US 3020079 A
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Description (OCR text may contain errors)
` Patented Fel). 6, L1962 of Germany Filed Sept. 29, 1959, Ser. No. 843,183 7 Claims. (Cl. 294-655) This invention relates to magnetic grappling mechanism for loose parts of well drilling apparatus lost at the bottom of the well, and particularly to such mechanism wherein accidental loss of retrieved parts is avoided.
When drilling wells for the recovery of petroleum, the drilling apparatus sometimes breaks. Many various grappling devices have been developed for the recovery of the loose broken pieces. These devices must be adapted to special cases and endeavor to make it possible to remove the blockage to the drilling apparatus in the shortest possible time.
For the recovery of smaller metal parts of the drilling apparatus, such as broken cutters or rollers lost from drill bits, a magnetic grapple vcomprising multiple magnets is usually inserted to bring the metal vparts from the bottom of the well to the surface.
At times the magnetic grapple is4 drawn from the well bottom without results. The most frequent cause of this failure is that the grapple magnets actually attract and pick up the metal parts from the bottom but these parts are lost again as the string of rods is being raised. Since the magnetic contacting surfaces between the metallic parts and the magnets are of rather small area, the magnetic holding forces are weak and only relatively slight resistance is sufficient to pull'or scrape the recovered parts from the magnets. Rubbing against the uneven wall of the well or against the tubing or hard shocks, such as may occur when stacking the rods, can cause the recovered material to be lost.
In accordance with this invention a mechanism is provided in which the magnet is surrounded by a movable protective pipe or the like which is provided with grappling means such as springs in order to prevent loss of the retrieved parts.
It is a major object of the invention to provide a novel loose metal part recovery device comprising magnetic means adapted to be lowered into a well and having special arrangements for preventing metal objects picked up thereby from being lost as the device is raised.
A further object of the invention is to provide a novel mechanism protective arrangement for a magnetic recovery device.
Another object of the invention is to provide a novel magnetic recovery device wherein the magnet has associated therewith apparatus that is normally inoperative as loose metal parts are picked up by the magnet but which becomes operative as the magnet is raised to prevent loss of the retrieved parts.
Another object of the invention is to provide a novel magnetic recovery device wherein a magnet is surrounded by a relatively movable protective shield that has means for effectively closing blocking its lower end to prevent loss of parts retrieved by the magnet.
Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawings wherein:
FIGURE l shows apparatus according to a preferred embodiment of the invention before retrieving the metal parts; and
FIGURE 2 shows the relation of elements after retrieving.
The magnetic grappling mechanism comprises a magnet 1 which is rigidly connected to the supporting rod by the connectingl tube 2. The magnetl is surrounded by a protective pipe 3 which is non-magnetic in its lower portion 3a. The upper edge of pipe 3 carries a safety ring 4 having an internal annular flange 4. Grappling springs 5, which are capable of being retained in inoperative position, are mounted'at the lower end of pipe 3. These springs are released by raising the magnet, through an annular release device lwhic'h is at a fixed distance from the magnet surface.
When the mechanism is assembled the coil spring 7, which surrounds tube 2 and is axially disposed between shoulder 8 on the connecting tube-2 and shoulder 9 on the protective pipe 3, is placed under compression and held by means of the shear pin 10 interconnecting tube 2 and pipe 3. When the protective pipe 3 is put down on the bottom ofthe well, the pin 10 shears and when the rod is lifted to raiseV tube 2 the protective pipe 3 is at first maintained on the bottom bythe spring action of expanding coil spring 7 while the rising magnet pulls the retrieved metal parts into the interior of protective Then the release device 6 frees the grappling springs 5 as it passes them and these springs eifectively close the protective pipe below the magnet.
As the rod is lifted further, the shoulder 8 on the f'connecting tube 2 may engage beneath the safety ring flange 4 and pulls the protective pipe along with it to the surface.
The magnetic body 1 has in its center a channel 11 through which the drilling mud in the well can circulate. vIt will be noted that permanent magnet 1 is annular and surrounded by pipe 3. The spring finger retainer device 6 is also a ring and, in the position of FIGURE l, it restrains the spring leaves 5 from projecting into the interior of the pipe. Each spring nger 5 is a bent leaf `or blade of spring metal fixed to pipe 3 at one end as by a fastener 5 and held stressed in retracted position in internal slot 5" substantially ush with the pipe bore by ring 6. Y
As tube 2 is raised by the rod or string of rods assembly leading up out of the well magnet 1 rises with respect to pipe 3. Pin 10 is sheared at this time and the weight on tube 2 is enough to prevent expansion of the spring 7 until tube 2 is sufficiently raised to permit it. In the FIGURE l position spring 7 actually urges pipe 3 toward the well bottom.
After tube 2 raises a certain amount a shoulder 11' on the magnet, or the tube 2 if desired, engages a flange 6 attached to restraining ring 6 and the ring 6 is raised relative to pipe 3 until springs 5 are freed to spring out into the interior of pipe 3 which is otherwise open at its lower end.
Then as the magnet 1 and ring 6 continue to rise together the flange 6' may become interposed between shoulders 11 and 9 to raise to pipe 3 to the surface along with tube 3. Until shoulder 11' engages ring flange 6 spring 7 holds pipe 3 against the well bottom. If flange 6' does not form a connection between the pipe and tube at this point then eventually shoulder 8 engages flange 4 of the safety ring 4 to lift pipe 3 along with it to the surface.
Thus it will be seen that as soon as the magnet 1 rises above the level of ring 6 in FIGURE 1, carrying with it the retrieved metal objects from the well bottom into the interior of pipe 3, iinger springs 5 automatically extend radially in across the pipe to effectively block it and prevent loss of the retrieved objects even if they should become dislodged from magnet 1.
The recovered metal parts are brought to the surface p are released from the magnet. Thus it is assured that the obstacle to drilling will be removed by lifting the rod only once.
The invention may be embodied in other speciiic forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
What is claimed and desired to be secured by United States Letters Patent is:
1. In a grappling mechanism for recovering loose metal objects from the bottom of a Well, a rod-supported member having a magnet on its lower end, a tubular shield having at least a part surrounding said magnet in spaced relation thereto, a shear element normally holding said magnet and shield in predetermined relative axial position wherein the magnet is disposed near the lower end of the shield in object retrieving position, said element being broken to permit relative axial displacement of the shield and magnet when the shield encounters the bottom of the well, resilient means biasing said shield axially relative to said magnet, and means actuated after predetermined lifting of the magnet relative to the shield for automatically effectively blockingthe lower end of the shield so that retrievedobjects will not be lost even when.
separated from said magnet.
2, In the mechanism defined in claim l, said resilient means being in the space between said memberand shield and reacting against said member and acting to normally urge said shield toward the well bottom, and means mov-` able with said magnet adapted to engage and lift the shield as the magnet is raised.
3. In the mechanism defined in claimY l, said` shield being a pipe surrounding themagnet, said means blocking the lower end of the shield being a plurality of spring' fingers normally retained against the bore of the pipe by an axially movable retainer, and coacting means on the retainer and magnet for releasing saidV spring lingers to project into the interior of saidpipe. after the magnet has been raised a predetermined amount.
4; ln the mechanism defined in claim 3, said retainer being a ring normally engaging free ends of said spring fingers, and cooperating axially engageable projections on the magnet and ring for moving said ring to release said spring fingers.
5. In a magnetic recovery device for retrieving objects from wells, a permanent magnet lowerable into the well, a protective shield surrounding said magnet and mounted for relative axial movement, a plurality of internal grappling springs within the lower end of said shield, means holding said springs in inactive position, and means operative after predetermined axial upward displacement of the magnet relative to said shield for releasing said springs to an active position extending into the interior of said-shield below the magnet, the lower end of said shield which mounts said springs being substantially nonmagnetic.
6. ln the device defined in claim 5, a rod supporting said magnet and said magnet being a rigid hollow extension of said rod.
7. In a magnetic recovery device for retrieving objects from the bottoms of wells, a magnet carried by the lower end of a rod, a relatively axially displaceable protective References Cited inthe tile of this patent UNITED STATES PATENTS 2,493,992 VMurphy et al. Ian. l0, 1950 2,522,294 Noble Sept. 12, 1950 2,539,435. Kirby Jan. 30, 1951 2,613,980 Hawkins Oct. 14, 1952 2,657,752 Ballew et al Nov. 3, 1953