US2838286A

US2838286A - Rotary drill bit

Info

Publication number: US2838286A
Application number: US579299A
Authority: US
Inventors: Benjamin L Austin
Original assignee: Christensen Diamond Products Co
Current assignee: Norton Christensen Inc
Priority date: 1956-04-19
Filing date: 1956-04-19
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

June 10, 1958 B. L AUSTIN 2,833,285

ROTARY DRILL BIT Filed April 19, 1956 2 Sheets-Sheet;

BEAM/7mm L. flusrnv,

INVENTOR.

June 10, 1958' B. AUSTIN 2,838,286

ROTARY DRILL BIT Filed April 19, 1956 Y I 2 Sheets-Sheet 2 BENJAM/A/ L. Hus

' INVENTU the hole bottom 1 cutting face selves,

nited States 2,838,286 RQTARY DRILL BIT Benjamin Austin, Ogden, Utah, assignor to Christensen Diamond Products Company, Salt Lake City, Utah, a corporation of Utah Application April 19, 1956, Serial No. 579,299

8 (Claims. (Cl. 255-72) embedded therein, and to cool such faces and diamonds.

Heretofore, the aforementioned intended purposes have not been accomplished efficiently. The cutting faces and the diamonds embedded therein have not beencl'ea'ned properly, reducing the penetration rateof the diamonds in the formation. Reduction of penetration rate is attributable to some extent to the operation of the diamonds upon previously made cuttings remaining between the diamonds and undisturbed formation. It is also caused by the packing of the cuttings between the diamonds, preventing the latter from contacting the .bottom of the hole. Instead, thecuttings packed on the bit skid or slide along the hole bottom, generating a large amount of heat which may be sufficient to melt or burn a portion of the matrix material in which the diamonds are held, with consequent dropping out or loss of some diamonds from the bit. Substantial generation of heat will occur, since the inability of the circulation fluid to cleanthe drill bit also militates against its cooling the bit, for the reason 'that the packed. cuttings prevent the fluid from fiowing'across the bit faces andthe diamonds themselves.

Attempts have been made to clean and cool the bit by providing grooves or watercourses in 'thecutting faces of the bit, through which. circulation fluidwill flow.

The cutting facesgand, diamonds adjacent: the watercourses there .willbe more. diamonds around the outer portion of H thanaround the inner .portion f such, cutting face. The watercourses, however,

-have ;l1 eretofore been much furthergap'artat the outer portionof the cutting facefthan at"itslinner portion, re-

- sulting in the la'cl'c of .pr'oper'cleaiiing oflthe. cutting faces and, diamonds at. the outer'portion ofth bit, except, possibly, immediately adjacent the watercourses them- Accordingly, itjis an'object of the' present invention to .impr'ovedrotaify' drill bit havinga diamond provide an studded drilling face, which can be maintained in a clean and. cool'fs'tate by'th'e circulating 'fiui'd during the drilling of aihole'infthe formation, thereby enhancing the penetra'ti'oh rate of the bit and increasing its useful life.

Another objectof the inventionis to-provide-a rotary diamond drill bit having watercourses in its; cuttingface arranged in such manner as .to cause the circulating fluid .to flow from one watercourse to another across the diamond studded cutting face, cleaning and cooling all portions of the latter., The outer portionsof the cutting face are cleaned and cooled as effectively as its inner portions.

A further object of the invention is to provide. a rotary diamond drillv bit embodying watercourses that are-spaced apart by substantially uniform and-relatively short'distances across the entire bottom'hole contactingface or faces of the bit, to insure circulation of the drilling fluid across all portions of such contacting face or faces and their-maintenancein a clean 8.1'1d1C00l condition.

An additional object-of the; invention .is to provide a rotary diamond drill bit having watercourses-in its cutting face or faces arranged in 'such manner as to result in a substantially uniform concentration ofdiamonds on its cutting face or faces between the watercourses per unit of projected area, and an'eflective cleaning and cooling of all areas of such cutting face or faces. The

outer'portions'of the cutting face or faces are cleaned as effectively 'as the inner portions.

Still a further object of the invention is to provide ta rotary diamond drill bitembodying watercourses spaced from one another by relatively short distances to"pro viderelatively narrow spans or lands between watercourses in which the diamonds are held, the watercourses being so arranged that circulating fluidnot only travels through the watercourse s, but also flows between watercourses and across the lands to clean andtcool them.

parentfrorn a consideration-of a form in which it may beembodied. This-form is shown in the drawings-accompanying and forming part of the present specification; It will now be described in detail, for'the purpose of illustrating the general principles of the invention; but it :is to be understood that such detaile'ddescription is not to be taken in a limiting sense, since the scope of the inventionis best defined by the appended claims. Referring to the drawings: 7

' Figure 1 is a combined side elevational and longitudinal section of a rotary core drilling bit embodying the invention; 7 p v 'Fig. 2 is a cross-section taken along the line 2-2 on Fig. l; p

Fig. 3 is .afragmentary bottom plan view of the .bit disclosed in Fig. l;

5 ig. 4.is .an enlarged view similar to Fig. 3;

Fig. 15 is a section taken alongtheline 5-5 on Fig. 3.

The invention is illustrated .in the drawings as being applied to acore bit, which may form the, lower portion of an apparatus for taking a core smple, the core passingupwardlyinto a core barrel (not shown) in aknown manner. it .is to be understood, however, that in its broader. aspects, the invention is notlimited to core bits, but is directed to rotary drill bits generally.

' As, disclosed in the drawings, the apparatus includes a tubular, main bit body or shank lllhaving an upper threaded box 11 threadedly secured, onto the lower threaded-pin 12 of a tubular drill collar or drill pipe 13 forming the lower end ofa drill string extending to the hasamatrix 17 of-relativelyhard material, of any suitable type, secured to its outer, bottom, and inner surfaces, in which diamonds 18 of the proper size are secured in a known manner. These. diamonds may project from the surface of the matrix 17 to the extent desired, or some of them may be flush with the surface. They are arranged in a desirable pattern on the exposed

faces

14, 15, 16 of the matrix, to operate upon the bottom and sides of the hole being drilled.

Circulating fluid, such as drilling mud, is pumped down the drill string 13 during the rotation of the apparatus, this drilling fluid passing through relatively shallow longitudinal grooves or recesses 19 in the inner wall of the bit body and around the core barrel (not shown), the drilling fluid discharging through the throat of the bit and onto the bottom of the hole. The drilling fluid will also flow outwardly along the bottom of the hole, to clean the hole of cuttings and carry them around the outside of the bit and the drill string to the top of the hole, all generally in a known manner.

As specifically disclosed, the drill bit is provided with a convex bottom portion 14 merging into an inner surface 15 and also an outer surface 16. Since the bit specifically illustrated is a core bit, the inner surface 15 is substantially cylindrical, which is also true of the outer surface 16 which constitutes the reaming portion of the bit. To enable the bit to drill hard formations, the matrix 17 has the diamonds 18 embedded in the inner, lower and

outer faces

15, 14, 16, these diamonds being arranged in any desired pattern.

For the purpose of cleaning and cooling the cutting surfaces of the bit, a plurality of grooves 21 is formed in such faces in a particular manner, providing watercourses through which the circulating fluid can flow readily from the interior of the bit to the bottom of the hole, and thence outwardly along the bottom of the hole, from where the fluid will flow in an upward direction past the reaming face 16. The grooves 21 are relatively shallow, and are substantially equally spaced from each other around the cutting faces of the bit to provide spans or lands 22 between the grooves in which the diamonds 18 are embedded. The grooves 21 extend along the inner face 15, around the convex lower face 14, and upwardly along the outer reaming face 16 of the bit. The grooves are separated from one another by relatively short distances to provide relatively short or narrow lands 22 therebetween in which the diamonds are embedded and from which they may project. As shown, the groove portions 21a are substantially parallel to the axis of the bit along the inner cylindrical face 15 of the matrix, the upper ends of these watercourse portions 21a opening into the bore 23 of the bit body or shank, to receive drilling fluid therefrom. The groove portions 21b are arranged in spiral fashion along the convex lower face 14 of the bit, the inner ends of these spiral groove portions merging into the lower ends of the groove portions 210 and their outer ends into inclined groove portions 210 generally parallel to one another and arranged along the gauge or reaming face 16 of the bit. Each groove 21 is continuous beginning at the upper end of the inner cylindrical face 15, where it communicates with the main fluid passage 23 in the bit body, and then continuing down along the inner cylindrical facelS and into the convex face 14, where the groove portion 21b is arranged in a spiral manner (at an increasingly greater angle with respect to a radial line drawn from the axis of the bit to the commencement of the spiral) outwardly toward the reaming face 16 of the bit, the groove then continuing as the inclined portion 21c, as disclosed most clearly in Fig. l, to the upper end of the reaming face 16, where the groove portion has an outlet into the well bore around the bit body 10. The inclined groove portion 21c makes a substantial angle to a plane radial of the bit axis.

The grooves 21 are separated from one another by the relatively short lands or spans 22, and are also generally equidistant from one another, the lands each including an inner cylindrical portion 22a, merging into a lower spiral portion 22b (which is also directed at an ever increasing angle to a radius. drawn through the beginning of the spiral portion), the spiral portion of the land running into an inclined land portion 220 between the inclined watercourse portions 21c extending along the outside diameter or reaming face 16 of the bit.

In the use of the apparatus, it is lowered in the well bore to the bottom of the hole, the proper drilling weight being then imposed thereon while the bit is rotating at the proper speed. During the drilling action, circulating fluid, such as drilling mud, is pumped down the string of drill pipe 13, and will pass through the main or central passage 23 in the bit body and the recesses 19 into the watercourses or waterways 21. The fluid passes through the watercourse or groove portions 21a in the interior of the bit and thence through the spiral portions 21b along the bottom contacting face 14 of the bit, then passing upwardly through the inclined watercourse portions 21c in the outer face 16 of the bit into the well bore annulus around the bit body or shank 10. The circulating fluid is pumped through the tool and the watercourses 21 at a proper rate, and will flush the cuttings from the drilling region in an outward direction and up around the bit and the drill string 13 to the top of the well bore.

Not only does the fluid flow through the watercourses or grooves 21 themselves, but it also flows transversely from the waterways across the diamond-studded lands 22 to other waterways in a substantial quantity, removing the cuttings between the diamonds 18 on the lands and cooling the lands. The fluid effectively prevents cuttings from packing between the diamonds 18, which would minimize the extent of penetration of the diamonds into the formation. The effective cleaning and cooling action of the fluid passing across the lands 22 from one waterway to the next waterway is due to the fact that the fluid flowing downwardly through the throat 20 of the bit and its inner waterway portions 21a tends to follow a straight line path and resists attempts to confine it for lateral outward flow along a curved path, such as through the spiral waterway portions 21b. Some of the fluid, therefore, moves out of one waterway 21, and flows across a land 22 to the next adjacent waterway on the opposite side of the land. In flowing across the land, it cleans and cools the face of the land and the diamonds projecting therefrom.

The tendency for the fluid to flow along a straight line path, which, in the present instance is generally radially of the bit in an outward direction is enhanced by the fact that a pressure differential exists between different points of adjacent curved or spiral watercourse portions 21b. Each watercourse or groove portion 21b may be considered as a conduit through which fluid is flowing, since the formation substantially closes its open side. Inasmuch as the watercourse is relatively shallow, and particularly since the circulating fluid is usually a comparatively heavy drilling mud, there will be a progressive pressure drop in each watercourse commencing from its inlet and running to its outlet portion. As shown diagrammatically in Fig. 4, the pressure in a watercourse portion 21b at the point a will be greater than the pressure at the point b, which will be greater than at a point 0 further along the watercourse. In other words, the pressure will progressively decrease along the length of each watercourse. Since the fluid tends to flow along a straight line path, or in a generally radial direcn'on, it will tend to cross a land, travelling from different points in one watercourse portion 21b to the next watercourse portion 21b, reaching the next watercourse portion at greater distances from its inlet a than its points of exit from the first-mentioned watercourse portion.

The following example is given of the foregoing statement, reference being had to Fig. 4. The pressure in a watercourse drops progressively along its length, decreasing pmsre si e at he p in s .a, h corre- 5 ,sponding points in the next watercourse are designated a b 11 ,3 Since the drilling fluid tends to resist following a curving flow path, fluid in one watercourse at point tends to continue movement in a straight line path S across a land 22 to the next watercourse, entering the latter at the point al This point d is at a much greater distance from the entrypoint a of the watercourse than is the point b from the entry a of its Watercourse. Accordingly, in view of the progressive pressure drop along each watercourse, the pressure at point b will be substantially higher than at point d producing a pres sure differential, which induces the fluid to leave one watercourse and flow across the land to the next watercourse. In so flowing across the land, it cleans it of detritus and cools it as well. The fluid from point b not only follows the straight line path S, but also flows more directly across the land, in view of the lesser pressures at other points of the next watercourse. Thus, the pressure at point 0 is less than at point 12, some fluid at the point b flowing along the path T to the point c It is evident that the pressure differentials between the watercourses will produce a general transverse flow across the lands 22 from one watercourse to the other, and such transverse flow coupled with flow of fluid through the watercourses themselves, will thoroughly clean the bottom of the hole of the cuttings, completely flushing such cuttings from each land and insuring its maintenance in a clean and a cool condition.

It is to be noted that the distance between watercourse portions 215 is very little greater at the outer region of the bit bottom than, at its inner region. The lands 22b themselves are of substantially uniform width, possibl being only slightly wider at their outer regions than at their. inner regions. The spiral arrangement of watercourses or grooves 21b results in such substantial uniformity of widths oflands ZZband of watercourses 21!) across. the bottom face of the bit. It also results in theability to concentrate diamonds across thebottorn *face of the bit insuch manner that'they are uniformly disposed per unit or square inch of projected area, the substantially uniform disposition and concentration of diamonds being maintained from the inside diameterof the bit to the outside diameter or reaming face 16 of the bit. Such substantially uniform concentration of diamonds per unit of projected area equalizes the work which'is done by each diamond or stone onthe face of the bit, inasmuch as there are obviously more diamonds availablefor cutting action at the, outer portion of the bottom cutting face 14 than at the inner portion. The general uniformity of disposition of the stones 18 on the faceof the bit perunit-of prQjecte'darea insures -a more uniform rate of wear of the diamond stones, and results in a greatly increased life of the drill bit.

It is evident that the spiral fluid course pattern, which produces the spiral lands 22 containing the diamonds,

provides a substantially uniform concentration of diamonds from the inside of the bit to its outside diameter without substantially Widening the lands adjacent the outside diameter of the bit, which would have the drawbac; of the watercourses 21 being widely separated, di-

minishing the flushing action of the circulating fluid across the lands or spans 22 etween watercourses at the outer portion of the bit.

it is, accordingly, apparent that a rotary diamond drill bit has been provided, in which the bit is maintained in a clean and cool condition by the circulating fluid, assurance being had that all cutting faces of the bit will be thoroughly flushed by the drilling fluid. The fluid does not only flow through the watercourses, but also transversely from one watercourse across a land to an adjacent watercourse throughout the length of the land, and, in so doing, insures the maintenance of all surfaces of the lane face in a clean and cool. condition. Accordingly, there is no localized burning of land areas, particularly in regions that are not immediately adjacent the watercourses themselves. A proper concentration of diamonds is secured across the cutting faces of the bit, there being more diamonds around the cutting faces adjacent the outside or reaming portions of the bit than on the inside, which, of course, is desirable since the circumference traversed by the outer portions of the bit during each revolution is much greater than the circumference covered by the inner portion of the bit, the outer portion being required to remove more formation than inner portion and being subjected to a greater total amount of work.

The inclination of the watercourse portions 210 along the reaming face 16 of the bit also results in aproper cleaning and cooling of such reaming face, since the fluid will not all remain in the inclined watercourses, but will tend to move in a direction generally parallel to the axis of the bit, flowing from one waterway, across the inclined reaming lands 22c, and into the next waterway. In so flowing across the land 220, it cleans and cools the latter.

The inventor claims:

1. In a rotary drill bit: a body having a drilling face adapted to engage the bottom of the hole in which the bit is operating and a fluid passage extending longitudinally therethrough and opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced generally'spiral watercourses to provide substantially uniformly spaced generally spiral lands between said watercourses, each land being engageable with the bottom of the hole acrosssubstantially the full width of the land, cutting-elements secured to said lands for operation upon the'bottorn ofthe hole, each of 'said spiral watercourses commencing at said fluid passage and extending laterally outwardly therefrom to the outer portion of said body atan increasing angle to a radial line fromthe body. axis to-thecommencement of said watercourse, the arcuateextent of each watercourse and land around the drilling face being substantially less than 360 degrees.

2. In a rotary; drill bit: abody havingaa drilling face adapted to engage 'thebottom ofthe hole in which'the bit is operating. and a fluid passage extending longitudinally therethrough andopeningainto said drilling ;f'ace, said drilling face containing aplurality of spaced-generally spiral watercourses to provide spaced generally spiral lands betweensaid watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements [secured -to said lands-for-operation upon the bottom of the hole, each of said spiral watercourses commencing at saidfluid passage and extending-laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees.

3. In a rotary drill bit: a body having a drilling face adapted to engage the bottom of the hole in which the bit is operating and a fluid passage extending longitudinally therethrough and opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced generally spiral watercourses to provide substantially uniformly spaced generally spiral lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements secured to said lands for operation upon the bottom of the hole, each of said spiral watercourses commencing at said fluid passage and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees, each watercourse having a substantially 7 uinform width throughout its length, each land having a substantially uniform width throughout its length.

4. In a rotary drill bit: a body having a drilling face adapted to engage the bottom of the hole in which the bit is operating and a fluid passage extending longitudinally therethrough and opening into said drilling face, said drilling face containing a plurality of spaced generally spiral watercourses to provide spaced generally spiral lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements se-' cured to said lands for operation upon the bottom of the hole, each of said spiral watercourses commencing at said fluid passage and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees, each watercourse having a substantially uniform width throughout its length, each land having a substantially uniform width throughout its length.

5. In a rotary drill bit: a body having a drilling face adapted to engage the bottom of a hole in which the bit is operating and a fluid passage extending longitudinally therethrough and opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced smoothly curved watercourses to provide substantially uniformly spaced smoothly curved lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements secured to said lands for operation upon the bottom of the hole, each of said watercourses commencing at said fluid passage and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees.

6. In a rotary drill bit: a body having a drilling face adapted to engage the bottom of a hole in which the bit is operating and a fluid passage extending longitudinally therethrough and opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced smoothly curved watercourses to provide substantially uniformly spaced smoothly curved lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements secured to said lands for operation upon the bottom of the hole, each of said watercourses commencing at said fluid passage and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees, each watercourse having a substantially uniform width throughout its length, each land having a substantially uniform width throughout its length.

7. In a rotary drill bit: a body having a convex drilling face adapted to engage the bottom of a hole in which the bit is operating and fluid passage means extending longitudinally through and opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced generally spiral watercourses to provide substantially uniformly spaced generally spiral lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements secured to said lands for operation upon the bottom of the hole, each of said spiral watercourses commencing at said fluid passage means and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees.

8. In a rotary drill bit: a body having a convex drilling face adapted to engage the bottom of a hole in which the bit is operating and fluid passage means extending longitudinally through an opening into said drilling face, said drilling face containing a plurality of substantially uniformly spaced smoothly curved watercourses to provide substantially uniformly spaced smoothly curved lands between said watercourses, each land being engageable with the bottom of the hole across substantially the full width of the land, cutting elements secured to said lands for operation upon the bottom of the hole, each of said watercourses commencing at said fluid passage means and extending laterally outwardly therefrom to the outer portion of said body at an increasing angle to a radial line from the body axis to the commencement of said watercourse, the arcuate extent of each watercourse and land around the drilling face being substantially less than 360 degrees.

References Cited in the file of this patent UNITED STATES PATENTS 817,296 Besson Apr. 10, 1906 2,381,415 Williams Aug. 7, 1945 2,612,348 Catallo Sept. 30, 1952 FOREIGN PATENTS 979,107 France Apr. 23, 1951