US2712436A - Flexible well drill collar - Google Patents

Description

July 5, 1955 J. s. M CUNE ET AL 2,712,436

FLEXIBLE WELL DRILL COLLAR 2 Sheets-Sheet l mil 4? Filed March 51, 1952 d HN ($0 MCU/VE,

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United States Patent FLEXIBLE WELL DRILL COLLAR .lohn S. McCune and William E. Hanks, Long Beach, Calif., assignors to Oilwell Drain Hole Drilling Co., 7 Long Beach, Calif., a corporation of California Application March 31, 1952, Serial No. 279,557

9 Claims. (Cl. 25528) This invention has to do with equipment for drilling well bores diverted at such angularities from the initial straight hole, as to necessitate the use of a flexible drill string section or drill collar. Such equipment particularly is adaptable for the drilling of so-called drain holes or bores, which are divertable within a Wide range of angularities so as to be capable of oil-draining the formation from any of selected locations about the main bore. The invention is concerned primarily with the structural features and operative advantages of the flexible drill string section or drill collar.

The present drill collar may be characterized in common with prior flexible drill shafts of this type, as comprising a series of tubular sections having interlocking end lobular projections giving adjacent sections capacity for relative lateral movcemnt, and imparting such general flexibility to the drill collar throughout its length, as will permit great angular deflection of the bit and the course of the drain hole.

One of our major objects is to provide an improved arrangement of lobular interconnections between the drill collar sections that will permit their relative lateral swinging movement in either of right angle planes at the same location longitudinally of the drill collar. Specifically the invention contemplates the formation, as by torch cutting out of a single. stand of pipe, inter-section joints each comprising four lobes spaced at ninety degrees and positioned longitudinally of the pipe in essentially the same transverse plane, the lobes on one section interfitting with companion lobes on the adjacent section so that the sections may swing relatively about either of two pairs of diametrically spaced lobes and corresponding recesses.

A further feature of the invention is the shaping of the lobes so as to give curved surface interengagement of the end surfaces of the sections, while maintaining for the benefit of maximum bearing strength, surfaces of relatively great extent and lesser curvature at the end faces of the lobes and bases of the recesses, as compared with the extent and curvature of the side faces of the lobes and recesses.

Also contemplated is a lobe formation giving the drill Fatented July 5, 1955 Fig. 5 is a developed view illustrating the particular shape characteristics of the interlocking lobes; and

Fig. 6 is a cross-section on line 66 of Fig. 3.

Referring first to Figs. 1 and 2, the drilling equipment is shown to be run down in the Well bore 10 and to comprise a drill string which includes the upper standard drill pipe 1.1 extending up to the ground surface, and the flexible drill collar 12 carrying at its lower end an appropriate drill bit 13. It may be desirable for the drill collar to operate within and out of a tubular sheath generally indicated at 14 which serves the dual functions of a housing for the drill collar, and of a carrier for the whipstock 15. The structural and operative relationships of the drill collar and its sheath are more particularly dealt with in our Patent No. 2,667,332, issuedlanuary 26, 1954.

Referring to Figs. 2a and 2b, the drill collar 12 is con; nected to the pipe string 11 by way of a tubular sub 16, the upper threaded box end of which receives pin 17 of the tool joint 13. The lower pin end 19 of the sub is threaded into the uppermost tubular section 20 of the drill collar. The drill collar 12 may consist of a single length or stand of pipe from which are cut the later described lobular joint sections, or a single drill collar assembly may include a plurality (typically 3 or 4) of pipe stands or lengths 12a. and 12b interconnected as by the right hand threaded joint at 21.

The bottom drill collar section 22 has a pin end threaded at 23 with a knuckle joint generally indicated at 2-; which forms a flexible connection between the drill collar and the bit 13. The knuckle joint is shown to comprise a tubular body 25 containing a concave seat 26 engaged by the spherical head 27 of the knuckle 28. The latter has a stem 29 threaded into shank 30 of the drill bit. The head 27 contains diametrically opposed arcuate grooves 51 which receive the inner ends of pins 32 carried by the body 25, so that the knuckle is capable of universal movement. Upward displacement of the knuckle head from its seat 26 is limited by engagement with the concave face 33 of the retaining insert 34, up ward displacement of which is limited by engagement with the end of drill collar section 22 at 35. As will be understood, upon breaking the joint at 23 and disconnecting the bit from the knuckle 28, the latter may be removed from the body 25 upwardly through its bore 36. Fluid circulation from the tubular drill collar to the bit 13 occurs by way of bore 37 within insert 34, and an alined bore in knuckle 23. By-passing of circulation fluid around the outside of the insert may be prevented by applying to the insert a rubber seal ring 49 which is engaged against the bore wall 36. Below the knuckle collar such unbalanced characteristics under longitudinal 7 load, as will create a tendency for the drill collar to deflect at its lower end and thus facilitate directed deflection of the drill bit. 1

The invention has various additional features and objects all of which will be most readily understood from the following detailed description of an illustrative embodiment shown by the accompanying drawings, in which:

Fig. l is a general view showing the flexible drill collar and outer sheath assembly run in the well;

Figs. 2a and 2b are enlarged sectional and vertically continuing views of the drill collar, bit and sheath assemy;

Fig. 3-is an enlarged view showing in elevation one of the multiple lobe flexible joints in the drillcollar;

Fig. 4 is a cross-section on line 4-4 of Fig. 3;

joint, the bit shank is shown to carry spiral flights 41 enengageable with the formation to properly guide and stabilize the bit.

The invention is more particularly concerned with the structural make-up of the drill collar 12 and the interlocking relation between its relatively movable sections. Between the top and bottom sections 26 and 22, the drill collar includes a series of intermediate sections 42, interconnected at vertically spaced locations 4-3 in a manner such that, at each of those locations, adjacent sections are capable of relative lateral or swinging movement in two different vertical planes which are spaced apart circularly about the drill collar and which pass essentially through the axis of the collar. As best illustrated in Figs. 3 and 5, each joint at 43 is formed by four lobes 44 projecting at 90 spacing from the adjacent ends of the interconnected sections 42 so that the lobes on one section are received within the correspondingly shaped recesses between the lobes on the adjacent section. As particularly shown by the developed view in Fig. 5, each lobe 44 has an end face 45 of relatively greater arcuate locking lobes hole, will retain its oriented position.

extent and lesser degree of curvature, and side faces 46 of relatively lesser arcuate extent and greater curvature. As illustrative, assuming the sections 42 to be cut from pipe having an outside diameter of five inches, and an inside diameter of two inches, the end faces 45 of the lobes may be cut on a radius of two inches through an arcuate extent of about 60 degrees between points a and b; and each side face 46 may be cut on an arc of /8 inch radius through an extent of about llO degrees. So shaped, the lobes are given load-assuming bearing faces 45 of relatively great arcuate extent and area, and therefore greater Wear and abrasion resistance under the com pressive forces axially applied to or assumed by the drill collar during its operations. As illustrated in Fig. 4, the edges of the lobes 44 are tapered inwardly at the joint sections with such clearances existing at 47 between all opposed edges of the lobes, as will assure the relative movability of the interconnected sections 42. In this connection the invention is believed to mark the first instance in which it has been proposed to so provide or arrange interlocking lobular projections on flexible drill collar sections so that adjacent sections are relatively movable in the two 90 spaced planes of each pair of diametrically opposed lobes, at the same transverse plane or location along the drill collar.

Since it is desired to produce in cooperation with the later described whipstock, lateral deflection of the bit and lower end of the drill collar in response to force applied downwardly and axially of the drill collar, it is advantageous that adjacent sections 42 have an unbalanced relation in the sense that the downwardly applied load tends to swing one section relative to the other about one or the other pair of the diametrically opposed lobes 44. Stated otherwise, it is desirable that there be at least slight variance in the bottom support given one diametrically opposed pair of depending lobes 44, as against the other pair, so that the sections will tend to fulcrum initially about the point of end engagement between .the first mentioned pair. This unbalanced relation may be effected in different ways as by forming the end faces 45a of alternate lobes 44:: at slightly greater length than the corresponding faces of the remaining pair of lobes 44 (assuming the recesses receiving all the lobes 44 and 44a to have the same depth), or by hard facing the end surfaces 45a so that because of their greater wear resistance, the lobe so treated will tend to retain their initial dimensions as against greater wear of the alternate untreated lobes, and therefore become fulcrum-points as the interlocking surfaces of the drill collar undergo wear.

Wearing and abrasion of the drill collar as by reason 'ofits engagement with the later described sheath 14, may be minimized by providing each or some of the sections 42 with anti-friction means at locations between the inter- Thus as illustrated in Fig. 2b, a typical form of anti-friction means 48 may consist of a rubbot link 49 seated within a sur ace recess 56 in the sec tion 42, and held thereto as by cementing or the grip of the rubber.

Referring again to Figs. 1 and 2a, the sheath 14 is shown to comprise a tubular body 51 having upper and lower sections 52 and 53 interconnected by left-hand threaded joint at 54. As Fig. 1 shows, the length of the sheath is sufficient to contain the full length of the drill collar anddrill bit as the'asscmbly is being lowered. into the well. At its lower end the'sheath is connected at 55 to a tubular whipstock body 56 having a side opening 57 at the bottom of'which is a solid angular deflecting or whipstocking face 58. The bottom of the whipstock may be suitably supported as by a stand 59 carrying an anchor or shoe 60 which when set and oriented in the bottom of the As illustrated in Fig. 2a, the sub 16 carries a plurality of circularly spaced lugs or ribs 61 which are receivable between lugs 62 formed on the lower end of a tubular insert 63 in the upper end of the sheath. Initially the drill string is releasably held against downward movement relative to the sheath by a shear pin 64 threaded through the sheath and insert 63 into the sub 16. 1

Provision is made for maintaining closed circulation from the drill pipe 11 through the flexible drill collar 12 to the bit 13, by way of arubber hose 65 contained in the drill collar bore and terminally retained within the end sections 20 and 22 of the drill collar in any suitable manner. Merely as illustrative, the upper end hose coupling 65 is shown to be connected by fitting 67 with a tubular adaptor 68 which is seated downwardly against the shoulder 69. The lower end of the hose is shown to have a.

floating connection with the drill collar section 22 within its bore 70, as by way of fitting71 connecting the hose coupling 72 with a tubular insert 73.

In a drain hole drilling operation the drill collar, sheath and whipstock assembly may be set on bottom as shown in Fig. l and appropriately oriented to position the whipstoch face 58 for deflection of the bit in the desired direction. Thereafter, sufiicient load is applied to the drill string to shear pin 64 and thus permit downward movement of the drill collar within thesheath to the point of engagement of the drill bit 13 with the whipstock face 58 and the formation at the side of the well bore opposite the whipstock face. Drilling is then started, with the bit and drill collar being progressively deflected in a direction and at an angle corresponding to the orientation'and angularity of the whipstock face. The deflected bore 10a thus may be drilled to a distance corresponding to the length of the drill string from the bit to the uppermost drill collar section 29. Upon completion of'the drilling, the drill collar and bit may beretracted back into the sheath and the entire assembly pulled from the well, if only a shingle drain hole 10a is to be drilled, or the whipstock may be reset at a different oriented position for drilling of a second drain hole in a different direction. In the latter event, the drill string is raised to the Fig. 2a position of interengagement between lugs 61 and 62, and the whipstock is raised off bottom and oriented in a different direction, following which the previously described drilling procedure may be repeated.

Should it be desired to leave the whipstock in the well tional structure of the sheath 51 permits removal of the' drill string separately from the whipstock. With the drill string elevated to the Fig. 2a position, right-hand rotation of the drill unscrews the joint at 54, freeing the upper sheath section 52 for removal from the well with the drill string.

We claim:

1. A flexible well drill collar comprising a series of tubular sections each having at one end two pairs of projecting curved edge lobes received within corresponding recesses in the end of an adjacent section, the lobes of each being diametrically opposed and the pairs being arranged at 90 degree spacing about the axis of the section, and the-lobes of both pairs terminating in about the same transverse plane of the section so that adjacent sections have relative universal movement at the same location ongitudinally of the drill collar, both ends of each section having continuous alternately convex and concave curvatures defining said lobes and recesses, each lobe having a reduced width neck, and the individual lobes hav- 'ing end bearing edges curved essentially circularly at a v75 in the end of an adjacent section, the lobes of each pair being diametrically opposed and the pairs being arranged at 90 degree spacing about the axis of the section, the lobes of both pairs terminating in about the same transverse plane of the section so that adjacent sections have relative universal movement at the same location longitudinally of the drill collar, and one pair of lobes being slightly longer than the other pair so that the sections connected thereby tend to be unbalanced under longitudinal compression.

3. A flexible Well drill collar comprising a series of tubular sections each having at one end two pairs of projecting curved edge lobes received within corresponding recesses in the end of an adjacent section, the lobes of each pair being diametrically opposed and the pairs being arranged at 90 degree spacing about the axis of the section, the lobes of both pairs terminating in about the same transverse plane of the section so that adjacent sections have relative universal movement at the same location longitudinally of the drill collar, both ends of each section having continuous alternately convex and concave curvatures defining said lobes and recesses, and one pair of lobes being slightly longer than the other pair so that the sections connected thereby tend to be unbalanced under longitudinal compression.

4. A flexible Well drill collar comprising a series of tubular sections each having at one end two pairs of projecting curved edge lobes received within corresponding recesses in the end of an adjacent section, the lobes of each pair being diametrically opposed and the pairs being arranged at 90 degree spacing about the axis of the section, the lobes of both pairs terminating in about the same transverse plane of the section so that adjacent sections have relative universal movement at the same location longitudinally of the drill collar, each lobe having a reduced width neck, the end bearing edge of the lobe having circular curvature at a greater radius and the continuing side edges of the lobe being curved at a smaller radius, and one pair of lobes being slightly longer than the other pair so that the sections connected thereby tend to be unbalanced under longitudinal compression.

5. A flexible well drill collar comprising a series of tubular sections each having at one end a pair of diametrically opposed curved edge lobes received within corresponding recesses in an end of an adjacent section to form a pivotal joint, a successive joint including a similar pair of lobes and recesses arranged angularly about the drill collar axis relative to the first mentioned pair of lobes, each lobe having a reduced width neck, the individual lobes having end bearing edges curved substan- 6 lar pair of lobes and recesses arranged angularly about the drill collar axis relative to the first mentioned pair of lobes, each lobe having a reduced width neck, certain of said lobe pairs being slightly longer than other angularly ofi'set pairs so that the sections tend to be unbalanced under longitudinally applied compression.

7. A flexible well drill collar comprising a series of tubular sections each having at one end a pair of diametrically opposed curved edge lobes received within corresponding recesses in an end of an adjacent section to form a pivotal joint, a successive joint including a similar pair of lobes and recesses arranged angularly about the drill collar axis relative to the first mentioned pair of lobes, each lobe having a reduced width neck, the end bearing edge of the lobe having circular curvature at a greater radius and the continuing side edges of the lobe being curved at a smaller radius, certain of said lobe pairs being slightly longer than other angularly oifset pairs so that the sections tend to be unbalanced under longitudinally applied compression.

8. A flexible well drill collar comprising a series of tubular sections each having at one end two pairs of projecting curved edge lobes received within corresponding recesses in the end of an adjacent section, the lobes of each pair being diametrically opposed and the pairs be:

ing arranged at 90 degree spacing about the axis of the section, and the lobes of both pairs terminating in about the same transverse plane of the section so that adjacent sections have relative universal movement at the same location longitudinally of the drill collar, the end edges of one pair of opposed lobes being curved difierently than the corresponding edges of the other relatively angularly ofiset pair so that the sections tend to be unbalanced under longitudinal compression.

9. A flexible Well drill collar comprising a series of tubular sections each having at one end a pair of diametrically opposed curved edge lobes received within corresponding recesses in an end of an adjacent section to form a pivotal joint, a successive joint including a similar pair of lobes and recesses arranged angularly about the drill collar axis relative to the first mentioned pair of lobes, each lobe having a reduced width neck, and the end bearing edges of certain pairs of opposed lobes being curved difierently from the corresponding edges of other relatively angularly offset pairs so that the sections tend to be unbalanced under longitudinal compression.

References Cited in the file of this patent UNITED STATES PATENTS 1,314,601 McCaskey Sept. 2, 1919 1,739,756 Granville Dec. 17, 1929 1,814,183 Patterson July 14, 1931 1,854,339 Lamb Apr. 19, 1932 2,515,366 Zublin July 18, 1950 FOREIGN PATENTS 81,017 Switzerland May 1, 1919

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