EP0182770A1 - Diamond drill bit - Google Patents

Abstract

The performance of a drill bit (1) is improved by dividing the cutting elements (8) into small groups, each fixed to separate islets (4) distributed over the entire surface of the tool. In this type of tool, each rinsing orifice is advantageously equipped with an injection nozzle (7). <IMAGE>

Description

The present invention relates to a diamond drilling tool, furnished with possibly synthetic cutting elements, arranged projecting with respect to drainage zones formed by surface portions delimiting the body of the tool itself and provided with at least one washing orifice supplied with drilling fluid.

The elements considered are round natural diamonds, cubic natural diamonds, synthetic diamonds set, whether they are mono- or polycrystalline and whatever their shape or of polycrystalline diamond plates added.

The diamond drilling tools according to the present invention find their main application in the drilling of tender or semi-hard soils possibly sticky, such as clays and porous sandstones. They are also used in terrains made up of alternating layers of very soft and semi-hard terrains. Such land requires very studied hydraulics to avoid on the one hand, the regrinding of cutting waste and on the other hand, clogging of the tool.

Belgian patent No. 771,628 discloses a rotary drill bit filled with crimped stones. These diamonds are arranged on the surface of the tool in substantially radial rows and are set in the part of the tool body made up of protuberances. projecting a few millimeters high, separated by radial grooves which ensure the drainage of cutting debris by the coolant. The arrangement of crimped protrusions and recesses reserved for the drainage of the diamond coolant and the evacuation of rock debris are optimal. The drilling fluid is supplied by a wide channel in the central zone of the tool; this channel is not specially profiled and the drilling fluid terminating on the surface of the tool comes into contact with the rock with a low speed and flows preferentially according to the more or less radial water passages, the fall of overall tool pressure is generally low around ten bars.

These conventional set stone tools allow, depending on the quantity and size of the stones, to drill fairly hard to very hard terrain. On the other hand, in the soft and agglutinative grounds, they realize only mediocre performances and clog up quickly.

On the other hand, is also known by US Patent ^No. 4,323,130, diamond inserts drilling tools distributed over the surface of the tool.

These tools are widely used in two preferred forms: infiltrated carbide tools and steel tools. The two forms of tools are distinguished mainly by the chronological order of the various stages of preparation.

In general, diamond plates consist of a layer of polycrystalline diamond added to a tungsten carbide substrate by sintering.

In tools made of infiltrated carbide, the diamond plates are not fixed on the tool until the end of the operation, after molding the tool. They are joined by brazing on tungsten carbide supports previously enclosed in the body of the tool during its manufacture by infiltration.

On the other hand, in steel tools, the diamond plates are brazed on a carbide support before they are fixed to the body of the tool most often by shrinking.

The distribution of inserts meets very specific criteria of radial density as a function of the distance to the center of the tool and the angular distribution ensuring good mechanical balancing of the drilling tool. With this distribution of inserts is associated an optimal distribution of the drilling fluid supply which, in this case, consists of several conduits formed in the mass and ending at the surface of the tool in well determined locations, generally of on either side of the axis of rotation at different distances from the aforementioned axis these conduits are generally provided with injection nozzles at their end, allowing them to create powerful jets capable of avoiding clogging and possibly to contribute to the destruction of the rock.

The injection nozzles are made in one material with high wear resistance, generally sintered tungsten carbide. The drilling fluid present in the internal cavity of the tool and coming from the drill string, crossing the nozzle, is subjected to a sudden acceleration with a high hydraulic efficiency, the pressure difference between the upstream and the downstream of the jet nozzle can reach 50 to 100 bars, which corresponds to linear speeds at the orifice of the order of magnitude of 100 meters per second.

Whatever its external shape, the body of the tools described in the aforementioned US Patent No. 4,325,130 can be made either of steel or of infiltrated carbide.

This last type of tool achieves excellent performance in soft terrain and, in particular, in very soft and agglutinative terrain. However, it can be seen that the speed of penetration decreases very quickly when tackling higher hardness terrains, such as medium hardness terrains such as limestone and dolomite. There is also an increasing risk of clogging as the diameter of the tool increases and this, due to the increasing difficulty of removing cutting debris.

The present invention aims to remedy the above drawbacks. It relates to a diamond drill bit, furnished with possibly synthetic cutting elements, arranged projecting with respect to drainage zones formed by surface portions delimiting the body of the tool itself, and provided with minus one washing orifice supplied with drilling fluid, essentially characterized in that the cutting elements are grouped on islands distributed over the entire surface of the tool and separated from each other by the aforementioned drainage zones, the islands as well as the drainage zones being able to be provided with conduits fitted at their end with an injection nozzle.

In terrain with higher hardness, natural or synthetic stones are advantageously used, set on islands projecting from 1 to 10 mm in relation to the body of the tool itself.

According to a feature of the invention, the stones are arranged in isolated islands having a cutting width of 10 to 20 mm and the base set with the cutting elements is preferably protruding about 7 mm from the level of the body surface or the actual tool.

In a particular embodiment, the clogging of large diameter tools is avoided, by placing the polycrystalline diamond plates on islands projecting from 1 to 40 mm relative to the body of the tool itself.

According to a feature of the invention, the polycrystalline diamond plates are arranged in insulated islands having a cutting width of 20 to 60 mm and the base set with the support studs projects about 15 mm from the level of the surface of the tool body itself.

Other features and details of the invention will appear during the following detailed description of a preferred embodiment of the drilling tool according to the invention with cutting elements and distributed jets.

• - la figure 1 montre en perspective, un outil de forage plat à pierres serties disposées en saillie sur des protubérances réparties suivant l'invention, sur toute la surface de l'outil ;
• - les figures 2 et 3 sont des vues de bout et de plan de l'outil de forage montré à la figure 1 ;
• - les figures 4 et 5 sont des vues de bout et de plan de l'outil du type d'îlot montré aux figures 1 et 2 ;
• - les figures 6 à 11 montrent en détail trois formes de réalisation différentes de sertissage de pierre cubique susceptible d'être appliquée sur un îlot, vues respectivement en élévation latérale et en bout ;
• - les figures 12 à 17 illustrent en détail trois formes de réalisation différentes de sertissage d'une pierre prismatique susceptible d'être appliqué sur un îlot, vues respectivement en élévation latérale et en bout ;
• - la figure 18 montre en perspective, un outil de forage plat à plaquettes diamantées polycristallines disposées en saillie sur des protubérances ;
• - les figures 19 et 20 sont des vues de bout et de plan de l'outil de forage montré à la figure 16 ;
• - les figures 21 et 22 illustrent en détail une protubérance garnie de plaquettes polycristallines,
• - la figure 23 montre une forme de répartition radiale des îlots et de leurs éléments de coupe ; la figure 24 illustre la réalisation d'un îlot de grande dimension, comportant un élément secondaire de protection de plaquettes diamantées constitué d'une surface-frein, et
• - la figure 25 est une coupe d'un îlot, tel que montré à la figure 24, normale à la surface de l'outil et parallèle à la direction de coupe.

In these drawings:

• - Figure 1 shows in perspective, a flat drilling tool with crimped stones projecting from protuberances distributed according to the invention, over the entire surface of the tool;
• - Figures 2 and 3 are end and plan views of the drilling tool shown in Figure 1;
• - Figures 4 and 5 are end and plan views of the island type tool shown in Figures 1 and 2;
• - Figures 6 to 11 show in detail three different embodiments of setting cubic stone capable of being applied to an island, viewed respectively in side elevation and at the end;
• - Figures 12 to 17 illustrate in detail three different embodiments of setting a prismatic stone capable of being applied to an island, seen respectively in side elevation and at the end;
• - Figure 18 shows in perspective, a flat drilling tool with diamond inserts polycrystalline projecting from protuberances;
• - Figures 19 and 20 are end and plan views of the drilling tool shown in Figure 16;
• FIGS. 21 and 22 illustrate in detail a protuberance furnished with polycrystalline plates,
• - Figure 23 shows a form of radial distribution of the islands and their cutting elements; FIG. 24 illustrates the production of a large island, comprising a secondary element for protecting diamond-tipped plates consisting of a brake surface, and
• - Figure 25 is a section of an island, as shown in Figure 24, normal to the surface of the tool and parallel to the cutting direction.

In these figures, the same reference notations designate identical or analogous elements.

Many recent publications show the importance of hydraulics in the behavior of drilling tools to justify their performance. They study in particular the "jet effect" and the relief of tools equipped with these jets. The most common cutting elements are PDC type diamond inserts, ie "polycrystalline diamand compact".

In particular, the summary work entitled "Advanced Drilling Techniques" by William C. Maurer, with 698 pages and published in 1980 by The Petroleum Company describes various aspects of jet effects in oil drilling.

Dave Glowka's article "Optimization of Bit Hydraulic Configuration", from Sandia National Laboratories published in the technical journal "Society of Petroleum Engineers Journal" of February 1983, analyzes the behavior of tools with PDC inserts provided with washing holes not provided injection nozzles.

In fact, there are already jet tools, such as those described in US Pat. No. 4,323,130, the cutting elements are however fixed at the level of the flat bottom surface of the tool die.

• - un profil quelconque muni éventuellement d'un évidement conique 2 ;
• - une distribution des éléments de coupe 3 sur toute la surface de l'outil, non pas répartis suivant des "lames" ou "ailes", ni non plus complètement isolés les uns des autres, mais plutôt groupés en surélévation sur des îlots 4, séparés entre eux par des zones de drainage 5 dans le but de favoriser leur refroidissement et l'élimination de débris de roches ;
• - une alimentation en fluide de forage au travers de conduits 6 aboutissant à la surface de l'outil, soit dans les zones de drainage 5, soit dans les îlots 4, dirigés vers la formation et en général garnis chacun à leur extrémité d'un "jet nozzle" 7, c'est-à-dire d'un ajutage constitué d'un matériau offrant une résistance particulière à l'érosion et qui, par son profil bien étudié, permet la mise en vitesse du fluide de forage avec un bon rendement hydraulique. Les canaux peuvent aboutir dans les canaux de rinçage ou encore dans les îlots.

These jet tools according to the invention, designated as a whole by the reference notation 1, differ from other drilling tools by the set of the following elements:

• - any profile possibly provided with a conical recess 2;
• a distribution of the cutting elements 3 over the entire surface of the tool, not distributed along "blades" or "wings", nor is it completely isolated from one another, but rather grouped in elevation on islands 4, separated from each other by drainage zones 5 in order to promote their cooling and the removal of rock debris;
• a supply of drilling fluid through conduits 6 leading to the surface of the tool, either in the drainage zones 5 or in the islands 4, directed towards the formation and in general each furnished at their end with a "jet nozzle" 7, that is to say with a nozzle consisting of a material offering a particular resistance to erosion and which, by its well studied profile, allows the drilling fluid to speed up with good hydraulic efficiency. The channels can end up in the rinsing channels or in the islands.

The speed of the drilling fluid reaches at the outlet of the jet, preferably an order of magnitude of 100 m / s.

The strong turbulence thus obtained favors the removal of rock debris and contributes to preventing regrinding of the debris which reduces both the speed of penetration of the tool and the longevity of the tool.

They prevent clogging of the tool in very soft and sticky terrains; it is also estimated that in very soft soils, the drilling fluid entering at high speed in contact with the rock participates in the destruction of the latter provided that the nozzle is directed towards the formation.

As illustrated in FIGS. 1 to 3, in a crimped stone drilling tool, each Island 4 comprises several cubic stones 8, crimped by their base in a protuberance consisting of a surface portion 9 projecting from the surface level outside of the tool body.

In this case, the portion of the surface 9 on which are set with stones, protrudes from a height which may be at most equal to the cutting width of the island, this value being considered as a technological limit.

Three cubic stones 11 of about four millimeters, are crimped in two rows so as to ensure complete recovery by island. The projection advantageously emerges from about 7 mm from the surface of the tool body.

Two stones 11 'placed at the front ensure a sufficient cutting width, for example of the order of magnitude of the cutting width of a traditional wafer of 13.3 mm in diameter. The two front stones 11 'are followed by a third 11 "stone placed between the wake of the first two.

FIG. 3 shows that the distribution of the stones according to the present invention is inspired by that carried out for the flat tools with distributed inserts insofar as the stones are arranged in isolated islands 4 and distributed according to laws similar to those used for inserts . Each island comprises several stones so as to ensure, for each island, a sufficient cutting width which, in the case of the example described and of the order of magnitude of the cutting width of the inserts usually used on flat tools with inserts distributed. The supply of drilling fluid is identical to that described in FIG. 2 and therefore also has the same advantages.

Figures 4 and 5 describe in detail a possible embodiment of the islands comprising the elements cutting. In this case, the surface position 9 on which the cutting elements are crimped projects about 7 millimeters from the body of the tool itself 10. Three stones 8 are crimped in two rows so as to ensure overlap complete by island.

Figures 6 to 11 give three examples of positioning in the matrix of a cubic cutting element. Thus Figures 6 and 7, 8 and 9 as well as 10 and 11 are respectively end views and side elevations of the above examples, the direction of travel of the rock is indicated in the three cases by the arrow 12, Figures 6 9 show that the cubic cutting element can be positioned so as to present a flat face 13 to the rock, the element penetrating most deeply into the rock being the corner 14 in the case 6 and the edge 15 in the case 7.

Figures 10 and 11 show that the cubic cutting element can be positioned so as to present an edge 16 to the rock; in this case, the element penetrating the deepest into the rock is necessarily the corner 17.

In all three cases, the cutting element is positioned so as to have a clearance angle 18, which is generally between 5 and 30 degrees, counted positively as indicated by the figures.

FIGS. 12 to 17 are three examples of positioning in the matrix of a prismatic cutting element with a triangular base 19.

These representations are similar to those Figures 6 to 11 relating to cubic stones, they are given with the same numbering 20,21,22,23,24, 25, 26.

FIGS. 18 to 20 show a possible embodiment of islands 4 comprising polycrystalline diamond plates 27 brazed on carbide pads 28 set in the body 10 of the drilling tool 1.

The surface 9 on which the diamond plates 27 are crimped protrudes relative to the body of the tool itself by a height which may be at most equal to the cutting width of the island, this value being considered as a limit technological.

Three traditional diamond plates 27, for example 13.3 mm in diameter, are crimped onto an island 4 advantageously emerging from 15 mm from the surface of the body 10 of the tool.

The arrangement of the plates 21 on each island 4 and the distribution of the islands are chosen so as to ensure complete covering of the island.

As illustrated in FIGS. 21 and 22, two front inserts are placed for example, in order to ensure a cutting width of approximately 35 mm. The front diamond plates 21 'are followed by a third plate 21 "disposed between the wakes of the first two.

On the surface of the island can terminate a fluid inlet pipe 6 provided with a nozzle tion 7 whose axis directed towards the formation, is also inclined towards the diamond plates, as illustrated in FIGS. 15 and 16.

FIG. 23 shows a possible form of radial distribution of the cubic cutting elements 8. The elements and the islands 4 are arranged at different distances from the axis of rotation of the tool. The radial offset between two successive studs is such that the cutting element located outside an island i is coincident in projection with the cutting element located in the center on island i + 1 and also coincident in projection with the cutting element located on the right on the i + 2 island; in this case therefore, each wake is traversed three times consecutively by successive elements i, i + 1 and i + 2.

It is obviously possible to double the density of the cutting elements at will by multiplying the number of islands; especially in particularly stressed places.

As illustrated in FIGS. 24 and 25, the islands furnished with diamond plates can have, mainly in large diameter tools, a considerable extension; in this case, the islets can be separated by equally large drainage zones.

In very soft terrain for which these tools are intended in principle, the instantaneous feed rates can be very high so that the diamond blades 27, and mainly those located on the first row of each island 4 may have to tear off a volume huge of material and in any case far too important with regard to the mechanical resistance of the diamond insert itself or of its sintered tungsten carbide support. It follows that it will be necessary to protect the diamond blades from these potential temporary overloads by brake surfaces 29 located in front of the diamond blades and whose upper face 30 is at a level lower than that of the cutting edge of the diamond inserts with a value equal to the tolerated depth of cut. These brake surfaces 29, as illustrated in FIG. 18, are advantageously constituted by an elevation made of the same infiltrated carbide as the body of the tool itself and set with stones, for example synthetic polycrystalline cubes 11 already described so to increase the abrasion resistance by the formation of the surface 42 and to decrease the coefficient of friction thereon on this same formation; the brake surfaces 29 could also consist for example of parts made of tungsten carbide sintered with cobalt and comprising or not diamond or even, if it proved necessary, by one or more rows of diamond plates also located at a level lower than the main pads.

It is obvious that the invention is not limited to the embodiment described above and that numerous modifications can be made to the number of cutting elements crimped per island, to the distribution of the latter, as well as the number and arrangement of the nozzles without departing from the scope of the invention.

Claims (10)

1. Diamond drilling tool, provided with possibly synthetic cutting elements, arranged projecting with respect to drainage zones formed by surface portions delimiting the body of the tool itself and provided with at least one orifice of washing supplied with drilling fluid, characterized in that the cutting elements (8) are grouped on islands distributed over the entire surface of the tool and separated from each other by the above-mentioned drainage zones and in that each orifice The washing machine is fitted at its end with an injection nozzle (7). 2. Tool according to claim 1, characterized in that the cutting elements are possibly synthetic mono- or polycrystalline diamonds. 3. A drilling tool according to claim 1, characterized in that the cutting elements are polycrystalline diamond plates. 4. Tool according to claim 1 or 2, characterized in that the stones (8) are arranged in islands (4) having a cutting width of 10 to 50 mm (and preferably 10 to 20 mm. 5. A drilling tool according to claim 1 or 3, characterized in that the diamond plates are arranged in islands (4) having a cutting width of 20 to 200 mm (and preferably from 20 to 60 mm). 6. Tool according to any one of claims 1 to 3, characterized in that the base set with the cutting elements (8) has a projection less than or equal to the cutting width 40 mm relative to the level of the surface. of the body of the tool itself. 7. A drill bit according to any one of claims 1 to 3, characterized in that the cutting elements (8) are grouped by three, two of which face (11 ') followed by a third (11 ") element disposed between the wakes of the first two elements (11 '). 8. A drill bit according to any one of the preceding claims, characterized in that the washing orifices open into the islands carrying the cutting elements. 9. A drill bit according to any one of the preceding claims, characterized in that the washing orifices are inclined radially and tangentially with respect to the planar face of the tool. 10. A drill bit according to any one of the preceding claims, characterized in that the islands (4) comprise brake surfaces (29) intended to limit the depth of cut of the diamond inserts.

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