CN111236848B

CN111236848B - Controllable electromagnetic drive type impact-scraping composite drill bit and method

Info

Publication number: CN111236848B
Application number: CN202010052493.9A
Authority: CN
Inventors: 谢松; 蔡灿; 杨迎新; 任海涛; 李邦润; 曹煜磊
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2021-07-20
Anticipated expiration: 2040-01-17
Also published as: CN111236848A

Abstract

The invention discloses a controllable electromagnetic drive type impact-scraping cutting composite drill bit and a method, wherein the controllable electromagnetic drive type impact-scraping cutting composite drill bit comprises a drill bit body, a fixed cutting structure and an impact cutting structure which are arranged on a drill bit body, and a power supply and energy storage structure, the impact cutting structure comprises an impact guide pipe, a punch and impact cutting teeth, the impact cutting teeth are fixedly connected to the tail end of the punch, the punch slides or impacts in a sliding mode relative to the drill bit body, the power supply and energy storage structure comprises a rotatable impeller, a motor, a capacitor and a control chip for controlling discharge frequency, and a matched using method is provided. Compared with the conventional PDC drill bit, the PDC drill bit disclosed by the invention can be used for pre-crushing rock, improving the rock crushing efficiency, slowing down the abrasion speed of teeth and relieving the stick-slip effect of the PDC drill bit in the drilling process. Compared with the traditional impact drill bit, the invention can control the impact frequency, automatically store energy, has simple structure and can effectively improve the rock breaking efficiency of drilling.

Description

Controllable electromagnetic drive type impact-scraping composite drill bit and method

Technical Field

The invention relates to the technical field of drilling tools, in particular to a drill bit, and specifically relates to a controllable electromagnetic drive type impact-scraping composite drill bit and a method.

Background

With the continuous deepening of oil and gas exploration and development, deep wells and ultra-deep wells are increased, and the situations of strata with high rock hardness, low rock drillability and high rock abrasiveness are increased in the drilling process. Because the stratum conditions encountered in the drilling process are increasingly complex, the mechanical drilling speed is greatly reduced, the drilling tool is increasingly worn, and factors such as underground high temperature, high pressure and the like are added, the drilling tool is easy to break down in the drilling process of deep wells and ultra-deep wells, and the development speed and the development cost of oil and gas fields are greatly influenced.

Drill bits are rock breaking tools used in drilling operations to break rock and form wellbores. The drill bits used in the current drilling engineering mainly include tricone bit, polycrystalline diamond compact bit (i.e., PDC bit) and percussion bit (also called as rotary percussion bit or drill bit).

The tricone bit mainly breaks rock in an impact crushing mode, the applicable stratum range is wide, but the energy utilization rate is not high, the rock breaking efficiency is relatively low, and the mechanical drilling speed is low. Especially when drilling deep hard-to-drill formations, it is difficult for the teeth to push into the formation and form effective fractures. The life of a tri-cone bit is largely limited by the life of the bearings. Because the pinch roller drill bit usually needs very big weight of boring when creeping into, so the load that the bearing bore is also bigger, simultaneously because the pinch roller during operation, the tooth is eaten the rock in turn, can produce great axial vibration to ground bottom operational environment is complicated changeable, hardly guarantees the leakproofness of bearing, thereby these all to a great extent have restricted the life-span of bearing thereby influence roller bit's life-span.

The PDC drill bit is used for shearing and crushing rocks by means of a polycrystalline diamond compact (PDC teeth for short), the rock breaking efficiency and the mechanical drilling speed of the PDC drill bit in soft to medium-hard formations are obviously higher than those of a tricone drill bit, along with the development of the polycrystalline diamond compact, the PDC drill bit is used more and more in drilling engineering, the proportion is larger and larger, and the PDC drill bit is still difficult to adapt to formations with high rock hardness, drillability and high abrasiveness in deep wells and ultra-deep wells. For the PDC drill bit, under the condition that the rotating speed and the bit pressure of the drill bit are the same, the rock breaking efficiency of the drill bit mainly depends on the capability of the PDC teeth to bite into rock, and the larger the depth of the PDC teeth to bite into the rock, the higher the rock breaking efficiency of the drill bit is. The main disadvantages of PDC bits are: first, at higher rock strengths or hardness, PDC teeth are more difficult to bite into the rock to create an effective scrape cut, and particularly, as PDC teeth wear, the teeth are more difficult to bite into the formation, and the rate of penetration of the drill bit is dramatically reduced. Secondly, during the process of continuously cutting rock, the PDC tooth can reach a relatively high temperature due to heat generated by severe friction, and when the temperature exceeds a limit, the wear rate of the PDC tooth obviously increases, thereby causing a thermal wear phenomenon (when the working temperature of the PDC tooth is higher than a certain temperature, the phenomenon that the wear resistance of the PDC tooth obviously decreases is called the thermal wear phenomenon of the PDC tooth). Thirdly, the wear rate of the PDC teeth in different radial regions of the PDC drill bit is significantly different, and the wear rate of the cutting teeth in the outer region (particularly, the outer 1/3 region of the bit radius) of the bit is significantly faster than that of the teeth in the central region, so that the wear balance of the cutting teeth is poor, thereby reducing the overall performance of the bit.

The percussion drill bit is a fixed tooth rock breaking tool used in percussion drilling and matched with a down-the-hole hammer. The structure of the percussion and rotary drill bit is similar to that of a PDC drill bit, no movable part is arranged on the drill bit, and a certain number of cutting teeth are arranged on the drill bit body. The difference is mainly as follows: the cutting elements of PDC bits are primarily PDC teeth, while the cutting elements of impulse bits are primarily cemented carbide or diamond composite teeth. The rock breaking mechanism of the percussion bit is significantly different from the crushing mechanism of the roller cone bit and the cutting mechanism of the PDC bit. The impact rotary drill bit can crush the rock at the bottom of the well by means of the instantaneous impact force of the teeth. The upper end of the percussion-rotary drill bit is connected with a down-the-hole impactor, when the down-the-hole impactor works, a hammer of the down-the-hole impactor reciprocates under the action of drilling fluid or circulating gas to periodically impact the drill bit or the drill bit, so that a pulse impact load is generated, and rocks are crushed under the action of the pulse impact load of teeth. Because the impact load of the drill bit depends on the down-the-hole hammer, no large weight is applied during the operation of the percussion and rotary drill bit. Generally, the rotary percussion drill bit can achieve high rock breaking efficiency when drilling in brittle formations, particularly hard brittle formations. In addition, in the easily inclined stratum with a larger stratum inclination angle, the drilling of the percussion bit is adopted, which is beneficial to reducing the well inclination tendency.

The conventional PDC drill bit has the problems of stick-slip, rebound and vibration and the like in a complex and difficult-to-drill stratum at present, and the problems cause the premature failure of drilling equipment and seriously affect the service life of a drilling tool and the drilling cost.

Research shows that the stick-slip effect of the PDC drill bit in the drilling process can be effectively relieved by applying the high-frequency axial impact load, the rock can be pre-crushed by applying the axial impact load, the proper impact frequency is favorable for generating a resonance phenomenon with the rock, the crushing volume is increased, the rock breaking efficiency is improved, and the stick-slip vibration problem of the PDC drill bit in the drilling process is relieved.

A great deal of research has been carried out on underground rock breaking tools at home and abroad, and various rock breaking tools such as a torsion impactor, a hydraulic jet impactor, a self-excitation type torsion impact tool, an axial and circumferential composite impact tool, a hydraulic rotary impact tool and the like have been designed and developed. For these existing research results, on one hand, the existence of the impact load generator makes the drilling tool too long, and on the other hand, the impact load is transmitted to the rock through the PDC cutting teeth, so that the stress of the cutting teeth in the drilling process is more complicated, the service life of the cutting teeth is seriously influenced, and the drilling time and cost are increased.

As shown in the prior art provided by the chinese invention with publication No. CN102678055B, the impact energy of the conventional impact-scraping composite drill bit is supplied from the outside, and a matched impactor needs to be provided, which results in a long drill bit, which is not favorable for drilling a directional well, and has the problems of severe abrasion of the connection part and low reliability. Compared with the traditional impact-scraping composite drill bit, the composite drill bit can realize self-powered energy storage, impact is driven through electromagnetism, the structure is simple, the drill bit is short, and directional well drilling is facilitated.

Disclosure of Invention

Aiming at the problems, the invention provides the controllable electromagnetic drive type impact-scraping cutting composite drill bit and the method, which can effectively improve the drilling efficiency, have simple structure, small occupied space and convenient assembly, disassembly and processing, do not need a separate external energy supply mechanism and are greatly helpful for improving the drilling efficiency.

The technical scheme of the invention is as follows:

a controllable electromagnetic drive type impact-scraping cutting composite drill bit comprises a drill bit body, wherein a plurality of fixed cutting structures are arranged on the drill bit body, a plurality of impact cutting structures are further arranged on the drill bit body, each impact cutting structure comprises an impact guide pipe and an impactor, the impacters are arranged in the guide pipes, the outer end parts of the guide pipes are provided with limiting mechanisms, and the side surfaces of the impacters are provided with clamping blocks matched with the limiting mechanisms; an impact driving device is arranged behind the impact cutting mechanism.

Preferably, the impactor comprises a punch and impact cutting teeth connected to the top of the punch, the punch is of a cylindrical structure, and a clamping block in the middle of the punch is an annular anti-falling boss; the guide pipe is of a tubular structure and comprises a main pipe section and a circle of widening section arranged at the top of the main pipe section, the inner diameter of the widening section is smaller than that of the main pipe section, the outer diameter of the widening section is larger than that of the main pipe section, and the widening section is used as a limiting mechanism and matched with the anti-falling boss; the upper part of the inner side of the main pipe section is provided with a front protection spring, and the lower part of the inner side of the main pipe section is provided with a rear protection spring;

and a sealing device is arranged between the punch and the impact guide pipe.

Preferably, an electromagnetic coil is arranged on the outer side of the main pipe section of the impact guide pipe, and a power supply and energy storage structure is further arranged in the drill bit body and connected to the electromagnetic coil;

the electromagnetic coil is of a double-spiral surrounding structure and is wound on the outer side of the main pipe section.

Preferably, the power supply device is arranged in the drill bit body, a flow channel is arranged in the middle of the drill bit body, and the power supply device is arranged in the flow channel;

the power supply and energy storage structure comprises a power generation device, an electric storage device and a conducting device, wherein the conducting device is connected to the impactor; the power generation device is arranged in the flow channel and generates power through fluid impact of the flow channel; the power storage device is arranged below the power generation device and stores the electric energy generated by the power generation device.

Preferably, the power generation device is an impeller and a motor, the power storage device is a circuit board, and a capacitor, a control chip and a storage battery are arranged on the circuit board; the conductive device is an anti-interference waterproof wire;

and a sealing waterproof structure with the outside is arranged between the power supply and energy storage structures.

Preferably, the fixed cutting structure is a blade, the number of the blades is 3, and each blade is provided with at least one row of fixed cutting teeth; the number of the impact cutting structures is 3, the impact cutting structures are arranged between two adjacent blades, and the impact cutting structures are arranged on the crown part of the drill body.

Preferably, the fixed cutting teeth and the impact cutting teeth are made of any one of polycrystalline diamond compact cutting teeth, thermal-stability polycrystalline diamond cutting teeth, natural diamond cutting teeth, diamond-impregnated cutting blocks, diamond-impregnated cutting teeth, hard alloy cutting teeth, diamond-reinforced hard alloy cutting teeth, cubic boron nitride cutting teeth and ceramic cutting teeth.

Preferably, the tooth profile of the impact cutting tooth is any one of a cone-ball tooth, a wedge-shaped tooth, a spherical tooth, an edge wedge tooth and a spoon-shaped tooth.

Preferably, the impact cutting tooth is arranged in radially overlapping coverage with the fixed cutting tooth.

Preferably, the punch is provided with a front protection spring and a rear protection spring to prevent direct contact between the punch and the impact guide tube.

A working method of a controllable electromagnetic drive type impact-scraping composite drill bit comprises the following steps:

1) installing a controllable electromagnetic driving type impact-scraping composite drill bit in place, putting the drill bit into the underground, starting drilling operation, and arranging a water hole at the tail end of a flow channel of a drill bit body;

2) when drilling fluid sent from the well through the interior of the drill rod flows through the impeller from the drill bit body, the impeller rotates to drive the motor to generate electric energy, and the electric energy is transmitted to the storage battery and stored in the storage battery;

3) the storage battery charges the capacitor under the control of the control chip, the capacitor starts to accumulate electric energy, when the electric energy accumulated in the capacitor reaches a certain degree, the control chip controls the capacitor to discharge, and the electric energy is transmitted to the electromagnetic coil through the electric energy transmission channel;

4) when current flows through the coil, magnetic force is generated in the impact guide pipe, the punch is ejected out, and the target rock is impacted.

The invention has the advantages that:

(1) compared with the single roller cone-PDC mixed drill bit in the prior art, the impact structure occupies a smaller space on the drill bit, thereby being beneficial to the structural design of the drill bit and prolonging the service life of the drill bit.

(2) Compared with the drill bit with the impactor in the prior art, the power supply and energy storage structure in the composite drill bit provided by the invention can realize self-power generation and energy storage through drilling fluid, has a simple impact structure, does not need an additional matched impact tool to input external energy, has a small size, and is very favorable for drilling a directional well.

(3) The composite drill bit can use different impact frequencies according to different rock strata adjustment before going into the well, and the impact frequencies can be adjusted through a control chip.

(4) In the stratum with stronger brittleness, the impact effect of the composite drill bit is more obvious.

(5) Compared with the traditional impact-scraping composite drill bit, the high-frequency impact force is generated through electromagnetism, the structure is simple, the number of connecting parts is small, and the reliability is high.

(6) When an impact cutter fails or is less efficient for a variety of reasons, the fixed cutting element may still function properly.

(7) Compared with a conventional PDC drill bit, the PDC drill bit can obviously reduce the difficulty of the cutting teeth in entering the rock and the energy consumption for breaking the rock, and can achieve higher rock breaking efficiency when a stratum with higher hardness is drilled.

(8) Because the PDC cutting teeth have lower energy consumption when cutting at the place with the crushing pit, the generated friction is smaller, and the thermal abrasion phenomenon is greatly improved.

(9) When impact cutting teeth are arranged in the radial outer area of the drill bit, the abrasion of the fixed cutting teeth in the outer area of the drill bit is greatly improved due to the existence of impact rock breaking, the synchronism of the abrasion of the core of the drill bit and the external cutting teeth is favorably improved, and the comprehensive performance of the drill bit is improved.

(10) The drift and strike the cutting teeth in this patent can be followed and to be slided for the drill bit body in the direction of strikeing the stand pipe, and the impact force can not transmit the cutting teeth with the vibration that the impact brought on, is favorable to prolonging the life of cutting teeth.

Drawings

FIG. 1 is a schematic view of the external perspective of a controllable electromagnetic drive percussion-scraping composite drill bit of the present invention;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a cross-sectional view of a controllable electromagnetic driven percussion-scrape cutting composite drill bit;

FIG. 4 is a schematic view of a punch and an impact cutting tooth in the impact cutting structure of the present invention;

FIG. 5 is a cross-sectional view of an impact guide tube in the impact cutting structure of the present invention;

FIG. 6 is a schematic view of the electromagnetic coil in the impact cutting structure of the present invention, in which a is a front view of the outer appearance and b is a sectional front view;

FIG. 7 is a schematic external perspective view of an impeller in the energy storage and power supply structure of the present invention;

FIG. 8 is a schematic view of the internal components of the impeller of the present invention;

FIG. 9 is a schematic view of circumferential tooth arrangement of a composite drill bit;

FIG. 10 is a schematic view of radial tooth arrangement of a composite drill bit.

The labels in the figure are:

1-a bit body;

2-a blade;

21-fixed cutting teeth;

3-impact cutting teeth;

31-1# impact cutter; 32-2# impact cutter; 33-3# impact cutting teeth; 34-impact cutting tooth cutting trajectory;

4-impacting a guide pipe;

5-punching head;

6-water eye;

7-an electromagnetic coil;

8-impeller;

81-a circuit board; 811-capacitance; 812-a control chip; 813-storage battery; 82-a motor;

9-an electric energy transmission channel;

10-front protection spring;

11-rear protection spring.

Detailed Description

The present invention will be further described with reference to the following examples.

A controllable electromagnetic driving type impact-scraping cutting composite drill bit can realize automatic power supply and energy storage at the bottom of a well, reduce the use of transmission parts to improve the reliability of the drill bit, apply impact load with controllable frequency to rocks in the drilling process of a PDC drill bit, improve the rock breaking efficiency and prolong the service life of a downhole drilling tool.

As shown in fig. 1-10, a controllable electromagnetic driving type impact-scraping composite drill bit comprises a drill bit body 1 and a fixed cutting structure fixedly connected on the drill bit body 1, wherein the composite drill bit is provided with an impact cutting structure and a power supply and energy storage structure. The drill bit comprises a drill bit body 1, blades 2 extending from the drill bit body 1, a water channel between the blades 2, a water hole 6 or a nozzle, PDC cutting teeth, an impact cutting structure comprises a punch 5 for transferring impact force, impact cutting teeth 3, an electromagnetic coil 7 and an impact guide tube 4, a front protection spring 10 and a rear protection spring 11 are respectively arranged at the top and the bottom of the impact guide tube 4, a power supply and energy storage structure comprises an impeller 8 and a motor 82 arranged inside the impeller 8, and a circuit board 81, wherein the circuit board 81 comprises a capacitor 811, a control chip 812 and a storage battery 813.

The drill body, the blades 2, the blade cloth tooth surface, the water holes 6, the nozzles, the blade body contour lines, and the corresponding cutting teeth according to the present invention are concepts known in the art.

Specifically, the impeller 8 rotates under the driving of drilling fluid, the motor 82 generates electric energy to charge the capacitor 811, the control chip 812 controls the discharge frequency and the discharge magnitude of the capacitor 811, the electric energy released by the capacitor 811 is finally transmitted to a coil at the crown of the drill bit to generate a magnetic field, and the generated magnetic force ejects the ferromagnetic punch 5 out to form impact force and apply the impact force to the rock.

The fixed cutting teeth 21 on the fixed cutting structure are polycrystalline diamond compacts, and also can be thermally stable polycrystalline diamond, natural diamond and diamond-impregnated cutting teeth, and the impact cutting teeth 3 on the impact cutting structure are hard alloy teeth or hard alloy teeth with reinforced surfaces made of diamond. The tooth profile of the cemented carbide tooth used as the impact cutting tooth 3 may be a spherical tooth, a conical tooth, a wedge tooth, a side wedge tooth, and a spoon tooth, or may be a tooth of other shapes having a good impact rock breaking effect.

The impact cutting teeth 3 of the impact cutting structure may be arranged within the radial coverage of the fixed cutting structure fixed cutting teeth 21, may be arranged independently (without overlapping the radial coverage of the fixed cutting structure fixed cutting teeth 21), or may be arranged partially independently.

Preferably, the impact cutting teeth 3 of the impact cutting structure are arranged in a radial region outside one third of the drill radius.

Preferably, the impact cutting teeth 3 of the impact cutting structure are arranged within a radial region outside one half of the drill radius.

Preferably, the impact cutting teeth 3 of the impact cutting structure are arranged in a radial region outside two thirds of the drill radius.

Preferably, the impact cutting teeth 3 of the impact cutting structure are arranged in a radial area within one third of the radius of the drill bit.

The drift 5 on be equipped with and prevent falling the boss to avoid drift 5 and impact cutting tooth 3 to drop at the during operation, be equipped with leading protection spring 10 and rearmounted protection spring 11 around in the impact guide tube 4, cushion when moving to the stroke limit to drift 5, protect drift 5 with this. Wherein the punch 5 and the impact teeth are connected in a welding mode.

The controllable electromagnetic driving type impact-scraping cutting composite drill bit adopts a split structure, so that an impact structure and a power supply and energy storage structure can be separated from the composite drill bit to form an independent part. At the moment, the drill bit is formed by connecting an impact structure, a power supply and energy storage structure and a drill bit body 1, wherein the impact structure is arranged at the hollow part of the crown part of the drill bit, and the power supply and energy storage structure is arranged at the hollow part of a flow passage of the drill bit. The split structure is more favorable for manufacturing and using the composite drill bit, and all the parts can be manufactured respectively and assembled together before entering a well for use.

When drilling fluid flows through the impeller 8, the impeller 8 rotates to drive the motor 82 to generate electric energy, the electric energy is transmitted to the storage battery 813 and stored in the storage battery 813, the storage battery 813 charges the capacitor 811 under the control of the control chip 812, the capacitor 811 starts to accumulate the electric energy, after the electric energy accumulated in the capacitor 811 reaches a certain degree, the control chip 812 controls the capacitor 811 to discharge, the electric energy is transmitted to the electromagnetic coil 7 through the electric energy transmission channel 9, when current flows in the coil, magnetic force is generated in the impact guide pipe 4, the punch 5 is ejected out, and impact is carried out on target rocks. The storage battery 813 is used for storing electric energy generated by the motor 82 and continuously charging the capacitor 811, the capacitor 811 is used for storing electric energy and outputting enough electric energy to generate enough impact force, and the control chip 812 is mainly used for controlling the frequency and magnitude of discharging of the capacitor 811 to indirectly control the frequency and magnitude of the impact force.

One of the keys of the invention is: the composite drill bit can realize self power supply and self energy storage, and compared with the traditional impact tools, the composite drill bit does not need an additional matched impactor to input external energy, has a simple structure, few parts and small size, and is very favorable for drilling directional wells.

The second key point of the invention is that: when the current generated by the power supply and energy storage structure flows through the electromagnetic coil 7, a magnetic force with a sufficient magnitude is generated in the impact guide tube 4 to eject the punch 5, and the control chip 812 controls the direction of the magnetic force to realize the reciprocating motion of the punch 5, so that the target rock is impacted. The patent relies on electromagnetism to generate impact force, and the frequency and amplitude of the impact force are adjustable, which is very different from conventional impact type tools. The impact frequency and the impact size can be adjusted according to different stratums so as to achieve the optimal rock breaking effect (the traditional mechanical impact tool is single in function, poor in complex stratum applicability and unadjustable in frequency). Compared with the conventional impact-scraping composite drill bit, the internal connecting piece is fewer, and the reliability and the service life are greatly improved.

Preferably, the impact frequency may be other waveforms such as a pulse wave, a rectangular wave, and a sine wave.

Research shows that the rock has different response and destruction forms to the impact frequency of different waveforms, so that the waveform of the impact frequency can be adjusted by the control chip 812 according to different strata, and the optimal rock breaking effect is achieved.

The manner of controlling the discharge frequency and size of capacitor 811 may be chip control or other manners, and those skilled in the art may make many choices in combination with the prior art under the teaching of this specification, and these technical solutions are all within the scope of the present invention.

For a controllable electromagnetic driving type impact-scraping composite drill bit comprising the impact mechanism, the working process is as follows:

after the drill bit starts to work, drilling fluid flows through the impeller 8, the impeller 8 starts to rotate, the motor 82 is driven to generate electric energy, the electric energy is transmitted to the storage battery 813 to be stored, the storage battery 813 continuously charges the capacitor 811, the capacitor 811 starts to accumulate the electric energy under the control of the control chip 812, after the electric energy accumulated in the capacitor 811 reaches a certain degree, the control chip 812 controls the capacitor 811 to start discharging, the electric energy is transmitted to the electromagnetic coil 7 at the crown of the drill bit through a transmission channel, a magnetic field is generated, so that impact force with controllable certain frequency is generated on the punch 5 and acts on the rock, the rock is pre-crushed, a crushing pit or a pressing pit is generated, and meanwhile, the cutting teeth on the fixed cutting structure start to contact with the bottom of the well and. And circulating fluid flows through the impeller 8 and then flows out from the drill water hole 6 or the nozzle through the internal flow passage to finish the functions of cooling the cutting teeth, cleaning the drill bit, cleaning the well bottom and carrying rock debris. The fixed cutting structure and the impact cutting structure advantageously interact with each other. The cutting teeth in the fixed cutting structure of the composite drill bit are usually PDC teeth (or mainly PDC teeth), and the key point of the rock breaking efficiency of the composite drill bit is the biting effect of the PDC teeth on the rock at the bottom of a well. To increase the penetration depth of PDC teeth, only the weight-on-bit is typically increased, which is limited, and increases the weight-on-bit can exacerbate wear of the PDC teeth and reduce the working life of the drill bit. According to the technical scheme, the electromagnetic driving type impact cutting structure is introduced on the basis of the conventional PDC drill bit, so that the characteristics and advantages of an impact rock breaking mode can be effectively utilized, the rock breaking efficiency of the fixed cutting structure is remarkably improved, and the service life of the cutting teeth is remarkably prolonged. The electromagnetic driving type impact cutting structure is dependent on the pulse impact load of the impact cutting teeth 3 with controllable frequency to the rock to break the rock, so that the requirement on the working bit pressure is low, the impact effect of the 3# impact cutting teeth 3 to the rock at the bottom of the well is that individual breaking pits or pressing pits are formed in the corresponding area of the bottom of the well, the breaking pits or the pressing pits are equivalent to the generation of a certain free surface, the existence of the free surface releases the stress in the rock, the stress of the PDC cutting teeth during cutting is reduced, the penetration of the PDC teeth in the corresponding area of the fixed cutting structure to the rock at the bottom of the well is directly promoted, and meanwhile, the working load of the PDC teeth is reduced. In other words, when the cutting teeth of the fixed cutting structure are drilled on a rugged well bottom having many chipping pits, the drilling rate is significantly higher than that on a slick well bottom, and the wear rate of the cutting teeth is significantly lower than that when drilled on a slick well bottom.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A controllable electromagnetic drive type impact-scraping composite drill bit comprises a drill bit body, wherein a plurality of fixed cutting structures are arranged on the drill bit body, and the controllable electromagnetic drive type impact-scraping composite drill bit is characterized in that a plurality of impact cutting structures are further arranged on the drill bit body, each impact cutting structure comprises an impact guide pipe and an impactor, each impactor is arranged in each guide pipe, a limiting mechanism is arranged at the outer end part of each guide pipe, and a clamping block matched with each limiting mechanism is arranged on the side surface of each impactor; an impact driving device is arranged behind the impact cutting mechanism;

the impactor comprises a punch and impact cutting teeth connected to the top of the punch, the punch is of a cylindrical structure, and a clamping block in the middle of the punch is an annular anti-falling boss; the guide pipe is of a tubular structure and comprises a main pipe section and a circle of widening section arranged at the top of the main pipe section, the inner diameter of the widening section is smaller than that of the main pipe section, the outer diameter of the widening section is larger than that of the main pipe section, and the widening section is used as a limiting mechanism and matched with the anti-falling boss; the upper part of the inner side of the main pipe section is provided with a front protection spring, and the lower part of the inner side of the main pipe section is provided with a rear protection spring;

a sealing device is arranged between the punch and the impact guide pipe;

an electromagnetic coil is arranged on the outer side of the main pipe section of the impact guide pipe, and a power supply and energy storage structure is also arranged in the drill bit body and connected to the electromagnetic coil;

2. The controllable electromagnetic drive percussion-scraping composite drill bit according to claim 1, wherein the power supply device is disposed in the drill bit body, a flow passage is disposed in the middle of the drill bit body, and the power supply device is mounted in the flow passage;

3. The controllable electromagnetic drive type impact-scraping composite drill bit as claimed in claim 2, wherein the power generation device is an impeller and a motor, the power storage device is a circuit board, and a capacitor, a control chip and a storage battery are arranged on the circuit board; the conductive device is an anti-interference waterproof wire;

4. A controlled electromagnetic drive percussive-scraping composite drill bit as set forth in claim 3 wherein said fixed cutting structures are blades, there being 3 blades, there being at least one row of fixed cutting teeth on each blade; the number of the impact cutting structures is 3, the impact cutting structures are arranged between two adjacent blades, and the impact cutting structures are arranged on the crown part of the drill body.

5. A controllable electromagnetic drive percussion-scraping composite drill bit according to claim 4, wherein the material of the fixed cutter and the percussion cutter is any one of polycrystalline diamond compact cutter, thermally stable polycrystalline diamond cutter, natural diamond cutter, diamond-impregnated cutter, cemented carbide cutter, diamond-reinforced cemented carbide cutter, cubic boron nitride cutter, and ceramic cutter.

6. A controllable electromagnetic drive percussion-scraping composite drill bit according to claim 5, wherein the profile of the percussion cutting teeth is any one of cone-ball teeth, wedge-shaped teeth, spherical teeth, side wedge teeth, and spoon teeth.

7. A controlled electromagnetic driven percussion-scrape composite drill bit according to claim 6, wherein the percussion cutting teeth are in radially overlapping overlying arrangement with the fixed cutting teeth.

8. A method of operating with a controlled electromagnetic driven percussion-scrape cutting composite drill bit as claimed in claim 7, comprising the steps of: