US2998088A - Drill bit - Google Patents

Description

29, 1961 T. PENNINGTON u DRILL BIT med Nov. 2, 1959 FIG. 4

i INVENTOR.

THOMAS PENNINGTON,H,

ATTORNEY.

United States Patent 2,998,088 DRILL BIT Thomas Pennington 1], Houston, Tex., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla., a corporation of Delaware Filed Nov. 2, 1959, Ser. Nb. 850,483 3 Claims. (Cl. 175-329) This invention relates to drill bits, and more particularly to drill bits equipped with cutting elements such as diamonds.

Drill bits utilizing a multiplicity of small, hard, cutting elements, such as diamonds, have been utilized for many years both for hard earth-formationdrilling and for taking cores of earth formations. Prior art diamond drilling bits for these purposes are described in U.S. Patents No. 2,371,488 and No. 2,371,490 to E. B. Williams, Jr.

Manifestly, it is desirable that the drilling life of a bit he as long as is possible. One of the larger expenses entailed in drilling an oil and/or gas well is the cost of round trips for the purpose of replacing worn bits. The cost of a round trip increases tremendously as the well is drilled deeper and deeper into the earth. Furthermore, it is desirable to drill as rapidly as possible while the bit is on the bottom. g

In accordance with one aspect of the invention, a drill bit having cutting elements such as diamonds is formed by affixing a matrix to a bit body so that a drilling face is at the bottom of the bit, and dividing the matrix into an even number of sections by means of water courses. Adjacent sections of the matrix are in stepped relationship; first alternate sections are at one level relative to a second level of second alternate matrix sections. The cutting elements are embedded in the matrix. The distance between the two levels of the faces of the matrix sections is between the drilling length of the cutting elements and half of the drilling length of the elements. The term drilling length, as used herein, means the length of the elements in the direction of a longitudinal axis of the drilling bit.

The invention will be described in greater detail with reference to the accompanying drawings, wherein:

FIG. 1 is an elevational view of a drilling bit constructed in accordance with the teachings of the invention with a portion of the cutting element in place;

FIG. 2 is a bottom view of the drill bit shown in FIG. 1;

FIG. 3 is a sectional view taken along section 3-3 of FIG. 2; and

FIG. 4 is a fragmentary view of a drilling face of the bit of FIG. 1 illustrating the stepped relationship of the matrix sections.

In FIG. 1 there is shown a drill bit constructed in accordance with the present invention that is designed for drilling hard earth formations such as chert. The bit includes a substantially truncated-conical body member 1 formed of suitable material for withstanding drilling strain. At the upper end of the body member there is formed an exteriorly threaded section 3 for attachment of the bit to a drill pipe (not shown).

The lower end of the bit is provided with a shoulder 6. Extending downwardly from the shoulder 6 is a drilling face that extends upwardly and inwardly toward the longitudinal axis of the drill bit. Affixed to the lower portion 4 of the bit is a matrix for cutting elements 8. Only two of the cutting elements are designated by the reference numeral 8, although a multiplicity of the cutting elements are shown. The cutting elements may be diamonds, tungsten carbide chips, and the like. The matrix is formed and suitably aifixed to the bit in the usual manner.

An axial bore 18 is formed in the threaded neck 3. Extending downwardly from the bore are a plurality of ports 17 for the purpose of conducting drilling fluid to the bottom of the bit. The ports 17 open at the bottom of the bit and are positioned so that the drilling fluid will jet against the central core formed by the drill bit so as to erode the core. arranged around the longitudinal axis of the drill bit.

Extending outwardly from the lower opening of ports 17 are a plurality of rather wide water courses 13. The dimensions of the water courses may be between $4 inch wide by 4 inch deep up to V2 inch wide by inch deep, depending upon the size of the bit. While the water courses are shown as extending radially outwardly from the ports 17, it is to be understood that the water courses may be otherwise disposed on the drilling face of the matrix material. Other narrower water courses are also formed in the matrix. Water courses such as the one designated by reference numeral 15 extend radially outwardly from the center of the drilling bit, whereas the water courses such as the one designated by reference numeral 16 intersect water courses 13 and 15.

Water courses 13 divide the matrix into an even number of substantially equal sections. While only four sections are shown in the drawing, it is to be understood that a greater number may be utilized. First alternate sections 9 are at different level from second alternate sections 7 so that, initially, the first alternate sections 9 are bearing against the formation to be drilled. The second alternate sections are slightly recessed from theearth formations to be drilled. The diiference D (see FIG. 4) between the levels of the first and second alternate sections is substantially the drilling length of the cutting elements 8 embedded in the matrix. This distance will be between inch and A inch. While the drilling elements are shown as projecting normal to the surface of the matrix, it is to be understood that the cutting edges may be angularly disposed to the matrix, as is shown in U.S. Patent No. 2,371,490.

The stepped relationship of the matrix sections may be obtained by making the matrix of various thicknesses or by forming the bit in a stepped manner and having the matrix of the same thickness, or by a combination of the two types of construction.

The cutting elements 13 may be formed in rows extending substantially radially outwardly from. the longitudinal axis of the bit.

When the bit is in operation the diamonds held by the matrix sections 9 will be the first to contact the earth formations. Drilling fluid circulated through the bore 18 and through the ports 17 will flow not only through the water courses in the raised matrix sections 9, but also over the entire surface of the recessed matrix sections 7 so as to more efficiently cool the bit during drilling. As the bit drills through the earth formations, the diamonds or other cutting elements in the raised sections 9 gradually will be worn away. Likewise, the matrix will erode as the drilling progresses. However, it will be found that due to the increased cooling efiiciency provided by the recessed sections 7, the reduced amount of water that will flow through the water courses in the raised quadrant 9 will lower the eroding action of the drilling fluid on the matrix. Furthermore, the circulation rate can be substantially increased, which will substantially increase the drilling rate. The efliciency of the bit will not be impaired because the temperature of the bit will be kept down as a result of the increased cooling eificiency thereof. In due course the diamonds held by the raised sections of the matrix will be worn away, and the diamonds in the recessed sections will more eflfectively contact the earth formations so that drilling may continue. During the second phase of the drilling opera- Patented Aug. 29, 1961 The ports '17 may be symmetricallytion, the drilling fluid will flow through the water courses in the recessed sections 7 to provide coolant for the bit. The rate of fluid flow through the water courses will be substantially higher than through the water courses in matrix sections 9. However, the cooling action will be. substantially the same in view of the fact that the flow of fluids will be almost entirely through the water courses in matrix sections 7.

It will be found that as a result of the unique configuration of the matrixand the cutting elements in the bit described above, the drilling life of the bit is substantially increased over that of a bit not having the stepped matrix arrangement described. The amount of hole that can be drilled with a bit such as described above Will be up to 50 percent greater than the amount: of hole that can be drilled with a bit having a nonstepped matrix arrangement. The bit thus may remain on bottom for a substantially longer time and will drill a greater length of hole at a higher drilling rate than has been possible with similar prior art bits.

The invention is not necessarily to be restricted to the specific structural details or arrangement of parts herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of the invention.

What is claimed is:

1. A drill bit including: a body member adapted to be connected to a drill stem; a matrix affixed to said body member and having a drilling face; a plurality of water courses extending outwardly from near the axis of said drilling bit and dividing the matrix into an even number of sections, first alternate sections of the matrix having a first thickness and second alternate sections of the matrix having a second thickness so that the drilling faces of the first alternate sections are stepped from the drilling faces of the second alternate sections by substantially the drilling length of cutting elements to be embedded therein; and cutting elements embedded in the matrix and protruding substantially the same distance from the drilling face of the matrix, the cutting elements of a given section being of substantially uniform length; and at least one passageway through said body member in fluid communication with said water courses for supplying drilling fiuid to the water courses.

2. A drill bit including: a body member adapted to be connected to a drill stem; a matrix affixed to said body member and having a drilling face; a plurality of substantially radial water courses extending outwardly from near the axis of said drilling bit and dividing the matrix into an even number of sections, first alternate sections of the matrix having a first thickness and second alternate sections of the matrix having a second thickness so that the drilling faces of the first alternate sections are stepped from the drilling faces of the second alternate sections by between inch and inch, and cutting elements embedded in the matrix and protruding substantially the same distance from the drilling face of the matrix, the cutting elements having substantially the same drilling length as the step distance between the drilling faces of the first alternate sections and the drilling faces of the second alternate sections of the matrix;

and at least one passageway through said body member in fluid communication with said water courses for sup plying drilling fluid to the Water courses.

3. A drill bit as set forth in claim 2 wherein additional water courses are provided within matrix sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,554,446 Loy Sept. 22, 1925 2,255,435 Newton Sept. 9, 1941 2,264,617 Carpenter et al. Dec. 2, 1941 2,371,490 William Apr. 10, 1944 2,381,415 William Aug. 7, 1945

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