US 2533257 A
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I Dec, 12, 1950 H. B. WOODS ETAL DRILL CUTTER 3 Sheets-Sheet 1 Filed June 2, 1945 VENTORS BY Wax/ll) ATTORNEY Dec. 12, 1950 H. B. woons ETAL DRILL CUTTER 3 Sheets-Sheet 2 Filed June 2, 1945 AUGKEEK Dec: 12 3.950
HEM/000s FLSCOTT INVENTORS BY flak fiq'flada.
31 10 ENE,
Patented Deco 12, 1950 DRILL CUTTER Henry B. Woods and Floyd L. Scott, Houston,
Tex., assignors to Hughes Tool Company, Houston, Tex., a corporation of Delaware Application June 2, 1945, Serial No. 597,304
Our invention relates to drill cutters for use in the drilling of wells for oil, gas and the like.
In the drilling of Wells, which sometimes are of great depths-such as, ten or fifteen thousand feetby the rotary method, there are used rotary drills provided with cutters of general conical shape which are rotatably mounted. Such drills are fastened to the lower end of a hollow drill stem which is rotated by suitable mechanism at the surface. The cutters roll upon the bottom of the hole as the drillstem is revolved, and disintegrate the materials to be removed. Such roller cutters are provided with teeth which are forced to penetrate the well bottom by weight of the drill stem, the same being controllable by the operators.
The disintegrated materials from the sides and the bottom of the hole are removed by a fluid which is pumped from the surface through the hollow drill stem, and are carried to the top and removed. The fluid not only thus serves such purposes, but it also cleans and cools the cutters.
7 The form of the teeth and the arrangement of the same upon the cones are of great importance. It is desirable, as far as may be, to provide and arrange a cutting structure that will Work well in a plurality of different formations so as to minimize the necessity of withdrawing the drill before it has exhausted its usefulness, in order to meet the requirements of varying formations.
Some of the very hard formations that must be drilledsuch as quartzite, hard sandy dolomite, or dolomite with chert or flint concretions encountered in formations of the Paleozoic erahave high compressive strength; also, in the main, they are very abrasive. To drill such hard abrasive formations requires the application of unusually heavy weight upon the drill to accomplish a satisfactory rate of penetration as well as to secure a maximum footage per bit.
As the usual type of pyramidal teeth upon the cutters of the drill become worn, the area of contact of the dulled teeth on the formation increases to such an extent as to require the application of increasing weight on the drill that may easily extend beyond the capacity of present-day drilling equipment. In some instances, it has been found that as much as fifty thousand pounds Weight must be applied to a dull 8%," diameter bit to secure practical drillin results. Since there are obvious limits to the strength of the parts of the drill, there is, therefore, a need for a cutting structure on the substantially conical cutters which will permit of a satisfactory rate oi drilling with a medium weight such as 20,000#
to 30,000# supplied by suitable drill collars so that said cutting structure will continue to function well until it has been practically worn away in service. To this end, it is desirable to provide a cutting structure not easily broken and one that requires a minimum of weight upon the drill as the teeth of the cutters become dulled or shortened in operation. To accomplish these results, we have provided in our invention a strong cutting structure such that as the cutting elements are worn off, their area of contact on the well bottom will not greatly increase.
An object of the invention is to provide a circular, fiat-crested cutting element for the coneshaped cutters, the crest area of which will not rapidly increase as the cutting element wears, so that the bit will maintain a desirable rate of penetration throughout the life of the cutters without necessity of unduly increasing applied weight.
Another object of the invention is to provide an outer row of longitudinal teeth in combination with a plurality of inner, circumferential rows of flat-crested cutting elements, the said outer row or rows to assist in the rotation of the cutters.
A third object is to provide a set of generally cone-shaped cutters havin strong, segmental, flat-crested, circumferentially arranged cutting elements spaced longitudinally of one of said cutters, the sum of the crest lengths of the segments in any row being less than the full circumference of said row, so that lower initial weight will be required to make said cutting elements penetrate the formation for more rap-id excavation of the material to be drilled.
Another object of the invention is to provide a set of generally cone-shaped cutters having segmental, flat-crested, circumferentially extending cutting elements spaced longitudinally of said cutters, with such elements on adjacent rows staggered longitudinally, while the cutting elements on each of said cutters are staggered circumferentially so that as the cutters rotate, the Weight will not only be better distributed around each cutter as it rolls on the well bottom, but said weight will be more evenly distributed between companion cutters of the set for better traction and prevention of intermittent overloading.
Another object is to provide a plurality of longitudinal cutter teeth upon a cone cutter with a web joining one end of each tooth with the adjacent tooth on one side and with another web extending from the opposite end of the" same tooth to the next adjacent tooth on the opposite side to crush the ends of the rock teeth formed in the bottom of the hole by said longitudinal teeth. 7
Another object is to space widely the segmental, flat-crested, circumferentially extending cutting elements upon the cone to facilitate cleaning and acting together with adjacent cones, to cut the full well bottom.
Other and further objectives of our invention will readily appear when the following description is considered in connection with the accompanying drawings wherein:
Fig. 1 is a perspective view looking at the bottom of a well drill constructed in accordance with the invention and illustrates the flat-crested segmental circumferential cutting elements.
Fig. 2 is a perspective bottom view of a slightly modified form of the flat-crested circumferential cutting elements where short segments are spaced circumferentially from each other.
Fig. 3 is a perspective bottom view of a slightly modified form of the flat-crested circumferential cutting elements where the element constitutes a continuous circle.
In Fig. 1 the bit bod 2 has the usual threaded shank 3 thereon by which it is connected to the drill collar for rotation, and the cone supporting legs 4 upon which the cones 5 are rotatably mounted.
Three cones have been illustrated as being rotatable to perform the cutting action. These cones are usually designated as the No. 1 cone, which would be the cone '5; the cone 8 would be the No. 3 cone, while the cone 9 would be the No. 2 cone. These cones are usually so numbered because of the fact that the No. 1 cone has the most inwardly disposed or the smallest diameter cutting structure, the No. 2 cone has the next larger diameter cutting structure at its inner end, while the No. 3 cone has the third larger diameter cutting structure at its inner end. Such arrangement is provided where the teeth are interfitting longitudinally of the cone.
In describing the No. 1 cone, Fig. 1, which is the cone 1, the cone body is conical in shape and has an outer row of longitudinal teeth I I spaced therearound. The outer ends ii of these teeth are joined by a connecting web it. The purpose of the webs I3 is to trim down the rock teeth which tend to form at the junction of the bottom and wall of the hole. The cutting away of these rock teeth reduces wear on the outer ends of the longitudinal teeth 92 and in this manner maintains the gauge of the hole being drilled. One form of such web is shown in the prior patent to Scott, No. 2,363,202, issued November 21, 1944.
Disposed inwardly of these longitudinal teeth are a plurality of rows of circumferential flatcrested cutting elements or projections. The outermost row !5 of such elements is made up of a single circumferential element 56, which is substantially less than an entire circle, and in the drawing may constitute about one-third of a circle. The next inwardly arranged element I! also comprises about one-third of a circle or less than half a circle, and is arranged. to begin at about where the element i5 terminates. The third inner element is is similarly arranged to begin at about the end of the cutting element 11 and to continue for about one-third of a circle to terminate opposite the end of initial element [5.
The arrangement of these elements may be described by stating that they are staggered longitudinally of the cone 1 as well as being staggered circumferentially of the cone.
The particular structure of the ridge-like cutting element is such that the base portion 20 merges into the surface [9 of the cone and the body 21 of the element projects substantially at right angles to the surface of the cone. The outside face 22 and the inside face 23 have been illustrated as slightly tapering toward each other so that they are joined by the crest 24. The sides are not necessarily so tapered, however. The crest 24 may be a flat crest and may have rounded corners joining the side faces.
For example, the width of the flat crest may approximate of an inch. For hard rock such a cutting element has been found to be more efficient than the pyramidal tooth structure disclosed in Patent No. 1,647,753, to Scott, issued November 1, 1927, because of the greatly reduced area of cutting surface allowed to contact the well bottom as the ridges wear down.
The No. 1 cone, 1, has the nose cutting structure 26, which may include the annular notched circular cutter portion 2'. and the spear point 28 so as to knock out any core or pedestal which would tend to form were the spear point not there.
The No. 3 cone shown at 8 is similarly formed except that there is no spear point and the outer row of teeth H is slightly modified so that there is an inner web 3| joining the inner ends of two adjacent longitudinal teeth I I. On the other end the opposite flanks of the teeth H are joined to the next adjacent teeth by the outer Webs I3. This arrangement leaves an internal pocket 35 between two adjacent teeth while an external pocket 36 is arranged between the next two adjacent teeth.
The inside web 3| tends to reinforce the inner extremities of the longitudinal teeth and crushes the ends of rock teeth that may be generated on the well bottom. This cutting off of the ends of the rock teeth also assists the next inner row of cutting elements because the rock teeth are destroyed in that region. This same action occurs at the periphery of the hole due to the outer web [3 and in addition prevent ridges on the wall of the hole. The wide spacing of the circumferential cutting elements and the interrupted areas tend to maintain the cone clean and prevent balling up.
The No. 2 cone, designated as 9 in the drawing, is formed with the circumferential elements I 6, I! and [8, as heretofore described, but has a slightly modified arrangement of the longitudinal teeth II, in that they are somewhat longer than the teeth II of the cone 1. Each tooth l l on cone 9 is provided with a recessed area 40 to allow clearance for the inner ends of teeth II on cone 8. The inner webs 3| and the outer webs I2 are the same as previously described in connection with the cone 8. The slight extension 45 of the webs l2 on the outer ends of the teeth ll may be provided so as to form a relatively narrow slot 46 as defining the outer pocket 36. Thi structure is of advantage because it makes an overlapping track on the bottom of the hole around the periphery so as to prevent the formation of rock teeth. These extensions provide additional area for deposition of tungsten carbide to help maintain the gauge of the hole.
It should be borne in mind that all the rock encountered is not of the same hardness; that the rock is stratified in harder and softer areas so that in some instances, due to the weight on the bit, the cones may have a tendency to slide on bottom rather than to roll. The longitudinal teeth I I provide traction to discourage such sliding, particularly when a softer rock formation is encountered.
Broadly the invention contemplates an arrangement of relatively narrow circumferential flat-crested segmental ridge-like cuttin elements on the rotating cone; the combination therewith of the circumferentially webbed cutters for the outer row; and also the combination of the inside and outside alternate webbed portions.
Fig. 2 shows a slightly modified form of the construction where the outer rows of teeth on the cones l, 8 and 9 are the same as previously described, but the circumferential segmental ridges l5, 16, I1, and E8 of Fig. 1' have been modified so that they form the circular rows 50, 5| and 52. These circular rows are each made up of a plurality of short segments or projections 53, which are similar to the segmental teeth l5 of Fig. 1, except that the segments are much shorter and spaced apart by the openings 54. Of course, the rows on the No. 1, No. 2, and No. 3 cones are offset relative to each other so as to permit interfitting.
Fig. 3 shows another slightly modified form of the arrangement wherein the outer teeth are the same as previously described but the circumferential ridges l5, l6, l1 and 18 of Fig. 1 are in the form of complete circles 6|, 62, 63, as best seen on the No. 1 cone of Fig. 3. These ridges on the several cones are also interfitting. Such arrangement permits cleaning of adjacent cones, and allows greater height of the cutting elements which in turn renders a greater cutting life. An advantage of the circumferential cutting elements resides in the fact that the elements do not appreciably increase in crest area as they wear down and consequently cut at a rate approaching their rate of cutting when new.
Broadly the invention contemplates a combination of cutter teeth for rotary cone well drilling wherein longitudinal and circumferential teeth are provided, where such teeth may be 6 complete circles, or different length segments thereof.
What is claimed is:
1. A cone type well drill including a head having mounted thereon a plurality of cones to roll upon and disintegrate the well bottom, a plurality of completely circular independent cut ting elements having continuous annular crests spaced longitudinally of at least one of the cones, each cutting element including a body portion projecting at substantially right angles from the cone surface and having slightly tapered side surfaces joined at their outer ends by the continuous annular crest.
2. A cone type well drill including a head, three roller cones mounted thereon to roll upon and disintegrate the well bottom, a plurality of completely circular independent cutting elements having continuous annular crests and spaced longitudinally of at least one of the cones, each cutting element including a bottom portion projecting from the cone, the circular cutting elements of each cone being offset with respect to the cutting elements of the adjacent cones and spaced along the surface so that each cutting element inter-fits between cuttin elements of each adjacent cone and together the cutting elements on the cones cut the entire bottom of the well.
HENRY B. WOODS. FLOYD'L. SCOTT.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,896,251 Scott Feb. 7, 1933 1,918,902 Fletcher et al July 18, 1933 2,027,700 Rogatz Jan, 14, 1936 2,151,348 Fisher Mar. 21, 1939 2,176,358 Pearce Oct. 1'7, 1939 2,177,332 Reed Oct. 24, 1939 2,228,286 Ross Jan. 14, 1941 2,294,544 Garfield Sept. 1, 1942 2,333,746 Scott et a1 Nov. 9, 1943 2,363,202 Scott Nov. 21, 1944