RU2774767C1 - Pdc drill bit with shock absorbers on its diameter - Google Patents

Abstract

FIELD: drill bits.

SUBSTANCE: invention relates to a PDC drill bit with shock absorbers on its diameter. The 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 rock cutting and calibrating surfaces of the blades with PDC cutters located in them. Between the ends of the PDC calibrating cutters with a diameter D and the bottom of the holes under them, flat dampers-shock absorbers of a mechanical type are installed, with a thickness "a" in the expanded state and a thickness "b" in the most compressed state, with the magnitude of the amplitude of the possible axial movement of the PDC calibrating cutter at maximum compression of the damper -shock absorber - "с". On the side surface of each carbide substrate of the PDC calibrating cutter, an annular groove of a semicircular cross section with a radius R1 and a cross section with a symmetry plane at a distance "L" from the end of the PDC calibrating cutter is made. On the wall of each hole for the PDC calibrating cutter, at a distance from the bottom of the hole, an annular groove of a semi-oval cross section is made with a width L3=2R1+с, a depth and lateral radius fillets along both edges of the semi-oval with the same radii R1, and its edge on the side of the top of the calibrating cutter PDC is located opposite the edge of the groove of a semicircular cross section. Both annular grooves form a joint annular cavity, into which, through a round mounting hole with a diameter of d1=2R1, outside the side surface of the blade, a floating annular steel stopper of circular cross section with a diameter of d, corresponding to the diameter d1 of the mounting hole, is pointed at one end and flat at the other.

EFFECT: improved tool life of PDC cutters, penetration per bit and ROP.

1 cl, 5 dwg

Description

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

Impact loads arising from lateral and longitudinal vibrations of the string, as well as from encounters with harder rock interlayers, significantly reduce the strength properties of diamond cutters and the performance of PDC bits. A specific effect on the strength of the rock-cutting surface and the hard-alloy substrate of rock-breaking PDC cutters is exerted by continuous transverse shock vibrations caused by the presence of gaps between the gauge surface of the bit and the borehole wall. The larger these gaps, the greater the amplitude and lateral transverse impacts. PDC rock cutting cutters perfectly perceive axial loads, but much worse perceive transverse, lateral loads. A new bit design is proposed with dampers-shock absorbers on the diameter, which traditionally protect the bit diameter from abrasive wear, as well as reduce the magnitude of transverse impacts while reducing the runout of the bit, and hence the transverse loads on the cutters of the main rock cutting rims on protruding blades.

In recent years, coneless bits of the PDC (P0LYCRISTALLINE DIAMOND CUTTER) cutting type, equipped with inserts grown from fine diamond powder when heated to 3000 degrees Fahrenheit and press pressure with a force of about 1 million pounds per square inch, have become widespread all over the world in recent years. about one day. The resulting single crystal does not have intercrystalline internal boundaries between individual diamond crystals, the presence of which sharply reduced the strength properties of conventional diamond plates in the cutters of diamond bits.

Equipped with diamond cutting inserts, PDC cutters have unique rock cutting properties that greatly improve the drilling performance of various types of PDC bits used for drilling low abrasive formations, from the softest to the hardest. The diamond cutting inserts used for the manufacture of PDC drill bits are limited in diameter (8 to 24 mm) and thickness (1.5 to 2.5 mm). Such inserts are welded or soldered on hard-alloy cylindrical bases-substrate, of the same diameter with diamond inserts, together with which the finished PDC cutters are fixed in the holes on the body of the protruding blades of the bit body.

Diamond inserts for PDC cutters, like the carbide substrate, can withstand very high compressive loads, as well as significant overheating (of the order of 1000 degrees Celsius) during drilling. However, as already noted, they perceive sudden or continuous cyclic shock lateral loads much worse. Therefore, the cutters are fixed by soldering at a temperature that is gentle on the diamond plate (no more than 650 degrees Celsius), on a silver-based PSR solder.

In recent years, both abroad and in our country, new designs of PDC bits have appeared, allowing for a further increase in their performance in drilling. Such an increase is provided by various methods and directions.

The first designs of PDC bits with diamond cutters are known [1], (“Diamond bit”, “FD Line”. Catalog of drill bits of JSC Volgaburmash, 2003, pp. 34-37.)

This design of such bits is taken as the first analogue.

However, all of these initial designs had their weaknesses. The replacement of the rolling friction of cutters along the bottom and the shock-shearing destruction of the rock under the rolling teeth of the cutters for impactless continuous cutting required many times more torque for the operation of the bit to ensure intensive destruction of the rock, which means the use of more powerful, expensive and more energy-intensive drilling rigs, which increase costs per meter of drilling. In addition, if the teeth of the cutters, when rolling over the face, have time to cool and “rest” between the cycles of penetration into the rock. PDC bit cutters operate in continuous, constant contact with the formation and overheat from abrasive cutting, which contributes to the accelerated failure of their cutting edges.

Known bit PDC [2], ("Drill bit with controlled depth of cut and load." US Patent No. 6298930. CL. 35/197. 2014). In this bit, in order to optimize the parameters of the drilling mode, an attempt was made to link the depth of cut per one revolution of the bit when working at the bottom with axial load, the number of revolutions and the contact surface of the PDC cutters.

The solutions proposed in this patent are only applicable to certain hardness-specific rocks. They have not become universal for a large number of different rocks, alternating in hardness, passed in one run by PDC bits. This bit is taken as the second analogue.

Another PDC bit is also known [3], (“Diamond bit with mechanically fastened cutters”. Bogomolov R.M., Kinyaev A.V., Krylov S.M. et al. Patent RF No. 2536901, class E21B 10/573, F21C 10 /197, 2014). An increase in the performance of the armament of this bit is achieved by providing subsequent new applications of the repaired bits. The solutions offered in this bit make it possible, after replacing the position of a small section of the cutting edge of the PDC cutter, worn or chipped after lifting the bit, directly in the conditions of the drilling rig, with the exclusion of their laborious collection and delivery for repair to the manufacturer, to avoid additional heating cycles during desoldering and new sealing when replacing or reversing the cutter, ensuring their reuse. This improves the overall total tool life of the PDC cutter and the performance of the bit as a whole. Such a bit is taken as the third analogue.

Another PDC bit is known [4], (“Drill bit with PDC cutters”. P.M. Bogomolov, RF patent No. 2735319. class E21B 10/43.2020). An increase in the performance of this bit is achieved due to the rational arrangement of the PDC cutters on the blades. The incisors alternate one after another on the crown. One part of the cutters is turned relative to the projection on the face plane of the line connecting the centers and diameters on the planes of the plates with the axis of the bit, at an acute angle ranging from 5 to 35 degrees clockwise, and the second part, within the same limits, is turned counterclockwise . This allows you to purposefully regulate the stress state, the zone and the loading diagram under the cutter pressed into the rock, create and enhance the lateral shift of the rock between the annular collars at the bottom that was previously absent during drilling.

In all four above-mentioned bit designs, options for fixed fixation of PDC cutters are provided, in which only a small part of the length of the annular cutting edge that cuts into the surface of the bottomhole (about 10-15%) is continuously in contact with the bottomhole rock, when indented in one revolution, which perceives the cutting load during the entire time of drilling with a bit, and the rest of this cutting edge (about 85%) does not participate in the destruction of the rock, and therefore does not wear out.

In 2013, Smith Beats, part of the Schlumberger Corporation, USA, published an advertising presentation in Russian for Russian drillers. One of its sections is called “A New Revolution in the Durability of PDC Cutters” (“Presentation “Creation and Application of Rotary Cutters in Various Drilling Areas” [5]. This bit design was taken as a prototype.

In this presentation, it was reported about the creation of a rotating PDC cutter in the bits presented by this company - ONIX 360. The number 360 in the designation of the bit corresponds to the possibility of continuous rotation of the cutting edge of the PDC cutter around its axis - all 360 degrees. The presentation does not contain specific design features that ensure the implementation of such a rotation of the cutter during drilling, but it mentions the significant advantages of the scheme, in which it is no longer a separate limited section of the length of the cutting edge of the cutter that is subjected to loading, but the entire edge. The presentation says that the use of ONIX - 360 bits provided a sharp increase in average penetration.

However, along with an increase in the overall performance of this bit due to rotating cutters, a new negative property was revealed in drilling - the impact strength of diamond plates and carbide substrates sharply decreased. This happened due to the fact that with the previously used method of fixed fixing of PDC cutters, there were no gaps between the walls of the holes for the cutter and the cutter itself. These gaps were filled with solder or eliminated with a pair of clamping sleeves, in each of the four analogues shown. This excluded impact contacts between the hole wall and the cutter. The practice of using in our country bits 0NIX - 360 of the company "Smith Beats" with rotating PDC cutters showed that with the gaps that appear, which are necessary for the rotation of the cutters, due to the transverse oscillations of the string and the bit, harmful additional lateral shear shock loads occur, under which the resistance diamond cutters is significantly reduced. Therefore, the damping of these continuous lateral shocks and vibrations is one of the important ways to increase the durability and performance of PDC bits with moving cutters.

The purpose of developing a new design is to create dampers-shock absorbers on the calibrating surfaces of the blades of diamond bits, which make it possible to reduce the amplitude of the transverse oscillations of the bit due to their damping. Damping calibrating PDC cutters should provide a reduction in the amplitude of harmful lateral shear impacts on the main cutters of the PDC blades that destroy the rock at the bottom.

This goal 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 rock cutting and calibrating surfaces of the blades with PDC cutters placed in them, in which between the ends of the PDC calibrating cutters with a diameter D and the bottom of the holes under them, flat dampers-shock absorbers of a mechanical type are installed, with a thickness "a" in the expanded state, and a thickness "b" in the maximum compressed state, with the magnitude of the amplitude of the possible axial movement of the PDC calibrating cutter at maximum compression damper-shock absorber "c". On the side surface of each carbide substrate of the PDC calibrating cutter, an annular groove of semicircular cross-section with a radius R1 is made, with a symmetry plane at a distance L from the end of the PDC calibrating cutter; on the wall of each hole for the PDC calibrating cutter, at a distance from the bottom of the hole, an annular groove of a semi-oval cross section is made with a width L3=2R1+"c", a depth and lateral radius fillets along both edges of the semi-oval, with the same radii R1, and its edge is from the side of the top of the PDC calibrating cutter located opposite the edge of the groove of a semicircular cross section. Both annular grooves form a joint annular cavity, into which, through a round mounting hole with a diameter of d1=2R1, on the outside of the side surface of the blade, a floating annular steel stopper of circular cross section, with a diameter d corresponding to the diameter d1 of the mounting hole, is inserted, sharpened at one end and flat on the other.

At the inlet of the mounting hole, after installing the steel ring stopper, a protective cover can be installed.

The boundaries of the location and dimensions of the damper-shock absorber, annular grooves of semicircular and semi-oval cross-section, diameters d and d1, the diameter of the calibrating cutter PDC D, are related by the following relationships: the largest diameter of the groove with a semi-oval cross section on the wall of the hole for the cutter D1=D+2R1; the smallest diameter of the semicircular groove D2=D- -2R1; distance L from the end of the cutter to the plane of symmetry of the groove with a semicircular cross section; the distance from the bottom of the hole to the plane of symmetry of the semicircular groove in the expanded state of the damper-shock absorber L1=L+а; the distance from the bottom of the hole to the plane of symmetry of the groove with a semicircular cross section in the compressed state of the damper-shock absorber L2=L+b; semi-oval groove width L3=2R1+с; the value of the maximum compression amplitude of the damper-shock absorber c=a-b.

The proposed design of the bit is illustrated by drawings, in which Fig. 1 is a side view of the proposed PDC bit, FIG. 2 - part of the enlarged cross-section of the bit A - A along the axis of symmetry of one of the peripheral dampers-shock absorbers, calibrating cutters PDC, with the position of the calibrating cutter PDC and damper-shock absorber in the expanded state, Fig. 3 - the same cross section A - A with the position of the PDC calibrating cutter and the damper-shock absorber in the most compressed state, fig. 4 is a diagram of the installation of a floating annular steel stopper, FIG. 5 - option for installing a protective cover.

In FIG. 1 positions are marked: 1 - bit body, 2 - PDC rock-cutting cutters on protruding blades, 3 - PDC calibrating cutters, 4 - body blade, 5 - cavities for flushing the bottom hole from cuttings, 6 - grooves on the body for "make-up-breakout" bits during its fastening, 7 - conical thread for connecting the bit to the drill string.

In FIG. 2 the elements shown in FIG. 1, as well as new positions are marked: 8 - the diametrical surface of the bit blade, 9 - the wall of the flushing cavity 5, the direction of the section plane B - B, passing through the plane of symmetry of one of the PDC calibrating cutters in the position of the maximum expanded damper-shock absorber, 10 - floating annular steel stopper, 11 - wall of the hole for the PDC gauge cutter, 12 - end face of the PDC gauge cutter, 13 - end face of the hole for the PDC gauge cutter, 14 - shock absorber in the expanded state, 15 - semi-circular radial groove, 16 - semi-oval annular groove, 17 - side surface of the PDC sizing cutter, 18 - hole for installing a floating annular steel stopper 10, the letters are: R1 - both lateral radius fillets in the cross section of the semi-oval groove 16; D is the diameter of the PDC calibrating cutter, D1 is the maximum diameter of the semi-oval annular groove on the wall of the hole for the calibrating PDC cutter, d is the diameter of the floating annular stopper, the letters B - B indicate the longitudinal section along the symmetry plane of the radial semicircular groove 15 with radius R1.

In FIG. 3 the elements shown in FIG. 1 and 2, as well as new positions are indicated: 19 - damper-shock absorber in the most compressed state, the letter L3 indicates the width of the semi-oval annular groove on the wall of the hole for the PDC calibrating cutter; D2 is the inner diameter of a semicircular groove on a carbide substrate.

In FIG. 4. The same numerals designate the elements shown in FIG. 1, 2, 3, as well as new positions are marked: 20 - pointed lead-in end of the rod 10, 21 - flat end of the floating locking rod 10, 22 - mandrel for installing a floating steel locking rod; the letter denotes d1 - the diameter of the mandrel is 22.

In FIG. 5 the elements shown in FIG. 1, 2, 3, 4, and also marked with new ones: 23 - protective cover of the hole, which prevents the possibility of cuttings getting into the friction zone of the locking unit, 24 - stop step on the protective cover, 25 - gap between the cylindrical surface of the PDC calibrating cutter and the wall of the hole under it, are marked with letters; d2 is the diameter of the protective cap 23, the letter "e" denotes the central angle between the ends of the floating annular steel locking rod 10 after it is placed in a position that prevents contact with the rod 10 or with the protective cap 22.

To eliminate the obstacle to the constant rotation of the PDC floating calibrating 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 a floating annular steel locking rod, it is necessary to use ductile steel with a minimum carbon content, for example, domestic st. 10. Such a sufficiently plastic material facilitates the entry of a straight rod into the annular space formed by both annular grooves 15 and 16, and also ensures that it remains permanently in the form of a curved part of the floating ring during the entire drilling time. In order to exclude the possibility of contact of the floating annular steel stop rod with the mounting mandrel or protective cover of the hole, its length is limited by the central angle, for example, within e=280-300 degrees. The shank diameter must be selected to allow for clearance in the selected fit required during installation and to work inside the locking assembly while drilling. The end working surface of the contact of the PDC calibrating cutter, calibrating the borehole wall, can have any shape, from flat to curved. To protect the cavity of the floating annular steel locking device from the ingress of sludge, any known embodiment of the protective cover for the inlet and its fastening can be used, for example with a stop shoulder and using welding, as shown in Fig. 5.

The presence of a reciprocal joint annular space formed by annular adjacent grooves of semi-oval 16 and semi-circular 15 cross-section, with an annular steel locking lock rod installed, allows the PDC calibrating cutter to rotate around its axis, and in the event of a sudden shock load on it during drilling, additionally move along this axis from one extreme position to another, compressing, and then allowing the mechanical damper-shock absorber to fully decompress. At the same time, the instantaneous shock and vibration loads are significantly reduced, which means that the amplitude of the destructive transverse vibrations of the string and bit is reduced.

As such a mechanical damper-shock absorber, it is proposed to use, for example, a flat shape in the form of a “tablet” that fits in the space between the end 12 of the calibrating cutter of the PDC cutter and the bottom 13 of the hole for the calibrating PDC cutter, made of any elastic material (for example, rubber ), capable of absorbing and permanently damping the shock load.

In domestic and foreign drilling practice, near-bit shock absorbers (bottomhole dampers) have been mastered and successfully used, which are installed as part of the drill string between the bit and drill collar to dampen longitudinal and transverse vibrations that occur when the bit is operating at the bottom of the well [6] (A.G. Kalinin, "Drilling oil and gas wells", textbook for the Higher School, TsentrLitNefteGaz, Moscow, 2008, pp. 116, 266-267.

The energy intensity of the damping device is determined by the largest amount of potential energy that can be accumulated by the elastic element of the damper. The damping capacity is understood as the proportion of irreversibly absorbed energy. Some grades of technical rubber per cycle can absorb 40-70 percent of the energy instantly acting on the damper. The material, thickness and diametrical dimensions of the recommended flat dampers for PDC bits of various diameters for drilling rocks of various hardness should be selected individually.

Installation of the floating annular steel locking rod 10 in the joint annular channel formed by both annular grooves 15 and 16 is carried out as follows. Depending on the dimensions of the PDC calibrating cutter, for which a straight locking rod is made, its dimensions are assigned, as well as the necessary dimensions for making both annular grooves 15, 16 and the inlet d1 for mounting the locking rod 10. For ease of installation, as mentioned above, its lead-in end should have a smooth anti-seize shape, and the opposite end should be a flat shape, providing maximum support to the end face of the driven mounting mandrel 22, upon impact on which the process of deepening and bending occurs when the rod 10 is installed. curved round shape during the entire working time of the PDC calibrating cutter.

To reduce the braking effect of friction that prevents rotation and axial movement of the PDC gauge cutter during drilling, the outer contact surfaces of the carbide substrate of the PDC gauge cutter 2 and locking rod 10 can be coated with any known anti-friction coatings or lubricants, such as molybdenum disulfide. Before installation, the straight locking rod 10 is hammered into the hole 17 with the necessary force, and then, using a mandrel calibrated in length, it is sent to the position shown in Fig. 4. The entire volume of the rod is completely (up to the stop of the mandrel), is installed inside the joint annular space and becomes a stopper that limits the axial movement of the PDC calibrating cutter in both directions. At the same time, the stopper cannot prevent its rotation around its axis, even with a relatively small torque created by the sliding of the edges of the PDC calibrating cutters along the surface of the borehole wall, and also does not prevent the axial movement of the PDC calibrating cutter during sudden compression of the damper, which partially absorbs the energy of impacts perceived cutter during drilling [6].

The present invention allows to solve the problem and significantly improve the performance of PDC diamond bits with shock absorbers.

SOURCES OF INFORMATION

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

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

3. "Diamond bit with mechanically fastened cutters", Bogomolov R.M., Kinyaev A.V., Krylov S.M. and others. Patent of the Russian Federation No. 2536901, class. E21B 10/573, cl. F21C35/197. 2014.

4. "Drill bit with PDC cutters" Bogomolov R.M. Patent R.F. No. 2735319 class. Е21В 10/43.201

5. Presentation "Creation and application of rotating cutters in various areas of drilling." "A new revolution in PDC cutter durability". Smith Beats (USA), Schlumberger Corporation. 2013.

6. A.G. Kalinin. "Drilling of oil and gas wells". Textbook of the Higher School. CenterLitNefteGas, M. 2008, p. 115.

Claims (1)

PDC drill bit with shock absorbers on its diameter, 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 rock cutting and calibrating surfaces of the blades with PDC cutters located in them, different by the fact that between the ends of the PDC calibrating cutters with a diameter D and the bottom of the holes under them there are flat dampers-shock absorbers of a mechanical type with a thickness "a" in the expanded state and a thickness "b" in the maximum compressed state with the magnitude of the amplitude of the possible axial movement of the PDC calibrating cutter at maximum compression damper-shock absorber - "c"; on the side surface of each carbide substrate of the PDC calibrating cutter, an annular groove of a semicircular cross section with a radius R1 and a cross section with a symmetry plane at a distance "L" from the end of the PDC calibrating cutter is made; on the wall of each hole for the PDC calibrating cutter, at a distance from the bottom of the hole, an annular groove of a semi-oval cross-section is made with a width L3=2R1+с, a depth and lateral radius fillets along both edges of the semi-oval with the same radii R1, and its edge is on the side of the top of the PDC calibrating cutter located opposite the edge of the groove of a semicircular cross section; both annular grooves form a joint annular cavity, into which, through a round mounting hole with a diameter of d1 = 2R1 outside the side surface of the blade, a floating annular steel stopper of circular cross section with a diameter of d, corresponding to the diameter d1 of the mounting hole, is pointed at one end and flat at the other ; a protective cover can be installed at the inlet of the mounting hole after installing the steel ring stopper.

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