US2890757A - Compliant coupling system for adapting sonic well drill apparatus to jarring function - Google Patents

Description

June 1 6, 1959 ODINE 2,890,757

A.G.B COMPLIANT COUPLING SYSTEM FOR ADAPTING SONIC WELL DRILL APPARATUS TO JARRING FUNCTION Filed 001;. 28, 1957 FIG. 3 FIG. 4 FIG. 1 26 FIG. 2 /2 $24 26- 20 A A 23 22 PK H /2| A 4 24 2s 2O ALBERT cs. BODINE ATTORNEY boMPLIANT COUPLING SYSTEM FOR ADAPTING SONIC WELL DRILL APPARATUS T JARRING FUNCTION Albert G. Bodine, Sherman Oaks, Calif. Application 0ctober'28, 1957, Serial No. 692,787

1 Claim. (Cl. 166-177) This invention comprises a compliant coupling system adapted to be located between a vibratory rod assembly normally comprising the motivating means for a sonic vibratory well drill bit and a grapple of the type used in oil well jars, whereby the sonic vibratory drill assembly may be used to perform the function of fishing or jarring loose any drill pipe or other dn'll tools which have become stuck in any hole or well in the earth, irrespective of the type of drilling operation resulting in the pipe or tool being stuck.

Anobject of the invention is accordingly to provide a simple means by which a sonic drill may be adapted to the purpose of occasional jarring operations.

A suitable sonic drill of the type contemplated by the invention is disclosed in my Patent No. 2,554,005, May 22, 1 951, and said patent is incorporated herein by reference, and the details thereof will not, therefore, require to be shown here. Such a drill, when in the field, has occasional unique usefulness, by a simple conversion", as a service tool in particular situations where pipe or tools have become stuck in a well. Such a drill comprises, essentially a massive longitudinally vibratory elastic rod string, usually a string of drill collars, a vibration generator for setting up the vibrations in the rod string, a motor for driving the vibration generator, and a bit screwed to the lower end of the rod string. The conversion of the present invention consists in replacing the bit by a coupling extension comprising a compliant string of light pipe, e.g., drill pipe, of a preferred length of approximately one quarter wave length. With respect to wave length, as disclosed in my aforesaid patent, the rod string may vibrate in a half-wave length standing wave mode, with a velocity antinode at each end, and a stress antinode at the mid-point. The coupling extension pipe, for this case, may then be half the length of the half wave length rod string. The lower end of the compliant coupling extension carries a means for grasping a fish, such as an overshot or spear.

In operation, the sonic drill vibration generator is caused to resonate the drill rod assembly in exactly the same manner as when driving the sonic drill bit. In this case, however, the sonic wave action is applied to the top end of the above-described compliant coupling pipe. The lower end of this compliant pipe will be understood to be coupled tightly to the upper end of the fish, which is stuck fast in the well hole. The compliant pipe accordingly becomes an acoustic lever, having a large cyclic elastic displacement amplitude where coupled to the vibrating drill rod string, and minimized displacement amplitude at the overshot or spear, i.e., where coupled to the stuck fish. The first or upper region is accordingly a point of relatively low impedance (low ratio of cyclic force to displacement), while the lower region, at the fish, is a relatively high impedance region (high ratio of cyclic force to displacement). High cyclic forces are thus applied to the fish" for loosening it from its stuck condition. The fish becomes a part of the acoustic circuit, and its contact surres Patent ice face at the stuck point in the well becomes a high impedance acoustic energy transmitter. By virtue of acoustic mismatch of impedance at the stuck interface, relative vibrations occur, with a resulting powerful loosening action. In addition, alternating waves of compression and tension, set up in the coupling pipe as a result of the driving action of the drill rod assembly, are propagated down the coupling pipe, and cause a dilational wave phenomenon in the fish, i.e., a sonic frequency fluctuation in circumference. Earthen structure cannot respond well at the sonic frequencies here involved,which are of the order of to c.p.s., and literally stand back dynamically from the stuck fish.

The invention will be further understood from the following detailed description of an illustrative embodiment thereof, reference for this purpose being had to the accompanying drawings, in which:

Figure 1 is a view, partly in elevation and partly in section, showing a typical installation of surface equipment for a sonic drill, and including the main portion of the drilling assembly proper;

Figure 2 is a view showing a portion of the sonic drilling assembly extending downward from the parts shown in Figure l;v

Figure 3 is a view showing the balance of the drilling assembly, and understood to extend downwardly from the parts shown in Figure 2, Figure 3 showing also the jarring accessory of the present invention; and

Figure 4 is a view, partly in elevation and partly in section, showing the jarring accessory of the present invention to larger scale, with an intermediate portion broken away, and showing the application of the accessory to a fish.

At the ground surface (Fig. 1) is a conventional derrick 10, draw works 11 driving rotary table 12, kelly 13, extending through table 12, swivel 14 coupled to the upper end of kelly 13, and hook 15 supporting the bar of swivel 14. Hook 15' is supported from above in the conventional manner. Mud fluid such as is conventionally used in rotary oil well drilling is delivered from con ventional equipment to pipe 16 and thence hose 17 to swivel 14, from which it flows down through kelly 13 to the drill pipe string 18. The pipe string 18 will be understood to be made up of a number of usual drill pipe lengths coupled together by usual tool joints such as indicated at 19.

The drilling assembly proper comprises, starting from the top, an elastic vibration generator assembly G including a motor unit 20, driven by the mud fluid circulated through the system, a mechanical vibrator 21, driven by said motor unit, and adapted to generate cyclic, vertically-directed force pulses, and a long interconnecting part 22. This vibration generator assembly is supported from drill string 18 by means of a relatively long and heavy sub 23 composed typically of a section of drill collar, together with a relatively short length of thinner walled pipe or casing 24. The drilling assembly proper further comprises an elongated elastic longitudinally vibratory rod 25, of very substantial mass and length, in this instance made up of three conventional collars 26 connected end to end by subs 27, this assembly of drill collars being coupled to the lower end of vibrator 21 by means of sub 28.

A sonic drill of the. type contemplated is completed by means of a bit (not here shown) coupled to the lower end of the lowermost of the drill collars 26, all as set forth in my said Patent #2,554-,005. The details of the component parts of such a sonic drill are fully set forth in the aforesaid patent and need not be repeated herein. Suifice it to say that in the operation of the sonic drill, the vibration generator assembly G causes cyclic vibration forces to be applied to the upper end of the drill rod or collar 25 at the frequency of a longitudinal resonant elastic vibration of said rod. Typically, the frequency is such as to cause the rod 25 to vibrate as a free-free bar in substantially a half wave length longitudinal standing wave mode, though the bar may also be operated in a full wave length mode or other modes, as set forth in my said earlier patent. The bit impacts against the foimation as a result of the vibration of the rod 25.

According to the present invention, in course of field operations with the sonic drill, upon encountering an occasional situation in which a tool or fish is lost and stuck in the well, the sonic drill is converted, by means of a simple accessory, to the function of grappling the fish and hence jarring it loose from its stuck condition. To this end, the sonic drill bit, not here shown, is uncoupled from the lower end of the rod string 25 made up of collars 26, and replaced by a compliant pipe 30, which may be a section of common drill pipe. The pipe 30 has a threaded coupling pin 31 at the top adapted to be screwed in to the threaded box 32 at the lower end of the lowermost collar 26. At its lower end, pipe 30 has a threaded coupling pin 33 threaded into the box 34 at the top of a somewhat diagrammatically shown grappling tool 35, which may be either an overshot, or spear, of any character desired, but is here shown in the form of an overshot embodying a tubular body having wedge slips 36 designed for engagement with the fish 37. As will be understood, the string of tools, with the pipe 30 and grappling tool 35 in place, is manipulated to seize the fish 37; and a tension may then be taken in the string of tools to assure that the fish is firmly held by the wedge slips.

Preferably, the pipe 30 is given a length approximately one quarter wave length of the wave pattern generated in the longitudinally vibratory rod string 25. Thus, if the rod string 25 receives force impulses at such frequency for its length as to vibrate in a half wave length (M 2) standing wave mode, as indicated in Figure 3, then the coupling pipe 30 may have a. length approximately equal to a quarter wave length (M4). The result, as diagrammed in Figure 3, is that the rod string 25, the coupling pipe 30, the grapple 35, and the fish 37 down to the stuck point, are all included in the acoustic circuit, and experience a substantially three-quarter wave length standing wave of the character represented at s when the apparatus is in operation.

Operation is as follows: The vibration generator, as in drilling, applies cyclic vibration forcesto the upper end of the drill rod 25 at a resonant frequency of the rod, causing a half wave length standing wave in the rod, as indicated in Figure 3. The lower end of the rod 25 vibrates against the upper end of the compliant coupling pipe 30. At the coupling point between heavy rod 25 and compliant coupling pipe 30, there exists a velocity antinode V, which is a region of relatively low impedance, characterized by a relatively low ratio of cyclic force to displacement amplitude. At the lower end of the coupling pipe 30, the acoustic system is held relatively firm by the rigid coupling to the fish, and stuck condition of the fish in the well bore. Here, accordingly, there exists a stress antinode region P, characterized by a relatively high ratio of cyclic force to displacement amplitude. The compliant coupling pipe 30 thus acts like an acoustic lever translating the relatively low cyclic force and high displacement amplitude at the coupling point between rod 25 and pipe 30 into relatively high cyclic force and low displacement amplitude at the grappling tool, and at the stuck point between the fish and the well bore. The fish becomes a part of the acoustic circuit, and transmits acoustic energy into the walls of the well bore. By virtue of the acoustic mismatch of impedance at the point of contact between the fish and the well bore, relative vibrations occur, which loosen the fish from the bore. Also, the alternating waves of compression and tension set up in the coupling pipe cause alternating dilations and contractions of the fish at sonic frequency and since the earths structure is incapable of following these closely, a further powerful loosening factor is introduced. The fish may be progressively loosened from the well bore in the downward direction; and in such case, the standing wave pattern along the coupling pipe 30 and fish, down to the stuck point, may progressively lengthen. This may have a tendency to lower the resonant frequency of the overall'system, and may cause a downward shift of the node N. But .because of the much heavier cross section of the rod as compared to the coupling pipe 30, this effect is small, and the standing wave pattern from the upper end of pipe to the stuck point can lengthen considerably without greatly influencing the portion of the standing wave pattern along the rod 25, or the overall resonant frequency.

The accessory provided by the invention thus enables a sonic drill of the character described to be employed occasionally to carry out easily and inexpensively a fishing and jarring problem encountered in the field.

I claim:

An apparatus for jarring and retrieving a fish which has become stuck in a well hole in the earth, comprising, in combination with a sonic earth boring apparatus that includes a string of drill collars having a bit coupling means at the lower end thereof, and a vibrator and drive motor therefor coupled to said string of drill collars for applying cyclic'longitudinal forces thereto at a resonant frequencythereof for a mode of longitudinal standing wave vibration, whereby a longitudinal standing wave is set up in said string of collars, and a velocity antinode of said standing wave appears at the lower end thereof: an elastically compliant coupler pipe having a coupling at its upper end for coupling to said bit coupling means at the lower end of said string of collars, said elastically compliant coupler pipe having a length approximately equal to a quarter wave length of said standing wave set up in said string of drill collars, and a grapple on the lower end of said quarter wave length compliant coupler pipe adapted for grappling and tightly engaging a fish which has become lost in a well bore, all in such manner that said longitudinal standing wave continues on down said coupler pipe, and said coupler pipe vibrates in sul'r stantially a quarter-wavelength standing wave mode, with a velocity antinode at its upper end, and a stress antinode in the general region of the grapple on its lower end in engagement with the fish," whereby the fish is vibrated with a high ratio of cyclic force to displacement amplitude as compared to a low ratio of cyclic force to displacement amplitude in the apparatus in the region of the coupling between the string of drill collars and said coupler pipe.

References Cited in the file of this patent UNITED STATES PATENTS

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