RU2766075C1 - Pdc drill bit with locking collet - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: invention relates to a tool for drilling wells for oil and gas. The PDC drill bit includes a steel body with protruding blades, flushing nodes located between the blades, a nipple part with a thread for attachment to the drill string, holes on the surfaces of the blades with rotating diamond cutters placed in them. On the walls of the holes for the incisors and on the walls of the carbide substrates of the incisors at the same distance from the bottom of the hole and from the thrust end of the cutter, parts of a joint annular cavity having a curved shape in cross section with end ledges on the wall of the hole and on the wall of the cutter substrate perpendicular to their axes are made. A locking collet conical spring ring is installed inside the joint annular cavity, resting with a small base on the end ledge on the carbide substrate of the cutter, and with a large base on the end ledge on the wall of the hole for the cutter. To ensure constant rotation of the PDC cutters during drilling, their cutting planes, touching the face with the cutting edges, are inclined relative to the plane passing through the center of the plate and the axis of the bit, at an acute angle, for example, within 5-15 degrees, clockwise or counterclockwise.

EFFECT: increase in the durability of PDC cutters, penetration by the drill bit, mechanical drilling speed is provided.

2 cl, 4 dwg

Description

The present invention relates to a deep well drilling tool.

The new century was characterized by the beginning of widespread use in deep drilling of coneless bits of the cutting type PDC (Polycristalline Diamond Cutter). These bits are equipped with round cutting inserts containing a single crystal of diamond, artificially grown from diamond powder, at an enormous pressure of 1 million pounds per square inch, at temperatures up to 3000 degrees Fahrenheit, in about a day. This complex technology was published by the famous General Electric Company (USA) in 1954.

Fine-grained powders of natural or artificial diamonds are used as the starting material. The only crystal grown from them has not only unique strength properties, but also high heat resistance. In this crystal, there are no intercrystalline boundaries and the composition cementing these boundaries, which are constantly present between ordinary crystals in natural and artificial diamonds. It is precisely these unique properties that are created and used in the manufacture of diamond cutters in PDC bits. Today, PDC bits equipped with such cutters are widely and successfully used all over the world when drilling deep holes in rocks from the softest to the hardest low-abrasive ones.

The above complex technology for growing individual diamond crystals provides relatively small plates with diameters from 8 to 24 mm and a thickness of 1.5 - 2.5 mm. Such plates with a flat cutting surface are welded or soldered onto carbide cylindrical bases - substrates of the same diameter as the plates. With the help of this backing, finished PDC cutters are fixed in the holes on the body of blades of steel or matrix bit bodies. Possessing unique strength properties during abrasion, diamond plates are quite brittle and do not withstand shock loads well. Therefore, it is not possible to apply to them the method of fastening carbide teeth in the cone body, traditional for cone bits, by pressing, with a multi-ton pressing force. Fastening of PDC cutters in the holes of the blades is ensured in PDC bits by soldering with gentle temperature heating (up to 650 degrees Celsius) using PSR solder on a silver base.

Known chisel PDC with diamond cutters /Diamond chisel PDC. Catalog of drill bits of OAO Volgaburmash, 2003, Samara, p. 36/ [1] adopted as an analogue in our application. The introduction of such bits made it possible to multiply the average penetration per PDC bit compared to traditional cone bits, to bring their use in deep drilling to 70% of the total volume and to obtain a very large economic effect. However, these new high-performance bits also have their weaknesses. These are the low resistance of diamond blades when meeting interlayers of hard and strong rocks in the event of shock loads, the need to consume significantly more torque when drilling, compared to roller bits, the difficulty of controlling the overheating of the cutting edge at different penetration depths per revolution. These problems continue to need to be addressed.

Another PDC bit /Drill bit with controlled load and depth of cut is known. US patent No. 6298930 cl. Е21В 10/46, 2001/ [2], which links the depth of cut with a bit per revolution with a controlled axial load on the bit. This bit is taken as the second analogue in our application. The solutions proposed in this patent were not widely used in PDC bits, since they could not provide the expected sharp increase in drilling performance.

Another PDC bit is known /Bogomolov P.M., Grinev A.M., Krylov S.M. and others. Diamond chisel with mechanical fastening of PDC cutters. RF patent No. 2536901 class. E21B 10/573, E21C 35/197, 2014/ [3], taken as the next analogue in our application. In this analogue, the increase in drilling performance is ensured by maintainability and reuse of the repaired bit. During the repair, the position of the worn or blunt part of the PDC cutter cutting edge is replaced at the factory, or directly at the drilling site, while eliminating the three-fold heating of the PDC cutters, which was inevitable during the repair, to change the position of their cutting edge. In accordance with this patent, instead of soldering, mechanical fastening is used to fasten the PDC cutters, the cutters are installed in the desired position using a pair of locking bushes inserted into each other with conical reciprocal cones made of ductile steel. After lifting the bit and preparing it for repair, the PDC cutters are easily knocked out of their sockets by a special punch from the non-working end of the cutter, the working edge turns to the desired working position and the cutter is again fixed by driving a pair of conical bushings into each other. This eliminates the harmful triple heating of the solder and the diamond plate, which is inevitable when fixing cutters by soldering.

The maintainability of PDC bits, both with and without soldering, allows these very expensive products to be used repeatedly, dramatically increasing the effect of their use in drilling.

But, progress in bit building is constantly moving forward, more and more new design solutions appear that provide new achievements in the field of deep drilling.

One of the world's leading US bit companies, Smith Beats, part of Schlumberger Corporation, published an advertising presentation for Russian drillers in Russian, one of the sections of which is entitled "The new revolution in PDC cutter durability", which reported on the creation of a rotating PDC cutter in the bits of this company - ONYX 360. The number 360 in the designation of the bit corresponds to the possibility of turning the cutting edge of the PDC cutter during drilling around its axis by 360 degrees / Drilling company "Smith Beats", Corporation "Schlumberger". Presentation in Russian. 2013. “Creation and application in various drilling areas of the “New revolution in the durability of PDC cutters” / [4]. This presentation contains little or no specific design features that allow for circular rotation of the PDC cutter while drilling, but does present a computer model of the contact loading of the rock under the cutting edge of the PDC cutter and mentions the benefits of rotating the cutter during operation, in which the entire length of the cutter is loaded. cutting edge instead of its separate section, which is involved in fixed mounting by soldering. The use of samples of ONYX 360 bits, according to the mentioned presentation, provided an increase in average penetration per bit up to 57%.

The bit with a rotary cutter ONYX 360 is accepted in our application as a prototype.

In the sketch of the prototype, the substrate of the cutter body is shown with an annular groove on the cylindrical surface, without deciphering the rest of the shape of the locking device that prevents the cutter from flying out of the socket.

The technical result of the invention is to increase the durability of PDC cutters, penetration on bit, mechanical drilling speed.

The purpose of the present invention is to provide a PDC rotary cutter drill bit and improve its reliability.

This goal is achieved by the fact that the proposed bit with a locking collet device includes a steel body with protruding blades, flushing units located in the grooves between the blades, a nipple part with a thread for attaching to the drill string, holes on the surfaces of the blades with PDC rotating diamond cutters placed in them. , for which, on the walls of the holes for the cutters and on the walls of the hard-alloy substrates of the cutters, at the same distance from the bottom of the hole and from the thrust end of the cutter, parts of a joint annular cavity are made, having a curvilinear cross-sectional shape, with end ledges on the sides on the wall of the hole and on the substrate cutter, perpendicular to their axes; inside the joint annular cavity, a locking collet conical spring ring is installed, resting with a small base against the end ledge on the carbide substrate of the cutter, and with a large base against the end ledge on the wall of the hole for the cutter; to ensure constant rotation of the PDC cutters during drilling, their cutting planes, which touch the bottom of the cutting edges, are inclined relative to the plane passing through the center of the plate plane and the axis of the bit at an acute angle, for example, within 5 to 15 degrees, clockwise or counterclockwise her.

At the same time, the dimensions of the length and depth in the section of the groove with end ledges on the cutter substrate, as well as the dimensions of the length and depth in the section of the groove with end ledges on the wall of the hole for the cutter, must provide the necessary clearances for the unhindered installation of the locking collet conical spring ring in the jointly formed annular cavity when mounting the PDC cutter in the hole on the blade and when rotating it during drilling.

Insertion of the cutter begins with mounting a locking collet spring ring into a staggered groove in the cutter backing, similar to a watch spring that expands and then contracts. In this case, the small base of the locking collet conical spring ring is first pushed onto the cylindrical surface of the hard-alloy substrate until it hides inside the groove, and the large base remains behind the cylindrical dimension of the hard-alloy substrate in the form of a protruding cone. Further, the carbide substrate with a locking collet conical spring ring pushed into its groove begins to move, with a small axial force, into the hole for the cutter on the blade. At the same time, the wall of this hole gradually compresses the conical surface of the locking collet conical spring ring protruding beyond its dimensions until its large base opens completely along the ledge inside the groove space on the hole wall and “snaps”, fixing the axial working position of the PDC cutter, leaving to him the only possibility of movement is rotation around this axis.

In order to provide a constant force for the continuous rotation of the PDC cutters during drilling by changing the direction of the friction forces arising from their contact with the bottom, the planes of the PDC cutting inserts are set obliquely relative to the plane passing through the center of the insert and the axis of the bit, at an acute angle, for example, of the order 5 to 15 degrees clockwise or counterclockwise.

The retaining collet spring ring can be made from any known spring material, for example by stamping spring steel sheet on a press.

The dimensions in length and depth in the section of the groove with end ledges on the carbide substrate of the cutter, as well as the dimensions in the section of the groove with end ledges on the wall of the hole for the cutter, are made with clearances for the unobstructed installation of the locking collet conical spring ring in the jointly formed annular cavity before mounting the cutter PDC and with its constant rotation during storms

Since the main axial force that occurs during the operation of the bit and tends to push the cutter deep into the hole on the blade of the bit is transmitted through the flat end of the carbide substrate to the bottom of the hole for the cutter, there is practically no force pushing it out of the hole, and hence the wear of the locking collet conical spring ring from abrasion during drilling is minimal. Therefore, as a lubricant and coolant in the friction zones of a rotating PDC cutter, a flushing liquid is sufficient.

The proposed version of the PDC drill bit with a locking collet device allows, when drilling, to use the entire length of the rotating diamond cutting edge of the cutter instead of its limited length in the option of fixing the cutter by soldering. Due to this, the durability of the cutter is multiplied, and a large economic effect is obtained.

LIST OF DRAWINGS

The invention is illustrated by drawings, in which FIG. 1 shows a general view of the PDC bit, FIG. 2 is a bottom view of the bit with a section A - A of the body along one of the cutters with a locking device, FIG. 3 is an enlarged longitudinal section along the section A - A of the locking collet conical spring ring, FIG. 4 - enlarged node I of the longitudinal section along the section A - A.

In FIG. 1 positions indicate: 1 - bit body, 2 - PDC cutters, destroying rock at the bottomhole, 3 - PDC cutters, protecting the bit body from loss of diameter when drilling a well, 4 - body blade, 5 - cavities to ensure bottomhole flushing from cuttings, 6 - grooves on the body for "screwing - unscrewing" the bit when it is fastened, 7 - conical thread for connecting the bit to the drill string.

In FIG. 2 the elements shown in FIG. 1 and 8 - flushing units, as well as the direction of the section A - A passing through the plane of symmetry of one of the PDC cutters.

In FIG. 3 the elements shown in FIG. 1 and FIG. 2, as well as the positions indicated: 9 - a locking collet spring conical ring with two plane - parallel bases: a small base 10 and a large base 11, a set of conical windows - slots 12 from the side of the small base 10 and another set of conical windows - slots 13 from the side larger base 11. On the conical surface of the locking collet spring conical ring 9 near the larger and smaller base, to increase contact with the surfaces of the protrusions on the wall of the hole and the cutter, thickenings indicated by positions 14 and 15 can be located.

In FIG. 4 positions are marked: the end of the cutter 21, the wall of the hole 16 with the bottom 17, on the wall of the hole 16 there is an annular groove 20 with two end ledges on the wall of the hole for the cutter 18 and 19. end ledges on the carbide substrate of the cutter 22 and 23.

SOURCES OF INFORMATION

1. PDC diamond chisel. Catalog of drill bits of OAO Volgaburmash, 2003, Samara, p. 36.

2. Drill bit with controlled load and depth of cut. US patent No. 6298930 cl. E21B 10/46, 2001

3. Bogomolov R.M., Grinev A.M., Krylov S.M. and others. Diamond chisel with mechanical fastening of PDC cutters. RF patent No. 2536901 class. E21B 10/573, E21C 35/197, 2014

4. Drilling company "Smith Beats", Corporation "Schlumberger". Presentation in Russian. 2013. “Creating and applying in various drilling areas the “New Revolution in PDC cutter durability”.

Claims (2)

1. PDC drill bit, including a steel body with protruding blades, flushing units located between the blades, a nipple part with a thread for attaching to the drill string, holes on the surfaces of the blades with rotating diamond cutters placed in them, characterized in that on the walls of the holes under the cutters and on the walls of the hard-alloy substrates of the cutters at the same distance from the bottom of the hole and from the thrust end of the cutter, parts of the joint annular cavity are made, having a curvilinear cross-sectional shape with end ledges on the wall of the hole and on the wall of the cutter substrate, perpendicular to their axes; inside the joint annular cavity, a locking collet conical spring ring is installed, resting with a small base against the end ledge on the carbide substrate of the cutter, and with a large base against the end ledge on the wall of the hole for the cutter; to ensure constant rotation of the PDC cutters during drilling, their cutting planes, relating to the bottomhole with cutting edges, are inclined relative to the plane passing through the center of the plate and the axis of the bit, at an acute angle, for example, within 5-15 degrees, clockwise or counterclockwise. 2. The PDC drill bit according to claim 1, characterized in that the dimensions in length and depth in the section of the groove with end ledges on the carbide substrate of the cutter, as well as the dimensions in the section of the groove with end ledges on the wall of the hole for the cutter, are made with gaps for unobstructed installation of a locking collet conical spring ring in a jointly formed annular cavity before mounting the PDC cutter and with its constant rotation during drilling.

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