slickline overshot free sample

The Hunting Releasable Overshot is designed to engage tools that have damaged or have no fish necks. The Overshot is designed to withstand high impacts associated with fishing operations.

Hunting Releasable Overshots are available in all common industry toolstring sizes and are manufactured with either sucker rod or integral quick connections as per customer requirements

One option is a side-door overshot as shown in Figure 1. This method is similar to a regular overshot, except that it features a removable side door, so that the tool can be put together around the wireline at the well head itself. It is then possible to run the tool on some tubing or on the drillpipe, downhole alongside the wireline in order to make direct contact with the tool. This stops the wireline from being at risk of parting.

It is not recommended that side-door overshots are used with deep open hole intervals. This is because it introduces the potential for keyseating, or differential sticking in the mud cake.

Throughout modern drilling, the most successful method to retrieve stuck logging tools is through the cut-and-thread method. This involves cutting the wireline at the surface, and then threading it through a pipe string while the pipe is lowered, until it engages with the logging tool. The line must be secured at the surface, and rope sockets need to be fitted to each end to form a spearhead both emerging from the top of the well, and a spearhead overshot at the logging end. A stand of pipe will then be hung in the derrick, allowing enough of an overshot at the bottom to catch the logging tool, or at least the wireline rope socket. When the upper end of the line is spooled down through the interior of the pipe until the overshot connects with the spearhead at the bottom, then the pipe will be run into the hole. This is repeated with additional stands until the bottom of the string is close enough to the fish. When this is achieved, the spearhead overshot can be disengaged and the overshot can be circulated clean, before it engages with the tool. When the fish has been grasped securely, the wireline will be pulled free from the rope socket, and then spooled out of the hole, and the tool itself recovered with the fishing string. Although the cut-and-thread method takes a lot of time, and comes with a certain amount of risk, it vastly improves the chances of recovering the wireline and tool fully, and is much quicker than trying to engage with the wireline in an open hole.

If it is not possible to use either a side-door overshot or a cut-and-thread, then an alternative is to break the weakpoint, and then recover the cable and use the drill pipe to fish for the logging tool. If tool recovery is not an option, then a last resort is to push it to the very bottom of the hole, and then plug it using cement.

[0001] The invention relates generally to a wireline overshot for connecting a wireline to an article within a borehole (or within a downhole tool in the borehole) and/or for retrieving an article from a borehole (or from a downhole tool disposed in the borehole).

[0002] A "wireline" overshot is used to connect a wireline to an article within a drill string. The article can be, but need not be limited to, a wireline coring inner barrel, a soft material sampling tool, a data gathering assembly, or an optional portion of a downhole drilling assembly. The wireline overshot may also be referred to as a fishing tool. In one example, the wireline overshot connects to the article within the drill string by latching over a spearhead coupled to the article. In another example, the wireline overshot may latch onto the article within the drill string by engaging a circular (or receiving) portion of the article. The wireline is commonly a flexible wire rope but may also be a solid wire (or "slickline"), synthetic braided rope, or small-diameter, flexible tubing. The wireline is typically lowered and raised by a winch.

[0003] In a typical core barrel retrieval operation, a wireline overshot is lowered on the end of a wireline down the drill string, where it latches onto an inner tube assembly of a core barrel disposed within the drill string. The wireline overshot is then pulled back to the surface with the attached inner tube assembly. At the drill floor, the inner tube assembly is held in a clamp or lowered onto the drill floor. An operator releases the wireline overshot from the inner tube assembly manually and sets the wireline overshot aside. In cases where the wireline overshot needs to be unlatched from the inner tube assembly while still within the drill string, the method of unlatching the wireline overshot is commonly one of free-falling a release sleeve onto the wireline

overshot, tensioning and releasing the wireline to ratchet a release pall, and repeated pulling or releasing of the wireline to shear a release pin. All of these operations require the wireline overshot to be reconfigured or rebuilt at the surface before it can function as an overshot again.

[0004] In a first aspect of the invention, an overshot comprises a sleeve, a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve, and a load-responsive toggle mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve.

[0005] In a second aspect of the invention, an overshot comprises an outer sleeve and a coupling member disposed a first end of the outer sleeve. A first rotator is disposed within the outer sleeve and configured to alternately engage and disengage from the coupling member, thereby toggling the coupling member between an unlatched state and a latched state. A second rotator is disposed within the outer sleeve and configured to selectively displace and rotate the first rotator in response to an applied load. A weight member is disposed at a second end of the outer sleeve for applying a load to the second rotator.

[0006] In a third aspect of the invention, a method of connecting or disconnecting a wireline from an article comprises providing an overshot comprising a sleeve, a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve, and a load-responsive mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve. The method includes coupling a wireline to the load-responsive mechanism, aligning the article with the coupling member, and selectively activating the load- responsive mechanism to alternate the coupling member between the latched state where it engages the article and the unlatched state where it disengages from the article.

[0012] FIG. 4 shows a weight jar assembly of the overshot of FIG. 1 applying a load to an upper rotator of the overshot of FIG. 1 while the overshot is in an unlatched state.

[0016] FIG. 8 shows a weight jar assembly of the overshot of FIG. 1 applying a load to an upper rotator of the overshot of FIG. 1 while the overshot is in the latched state.

[0017] FIG. 9 shows the keys of the lower rotator of the overshot of FIG. 1 released from the key slots of the key holder sleeve of the overshot of FIG. 1.

[0019] FIG. 11 shows the overshot of FIG. 1 after it has engaged an inner tube assembly within a drill string and has been retrieved to the surface with the inner tube assembly.

[0020] FIG. 1 is a cross-section of an overshot 10 for connecting a wireline to an article. The overshot 10 includes a cap 60 for connection to a wireline. A weight jar assembly 44 is coupled to the cap 60. The weight jar assembly 44 may include a weight bar 19 attached to the cap 60 by fasteners 21 , e.g., thread-and-set screws, and a jar stem 23 attached to the weight bar 19 by fasteners 25, e.g., thread-and-set screws. The jar stem 23 is received in a sleeve 22 and retained in the sleeve 22 by a jar bushing 27 mounted at the upper end of the sleeve 22. A toggle head 13 is received in the sleeve 22 and is positioned below the jar stem 23. A coupling member 14 is coupled to the toggle head 13 for engaging an article of interest. The article of interest may be any tool requiring a releasable connection with a wireline. For example, the article may be an inner tube assembly used to collect core samples from a subsurface formation, a soft material sampling tool, a data gathering assembly, and a component of a downhole drilling assembly. Connection and release of the overshot 10 from the article can be made at the surface, within a borehole, or within a tool disposed in the borehole.

[0022] Returning to FIG. 1 , the lifting dogs 18 are pivotally coupled to an axle 26 of the toggle head 13. A spring 28 is disposed between the upper ends 30 of the lifting dogs 18 to bias the upper ends 30 of the lifting dogs 18 away from each other. The pivot joint 33 between the lifting dogs 18 causes the lower ends 32 of the lifting dogs 18 (which include the hooks for engaging a part) to be biased in a reverse direction to the upper ends 30 of the lifting dogs 18. A toggle mechanism for moving the lifting dogs 18 between the latched and unlatched states includes a lower rotator 34. In the unlatched state, the upper ends 30 of the lifting dogs 18 are received within a bore of the lower rotator 34 so that the wall of the lower rotator 34 acts as a restraining ring around the upper ends 30 of the lifting dogs 18. In this unlatched state, the upper ends 30 of the lifting dogs 18 are forced towards each other against the force of the spring 28 and the lower ends 32 of the lifting dogs 18 are forced away from each other. The lower rotator 34 is axially movable along the toggle head 13 and sleeve 22. To transition the overshot 10 to a latched state, the lower rotator 34 is moved a sufficient distance in an upward direction to release the upper ends 30 of the lifting dogs 18 from the lower rotator 34. Once the upper ends 30 are released, the spring 28 would move the upper

[0023] The toggle mechanism includes an upper rotator 40 disposed about the shaft 24. The upper rotator 40 is held in place above the lower rotator 34 (and about the shaft 24) by a spring 42. The term "rotator," as used herein and above, means a part that can rotate or that can rotate another part. In one example, the upper rotator 40 is configured to rotate the lower rotator 34. The upper rotator 40 is slidable along the shaft 24 upon application of a load to the upper rotator 40 by the weight jar assembly 44. For the upper rotator 40 to be slidable, the load applied by the weight jar assembly 44 must be sufficient to overcome the biasing force of the spring 42 holding the upper rotator 40 in place. As will be further explained below, the load should also be sufficient to overcome the biasing force of the spring 38 holding up the lower rotator 34, or the biasing force of the spring 38 holding up the lower rotator 34 should be less than that of the spring 42 holding up the upper rotator 40. A wireline (not shown) coupled to the weight bar 19 through the cap 60 is used to control the position of the jar stem 23 (of the weight jar assembly 44) within the sleeve 22. The jar stem 23 is movable between an upper position limited by the jar bushing 27 (at the upper end of the sleeve 22) and a lower position limited by the upper rotator 40. When the weight jar assembly 44 rests on the upper rotator 40, it applies a load to the upper rotator 40. As will be explained below, this load assists in shifting the lifting dogs 18 between the latched and unlatched states. Contact is required between the jar stem 23 and the upper rotator 40 to allow the weight jar assembly 44 to apply a load to the upper rotator 40. Contact can be achieved in one of two ways. One way is by letting go of tension in the wireline (not shown) coupled to the weight bar 19 so that the jar stem 23 slides down the shaft 24 to contact the upper rotator 40. The other way is by moving the overshot 10 upwardly so that the upper rotator 40 slides up the shaft 24 to contact the jar stem 23. A jar bushing

12 latched into a core barrel 56. The overshot 10 is in an unlatched state, with the lifting dogs 18 slid down the spearhead 16 and held open by the shoulder 57 of the spearhead 16. This frees the lower rotator 34 to rotate without the friction that would be caused by the spring 38. In the example shown in FIG. 3, tension in the wireline has been relaxed, allowing the weight jar assembly 44 to rest on and apply a load to the upper rotator 40. Relative motion between the overshot 10 and the wireline (not shown) is used to bring the jar stem 23 of the weight jar assembly 44 in contact with the upper rotator 40. Relative motion can be achieved by releasing the weight jar assembly 44 from above,

e.g., through relaxation of tension in the wireline coupled to the weight jar assembly 44, or by moving the overshot 10 upwardly. The weight jar assembly 44 applies weight to the upper rotator 40 and, as shown in FIG. 4, causes the upper rotator 40 to slide down the key holder sleeve 46 and engage the lower rotator 34. As shown in FIG. 5, the upper rotator 40 pushes the lower rotator 34 down until the keys 54 (on the lower rotator 34) are positioned below the keys 48 (on the key holder sleeve 46). As previously explained, the load applied by the weight jar assembly (44 in FIG. 1 ) must be sufficient to overcome the force of the spring (42 in FIG. 1 ) holding up the upper rotator 40 and the force of the spring (38 in FIG. 1 ) holding up the lower rotator 34. The lower rotator 34 then rotates clockwise (looking down) as the tension of the spring (38 in FIG. 1 ) pushes the lower rotator 34 upwardly against the beveled surface 62 of the upper rotator 40. The keys 54 slide into the key slots 50 without the stop pins 52, as shown in FIG. 6. The lower rotator 34 moves upwardly as the keys 54 slide upwardly inside the key slots 50. As shown in FIG. 7, this causes the upper ends 30 of the lifting dogs 18 to be released from the lower rotator 34. The spring 28 moves the upper ends 30 of the lifting dogs 18 outwardly, which causes the lower ends 32 of the lifting dogs 18 to move inwardly and latch onto the spearhead 16. In the latched state, the weight jar assembly 44 is held again in tension to avoid exerting weight on the upper rotator 40, and the upper rotator 40 is held above the lower rotator 34 by the spring 42. The lower rotator 34 is held in place by the keyed connection described above and the force of the spring 38.

[0026] To release the lifting dogs 18 from the spearhead 16, the weight jar assembly 44 is again brought into contact with the upper rotator 40 to apply a load to the upper rotator 40, as shown in FIG. 8. As previously explained, the weight jar assembly 44 can either slide down to contact the upper rotator 40, or the overshot 10 can be moved upwardly to allow the upper rotator 40 to slide up and contact the weight jar assembly 44. The upper rotator 40, under the load of the weight jar assembly 44, slides down the key holder sleeve 46 to engage the lower rotator 38 and push the lower rotator 38 down so that, as shown in FIG. 9, the keys 54 are positioned below the keys 48. For this to happen, the load applied by the weight jar assembly 44 must be

[0027] The overshot 10 can be used to connect a wireline to an article, such as an oilfield tool, either at the surface or in a borehole. The overshot 10 can be disconnected from the article by the same action used in connecting the overshot 10 to the article, as described above. The overshot 10 can be used in any drilling or wireline operation. For illustration purposes, FIG. 10 shows the overshot 10 suspended at the end of a wireline 70 in preparation for lowering the overshot 10 into a drill string 72 containing a core barrel with an inner tube assembly. The drill string 72 is disposed in a borehole 73 drilled in a subsurface formation 75. FIG. 11 shows the overshot 10 after it has engaged the inner tube assembly 12 and been retrieved to the surface with the inner tube assembly 12. A handling arm 74 holds the inner tube assembly 12 while the overshot 10 is disengaged from the inner tube assembly 12 as described above.

The Series 10 Sucker Rod Overshot is a small, rugged tool designed for engaging and retrieving sucker rods, couplings, and other items from inside tubing strings.

Series 20 Short Catch Sucker Rod Overshots are designed for conditions when sucker rods, couplings, and other portions of a fish are too short for retrieval with a standard overshot.

The Hydraulic Release Overshot was designed to aid in the recovery of a stuck fish in a horizontal drilling application where normal rotation for release is not obtainable.

The Series 150 Releasing and Circulating Overshot consists of three main external parts: a Top Sub, a Bowl, and a Guide. Internal catch and pack-off parts are determined by the diameter of the fish. Each assembly is designed for a maximum catch diameter.

A Series 160 Side Door Overshot is recommended when fishing for cable tools or conductor lines in cased holes. The side door overshot is run in on tubing or drill pipe.

An example of a fishing operation is the retrieval of a logging tool string that is stuck in a well. Logging tools may become stuck due to encounters with bridges, cave-ins, swelling formations, debris and the like. Often, an overshot device is used to enage the stuck tool string. During fishing operations, it is common practice to circulate mud or other substances down onto the stuck tools to clean the top of the fish that protrudes from the cable head of the tool string, and to determine when the overshot assembly engages the tool string. Typically, when the pump pressure increases, it is assumed that the pressure increase is due to the logging string being swallowed up by the fishing equipment overshot device. Currently, reconnecting the wireline during the fishing operation allows the logging engineer to monitor the down hole tension in order to determine when the drill string is pushing against the tool string and limit the weight that the driller puts down upon the tool string. In this way, the operator can recover the tool in a working condition and continue with the logging operation. It is important that the logging operation continue because the logging operation cost is based largely on the rig operation which is charged on an hourly basis and is generally quite expensive. Recovery of the tool reduces but does not eliminate the possibility that the tool string is dropped when the drill pipe is retrieved to the surface. The problem with the current state of affairs is that the tension increase that is seen by the logging engineer is only an indication that the drill string is pushing on the tool string. The tension increase is not, however, a complete indication that the overshot has actually swallowed the instrument itself or that the tool string is being engaged by the grapple within the overshot device. Instead, the tension increase could be the result of debris or other matter within the borehole itself that is preventing the instrument from being completely grappled by the overshot device.

If the tool string is not properly engaged by the grapple, the tool string may be dropped while the drill pipe is being retrieved to the surface. Unfortunately, dropping the tool string is a familiar occurrence during fishing operations. The weight of the logging tool string is light by comparison to the drill string, and therefore the driller often does not sense the weight of the logging tool string on his weight indicator because it is so small in comparison to the rest of the equipment. Moreover, once the tool string is engaged, circulation is generally impossible or only possible when a pump out sub is run for the express purpose of providing circulation after the fish is engaged. In many cases it is not recommended to circulate because the possibility exists that the fishing neck of the tool string is not properly engaged and the circulation can push the tool string out of the fishing equipment and be lost once again downhole. There is, therefore, a need in the art for some mechanism to ensure proper engagement with the tool string with the overshot device.

The present disclosure illustrates how shortcomings of the prior art may be overcome by providing an engagement sensor or a mechanical device that can be placed in the cable head of a logging tool string and/or the fishing equipment to allow the logging engineer and/or the pump operator to monitor the fishing operation. The mechanical devices or sensors can be used as an indicator that the overshot device has indeed swallowed the tool string, and/or that the grapple is properly engaging the tool string. The sensor disclosed herein can be positioned and/or designed to allow the engineer or the driller to monitor the fishing grapple, the swallowing of the tool string at one or more points during the swallowing process. In other words, the sensors and mechanical devices disclosed herein can be enhanced further to measure the amount of the tool string that the overshot device may be actually swallowing at one or more points of the swallowing process.

The sensor disclosed herein can be a mechanical switch in the tool string that may be connected to a resistor or to a variable resistor to indicate the portion of tool string that may be being swallowed by the overshot device. In an alternate embodiment, the sensor could be a Hall effect sensor in the logging tool that indicates the increased presence of metal around the tool string body. In yet another alternate embodiment of the present disclosure, a mechanical setup may be designed such that when the overshot device swallows the tool string to the proper point, a switch or other mechanical device that may be fixed in the fishing equipment opens a circulation port that will cause the mud pumps to pulse or to exhibit some other significant fluctuation in pressure that may be detectable by the operator which will provide a positive indication to the operator that he has properly engaged the tool string. In yet another embodiment, an enhancement can be made to a hydro timer that, after a given time frame, would turn off the pulsing or other significant change mentioned previously, which can be interpreted as a further indication (or lack thereof) that the desired action has transpired.

If the sensor in the tool string may be connected to a resistor or to a variable resistor, then the conductor within the wireline that the resistor may be in line with can be monitored with a meter on the surface so that the monitoring may be both safe and easy. Such an embodiment would be preferable to monitoring with a computer, either downhole or remotely, such as during the retrieval of a non-detonated perforating device. Such an embodiment would also provide the ability to monitor the operation on the rig floor without reconnecting the wireline. Finally, if a mechanical device is placed in the fishing equipment (such as the overshot device), the mechanical device can be used to fish for the tool string in situations where the wireline has been removed in order to speed the fishing operation, such as in Cased Hole operations.

Other advantages of the method, system and apparatus disclosed herein include two or more or a combination of the following: (1) an increased level of safety; (2) for situations where the tool may be reconnected electrically, there will be the ability to monitor the downhole tension reading if the tension capability may be included in the logging tool string; (3) sensor data or a positive indication of engagement may be provided in real time; (4) positive indication of engagement of the logging tool string may be transmitted to and/or monitorable on the surface, thereby eliminating guesswork as to whether or not the overshot device may be swallowing the logging tool string rather than simply pushing on the sides or the top of the tools; (5) there may be a decreased possibility of dropping the tool string while retrieving the drill pipe to the surface; (6) no tension increase or decrease may be required to engage the tool string as there may be a positive indication that the overshot device and the tool string are engaged—which will decrease the possibility of accidentally breaking the weak point in the string; (7) the decreased tension that may be required to engage the tool string made possible with the system disclosed herein will also reduce the damage to the logging tools that are incurred during the fishing operation, thereby prolonging tool life; (8) apparatus disclosed herein will also allow fishing equipment to be designed for better circulation capabilities, before and after engagement as the pressure increase and circulation loss will no longer be required to confirm that the overshot has properly swallowed the tool string; therefore, the circulation can be used for other purposes such as evacuation from the hole and other applications. The apparatus disclosed herein is in stark contrast to the current state of the art where circulation is limited after the overshot has swallowed the tool unless a pump out sub is incorporated into the fishing equipment. Embodiments disclosed herein obviate the need for the pump out sub.

The instrument 206 typically (although not always) has the largest outside diameter (“o.d.”) of any of the segments. The o.d. of the tool string 200 may be the defining factor in selecting the inside diameter (“i.d”) of the overshot device 300, because in many cases, it can be desirable for at least part of the tool string 200 to fit within the overshot device 300, and thus the i.d. of the overshot device 300 should be large enough to accommodate the o.d. of the portion of the tool string 200 that is expected to be swallowed by the overshot device 300. If it is desirable for the overshot device 300 to swallow part of the tool string 200, then the length of the overshot device 300 should be long enough to accommodate the length of the tool string 200 to be swallowed. The i.d. of the borehole 160 may limit the o.d. of the overshot device 300, which may limit the part of the tool string 200 that can be swallowed by the overshot device 300 up to the cable head 204 or up to the fishing neck 202.

An overshot device can be illustrated in FIG. 3. The overshot device 300 can contain one or more parts, as illustrated in FIG. 3. In this illustrative example, the overshot device 300 can be composed of a top sub 302, a bushing 304, a bowl 306 that has a distal end 305 that can be threadably engaged with the top sub 302, although other types of engagement is besides threading is possible. Within the postal end 307 of the bowl 306 are placed a packer seat ring 308, a grapple 310 (used to retain the tool string 200), a grapple control 312 (used to activate or deactivate the grapple 310), and a guide 314. In operation, the bottomhole assembly (FIG. 1) can be removed and may be replaced by the overshot device 300. The overshot device 300 can be oriented so that the guide 314 can be used to guide the fishing neck 202 into the overshot device 300 during the fishing operation. In many cases, the overshot device 300 can be hollow to allow the cable 201 to run contiguously from the tool string 200 to the surface 101. Moreover, the overshot device 300 has a hollow section at one end (in proximity to the grapple 310) to accommodate the tool string 200.

FIG. 4 illustrates an embodiment of the present disclosure. This embodiment of the tool string 200 includes a sensor 402. The sensor 402 can be a mechanical switch that engages an internal shoulder of the overshot device 300 when the tool string 200 can be swallowed to the desired amount. When the sensor 402 is depressed (by the shoulder within the overshot device 300), a signal can be passed up through the wire cable 201 to the operator on the surface to inform him that the tool string 200 is properly engaged within the overshot device 300.

FIG. 5 illustrates an embodiment of the present disclosure. The embodiment of FIG. 5 has the sensor 502 on the fishing neck 202. The sensor 502 in this embodiment can be a Hall effect sensor that indicates the presence of metal around the tool string 200. The sensor 502 has the advantage of being able to be placed flush with the local surface of the local tool string 200 so that debris (or another part of the overshot device 300) do not prematurely trip the sensor 502 as may happen with the sensor 402. Moreover, the sensor 502, because it can be flush-mounted, may be placed anywhere along the tool string 200. For example, the sensor 502 acan be placed within of the tool string 200, and would only be triggered (provide a positive indication) if the tool string 200 were swallowed to a particular point by the overshot device 300. Similarly, multiple sensors 502 could be mounted onto the tool string 200 along the fishing neck 202, the shoulder 203, the cable head 204 and the instrument 206 to provide a better indication to the operator of the progress of the fishing operation (as sequential sensors would provide positive indications as the overshot device 300 swallows the tool string 200. As with the previous embodiment, the sensors 502 can send their positive (or negative) indicator signals through the cable 201 to, for example, the computer 190 for processing and display to the operator.

FIG. 6 illustrates an embodiment where a valve 602 can be placed on the overshot device 300. The valve 602 allows the circulation (of mud, etc.) from the overshot device 300 to the downhole environment. Moreover, the valve 602 can be positioned in proximity to the shoulder 604 of the overshot device 300. When the tool string 200 is brought up into the overshot device 300, the fishing neck can be pulled through the orifice 606 of the shoulder 604 until the shoulder 203 of the tool string 200 engages the shoulder 604 of the overshot device 300. A mechanical setup on the overshot device 300 and/or the tool string 200 can be provided to activate when the overshot device 300 swallows the tool string 200 to the proper point (such as when the shoulders 203 and 604 engage). Upon activation, a switch or other mechanical device that can be fixed in the fishing equipment opens a circulation port 602 that will cause the mud pumps (not shown) to pulse or to exhibit some other significant fluctuation in pressure that can be detectable by the operator. Depending upon how the circulation pulse is arranged, the valve 602 may be opened (to relieve the pressure of the circulation pulse that can no longer exit because of the presence of the tool string 200), or closed (because the circulation pulse can no longer exit the overshot device 300 via the orifice 606). The open or closed position of the valve 602 can be detected and an appropriate signal sent toward the surface 101 for processing and/or display to the operator. The pulse or fluctuation in pressure can provide a positive indication to the operator that he has properly engaged the tool string 200.

FIG. 7 illustrates an embodiment of the overshot device 300 that can be fitted with a circulation port 702. The circulation port 702 can, in one embodiment, be fitted with a membrane. The membrane acts as a safety valve. When the tool string 200 is swallowed by the overshot device 300 (to the point where the shoulders 203 and 604 engage), then the circulation fluid driven through the overshot device 300 can be trapped, with a corresponding pressure increase within the overshot device 300. The pressure increase may be detectable by instruments within the overshot device 300. Moreover, the membrane of the circulation port 702 can be constructed and arranged to burst at a predesignated pressure that may also be detected by instruments within the overshot device 300. Appropriate signals corresponding to the pressure measurements may be sent to the surface 101 for processing and/or display to the operator.

FIG. 9 illustrates an embodiment where there are multiple sensors 902 positioned along the overshot device 300. In this embodiment, as the tool string 200 can be swallowed by the overshot device 300, the sensors 902 detect the presence of the tool string 200 (by, for example, magnetically, or by the Hall effect, or some similar manner) at various locations during the swallowing procedure. As the tool string 200 can be successively swallowed by the overshot tool 300, the signals from each individual sensor 902 will sequentially provide a positive indication of the progression of the tool string 200 into the overshot device 300. The advantage of this embodiment is that the swallowing procedure can be monitored more closely by the operator as the sensors 902 send successive positive signals to the surface 101. Thus the operator can have a better indication of just how close the shoulder 203 of the tool string 200 can be to mating with the shoulder 604 of the overshot device 300.

FIG. 10 illustrates the method 1000 of using the apparatus described above. The method begins generally at step 1002. If the overshot device 300 is not already in place, the bottom hole assembly can be replaced with the overshot device 300 in step 1004. The overshot device 300 can then be placed downhole, in step 1006, in proximity to the location of the lost or stuck tool string 200. Once the overshot device 300 is in position, in step 1008, the overshot device 300 can begin swallowing the tool string 200. In step 1010, the overshot device 300 swallows the tool string 200. In one embodiment disclosed of step 1010, herein, the sensor or mechanical device that indicates positive engagement will activate only when the tool string 200 is engaged the overshot device 300 at the final position (i.e., ready to pull up to the surface 101). In other embodiments of step 1010, multiple sensors or mechanical devices on the tool string 200 and/or the overshot device 300 activate at successive (perhaps even or uneven) intervals to indicate the position of the tool string 200 within the overshot device 300 at various points along the swallowing process and the method ends generally at step 1012. The latter embodiment provides the operator with a better indication of the progress of the method disclosed herein.

FIG. 11 illustrates an alternate method 1100 of using the apparatus described above. The method begins generally at step 1102. If the overshot device 300 is not already in place, the bottom hole assembly can be replaced with the overshot device 300 in step 1104. The overshot device 300 can then be placed downhole, in step 1106, in proximity to the location of the lost or stuck tool string 200. Once the overshot device 300 is in position, in step 1108, the overshot device 300 can begin swallowing the tool string 200. In step 1110, a decision is made whether to reconnect the wireline. If the wireline is to be reconnected (e.g., the answer to step 1110 is “yes”), then the tool string 200 can be reconnected to the wireline in step 1112. In either case, in one embodiment of step 1114, the sensor or mechanical device that indicates positive engagement will activate only when the tool string 200 is engaged the overshot device 300 at the final position (i.e., ready to pull up to the surface 101), an activity which may be monitored by human and/or electromechanical means. In other embodiments of step 1114, multiple sensors or mechanical devices on the tool string 200 and/or the overshot device 300 activate at successive (perhaps even or uneven) intervals to indicate the position of the tool string 200 within the overshot device 300 at various points along the swallowing process and the method ends generally at step 1116. The latter embodiment provides the operator with a better indication of the progress of the method disclosed herein.

6. Lower the drillstring and lartch onto the fish. Do not locate or engage the logging tool with more than 20 000 lbs or the weight advised by the Logging Contractor. A pressure increase shall indicate if the fish is caught in the overshot. A cable head tension increase when lowering the drillstring, or a decrease when pulling the drillstring indicates that the fish is connected.

7. Observe the cable tension. If the tension drops, there is a good chance that the fish has been latched on. Repeat this procedure a few times to make sure this is the case. If there is no drop in tension, Go down with the overshot a little deeper than before and repeat the procedure.

The introduction will provide a brief overview of EMEPMI wells, typical conventional workover rig (CWR) and non-rig wellwork operations such as coiled tubing operations, well servicing and wireline/slickline work. Subsequently, case examples will describe the planning and execution of non-routine non-rig wellwork operations, namely:–