United States Patent 3722603

A fluid pressure-operated snubber device for use in drilling wells, generally in place of rotary table and drawworks systems commonly employed for rotary drilling. The device comprises a stationary lower snubbing member and rotatable and vertically reciprocable upper snubbing member operable for rotating drill pipe for drilling a well and for running the drill pipe into and out of the well. Each of the snubbing members includes a set of pipe-gripping wedges movable into and out of pipe-gripping engagement by fluid pressure-operated means and a set of cam actuated shoes for applying torsional forces to the pipe string for rotating the same in drilling and in making-up and breaking-out the sections of the pipe string when running into and out of the well.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
81/57.16, 81/57.18, 173/149, 173/164
International Classes:
E21B19/08; E21B19/10; E21B19/16; (IPC1-7): E21B19/16
Field of Search:
173/149,152,159,164 81
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US Patent References:

Primary Examiner:
Purser, Ernest R.
I claim

1. A well drilling snubber, comprising:

2. A well drilling snubber according to claim 1, wherein said fluid pressure-operated means comprises:

3. A well drilling snubber according to claim 2 including:

4. A well drilling snubber according to claim 1 wherein said torsion-transmitting member comprises:

5. A well drilling snubber according to claim 1, including: a cam sleeve connected to said means for reciprocating said wedges and forming a rotatable connection between said bushing and said body operable in response to movement of said wedges to pipe-releasing position to move said pipe-gripping member out of pipe-engaging position.


In conventional rotary drilling, a power-driven rotary table operating through a so-called "Kelley joint" connected to the upper end of the drill pipe string is employed for rotating the drill string and high-powered drawworks systems, including derricks with multiple-strand, cable-connected crown and travelling blocks, are employed for running the drill string into and out of the well and for otherwise performing drilling and pipe handling operations. Conventionally, the rotary table and the drawworks and the power units for driving and operating the same constitute massive, relatively complicated and expensive structures, particularly those designed for deep drilling.

The present invention is directed to a relatively simple, compact structure comprising fluid pressure-operated, preferably hydraulic, elements for performing both the drilling and pipe-running functions of more conventional rotary rigs.

In accordance with the present invention, an improved form of hydraulic snubbing device is provided comprising a stationary lower snubbing member or head and an upper snubbing member or head which is both vertically reciprocable and rotatable relative to the lower head, the snubbing heads cooperating with a pipe string to perform the rotary drilling functions and the running of the pipe string into and out of the well. Each of the snubbing heads includes sets of vertically reciprocable pipe-gripping wedges or slips and angularly rockable, cam-actuated gripping shoes for applying torsional forces to the pipe string for use both in rotating the pipe string for drilling and when making and breaking the threaded pipe joints as when adding joints to the drilling string and when running the string into and out of the well.

All the principal elements of the device are designed for fluid pressure, preferably hydraulic pressure, operation.

The structure in accordance with this invention is thus very compact, low in cost, easily transportable, simple in operation, and readily adaptable for drilling to any desired depth. The structure requires only a relatively simple, low capacity derrick or mast in conjunction therewith, since the major functions of such derrick or mast will be to support relatively low weight elements such as the mud swivel and hose and at most, only a few sections of pipe, since the main load of the pipe string both in drilling and in running into and out of the well will be taken by the snubber heads, as will appear hereinafter.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates one useful embodiment in accordance with this invention.

In the drawing:

FIG. 1 is a view partly in elevation and partly in section of the snubber device showing the upper snubbing member in gripping engagement with the drilling string and the lower snubbing member in released position;

FIG. 2 is a view similar to FIG. 1 but showing both snubbing members in gripping engagement with the drilling string;

FIGS. 3 and 4 are cross-sectional views taken respectively on lines 3--3 and 4--4 of FIG. 1;

FIGS. 5, 6 and 7 are cross-sectional views taken respectively on lines 5--5, 6--6 and 7--7 of FIG. 2;

FIG. 8 is a detail view taken on line 8--8 of FIG. 1;

FIG. 9 is a cross-sectional view taken on line 9--9 of FIG. 1; and

FIG. 10 is a cross-sectional view taken on line 10--10 of FIG. 1.

Referring to the drawing, the snubber device is shown mounted on a base plate 10 which is generally U-shaped (FIG. 9) and is ordinarily appropriately mounted on a longitudinally slotted skid S enabling the structure to be moved laterally into place about the upper end of a well W. A plurality of hydraulic jacks, designated generally by the letters J, four in number in the illustrative embodiment, are mounted in upright position on base plate 10 and spaced to define the corners of a square. Each of the jacks comprises a cylinder 11 and a suitably sealed piston 12 slidably mounted for reciprocation in the cylinders between pressure fluid connections 13 and 14 which serve alternately as inlet and discharge conduits for the pressure fluid employed for reciprocating the pistons. The pistons are connected to elongate piston rods 15 which extend upwardly through stuffing boxes 16. The upper ends of the piston rods are suitably connected to a transverse crosshead plate 17 which supports an upper snubbing head, designated generally by the letter H1, for vertical reciprocating with the crosshead plate.

A lower crosshead plate 18 extends transversely between the cylinders 11 at a suitable elevation above base plate 10 and is fixedly secured to the cylinders. Crosshead plate 18 supports a stationary lower snubbing head, designated generally by the letter H2.

A top plate 19 is supported above crosshead plate 17 on the upper end of a ring-shaped wall 20 which is seated about a peripheral shoulder 21 on plate 17 and has its upper end secured by bolts 22 to the rim of top plate 19.

The snubbing heads H1 and H2 are generally similar in construction, the same or corresponding parts bearing the same numerals. Snubbing head H1 includes additional structure for positively rotating the same and the parts therefor will be appropriately designated as the description proceeds.

Each snubbing head comprises a tubular housing 23 carrying on its lower end an off-set flange 24 which is received in the upper end of a housing extension 23a and secured thereto by bolts 24a. In the case of upper snubbing head H1, the housing is mounted for rotation in coaxial openings 25 and 26 in top plates 19 and in crosshead plate 17, respectively. In the case of lower snubbing head H2, the housing extends through a central opening 27a in lower crosshead plate 18 and is fixedly secured thereto by means of a bolted flange 28. A rotary bushing 29, having a downwardly and inwardly tapering frusto-conical bore 30, is mounted in housing 23 for relative rotation on bearings 27 and is provided about its exterior with an annular groove 31 adapted to receive the inner ends of guide pins 32 (FIG. 5) which are screwed through the wall of housing 23 to effectively guide relative rotation between the latter and bushing 29. The lower end of the latter carries a downwardly extending annular flange 33 keyed to a cooperating upwardly extending annular flange 34, which is secured to an annular cam plate 35 disposed concentrically inside housing extension 23a to define a generally annular space 35a therebetween. Cam plate 35 has a central bore 36 and a plurality of equi-angularly spaced slots 37 (four illustrated as in FIG. 4) extending radially entirely through the plate.

A shoe 38, generally rectangular in cross-section, is slidably mounted in each slot 37 for limited radial movement therein and carries a series of cam rollers 39 rollably mounted about a vertical shaft 40 supported from the inner or rearward end of shoe 38 to project into annular space 35a. The opposite ends of shaft 40 extend above and below rollers 39 into annular space 35a and carry small rollers 41 which limit outer or forward movement of shoe 38 by engagement of rollers 41 with the inner periphery of plate 35. The outer end of each shoe 38 has mounted therein a plurality of vertically extending pipe-gripping teeth or dies 42.

The inner wall of housing extension 23a is formed with a plurality of inwardly projecting drive cams 43 (FIGS. 4 and 6), spaced on 90° centers by relief grooves 44. The cams cooperate with rollers 39 in response to relative angular rotation between plate 35 and housing 23, 23a to advance or project shoes 38 inwardly of bore 36 and to allow retraction of the shoes when rollers 39 move off of cams 43 into relief grooves 44.

As best seen in FIGS. 1 and 10, each snubbing head is provided with a second set of angularly spaced cams 45 which project from the inner periphery of cam plate 35 adjacent its upper and lower edges in alignment with the roller-carrying ends of shafts 40. These cams also are on 90° spacing and are offset 45° relative to cams 43 and engagement with rollers 41 to effect positive retraction of shoes 38 from pipe-gripping position at certain stages of operation, as will appear subsequently.

Both of the snubbing heads H1 and H2 are fitted with generally similar power-operated slip lifter devices, designated generally by the numerals 50. Each of the latter comprises a downwardly and inwardly tapering frusto-conical slip bowl 51 seated in bore 30 of rotary bushing 29 and secured thereto through an overhanging bolt flange 52 by means of bolts 53. A plurality of pipe-gripping wedges or slips 54 are longitudinally slidably mounted in slip bowl 51 and keyed thereto by longitudinally extending dove-tail keys 55, as best seen in FIGS. 3 and 5. The upper ends of the slips carry hanger arms 56 which project through pockets 57a in a hanger ring 57 and are slidably supported for limited angular movement on the upper edges of the hanger ring pockets by means of hanger bolts 56a. Hanger ring 57 is mounted for rotation in an overhanging lift ring by means of bearing-supported trunnions 58a. The lift ring is secured to the upper ends of pistons 59 mounted in cylinders 60 for reciprocation in response to fluid pressure supplied to the cylinders through spaced apart pressure fluid conduits 61,61 which serve alternately as supply and exhaust conduits in the known manner.

Returning now to the afore-mentioned additional structure for effecting positive rotation of snubbing head H1, housing 23 of the latter is provided opposite off-set flange 24 with an outwardly extending annular flange 65 which is suitably connected by bolts 66 to the hub 67 of a ring gear 68 positioned horizontally in the space between top plate 19 and upper crosshead plate 17 and supported for rotation on bearings 69 between the latter and flange 65 and bearings 70 disposed above flange 65 between housing 23 and the bore 71 of top plate 19. A plurality of reversible hydraulic motors 72 are mounted on top plate 19 with their shafts 73 extending downwardly through the top plate and carrying pinions 74 which are in mesh with teeth 75 of ring gear 68 for effecting reversible rotation of upper snubbing head H1. Motors 72 are connected by conduits 76 and 77 to pressure fluid supply and exhaust manifolds 78 and 79 which are, in turn, connected by conduits 80 and 80a to suitable pressure fluid supply and discharge sources.

In connection with the operation of the slips 54 and shoes 38, each of the snubbing heads is provided with a cam sleeve 81 pendently secured to hanger ring 57 and having an internal diameter to closely surround the exterior of housing 23 and so as to be slidable over and about the latter. Cam sleeve 81 is provided on opposite sides thereof with windows 82 shaped, as best seen in FIG. 8, with opposed downwardly sloping cam surfaces 83,83 terminating in spaced relation to provide a vertical slot 84 therebetween which opens to the lower edge of the sleeve. The cam sleeve cooperates with rollers 85 mounted on headed shafts 86 extending radially outwardly from housing 23 adjacent its upper end. The lower edge of sleeve 81 carries an outwardly extending annular flange 87 provided with vertical openings 88 to allow passage of rollers 85 therethrough as may be required during operation of the device, as will be described hereinafter.

In operation, FIG. 1 illustrates the positions of the parts at the beginning of a drilling-ahead sequence. It will be noted that slips 54 in upper snubbing head H1 are in the lowered or set position gripping drill pipe P which extends through both snubbing heads into well bore W, and the slips in lower head H2 are raised and retracted in completely inactive position so far as drilling is concerned. Also upper head H1 will be in its elevated position as determined by the upward extension of piston rods 15 from cylinders 11 of jacks J. Lowering of upper slips 54 will simultaneously lower its attached cam sleeve 81 producing relative upward movement of rollers 85 through slots 84 to inactive or neutral center positions in windows 82 indicated at 85a, as seen in FIG. 8.

Initiation of rotation of housing 23, 23a of the upper head by motors 72 will produce an initial angular movement of the housing relative to cam plate 35 which will move drive cams 43 behind rollers 39 to project shoes 38 inwardly to force dies 42 into torsion-applying pipe-gripping position, whereupon continued rotation of the upper head by the hydraulic motors will rotate the drill pipe. At the same time, fluid pressure may be directed to jacks J to control "weight-on-bit" to any extent desired to assure optimum drilling rate and to allow downward movement of the upper snubbing head to conform with the advance of the drill.

It will be understood, although not shown, that drilling fluids may be circulated down through the drill pipe and bit and up through the well bore in a conventional manner as the drilling proceeds to perform the functions ordinarily required of such fluid.

As slips 54 in lower head H2 are raised to release their grip on the drill pipe, the associated cam sleeve 81, being attached to lift ring 57, will be moved upward relative to lower housing 23, 23a. Teeth 42 of shoes 38 in the lower head H2 will still be in engagement with the drill pipe. However, by reason of this engagement, initial angular movement by the upper snubbing head will be transmitted through the drill pipe to cam plate 35 in the lower snubbing head causing the cam plate to rotate retractor cams 45 into engagement with the roller carrying ends of the related shaft 40 (FIG. 10) to effect positive retraction of shoes 38 from engagement with pipe P thereby freeing the pipe for rotation by the upper snubbing head.

When the end of a drilling stroke is reached, and it is necessary to add a new section of drill pipe, the slips in the lower head will be set below the drill pipe box B, in the position as seen in FIG. 2 and the mud line connection to the upper end of the drill pipe will be released. Thereupon the upper set of slips will be raised and released and the upper snubbing head raised to receive the new section of drill pipe which will be lowered through the bore of the upper snubbing head and its threaded pin stabbed into the box member of a coupling C. Thereupon, the upper slips will be lowered and set and right-hand rotation of the upper head begun while the slips in the lower head remain in gripping position to serve as a back-up wrench while the threading operation takes place. Some pressure fluid may be released from jacks J to accomodate the downward movement of the upper head as the threads are made up. The setting of the upper slips and the initial rotation of the upper head will act through upper cams 43 to move upper shoes 38 into torque-applying engagement with the pipe.

This sequence of operations as heretofore described is repeated as the drilling proceeds to continue the addition of sections of pipe to the drilling string to correspond to the increased well depth.

FIG. 2 also illustrates the relative positions of the snubbing heads at a stage in the process of breaking down the pipe string, as when withdrawing it from the well for changing bit or other purposes requiring removal of the pipe from the well. As shown, both sets of slips 54 and torque shoes 38 will be set to grip the pipe on opposite sides of coupling C. Thereupon, upper head H1 may be rotated in the direction to unscrew the upper section of the pipe string while the lower head H2 holds back against the lower pipe section. Pressure fluid will be applied to jacks J to raise upper head H1 sufficiently to accommodate the unthreading operation. The upper slips may then be released to allow the now unthreaded pipe section to be withdrawn from the upper head.

The upper head will then be lowered about the upper end of the pipe section left projecting above the lower head and the upper slips will again be set; the lower slips released and the pipe string raised to bring the next coupling up above the lower head in position for repetition of the previously described unscrewing of the thus elevated pipe section.

Elevation of cam sleeves 81 with their respective lift rings 57 in effecting release of the related slips 54 will produce camming action between cam surfaces 83 and rollers 85 to produce the limited relative angular movement of cam plate 35 required to cause retractor cams 45, by acting against the ends of shafts 40, to effect retraction of shoes 38 sufficient to retract teeth 42 from engagement with pipe P. This provides assurance that any time slips 54 are released, the torsion-applying teeth 42 also will be positively released.

The well drilling apparatus heretofore described provides a highly efficient, low-cost, rotary drilling unit capable of drilling to depths of 10,000 feet or more by reason of the fact that the entire load of the drilling string in drilling and in running the pipe in and out of the well is carried on hydraulic jacks. Thus, only a light load capacity derrick or mast is required as the maximum loads to which they may be subjected will be the weight of a joint or stand of pipe and the mud hose and swivel. The need for conventional massive crown and travelling blocks and Kelley joints is likewise eliminated.

Also, since the jacks are operated by hydraulic pressure, the power requirements for running and operating the drill string may be met by relatively small compact power units as compared with the engines required for more conventional rotary drilling rigs. The whole rig may be skid-mounted for easy overland transportation by trucks and is readily adaptable for use in marine drilling.

The apparatus herein described may also be used for running casing, when required, by appropriate changes in the dimensions of the pipe-gripping elements to accommodate the different casing dimensions.

The entire system for drilling and handling pipe is designed for operation by a set of remote automated controls; requires an absolute minimum of manual labor; and operates with a maximum degree of speed and efficiency.

The numerous other advantages of the apparatus herein disclosed will be readily apparent to those skilled in the art. It will be understood that numerous changes and modifications may be made in the details of the illustrative embodiment within the scope of the appended claims but without departing from the spirit of this invention.