Should the bearing assembly (60) withdrawal force exceed 10,000 lbf, the lock ring (7) will disengage from the split retainer (4) and the J-Pins (8) will subsequently contact the Split J-Profile’s lifting surfaces (40). In this position, the required withdrawal force is transmitted from the Split J-Profile’s lifting surfaces (40) to the J-Pins (8). As long as the required withdrawal force does not exceed the pre-configured shear capacity of the split shear ring (9), the bearing assembly (60) will be withdrawn from the RCD Housing and conveyed back to the rig floor. If the withdrawal force exceeds the shear capacity of the split shear ring (9), the split shear ring (9) will shear downward and rotate clear of the J-Pins (8) permitting conveyance of the J-Track running tool (50) back to the rig floor. Once back on the rig floor, operators can re-secure the split shear ring (9) with an increased shear capacity (more and/or stronger shear elements), and then can proceed to conduct another retrieval attempt. According to a preferred embodiment as shown in Figures 2 to 10, the Split J-Profile’s (10) upper portion (10a) lifting surfaces (40) comprise an aperture shaped in a half circle adapted to receive the J-pins (8) and temporarily lock them in place during a lifting operation as pressure is applied upwards by the J- pins into their respective apertures. This nesting shape arrangement substantially reduces the risk of the J- pins slipping out of position and rotation and subsequent loss of the bearing assembly (60) while it is being pulled out of the hole.

According to a preferred embodiment of the present invention, this tool you does not require the drill string to be rotated in either clockwise or counter clockwise rotation for any reason strictly axial movement up and down for all functions.

With the conventional J-Slot configuration in a pressure control situation, it may be necessary to manipulate the annular pressure lower to allow for rotation of the drill string to align the j -slot and tool which could result in leakage between the drill pipe and annular. As it is well known in the field, the annular was designed for mainly stripping applications in pressure control situations if required. According to a preferred embodiment of the present invention, by only needing axial movement it is not necessary to manipulate the annular pressure to operate the tool which results in an added safety mindset.

Technical Description

According to a preferred embodiment of the present invention, the J-Track Running Tool consists of the following major components: a bonnet; a split retainer;

According to a preferred embodiment of the present invention, the bonnet has, for function, to attach to the top of bearing assembly and provide interface for deployment and retrieval of BA. Typically a bonnet is made from alloy steel, with a nitride finish. In the embodiment described above it weighs approximately 230 lbs.

According to a preferred embodiment of the present invention, the split retainer has, for function, to attach to the top of bonnet where it forms an internal groove into which lock ring latches and unlatches during deployment and retrieval operations. Typically, and according to this embodiment the split retainer is made of alloy steel with a nitride finish. According to a preferred embodiment of the present invention, the J-Pin has, for function, to transfer axial load between Bonnet and Split J-Profile. Typically, and according to this embodiment the J- pin is made of alloy steel with a nitride finish.

According to a preferred embodiment of the present invention, the Mandrel has, for function, to provide means of connecting running tool to drill string. Typically, and according to this embodiment the mandrel is made of alloy steel with a Rilcoat finish (middle body region only).

According to a preferred embodiment of the present invention, the Split Centralizer has, for function, to improve the concentricity/alignment preceding tool stab-in. Typically, and according to this embodiment the split centralizer is made of aluminum.

According to a preferred embodiment of the present invention, the J-Profile Split Cap has, for function, to captivate the Lock Ring. Typically, and according to this embodiment the J-Profile split cap is made of alloy steel with a nitride finish.

According to a preferred embodiment of the present invention, the Lock Ring has, for function, during deployment, to prevent cycling of J-Profile until the bearing assembly is seated. Reduces J-Pin wear and bearing damage during retrieval operations. Typically, and according to this embodiment the lock ring is made of alloy steel with a Rilcoat 4 finish.

According to a preferred embodiment of the present invention, the Split J-Profile has, for function, to provide bearing surfaces to lift the bearing assembly via J-Pins. Typically, and according to this embodiment the split J-profile retainer is made of alloy steel with a nitride finish.

According to a preferred embodiment of the present invention, the split shear ring to provide an emergency means of withdrawing tool from the bearing assembly. Preferably, it has total of 10 available locations, permitting installation of 2, 4, 6, 8 or 10 shear screws. Typically, and according to this embodiment the split shear ring is made of alloy steel with a nitride finish.

According to a preferred embodiment of the present invention, the button head screws, 5/8”-ll, 0.75” long has, for function, to act as a shear element. Typically, and according to this embodiment the split retainer is made of brass or alloy steel. While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by tbose skilled in tbe relevant arts, once they have been made familiar with this disclosure that various changes in form and detail can be made without departing from the true scope of the invention in the appended claims.

Claims

1. A running-retrieving tool for use in oilfield operations, said tool comprising: a first section comprising a bonnet and a split retainer, said first section comprising a cavity having an inner diameter adapted to allow the insertion therethrough of a second section and wherein said first section is adapted to be secured to a tool (such as a bearing assembly); and said second section having an elongated body having an external diameter smaller than the internal diameter of said first section, said second section comprising:

- a release channel adapted to allow said retaining means to be released from said track; wherein said second section being adapted to be mounted onto a drillstring or the like and being releasably insertable inside said cavity of said first section through the insertion of said retaining means inside said track.

2. The running-retrieving tool according to claim 1, wherein the retaining means comprise a plurality of J-pins extending radially inwardly from said first section and adapted to fit within said track located on said second section.

3. The running-retrieving tool according to claim 1 or 2, wherein said track comprises an upper lifting shoulder and a lower shoulder portion and a channel located therebetween, wherein said upper lifting shoulder and lower shoulder portion can be separated from one another upon exertion of pressure onto the lower shoulder portion by said retaining means.

4. The running -retrieving tool according to claim 3, wherein said lower shoulder portion of the track comprises a plurality of channel entry points adapted to direct a corresponding plurality of retaining means into the track.

5. The running-retrieving tool according to claim 3, wherein plurality of channels are funnel-like entry points.

6. The running-retrieving tool according to claim 1, wherein the upper lifting section of the track comprises: - a plurality of angled wall sections, each angled wall section comprising a lower end and an upper end and;

7. The running-retrieving tool according to any one of claims 1 to 6, wherein, during operation, upon exertion of a sufficient pressure on the lower shoulder portion of said track, the lower shoulder portion will separate by moving longitudinally away from said upper lifting shoulder thereby creating a plurality of release channels (exit points) associated with corresponding retaining means to release said second section from said first section and leave the first section at a pre-determined location within the wellbore.

8. The running-retrieving tool according to any one of claims 1 to 7, where said lower shoulder portion and said upper lifting portion comprise, at their meeting edge, a complimentary nesting profile adapted to maintain said lower should portion and upper lifting portion in place during rotational movement of a drillstring.

9. The running-retrieving tool according to claim 8 where said complimentary nesting profile comprises a crenellated pattern.

10. The running-retrieving tool according to any one of claims 1 to 9, where said lower shoulder portion has a plurality of projections which combine with a plurality of complimentary projections located on a lower portion of the lifting shoulder of the track to form said plurality of funnel-like entry points.

11. The running-retrieving tool according to any one of claims 1 to 10, where said entry channel comprises a first side member located on a first side of said channel and a second side member located on a second side of said channel, wherein each of member being angled towards a track entry point.

12. The running-retrieving tool according to any one of claims 1 to 11, where said first side member being stationary and wherein said second side member being comprised of: an upper part which is stationary and a lower part which is movable.

13. The running -retrieving tool according to any one of claims 1 to 12, where said upper part of said second side member being located on said upper lifting shoulder of said track and said lower part of said second side member being located on said lower shoulder portion of said track.

14. The running-retrieving tool according to any one of claims 1 to 13, where said nesting gap is a semi-circular opening adapted to secure in place the bearing assembly to the running -retrieval tool.

15. The running-retrieving tool according to any one of claims 1 to 14, where said retaining means nesting gap is offset from said entry channel

16. The running-retrieving tool according to any one of claims 1 to 15, where said nesting gap comprises, on a first adjacent side, an angled wall to allow the upward movement of said retaining means to be directed the channel towards said nesting gap.

17. The running-retrieving tool according to any one of claims 1 to 16, where said nesting gap comprises, on a second adjacent side a wall parallel to a longitudinal axis of said drillstring.

18. A running-retrieving tool for use in oilfield operations, said tool comprising: a first section comprising a bonnet and a split retainer, said first section comprising a cavity having an inner diameter adapted to allow the insertion therethrough of a second section and wherein said first section is adapted to be secured to a tool (such as a bearing assembly); and said second section having an elongated body having an external diameter smaller than the internal diameter of said first section, wherein said first and said second section are releasably secured together in operation by a plurality of concentrically directed J-pins located on said first section engaging with a track located on said second section.