US3318399A - Diamond bits and similar tools - Google Patents

Description

May 9, 1967 N. E. GARNER DIAMOND BITS AND SIMILAR TOOLS 3 Sheets-Sheet 1 Filed March 22, 1965 o A o A AP= 500 P51.

5 AP: I000 as.

V AP= aooo P.S.l.

3 I woznom wumou ZFZONEOI VERTlC /?L FORCE POUNDS FIG. 2

ROTATION Norman E. Garner INVENTOR- QA ATTORNEY y 9, 967 N. E. GARNER 3,318,399

DIAMOND BITS AND SIMILAR TOOLS Filed March 22, 1965 5 Sheets-Sheet 2 AP RANDOM SET d Ill g Em 3 F16 3 h! I 3 5 o E I U E l I l L I I I I l I 0 IO so vsrmcm. FORCE ouuos "95% AF 500 P.s.l.

J g 'i' E O RANDOM SET 4 U I 5 U 9 2 E SELECTIVELY MOUNTED u c I l l I I L I l l l 0 I0 20 so 40 so VERTICAL FORCE PDUNDS |5 AP uooo P.S.I.

a, U 3 Z a! EIO /IA FIG 5 u SELECTIVELY MOUNTED 1: A 8 g m RANDOM SET 0 5 A/ o l l l l I I I l l I VERTICAL FORCE POUNDS Norman E'.-Gorner I N VEN TOR.

ATTORNEY May 9, 1967 N. E. GARNER DIAMOND BITS AND SIMILAR TOOLS I5 Sheets-Sheet 5 Filed March 22, 1965 AP: 2000 am.

SELECTIVELY MOUNTED RANDOM SET 15 A 0 5 O 4 s D N u 0 P -v E m m6 L AF w T R E v 0 2 kmzum O SELECTIVELY MOUNTED STONES WATER A SELECTIVELY MOUNTED STONES MUD O RANDOM SET STONES WATER A RANDOM SET STONES MUD BIT WEIGHT POUNDS FIG. 7 Normdn E. Garner INVENTOR.

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ATTORNEY United States Patent f 3,318,399 DIAMOND BITS AND SIMILAR TOOLS Norman E. Garner, Houston, Tex., assignor to Esso Production Research Company, a corporation of Delaware Filed Mar. 22, 1965, Ser. No. 441,663 3 Claims. (Cl. 175329) The present invention relates to tools for penetrating rock and similar material and is particularly concerned with diamond drill bits, reamers, underreamers and related tools used in the petroleum and mining industries.

Diamond drill bits and similar tools are widely used for drilling boreholes in subterranean formations. The performance of such tools depends in part upon the way in which the diamonds are set in the matrix. Due to differences in the spacing of the carbon atoms in the diamond lattice, most diamonds are stronger in certain directions than in others. The direction of maximum strength is normally parallel to the diagonal of an internal cube face in the lattice. By placing each diamond so that the resultant of the forces applied to it is transmitted in this direction, the performance of a bit or similar tool can generally be improved. The required placement of a diamond is normally determined by reference to its external structure. With octahedral stones, each diamond should be positioned so that an octahedral face contacts the underlying formation at a negative rake angle of about 30. Cubic and dodecahedral diamonds must be set in somewhat diiferent positions. The placement of the stones in this manner is generally practical only where they have well defined, easily discernible faces. Where the stones are worn, fractured or composited so that the faces can not be readily identified, a study of their in ternal crystalline structures becomes necessary. The added cost of such a study tends to offset any savings that might be realized through selective placement. The diamonds on most commercial bits and similar tools are therefore set without regard for the crystalline faces. Tools containing such diamonds are often referred to as random set tools.

It is therefore an object of the present invention to provide improved diamond bits and similar tools which will penetrate subterranean formations more effectively than random set tools available in the past. Another object is to provide improved bits and similar tools on which diamonds are selectively positioned to secure better performance without substantially increasing the diamond setting costs. the invention is described in greater detail hereafter.

In accordance with the invention, it has now been found that the performance of diamond drill bits, reamers, underreamers and similar tools containing irregularly shaped diamonds lacking well defined crystalline faces can be substantially improved by orienting at least a majority of the diamonds so that the angle between the surface of each diamond immediately adjacent the drilling point and a plane passing through the apex of the drilling point parallel to the matrix is greater at the leading edge of the stone than at other points. Tests have shown that this method of setting the diamonds permits substantially higher penetration rate than can be obtained with random set tools available in the past and does not result in excessive wear of the diamonds. It does not require a detailed crystallographic study of each diamond, is not limited to the use of high quality stones having easily discernible crystalline faces, is applicable to salvaged diamonds or irregular shape, and can be carried out without substantially increasing the overall setting cost per tool. As a result, the method has much wider applicability that diamond setting methods employed in the past.

The nature and objects of the invention can best be Still other objects will become apparent as v 3,318,399 Patented May 9, 1967 understood by referring to the following detailed description and to the accompanying drawing in which:

FIGURE 1 is an enlarged sectional View of a portion of a diamond drill bit and the underlying formation showing the placement of a diamond in the matrix;

FIGURE 2 is a graph showing the relationship between the vertical force applied to a diamond and the resultant horizontal force transmitted to the underlying formation;

FIGURE 3 is a graph showing the volumes of rock removed by a diamond mounted in accordance with the invention and a diamond mounted in the conventional manner with zero pressure differential across the face of the rock formation;

FIGURE 4 is a graph showing the volumes of rock removed by the two diamonds under a fluid pressure differential of 500* lbs. per square inch;

FIGURE 5 is a graph showing the volumes of rock removed by the two diamonds under a pressure differential of 1000 lbs. per square inch;

FIGURE 6 is a graph showing the volumes of rock removed by the two diamonds under a pressure differential of 2 000 lbs. per square inch; and,

FIGURE 7 is a graph showing the difference in the drilling rate obtained with a full size bit set in accordance with the invention and that obtained with a random set bit under identical conditions.

The cross sectional view shown in FIGURE 1 of the drawing is taken along a plane extending in the direction of relative motion between the diamond and the adjacent underlying formation. The diamond 11 is embedded in a metallic matrix 12 on the lower part of the tool body and extends downwardly below the lower surface of the matrix in contact with formation 13 at point 14. The body construction and the matrix composition may be of any conventional type. The diamond shown is typical of the bortz commonly used on drill bits and similar tools employed in the petroleum and mining industries. These diamonds generally range between about 1 per carat and about 100 per carat in size, the size selected depending on the particular type of service for which the tool is intended. Diamond drill bits employed for penetrating relatively soft rock formations, such as those encountered in most oilfield drilling operations, are generally set with diamonds ranging from about 10 per carat up to about 1 per carat in size; while smaller stones between about 8 per carat and about 60 per carat are more frequently employed on bits intended for penetrating hard formations in the mining industry. As indicated in FIGURE 1, these diamonds are generally rounded stones of irregular shape and seldom have the classical cubic, octahedral or dodecadral configurations referred to in discussions of the orientation of diamonds. Since such diamonds lack easily discernible faces, a detailed study of the crystalline structure of each stone must be made by a skilled crystallographer before the stone can be oriented with respect to an internal cube face. The cost of such orientation is generally prohibitive, particularly in the case of large bits on which many small diamonds are employed.

The point 14 on the diamond shown in FIGURE 1 of the drawing is referred to as the drilling point. This point, normally selected by the diamond setter by visually examining the stone, is a relatively sharp corner or apex with an included angle that is generally greater than It may or may not correspond to a cubic or rectangular pyramidal point on a cubic, octahedral or dodecahedral diamond. Diamonds of the type shown are seldom symmetrical and hence the longitudinal axis of such a stone is normally taken as the straight line interconnecting the drilling point and the most remote opposed point on the diamond surface. On most random set tools, the longitudinal axis of each diamond will extend at approximately right angles to the surface of the matrix in which the diamond is embedded. The diamond surfaces adjacent the drilling point may extend upwardly at various angles with respectto the longitudinal axis. On each stone, there will normally be one surface which extends upwardly from the drilling point ata greater angle than do the others. On random set tools, differences in diamond configuration adjacent the drilling point are nottaken into consideration.

The present invention is based on the discovery that the performance of diamond bits and similar tools can be improved significantly by selectively mounting the individual stones withoutjregard for their crystallinefaces :and'internal structure. The setting of at least a majority of the diamonds, preferably all of them, so that the angle between the diamond and underlying formation at the point of contact is greater at the leading edge than at the trailing edgeperrnits substantially higher drilling rates than can normally be obtained with random set tools I and yet avoids the high costs associated with conventional diamond orientation methods proposed in the past.

This type of mounting, illustrated in FIGURE 1 of the drawing-requires that the angle facing in the direction of relative motion of the diamond with respect to the underlyingformation be greater than the angle facing away from the direction of relative motion.- Angle a in'FIGURE 1 is thus greater than angle ,8. Each. diamond is preferably rotated about its longitudinal axis todetermine the surface which extends upwardly from the drilling point at the greatest angle with respect to a plane through the drilling point at right angles to the longitudinalaxis. The stone is then mounted so that this surface will face in the direction in which the diamond is to move relative to the underlying formation. On a drill bit or similar tool where the motion takes place about a fixed .axis, the stone should be mounted so that the selected surface faces a't right angles to a radius through the fixed axis. On tools designed 'for rectilinear motion, the surface selected should face in the direction of motion. In either case, the setting of the diamonds as described increases the horizontal force which can be applied to the formation by moving the diamond in contact with the formation under a given vertical load. The horizontal forcev component is directly related to the I .ene'rgytransmitted to the rock at constant diamond pene-,

trationkand hence an increased drilling rate, is obtained.

' surface adjacent the drilling point and then gluing it in a shallow depression in inner wall of a refractory moldv with this surface facing in the direction of relative mo- .tion of'the diamond with respect to the formation, most diamonds can be set rapidly. The crystalline structure of'the diamond does not haveto be considered and hence particular faces need not be identified with respect to the crystallat-tice. Once the diamonds have been glued in place or otherwise mounted in the mold, the

supporting matrix can be formed by the liquid phase sintering of a suitable metallic powder or mixture of This member was then placed in the high pressure chamher above a rock sample mounted in a rotatable sample holder. Strain gauges mounted on the memberand associated parts were connected to a recording device for measuring the forces transmitted to the rock as it moved beneath the diamond. The rock employed was an Indiana limestone. In each test the diamond was forced into the rock under various vertical loads and the horizontal force was then measured as the rock was rotated. The volume of the groove formed was also measured. Tests were carried out at differential pressures across the face of the formation up to 2000 lbs. per square inch. The

' results of these tests are shown in FIGURES 2 through 6 of the drawing.

FIGURE 2 shows the results of tests carried out with the diamond in two different positions. In the first series of. tests, the diamond was positioned so that the angle between the diamond surface and the rock sample at the point of contact was greater at the leading edge than at the trailing edge. Curve A in FIGURE 2 depicts the results. In the second series, the diamond was displaced 180 from the earlier position. The results of these later tests are shown by curve B. It will be noted that the data points give two well-defined curves when the measured horizontal force is plotted against the applied vertical force; For a given vertical force, the horizontal forces were much greater with the diamond mounted so that the angle at the leading edge exceeds that at the trailing edge. This was true regardless of the differential pressure across the face of the rock sample. Since the measured horizontal force is directly proportional to the amount of energy transmitted to the rock, it is apparent that the diamonds positioned in accordance with the invention were considerably more eifective than those positioned so that the angle at the trailing edge exceeded that at the leading edge.

The results shown in FIGURE 2 of the drawing are confirmed by the data set forth in FIGURES 3 through 6. The latter figures show groove volume as a function for, (1) diamonds which were mounted so that the angle at the leading edge exceeded that at the trailing edge and powders. Conventional infiltration or'high pressure sintering techniques, may be used.

The advantages of setting the diamonds on a bit or similar tool in the manner described above can be seen by considering the results of tests carried out in a high pressure chamber provided with means fornneasuring- (2) random set diamonds. It. can be seen from the curves that the groove volume per inch of travel was sig nificantly greater for the diamonds positioned in accordance with the invention than for the random set diamonds. In each case the positioning of the diamonds so that the angle between the diamond surface and the underlying formation at the point ofcontact was greater at the leading edge than at the trailing edge permitted the removal or more rock than could be removed with the random oriented stones. The differential pressures across the face of the formation had only a slight effect on the volume of rock removed.

FIGURE 7 is in the drawing depicts the results obtained with two 5 inch diamond bits in drilling through Indiana limestone. Two series of tests were carried out, one using water as the drilling fluid and the other employing a conventional bent-unite mud. A rotary speed of revolutions per minute and a fluid circulation rate of gallon per minute were employed in all of the tests. ,The two bits used were identical except for the setting of the diamonds. In one case the diamonds were random set in the usual manner. In the other case, each diamond was positioned so that the angle between the diamond surface and the underlying formation at point of contact was greater at the leading edge than at the trailing edge. Each bit was tested at three different weights. The penetration rate was determined by measuring the time required to drill a fixed distance in the limestone. As can be seen from the drawing, the bit on which the diamonds were set in accordance with the invention consistently outperformed the random set tool. The drilling rate was about to percent higher for the bit of the invention. These results show that the setting of at least a majority of the diamonds on bits and similar tools so that the angle at the leading edge of each stone exceeds that at the trailing edge has pronounced advantages,

Although the invention has been described above in terms of diamond drill bits, it will be understood that the improvement shown is not limited to such tools. The setting of the diamonds on core bits, reamers, underreamers and similar tools employing diamonds to penetrate subterranean formation-s so that the angle at the leading edge of at least a majority of the diamonds is greater than that at the trailing edge is advantageous.

What is claimed is:

1. A tool for penetrating rock and similar materials which comprises:

(a) a tool body composed at least in part of a metallic matrix; and,

(b) a plurality of rounded diamonds of irregular shape embedded in the surface of said matrix and protruding therefrom, said diamonds including drilling points extending beyond the matrix surface for engaging the material to be penetrated and at least a majority of said diamonds being oriented so that the angle between the diamond surface at the leading edge of each stone and a plane passing through the apex of the drilling point parallel to the matrix surface is greater than the angle between the diamond surface and said plane at the trailing edge of said stone.

2. A diamond bit for drilling boreholes in the earth which comprises:

(a) a bit body including a metallic matrix at the lower end thereof; and, er end thereof; and

(b) a plurality of rounded diamonds of irregular shape embedded in the lower surface of said matrix and protruding therefrom, said diamonds including drilling points extending beyond the matrix surface for engaging the underlying formation and at least a majority of said diamonds being oriented so that the most nearly vertical surfaces on said diamonds immediately adjacent the drilling points face in the direction of bit rotation.

3. A diam-0nd bit for drilling boreholes in the earth which comprises:

(a) a tubular bit body provided with a metallic matrix at the lower end thereof; and

('b) a plurality of diamonds embedded in the lower surface of said matrix, the crystalline axes of said diamonds being random oriented, each of said diamonds including a drilling point projecting downwardly below the lower surface of the matrix for engaging the underlying formation, and at least a majority of said diamonds being oriented so that the angle between the diamond surface immediately adjacent the drilling point and a plane passing through the apex of the drilling point parallel to the surface of the matrix surrounding each diamond is greater in the direction of relative motion of said diamond with respect to said underlying formation than at other points about the diamonds periphery.

References Cited by the Examiner UNITED STATES PATENTS Re. 23,632 3/1953 Zublin 329 2,371,488 3/1945 Williams 175330 3,027,952 4/1962 Brooks 175329 3,058,535 10/1962 Williams 175-330 CHARLES E. OCONNELL, Primary Exdmin'er.

R. E. FAVREAU, Assistant Examiner.

Claims (1)

1. A TOOL FOR PENETRATING ROCK AND SIMILAR MATERIALS WHICH COMPRISES: (A) A TOOL BODY COMPOSED AT LEAST IN PART OF A METALLIC MATRIX; AND, (B) A PLURALITY OF ROUNDED DIAMONDS OF IRREGULAR SHAPE EMBEDDED IN THE SURFACE OF SAID MATRIX AND PROTRUDING THEREFROM, SAID DIAMONDS INCLUDING DRILLING POINTS EXTENDING BEYOND THE MATRIX SURFACE FOR ENGAGING THE MATERIAL TO BE PENETRATED AND AT LEAST A MAJORITY OF SAID DIAMONDS BEING ORIENTED SO THAT

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