RU2766858C1 - Pdc drill bit with rotating cutters - Google Patents

Abstract

FIELD: mining industry.SUBSTANCE: invention relates to a tool for drilling wells for oil and gas. The PDC drill bit with rotating cutters includes a steel body with protruding blades, flushing nodes located in the grooves 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 cutters and on the walls of the carbide substrates of the cutters at the same distance from the bottom of the hole and from the end of the cutter, a joint annular cavity is made, having a circular shape in cross-section, which is connected to the outer surface of the blade by a circular hole with a diameter of at least the diameter of the cross-section of the annular cavity, into which a locking steel rod of circular cross-section, pointed at one end and flat at the other, is installed. The length of the locking rod inside the circumference of the annular cavity from the pointed part to the end is limited by the central angle a = 290-300 degrees. The planes of the plates of the PDC cutters, 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 ranging from 5 to 15 degrees clockwise or counterclockwise.EFFECT: invention provides an increase in the durability of PDC cutters, an increase in penetration per bit and mechanical drilling speed.3 cl, 5 dwg

Description

The present invention relates to a tool for drilling wells for oil and gas.

The 2000s are characterized by the beginning of widespread use in deep drilling both in our country and abroad of coneless bits of the PDC (Polycristalline Diamond Cutter) cutting type. These bits are equipped with a new type of round diamond cutting inserts. They consist of a single crystal of diamond, artificially grown from diamond powder, under truly extreme conditions - a pressure of 1 million pounds per square inch, created on a six-position press, at temperatures up to 3000 degrees Fahrenheit, over a period of about a day. This super complex technology was created by the General Electric Company (USA) for more than 50 years and became known in 1954.

Fine-grained diamond powders are used as the starting material. A single crystal grown from them has many times higher strength properties and heat resistance. This is due to the absence of intercrystalline boundaries in a single crystal and the composition cementing these boundaries, which are constantly present in natural and artificial diamonds. These unique properties of the crystals are used to make diamond cutters in PDC bits. Today, PDC bits equipped with such cutters are widely and successfully used in drilling deep wells in rocks from the softest to hard, low-abrasive.

The above technology for growing individual diamond crystals provides relatively small plates with diameters from 8 to 24 mm. and 1.5-2.5 mm thick. 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 substrate, 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, the method of fastening carbide teeth into the holes of cone bits, traditional for cone bits, is not applied to them, the method of pressing with a large pressing force. Fastening of PDC cutters in the holes of the blades is ensured by soldering with gentle temperature heating (up to 650 degrees Celsius) with silver-based PSR solder.

Known bit PDC with diamond cutters /Diamond bit. FD line. Catalog of drill bits of OAO Volgaburmash, 2003. C 34-37/ [1], adopted as an analogue in our application. The introduction of such bits made it possible to increase the average penetration per bit up to ten times compared to traditional cone bits and bring their use in deep drilling to 70% of its volume and obtain a very large economic effect. However, these high-performance bits also have their weaknesses. These are the low resistance of diamond blades when meeting interlayers of hard and strong rocks, the need to consume many times 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 depth of cut and load is known. US patent No. 6298930, class. E21B 10/ 46. 2001./ [2], which links the depth of cut with a bit per revolution with a controlled axial load on the bit, 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 a sharp increase in drilling performance.

Another PDC bit is known /Bogomolov P.M., Grinev A.M., Krylov S.M. etc. "Diamond chisel with mechanical fastening of cutters", patent of the Russian Federation No. 2536901 class. E21B 10/573, F21C 35/197. 2014/. [3], taken as the next analogue in our application. In this analog, the increase in drilling performance is ensured by the maintainability and reuse of the repaired bit after replacing the position of the worn or dull part of the cutting edge of the PDC cutter directly in drilling conditions, while eliminating the previously inevitable three-fold heating of the PDC cutters when replacing the position of their cutting edge. In accordance with this patent, instead of soldering, the PDC cutters are fixed by mechanical fastening of the set cutters 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 position and the cutter is again fixed by driving a pair of conical bushings. 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 manufacturers, Smith Beats, part of the Schlumberger Corporation, published an advertising presentation for Russian drillers in Russian, one of the sections of which is entitled "The New PDC Tool Life Revolution", announcing the creation of rotary cutter PDC 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 the axis by 360 degrees /Creation and use in various drilling areas of rotating cutters. "A 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. The use of samples of ONYX 360 bits provided an increase in average penetration by 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 and mechanical drilling speed.

The objective of the present invention is to create a drill bit with rotating cutters and improve the reliability of its operation.

This task is achieved by the fact that the proposed bit 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 placed in them by rotating PDC diamond cutters for which on the walls of the holes under the incisors and on the walls of the incisor substrates, at the same distance from the bottom of the hole and from the end of the cutter, a joint annular cavity is made, having a circular cross section, which is connected to the outer surface of the blade by a round hole with a diameter not less than the diameter of the section of the annular cavity, in which the movement landing, a locking steel rod of circular cross section, pointed at one end and flat at the other, the length of the locking rod inside the circumference of the annular cavity from the pointed part to the end is limited by the central angle α=290-300 degrees, while the planes of the PDC cutter inserts touching the bottom with the cutting edges ami, inclined relative to the plane passing through the center of the plate and the axis of the bit at an acute angle, ranging from 5 to 15 degrees, clockwise or counterclockwise. To prevent cuttings from entering the contact zone of the rotating cutter with the locking rod or the wall of the annular cavity, the round inlet hole after installing the locking rod must be closed by any known method, for example, using a plug and welding.

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 with one of the cutters with a locking device, FIG. 3 - an enlarged assembly with a longitudinal section A-A and a cross-section of the cutter B-B along the locking rod, FIG. 4 is a diagram of the location and mounting of the locking device, FIG. 5 is a diagram of a variant of installing the inlet cover for the locking rod.

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, as well as positions indicate: 8 flushing units, 9 - covers of mounting holes for installing locking devices for PDC cutters, as well as the direction of the section A-A passing through the symmetry plane of one of the PDC cutters.

In FIG. 3 the elements shown in FIG. 1 and FIG. 2, as well as the following positions are indicated: 10 - annular locking rod, 11 - annular half-groove on the wall of the hole 13 for installing the PDC cutter, 12 - annular half-groove on the wall of the hard-alloy substrate of the cutter 2; 13 - wall of the hole for the installation of the cutter 2 in the blade 4; 14 - the bottom of the hole for installing the cutter 2.

In FIG. 4, the same positions indicate the elements shown in the previous figures 1-3, and also the positions indicate: 15 - mandrel for mounting the annular locking rod 10, 16 - hole for inserting the mandrel 15; 17 - cover for hole 16. 18 - welding fastening option for cover 17.

In FIG. 5, the same positions indicate the elements shown in the previous figures 1-4, as well as the positions indicated: 19 - pointed lead-in end of the locking rod, having a smooth anti-seize shape; 20 - the opposite flat end, providing the maximum stop area of the mandrel when installing the annular locking rod 10 in the annular channel.

To eliminate obstacles to the constant rotation of the PDC cutter during drilling and reduce friction when the assembly elements come into contact with each other, the following conditions must be met. As a material for the manufacture of the locking rod, it is necessary to use ductile steel with a minimum carbon content. Such a plastic material facilitates the entry of the rod into the toroidal space formed by annular half-grooves: an annular half-groove on the wall of the hole 11 and an annular half-groove on the wall of the carbide substrate of the cutter 12, and also ensures that it remains permanently in the form of a curved part of the circle, the contact of which is possible only with the surfaces of the half-grooves 11 and 12, for this, the stopper rod must have a length limited by a central angle within 290-300 degrees, a shape pointed at the input end and flat at the other end, its size in diameter must provide a clearance for landing movement when mounted in the input hole and when location inside the annular toroidal space during rotation of the PDC cutter; this gap can be filled with anti-friction grease; to ensure forced rotation of the cutters around their axes during drilling, the cutting planes of the PDC cutter inserts that touch the bottom should be inclined relative to the plane passing through the center of the insert and the bit axis at an acute angle, within the recommended range of 5 to 15 degrees clockwise or against her. The friction forces arising from the slipping of the edges of the cutters along the bottom are guaranteed to provide the necessary moment of rotation of the cutters relative to their axes and cutting the rock at the bottom consistently throughout the entire length of the cutting edge of the diamond plate. To protect the cavity of the locking device from the ingress of sludge, any known embodiment of the cover for the inlet and its fastening can be used, for example, as shown in Fig. five.

The installation of the annular locking rod 10 in the annular toroidal channel formed by the half-spaces of the annular half-groove on the wall of the hole 11 and the annular half-groove on the wall of the carbide substrate of the cutter 12 is carried out as follows. As a starting material for the manufacture of the annular locking rod 10, mild steel is selected, for example, Art. 10. Depending on the dimensions of the cutter, for which the annular locking rod is designed and manufactured, its dimensions are assigned, as well as the necessary dimensions for making half-grooves and inlets for mounting the annular locking rod 10. Its lead end must have a smooth anti-seize shape, and the opposite end - a flat shape that provides maximum support to the end of the mandrel 15 during the installation of the locking rod. Plastic steel material facilitates the possibility of bending the rod by the surface of the toroidal groove during installation, as well as the constancy of maintaining the curved round shape obtained by bending it during the entire time of the cutter.

To reduce the braking effect of friction of the outer surface of the substrate of the cutter and the locking rod on the inner surface of the torus-shaped channel, it is planned to create landing gaps that provide, for example, a landing movement. The machined rectilinear rod is inserted into the hole 16 and with the help of a mandrel 15, calibrated along the length, it is hit by blows to the position limited by the length of the mandrel, shown in Fig. 4. In this case, the entire volume of the rod is completely inside the annular toroidal space and becomes a stopper that prevents the axial movement of the cutter and does not prevent its rotation relative to the axis, even with a minimum moment of rotation created when the cutter edge slips along the face surface. The lubricant can be introduced into the toroidal space by any known method, for example, applied to the surface of the rod, using a grease gun, or not introduced at all. The entrance to the hole 16, as noted above, can be closed by any known method, such as welding.

The present invention can significantly improve the performance of PDC diamond bits.

SOURCES OF INFORMATION

1. "Diamond chisel", "Line FD". Catalog of drill bits of OAO Volgaburmash, 2003. P 34-37.

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

3. Bogomolov R.M., Grinev A.M., Krylov S.M. etc. "Diamond chisel with mechanical fastening of cutters", patent of the Russian Federation No. 2536901 class. E21B 10/573, F21C 35/197.2014.

4. Creation and application in various areas of drilling of rotating cutters. "A new revolution in PDC cutter durability".

Claims (3)

1. PDC drill bit with rotating cutters, including 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 rotating diamond cutters placed in them, characterized in that that 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 end of the cutter, a joint annular cavity is made, having a circular cross section, which is connected to the outer surface of the blade by a round hole with a diameter not less than the diameter of the section of the annular cavity, in which is installed on the landing of the movement of the locking steel rod of circular cross section, pointed at one end and flat at the other, the length of the locking rod inside the circumference of the annular cavity from the pointed part to the end is limited by the central angle α=290-300 degrees, while the planes of the PDC cutter plates touching behind 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 ranging from 5 to 15 degrees clockwise or counterclockwise. 2. PDC drill bit with rotary cutters according to claim 1, characterized in that the round hole after the installation of the locking rod is hermetically sealed with a plug. 3. PDC drill bit with rotating cutters according to claim 1 and 2, characterized in that the annular cavity for installing the locking steel rod is filled with anti-friction lubricant.

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