Remotely operable downhole junk basket system

A remotely operable downhole basket for use at the bottom of a fishing string in a well bore has a tubular body. Inside the tubular body is a tubular finger basket having a plurality of slots in which fingers are pivotally mounted. The fingers are normally biased out of the slots into horizontal positions. At the bottom of the tubular body is a tubular opener. The outer side of the tubular opener is in a vertically sliding relationship with the inside wall of the tubular body. The opener is configured at its upper end to push the fingers into their respective slots. The tubular opener has an actuator shoe at the lower end of the tubular opener. The top end of the actuator shoe is adapted to abut against the lower end of the tubular body to stop upward travel of the opener relative to the tubular body. A circular return spring is positioned between the outer side of the tubular opener and the inside wall of the tubular body. The return spring exerts a force on the tubular opener which is downward relative to the tubular body.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to tools for retrieving items from the bottom of a 
well bore, and, more particularly, to tools for bringing the retrieved 
item back to the surface from the bottom of the well bore. 
Typical prior art tools for bringing to the surface items retrieved from 
the bottom of a well bore are disclosed in the following U.S. Pat. Nos. 
2,493,992; 2,520,783; and 3,203,491. These prior art tools, however, have 
various limitations. For example, the tools disclosed in U.S. Pat. No. 
2,493,992 can be actuated only once before withdrawing the entire fishing 
string. The embodiment shown in FIGS. 1 and 2 includes a junk basket 
arrangement that is closed by mechanical actuation of the tool, while the 
basket shown in FIG. 3 is actuated by use of an electromagnet. In each 
case, however, once the basket is closed, it is apparent that the basket 
cannot be re-opened without withdrawing the entire fishing string out of 
the well bore. Thus, it is not possible to lower an electromagnet through 
the basket, once the basket has been closed. The baskets disclosed in U.S. 
Pat. Nos. 2,520,783 and 3,203,491 have similar limitations. The basket 
disclosed in U.S. Pat. No. 2,520,783 is actuated mechanically, while the 
basket in U.S. Pat No. 3,203,491 is actuated hydraulically. In either 
case, an electromagnet can not be lowered through the basket once the 
basket has been closed. 
The present invention overcomes the above-noted and other drawbacks of the 
prior art by providing a remotely operable downhole junk basket system 
which allows an operator to open and close the basket as often as is 
desired while it is at the bottom of a well. Expressed otherwise, the 
basket can be opened more than once down the hole so that an electromagnet 
can be raised and lowered repeatedly through the basket. 
The invention in a general sense comprises an inner tubular member which 
fits within an outer tubular member in an axially or longitudinally 
slideable relation. The outer member is adapted to attach to the lower end 
of a pipe string; it serves as a tubular driver in transmitting axial or 
torque loadings from the pipe string. The inner tubular member serves as a 
tubular opener; it provides an opening through which a fish in a well may 
be retrieved. The lower end of the inner tubular member preferably 
comprises a bit, a washover shoe, or other tool for engaging the bottom of 
a well. 
A lower internal wall portion of the outer tubular member or tubular driver 
and an upper external wall portion of the inner tubular member or tubular 
opener are configured to define one or more annular chambers or cavities 
to house springs which are compressed upon upward axial movement of the 
inner tubular member relative to the outer tubular member. The spring or 
springs thereby urge the inner tubular member downward relative to the 
outer tubular member when the two members telescope together. 
A junk catcher or basket is mounted in the internal wall of the outer 
tubular member above the spring chamber or cavity. The catcher or basket 
comprises a cylindrical housing with a plurality of arcuately spaced 
internal openings to house a corresponding plurality of fingers. Each 
finger is spring-loaded and pivotally mounted at its lower end in its 
respective opening to extend radially inward in a lateral, or transverse, 
position. In their transverse position, the fingers overhang the upper end 
of the inner tubular member, such that upward movement of the inner 
tubular member relative to the outer tubular member forces the fingers 
into their retracted vertical positions within the basket. Preferably, the 
inner tubular member is provided with sufficient axial travel such that 
its upper end can slide within the basket with the fingers in their 
retracted position. 
Releasable interlocking means may be employed to hold the inner and outer 
tubular members telescoped together with the basket fingers in their 
retracted vertical position. A preferred such means is a shear pin which 
may be sheared by bumping the inner tubular member against the bottom of 
the well. 
When the two tubular members are telescoped together, a junk retriever such 
as a hook or an electromagnet may be lowered on a wire line, reelable 
tubing or the like down through the basket to a piece of junk, a fish, or 
other object at the bottom of a well. The retrieved object may then be 
lifted above the retracted fingers. The fingers may then be released to a 
lateral position to form the bottom of a basket, to hold the retrieved 
object. If desired, as for example when employing an electromagnet, the 
basket itself may be used to carry the object to the surface of the earth.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1, there is illustrated the environment in which a 
remotely operable downhole junk basket built according to the present 
invention may be used. A junk basket system 10 is connected to the lower 
end of a fishing string 12. More particularly, an adapter 13 connects the 
junk basket system 10 to the lower end of the fishing string 12. The 
fishing string 12 is typically composed of a plurality of sections 14 of 
drill pipe. As additional sections 14 are added to the fishing string 12, 
the fishing string 12 is lowered further into the well bore 16. This 
process of adding additional sections 14 of drill pipe continues until the 
junk basket system 10 reaches the bottom of the well bore 16. From above 
the ground 18 an electric cable 20 is inserted into the fishing string 12. 
Attached to the end of the electric cable 20 is a retrieval device, 
preferably an electromagnet 22. The electromagnet 22 is lowered through 
the remotely operated junk basket system 10 until the magnet 22 contacts a 
piece of junk 24, such as a broken drill head, at the bottom of the well 
bore 16. Then the electromagnet 22 is energized by means of the electric 
cable 20, thus causing the piece of junk 24 to attach itself to the 
electromagnet 22. The piece of junk 24 is then raised above the junk 
basket system 10, the junk basket system 10 is closed, and then the 
electromagnet 22 is deenergized, causing the piece of junk 24 to fall into 
and be caught by the junk basket system 10. 
Referring to FIG. 2, the junk basket system 10 includes a finger basket 26, 
illustrated in a perspective view, having a tubular body 28. Referring to 
FIG. 3, the finger basket 26, illustrated in a top view, has fingers 30 
which open and close. In FIG. 3 the fingers 30 are depicted in a closed, 
or extended position. Each finger 30 has a corresponding spring 31 which 
forces the finger 30 into the closed, or extended, position. The fingers 
may all be the same length, or may be various lengths, depending on the 
diameter of the tubular body 28 and depending on the size and weight of 
the piece of junk 24 expected to be retrieved. However, in a preferred 
embodiment alternate fingers are longer than the rest of the fingers. 
Although FIG. 3 illustrates eight fingers 30, there may be any number of 
fingers 30. In a preferred embodiment, in which the junk basket system 10 
has an outside diameter of nine inches, there are twelve fingers 30. The 
fingers 30 may be made of any suitable material, but in a preferred 
embodiment they are made of cast bronze. The width 32 may be any suitable 
width depending on the number of fingers 30 and the inside diameter of the 
junk basket system 10. 
Referring to FIG. 4, the junk basket system further includes a tubular 
opener 33. The tubular opener 33 at its lower end has an actuator shoe 34. 
The actuator shoe 34 has a bottom end 35. The bottom end 35 has an edge 36 
for contacting, scouring or dragging against the bottom of the drill hole 
16. The bottom end 35 is preferably one piece with the actuator shoe 34. 
The tubular opener 33 is in a sliding relationship with a tubular driver 
40, which is threaded to the bottom of the fishing string 12. 
Four driver bolts 42 are inset within the driver 40 and are threaded into 
screw holes 44 in the tubular opener 33. Near the lower end of the driver 
40--e.g., about one inch from the bottom of the inside wall of the driver 
40--are four drive key slots 46, through which a driver bolt 42 passes, 
bolted to a drive key 47 which slides in the drive key slot 46. The four 
drive key slots 46 are spaced approximately ninety degrees from each 
other. Each drive key slot 46 is just wide enough to allow the drive key 
47 to slide in it. The close sliding relationship between the drive key 
slots 46 and the drive keys 47 allow torque applied to the tubular driver 
40 to be efficiently transmitted to the actuator shoe 34. Thus, rotational 
movement of the tubular driver 40 causes the bottom end edge 36 to rotate, 
which rotation may be used to scrape the bottom of the well bore 16. 
Each drive key slot 46 is a slot which has a length 48, which length 48 is 
substantially one-half the length of the longer fingers 30. The length 48 
of the drive key slot 46, minus the length of the drive key 47, is the 
length of the travel 49 which the actuator shoe 34 can travel in sliding 
relationship with the driver 40. Thus, the key slots 46 must be long 
enough to enable the fingers to be actuated between an extended, closed 
position and a retracted, open position in response to movement of the 
tubular opener 33 relative to the driver 40. 
In a preferred embodiment, a short distance above the drive key slots 
46--for example, approximately one and one-half inches above the top of 
the drive key slots 46--the tubular opener 33 is cut inwardly about 
two-thirds of its thickness for the rest of its length, thus forming a 
ledge which acts as a spring catch 50. Above the spring catch 50 the inner 
one-third of the thickness of the tubular driver 40 extends 
upward--typically about four and one-half inches--such that when the 
tubular opener 33 is slid as far down as the driver bolt 42 sliding in the 
drive key slot 46 will allow the tubular opener 33 to slide, a top end of 
the tubular opener 33, acting as a finger catcher 52, is below a bottom 
edge 54 of each finger 30, when the fingers are in their extended, 
horizontal position, as shown in FIG. 3. 
The driver 40 has an annular protrusion 56 which extends inwardly a 
distance of substantially two-thirds the thickness of the tubular opener 
33 so that the finger catcher 52 is in a sliding relationship with the 
inner edge of the annular protrusion 56. An outside wall 58 of the tubular 
opener 33, an inside wall 60 of the driver 40, together with the spring 
catch 50 and a bottom edge of the annular protrusion 56, form a cavity 62 
in which a circular return spring 64 exerts a force downward on the spring 
catch 50. 
Resting on top of the annular protrusion 56 is the finger basket 26. The 
outer surface of the tubular finger basket 26 is in a loose, sliding 
engagement with the inner surface of the tubular driver 40, to allow the 
finger basket 26 to rotate freely within the tubular driver 40. In 
alternate embodiments, thrust bearings are inserted in the tubular driver 
40 above and below the finger basket 26 to aid in the rotation of the 
finger basket 26 within the tubular driver 40. The finger basket 26 
includes pivots 68 around which each finger 30 pivots. When force is 
exerted against the bottom end 35, the tubular opener 33 rises until a top 
end 70 of the actuator shoe 34 abuts against a driver bottom end 72 of the 
driver 40. Before the actuator top end 70 abuts against the driver bottom 
end 72, the finger catcher 52 abuts against the bottom edge 54 of each 
finger 30, pushing each finger 30, against the force of the spring 31, 
into a slot 74 in the finger basket 26. Thus, when the fingers are pushed 
into the slots 74, the edges 54 are in the same plane as the inside wall 
of the fishing string 12. 
Referring now to FIG. 5A and FIG. 5B, the tubular driver 40 has an aperture 
78 adapted to receive a shear pin. The tubular opener 33 has an aperture 
80 with a diameter substantially three times as large as the diameter of 
the aperture 78. The aperture 78 has threads 82 adapted to receive a set 
screw 83. The apertures 78 and 80 are located below the drive key slots 
46. The apertures 78 and 80 are aligned when the bottom of the tubular 
opener 33 does not press against anything. When the driver 40 is pressed 
down in relation to the tubular opener 33, an aperture 84, located in the 
tubular opener 33 below the aperture 80, becomes aligned with the aperture 
78. When apertures 78 and 84 are aligned, the fingers 30 are in their 
respective slots 74. 
As shown in FIG. 5A, a shear pin may be inserted into the aligned apertures 
78 and 84, thus keeping the fingers 30 pushed by the finger catcher 52 
into their respective slots 74. Thus, when the apertures 78 and 84 are 
held in alignment by a shear pin 85, keeper means are provided for keeping 
the fingers 30 in their respective slots 74 before the bottom end 35 of 
the actuator shoe 34 presses against the bottom of the well bore. 
With a shear pin inserted in the aligned apertures 78 and 84, a gap 77 
exists between the bottom end 72 of the tubular driver 40 and the top end 
70 of the actuator shoe 34. The gap 77 is larger than the diameter of the 
shear pin to ensure that there is enough room for movement of the shoe 34 
upwards to shear the shear pin 85. In the preferred embodiment, the shear 
pin diameter is three-sixteenths inch and the gap 77 is one-quarter inch. 
The aperture 84 has a pinhole 86 through which a pin may be inserted to 
push out the part of the shear pin remaining after the pin has been 
sheared. 
In operation, when a piece of junk or "fish" 24 is at the bottom of the 
well bore 16, the junk basket system 10 is attached to the bottom end of 
the fishing string 12, and then the fishing string 12 is lowered into the 
well bore 16 until the bottom end 35 of the tubular opener 33 rests 
against the fish 24 or the bottom of the well bore 16. Preferably, the 
tubular opener 33 is telescoped within the tubular driver 40, and is held 
in position by a shear pin extending through apertures 78 and 84. Then the 
weight of the fishing string 12, with the adaptor 13 attached to the 
bottom, is allowed to push downward on the upper edge 76 of the tubular 
driver 40, shearing the shear pin and enabling the actuator top end 70 to 
abut against the driver bottom end 72. As the fishing string 12 presses 
the driver 40 downward, the finger catcher 52 presses the fingers 30 into 
the slots 74. 
The operator can then lower the electromagnet 22 to the bottom of the well 
bore 16, collect the piece of junk 24, and then lift the piece of junk 24 
above the tops of the fingers 30. At that point in time, the operator need 
merely lift the fishing string, together with the electric cable 20 and 
the electromagnet 22, a few more inches, and the return spring 64 then 
forces the finger catcher 52 down away from the fingers 30, allowing the 
springs 31 to force the fingers 30 to extend in their transverse, or 
horizontal, positions. The operator may then deenergize the electromagnet 
22, thus dropping the piece of junk 24 on top of the extended fingers 30. 
When using a shear pin in the apertures 78 and 84 to keep the junk catcher 
fingers open before the actuator shoe presses against the bottom of the 
well bore, the operator first inserts a shear pin in the aligned apertures 
78 and 84, and then screws in a set screw in the threads 82 to keep the 
shear pin in the aligned apertures 78 and 84. As indicated earlier, the 
operator may then shear the pin by allowing the actuator shoe 34 to bump 
against the bottom of the well. When the actuator shoe bumps against the 
bottom of the well, the tubular opener 33 moves upwardly in relation to 
the tubular driver 40. This movement shears the shear pin 85. 
After the operator has sheared the pin and has raised the junk basket 
system 10 to the surface, the operator has two shear pin fragments to 
remove. For the fragment in the aperture 84, the operator inserts a pin 
through the pinhole 86 and pushes the fragment of the shear pin out of the 
aperture 84. 
For the fragment in the aperture 78, the operator pushes the fragment out 
of the aperture 78, and through and out of the aperture 80, the center of 
which is aligned with the aperture 78. As the aperture 80 has a diameter 
larger than the diameter of the aperture 78, the shear pin fragment is 
easily pushed through the aperture 80. Although the circular return spring 
64 can be compressed to align the apertures 78 and 84, it can not be 
easily done by one person. The aperture 80 provides the way to remove the 
shear pin fragment from the aperture 78 without compressing the circular 
return spring 64. 
The principles, preferred embodiments and modes of operation of the present 
invention have been described in the foregoing specification. The 
invention is not to be construed as limited to the particular forms 
disclosed, since these are regarded as illustrative rather than 
restrictive. Moreover, variations and changes may be made by those skilled 
in the art without departing from the spirit of the invention.