阅读说明：本技术 一种井下落物打捞器 (Fishing tool for underground falling objects ) 是由 杨一迪 刘云云 刘浩 熊坤 杨易骏 陈旭 朱梦迪 陶涛 李雪晴 赵建军 张家伟 于 2019-10-23 设计创作，主要内容包括：本发明提供了一种井下落物打捞器,包括：筒体；上接头,连接在筒体上部；卡瓦,设在筒体内,卡瓦内壁上设有卡牙；压板,设在筒体内且位于卡瓦上方；螺旋弹簧,设在上接头和压板之间；压板上设有导杆,螺旋弹簧套在导杆外,导杆上端向上穿入上接头中,上接头内设有导杆穿孔,上接头上还设有供拆卸杆从径向插入的插孔,插孔与导杆穿孔连通,导杆上设有与拆卸杆配合的配合结构。有益效果：拆卸杆向上提拉时,导杆带着压板向上移动,解除对卡瓦的压紧,使卡瓦向上复位并张开,与落物上的打捞头分离,本发明避免了在筒体上设置滑槽,保证筒体的结构强度不受影响；拆卸杆未连接在打捞器上,不会增加打捞器的横向尺寸,保证打捞器的适应能力也不受影响。(The invention provides a fisher for underground junk, which comprises: a barrel; the upper joint is connected to the upper part of the cylinder body; the slips are arranged in the cylinder body, and the inner wall of the slips is provided with clamping teeth; the pressing plate is arranged in the cylinder body and is positioned above the slips; the spiral spring is arranged between the upper joint and the pressure plate; the pressure plate is provided with a guide rod, the spiral spring is sleeved outside the guide rod, the upper end of the guide rod upwards penetrates into the upper joint, a guide rod through hole is formed in the upper joint, the upper joint is further provided with a jack for the dismounting rod to be inserted from the radial direction, the jack is communicated with the guide rod through hole, and the guide rod is provided with a matching structure matched with the dismounting rod. Has the advantages that: when the dismounting rod is pulled upwards, the guide rod drives the pressing plate to move upwards, the pressing on the slips is released, and the slips are reset upwards and opened to be separated from the fishing head on the falling object; the dismounting rod is not connected to the fisher, so that the transverse size of the fisher cannot be increased, and the adaptability of the fisher is not affected.)

1. A downhole junk overshot, comprising:

the axis of the cylinder extends along the up-down direction, and the lower end surface of the cylinder is a conical guide surface which gradually inclines inwards from bottom to top so as to guide the fishing head on the falling object to enter the cylinder;

the upper joint is connected to the upper part of the barrel body, and a connecting structure used for being connected with the fishing pipe column is arranged on the upper joint;

the slip is provided with at least two sections and is arranged in the cylinder body, the inner wall of the slip is provided with a clamping tooth for clamping the fishing head, and the outer side wall of the bottom of the slip is mutually matched with the inner wall of the bottom of the cylinder body through a conical surface which gradually inclines inwards from top to bottom;

the pressing plate is arranged in the cylinder body, is positioned above the slips and is used for pressing the slips downwards;

the spiral spring is arranged between the upper joint and the pressure plate and used for providing downward elastic acting force for the pressure plate after being compressed;

the method is characterized in that:

the upper end face of the pressing plate is provided with a guide rod extending upwards, the spiral spring is sleeved outside the guide rod, the upper end of the guide rod penetrates upwards into the upper connector, a guide rod perforation is arranged in the upper connector, an insertion hole which is used for inserting an external dismounting rod from the radial direction and can move up and down relative to the upper connector after being inserted is further arranged on the upper connector, the insertion hole is communicated with the guide rod perforation to enable the dismounting rod to be inserted into the guide rod perforation, and a matching structure which is used for being matched with the dismounting rod and moving upwards under the upward lifting action force of the dismounting rod is arranged on the guide rod and corresponds to the insertion hole.

2. A downhole junk overshot according to claim 1, wherein: the jack has two, and two jacks are located same footpath.

3. A downhole junk overshot according to claim 2, wherein: the upper joint is in threaded connection with the barrel, a hexagonal prism structure facilitating screwing of the upper joint is arranged on the upper joint, and the two jacks are respectively arranged on two opposite side faces of the hexagonal prism structure.

4. The fishing tool for the fallen objects in the well according to any one of claims 1 to 3, wherein: the guide rod comprises a guide rod body, a connecting rod and a top plate, wherein the connecting rod is fixed at the upper end of the guide rod body, the diameter of the connecting rod is smaller than that of the guide rod body, the top plate is fixed at the upper end of the connecting rod, and the matching structure is formed by the bottom surface of the top plate.

5. The fishing tool for the fallen objects in the well according to any one of claims 1 to 3, wherein: the bottom of the pressure plate is provided with a contact body which is in contact with the inner wall of the slip top part to guide the deformation of the slip.

Technical Field

The invention relates to a fisher for underground junk.

Background

At present, when pressure tests are carried out on domestic oil and gas wells and corrosion hanging pieces in the wells are monitored, the well hanger is commonly used, the fishing head on the upper portion of the well hanger is mainly of a cone (shown in figure 1), a hemisphere (shown in figure 2) and a cylinder (shown in figure 3) type structure, the fishing head is provided with a step surface which is a cone step surface 1, a hemisphere step surface 2 and a cylinder step surface 3 respectively, and therefore a special fishing device is needed to hook the step surfaces to fish the well. In addition, objects such as broken sucker rods and oil pump cores frequently fall to the bottom of the well in the process of oil field operation to cause underground accidents, and in order to avoid influencing the oil production, the objects need to be salvaged by utilizing a salvage device.

The utility model discloses a chinese utility model patent that the bulletin number is CN201428409Y discloses a quick detach fisher, including barrel and threaded connection compressing tightly on barrel upper portion connect, be connected with the card tile through articulating the slider in the barrel, articulate the slider and compress tightly and be provided with compression spring between the joint, articulate the footpath of slider and be equipped with the pinhole, have inserted the slide bar in the pinhole, be provided with the spout on the barrel, the slide bar slides along the spout on the barrel. When the device is used, falling objects are guided to enter the cylinder under the guidance of the bottom of the cylinder and push the slip clamping piece upwards, so that the slip clamping piece moves upwards and opens, the falling objects are clamped after entering the slip clamping piece, and then the pipe column is lifted up to take out the falling objects. When the junk and the fisher need to be separated, the sliding rod of the hanging sliding block is buckled and lifted, and after the spring force is overcome, the fisher is lifted, so that the fisher and the junk can be quickly separated.

Although the quick separation of the junk can be realized to the fisher, the sliding groove needs to be arranged on the barrel body so that the sliding rod can penetrate through the barrel body and be connected with the sliding block in a hanging mode, the structural strength of the barrel body is affected, and particularly, the barrel body is easy to deform as a bearing piece bearing the weight of the junk, so that the service life of the barrel body is affected. In addition, in order to conveniently lift the sliding rod, the end part of the sliding rod needs to extend out of a part of the cylinder body, so that the transverse size of the fisher is increased, the fisher cannot be put into a well with a smaller diameter, and the adaptability of the fisher is reduced.

Disclosure of Invention

The invention aims to provide a downhole junk fisher which can conveniently separate junk from the fisher and does not influence the structural strength of a barrel body and the adaptability of the fisher.

In order to achieve the purpose, the underground junk fisher adopts the following technical scheme:

a downhole junk overshot, comprising:

the axis of the cylinder extends along the up-down direction, and the lower end surface of the cylinder is a conical guide surface which gradually inclines inwards from bottom to top so as to guide the fishing head on the falling object to enter the cylinder;

the upper joint is connected to the upper part of the barrel body, and a connecting structure used for being connected with the fishing pipe column is arranged on the upper joint;

the slip is provided with at least two sections and is arranged in the cylinder body, the inner wall of the slip is provided with a clamping tooth for clamping the fishing head, and the outer side wall of the bottom of the slip is mutually matched with the inner wall of the bottom of the cylinder body through a conical surface which gradually inclines inwards from top to bottom;

the pressing plate is arranged in the cylinder body, is positioned above the slips and is used for pressing the slips downwards;

the spiral spring is arranged between the upper joint and the pressure plate and used for providing downward elastic acting force for the pressure plate after being compressed;

the upper end face of the pressing plate is provided with a guide rod extending upwards, the spiral spring is sleeved outside the guide rod, the upper end of the guide rod penetrates upwards into the upper connector, a guide rod perforation is arranged in the upper connector, an insertion hole which is used for inserting an external dismounting rod from the radial direction and can move up and down relative to the upper connector after being inserted is further arranged on the upper connector, the insertion hole is communicated with the guide rod perforation to enable the dismounting rod to be inserted into the guide rod perforation, and a matching structure which is used for being matched with the dismounting rod and moving upwards under the upward lifting action force of the dismounting rod is arranged on the guide rod and corresponds to the insertion hole.

The technical scheme of the fishing tool for the underground junk has the advantages that: the guide arm on the clamp plate up end upwards penetrates the top connection, and still be provided with on the top connection and supply outside dismounting rod from radial male jack, because jack and the perforation intercommunication of guide arm, consequently the dismounting rod can insert the guide arm through the jack and perforate, and the position corresponding with the jack on the guide arm is equipped with the cooperation structure, this cooperation structure can cooperate with the dismounting rod, upwards remove under the upwards pulling effort of dismounting rod, just so can take clamp plate rebound by the guide arm, thereby upwards compress coil spring, make the clamp plate relieve the compressing tightly of slips simultaneously, make the slips can upwards reset and open along the conical surface of barrel bottom inner wall, thereby with the separation of fishing head on the junk, can realize the separation of fisher and junk.

According to the invention, the guide rod is arranged, the matching structure is arranged on the guide rod, and the jack is arranged on the upper joint, so that a sliding groove is prevented from being arranged on the cylinder body, and the structural strength of the cylinder body can be ensured not to be influenced; and only when need with junk and fisher separation in, just insert jack and guide arm perforation with the stripper bar from the outside to with the cooperation structure cooperation on the guide arm, through upwards lifting pull the stripper bar, make the guide arm rebound thereupon, remove the clamp plate to the compressing tightly effect of slips, that is to say, the stripper bar does not connect on the fisher, just so can not increase the transverse dimension of fisher, has guaranteed that the adaptability of fisher is also not influenced.

Furthermore, in order to facilitate the force application from the two ends of the dismounting rod and further move the guide rod upwards more easily, the number of the jacks is two, and the two jacks are located in the same radial direction.

Furthermore, in order to facilitate connection between the upper joint and the barrel body and assembly of the upper joint and arrangement of the jacks, the upper joint is in threaded connection with the barrel body, a hexagonal prism structure which facilitates screwing of the upper joint is arranged on the upper joint, and the two jacks are respectively arranged on two opposite side faces of the hexagonal prism structure.

Furthermore, in order to facilitate the processing and manufacturing of the guide rod and the arrangement of a matching structure, the guide rod comprises a guide rod body, a connecting rod fixed at the upper end of the guide rod body and a top plate fixed at the upper end of the connecting rod, wherein the diameter of the connecting rod is smaller than that of the guide rod body, and the matching structure is formed by the bottom surface of the top plate.

Further, in order to prevent the top end of the slip from deforming inwards when being pressed, the bottom of the pressure plate is provided with a contact body which is contacted with the inner wall of the top of the slip to guide the deformation of the slip.

Drawings

FIG. 1 is a schematic structural diagram of a cone fishing head in the prior art;

FIG. 2 is a schematic structural view of a hemispherical fishing head in the prior art;

FIG. 3 is a schematic structural view of a cylindrical fishing head in the prior art;

FIG. 4 is a schematic structural view of the down hole junk fisher of the present invention prior to fishing out the down hole junk;

fig. 5 is a schematic structural view of the down-hole junk fisher according to the present invention when it is separated from the stuck down-hole junk.

In the figure: 1. a cone step surface; 2. a hemisphere step surface; 3. a cylindrical step surface; 10. a barrel; 11. an upper conical surface; 12. a tapered guide surface; 20. slips; 30. an upper joint; 31. an upper column; 32. a hexagonal prism; 33. a lower column; 34. a round bar; 35. a frustum; 36. perforating a guide rod; 37. a jack; 40. a coil spring; 50. a guide bar; 51. a guide rod body; 52. a connecting rod; 53. a top plate; 60. pressing a plate; 70. a contact body.

Detailed Description

One embodiment of the present invention is a fishing tool for a junk in a well, which is shown in fig. 4, and includes a barrel 10 having an axis extending in an up-down direction, and having openings at upper and lower ends of the barrel 10. The upper end of the barrel 10 is in threaded connection with an upper joint 30, the upper joint 30 sequentially comprises an upper cylinder 31, a hexagonal cylinder 32, a lower cylinder 33, a round rod 34 and a frustum 35 from top to bottom, wherein the upper cylinder 31 and the lower cylinder 33 are both cylinders, external threads are processed on the outer surfaces of the upper cylinder 31 and the lower cylinder 33, and the upper cylinder 31 is used for being connected with a fishing string on the upper portion, so that a connecting structure for being connected with the fishing string on the upper joint 30 is formed. The lower cylinder 33 extends into the interior of the cylinder 10 and is threadedly coupled with the cylinder 10.

The slip 20 is arranged in the cylinder 10, the inner wall of the slip 20 is provided with a clamping tooth for clamping the fishing head, the slip 20 in the embodiment has three petals, and the petals are arranged separately. The outer side wall of the bottom of the slip 20 is matched with the inner wall of the bottom of the cylinder 10 through conical surfaces which are gradually inclined inwards from top to bottom, namely an upward upper conical surface 11 is arranged at the bottom of the cylinder 10, a downward lower conical surface is arranged at the bottom of the slip 20, and the upper conical surface 11 and the lower conical surface are gradually inclined inwards from top to bottom and have the same taper. In addition, the lower end surface of the cylinder 10 is a tapered guide surface 12 which is gradually inclined inward from bottom to top to guide the fishing head on the hanger into the interior of the cylinder 10.

The cylinder 10 is further provided with a pressing plate 60, and the pressing plate 60 is located above the slips 20 and used for pressing the slips 20 downwards to move the slips 20 downwards, so that the lower conical surface at the bottom of the slips 20 is in conical fit with the upper conical surface 11 of the cylinder 10, and the teeth are in a contracted state, as shown in fig. 4. In order to prevent the slips 20 from being deformed inward when the pressing plates 60 press the slips 20 downward, contact bodies 70, which are cylindrical bodies, are provided at the bottom of the pressing plates 60 to contact the inner walls of the top of the slips 20 to guide the deformation of the slips 20, and are inserted between the tops of the respective slips.

A coil spring 40 is disposed between the upper joint 30 and the pressing plate 60, and the coil spring 40 is used to provide a downward elastic force to the pressing plate 60 after being compressed to press the slips 20. The upper end surface of the pressing plate 60 is fixed with a guide rod 50 extending upwards, and the guide rod 50 comprises a guide rod body 51 extending along the vertical direction along the axis, a connecting rod 52 fixed at the upper end of the guide rod body 51 and having a diameter smaller than that of the guide rod body 51, and a top plate 53 fixed at the upper end of the connecting rod 52. The upper end of the guide rod body 51 passes through the frustum 35 and the round rod 34 upwards and penetrates into the lower cylinder 33, and the connecting rod 52 and the top plate 53 pass through the lower cylinder 33 and extend into the hexagonal prism 32, so that the guide rod through holes 36 which are vertically through are formed in the hexagonal prism 32, the lower cylinder 33, the round rod 34 and the frustum 35.

The hexagonal prism 32 is provided to facilitate screwing of the upper adapter 30 and screwing of the upper adapter 30 to the cylinder 10. In addition, when the down-hole junk fisher is not used for fishing and after the hanger is fished, a certain distance is reserved between the top plate 53 and the upper cylinder 31, in order to facilitate the removal of the hanger, insertion holes 37 for inserting external removal rods from the radial direction are formed in two opposite side walls of the hexagonal prism 32, the two insertion holes 37 are located in the same radial direction and are communicated with guide rod through holes in the hexagonal prism 32, so that the removal rods can completely penetrate through the hexagonal prism 32. In addition, the insertion holes 37 on both sides are also long holes extending in the up-down direction, so that the dismounting rod has a space for moving up and down, and can move up and down relative to the hexagonal prism 32, and the top plate 53 is located at a position just corresponding to the position of the insertion hole.

When the slip is used, two dismounting rods penetrate through the hexagonal prism 32 and are respectively positioned at two sides of the connecting rod 52, upward lifting acting force is applied to two ends of each dismounting rod by hands, the dismounting rods are matched with the bottom surface of the top plate 53 to drive the top plate 53 to move upwards, so that the bottom surface of the top plate 53 forms a matching structure matched with the dismounting rods on a guide rod, the pressing plate 60 moves upwards along with the top plate 53 when the top plate 53 moves upwards, the pressing on the slip 20 is relieved, the slip 20 can be reset upwards and opened along the conical surface of the inner wall of the bottom of the cylinder, and the clamping teeth can be separated from the fishing head.

The spiral spring 40 is sleeved outside the guide rod body 51, the bottom end of the spiral spring 40 is pressed against the pressing plate 60, the frustum 35 is provided with a frustum outer conical surface which gradually inclines inwards from top to bottom, the upper end of the spiral spring 40 is sleeved and pressed against the frustum outer conical surface, the spiral spring 40 can provide the maximum elastic pressing force for the slip, and the maximum outer diameter of the frustum 35 is larger than the inner diameter of the spiral spring. After the fishing tool is assembled, the coil spring 40 is in a pre-compressed state, so that a downward pressure is applied to the pressing plate 60, the pressing plate 60 presses the slip 20 downwards, and the clamping teeth of the slip 20 are in a contracted state, as shown in fig. 4 and 1, and the minimum distance a between the clamping teeth is smaller than the diameter b of the step surface of the fishing head.

In order to facilitate the release of the hanger when it is stuck, the present invention sets the outer diameter of the round bar 34 to be smaller than the inner diameter of the coil spring 40, the round bar 34 extends up and down and has a certain length, while the maximum outer diameter of the frustum 35 and the inner diameter of the coil spring 40 have a set diameter difference therebetween, this difference in diameter enables the helical spring 40 to be deformed radially when it is subjected to an upward thrust greater than a certain value, so as to partially pass over the frustum 35 and be fitted outside the rod 34, that is, a part of the number of turns of the coil spring may be transferred to the outside of the round bar 34 as shown in fig. 5, so that the number of turns of the spring fitted around the outside of the guide bar body 51 becomes smaller, thereby releasing the pressure to the pressing plate 60, and then the slip can move upwards and the clamping teeth are opened, and the minimum distance a' between the clamping teeth is larger than the diameter b of the step surface of the fishing head.

The assembly process of the underground junk fisher comprises the following steps:

firstly, the slips 20 are arranged in the cylinder body 10 from top to bottom, then the spiral spring 40 is sleeved outside the guide rod 50, the pressing plate 60 and the contact body 70 are arranged in the cylinder body 10 from top to bottom, finally the upper connector 30 is connected to the upper end of the cylinder body 10 in a threaded mode, the guide rod through hole 36 needs to be aligned with the guide rod when the connection is carried out, the guide rod penetrates into the upper connector 30, and the upper end of the spiral spring 40 is sleeved and pressed on the outer conical surface of the frustum after the connection.

The working principle of the underground junk fisher in the invention is as follows:

when the fishing tool is used, the fishing tool is connected with a fishing pipe column at the upper part through the upper part column body 31, then the fishing tool is put into a well along with the fishing pipe column, when the fishing tool reaches the position of the hanger, a fishing head of the hanger enters the barrel body 10 under the guide of the conical guide surface 12, then the fishing head pushes the slip 20 upwards to enable the slip 20 to move upwards, the spiral spring 40 is further compressed, the slip 20 resets and the clamping teeth stretch, the fishing head enters the inside of the slip 20, then the slip 20 moves downwards under the action of the spiral spring 40, the clamping teeth clamp the step surface on the fishing head, then the pipe column is lifted up to lift the hanger, and in the process, the clamping teeth tightly clamp the fishing head under the action of gravity of the hanger to achieve the effect of automatic locking.

The above process is the same as the prior art, and has two differences, one is that when the hanger is blocked and cannot be lifted out, the fishing pipe column on the upper part rapidly applies downward acting force to the fisher, namely the fishing head is hammered down, so that the fishing head rapidly impacts the contact body 70 and the pressing plate 60 upwards, and further the spiral spring 40 instantly receives larger upward jacking force, because a set diameter difference exists between the maximum outer diameter of the frustum 35 and the inner diameter of the spiral spring 40, when the upward jacking force is large enough, the spiral spring 40 can generate radial deformation, so that the spiral spring passes through the frustum 35 and is sleeved outside the circular rod 34, as shown in fig. 5, a part of circles of the spring are sleeved outside the circular rod 34 by repeatedly hammering down the fishing head, so that the circles of the spring sleeved outside the guide rod body 51 are reduced, and the pressing plate 60 does not have the capability of tightly pressing the slips 20 any more, the slips 20 are thus opened and disengaged from the fishing head, allowing release of the hanger.

After the hanger is released, the overshot is lifted out, and in order to enable the overshot to be reused, the upper joint 30 needs to be detached from the barrel 10, at this time, a part of the spiral spring is still carried on the round rod 34 and the frustum 35, and then the upper joint 30 is rotated by utilizing the spiral line characteristic of the spiral spring 40, so that the frustum 35 can rotate in the gap between the circles of the spiral spring 40, and the frustum 35 can be rotated out to realize the separation from the spiral spring 40. Therefore, the underground junk fisher can meet the releasing requirement when necessary, the spiral spring 40 is matched with the frustum 35 and the guide rod body 51, the installation is very convenient, in addition, the frustum can be screwed out of the spiral spring by rotating the upper joint 30 during the disassembly, the disassembly is also very convenient, and the repeated use of the fisher is convenient.

Another difference between the fishing tool for the underground junk and the prior art is that: after the hanger is normally lifted out, because the length of the whole tool string is large, the hanger is inconvenient to lift and move, the hanger can be firstly detached, at the moment, two detaching rods penetrate through the hexagonal prism 32, upward lifting acting force is applied to two ends of each detaching rod by hands, the detaching rods are in stop fit with the bottom surface of the top plate 53, the top plate 53 is driven to move upwards, the pressing plate 60 and the contact body 70 below are driven to move upwards synchronously, the clamping of the slip 20 is relieved, and the clamping teeth can be in an open state and can be separated from the fishing head.

In other embodiments of the fishing tool for the fallen objects in the well, the fishing tool for the fallen objects in the well can also be used for fishing other fallen objects in the well, such as a broken sucker rod, a pump core of an oil well pump, etc., as long as the fallen objects in the well are provided with the fishing heads as shown in fig. 1 to 3.

In other embodiments of the downhole fishing device, when the fishing head is knocked down, all the spiral springs can cross the frustum and are sleeved outside the round rod, and the elastic pressing force is also eliminated.

In other embodiments of the down-hole junk fisher, when the length of the spiral spring is longer, even if a part of the spiral spring is sleeved outside the round rod through the down-pounding fishing head, the number of the remaining spiral spring is still more, the downward pressing force is still applied to the slips, but the pressing force is smaller and far smaller than the elastic deformation restoring force of the slips, so that the slips can overcome the part of the pressing force, move upwards, reset and expand, and release of the down-hole junk is realized.

In other embodiments of the fishing tool for the fallen objects in the well, the upper joint does not include a round rod and a frustum, the upper end of the spiral spring directly presses against the lower cylinder of the upper joint, and in order to release the fallen objects when the fallen objects in the well are clamped, the upper conical surface and the conical guide surface at the lower end of the cylinder can be arranged in a split mode and connected to the cylinder through the shearing pin, so that when the lifting force is greater than a certain value, the shearing pin can be pulled off, the part is separated from the cylinder, and the fallen objects are released.

In other embodiments of the downhole junk latch, the bottom of the hold down plate may be provided without a contact, and the hold down plate presses the slips directly down.

In other embodiments of the down-hole junk fisher, the guide rod may also be only composed of a guide rod body, and at this time, a neck-reducing groove may be processed on the guide rod body, and a step surface of the neck-reducing groove forms a matching structure matched with the dismounting rod, or a radial through hole may be directly processed on the guide rod body, and the dismounting rod directly passes through the through hole, and at this time, the through hole forms a matching structure matched with the dismounting rod.

In other embodiments of the down-hole junk fisher, when the upper joint is connected with the barrel through threads, the hexagonal prism structure may not be arranged on the upper joint, for example, the whole upper joint is a cylinder structure, and the jack is directly machined on the cylinder, or even if the hexagonal prism structure is arranged on the upper joint, the jack may not be machined on the hexagonal prism structure, but may be machined on other parts of the upper joint.

In other embodiments of the down hole junk fisher, the upper joint and the barrel may not be in threaded connection, for example, the connection may be through screws, in which case, radially extending screw through holes may be provided on the barrel, and radially extending threaded holes may be provided on the upper joint, and the screws may be passed through the screw through holes and then engaged with the threaded holes on the upper joint, so as to fix the upper joint on the barrel, and in order to ensure the fixing effect, several screws may be provided.

In other embodiments of the down-hole junk latch, the insertion hole of the upper joint may not be a long hole extending up and down, but may have a diameter larger than that of the circular hole of the disassembling rod, so that the disassembling rod may have a space to move up and down.

In other embodiments of the downhole junk latch, there may be only one receptacle on the top sub.

In other embodiments of the downhole junk overshot, the connection structure on the upper connector for connection to the fishing string may also be other than external threads, such as internal threads, or may be a threaded connection, in which case the connection structure is a radially extending threaded bore.

In other embodiments of the downhole junk overshot, the slips may have only two flaps, but may have four or more flaps.

In other embodiments of the downhole junk overshot, the slips may not be separate, for example, the upper ends of the slips may be connected together by a ring.