US2699920A - Apparatus for drilling laterally deviating bores from a vertical bore below a casing set therein - Google Patents

Description

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APPARATUS FOR DRILLING LATERALLY DEVIATING BORES FROM A VERTICAL BORR BELOW A OASINOSET THEREIN 2 Sheets-Sheet 2 Filed March 14, 1952 INVENTOR. Ja/m4. Zad/@ United States Patent A APPARATUS FOR DRILLING LATERALLY DEVI- ATING BORES FROM A VERTICAL BORE BE- LOW A CASING SET THEREIN John A. Zublin, Los Angeles, Calif.

Application March 14, 1952, Serial No. 276,521

3 Claims. (Cl. Z55-1.6)

This invention relates to an apparatus for drilling laterally deviating bores from a well bore below the casing set therein.

The drilling of laterally deviating bores from a vertical well bore into the producing formation to increase oil production is now an accepted procedure.

In many oil fields it is the practice to set casing in the vertical well bore at the approximate upper level of a known producing formation. It is often desirable to efrect the drilling of laterally deviating bores into the formation at points below the bottom of the casing after the same has been set. vIt is also desirable to be able to drill multiple, laterally deviating bores in any desired pattern in the formation, that is, to space the laterally deviating bores both circumferentially and vertically with respect to that portion of the well bore below the casing extending down into the producing formation.

It is the purpose and object of the present invention to provide an apparatus in the form of a unit which can be suspended from the lower end of a conventional rotary drill string that is susceptible of being positioned at various vertical elevations near the lower end of the `casing and operative to effect the drilling of laterally deviating bores into the formation below the casing in any desired pattern.

More specifically, the invention contemplates a unit suspendable from the lower end of a conventional rotary drill string which unit 'embraces a tubular head section carrying means for frictionally locking the same to the lower end of the casing, a tubular extension having a whipstock secured to the lower end projectable therewith below the casing, a flexible drill string section rotatable and longitudinally movable within the head section tubular extension thereof and over the face of the whipstock with the drill bit secured to the lower end of said llexible drill string section. l

It is a further and more speciiic object of the invention to provide a laterally deviating bore drilling unit suspendable from the lower end of a rotary drill string and projectable into the formation below the casing which i s provided with means for urging the unit toward that side of the well bore from which the deviating bore is drilled.

Further and more specific objects of the invention will be made apparent as the description proceeds, which will be given in connection with the accompanying drawings forming a part hereof and in which Figure l is a cross-sectional view through the unit showing its position when lowered into a well and ready to be set for drilling a deviating bore, n

Figure 2 is a fragmentary cross-sectional view similar to Figure l showing the unit actually set in the lower end of the casing and disposed in a slightly larger bore than that of Figure l,

Figure 3 is a detailed cross-sectional view illustrating the frictional locking means and the clutch arrangement between the unit and the rotary drill string,

Figure 4 is a detailed cross-sectional view on the line 4-4 of Figure l,

Figure 5 is a detailed cross-sectional View on the line 5--5 of Figure l.

Figure 6 is a detailed cross-sectional view on the line 6-6 of Figure 1, and

Figure 7 is a fragmentary front elevation v iew of the upper end of the flexible drill string section illustrating details of the clutch.

Referring to Figure 1, the well casing 10 is disclosed as set in the casing shoe 11 at the lower end A of the enlarged well bore 12. A smaller diameter bore 13 is illustrated as having been sunk after the casing 10 was set.

Where the bore below the casing is drilled after the casing is set it will, in the absence of underreaming, be of a diameter not greater than the interior diameter of the Casing. In those instances where the casing is set at a given elevation in an already drilled bore, the well bore below the casing may well be of the same diameter as that portion of the well bore in which the casing is set. The latter situation` is illustrated in Figure 2 where the well bore 14 is shown as of substantially uniform diameter both above the point B at which the casing 10 has been set and cemented in and below that point.

The laterally deviating bore drilling unit of the present invention is adapted to be employed for the drilling of deviating bores either from a smaller diameter bore such as illustrated at 13 in Figure l or from a larger diameter bore such as shown at 14 in Figure 2.

Referring now more specifically to the laterally deviating bore drilling unit of the present invention as shown in Figure l, numeral 15 designates the lower end of a conventional rotary drill string which extends to the surface of the Well and is operated by a conventional rotary drillrig. The lower end 15 of the rotary drill string threadedly receives the uppermost unit 16 of the flexible drill string section 17 which, apart from the details of construction of the uppermost unit 16 thereof which will be later described, may take the form of the flexible drill string member disclosed in my prior U. S. Patent 2,515,366, though it will be understood that it may also take the form of the flexible drill string section illustrated in my application Serial No. 255,025, now Patent No. 2,684,581. The flexible drill string section 17 carries the bit 18 at the lower end thereof through the medium of the sub 19 constituting the lowermost unit of the liexible drill string section 1'7. The arrangement is such that the rotary drill string 15, flexible drill string section 17 and bit 18 rotate in unison and are positively driven from the surface of the well. A tubular head section 20 surrounds the lower end of the drill string 15 and, in the position shown in Figure l, the upper end of the flexible drill string section 17. Details of the head section are somewhat better illustrated in Figure 3 which is a fragmentary cross-sectional view at right angles to the showing in Figure l.

It will be observed that the tubular head section 20 is provided at its upper end with the collar 21 in which the rotary drill string 15 is adapted to be rotated and through which it may be downwardly projected. The lower face of the collar 21 is provided with a pair of clutch teeth 22 adapted to interengage with the clutch teeth 23 of the upper unit 16 of the exible drill string section 17, When the rotary drill string 15 is elevated so that the clutch teeth 23 are cammed to engage with the clutch teeth 22, it will be appreciated that the head section 20 and those elements carried thereby to be later described can be rotated with the drill string 15 and the liexible drill string section 17. The head section 20 is provided with a conically shaped, enlarged portion 24 having vertically extending dovetailed keyways 25 for receiving and guiding the complementary keys 26 of the friction shoes 27 which, in the embodiment illustrated, are three in number. When the friction shoes 27 are at their lowermost position in the keyways 25 in the conical enlargement 24 of the head section 20, they will be retracted as shown in Figures 3 and 5.

During the lowering of the unit into the casing 10, the shoes 27 are held in their lowermost or retracted position by the locking dogs 28 pivotally mounted at 29 just above the enlarged conical portion 24 of the head section 20. The locking dogs 28 are so constructed that in the position occupied thereby in Figures 1 and 3 they abut the upper ends of the friction shoes 27 and prevent the same from sliding upwardly in the keyways 25. Thus, in the position of the locking dogs 28 and the friction shoes 27 shown in Figures l and 3, the head section 20 can be freely moved down through the casing 10. The lower end of the head section 20 carries the coupling member 30 into which is threaded the tubular extension 31, which may be of any predetermined length which will approximate the length of the laterally deviating bore to be drilled. While, for purposes of illustration,` I have shown Patented Jan. 18, 1955' the tubular extension 31 and the exible drill string section" 17 as each constituting onel continuous section, it is to be understood that where deviating bores of substantial length are to be drilled, these` elements may be comprised of more than one section. The tubular extension 31 receives at its lower end the collar 32. of the whipstock 33 having the curved bit-deiiecting face 34.

It is av feature of the laterally deviating bore drilling unit that when it is in position to drill a deviating bore it is constantly urged toward that wall of the existing vertical bore at which the deviating bore is to be drilled. To this end the whipstock- 33 is provided with a cylinder 35 in which the piston 36 is adapted to move. An adjustable plug 37 is positioned in the lower end of the cylinder 35 and a coil spring 36 interposed between adyustable plug 37 and the piston 36.

It will be appreciated that the tension on the sprmg 38 can be adjusted by turning the plug 37 which 1s threadedly received in the lower end of the cylinder 35. Pivotally connected to the upper end of the plston 36 at point 39 is a spring link 40 having its upper end pivotally connected at 41 to the whipstock at a point opposite the curved face 34 thereof. The whipstock 1s recessed as indicated at 42 to accommodate the exible link 40. The arrangement is such that when the tubular extension 31 and the whipstock 33 are projected below the casing l() into that portion of the well bore surrounded only by the formation, the flexible link 40, under the influence of the coil spring 33, will be bowed outwardly in a direction directly opposite that of the curved face 34 of the whipstock with the result that when the flexible link 4t) contacts the wall of the well bore the force of the spring 38 will urge the whipstock against the wall of the existing bore from which the deviating bore is to be drilled. lt will be appreciated that there is sufficient normal resiliency in the tubular extension 3]. to permit the whipstock to be moved laterally into contact with the well bore.

When the laterally deviating bore drilling unit has been lowered through the casing l@ with the tubular extension 31 and theV whipstock 33 projected therebelow to a point at which the laterally deviating bore such as indicated at 43 is to be drilled, the locking dogs 28 may be released by dropping an annular weight 44 (see Figure 2) from the surface of the well down over the rotary drill string 15. The weight 44 will pass down over the collar 21 of the tubular head section 20 and contact with the dogs 2S, causing them to pivot about their pivots 29 and release the friction shoes 27 for upward movement in the keyways 25. When this occurs, the coil spring 45,

which has been maintained under tension between the casing 10. The weight of the head section 2), tubular extension 3l. and whipstock 33 all tend to cam the friction shoes 27 into tight engagement with the inner wall of the casing and hoid the unit suspended below the point of engagement of the friction shoes 27 with the l casing 10. @nce the friction shoes 2.7 have been engaged i with the wail of the casing 10, the unit cannot be lowered to a lower level in the well. However, by upward pull on the rotary drill string 15, the upper unit 16 of the ilexible drill string section 17 can be brought into contact with the lower face of the collar Zl of the head section 2t) and the head section 29 raised. This raising of the head section Zi, of course, lifts the conical portion 24 thereof and tends to release the friction shoes 27. A further upward pull on the rotary drill string l5 will permit the entire unit to be raised within the casing 1i) and if it is desired to drill deviating bores at higher levels than that at which the rst deviating bore was drilled 4 the unit can be again set at a higher level in the casing by merely lowering the drill string 15' to permit the spring 45 to again force the friction shoes 27 into engagement with the inner wall of the casing 10. Likewise, when the friction shoes 27 have been released by an upward pull on the rotary drill string 15 which will have also caused the clutch teeth 23 to engage the clutch teeth 22, the unit can be rotated through a partial revolution to orient the same so as to drill deviating bores at circumferentially spaced points around the existing well bore. From the foregoing it will be appreciatedthat I have devised a convenient apparatus for drilling deviating Y bores at points below that at which casing is set in a Wellythrough the employment of conventional rotary drilling technique.

Having thus described my invention what I claim is: l. Apparatus for drilling laterally deviating bores from that portion of a vertical well bore below the casing set therein comprising, a tubular head section, releasable frictional gripping means for holdingthe same near the bottom or the casing, a tubular extension below said head section of smaller external diameter than the internal diameter of the casing, a whipstock attached to the lower end of said tubular extension and projectable therewith beyond the lower end of the set casing, a ilexible drill string section rotatable and longitudinally movable within the said head section and tubular extension, means for connecting the upper end of said flexible drill string section to the lower endv of a rotary drill string and means for preventing vertical withdrawal of said ilexible drill string section from said tubular head section.

2. Apparatus for drilling laterally deviating bores from that portion of a vertical well bore below the casing set therein comprising, a tubular head section, releasable frictional gripping means for holding the same near the bottom of the casing, a tubular extension below said head section of smaller external diameter than the internal diameter of the casing, a whipstock attached to the lower end of said tubular' extension and projectable therewith beyond the lower end of the set casing, a ilexible drill string section rotatable and longitudinally movable within the said head section and tubular extension. means for connecting the upper end of said flexible drill string section to the lower end of a rotary drill string, means for preventing vertical withdrawal of said flexible drill string section from said tubular head section and clutch means between said head section and said iiexible drill string section engageable upon complete retraction of said exible drill string section to permit rotation of said head section, tubular extension and whipstock with respect to the casing.

3. Apparatus for drilling laterally deviating bores from that portion of a vertical well bore below the casing set therein comprising, a tubular head section, releasable frictional gripping means for holding the same near the bottom of the casing, a tubular extension below said head section of smaller external diameter than the internal diameter of the casing, a whipstock attached to the lower end of said tubular extension and projectable therewith beyond the lower end of the set casing, a flexible drill string section rotatable and longitudinally movable within the said head section and tubular extension, means for preventing vertical withdrawal of `said ilexible drill string section from said tubular head section, means for connecting the upper end of said flexible drill string section to the lower end of a rotary drill string and resilient means carried by the whipstock for contacting the wall of the well bore and urging the whipstock in the direction of the working face thereof.

No 4references cited.

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