Rotary Drive Connection For Casing Drilling String

Abstract

A drive connection for connecting a rotary power source to a string of well casing employed as a rotary drilling string. The drive connection is designed to be insertible in the upper end of the casing and is provided with a mandrel carrying slips and a slip expander for gripping the interior of the casing and pipe-gripping shoes operable in response to angular movement of the mandrel to apply torsional force to the casing.

Parent Case Text

RELATED APPLICATION

This application is a continuation-in-part of my co-pending U. S. Pat. application Ser. No. 778,509, filed Nov. 25, 1968, now U.S. Pat. No. 3,552,507.

Description

BACKGROUND OF THE INVENTION

In the afore-mentioned application, there is disclosed a rotary well drilling system employing relatively large diameter casing as the drilling string and a bit assembly adapted to be bodily inserted and withdrawn through the bore of the casing, being releasably connectible to the lower end of the casing for rotation thereby. Rotation of the casing string and the bit assembly is effected by means of a rotary power source suspended in the derrick and having a novel form of rotary drive connection to the upper end of the casing string.

SUMMARY OF THE INVENTION

The present invention is directed to the novel rotary drive connection itself. The latter, in accordance with an illustrative embodiment, comprises a tubular mandrel connectible to the drive swivel of the power source and insertible into the bore of the casing. The mandrel carries a set of wedge-shaped pipe gripping slips mounted for radial movement into and out of gripping engagement with the casing and an expander threadedly mounted on the mandrel for longitudinal movement into and out of wedging engagement with the slips in response to relative rotation of the mandrel. Also carried by the mandrel below the slips is a set of rockably mounted pipe-gripping shoes, operable in response to angular movement of the mandrel to apply torsional force to the casing in response to rotation of the mandrel so as to rotationally drive the casing.

This drive connection provides a very simple and effective means for releasably connecting the power source to the casing drill string, as when adding to or removing sections therefrom, or when inserting or receiving the bit assembly.

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 a useful embodiment in accordance with this invention.

In the drawing:

FIG. 1 is a longitudinal, partly sectional view of the drive connection shown inserted in the upper end of a casing drilling string and connected to a rotary power unit;

FIG. 2 is a longitudinal, partly sectional view of the drive connection showing the parts in their retracted non-driving relation to the casing;

FIG. 3 is a view similar to FIG. 2 showing the parts in the casing drive relation;

FIG. 4 is a cross-sectional view taken on line 4--4 of FIG. 2 showing the parts of the torsional drive elements in their non-driving position, and

FIG. 5 is a view similar to FIG. 4 showing the torsional drive elements in their drive position.

Referring to the drawing, FIG. 1 shows the drive connection assembly, designated generally by the numeral 10, inserted into the upper end of a string of casing C which is to function as the rotary drill string and extends into the upper end of well W lined with a conductor pipe K surmounted by a wellhead fitting F which includes a conventional slip bowl H adapted to receive hanger slips G (shown in broken lines) for supporting the casing string at appropriate stages of operation.

Drive connector assembly 10 includes a tubular mandrel or support member 11 having an axial bore 12 and provided with a threaded box 13 at its upper end for connection to a power source. A tubular bushing 14 is rotatably mounted about the upper portion of the mandrel on anti-friction bearings 15 and has a radially extending flange 16 dimensioned to rest on the upper end of the uppermost section of casing C which will normally project upwardly above the upper end of the well bore. Flange 16 forms stop means engageable with the upper end of the casing section to limit inward movement of the connection assembly into the bore of the casing. The inner end of bushing 14 carries an inwardly turned lip 17 on which a plurality of pipe-gripping wedges or slips 18 are hingedly supported by means of outwardly projecting hanger lips 19 formed on the upper ends of the slips. An upwardly and inwardly tapering conical expander 20 is disposed about mandrel 11 between the latter and slips 18 and is provided internally with a section of relatively coarse right-hand threads 21 engageable by a complementary section of threads 22 formed on mandrel 11 intermediate the ends thereof. With this right-hand threaded connection between the expander and the mandrel it will be seen that right-hand rotation of the mandrel will cause expander 20 to move upwardly relative to slips 18, the complementary tapered surfaces thereof cooperating to move the slips outwardly into gripping engagement with the wall of casing C. Reverse rotation of the mandrel will move the expander downwardly to release the slips from gripping engagement with the casing.

The lower portion of expander 20 is provided with an annular outwardly opening recess 23 defined by a cylindrical bottom wall 24 and at its outer end by oppositely extending annular lips 25--25.

Pipe-engaging elements, designated generally by the numeral 26, are mounted in recess 23 and are operable in response to angular movement of the mandrel to apply torsional force to the casing. This form of the gripping elements 26 is described in detail in my U. S. Pat. No. 3,322,006, issued May 30, 1967, and constitute casing-gripping means which are non-threadedly engageable with the casing for transmitting rotational torque thereto. While the specific details of these casing-gripping elements do not form a part of the present invention in view of the earlier patent thereon, a brief description will be helpful in connection with the present disclosure.

Mounted within recess 23 concentrically with bottom wall 24 is a pair of generally semi-circular pipe-gripping shoes 27 which are normally urged apart radially by means of relatively light coil springs 28 seated in suitable sockets 29 in the opposed ends of the shoes, as best seen in FIGS. 4 and 5, the spacing between the inner ends of the shoes permitting a limited amount of independent movement of the shoes. The upper and lower end edges of the shoes are provided with oppositely extending upper and lower flanges 30--30 which are adapted to engage lips 25--25, whereby the latter will prevent the shoes from being radially expelled from recess 23. Each of the shoes is provided centrally on its external surface with a longitudinally extending convex, generally smooth arcuate surface portion 31, which has a circular radius adapted to provide smooth or non-gripping engagement with the inner wall of a surrounding pipe, such as well casing C. Surface portion 31 extends for a relatively short angular distance about the outer periphery of the shoes. On each side of surface portion 31 the exterior of the shoes is off-set slightly radially inwardly at 32 and these radially off-set portions are provided with a few parallel, longitudinally extending, radially projecting teeth 33, which are normally out of contact with casing C when portion 31 is engaged with the casing wall. The teeth 33 are adapted, upon relative rotation or oscillation between the shoes and casing C, to engage the casing and prevent further relative rotation between the shoes and the casing, and to then apply a strong torsional force to the casing in response to rotational force transmitted from the expander body to the shoes. By reason of the longitudinally extending form of the teeth, some longitudinal slippage between the teeth and the casing can occur, even though the torsional force will prevent relative rotation between the teeth and the casing, as will appear subsequently. To effect relative rotation or rocking movement of the shoes, bottom wall 24 is machined to provide oppositely radially extending lugs 34, the lugs on opposite sides of recess 23 having openings 35 through which a cylindrical shaft 36 extends. A series of rollers 37 are mounted on each shaft 36 on opposite sides of the lugs 34 and constitute cam followers, the sets of the cam followers thus being mounted on diametrically opposite sides of recess 23. The inner periphery of shoes 27 on each side of the central portion thereof is provided with non-circular cam surfaces 38 which are engageable by cam followers 37 in response to relative angular movement between expander 20 and the shoes. As best seen in FIG. 5, cam surfaces 38 are shown engaged with cooperating cams 37 to rock shoes 27 angularly relative to casing C, so as to project teeth 33 into torsional gripping engagement with the wall of casing C.

The lower end portion of expander 20 is provided about the exterior thereof below recess 23 with an annular seal element 39 arranged for slidable sealing engagement with casing C and an internal annular seal element 40 arranged for slidable sealing engagement with the exterior of mandrel 11. Upper and lower stop collars 41 and 42, respectively, are mounted about mandrel 11 above and below the ends of the connector assembly to limit the extent of relative longitudinal movement between the mandrel and the other parts of the assembly.

Mandrel 11 is adapted to be connected by means of box 13 through a drive nipple 43 to the tubular drive spindle 44 of a rotary power unit 45 of any well known construction. The latter may be electrically operated or may be fluid pressure-operated such as described in my U. S. Pat. No. 3,467,202, issued Sept. 16, 1969. Power unit 45 is carried on a swivel 46 suspended in a well derrick (not shown) on elevators 47 connected to the conventional drawworks (not shown) of a drilling rig, by means of which the power unit and the elements connected thereto may be raised and lowered relative to the well as required in the course of operations. Swivel 46 is provided with a goose neck 48 through which drilling fluid may be circulated through passages communicating with the bores of spindle 44, nipple 43 and bore 12 of mandrel 11 whence the fluid will be directed through casing C to the bit assembly (not shown) to the various discharge passages normally provided therein.

OPERATION

Connector assembly 10 suspended from power unit 45 will be lowered into the upper end of casing C until flange 15 rests on the upper end of the casing (FIG. 2). Right-hand rotational movement will now be imparted by the power unit to mandrel 11 causing expander 20 to move upwardly relative to the mandrel and thereby setting slips 18 into the wall of casing C (FIGS. 1 and 3). Because of the longitudinal arrangement of teeth 33 on shoes 27, pipe-gripping units 26 will slide upwardly on the casing wall for the distance required to accommodate the slip-setting movement of the expander. As slips 18 are tightly set, however, further rotational force applied to mandrel 11 will produce the relative angular movement operative to rock shoes 27 to positions at which such rotational force will be transmitted through teeth 33 as driving torque to the casing. As soon as slips 18 are set, hanger slips G may be removed freeing the casing string for rotation transmitted from power unit 45 to connector assembly 10.

To remove the connector assembly, as when necessary to add another section to the casing string, the string may again be suspended and anchored in hanger slips G, whereupon, reverse or left-hand rotation of spindle 44 by the power unit for only a few turns will be sufficient to back expander 20 away from slips 18, releasing the latter from their gripping engagement with the casing. The connector assembly can now be pulled out of the top of the casing. A new section of casing may now be attached to the upper end of the casing string hanging in the wellhead fitting, and connector assembly 10 inserted in the upper end of the added casing section, and re-actuated by right-hand rotation of the mandrel. Hanger slips G may now be removed and drilling continued.

It will be understood that various alterations 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.

Claims

What I claim and desire to secure by Letters Patent is:

1. A rotary drive connection for well casing, comprising:

a. a connector assemblage bodily insertible into the upper end of the bore of a well casing, said assemblage including:

i. a tubular mandrel adapted to be connected to a rotary drive power source;

ii. pipe-gripping slips mounted about the mandrel for radial movement into and out of gripping engagement with the casing;

iii. expander means mounted on the mandrel for axial movement into and out of wedging engagement with said slips in response to rotation of said mandrel; and

iv. pipe-engaging shoes rotatably mounted about said expander means for angular movement thereby into non-threaded, torque-transmitting engagement with the casing so that upon rotation of said mandrel said expander actuates said pipe-gripping slips into engagement with said casing and upon further rotation said mandrel actuates said pipe-engaging shoes into engagement with said casing.

2. A rotary drive connection according to claim 1 including stop means on the mandrel adapted to engage the upper end of the casing to limit inward movement of said assemblage.