US 2613980 A
Description (OCR text may contain errors)
Oct.7 14 1952 K, C, HAWKINS 2,613,980
FISHING TOOL Filed March 13, 1950 HUE' BNE 1?,.85 E HL E R WORRE L y HERZ/G 8 CALDWELL,
Patented Oct. 14, 1952 UNHTED STATES PATENT FFICE 25,613,980
y msnm@ rrootJ Kenneth e. Hawkins, Arcadia, cani. Application March 13, 1950, Serial No. M926@ 3 Claims.
application relates to shi'ng tools particularly adapted to retrieving magnetiaable obiects from well casings and to tools which are found particularly advantageous in deep well casings of the type used extensively in sinking oil wells. 5
In oil well '.irilling where it is the practice to sinh oil wells into the earth accompanied by steel oasings to distancesA of thousands of feet drilling operations become particularly expensive. Al.- though tools have been contrived which may eventually bring objects in the well to the suriaoe, excessive time consumed in suchoperations interferes 'with or interrupts the drilling before vthe desired depth is reached and causes objectionable and sometimes prohibitive loss of time frequently jeopardizing the economic success of the operation. Therefore when objects such as wrenches, drill bits, sections of pipe and the like inadvertently fall into the casing the time and snort required to retrieve them is a substantial factor in drilling operations. 'Moreoven the deeper the well, the more time is lost espeoially when objects, partly retrieved, are lost or dropped a second time making necessary new efforts to lift them.
Heretofore a great variety of fishing tools have been devised utilizing one mechanical expedient or another for grappling objects which have fallen into the well with a sufficiently tight grip so that they may be hauled upwardly out of the casing throughout distances of some thousands of feet. Naturally the greater the depth of the well the longer is the time needed to lower and raise the shing tool.` Unless the grip of the tool on the object to be retrieved is sufficiently' secure, the hold on the object may be dislodged one cr many times before the object is nally pulled out of the casing at the surface. The cost of the shing operation is therefore increased a considerable extent whenever the object is not successfully retrieved during the rst fishing operation. Y
inasmuch as almost all objects which are likely to fall into a drilled well are of a ferrous and therefore magnetic nature, the use of a magnet for retrieving the objects has suggested itself in the past.v The character of a Well is, however, such that using a magnet has heretofore presented such difficulties that successful utilization of magnets for this purpose has been defeated. The fact that the well casing is of a magnetic material short circuits the magnetic field, thereby reducing its strength to an unworkable quantity when the magnet and sometimes the object itself strikes against the interior of the casing.
When the object is of irregular shape the 'grip of the magnet may be dislodged by reason of the object bumping against the well casing on the way up even though the strength of the magnet lis not materially reduced. lSome objects which need to be retrieved are so heavy that the strength of the magnet cannot be depended upon to continue to attract the object with suiiicient force throughout the entire lift from the bottom of the well to the surface.
It is therefore among the objects of the invention to provide a new and improved magnetic. shing tool for well casings kwhich is adapted to retrieve metallic objects of any and all sizes which are ordinarily dropped into the well.
Another object of the invention is to provide a new and improved magnetic iishing tool which utilizes an auxiliary retainer or grappling device to provide an independent grasp upon the object to be retrieved whilel it is being lifted to the surface of the well. v
Still another object of the invention is to provide a new and improved metallic fishing tool which is so constructed that the magnet is shielded from contact with the casing so as to maintain sufficient effectiveness in the force of the magnet throughout the entire lift from the bottom of`the well to the surface.
Still another object of the invention is to provide a new and improved magnetic iishing tool for wells by which an auxiliary retainer or grappling device can he released when the object to be retrieved is drawn to the magnet so that the retainer forms either a support upon which the object may be rested while drawn to the surface or which, for objects of considerable length, may be moved so as to grip the exterior of the object in a way such that no matter how great the pull may be upon the object the grip will be held until the object is lifted clear of the well.
Still further among the objects of the invention is to provide a new and improved magnetic nshing tool for wells wherein a magnet is movably retained in a casing in a manner such that it can bel 'extended to a position most advantageous for initially engaging an object to be retrieved and thereafter withdrawn tegether with the object to a'position in the casing wherein the object if need be may be grasped by some auX- iliary mechanism, thereby adding to the grip upon the object while the fishing tool is being withdrawn together with the object from the well.
VWith these and other objects in View, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.
In the drawings:
Figure 1 is a longitudinal sectional View of the magnetic fishing tool with the parts in initial position shown being lowered into a well casing.
Figure 2 is a longitudinal sectional View of the fishing tool showing its operation in grasping an object to be retrieved which has a length greater than the length which could be accommodated within the fishing tool.
Figure 3 is a longitudinal sectional view of the fishing tool shown in engagement with a relatively small object for lifting the object from a well.
Figure 4 is a cross-sectional view taken on the line 4--4 of Figure 1.
Figure 5 is a fragmentary longitudinal sectional view showing one form of grappling means in an initially withdrawn position as for lowering into the well.
Figure 6 is a longitudinal sectional View of a modiiied form of the device showing a permanent magnet.
Figure 7 is a cross-sectional view taken on the line 'I-1 of Figure 6.
When using magnetic force to recover, retrieve and withdraw a magnetizable object from a deep well special precautions need be taken to assure a suflicient grip upon the device no matter what its shape while it is being attracted te the area within which a proper grip may be secured upon it and also during the entire lift of the device from the bottom of the well to the surface. In the magnetic fishing tool of the present invention the tool includes a container for the magnet which opens downwardly in such a manner that when the objects to be retrieved are within the iield of attraction of the magnet they may be drawn to a position with respect to the iishing tool so that a iirm grasp upon the objects may be l.
assured at all times regardless of the size or shape of the object or the character of the interior of the well casing in which the iishing tool is used.
As shown in the drawings there is depicted a section of steel well casing I which may be assumed to be at any depth which might ordinarily be reached by conventional well drilling methods. A magnetic fishing tool indicated generally by the reference character I I is shown being lowered into the casing I0 by means of a cable I2 secured to the tool by a cable connection I3.
The iishing tool comprises in the example chosen a cylindrical container I4 of somewhat elongated character which has its upper end closed by a cover I and which has a lower open end I6. The container should preferably be of a non-magnetic material such as copper or aluminum so as to form an eiiective shield to prevent anything within the container having a magnetic contact with the steel of the casing I0.
Within the casing is a piston I1 having a sliding packing I8 so that the piston forms a closed chamber I9 within the container. A tting 20 mounted in a cover I5 provides access to the chamber I9 through a iiexible hose line 2| which connects tc a shut-off valve 22 located above and outside of the casing ID. By this means the chamber I9 may be iilled with a suitable iiuid under pressure if desired and by means of which the contents of the chamber may be exhausted.
Mounted upon and below the piston I1 is a coil 23 of an electro-magnet supplied by one wire 24 to one terminal 25 of the electro-magnet. The other terminal may be grounded if desired through the cable I2. The wire 24 may be helical or in any event extendible by some conventional means and permanently secured to a binding post 26. From the binding post a wire 21 may extend upwardly through the casing to a suitable source of electric power.
To complete the electro-magnet there is shown a stationary core 28 of magnetizable material, a cylindrical portion 29 of which forms a center for the coil 23 and a lower portion 3U of which forms a flat face for the magnet. The core is shown threadedly engaged at 3l with the piston so that the piston and the magnet act as a single unit.
For proper protection of the winding of the magnet there may be provided a non-magnetic wrapping 32 entirely surrounding the coil and the outer circumference of the portion of the core extending below the coil. It will be appreciated that fishing tools of this kind when extended deep into wells are apt on occasions to be entirely submerged in mud and water so that proper protection for the magnet is advisable. There must, however, be a suflicient clearance between the magnet and the inner wall of the chamber I9 so that the magnet and piston unit can raise and lower with perfect ease.
At the lower end of the container I4 there may be provided a shoulder 35 upon which a complementaiy shoulder 36 on the magnetic core is adapted to rest, thereby permitting a lower face 31 of the magnetic core to extend outwardly substantially iiush with the outside open end of the container I 4.
In Figure 1 the electro-magnet is shown in its lowermost or extended position which is the position it would have While being lowered into the well.
Figures 2 and 3 show the electro-magnet and piston unit in withdrawn position removed from the open end of the container. This is the position the electro-magnet piston unit will assume after the object has been attracted to it and the electro-magnet withdrawn to the position it will occupy while the fishing tool is lifted from the well.
At the lower end of the container there is provided a retaining means which in the selected embodiment is shown as comprising oppositely disposed arms 40 and 4I, 42 and 43. As shown in greater detail in Figure 5 with respect to the arm 40 the container is provided with a recess 44 adapted to receive the arm in a position sufiiciently withdrawn so that the electro-magnet piston unit is free to slide downwardly to lowermost position. The arm is shown pivoted by means of a pin 45 to the lower end of the container and the stored energy of a spring 46 located behind the arm may be utilized to force the arm outwardly after the electro-magnet piston unit has been lifted to a withdrawn position in the container I0. The arm may also be provided with a serrated or roughened section 4l adapted for use on special occasions in grasping the object which is to be removed.
In operation fluid is pumped into the chamber I9 through the shut-off valve 22 and hose line 2| so as to force the piston to lowermost position. This is the position shown in Fig. 1. With the piston in this position the shut off valve is closed and the container loweredby means of the cable I2 into the well casing. The core of the electro-magnet will be at its outermost position substantially ush with the lower end of the casing during this operation.
When the fishing tool reaches the bot-tom of the well the magnetizable object to be retrieved will be drawn to and attach itself by magnetic force to the exposed core of the electromagnet'. During this phase of the operation the electromagnet may be supplied withV current through the wire 24.
After theY attraction has been accomplished the piston together with the electro-magnet is Withdrawn into the container to a position removed from the lower open end. These are'the positions shown in Figures 2v and 3. This is accomplished by opening the shut-off valve 22 permitting the uid in the chamber i9 to bev discharged. The shut-off valve 22 is then closed again and the tool is lifted to the surface. As the piston is raised, the wire 2li coils upon it self to the position shown in either Figure 2 or 3.
Movement of the electro-magnet together with the piston as thus -shown serves, in Figure to draw a section of pipe 48 upwardly and into the lower end of the container. Where as in this example the section of pipe is too longY to be entirely withdrawn into the container, the section of pipe is grasped by the arms @il and 4I, 42 and 43. The grasp of the arms becomes effective as the electro-magnet is lifted upwardly clear of the arms in the positions illustrated in Figure 5. After the electro-magnet has cleared, springs 4t will force the arms inwardly so that opposite arms are urged toward each other and into contact with the exterior surface of the object which in this case is the section of pipe 48. Upon engagement the serrated portions of the arms grip the exterior surface of the section of pipe and the weight of the pipe will cause the section of pipe to jam between opposite arms and thus provide a satisfactory grip for the arms upon the section of pipe. The section of pipe thus secured is withdrawn to the surface by lifting upon the cable I2. Thus engaged it will not matter that the section of pipe touches the interior of the steel casing since because of the auxiliary grip of the arms there will be no short circuiting of the magnetic field such that it will cause the section of pipe to be released. in fact the electric coil may be deenergized once the section of pipe has been grasped and mechanical means depended upon solely for holding the section of pipe while it is being lifted to the surface.
In the example illustrated in Figure 3 the object to be retrieved may be an object such as a large nut 50 still small enough to enter completely within the lower end of the container it. In this example after the nut has attached itn self to the core of the electro-magnet and has been drawn inwardly into the casing, es the electro-magnet and piston rise to the withdrawn position, the arms MJ and si, 52 and 23 will drop forming a temporary false bottom for the con tainer. The width of the arms is somewhat arbitrary and may be proportioned as desired so that the arms when lowered to the position shown in Figure 3 may cover substantially all or only a part of the open end. of the container lil. The electro-magnet will--of course remain energized until the nut is lifted clear of the arms. In their initial position as illustrated in Figure 5 thesprings- 4f! willpush thel arms inwardly to a point from which they will then drop by gravity to theY positionsshown in Figure 3. In the lowermost position there illustrated thel arms may be retained upon the shoulder Sii which initially served to bottom the electro-mae net.- Once the arms are dropped to the position shown in Figure 3 the electro-magnet may be dee-energized and the object will be securely heid by the arms until it is lifted to the surface. l In the modified form ofthe device shown in Figures S--and -7 there is illustrated a permanent magnet 6l),l here shown as a double-pole magnet, having. two north poles lfill and 62 and two south poles 63 and Sil. Where a grip of lesser strength is satisfactory a single-pole magn net may suffice. In the particular example chosen for illustration the north and south pole pieces are retained'against a magnetic disk 65 forming a piston by means of a bolt 6E and a washer Eil. The disk 55 may be provided with arpacking ring 68, thereby serving as a piston adaptedY for -reciprocation sliding along the in ner wall 69 of the casing I4. Movement of the piston 55 is accomplished by the same fluid agency as described in connection with Figure l.
In using a permanent magnet thel object to be retrieved will at all times be drawn toward the permanently magnetized poles. Although the magnet will at all times be shielded from contact with `the interior of the casing it by the interposition of the non-metallic jacket or container lll, it is conceivable that the object to be retrieved might be so long that it protrudes outwardly below the container and also that it might be of such character that it could not be iirmly gripped by the arms fill and il, i2 and d3. Under these circumstances the forces of the magnet entirely would have to be relied upon to hold the object in attracted position to the fishing toolv until the tool could be lifted clear of the well casing. Because the object to be retrieved is of a magnetizable character is therefore becomes particularly important that the magnet be shielded or guarded from direct contact with the wall of the casing which otherwise would tend to short circuit the magnetic field and diminish the magnetic force to a point where it would be likely to lose its grip upon the object being retrieved. Clearly too in the last exame ple for objects small enough to be entirely withn drawn into the casing by action of the perinanent magnet, both the magnet and the objects are positively shielded from contact with the walls of the casing so that even if the operationA of arms 4i), el, 42 and 43 were defective or jammed the magnetic force would continue undiminished by any short circuit to the end that the object` could be .lifted throughout the full distance from the bottom of the well without becoming dislodged.
0n some occasions Where the object to be re-1 trieved might not be of any substantially great weight the magnet need not be extended to its lowermost position but lowered in withdrawn po-l sition in which position itcould be sunk to a point where the object would be within the field of the magnet and the object thereby drawn into the open end of the container into contact with the magnet and even past the arms without it being necessary to manipulate the magnet within the container.
Once the fishing tool accompanied by the retrieved object has been lifted clear of the well the arms can be pressed back sufficient to release the object from the tool. Releasing of ythe object may be facilitated by laying the fishing tool on its side or on some occasions turning it upside down so as to make easier the operation of releasing the arms, In `the case of small objects held by the permanent magnet release may be more readily accomplished by forcing the iiuid into the chamber I9, thereby shifting the magnet to extended position in which position the retained object can be more readily dislodged.
Accordingly there has been provided a mechanism making the use of magnets in retrieving ob- Ijects from deep wells especially advantageous and successful which is clearly adapted to operate with great assurance regardless of -the size or shape of any magnetizable object which could fall into a well. It will be appreciated of course that in view of the fact that the diameters of well casings vary to some extent, fishing tools would be made small or large depending upon the size of the casing worked without, however, in any way altering lthe principle of operation of the device.
While I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within Ithe scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.
Having described my invention, what I claim as new and desire 'to secure by Letters Patent is:
1. A shing tool for retrieving magnetizable objects from well casings comprising a, hollow container, a magnetic piston unit slidably tting within said container forming a closed chamber therein, said magnetic piston unit having a withdrawn position within the container and an extended object-engaging position at the lower end of the container, a iluid connection from Athe chamber to the surface and a shut-oli valve on the connection, a uid in said chamber adapted to be admitted thereto through said connection, said fluid being operable upon opening of said shut-off valve when the container is in the well to effect movement of said magnetic piston unit to withdrawn position, retaining means on the container for said magnetizable objects, said retainer having an object-engaging position and means adapted automatically to move said retainer to said object-engaging position.
2. A shing tool for retrieving magnetizable objects from well casings comprising a hollow cylindrical container of non-magnetic material, a piston including a magnet slidably tting within said container forming a closed chamber therein, said piston and magnet having a withdrawn position within the container and an extended obj ect-engaging position at the lower end of the container, a iiuid connection from the chamber to the surface and a shut-oil valve on the connection, a
o Number 8 fluid in said chamber adapted to be admitted thereto through said connection, a non-magnetic cover for said magnet, a retaining means movably attached to the container at the open end thereof adapted to engage said objects, said retainer having a normally inoperative position and having an operative position adapted to engage the exterior of an object to be retrieved, and means adapted automatically to move said retainer to object-engaging position.
3. A iishing tool for retrieving magnetizable objects fromwell casings comprising a hollow cylindrical container of non-magnetic material, a piston slidably iitting within said container forming a normally closed chamber therein, said piston having a withdrawn position wherein the volume of the chamber is diminished and an extended position wherein the volume of said chamber is expanded, a shut-01T valve outside the casing, a fluid connection from the chamber to the shut-off valve, a fluid in said chamber adapted to be admitted thereto under pressure through said connection, said iiuid being operable upon opening of said shut-off valve to effect a movement of the piston to the withdrawn position, an electro-magnet on said piston having a core extending vto the lower face of the magnet and an operating device outside the casing connected thereto, a non-magnetic cover for said electromagnet, mutually opposed retainers for said objects having pivotal connections to the container near the open end thereof and oppositely disposed roughened surfaces thereon, a stop shoulder on the container at said open end cooperable alternately with the plunger in extended position and with the retainers when extended during said withdrawn position of the piston, said retainers having lowered positions engaging the shoulder forming a bottom for the container in one objectengaging position and partially lowered positions in another object-engaging position wherein the roughened faces are in mutually opposed relationship adapted Ito grasp the exterior of an object to be retrieved, and automatically extending means for said retainers adapted automatically to move said retainers to said object-engaging positions.
KENNETH C. HAWKINS,
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Name Date Eastwood Nov. 1, 1910 Erwin Aug. 24, 1937 Brantly May 23, 1939 Murphy et al. Jan. 10, 1950 Kirby Jan. 30, 1951