US2976930A - Drill pipe shock absorber - Google Patents

Description

March 28, 1961 D. E. MARQUIS ET AL 2,976,930

DRILL PIPE SHOCK ABSORBER Filed Aug. 1, 1958 ACCUMULATOR INVENTORS D.E. MARQUIS G.F. H W

u if? MILLER BY .PATTERSON MM W 6- 5O TON JACKS FIG. 2

A TTORNE KS DRILL PIPE SHOCK ABSORBER Duane E. Marquis, Bartlesville, Okla., Glenn F. Miller, Odessa, Tern, and Hugh W. Patterson, Bartlesville, Okla, assignors to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 1, 1958, Ser. No. 752,523

8 Claims. (Cl. 166-85) This invention relates to-well drilling. -In one aspect this invention relates to an apparatus for absorbing or cushioning shock incident to handling drill pipe within a bore hole.

In the drilling of a bore hole or well such as a gas or oil well, it is frequently necessary to lower into and withdraw from the hole rods or tubing, generally referred to hereinafter as drill pipe, which support bits or other drilling devices. The withdrawing and replacement of such drill pipe are necessary, for example, to change bits or other purposes. It is known in the art to use elevators, slips and the like to support the string of the drill pipe during such operations. The drill pipe, when in use, is frequently rotated by means of a kelly and a rotary table. When the string is lowered onto the table, the table is subject to impacts of enormous amounts when the string is brought to rest, since these strings are fre quently several thousands of feet long and of great weight. These impacts may be so great as to fracture the drill pipe or to damage the rotary table. In wells of 10,000- l5,000 feet or less, the tubes are generally prepared of relatively soft steel and slips are generally employed for supporting the weight of such strings since slips are readily placed and removed from the tubes. Although slips tend to bite into the surface of the steel drill pipe, this is not unduly harmful with the soft steel. In deep wells, e.g. over 10,000 to 15,000 feet in depth, the first 10,000 to 15,000 feet is frequently of soft steel and over this depth high tensile steel drill pipe is added to the string. However, since slips tend to notch the pipe they are not desirable for use on the harder high tensile steel pipe which has much greater notch sensitivity. Such pipes when notched, have a tendency to fail as the result of such notches. Therefore, with such drill pipe, elevators are preferred for handling same. Since elevators have no cushioning effect when the weight of the drill string is placed on the rotary table it is desirable to provide some cushioning means. When removing strings from bore hole, the string is raised a section length, a slip or elevator placed around the string, the string supported on the rotary table and the top section removed from the string. This process is continued until all of the string is removed. In lowering the string, the process is reversed, a section at a time being added.

:It is an object of this invention to provide means for minimizing damage due to handling tool strings when placing or measuring same from a drill hole.

Other objects, features and advantages of this invention will be obvious to one skilled in the art having been given this disclosure.

The apparatus of this invention comprises a plate adapted to slip under a string lifting means and supported on a plurality of hydraulic jack-s connected through metering means to a common gas cushioned liquid accumulator.

The apparatus of this invention is broadly operable for handling bore strings generally and is particularly de- States Patent sir-able for use in conjunction with an elveator on strings of 15,000 feet in length or over.

This invention will be further described in conjunction with the attached figures of which: 1

Figure l is an elevation of a preferred embodiment of the apparatus of this invention; and

Figure 2 is a schematic showing of the piping arrangement of this invention.

Referring now to the drawings, plate 1 has a cylindrical riser 2 to fit around a well string and having slot 3 therein so that the entire apparatus can be slipped around the string. A plurality of guide cylinders 4 (four in the drawing) are provided for holding the top plate 17 in place. Also supported on plate 1 are a plurality of hydraulic jacks 5 (six in this embodiment) spaced on support plate 1 to'distribute the load applied to the top plate equally. These jacks 5 are operably connected to accumulator 12 via conduits 6, 7 needle valve 8 and conduit 9. Needle valve 8 is by-passed with conduit 10 and check valve 11 which permits free flow of fluids from accumulator 12 toward jacks 5, but prevents flow in the opposite direction. Pressure'release valve 13 is provided between the jacks 5 and the check valve 11 and needle valve 8 as a safety means should the shock applied to the jacks become too great for the hydraulic system. As shown, this check valve releases into the center of the riser 2. Pressure gage 14 is operably installed through needle valve 15 in the conduit between the jacks and valves 8 and 11. Rods 16 are provided for securing the cover plate to the shock absorbing as sembly.

Cover plate 17 is provided with a plurality of studs 18 matched to the cylinders 4 on the base plate 1. This plate is provided with a cut-away 19 to fit around the string. It is within the scope of this invention to provide a shield or metal plate extending downward from the circular portion of slot 19 to fit inside the correspond-I ing portion of riser 2. This shield prevents mud and the like from running from the drill pipe into the apparatus. A cover plate can be provided for the rest of keyway 19 and this cover platecan also be provided with metal shields extending downward toward the base plate. It is alsowithin the scope of this invention to provide a skirt around the outer circumference of the assemblypreferably attached to and depending from the top plate.

Cover plate 17 is also provided with drilled and tapped holes 20 into which pins 16 are threaded. Pins 16 extend downwardly through drilled holes in lugs or brackets 21 and have locking nuts 22 on their lower ends. Thus, upper plate 17 is permitted to move downwardly but is prevented from moving upwardly a distance greater than that permitted by the free length of pins 16. Pins 16 also prevent the top plate 17 from being removed from the assembly as might occur if the entire assembly were picked up by the top 'plate. In general, the locking nuts 22 will be tightened at least sufiiciently to hold the cover plate 17 firmly against the jacks 5 and preferably sufiicient to depress the jacks a short distance, less than an inch, e.g., one-half inch.

The accumulator 12 can be of any conventional design and is so constructed that liquid flows through conduit 9 from the jacks into the accumulator and the liquid is cushioned by compressing a gas. In the particular embodiment, the liquid and gas phase is separated by a piston; however, a diaphragm or other separating means can be used, e.g., liquid gas interface.

The cut-away 19 in cover plate 17 can be the same or different from that of the base plate. For example, the same base assembly can be used on a variety of strings of different diameters by providing a plurality of cover plates keyed to fit difierent size strings. I While the drawing shows six jacks 5, four pins 16 and 3 four cylinders 4 on the base plate, these can vary as desired depending upon the total load and jack capacity, etc. It is desirable to have at least three jacks so that the load can be stabilized on the base plate 1 and at least two aligning cylinders 4 and studs 18 to keep the top plate aligned with the shock assembly. The pins 16 are optional, but are desirable in order to keep the top plate fastened tight against the supporting jacks. The safety valve 13 and gage 14 are optional equipment that will generally be employed for reasons of safety and convenience. Check valve 11 is an optional piece of equipment which permits better operation of the accumulator and jacks when the load is suddenly removed. Needle valves 15 and 8 can be replaced by any suitable means such as an orifice or small pipe to regulate the flow of liquid from the jacks in the accumulator and prevents the effect of a hydraulic hammer on the accumulator when load is suddenly applied. The needle valves are advantageously employed since they provide a ready and easily adjustable metering means.

In using the apparatus of this invention the drilling string is raised and lowered by conventional hoisting equipment common to all present day drilling rigs of the rotary type. Since it has been found that the slips customarily used to engage the pipe for supporting it from the rotary table are undesirable, a sequence of operation using two sets of elevators will be described. Assuming that drilling has been in progress, the drill string is raised by means of the hoisting equipment (draw works) and the shock absorber placed in position around the drill pipe. An elevator can then be placed around the drill pipe and the entire drill string lowered till the first threaded connection (tool joint) rests on the elevator. The Kelly joint is then broken off and placed to one side. The elevator is then attached to the traveling blocks by means of balls and the entire string hoisted to the desired height-usually 3 lengths of drill pipe or about 90 feet. At this point another threaded connector (tool joint) will have been raised above the shock absorber and a second elevator is installed between the top plate of the shock absorber and the tool joint. As the string is lowered, the weight of the drill pipe will come to rest on the elevator and this in turn will transfer the weight to the shock absorber. As the additional weight is imposed on the shock absorber the top plate will move downwardly and there will be increasing resistance to movement. Thus the shock absorber will bring the pipe to a cushioned stop and prevent sudden shock loads. The

lengths of drill pipe just above the tool joint resting on the shock absorber can now be unscrewed and set off to one side in the derrick. The first elevator is disengaged from the upper end of this length of pipe and is lowered to the derrick floor. The elevator bails are then transferred to the second elevator which now is suspending the drill pipe and the process repeated until all drill pipe is out of the hole. Drill pipe can be run back in the well by using the reverse of the above described process.

The advantages of this device are many. First, the shock absorber of this invention offers increasing resistance with increasing displacement thereby providing a smooth cushioning efiect. The absorber of this invention is readily installed on the drill string by means of the keyways or cut-away.

A shock absorber constructed as shown in Figure 1 utilizing 2 inch plate for the base and cover plates, six ton jacks, and a Parker Hydraulic Accumulator was used for lowering pipe into a well in excess of 15,000 feet. The four pins used for securing the top plate of the lower assembly were 1 inch in diameter and the guide studs and cylinder were of 5 inch diameter. In lowering 270,000 pounds of string, the device cushioned the drill string to a stop during 4 inches of travel by metering the fluid flow from the six pistons arranged in a circle through needle valves to the nitrogen charged piston type accumulator.

can be made and still obtain the advantages of this invention.

While we have described our invention for use in handling drill pipe in a well being drilled, it is of course obvious that the apparatus can be used with equal results in handling any other long string of steel goods such as well casing, well tubing or slicker rods.

While the preferred embodiment of the invention is described through the use of two sets of elevators, it is entirely feasible to use the shock absorber in the conventional manner with one set of elevators and a set of slips. It will be readily understood by one skilled in the art that the shock absorber could have a slip receiving bowl attached to the top plate of the assembly. This bowl could be removably installed above the top sur-- face of the top plate of the shock absorber or could be recessed in the top plate. While the use of slips would not entirely eliminate the possibility of damage to the drill pipe, the shock absorber would still provide protection against sudden shock loads and thus would afford an overall system superior to that in common industry use.

We claim:

1. An apparatus for absorbing shocks from a well string being moved within a bore hole comprising, in combination, a base plate provided with a central opening for said string, a cover plate provided with a central opening for said string, and hydraulic shock absorbing means between said plates comprising cylinder and piston assemblies, said assemblies being operably connected to hydraulic accumulator means to receive hydraulic fiuid from said assemblies when a load is applied to said cover plate.

2. Apparatus according to claim 1 wherein aligned slots extend from the central opening to the edge of each of said plates so that said apparatus can be centered on said string from the side thereof.

3. An apparatus for absorbing shock from a well string being moved vertically within a bore hole comprising, in. combination, a base plate provided with a central opening for said string, a plurality of hydraulic cylinder and piston assemblies mounted on said base plate in spaced relationship, a common hydraulic accumulator operably connected to said assemblies through a valved conduit, a cover plate provided with a central opening for said string resting on said assemblies, said cover plate being adapted to support said string, guide means connecte to said cover plate to align said cover plate on said assemblies, and a slot in each said plate extending from the central opening to the edge of the plate, said slots being aligned so that said apparatus can be centered on said string from the side thereof.

4. Apparatus according to claim 3 wherein there are at least three hydraulic cylinder and piston assemblies.

5. Apparatus according to claim 4 wherein the valve in said valved conduit is a needle valve.

6. An assembled apparatus for absorbing shock from a well string being moved vertically within a bore hole comprising, in combination, a base plate provided with a central opening for said string, at least three hydraulic cylinder and piston assemblies anranged in spaced rela tionship in a ring on said base plate and secured thereto, a hydraulic accumulator mounted on said base plate operably connected to said assemblies by a first valved conduit, said accumulator being also adapted to accumulate hydraulic fiuid against a gas cushion, a second valved conduit connecting said assemblies with said ac cumulator adapted to permit fluid flow from said accumulator to said assemblies, a cover plate provided with a central opening for said string resting on said assemblies. said cover plate being adapted to receive the weight of said well string, sleeved guide means connected to said plates to align said cover on said assemblies, securing means connected to said plates to prevent said cover from moving away from said base plate beyond a pre Those skilled in the art will see many changes which deter-mined distance upon removal of a load from said cover plate, and a slot in each said plate extending from said opening to the edge of the plate, said slots being aligned so that said assembled apparatus can be centered on said string from the side thereof.

7. Apparatus according to claim 6 wherein the valve 5 1503131 Nelson July 1,517,979 Greathouse Dec. 2, in said first conduit 1s a needle valve and the valve 111 1966 454 M d J l 17 1934 said second conduit is a check valve. 0057 Y y 8. Apparatus-according to claim 7 wherein a pressure 7 err relief valve is provided between said needle valve and 2,300,162 Maude said assemblies, said pressure relief valve being set at a 10 2,756,989 PeTas July predetermined maximum pressure.

References Cited in the file of this patent UNITED STATES PATENTS

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