US3015500A

US3015500A - Drill string joint

Info

Publication number: US3015500A
Application number: US785755A
Authority: US
Inventors: Paul B Barnett
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1959-01-08
Filing date: 1959-01-08
Publication date: 1962-01-02
Anticipated expiration: 1979-01-02

Description

Jan. 2, 1962 P. B. BARNETT DRILL STRING JOINT Original Filednec. 5. 1955 FOUL 5. 542N577 IN VEN TOR.

w m an aw United States Patent 3,015,500 DRILL STRlNG JOINT Paul B. Barnett, Glendora, Calif., assignor to Dresser Industries, Inc, Dallas, Tex., a corporation of Delaware Continuation of application Ser. N 550,932, Dec. 5, 1955. This application Jan. 8, 1959, Ser. No. 785,755 4 Claims. (Cl. 285-47) The present invention relates to drill strings such as are employed in drilling oil and gas wells, and more specifically relates to a safety joint for connecting together two lengths or sections of drill tubing. It is common practice in drilling oil or gas Wells to employ a drill string comprising interconnected lengths of drill pipe or tubing, the junctures of which are formed of box and pin ends having interfitting and complementally threaded tapered portions adapted to be turned together to form a rigid, fluid-tight coupling or joint. The hollow interiors of several lengths of tubing form a passageway for the downward flow of drilling fluid to the bit supported at the lower end of the drill string, from which point the drilling fiuid returns to the top of the borehole through the annular space encircling the drill string.

This application is a continuation of the copending application of Paul B. Barnett, Serial No. 550,932, filed December 5, 1955, now abandoned.

Under certain conditions it is desired to produce electrical logs of the earths strata or formations as the drilling proceeds, and for this purpose one or more of the lower drill collar sections of tubing may be insulated from the remainder of the drill string and/ or the drill bit. Insulation is effected by covering the interior and exterior of a portion of one or more of the drill collar sections with an insulating medium such as a rubber coating, and by providing an insulating medium in one or both of the joints contained in the insulated length of the drill string. Due to the extremely adverse environmental conditions under which the lower end of the drill string operates in drilling, considerable difi'iculty has been experienced with such insulated joints, the joints becoming loosened or failing completely, thus resulting in occasional expensive fishing operations. Further it sometimes occurs that a drill bit will become stuck or hung up for a short period of time, during which the drill string winds up as a torsion spring and builds up sufi'lcient torque to free the drill bit, following which the drill bit and lower portion of the drill string are rotated at an'unusually high rate of speed which may cause the drill bit to spin oil the lower end of the drill string. This, too, necessitates a fishing job which involves a complete round trip with the drill string.

The present invention provides means for overcoming the mentioned difiiculties experienced with conventional drill string joints, whether of the insulated or not-insulated type. The invention provides means whereby when a joint becomes loosened or fails, the two tubing sections forming the faulty joint remain mechanically connected by an auxiliary means which permits withdrawal of the lower section of tubing along with the upper section and eliminates the expensive fishing job. The present invention is particularly adaptable to plain tapered joints and to pin-connected joints, but is also suitable for conventional box and pin threaded joints, as will become evident from a consideration of the following specification. To illustrate the principles of the invention, it is herein illustrated and disclosed in connection with a conventional threaded box and pin joint and a plain tapered insulated joint. It will be understood, however, that the invention is applicable to other suitable types of drill string element joints.

Referring now to the drawings forming a part of this specification,

FIGURE 1 is a view in elevation of a drill string tubing joint of modified box and pin type, with means according to the present invention applied thereto, and with portions broken away and parts shown in section;

FIGURE 2 is a view in elevation of a plain taper drill string tubing joint of the insulated type, with means according to the present invention applied thereto, portions having been removed for purposes of illustration, and with some parts being shown in section; and

FIGURE 2A is a view of a portion of FIGURE 2 enlarged, better to illustrate the arrangement of various parts thereof.

Referring now to FIGURE 1, there are shown upper and lower elements or sections 12 and i4, respectively, of conventional drill string joined in a conventional box and pin type joint. The upper section 12 has a lower threaded tapered portion 16 which has been stabbed into and turned into tight joining relation with the upper internally threaded portion 18 of section 14. While the joint thus far described may be as illustrated, that existing between adjacent interconnected sections of drill string tubing, it will be understood that the joint may as well be that existing between a section of tubing and a drill collar, or that existing between a section of drill tubing or drill collar and a drill bit, or other drill string elements, such joints being of similar form and construction, as is well understood in the art. Due to the extreme degree of shock and vibration incident to contact and relative motion of the drill bit and drill string with respect to the earth formation, and/ or the high torsional stresses to which drill string is subjected, any of the joints may become loosened or otherwise fail in service. When the two elements of drill string forming the joint thus separate or fail in service, further drilling with the rig cannot be accomplished until the defective elements have been replaced. The upper portion of the disjointed drill string is removed, and the lower portion is then fished out by special apparatus, as is well understood in the art.

The means provided by the present invention eliminates all phases and aspects of the mentioned type of fishing operation, and reduces replacement of the detective joint to a mere pulling of the drill string sufiicient to expose the defective joint at the top of the borehole, replacement of the defective elements, and return of the string into place. In accordance with the present invention, and as depicted in FIGURE 1, the upper section 12 of drill string is provided with one or more recesses and preferably a single peripheral recess 2%) extending around its exterior adjacent to but spaced from the threaded portion 16; the recess being preferably of the cross-sectional shape and form there shown. The lower section 14- of drill string is provided with one or more similar recess means, and preferably with a single annular recess 22 adjacent to but suitably spaced from the threaded portion 13. A split sleeve structure, indicated generally by ordinal 24, and which may comprise one, two or more longitudinally extending sections, is formed and arranged with shaped internal projections such as are indicated at 26 and 28, adapted to fit in and engage in

respective recesses

26 and 22 in a manner and fashion shown in the left portion of FIGURE 1, when the sleeve structure is in assembled form closely encircling the joined portions in and 18 of the respective drill string elements. Preferably the split sleeve structure 24 is formed of material of relatively high tensile strength and is such as to closely engage the exterior surfaces of the appropriate portions of

sections

12 and 14 when assembled. The split sleeve structure when applied to the joined ends of

sections

12 and 14 and with its

projections

26 and 28 engaged in the respective recesses 29 and 22, is adapted to be maintained in assembled relation by suitable means, preferably in the form of high tensile retaining rings or

bands

36 and 32 encircling, respectively, the upper and lower ends of the sleeve structure. The retaining bands may be and preferably are secured in retaining position by suitable means such as, for example, countersunk screws 34 fitted through suitable apertures in the respective rings and engaging in complementary tapped aperatures formed in reduced diameter end portions of the sleeve element or elements as indicated in FlGURE l. The recesses formed in sections 12 and lid for reception of the

projections

26 and 28 of t e sleeve structure are preferably formed with undercut faces at these ends adjacent the respective tubing ends, as indicated in the section View in the left hand part of FIGURE 1, and the projections such as 26 and 23 are formed with complementary undercut portions. Also, preferably but not necessarily, the sleeve structure is urged or biased into contacting relation with one or the other of the notched or undercut sections or portions of the respective recesses by suitable means such as by a ring or'band of flexible material 36 encircling one of the tubing sections and held in place by an overlapping portion of a respective one of the retaining bands 3% or 32 (in the illustrated embodiment by retaining band 32). It will be evident that the sleeve structure, formed and assembled in place as described and indicated, serves as a means to mechanically interconnect the

drill string elements

12 and 14 in the e ent of loosening or failure of their threaded interconnecttion. If the threads of either the box or pin or both fail, the weight normally supported by upper section 12 is transferred from the joint to the sleeve structure 24 by slight upward relative movement of section l2 with respect to section 14 and concurrent interengagement or" the projection or projections as of the sleeve structure with the complementally formed lower faces of the recess 29 formed in upper section 12. lt will'be understood that the material and dimensions of-the sleeve part or parts are made such that the sleeve structure is enabled to thus bear the burden transferred to it. As hereinbefore noted, the sleeve structure may comprise one, two, or more, principal. longitudinally extending elements, but preferably comprises two such elements, of such dimensions as to closely encircle and bear against the junctureforming portions of the two drill string elements. The split sleeve structure 24 may be maintained in the assembled form against outward expansion or displacement by both the bands 3i) and 32 and by one or more of the coacting complementally formed surfaces of the projections 2-6 and 23 and

respective recesses

20 and 22.

Referring now to FIGURE 2, there is depicted an application of the present invention to a form of drill string tubing joint of the insulated type wherein the upper and lower sections of drill string tubing are electrically insulated one from the other. While the type of insulated tubing joint depicted is of the plain tapered species, it will be understood that the present invention may equally well be applied to a wide variety of insulated drill string element joints. In FlGURE 2 an upper drill string tubing section 52 is joined to a lower drill string tubing section 54 by a plain tapered insulated joint comprising a lower tapered portion 56 of upper section 52 and a comple mentally tapered upper portion 53 of tubing section 54, the two portions 55 and 53 being electrically isolated, one from the other, by a coating or layer of electrical insulation 6 1?. The electrical insulation 69 may be in the form of a coating applied to either or both of the portions 56 and 53, or may comprise a separate shell-like member of suitable material installed in the shell of portion 58 prior to the stabbing in of portion 55 and pressed into firm contact with both

portions

56 and 58 as those portions are assembled with the application of great longitudinal com pressive force on the tubing sections. Preferably, but not necessarily, the insulated joint comprises an internal jacket or covering of insulation oz extending over a more or less extensive portion of the bore of the drill string adjacent the joint. According to the present invention, the upper and lower

drill string sections

52 and 54 are provided with recesses, preferably peripheral in form, and

indicated generally at 64 and 66, respectively, similar in form and characteristics to the previously described recesses 2b and 22 shown in FIGURE 1. A split sleeve structure is provided, indicated generally by ordinal and comprising one or more principal longitudinally extending elements and such element or elements having upper and lower internal projections such as ill and 72, respectively, adapted to repose in the respective recesses 64 and es, as indicated. The lower internal projection or projections 72, are, as indicated, arranged to closely lit in respective complementary recess or recesses 66; whereas recess means o l and one or more complementary projection or projections 7d are so relatively formed as to provide clearance "and complete lack of contact between the projection or projections and any part of upper tubing section 52. To this end an appropriate portion of the length of upper tubing section 52 is relieved, as for example, at 7 3 and 75, whereby the sleeve structure, when assembled and mounted in encircling relation around the jointed ends of

sections

52 and 54, is completely out of electrical contact with section 52. This insulated status of the sleeve structure and section 52. is maintained in normal operation of the drill string by a layer of electrical insulation 78 applied over the appropriate outer surface area of tubing section 52. The longitudinally extending element or elements of sleeve structure 6%? are maintained in assembled relationship by a plurality of encircling, prefrably endless, bands and 82 appropriately secured in any suitable manner to the sleeve element or elements, as, for example, by countersunk screws 34 as indicated. The sleeve in assembled relationship encircling the jointed lower end of tubing section 52 and upper end of tubing section 54 is preferably maintained with its lower projections 72 in close contacting relationship with a complementally form d upper portion of the wall of recess means 65 by a means interposed in the lower portion of recess 66; such means being in the form, for example, of one or more G-rings, or a wrapping of steel wire 8 which means may be held in place by lowerband 32 as indicated. From a consideration or" the structure depicted in FlG- URE 2 and so far described, it will be evident that while the sleeve structure as may be in intimate electrical contact with tubing section 54, it is nevertheless electrically isolated from the tubing section 52 by an interposed layer of electrical insulation, thus leaving

sections

52 and 54 electrically isolated, each from the other. As may be usual, a portion of the outermost surface of the lower end of tubing section 52 and ofthe upper end of tubing section 5'4 may be electrically insulated, each from the other and from electrically conductive borehole fluids by means of a coating or jacket of electrical insulation d6 applied therearound subsequent to the assembly of the split sleeve structure around the joint. Thus it is evident that if the joint formed by the box portion 53 of tubing section 5 and the pin portion 56 of tubing section 52 fails, the load normally supported through the joint will be transferred to the sleeve structure 63, and although the insulation may fail, the upperand lower tubing sections will remain mechanically interconnected, whereby the lower section and any parts supported thereby may be removed from the borehole without a fishing operation.

From the preceding description and explanation it will be seen that the invention provides a safety joint for drill string tubing which permits two previously joined drill string elements to remain. mechanically interconnected after failure of their joint, whereby the lower drill string element may be removed from the well or borehole without the trouble, expense and lesser time involved in a fishin operation. While the particular means and joints used to illustrate a preferred embodiment of the invention are of two specific types, it will be evident to those skilled in the art that the principles of the invention are applicable to a wide variety of constructions and types of drill string joints. Accordingly, it is not desired to be limited to the precise details of the illustrated physical embodiments of the invention, but what is claimed is:

1. A drill string joint including in combination: a pair of oppositely-positioned body members including complementarily formed box and pin members thereof interconnected in telescoping, end-to-end coaxial and normally rigid engagement; an external, annular groove formed coaxially around the exterior of each of said body members adjacent said box and pin members such grooves each being formed with the faces nearest the said box and pin members undercut; a longitudinally extending split sleeve member encircling said box and pin members and said body portion; longitudinally spaced-apart, inwardly projecting lug members, of a longitudinal width less than the longitudinal width of the said grooves and having undercut end portions adapted to fit the aforesaid underout faces of said grooves, attached to said sleeve member and extending into the grooves; a flexible ring fitting into one of the grooves between a side thereof and one of said lugs and in close engagement therewith, said ring biasing said sleeve member longitudinally so that said lugs are urged against sides of the groove into which they fit thereby being effective to retain said body members against substantial longitudinal movement with respect to one another in event of failure of the normally rigid joint between said box and pin members; retaining bands extending around said sleeve member and fitting over at least a portion of each of said lugs; and means holding said bands on said sleeve in close engagement with said lugs.

2. A drill string joint including in combination: a pair of oppositely-positioned body members including complementarily formed, threaded box and pin members thereof threaded together in telescoping, end-to-end coaxial and normally rigid engagement; means forming an external annular groove formed coaxially around the exterior of each of said body members adjacent said box and pin members such grooves each being formed with the faces nearest the said box and pin members under cut; a longitudinally extending split sleeve member encircling said box and pin members and said body portion; longitudinally spaced-apart inwardly projecting lug members, of a longitudinal width less than the longitudinal width of the said grooves and having undercut end portions adapted to fit the aforesaid undercut faces of said grooves, attached to said sleeve member and extending into the grooves; a flexible ring fitting into one of the grooves between a side thereof and one of said lugs and in close engagement therewith, said ring biasing said sleeve member longitudinally so that said lugs are urged against sides of the groove into which they fit thereby being effective to retain said body member against substantial longitudinal movement with respect to one another in event of failure of the normally rigid threaded joint be tween said box and pin members while permitting relative rotation therebetween; retaining bands extending around said sleeve member and fitting over at least a portion of each of said lugs; and means holding said bands on said sleeve in close engagement with said lugs.

3. A drill string joint including in combination: a pair of oppositely-positioned body members including complementarily formed box and pin members thereof interconnected in telescoping, end-to-end coaxial and normally rigid engagement; an external, annular groove formed coaxially around the exterior of each of said body members adjacent said box and pin members; a layer of insulating material positioned between said box and pin members and within at least one of the grooves and effective to electrically isolate said body members from one another; a longitudinally extending split sleeve member encircling said box and pin members and adjacent portions of each of said body members; longitudinally spacedapart, inwardly projecting lug members, of a longitudinal width less than the longitudinal width of the said grooves, attached to said sleeve member and extending into the said grooves; a flexible ring fitting into one of the grooves between a side thereof and one of said lugs and in close engagement therewith, said ring biasing said sleeve member longitudinally so that said lugs are urged toward sides of the grooves into which they fit thereby being effective to retain said body members against substantial longitudinal movement with respect to one another in event of failure of the normally rigid joint between said box and pin members while permitting relative rotation therebetween; retaining bands extending around said sleeve member and fitting over at least a portion of each of said lugs; and means holding said bands on said sleeve in close engagement with said lugs.

4. A drill string joint including in combination: a pair of oppositely-positioned body members including complementarily formed box and pin members thereof interconnected in telescoping, end-to-end coaxial and normally rigid engagement; an external, annular groove formed coaxially around the exterior of each of said body members adjacent said box and pin members; a layer of insulating material positioned between said box and pin members and within at least one of the grooves, an internal jacket of insulating material on the internal bores of said body members and coextensive with the joint therebetween, sm'd layer and jacket being eifective to electrically insulate said body members from one another; a longitudinally extending split sleeve member encircling said box and pin members and adjacent portions of each of said body portions; longitudinally spaced apart, inwardly projecting lug members, of a longitudinal width less than the longitudinal width of the said grooves, attached to said sleeve member and extending into the grooves; a flexible ring fitting into one of the grooves between a side thereof and one of said lugs and in close engagement therewith, said ring biasing said sleeve member longitudinally so that said lugs are urged toward sides of the groove into which they fit thereby being eifective to retain said body members against substantial longitudinal movement with respect to one another in'event of failure of the normally rigid joint between said box and pin members while permitting relative rotation therebetween; retaining bands extending around said sleeve member and fitting over at leut a portion of each of said lugs;

and means holding said bands on said sleeve in close.

engagement with said lugs.

References Cited in the file of this patent UNITED STATES PATENTS Re. 21,606 Nielsen Oct. 22, 1940 391,313 Gordon Oct. 16, 1888 1,043,806 Dahl Nov. 12, 1912 1,738,021 Shipley Dec. 3, 1929 1,790,266 Fullmer Jan. 27, 1931 2,267,168 Posey Dec. 23, 1941 2,795,398 Ragland June 11, 1957 FOREIGN PATENTS 738,569 France Dec. 27, 1932 745,184 France May 6, 1933 508,498 Great Britain June 30, 1939