US2837314A - Apparatus for deflecting bore holes - Google Patents

Description

I i L! A. F. PICKARD June 3, 1958 APPARATUS FOR DEFLECTING BORE nouns Filed/Aug. 16, 1954 F/GJ UNIVERSAL Jo/zvr June 3, 1958 A. F. PICKARD APPARATUS FOR DEFLECTING BORE HOLES 2 Sheets-Sheet 2 Filed Aug. 16, 1954 MV/I/ERSAL Jam/r 24 INVENTOR. 4485/? TEp/C/(ARD I MW ATTORNE Y6 States Longyear Company, Minneapolis, Minn., a corporation of Delaware Application August 16, 1954, Serial No. 449,942

6 Claims. (Cl. 2551.6)

This invention relates to the art of well drilling. More particularly, this invention relates to an improved apparatus for deflecting bore holes.

It is the principal object of this invention to provide improved methods and apparatus for deflecting the direction of bore holes. in sub-surface formations.

Another object of this invention is to provide an improved method and apparatus for returning angular bore holes to a more vertical orientation.

It is still another object of this invention to provide an improved method and apparatus for deflecting bore holes in predetermined direction and angles.

A further object of this invention is to provide an improved method and apparatus for deflecting bore holes in sub-surface formations without the use of wedges, whipstocks and the like.

Other objects of this invention will become apparent,

as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

The invention is illustrated with reference to the drawings in which corresponding numerals indicate the same parts and in which:

Figure l is a fragmentary sectional view, which may be alongitudinal section illustrating a sub-surface formation with a normal rotary core bit and a'reaming shell therein at the bottom of a hole produced by the bit;

Figure 2 is a similar View showing in section the appearance of the hole after removal of the core drill and core sample;

Figure 3 is a sectional view of the same bore hole showing the bottom of the hole squared and the apparatus of this invention set in place to begin drilling a pilot hole;

Figure 4 is a sectional View showing the apparatus of this invention in place of the new and deflectedpilot hole;

Figure 5 is a sectional view of the new and deflected bore hole reamed to size;

Figure 6 is a sectional view of a sub-surface formation showing one form of apparatus of this invention, partly in section, in place in the bore hole; and

Figure 7 is a transverse sectional view taken along the line 7-7 and in the direction of the arrows of- Figure 6, but oriented, with relation to the rotation axis differently than in Figure 6.

Referring to the drawings, a sub-surface formation is illustrated at 10 in Figure l and in the remaining figures. The sub-surface formation may be considered as being deep in the rock forming the earths crust and may be considered as being hundreds or thousands of feet from ren t Patented June 3, 1958 "ice the. surface where the drill rig is situated. It is well known, of course, that where drilling is initiated from the surface through the drift or soil overlaying the subsurface rock formations, it is customary to drill through the drift and case the hole thus formed down to rock level with casing of suitable size so as to prevent caving through the overlaying drift. However, deep in the rock formation there is usually no casing, the hole wall being maintained by the strength of the formation itself. Thus, inFigure 1 the drill rod 11 is in the bore hole 12 and at-its lower end may carry a reaming shell at 14 below which there is mounted the usual rotary or core bit 15. Although, illustrated with particular reference to holes drilled with a diamond core drill it is to be understood that the principles of this invention are not so limited but are applicable as well to use in deflectin bore holes, by whatever means made.

Because the bore holes illustrated in the figures of the drawings are of considerable length, they are necessarily broken, as in Figures 3, 4, 5 and 6 in order to show the reference portions of the hole and apparatus in a scale which will be intelligible. Although in sectional view, the sub-surface earth formations have not been hatched since the presence of the oblique parallel cross-hatching lines creates optical illusions which tend to distort or obscure the deviations of the illustrated bore holes and makes more difficult the understanding of the invention. I

At any depth the drill operator can by suitable instruments and methods well known in the art deter-- mine the direction and angle in which the hole is progressing. When it is determined that the direction and angle of the drill hole are not such as is desired and the path of further drilling is desired to be deviated from that shown at 16, the direction of drilling must be corrected. In accordance with this invention such correction of drilling direction and angle is accomplished in a plurality of novel manipulative steps and by the use of novel. combinations of apparatus as follows:

The invention will first be described with reference to deflecting an inclined bore hole to a vertical direction. The fact that the bore hole has deviated from vertical becomes known by means of a survey of the hole for angle and direction (azimuth).

Although members 11 are actually tubes screwed together they are commonly referred to as drill rods and collectively when assembled end to end in a hole as a drill string. This terminology will be used throughout this specification. discussion the drill string may include a core barrel 11a on the end of the lowermost drill rod 11, as is commonly used in exploratory drilling. The entire drill string is provided throughout its length with a central aperture 17 through which drilling fluids under pressure are pumped from the surface for the purpose of lubricating and cooling the bit and carrying cuttings up around the drill string to the surface.

As is well understood in this art, the .drill stringshould be centered in the bore hole at all times in order stabilizers or guides are conventionally used in the Obviously, the diameter of the drill string must be smaller than that of the hole, but otherwise it is inde- For the purpose of this 3 pendent of the diameter of the bore hole and of the diameter of the pilot drill.

As shown in Figure 2, when the drill string with the core bit is removed from bore hole 12, the bottom 18 of the bore hole is irregular in contour, usually containing a stump 19 of the core. The :first step .in preparing the hole for deflecting its course isltoasquare or flatten the bottom of the hole by grindin'g it out by well known conventional means and (as-shown-in Figure 3) providing the hole with a new bottom 18A. The core bit 15 and reaming shell 14 are removedfrom the bottom of the drill rod '11 and a deflecting pilot drill 'head is substituted therefor.

The deflecting .pilot drill assembly comprises "a pointed diamond round nose bitZll having a diamond 21 or other hard material point positioned at the apex of the nose to act as-a pivot for the drill. The roundnose drill pilot bit, which is substantially smaller indiameter than the bore hole '12, is mounted on the lower end of an elongated-section of reduced tubular drill rod 22 which is'substantially smaller-in diameter than the bit 20. This thinner drill rod 22 is joined to the core barrel 11a by means of a reducing coupling and universal .joint indicated diagrammatically 'at 24. Fluid channel 17 extends down to the :pilot drill bit and terminates in one or more :generally'transversefluid ejection-ports 25 in .onesideofthe bit=above the pivot diamond.

The following dimensions are illustrative of the relative proportions'of the several elements of drilling equipment. given by way of example only and do not constitutea limitation upon the invention. Where the drill string is comprised of size N drill rods 11 and size NX core barrel 11a on the lowest rod 11 the drill rod 22 maybe size E, 5 to6 feet in length. It may be explainedat this point that N, EQNX, EX, etc. are designations of the Diamond Core Drill -Mannfacturers Association covering dimensional standards of bits, drill rod and casing. The standards are based on "a series of four nesting casings corresponding to which are four sizes of bits, casing and drill rods. 'NX bits and N drill rods will pass through NX casing and will=drill a hole large enough to admit 'BX casing, through which, in turn, a BX bit and B drillrod will pass and drill a hole large enou'ghto admit AX casing,'and--so" on. For convenience represent- 1 ative dimensions aretabulated below:

Casing Bit-O. D. Rod-O. D.

"o. n. I.D.

Inches Indies Inches EX 1 4e 1% 1%6 AX an 1 its BX 2% 2% 1 952 NX ass 3 i 2% The reduced diameter ofthe extension-drill rod permits directing the-roundnoseibit in a more vertical direction and allows clearance around the point of juncture of the two holes'as the smaller -bit advances.

After the bottom of the normal-bore hole12=has'= been squared 'orflattened the deflecting-drill assembly is gently lowered to thebottom of the hole and thehole is fluShed thoroughly to remove any-cuttings whichomayi be prescut. The drilling'fluid -is then shut off and=the drill string is then lifted from theybottom of theholea-short distance, for example, onefoot or more, and-allowedto hang suspended for a short time-until the pressure of the fluidin the drill string has equalized with-the -fluidin the bore hole. Normally, this will not take more-than one or two minutes.

The drill string is then again lowered untilnthe bit touches bottom and several hundred pounds pressure is applied on the bit to seat'the' pivot diamond" of the bit. Because of the 'reduced diameter of'the lower elid ofithe his to be understood, however, that they are string the universal joint 24 permits the deflecting bit .to orient itself .at .the lowest point in the bore hole.

That is, under the effects of gravity the lower end of the drill string tends to bow directing the bit vertically downwardly. In the bore hole illustrated in the drawings the low part of the hole is on the right hand side. The pilot bit will seek out and-seat itself at this point generally as shown in Figure 3.

The drilling fluid .is again turned on and drilling is resumed. Because of the seating of the bit on its diamond tip under;pressure the bit pivots on this point and begins drilling a hole in the general direction of the desired path indicated at 27. Without the pivoting axis provided -by the diamond'tip of the bit, the bit would tend to walk around thebottom of the hole so that the point at which it would seat itself and begin drilling could not be predicted.

Drilling with the round nose pilot bit is continued until the new smaller diameter pilot bore hole 28 approachesa idepth corresponding to the length of the extension drill rod 22, as shown in Figure 4. At this POlBLQWhlCh Will-bdOflhfi order of 4 to 5 feet in the case of lt he exemplary dimensions) before the drill string begins to bindin the smaller hole, the drill string is pulled 'a-n'd the pilot hole'is surveyed for angle and direction. The 'courseof'the pilot hole will not immediately assume the desired vertical direction but will be bowed lou't wa'rdly slightly from the direction of the former more gradually assuming the new vertical direction. If the angle and direction of the pilot hole are wron g the hole is reamed'to original size, flattened and the deflectingcycle to this point is repeated. On the other hand 'if the-course of the pilot hole is as planned and desired, then another section of small diameter drill rod isjinserted'in the lower end of the drill string and further drilling of the pilot hole is continued. It may be -pre'ferre'd at this point to remove the round nose bit andsubstitute in its place a conventional core bit or other bit er corresponding diameter. In the exemplary situation an size bit may be substituted 'for the two inch round'nose bit and the small hole may be advanced along the=same-path 29 to a further depth of the order of about six additional feet. The-hole is then reamed to original size 30 to the bottom, in the case of the example to NX size.

Depending upon the extent of the original angular deviation of bore hole 12 one cycle of the deflecting method may be sufficient to return the course of the bore hole to the desired true vertical direction. However, becauseit'is possible to change-the direction of the hole only a few degrees in this relatively short distance, if the angular deviation is great it may be necessary to repeat the process as described above several times before the desired deflection is attained, beginning from the new bottom 31 of the hole. In the case of the cited example using an AX pilot hole about 10 feet in depth in an NX bore "hole the maximum angular deflection that would normally be attained is about one degree. Greater deflection can be obtained in larger diameter holes.

The apparatus and procedures of this invention may likewise be utilized to deflect a bore hole in a predetermined direction. For example, a hole drilleddeep into the crust of the earth, intended to follow a north-northwesterly course at an angle five degrees from the vertical, may'be surveyed and found to be following a course northward from the well head. In order to return the course of hole to the desired direction it is necessary that the direction of the hole he deflected Westward. This maybe done in one of two ways, by orienting the ejection port 25 deflecting drill 20 with reference to an index point on the surface or by orientingthe ejection port 25 deflecting drill 20 with reference to an off-center weighted member 34 at the bottom of the hole (see Figs. 6 and 7).

'In' the first of these methods the roundnose pilot drill bit may be oriented with reference to an index point at the surface by means well known in this art. For example, an index mark may be placed on each section of drill rod 11 as it is attached to the drill string with reference to the master index point at the surface and the index marks on each preceding lower drill rod 11. The position of the index mark on the section of drill rod 11 nearest the bottom of the hole with respect to the index point at the surface can readily be determined. Knowing this, the extension drill rod 22 and the pilot drill bit 24 are assembled for mounting on the bottom of the drill string. A round nose pilot bit 20 having a single, generally transverse water ejection port is used and is oriented so that the ejection port 25 will be opposite from the direction of the desired deflected hole. In the example cited, since it is desired to deflect the course of the hole westward, the bit 20 is oriented with its fluid port directed eastward.

After the bottom of the hole has been reamed flat the drill string with the oriented bit is lowered into the hole. The drilling fluid is turned on and the hole is cleaned by flushing. The drill string is lifted momentarily and then lowered. At the bottom of the hole the force-of the jet of drilling fluid being ejected from the port 25 pushes the round nose pilot bit 20 to the opposite side of the hole. In this instance, since the fluid port is oriented east the bit is forced westward, the direction of the desired deflection. The bit, while so held, is lowered into engagement with the bottom 18a of the hole 12 and the pivot diamond is seated to hold the bit 20 from moving transversely, and drilling of the deflected pilot hole begins as described above.

Alternatively, the pilot bit is oriented with respect to a weighted member at the bottom of the hole. In this form of the invention the drill string is provided at its lower end with an elongated thickened tubular section weighted on one side and adapted to hang freely at the bottom of the hole so that the weighted side of .the section can seek out and come to rest on the low side of the hole. One form of such apparatus is shown generally in Figures 6 and 7. The lower extension of the drill string comprises the round nosed pilot drill bit 20 with a single generally transverse water port 25, threaded onto a drill rod 22 of lesser diameter than the remainder of the drill string 11 and a reducing coupling and universal joint 24 are as previously described. This pilot drill extension assembly is joined by means of a rigid coupling 33 between the off-center weighted section 34 and coupling 24. This section comprises a length of tubular drill rod 35 weighted on one side with lead 36 or other suitable heavy substance cast or otherwise inserted and held in the rod to make one side substantially heavier than the other so that under the effects of gravity this heavy side will lie lowermost in an inclined hole. The unfilled space 37 on the opposite or light side of the drill rod forms a channel which maintains direct fluid communication through fluid channel 17 of the entire length of the drill string. The weighted drill rod 34 is affixed to a spline member 38 which has an axial opening therethrough. A tubular shaft 39 is aflixed at its lower end in the axial opening of the spline member 38 and extends upwardly from the spline member. A shaft-suspending coupling 40 is coupled to the lowest rod member 11 and has a cooperating female spline member 41 formed therein to mesh with member 38. Shaft 39 extends through and is slidable and rotatable in the axial opening in'the coupling 40 and has a bearing structure 42 on the upper end thereof. The sliding movement of the shaft 39 and spline member 38 is limited by a retaining nut 44 locked on the threaded end of shaft 39.

The length of the shaft 39 is suflicient that when the drill string is hanging free in the hole 12, that is, with the bit lifted from the bottom surface 18a, the weighted section 34 causes the cooperating male and female spline members 38 and 41 to separate sufficiently to permit free rotation of the weighted member 34, shaft 39, rod 22 and bit 20. This permits the weighted member 34 and bit 20 to rotate by gravity to a predetermined orientation. Thus, by properly orienting the fluid port 25 of the pilot bit 20 in relation to weight 36 before lowering it into the hole by means of the shim washers 32, the pilot drill bit 20 will be properly oriented so that the pilot .hole will be deflected in the predetermined direction.

respect to the weighted member 34 at the bottom of the hole, the hole after being surveyed to determine angle and azimuth is flattened at the bottom. Since the direction of the bottom of the hole is known (north in the assumed example) and it is known that the heavy side 36 of the weighted member 34 will lie adjacent the lower side of the hole (south in this instance), the round nose pilot,

bit is oriented so that the water port 25 opens outwardly in an easterly direction, or opposite to the direction in which the hole is to be deflected (west). The assembled drill string containing the-weighted section 34 and bit 20 is then lowered to the bottom of the hole and the bottom is cleaned by flushing thoroughly. While flushing the drill string is raised and lowered sufficiently to just lift the round nosed pilot bit a few inches off the surface of the bottom of the hole. This necessarily requires additional lifting of the upper part of the drill string so as to permit relative sliding movement of the lower drill string (including the weighted section 34 and pilot drill assembly) with respect to the remainder of the string. The lower end of the drill string is then free to rotate on its bearing 42 independently of the remainder of the drill string. The dynamic friction produced by the slight raising and lowering of the drill string in the drilling fluid permits the heavy side 36 of the weighted section 34 of drill rod to be oriented adjacent the low wall of the bore hole, in the instance of the example with its index true south. At the same time the action of the jet of fluid from the fluid port 25 in the side of the bit 20 forces the bit to the opposite side wall hole. The bit 20 is lowered to seat the diamond 21 which prevents transverse movement of the bit 20. In the case of the splined apparatus the drill string is simply lowered until the upper spline member 41 seats upon the lower spline member 38. Since the teeth of the spline are fine, any turning of the weighted section 34 and bit 20 during seating of the spline will be minimized. After the bit is seated on its pivot diamond, drilling of the deflected pilot hole is begun as described heretofore.

Throughout the foregoing description of the invention it has been assumed that the bore hole deflection has been started from the natural bottom of a hole. It is to be understood, however, that the driller may always back up and cement a plug in a hole at any desired level and then using that plug as a bottom carry on the operation of the invention as described. Hence the bottom 18A of the hole in Figures 3, 4, 5 and 6 may be considered as a natural formation or as a plug cemented-in at a desired level.

It is apparent that many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, the specific embodiments described are given by way of example only, and the invention is limited only by terms of the appended claims.

What I claim is:

1. Apparatus for deflecting bore holes of predetermined 75 diameter adaptedto. be mounted on the lower end of a drill string, said apparatus comprising a pilot bit having a diameter substantially smaller than the predetermined diameter of the bore hole, said bit being carried by a section of drill rod having a diameter substantially smaller than the pilot bit, a hard pivot point centrally positioned in the nose of said hit, an off-center fiuid ejection port in the side wall of said bit, another section of drill rod having one side thereof weighted, universal coupling means for coupling said smaller drill rod to the weighted drill rod section whereby to permit transverse movement of the bit relative to the bore hole, and means for coupling said weight ed drill rod section to said drill string, said weighted drill rod section being mounted for free rotary and limited sliding movement with respect to said drill string, means for engaging said weighted drill rod section for rotary movement with the drill string and a fluid channel running longitudinally through said coupling means, drill rod sections and bit communicating with said ejection port.

2. Apparatus according to claim 1 further characterized in that said pilot bit is a round nose diamond bit and said hard mineral pivot point is diamond.

3. Apparatus according to claim 1 further characterized in that the means for mounting said weighted drill rod section for free rotary and limited sliding movement comprises a tubular shaft, a hanging coupling on the drill string and having an axial opening therein, a tubular shaft slidably and rotatably received in the opening, retaining means for limiting sliding movement of said shaft, a hearing on said shaft between the coupling and retaining means, and engaging means on said coupling and adapted to. seat in axial movement with cooperating engaging means on the weighted drill rod section for imparting rotarymovement of the drill string to the Weighted drill rod section.

4. Apparatus according to claim 3 further characterized in that said engaging means comprise spline members.

5. Apparatus for deflecting bore holes of predetermined diameter adapted to be mounted on the lower end of a drill string, said apparatus comprising: a round nose diamond pilot bit having a diameter substantially smaller than the predetermined diameter of the bore hole carried by a section of drill rod having a diameter substantially smaller than the pilot bit; a diamond pivot point centrally positioned in the nose of said bit and an off-center fluid ejection port in the side wall of said bit; another section of drill rod having one side thereof weighted; a universal joint coupling said smaller drill rod to the weighted drill rod section; means for mounting said weighted drill rod section to the drill string for free rotary and limited sliding movement with respect to said drill string, said means comprising a coupling on the drill string and having an a rial opening therein, a tubular shaft slidably and rotatably received in the opening, retaining means for limiting sliding movement of the shaft and a bearing on said shaft between the coupling and retaining means; said shaft being atiixed to the weighted drill rod section; key means on said coupling and cooperating key means on said weighted drill rod section forimparting rotary movement of the drill string to the weighted drill rod section; and a liuid channel running longitudinally through said coupling means, drill rod sections and bit communicating with the ejection port in said bit and providing direct fluid communication with s aid'drill string.

6. Apparatus according to claim 5 further characterized inthat'sa'id cooperating key means comprise spline members.

Referencesifited in the file of this patent UNITED STATES PATENTS 92,014 Case June 29, 1869 134,506 Ball Jan. 7, 1873 1,902,174 Lewis Mar. 21, 1933 2,167,194 Anderson July 25, 1939 2,173,309 Monroe Sept. 19, 1939 ENTTEE STATES PATENT OFFICE QETTFTQATE OF CORRECTION Patent Nox 2,831,314 June 3, 1958;

Albert FD Pickard It is hereby certified that error appears in the printed specificatio of the above numbered patent requiring correction and that the said Letter Patent should read as corrected below.

, Column 3 line 62 for "deflecting" read deflecting column 5 line 23;, for "lowered read m relowered Signed and sealed this 16th day of September 1958.,

UZBSIZ KARL Ho AXLINE I ROBERT C. WATSON Attesting Oflicer Commissioner of Paten-

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