US1895001A - Core drill - Google Patents

Description

Jan. 24, 1933. A E-AD 1,895,001

CORE DRILL Filed Sept. 19, 1930 2 Sheets-Sheet 1' INVENTOR.

Jan. 24; 1933. a. A. MACREADY CORE DRILL Filed Sept. 19, 1930 2 Sheets-Sheet 2 I N VEN TOR. 2247 2. Cl.

Patented Jan. 24, 1933 PATENT OFFICE GEORGE A, MACREADY, OF LOS ANGELES, CALIFORNIA GORE DRILL Application filed. September 19, 1930. Serial No. 482,925.

My invention relates to core drilling in wells and particularly to securing cores which can be oriented to determine the direction of dip of strata or faults.

Orientation of the core is done by orientation of a core receiving tube either by instruments on the core receiving tube or by surveying the twist of the drill string as it is removed from the well, both of which methods can be accomplished by the apparatus disclosed in my application for patent,

Serial Number 107,980 filed May 10, 1926 for Core drill and means for ascertaining dip; and also in my two later applications Serial Number 271.932 filed April 21, 1928 for Core drill with clock operated means for ascertaining dip and Serial Number 430,908 filed February 24:, 1930 for Orientation core drill.

In the instant application for patent an improved core drill is disclosed which is particularly adapted to shallow core drilling where the depth is so small that the drill pipe can be accurately surveyed from the 25 well and for wells in which the amount and direction of deviationof the well hole from vertical is already known or very small.

An object of my invention is a core drill in which the inner barrel is swiveled inside the outer barrel so that the core will not twist apart during coring and in which the swivel is locked against rotation automatically when the drill is lifted off bottom and suspended so that the position of the core relative to the drill stem will not shift during the process of surveying the drill stem from the well.

A further object is an identification index mark on the lower end of the inner barrel which is visible externally so that the inner barrel can be tied to the datum direction as soon as it emerges from the well.

Another object of my invention is an inner core receiving tube or barrel which can be surveyed accurately from the well and in which the core is readily accessible-without excessive handling and disconnections liable to confuse the orientation.

r Another object is a projectionon the extreme lower end of the inner barrel to resist rotation of the barrel about the core, to mark the core and to identify a side of the core.

Another object is a novel form of thrust bearing for the swivel which is economically constructed, very free of movement, requires no packing glands, and has ample circulation channels.

Another object is a simplified mud guard to prevent mud or clay chunks choking the inner barrel to the exclusion of a perfect core.

Another object is a dbris screen over the lower end of the core drill to exclude coarse gritty dbris from the annular space between barrels and from the inner barrel during lowering into a well. This form is adaptable 55 to caving holes in which the cavings are gritty instead of sticky. In some wells coarse grit en ering the drill string from below tends to lodge between the swiveled barrels to lock them together: the screen prevents this di'fficulty.

Another object is .a core drill having a swiveled inner barrel in which the residual torque of the drill pipe resulting from coring is released before breaking the core from the country rock. Goring is done with the drill pipe in compression and torsion. When coring is completed and the first survey observations for orientation are recorded the drill pipe rotation is simply stopped without relieving the strain at the lower end so that the cutting edges arestill exerted against the unfinished bottom chip until the drill pipe is raised. When the drill pipe is raised the strain is relieved by a twist of the drill pipe of unknown amount but of sufficient magnitude to cause an inaccuracy of the orientation of a core if the orientation is attempted with most forms of swivel barrel or other kind of core drills. In the specification it will be seen that I eliminate this source of error. Of course where the recording is done by instruments carried by the inner barrel the twist does not affect the accuracy but some operators prefer to orient cores by surveying the drill pipe and the instant application discloses a core drill particularly adaptedto accurate results for their use.

Another object of my invention is a core drill having an outer barrel rotatable about n the inner barrel during coring, the inner barrel projecting beyond the tubular portion of the outer barrel so that chips shaved off the core by itare easily disposed of and so that the inner barrel is visible for orientation purposes. I

Another object is a bladed cutter head having holes in the blades for attachment of a net to exclude debris from the core drill.

With the foregoing and other objects in view which will be made manifest in the following detailed description and especially pointed out in the appended claims, reference is had to the accompanying drawings for illnstrative embodiment of my invention, wherein:

Figure 1 is a longitudinal section of my core drill,

Figure 2 is a cross section at 2-2 on Figure 1,

Figure 3 is a cross section at 3-:3 on Figure 1,

Figure 4 is across section at 4l-4.on Figure 1,

Figure 5 is a cross section at 5-5 on Figure 1,

Figure 6 is a cross section at 66 on Figure 1,

Figure 7 is a cross section at 7 -7 on Figure 1,

Figure 8 is a. cross section at 8-8 on Figure 1, V

Figure 9 is a grapple for handling the inner barrel,

Figure 10 is an elevation of the lower end of my core drill without the mud guard or screen,

Figure 11 is an elevation of the upper connection of the inner barrel showing the outer barrel in section and with the thrust spider removed,

Figure 12 is a longitudinal section of the lower end of the form of core drill sh own in my co-pending application Serial Number 107.980 previously mentioned.

Figure 13 is a side elevation of the lower end of my core drill with the net for excluding dbris attached thereto.

Figure 14 is an elevation of the bottom end of the assembly shown in Figure 13, and

Figure 15 is a flat view of the net screen for excluding dbris as it appears spread out Similar numerals refer to similar parts throughout the several views.

In the accompanying drawings the principal members of my rotary core drill are the inner core receiving barrel 1 swiveled within the outer barrel 2.

An inner shoe or nose 3 is attached to the lower end of the inner barrel. This shoe is of cylindrical external cross section except for a longitudinal identification mark or scratch 4. The inner cross section shown is nearly circular except for the longitudinal rib 5 although several other forms of internal cross section have been used. The lower end of the nose is beveled outwardly and upwardly from an annuar cutting edge 6. The bore may be tapered or choked at the lower end to lessen friction of the incoming core. A core gripper maybe attached to or adjacent the nose to suit the character of formation. In the form shown, springs or barbs 7 riveted to the upper lip 8 project inwardly and resist escape of the core but are flexible enough to be pushed aside by the incoming core. For many formations a simple shoulder is an efficient catcher.

A combination thrust and check valve body member 9 is attached to the upper end of the inner barrel 1 as by screw threads 10. Washers or shims 11 of chosen length may be used for adjusting the length of the inner assembly. The member 9 is preferably a casting although it may be machined. The lower end is provided with a cross passage 12 and a longitudinal passage 13 forming a cage for the valve ball or closure 14. The

ball may seat on a seat 15 retained by a tubular screw threaded follower 16. The follower 16 may have side holes 17 to allow escape of fluid in the event of the mud guard l5 choking the end passage. The upper portion of member 9 is of reduced diameter to allow circulation between it and the internal upset'of the outer barrel. The extreme end of member 9 is rounded to form a round head 18 functioning as a thrust bearing. A notch 19 is provided for engagement with a grapple for lifting the inner assembly out of the outer barrel or a hole 38 may be provided to receive a hook for the same purpose. Transversely projecting fins 20 are on the external surface of member 9 just below head 18. The fins 20 extend to a greater external diameter than the external diameter of inner barrel 1 and are provided with a downwardly facing surface 21 which is provided with radial notches 22 for a purpose hereinafter described.

A sub or coupling 23 is attached to the lower end of outer barrel 2 to substitute more substantial threads for the soft conventional pipe threads. To provide large circulation space the upset of the pipe 2 is removed, this not being necessary near the base of the drill column. A cutter head 24 is attached to sub 23. The cutter head shown is provided with tour cutter blades 25 each cutting the same gauge externally and internally and projecting a short distance ahead of the hollow portion of the head 24. The internal gauge shouldbe slightly greater than the external diameter of the inner barrel so that the inner barrel can project through. The outer-gauge can be any desired andblades of different gauge and length can be used. The head is threaded internally to fit sub 23 and the middle portion is provided with internal ribs 26 to center the head about the inner barrel during rotation.

At the upper end of the outer barrel 2 the internal upset 27 is retained for strength and a tool joint box coupling 28 attached by screw threads or Welding. The barrel 2 can be a length. of A. P. 1.. (American Petroleum Institute) standard rotary drill pipe and in some sizes the coupling 28 can be-the regular A. P. I. standard size although usually a few slight difl'erences in dimen-.

sions are desirable. The bore of box coupling 28 should be appreciably greater than the internal diameter of the upset 27. The upper end of coupling 28 is threaded internally to receive a tool joint pin 29 and in some sizes this pin can be the regular A. P. 1. standard which results in a saving of special connections and resultant economy and simplification of equipment.

The thrust spider 30 is preferably a bronze castin and consists of a central core or body 31 flan {ed by ribs or fins 32 which extend longitudinally beyond the core to form a socket in each end. The ends of core 31 can be concave as at 33 to form a socket to co-operate with thrust head 18 and the radius of curvature may be slightly larger than that or head 18 so that the bearing is at the 'center spot. Both ends of the spider can be interchangeable. Spidersot different length can be selected from instead of using the shim 11 to adjust the lengths of inner and outer barrels. Small holes 34 drilled through the fins 32 can be provided to receive a hook for lifting the spider out of the coupling 28.

The conventional upset of drill pipe usually tapers both ways from the maximum thickness of metal. A thimble or bushing 35 inserted inside the tapered end and held against rotation by a set screw 36 provides a cylindrical inner wall and a full width shoulder at the upper end of the drill pipe piece. The upper end of this bushing may be provided with notches 37 of a size suitable to co-operate with ,the notches 22 of member 9. The

' integral with coupling 28, or a bushing inside coupling 28. When the core drill is suspended from the drill pipe stringathe inner barrel organization is supported by the fins 20 hanging 'on'bushing 35 and when thus suspended the notches 37 mesh in notches 22 and lock both barrels against rotation relative to each other. p y i- Figure 12 illustrates a form of identification mark shown in my co-pending application Serial Number 107 .980 and consists of a screw 47 projecting through the wall of inner barrel 48 so that point of the screw isvisible on the inside and the slotted head &9 visible from the outside. The cutter head of the outer barrel which revolves about the inner barrel includes blades 50 projecting below a cylindrical hollow portion 51. The screw 47 and edge 52 of the lnner barrel a re visible between the blades below the central hollow portion of the cutter head.

A grapple is shown in Figure 9 for use in assembling and removing the inner barrel consisting of a body portion 39 having an eye 40 and spring prongs 41 urging outwardly with hooks 42 at their ends. The sleeve 43 draws the prongs together over the head 18 and is held by a removable pin 44. Instead of this grapple a chain or cable loop around recess 19, a hook inserted into holes 38 or other means can be used.

During lowering into a well, mud including chunks of cavings scraped from the wall of the well is pushed ahead of the core drill and is drawn into the drill by rush of liquid filling the drill pipe from below. Large chunks cause trouble by plugging the core barrel to exclude core. To avoid this difficulty a mud guard of very simple form is provided consisting of a single stick of wood 45 to which downwardly pointing'spring barbs 46 are tacked. The wood piece is ta-. pered so that the small end having the barbs can be inserted into the bore of the barrel leaving the large end projecting. The barbs book over the core grlpper to support'the guard and the large end is of greater diameter than the bore of the barrel so that it cannot enter until cut oil by the sharp edge of the inner barrel nose 3. As shown in Figure 8 the wood is preferably of rectangular section so that a passage is left around it to admit liquid without chunks to fill the drill pipe. v Other forms ofmud guards have been disclosed in my applications Serial Number 346,955 filed March 14. 1929, and Serial Number 430,908. filed February 24, 1930. Heavy wood, either natural or weighted is preferred so that the guard will ride lightly (in the top of the core but not fioat abovethe core.

The mud guard above described, is best suited where the cavings in the well are of clayey character. Chunks of clay can efiectually block the barrel against incoming core by lodging in the'check valve but'the clay plug. However, when the hard pebblesget into the space between the bagrels they are not crushable and only a few of the larger.

locking action is undesirable in the swivel type of core drill and may spoil the core for urposes of orientation. The above remar s emphasize the different effects between clay and gritty cavings on a core drill.

For gritty cavings a screen made of fishnet material fastened over the entire cutter head is useful and effective. Figure 15 illustrates a net opened out flat consisting of a fabric net 58 with say quarter inch spaces between strands and cut in a clover leaf shape. Edges can be reinforced asat 59 and strings or wires 60 provided for tying to the head as illustrated in Figures 13 and 14. When this form is used the edge of the inner barrel pinches it in two cutting out the cen tral portion as fan as slots 61 which allows the outer portions to float away from the circulation outlets. Instead of tying around the cutter head at the top of the blades as illustrated the net can be wired to holes 62 drilled through each blade below the cylindrical portion of the cutter head where there is less danger of the net being scraped off by the well wall during descent.

My core drill is assembled as follows: The outer organization of cutter head 24, sub 23, outer barrel 2 and tool joint coupling 28 is supported in the rotary table on slips.

The inner organization of core receiving tube 1, inner shoe 3, and thrust-check member 9 is picked up by a chain, grapple or hook in recess 19 or hole 38 and lowered into the outer organization. The thrust spider 30 is set on top of head 18, the drill pipe connected by tool joint 29, and the core drill raised for inspection of the lower end. The mud guard or fish net is then attached and th drill lowered into the well. The operation of my core drill is as follows: During lowering into the well the interior organization is supported with the notches 22 meshing in notches 37 so that inner and outer barrels are locked against rotation relative to each other. -When the core drill approaches the bottom of the well the lower end of niud guard 45 (or 58) touches bottom first and stops. The sharp edge 6 ofthe inner'barrel imposed on the wood with weight shaves oil the corners of the stick so that part of thestick can enter the barrel and the shaved off corners escape to the circulation. The stick is now free to lead the core into the inner barrel.

The nose 3 of the inner barrel next touches bottom and the outer barrel follows rotating to dig core. It will be observed that the core dug by the rotary cutters is of larger diameter than the diameter of the inner barrel. The result is that the nose of the inner barrel rests on the top of the core and notches 22 lag behind notches 37 unlocking the barrels to permit the outer barrel to rotate about the inner barrel. The outer cutter head rotates to dig additional core and as it descends the Weight from the drill pipe is applied through spider to head 18 to force, the inner barrel longitudinally over the core. Ordinarily'the lengths are adjusted so that the edge 6 of nose 3 during coring is a fraction of an inch above the edges of cutter head 24, except in very soft formations where the weight of the inner member sinks theedge 6 by gravity ahead of the cutter head 24. With this adjustment the shavings cut by nose edge 6 from the core have a free lateral face to break or shear from and escape directly into the circulation below the tubular part of the outer barrel so that they cannot accumulate between the barrels to lock' them together. Furthermore the unshaved portion of the core protects the inner portion finally recovered from erosion by circulation fluid. The spider 30 rotates on round head 18 as a bearing and this form of bearing has proven very free and practical for operation in muddy slush.

Circulation fluid or slush is pumped down through the drill pipe entering the core drill from passage 53 and passes through central passage 54 of the spider, passages 55 between the fins of the spider, down the annular passage 56 between outer and inner barrels,

but close enough to the shavings to carry them away in the current and that the cutting edges are readily and efliciently cooled; Liqu'id in the inner barrel displaced by the incoming core is vented to the space between barrels, 56.

It'will be readily seen that this core drill hasmany advantages.

When coring-is completed and it is desired .to orient the core by surveying the drill pipe the rotary table is stopped. The cutters then rest on bottom 'with residual torque of the drill pipe pushing slightly against the unfinished bottom chip and held against it by torsional friction of the drill pipe against the well wall. Observation is-taken of the tpp of the drill pipe. The core drillis then pulled up by pulling the drill pipe. The first move lifts the outer cutter head-clear of'the .nnfinished chip'and relieves the bottoinresistance to torque and the torsional friction on the well wall. with the result that the drill pipe resumes its normal untwisted state by a slight twist at the lower end, the upper end being held by the elevators. In a long string but may be considerable and even as much as v a complete revolution. In my core drill,

with usual adjustments the outer barrel must be raised an inch or more before it picks up the inner barrel and it raised slowly the torque twist is relieved before the inner barrel and core are picked up. My construction eliminating the torque twist removes one of the greatest inaccuracies of orienting cores by surveying the drill pipe.

Fins 20 are engaged by thimble 35 or equivalent to support the weight of the inner barrel during raising to the surface. Ngtches 22 and 37 engage so that during raising the inner and outer barrels are locked against relative rotation. In contrast to my construction in most other forms of swivel barrel core drills the barrels are free to swivel while suspended so that vibration during raising can cause their relative positions to shift and spoil the accuracy of the orientation record. With modern rotary equipment usi'nghigh speed cables and reels great vibration is transmitted to the drill pipe when raising. With ;my form the weight of the loaded inner barrel holds notches 22 and 37 positively engaged to prevent rotational shift during raising and thus eliminates another common inaccuracy in orienting cores. When the lower end of the core drill emerges from the well the lower end of the inner shoe 3 is visible between the blades of the cutter head and the position of the identification mark 4 can be observed for orientation. In case the mark is not in a convenient position an additional and diiierently distinct identification mark can be placed on the shoe for record, as by a punch mark. 1

The inner barrel is then remov d from the outer barrel and the core extracted- By of the drill pipe torque before liftin the core' ofi' bottom: An identification mar on the inner barrel visible below the outer barrel: Free circulation passages: a large core cut by the rotary cutters which is not so liable to injury from circulation erosion: Provision for immediately removing shavings cut from the core by the inner barrel before they can get between the barrels: And a niud guard to eliminate clogging of the drill by .cavings.

I claim as my invention: 1. A core drill for orienting cores compris ing an outer barrel a rotary core cutting shoe on the lower end 0 said barrel, an inner core receiving tube within said outer barrel, said barrels being rotatable relative to each other when supported from the bottom and locked against relative rotation when suspended from drill pipe.

2. A core drill for orienting cores comprising an outer barrel, a rotary core cutter 3.. A core drill for orienting cores compris ing an outer barrel, a rotary core cutter on the lower-end of said outer barrel, an inner barrel within said outer barrel having a limitedlongitudinal movement relative to said outer barrel, anda projection on said inner barrel adapted to engage said outer barrel to suspend said inner barrel thereby, said outer barrel beinglocked against rotation about said inner-"barrel when said inner barrel is suspended therein and free to rotate thereabout when the weight of said inner barrel is not supported by said outer barrel.

,4. A core drill comprising an outer barrel having cutters on the lower end thereof and an inner barrelhaving an annular cutting edge on the lower end thereof, a rounded head on the upper end of the inner barrel, a spider having a central body flanked by lateral fins slidable within the upper end ofsaid outer barrel to engage said-head, and a top connection for the outer barrel to lock said spider between said head and said connection to form a thrust bearing, said fins extending beyond the central portion to form a socket "at one end within which said head can revolve against the end of said central body portion.

5. A core drill comprising an outer barrel havin cutters on the'lower end thereof, an inner arrel having an annular cutting edge on the lower end thereof, a blunt head on the upper end of the inner barrel, a top connection on said outer barrel, and a spider slidably disposed within' the outer barrel between said head and said connection to form a thrust bearing, said spider having a central body portion flanked by lateral fins extending beyond the ends of said body portion to form a socket within which said blunt head can revolve against the end of said central body-portion.

'6. A core drill comprising an inner barrel, an outer barrel rotatable relative to said inner barrel,-a headon said inner barrel provided with a convex end, and a socket member within said outer barrel including a central body having a concave facefacing said convex end and longitudinal ribs extending laterallyfro m said body to -the wall of said outer barrel to form longitudinal cir-' culation passages therebetween, said ribs extending beyond the concave end of said body and beside said head, and said socket member being longitudinally movable in said outer barrel to follow down against said head.

7. A core drill comprising an inner barrel, an outer barrel rotatable relative to said inner barrel, an extension on the upper end of said inner barrel provided with a blunt head, a socket member Within said outer barrel 10 having a central body portion flanked by longitudinal ribs extending longitudinally' beyond said body portion, said ribs and body portion forming a socket rotatable about said headand adapted to receive longitudinal thrust from said head,

the spaces between said ribs forming circulation passages, and said socket member being longitudinally movable in said outer barrel to follow down against said head. v

In testimony whereof I have signed my name to this specification.

' GEORGE A. MACREADY.

Yes

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