A system and method for predicting the combined rock-breaking effect of rotational impact

Abstract

This invention discloses a system and method for predicting the combined rock-breaking effect of rotary-impact drilling, comprising: a combined rock-breaking device for simulating rotary-impact combined rock-breaking of a core sample from a formation to be predicted, based on preset rotary cutting parameters and preset impact drilling parameters, to obtain corresponding combined rock-breaking parameters; the combined rock-breaking device includes a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit; and a data processing device for calculating the rock-breaking volume after rock-breaking, using the preset rotary cutting parameters and the current drilling depth; and, based on this, calculating the specific work of core breaking, combining the combined rock-breaking parameters, the rotary shear rock-breaking energy generated by rotary cutting, and the impact rock-breaking energy generated by impact drilling, to evaluate the rock-breaking effect of the formation to be predicted. This invention achieves an effective evaluation of the rock-breaking effect under combined rock-breaking action.

Description

Technical Field

[0001] This invention belongs to the field of petroleum exploration and development, and in particular relates to a system and method for predicting the combined rock-breaking effect of rotational impact. Background Technology

[0002] As oil and gas exploration deepens, the difficulty of exploration increases, and well depths extend from shallow to deep and ultra-deep formations, making rock breaking more challenging. Rotary impact rock breaking technology is a drilling method that applies impact force to rock breaking based on rotary rock breaking, causing the drill bit to break rocks under the combined action of impact dynamic load and rotation. In recent years, various new rotary impact tools have been developed both domestically and internationally and have been widely applied in production practice. The rotary impact combined rock breaking method performs excellently in hard formations, soft formations, and formations with a combination of hard and soft materials, and its application in drilling engineering is becoming increasingly widespread. Rotary impact technology is constrained by complex process parameters; the rational selection of drilling pressure, rotation speed, impact parameters, and adaptability to the formation directly affects drilling efficiency. Field data shows that in formations where rotary impact is not well understood, problems such as tooth breakage, tooth fragmentation, severe wear of cutting teeth, and reduced drilling footage exist, significantly hindering the efficient development of oil and gas resources.

[0003] In the process of developing this invention, the inventors discovered that existing technologies have not accurately revealed the intrinsic mechanism of rotary impact combined rock breaking. Furthermore, existing indoor micro-drilling methods for determining rock drillability can only evaluate the rock breaking effect of the drill bit under single rotary shearing or impact action, and lack an effective means for indoor evaluation of the rotary impact combined rock breaking effect. Therefore, further indoor experiments are needed to verify the rotary impact rock breaking efficiency in order to determine the optimal rotary drilling parameters.

[0004] In existing technology, a horizontal torsional elastic buffer and impact rock-breaking drilling tool mainly consists of an upper connector, a seal, a roller bearing, a cylindrical elastomer, and a lower connector. The upper connector of this drilling tool is connected to the drill collar and receives the power input from the drill collar, including torque and kinetic energy. During the cutting of rock, the drill bit cuts the rock through the horizontal torsional elastic buffer of the cylindrical elastomer, continuously absorbing kinetic energy, then converting and storing it as elastic potential energy. Finally, the accumulated elastic potential energy is released in a concentrated manner to form impact kinetic energy. The instantaneously released impact kinetic energy is transferred to the lower connector, and then output to the drill bit, completing the horizontal torsional elastic buffer and impact rock-breaking drilling. This drilling tool achieves horizontal torsional elastic buffer and impact rock-breaking drilling, not only improving the drilling speed of the drilling machinery but also protecting the cutting teeth of the drill bit, protecting the drill bit, and extending its service life. However, it cannot obtain rock-breaking parameters and cannot conduct research on the impact rock-breaking mechanism.

[0005] A continuous axial impact rock-breaking hammer generates controllable pressure pulse waves at a high frequency without affecting wellbore trajectory control, enabling high-frequency impact on the drill bit. It connects directly to the drill bit, with the impact force acting directly on the drill bit body; the magnitude of the impact force is adjustable. A PDC drill bit for continuous impact rock breaking via pulse oscillation is also provided. Drilling fluid enters the PDC drill bit and flows out through the water inlet after passing through the pulse sub. A high-speed incident flow is formed through the fluid inlet of the pulse sub, flowing out after passing through the internal flow channel of the pulse sub, creating axial pulse vibrations that act on the drill bit. This impact rock-breaking drill bit utilizes the circulation of drilling fluid within the pulse sub to generate axial pulse vibrations. A hydraulically driven axial vibration impact rock breaker includes an impact mechanism sleeved on a distribution pipe and positioned opposite to the start-up fluid inlet channel. The impact mechanism comprises a start-up pipe and a hydraulically driven hammer tube. The start-up pipe is axially movable and sleeved on the distribution pipe, and the hydraulically driven hammer tube is axially movable and sleeved on the start-up pipe. Driven by the start-up pipe, the hydraulically driven hammer tube impacts the outer body of the hammer. This rock breaker applies axial vibration force to a rotary drilling bit to improve its rock-breaking efficiency and drilling speed. A rock-breaking device and its impact apparatus are also included, featuring a sealing block to prevent soil from entering the placement chamber during impact rock breaking. The sealing block has spiral grooves that connect the outside to the placement chamber, guiding lubricating oil and gas out and preventing pressure buildup in the placement chamber, thus ensuring the reliability of the impact rock breaking. This impact device, along with the aforementioned rock-breaking hammer, PDC drill bit, and rock breaker, are all effective impact rock-breaking devices, but none can obtain rock-breaking parameters, thus hindering research on the impact rock-breaking mechanism.

[0006] In addition, a high-frequency vibration impact rock breaking experimental device was proposed, which uses a drill bit with axial high-frequency vibration and a horizontally rotating rock sample to simulate the high-frequency vibration impact excitation required for rock breaking. This provides an experimental device and method for indoor simulation experiments, enabling the realization of the high-frequency vibration impact rock breaking process. Simultaneously, this experimental device breaks through the existing technology of using a drill bit to break stationary rock samples, opening up a new device and method for high-frequency vibration impact rock breaking. However, it cannot perform torque measurement or study the impact rock breaking mechanism.

[0007] In addition, a test device and experimental method for rock drillability under impact mode can simulate the rock breaking process by drill bit impact mode, providing equipment for rock drillability testing under impact conditions. The experimental method takes into account the brittle characteristics of rock during impact breaking and uses the displacement of a fixed micro drill bit to distinguish the drillability level of different rock samples. It also considers both static and dynamic impact modes of the drill bit. The test results are consistent with actual drilling conditions, but it cannot obtain the cutting force at a certain rotation speed, cannot carry out torque measurement, and also cannot conduct research on the rock breaking mechanism of impact.

[0008] An indoor drilling simulation device and evaluation method under multi-factor environment is used to simulate multi-factor condition parameters affecting drilling, such as rotational speed, drilling pressure, overburden pressure, formation pressure, and bottom hole circulation pressure, under high temperature and high pressure conditions. It evaluates the effects of different drilling fluid treatment agents and drilling fluid systems on drilling speed and bottom hole cleaning effect. However, it does not consider the drilling mode, so it cannot study the rock breaking mechanism related to the drilling mode.

[0009] A testing device and method for rock drillability testing in deep and ultra-deep wells are disclosed. The testing device can simulate the high-pressure environment of the formation at the bottom of the well and test the relationship between drilling depth and time through a displacement sensor at the micro drill bit. It can optimize drilling pressure, rotation speed, drilling fluid type, and predict drilling speed of drilling machinery. It meets the requirements of bottom-hole temperature and pressure during the simulation of deep and ultra-deep well drilling process and has the function of measuring multiple sets of rock drillability values ​​in a single deep borehole experiment. However, it cannot carry out rock breaking tests under impact to explore the impact rock breaking mechanism of deep and ultra-deep wells.

[0010] Next, a rotary adaptive impact drill bit is described. One end of the casing is threaded with an upper connector, and the other end is threaded with a load-bearing body. A central rod is mounted inside the casing via a bushing. A fluid distributor is threaded onto the top of the central rod, and the bottom end of the central rod extends to the outer end of the load-bearing body. A drill bit is threaded onto the end of the central rod extending to the outer end of the load-bearing body. During operation, the counter-torque of the central rod compresses and stores energy in a spring. The drilling fluid creates pressure in the upper connector. Under the combined action of the drilling fluid and the spring, the central rod is accelerated downwards, achieving impact rock breaking. However, this drill bit can only serve as an effective downhole impact rotary tool and is not suitable for indoor impact rotary rock breaking experiments.

[0011] A rock drillability tester under formation conditions includes a clamping mechanism, a pressure balancing mechanism, and a power mechanism. Employing an electromechanical integrated connector, it can simulate temperature, confining pressure, pore pressure, and wellbore mud pressure under formation conditions to conduct realistic and accurate rock drillability tests. It can simulate overburden confining pressure, pore pressure, and wellbore mud pressure up to 90 MPa, providing more practical guidance for drilling operations. While this device simulates the influence of various formation environmental factors on the rock's compressive strength, it cannot freely adjust experimental parameters such as drill bit rotation speed, and therefore cannot conduct indoor impact rock breaking tests at different rotation speeds. Summary of the Invention

[0012] To address the aforementioned problems, this invention provides a system for predicting the combined rock-breaking effect of rotary-impact drilling, comprising: a combined rock-breaking device for simulating rotary-impact drilling of a core sample of a formation to be predicted based on preset rotary cutting parameters and preset impact drilling parameters, thereby obtaining corresponding combined rock-breaking parameters; the combined rock-breaking device including a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit; and a data processing device for calculating the rock-breaking volume after rock-breaking is completed, using the preset rotary cutting parameters and the current drilling depth; and based on this, calculating the specific work of the core sample by combining the combined rock-breaking parameters, the rotary shear rock-breaking energy generated by rotary cutting, and the impact rock-breaking energy generated by impact drilling, to evaluate the rock-breaking effect of the formation to be predicted.

[0013] Preferably, the impact drilling unit includes a vibrator, which is used to apply external excitation to the drill rod connected to the drill bit according to the preset impact drilling parameters, thereby providing vibration impact excitation to the drill bit. The preset impact drilling parameters include, but are not limited to, impact waveform, impact force, impact amplitude and impact frequency.

[0014] Preferably, the impact drilling unit further comprises: a vibrator bracket for fixing the vibrator to a bearing plate, so that the vibrator remains in the same position during rock breaking; and a floating plate fixed to the drill rod and connected to the vibrator to ensure that the drill rod receives stable external excitation.

[0015] Preferably, the system further includes: a core clamp for holding and fixing the core, wherein the core clamp adopts a four-jaw arc-shaped adjusting rod, wherein the drill bit has a plurality of cutting tooth mounting slots, and by configuring different numbers of cutting teeth on the drill bit, each cutting tooth is arranged in a designated mounting slot, thereby forming different blade structures on the drill bit, wherein the cutting teeth adopt PDC blades.

[0016] Preferably, the data processing device includes a rock-breaking volume calculation unit, which is used to extract the number of cutting teeth and the drill bit diameter from the preset rotary cutting parameters, and calculate the rock-breaking volume using the number of cutting teeth, the drill bit diameter, and the current drilling depth, wherein the rock-breaking volume is calculated using the following expression:

[0017]

[0018] Where V represents the rock breaking volume, N represents the number of cutting teeth, D represents the drill bit diameter, d represents the cutting tooth diameter, θ represents the cutting tooth back slope angle, h represents the drilling depth, and β represents the cutting tooth side slope angle.

[0019] Preferably, the data processing device further includes: a rotary shear rock-breaking energy calculation unit, which is used to extract the drill bit cutting force data from the composite rock-breaking parameters, and the drill bit diameter and cutting speed from the preset rotary cutting parameters, and calculate the rotary shear rock-breaking energy using the drill bit cutting force data, the drill bit diameter, and the cutting speed, wherein the rotary shear rock-breaking energy is calculated using the following expression:

[0020]

[0021] Among them, W sr This represents the rotational shear rock-breaking energy per unit time, where F represents the drill bit cutting force, D represents the drill bit diameter, and n represents the cutting speed.

[0022] Preferably, the data processing device is further configured to use the mass of rock fragments in the composite rock breaking parameters to obtain the kinetic energy of the rock fragments that convert the rock core into rock fragments during the rock breaking process, and to use the kinetic energy of the rock fragments to correct the impact rock breaking energy, thereby evaluating the rock breaking effect of the formation to be predicted based on the corrected impact rock breaking energy.

[0023] Preferably, the kinetic energy of the debris is calculated using the following expression:

[0024]

[0025] Among them, W d Let n represent the kinetic energy of the rock fragments, n represent the cutting speed, m represent the mass of the rock fragments, and D represent the drill bit diameter.

[0026] Preferably, the data processing device further includes: a rock breaking specific energy calculation unit, which is used to obtain the total rock breaking energy in the rotary impact combined rock breaking process by utilizing the rotary shear rock breaking energy generated by rotary cutting and the impact rock breaking energy generated by impact drilling, and then use the total rock breaking energy and the rock breaking volume to obtain the rock breaking specific energy, wherein the rock breaking specific energy is calculated using the following expression:

[0027]

[0028] Where E represents the specific work of breaking, W t V represents the total rock-breaking energy, and V represents the rock-breaking volume.

[0029] On the other hand, the present invention also provides a method for predicting the combined rock-breaking effect of rotary-impact drilling. The method includes: a combined rock-breaking device performing a rotary-impact drilling simulation on a core sample of the formation to be predicted based on preset rotary cutting parameters and preset impact drilling parameters to obtain corresponding combined rock-breaking parameters. The combined rock-breaking device includes a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit. After rock-breaking is completed, a data processing device uses the preset rotary cutting parameters and the current drilling depth to calculate the rock-breaking volume. Based on this, and combining the combined rock-breaking parameters, the rotary shear rock-breaking energy generated by rotary cutting, and the impact rock-breaking energy generated by impact drilling, the specific work of the core sample is calculated to evaluate the rock-breaking effect of the formation to be predicted.

[0030] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0031] This invention proposes a system and method for predicting the combined rock-breaking effect of rotary-impact drilling. The system is based on preset rotary cutting parameters and preset impact drilling parameters for simulating rotary-impact drilling. It utilizes a rotary cutting unit and an impact drilling unit working together to provide the drill bit with rotary cutting torque and vibration impact excitation for simulation. After the simulation, the rock breaking specific work under the combined rotary-impact drilling conditions is calculated using the measured combined rock-breaking parameters, as well as the preset rotary cutting and impact drilling parameters. This allows for effective evaluation of the combined rock-breaking effect based on the breaking specific work. This invention achieves effective evaluation of the rock-breaking effect under combined rock-breaking action, providing a crucial basis for optimizing drilling parameters and for personalized drill bit design and selection.

[0032] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram of the overall structure of a system for predicting the combined rock-breaking effect of rotational impact according to an embodiment of this application.

[0035] Figure 2 This is a step diagram of a method for predicting the combined rock-breaking effect of rotational impact according to an embodiment of this application. Detailed Implementation

[0036] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0037] Furthermore, the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0038] As oil and gas exploration deepens, the difficulty of exploration increases, and well depths extend from shallow to deep and ultra-deep formations, making rock breaking more challenging. Rotary impact rock breaking technology is a drilling method that applies impact force to rock breaking based on rotary rock breaking, causing the drill bit to break rocks under the combined action of impact dynamic load and rotation. In recent years, various new rotary impact tools have been developed both domestically and internationally and have been widely applied in production practice. The rotary impact combined rock breaking method performs excellently in hard formations, soft formations, and formations with a combination of hard and soft materials, and its application in drilling engineering is becoming increasingly widespread. Rotary impact technology is constrained by complex process parameters; the rational selection of drilling pressure, rotation speed, impact parameters, and adaptability to the formation directly affects drilling efficiency. Field data shows that in formations where rotary impact is not well understood, problems such as tooth breakage, tooth fragmentation, severe wear of cutting teeth, and reduced drilling footage exist, significantly hindering the efficient development of oil and gas resources.

[0039] In the process of developing this invention, the inventors discovered that existing technologies have not accurately revealed the intrinsic mechanism of rotary impact combined rock breaking. Furthermore, existing indoor micro-drilling methods for determining rock drillability can only evaluate the rock breaking effect of the drill bit under single rotary shearing or impact action, and lack an effective means for indoor evaluation of the rotary impact combined rock breaking effect. Therefore, further indoor experiments are needed to verify the rotary impact rock breaking efficiency in order to determine the optimal rotary drilling parameters.

[0040] In existing technology, a horizontal torsional elastic buffer and impact rock-breaking drilling tool mainly consists of an upper connector, a seal, a roller bearing, a cylindrical elastomer, and a lower connector. The upper connector of this drilling tool is connected to the drill collar and receives the power input from the drill collar, including torque and kinetic energy. During the cutting of rock, the drill bit cuts the rock through the horizontal torsional elastic buffer of the cylindrical elastomer, continuously absorbing kinetic energy, then converting and storing it as elastic potential energy. Finally, the accumulated elastic potential energy is released in a concentrated manner to form impact kinetic energy. The instantaneously released impact kinetic energy is transferred to the lower connector, and then output to the drill bit, completing the horizontal torsional elastic buffer and impact rock-breaking drilling. This drilling tool achieves horizontal torsional elastic buffer and impact rock-breaking drilling, not only improving the drilling speed of the drilling machinery but also protecting the cutting teeth of the drill bit, protecting the drill bit, and extending its service life. However, it cannot obtain rock-breaking parameters and cannot conduct research on the impact rock-breaking mechanism.

[0041] A continuous axial impact rock-breaking hammer generates controllable pressure pulse waves at a high frequency without affecting wellbore trajectory control, enabling high-frequency impact on the drill bit. It connects directly to the drill bit, with the impact force acting directly on the drill bit body; the magnitude of the impact force is adjustable. A PDC drill bit for continuous impact rock breaking via pulse oscillation is also provided. Drilling fluid enters the PDC drill bit and flows out through the water inlet after passing through the pulse sub. A high-speed incident flow is formed through the fluid inlet of the pulse sub, flowing out after passing through the internal flow channel of the pulse sub, creating axial pulse vibrations that act on the drill bit. This impact rock-breaking drill bit utilizes the circulation of drilling fluid within the pulse sub to generate axial pulse vibrations. A hydraulically driven axial vibration impact rock breaker includes an impact mechanism sleeved on a distribution pipe and positioned opposite to the start-up fluid inlet channel. The impact mechanism comprises a start-up pipe and a hydraulically driven hammer tube. The start-up pipe is axially movable and sleeved on the distribution pipe, and the hydraulically driven hammer tube is axially movable and sleeved on the start-up pipe. Driven by the start-up pipe, the hydraulically driven hammer tube impacts the outer body of the hammer. This rock breaker applies axial vibration force to a rotary drilling bit to improve its rock-breaking efficiency and drilling speed. A rock-breaking device and its impact apparatus are also included, featuring a sealing block to prevent soil from entering the placement chamber during impact rock breaking. The sealing block has spiral grooves that connect the outside to the placement chamber, guiding lubricating oil and gas out and preventing pressure buildup in the placement chamber, thus ensuring the reliability of the impact rock breaking. This impact device, along with the aforementioned rock-breaking hammer, PDC drill bit, and rock breaker, are all effective impact rock-breaking devices, but none can obtain rock-breaking parameters, thus hindering research on the impact rock-breaking mechanism.

[0042] In addition, a high-frequency vibration impact rock breaking experimental device was proposed, which uses a drill bit with axial high-frequency vibration and a horizontally rotating rock sample to simulate the high-frequency vibration impact excitation required for rock breaking. This provides an experimental device and method for indoor simulation experiments, enabling the realization of the high-frequency vibration impact rock breaking process. Simultaneously, this experimental device breaks through the existing technology of using a drill bit to break stationary rock samples, opening up a new device and method for high-frequency vibration impact rock breaking. However, it cannot perform torque measurement or study the impact rock breaking mechanism.

[0043] In addition, a test device and experimental method for rock drillability under impact mode can simulate the rock breaking process by drill bit impact mode, providing equipment for rock drillability testing under impact conditions. The experimental method takes into account the brittle characteristics of rock during impact breaking and uses the displacement of a fixed micro drill bit to distinguish the drillability level of different rock samples. It also considers both static and dynamic impact modes of the drill bit. The test results are consistent with actual drilling conditions, but it cannot obtain the cutting force at a certain rotation speed, cannot carry out torque measurement, and also cannot conduct research on the rock breaking mechanism of impact.

[0044] An indoor drilling simulation device and evaluation method under multi-factor environment is used to simulate multi-factor condition parameters affecting drilling, such as rotational speed, drilling pressure, overburden pressure, formation pressure, and bottom hole circulation pressure, under high temperature and high pressure conditions. It evaluates the effects of different drilling fluid treatment agents and drilling fluid systems on drilling speed and bottom hole cleaning effect. However, it does not consider the drilling mode, so it cannot study the rock breaking mechanism related to the drilling mode.

[0045] A testing device and method for rock drillability testing in deep and ultra-deep wells are disclosed. The testing device can simulate the high-pressure environment of the formation at the bottom of the well and test the relationship between drilling depth and time through a displacement sensor at the micro drill bit. It can optimize drilling pressure, rotation speed, drilling fluid type, and predict drilling speed of drilling machinery. It meets the requirements of bottom-hole temperature and pressure during the simulation of deep and ultra-deep well drilling process and has the function of measuring multiple sets of rock drillability values ​​in a single deep borehole experiment. However, it cannot carry out rock breaking tests under impact to explore the impact rock breaking mechanism of deep and ultra-deep wells.

[0046] Next, a rotary adaptive impact drill bit is described. One end of the casing is threaded with an upper connector, and the other end is threaded with a load-bearing body. A central rod is mounted inside the casing via a bushing. A fluid distributor is threaded onto the top of the central rod, and the bottom end of the central rod extends to the outer end of the load-bearing body. A drill bit is threaded onto the end of the central rod extending to the outer end of the load-bearing body. During operation, the counter-torque of the central rod compresses and stores energy in a spring. The drilling fluid creates pressure in the upper connector. Under the combined action of the drilling fluid and the spring, the central rod is accelerated downwards, achieving impact rock breaking. However, this drill bit can only serve as an effective downhole impact rotary tool and is not suitable for indoor impact rotary rock breaking experiments.

[0047] A rock drillability tester under formation conditions includes a clamping mechanism, a pressure balancing mechanism, and a power mechanism. Employing an electromechanical integrated connector, it can simulate temperature, confining pressure, pore pressure, and wellbore mud pressure under formation conditions to conduct realistic and accurate rock drillability tests. It can simulate overburden confining pressure, pore pressure, and wellbore mud pressure up to 90 MPa, providing more practical guidance for drilling operations. While this device simulates the influence of various formation environmental factors on the rock's compressive strength, it cannot freely adjust experimental parameters such as drill bit rotation speed, and therefore cannot conduct indoor impact rock breaking tests at different rotation speeds.

[0048] To address the aforementioned problems, this invention proposes a system and method for predicting the combined rock-breaking effect of rotary-impact drilling. This system, based on preset rotary cutting parameters and preset impact drilling parameters for simulating rotary-impact drilling, utilizes a rotary cutting unit and an impact drilling unit working together to provide the drill bit with rotary cutting torque and vibrational impact excitation for simulation. After the simulation, the rock breaking specific work under rotary-impact drilling conditions is calculated using measured combined rock-breaking parameters, as well as the preset rotary cutting and impact drilling parameters, thereby effectively evaluating the combined rock-breaking effect based on the breaking specific work. This invention applies high-frequency impact vibration to the drill bit through the impact drilling unit, which, under the static pressure of the drill bit, assists the impact rock-breaking action of the rotary cutting unit, effectively improving the rock breaking efficiency. Furthermore, this invention achieves effective evaluation of the rock-breaking effect under combined rock-breaking action, providing a crucial basis for optimizing drilling parameters and for personalized drill bit design and selection. This system can explore the influence of different factors on the rock breaking characteristics under impact load by adjusting arbitrary preset rotary cutting parameters and preset impact drilling parameters. Furthermore, it provides technical means for exploring the rock breaking mechanism of drill bits under combined rotary and impact loads and improving the rock breaking efficiency of drill bits in complex environments, thus laying the foundation for efficient rock breaking by drill bits.

[0049] Example 1

[0050] Figure 1This is a schematic diagram of the overall structure of a system for predicting the combined rock-breaking effect of rotational impact, according to an embodiment of this application. The following refers to... Figure 1 The system for predicting the combined rock-breaking effect of rotational impact described in this invention will be described in detail.

[0051] like Figure 1 As shown, the system for predicting the combined rock-breaking effect of rotary impact drilling includes at least a combined rock-breaking device 11 and a data processing device 12. In this embodiment, the deformation and strength characteristics of the rock in the formation to be predicted are determined using field logging data. Based on the determined characteristics, actual drilling parameters capable of breaking rocks with the current deformation and strength characteristics are configured for the formation to be predicted. These parameters are then used as preset rotary impact drilling parameters (preset rotary cutting parameters and preset impact drilling parameters) to simulate the rotary impact rock-breaking process. The combined rock-breaking device 11 performs rotary impact rock-breaking simulation on the core sample of the formation to be predicted based on the preset rotary cutting parameters and preset impact drilling parameters to obtain the corresponding combined rock-breaking parameters. The combined rock-breaking device 11 includes a rotary cutting unit 111 for providing rotary cutting torque to the drill bit and an impact drilling unit 112 for providing vibration and impact excitation to the drill bit. After rock breaking is completed, the data processing device 12 uses the preset rotary cutting parameters in the composite rock breaking device 11 and the current drilling depth to calculate the rock breaking volume. Based on this, it calculates the specific work of core breaking by combining the composite rock breaking parameters, the rotary shear rock breaking energy generated by rotary cutting and the impact rock breaking energy generated by impact drilling, in order to evaluate the rock breaking effect of the formation to be predicted.

[0052] Next, the various devices in the system for predicting the combined rock-breaking effect of rotational impact described in this invention will be described in detail.

[0053] The composite rock-breaking device 11 performs a combined rotational-impact rock-breaking simulation on the core sample of the formation to be predicted based on preset rotational cutting parameters and preset impact drilling parameters to obtain corresponding composite rock-breaking parameters. The composite rock-breaking device 11 includes a rotational cutting unit 111 for providing rotational cutting torque to the drill bit and an impact drilling unit 112 for providing vibrational-impact excitation to the drill bit. In this embodiment, a core sample of the formation to be predicted is collected and used to perform a combined rotational-impact rock-breaking simulation indoors to determine the rock drill resistance characteristics of the formation under the combined action of rotational-impact. Specifically, the composite rock-breaking device 11 includes a rotational cutting unit 111 and an impact drilling unit 112. The rotational cutting unit 111 and the impact drilling unit 112 work together. While the rotational cutting unit 111 provides rotational cutting torque to the drill bit, the impact drilling unit 112 also provides vibrational-impact excitation to the drill bit to achieve the combined rotational-impact rock-breaking simulation. Before conducting the rotary-impact composite rock breaking simulation, this embodiment first sets corresponding preset rotary cutting parameters and preset impact drilling parameters for the composite rock breaking device 11. Then, the rotary cutting unit 111 operates simultaneously according to the preset rotary cutting parameters, and the impact drilling unit 112 operates according to the preset impact drilling parameters to perform rock breaking operations. Next, after the rotary-impact composite simulation is completed, the corresponding composite rock breaking parameters are obtained, and the rock drill resistance characteristics of the formation to be predicted are determined based on the composite rock breaking parameters to evaluate the rock breaking effect.

[0054] The impact drilling unit 112 includes a vibrator, which applies external excitation to the drill pipe connected to the drill bit according to preset impact drilling parameters, thereby providing vibration and impact excitation to the drill bit. The preset impact drilling parameters include, but are not limited to, impact waveform, impact force, impact amplitude, and impact frequency. Specifically, the impact drilling unit 112 includes a vibrator, which applies high-frequency external excitation to the drill pipe connected to the drill bit according to preset impact drilling parameters (e.g., impact waveform, impact force, impact amplitude, and impact frequency), causing the drill pipe to drive the drill bit in impact drilling, thereby achieving the purpose of providing vibration and impact excitation to the drill bit.

[0055] The impact drilling unit 112 also includes a pressure sensor and a displacement sensor. During the rotary impact composite simulation, the pressure sensor monitors and records the impact force exerted by the drill bit on the rock core in real time, while the displacement sensor monitors and records the drilling depth of the drill bit in real time. In this embodiment, the rock-breaking progress and the stress state of the rock are determined by the data monitored by the pressure sensor and the displacement sensor, realizing real-time monitoring of the rock-breaking state during the rock-breaking process.

[0056] Furthermore, the impact drilling unit 112 also includes: a vibrator bracket for fixing the vibrator to a support plate, thereby ensuring that the vibrator remains in the same position during rock breaking; and a floating plate fixed to the drill pipe and connected to the vibrator to ensure that the drill pipe receives stable external excitation. In this embodiment, the vibrator bracket is used to fix the vibrator to a support plate arranged at a corresponding position. This support plate does not move with the drilling, thereby ensuring that the vibrator remains in the same position during rock breaking. The floating plate is fixed to the drill pipe and connected to the vibrator. The vibrator indirectly transmits high-frequency excitation to the drill pipe by impacting the floating plate, ensuring that the drill pipe receives stable external excitation.

[0057] In this embodiment, the rotary cutting unit 111 includes, but is not limited to, a drill pressure controller, a speed regulator, and a torque sensor. The drill pressure controller applies different drill pressures to the drill bit, and the speed regulator adjusts the cutting speed of the drill bit, thereby enabling this embodiment to simulate rotary-impact composite rock breaking under different rotary cutting parameters. In addition, the torque sensor monitors and records the cutting torque of the drill bit in real time during the rotary-impact composite simulation. The drill pressure controller also monitors and records the drill load pressure in real time during the rotary-impact composite simulation. This embodiment determines the stress state of the drill bit through the data monitored by the drill pressure controller and the torque sensor, achieving real-time monitoring of the drill bit's stress state during the rock breaking process.

[0058] The system for predicting the combined rock-breaking effect of rotational impact as described in this invention further includes a core clamp for holding and fixing the core. The core clamp employs a four-jaw arc-shaped adjusting rod. Specifically, the core clamp is used to hold and fix a core taken from the stratum to be predicted. In this embodiment, the core clamp is also fixed to a corresponding base, thereby effectively ensuring the stability of the core during the simulation of combined rock-breaking of rotational impact. The core clamp employs a four-jaw arc-shaped adjusting rod, which is suitable for holding cores of different specifications, thus making this system suitable for simulating combined rock-breaking of rotational impact using cores of different specifications.

[0059] In this embodiment, the drill bit has several cutting tooth mounting slots. By configuring different numbers of cutting teeth on the drill bit, each cutting tooth is arranged in a designated mounting slot, thereby forming different blade structures on the drill bit. The cutting teeth are PDC blades. The drill bit has built-in cutting tooth mounting slots, which are used to install corresponding PDC blades as cutting teeth on the drill bit. By configuring different numbers of cutting teeth (PDC blades) on the drill bit and installing the current number of cutting teeth (PDC blades) in the corresponding mounting slots according to a designated installation method, a corresponding blade structure is formed on the drill bit, thus giving the drill bit a corresponding cutting tooth structure. In this way, this embodiment, by changing the number of cutting teeth (PDC blades) and installing the cutting teeth in specific positions according to the cutting tooth specifications of the actual rock-breaking drill bit, can obtain a PDC drill bit with the same cutting tooth specifications as the actual rock-breaking drill bit (having a corresponding blade structure). Furthermore, the drill bit and drill rod are connected by threads, which allows this embodiment to freely replace the drill bit with the corresponding drill bit specifications (size specifications, number of mounting slots, etc.) required for actual rock breaking to simulate rock breaking.

[0060] Furthermore, the data processing device 12, after rock breaking is completed, calculates the rock-breaking volume using preset rotary cutting parameters and the current drilling depth. Based on this, it calculates the specific energy of core breaking using composite rock breaking parameters, the rotary shear rock breaking energy generated by rotary cutting, and the impact rock breaking energy generated by impact drilling, to evaluate the rock breaking effect of the formation to be predicted. In practical applications, rotary cutting mainly affects the rock-breaking volume per unit time, while impact mainly affects the drilling depth per unit time. Therefore, after the rotary-impact composite rock breaking simulation is completed, the data processing device 12 calculates the rock-breaking volume per unit time based on the preset rotary cutting parameters for rotary cutting during the rotary-impact composite rock breaking process and the current drilling depth. Then, using the composite rock breaking parameters, the rotary shear rock breaking energy generated by rotary cutting per unit time, and the impact rock breaking energy generated by impact drilling per unit time, it calculates the specific energy of core breaking of the formation to be predicted (i.e., the energy consumed in breaking rock per unit time), and then uses the specific energy of breaking to evaluate the rock breaking effect of the formation to be predicted under the rotary-impact composite action.

[0061] The data processing device 12 includes a rock-breaking volume calculation unit. This unit extracts the number of cutting teeth and the drill bit diameter from preset rotary cutting parameters, and calculates the rock-breaking volume using these parameters and the current drilling depth. In this embodiment, the preset rotary cutting parameters include, but are not limited to, drill bit type data (e.g., drill bit diameter, cutting tooth size, number of cutting teeth) used in the rotary impact composite simulation, as well as the drill bit's cutting speed and the drilling pressure applied to the drill bit. The rock-breaking volume calculation unit extracts the number of cutting teeth and the drill bit diameter from the preset rotary cutting parameters, and calculates the rock-breaking volume per unit time using these parameters and the drilling depth in the rotary impact composite simulation. This allows the unit to obtain the energy consumed in breaking the rock per unit time, determine the current drill resistance characteristics of the formation rock to be predicted, and then evaluate the rock-breaking effect of the formation based on these drill resistance characteristics.

[0062] In this embodiment of the application, the rock-breaking volume is calculated using the following expression:

[0063]

[0064] Where V represents the rock breaking volume, N represents the number of cutting teeth, D represents the drill bit diameter, d represents the cutting tooth diameter, θ represents the cutting tooth back slope angle, h represents the drilling depth, and β represents the cutting tooth side slope angle.

[0065] The data processing device 12 also includes a rotary shear rock-breaking energy calculation unit. This unit extracts drill bit cutting force data from the composite rock-breaking parameters, as well as drill bit diameter and cutting speed from the preset rotary cutting parameters. It then uses the drill bit cutting force data, drill bit diameter, and cutting speed to calculate the rotary shear rock-breaking energy. In this embodiment, the composite rock-breaking parameters include, but are not limited to, drill bit cutting force, impact force of the drill bit on the rock core, drill bit drilling depth, drill bit cutting torque, drill load pressure, and rock cutting mass. The rotary shear rock-breaking energy calculation unit extracts drill bit cutting force data from the composite rock-breaking parameters, as well as drill bit diameter and cutting speed from the preset rotary cutting parameters. It then uses the drill bit cutting force data, drill bit diameter, and cutting speed to calculate the work consumed by the drill bit's rotary cutting and rock-breaking per unit time, and uses this work as the rotary shear rock-breaking energy per unit time in this embodiment.

[0066] In this embodiment, the rotational shear rock-breaking energy is calculated using the following expression:

[0067]

[0068] Among them, W sr This represents the rotational shear rock-breaking energy per unit time, where F represents the drill bit cutting force and n represents the cutting speed.

[0069] Furthermore, the data processing device 12 is also used to obtain the kinetic energy of the rock fragments that convert the core into rock fragments during the rock breaking process using the mass of rock fragments in the composite rock breaking parameters, and to correct the impact rock breaking energy using the kinetic energy of the rock fragments. Based on the corrected impact rock breaking energy, the rock breaking effect of the formation to be predicted is evaluated. Under high strain rate impact rock breaking conditions, the energy absorbed by the core mainly consists of fracture damage energy, rock fragment kinetic energy, and a small amount of thermal energy and acoustic emission energy. Among these, thermal energy and acoustic emission energy are negligible. That is to say, in the rotary impact composite rock breaking simulation process, not all of the total impact energy output by the vibrator is used for impact drilling. Therefore, this embodiment removes the kinetic energy of the rock fragments that convert the core into rock fragments during the rock breaking simulation from the total impact energy output by the vibrator to obtain the energy actually used for impact drilling from the total impact energy output by the vibrator. This corrects the impact rock breaking energy, and then uses the corrected impact rock breaking energy to obtain a more accurate evaluation result of the rock breaking effect of the formation to be predicted.

[0070] In calculating the kinetic energy of the rock fragments, firstly, the data processing device 12 weighs all the rock fragments generated after the composite rock breaking simulation to obtain the mass of the rock fragments in the composite rock breaking parameters. Then, using the mass of the rock fragments in the composite rock breaking parameters, the kinetic energy of the rock fragments is calculated. By removing the kinetic energy of the rock fragments from the total impact energy output by the vibrator, the total impact energy output by the vibrator, which serves as the original impact rock breaking energy, is corrected to the energy actually used for impact drilling. Based on the corrected impact rock breaking energy, the rock breaking effect of the predicted formation is evaluated. The total impact energy output by the vibrator is obtained by multiplying the vibrator output energy per unit time by the drilling time.

[0071] In this embodiment, the kinetic energy of the debris is calculated using the following expression:

[0072]

[0073] Among them, W d denoted by , m represents the kinetic energy of the rock fragments, and m represents the mass of the rock fragments.

[0074] Next, this embodiment, based on the proportion of non-debris kinetic energy in the total impact energy output by the vibrator, and combined with the method of obtaining the total impact energy output by the vibrator, determines the energy actually used for impact drilling per unit time in the vibrator output energy, and uses the energy actually used for impact drilling per unit time as the corrected impact rock-breaking energy, thereby achieving the correction of the impact rock-breaking energy. The impact rock-breaking energy is corrected using the following expression:

[0075]

[0076] Among them, W sk W represents the corrected rock-breaking impact energy per unit time. jz This indicates the total impact energy output by the vibrator.

[0077] Furthermore, the data processing device 12 also includes a rock breaking specific energy calculation unit. This unit calculates the total rock breaking energy during the combined rotary-impact rock breaking process by utilizing the rotary shear rock breaking energy generated by rotary cutting and the impact rock breaking energy generated by impact drilling. Then, it uses the total rock breaking energy and the broken volume to obtain the rock breaking specific energy. Specifically, the unit sums the rotary shear rock breaking energy generated by rotary cutting and the impact rock breaking energy generated by impact drilling per unit time to obtain the total rock breaking energy per unit time. Then, the unit calculates the rock breaking specific energy using the current total rock breaking energy and broken volume per unit time. Based on the rock breaking power consumption characteristics reflected by the rock breaking specific energy, the unit uses the rock breaking specific energy as an evaluation index to assess the combined rotary-impact rock breaking effect, thereby evaluating the rock breaking effect of the formation to be predicted. In this embodiment, the rock breaking specific energy is the power consumption per unit time of the PDC drill bit's combined rotary-impact action on the core, resulting in the breaking of a unit volume of core.

[0078] In this embodiment of the application, the total rock-breaking energy in the rotary impact combined rock-breaking simulation is calculated using the following expression:

[0079] W t =W sr +W s (5)

[0080] Among them, W t It represents the total rock-breaking energy per unit time.

[0081] In this embodiment of the application, the breaking specific work is calculated using the following expression:

[0082]

[0083] Where E represents the specific work of breaking up the rock.

[0084] In one specific embodiment of this application, the rotary impact composite rock breaking system only activates the impact drilling unit 112. At this time, the corrected impact rock breaking energy is taken as the total rock breaking energy per unit time for rock breaking of the formation to be predicted under the action of impact drilling only. Then, using the same prediction method as the prediction of rotary impact composite action, the prediction of the rock breaking effect of the formation to be predicted under the action of impact only is realized.

[0085] Furthermore, this embodiment uses historical fracturing energy data from the actual drilling process to divide the historical fracturing energy data under the same drilling conditions into multiple adjacent numerical intervals based on the magnitude of the fracturing energy. For each interval, a corresponding rock drill resistance evaluation level is assigned (the smaller the fracturing energy, the worse the rock's drill resistance). By utilizing the rock drill resistance evaluation level corresponding to the interval containing the fracturing energy of the current formation to be predicted, the drill resistance characteristics of the formation to be predicted are determined. Then, based on the drill resistance characteristics, the rock-breaking effect of the combined rotational impact on the formation to be predicted is evaluated. Specifically, under the same drilling conditions, the smaller the fracturing energy, the worse the rock's drill resistance, and the better the rock-breaking effect of the current combined rotational rock-breaking action on the formation to be predicted.

[0086] In one specific embodiment of this application, the system of the present invention further includes a main control device. During the simulation of rotary-impact composite rock breaking, the main control device receives real-time data from the drill pressure controller and torque sensor in the rotary cutting unit 111, and the pressure sensor in the impact drilling unit 112. It monitors the real-time operating parameters of the rotary cutting unit 111 and the impact drilling unit 112 to determine whether the real-time operating parameters are consistent with preset rotary cutting parameters and preset impact drilling parameters, thereby determining whether the system is in an abnormal operating state and issuing an alarm for any abnormality. Furthermore, the main control device is equipped with a data storage unit. This data storage unit stores the real-time monitoring data from the drill pressure controller and torque sensor in the rotary cutting unit 111, and the pressure sensor in the impact drilling unit 112, as well as the real-time operating parameters of the rotary cutting unit 111 and the impact drilling unit 112. When relevant personnel or equipment require data access, the relevant data is output. Meanwhile, in this embodiment, the main control device is also pre-set with data processing rules (e.g., table generation rules, image generation rules, etc.) for different types of data stored in the data storage unit. After the data storage unit receives data of the corresponding type, the main control device uses the preset data processing rules to generate a data table or graph for the corresponding type of data. In addition, the main control device is also used to control the rotary cutting unit 111 and the impact drilling unit 112 to operate according to preset rotary cutting parameters and preset impact drilling parameters by issuing corresponding operating instructions to them, thereby realizing automated control of the simulation process of the system used in this embodiment for predicting the combined rotary-impact rock breaking effect.

[0087] Accordingly, this embodiment simulates the rotary-impact combined rock breaking process by fixing rock cores taken from the formation to be predicted in the system's core clamp and configuring actual drilling parameters (preset rotary cutting parameters and preset impact drilling parameters) for the formation to be predicted, based on the deformation and strength characteristics of the rock in the formation determined by field logging data, to break rocks with the current deformation and strength characteristics. Furthermore, based on the simulation results, the rock's drill resistance characteristics under rotary-impact combined action are determined, thereby evaluating the rock breaking effect of the formation under rotary-impact combined action based on the rock's drill resistance characteristics.

[0088] In a specific embodiment of the present invention, firstly, a drill bit with a three-blade structure, having a diameter of 50 mm, a cutting tooth diameter of 13 mm, and a side rotation angle of 15°, is selected and installed on the drill pipe via a threaded connection to form the system described in this embodiment. Next, a core sample taken from the formation to be predicted is fixed in a core clamp, and the core clamp adjustment rod is adjusted according to the current core size to fix the core, thereby completing the preparation work for the rotational impact composite rock breaking simulation of the formation to be predicted. Then, the deformation and strength characteristics of the rock in the current formation to be predicted are determined using field logging data, and the following preset parameters are configured for the rock breaking simulation: a drill pressure of 500 N, a cutting speed of 55 r / min, an impact amplitude of 1.5 mm, an impact frequency of 25 Hz, and an impact force of 200 N.

[0089] In the simulation of rotary-impact composite rock breaking, the drill pipe and drill bit descend in tandem until initial contact with the drill bit core. Then, the rotary cutting unit and impact drilling unit begin drilling according to preset parameters, with a target drilling depth of 50mm. Once the drill bit reaches the target depth, it rises to unload, at which point the rock breaking simulation ends. During drilling, the drill pressure controller and torque sensor in the rotary cutting unit, and the pressure sensor in the impact drilling unit, collect and monitor relevant data in real time. Next, under the current rock breaking simulation conditions, only the impact frequency is adjusted, and another core sample from the same formation to be predicted is used for re-drilling to calculate the corresponding breaking energy. This embodiment compares the breaking energy at different impact frequencies to obtain the influence law of impact frequency on rock breaking effect.

[0090] Example 2

[0091] On the other hand, based on the above-mentioned system for predicting the combined rock-breaking effect of rotational impact, this embodiment of the invention also proposes a method for predicting the combined rock-breaking effect of rotational impact. This method utilizes the above-mentioned system for predicting the combined rock-breaking effect of rotational impact to effectively predict the combined rock-breaking effect of rotational impact. Figure 2This is a step diagram illustrating the method for predicting the combined rock-breaking effect of rotational impact according to an embodiment of this application. Figure 2 As shown, the method for predicting the combined rock-breaking effect of rotary-impact drilling according to the present invention includes the following steps: Step S210: The combined rock-breaking device performs a rotary-impact combined rock-breaking simulation on the core of the formation to be predicted based on preset rotary cutting parameters and preset impact drilling parameters to obtain the corresponding combined rock-breaking parameters. The combined rock-breaking device includes a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit. Step S220: After rock-breaking is completed, the data processing device uses the preset rotary cutting parameters in the combined rock-breaking device in step S210, combined with the current drilling depth, to calculate the rock-breaking volume. Based on this, combined with the combined rock-breaking parameters, the rotary shear rock-breaking energy generated by rotary cutting and the impact rock-breaking energy generated by impact drilling, the specific work of the core is calculated to evaluate the rock-breaking effect of the formation to be predicted.

[0092] This invention proposes a system and method for predicting the effect of rotary-impact combined rock breaking. The system is based on preset rotary cutting parameters and preset impact drilling parameters for simulating rotary-impact combined rock breaking. It utilizes a rotary cutting unit and an impact drilling unit working together to provide the drill bit with rotary cutting torque and vibration impact excitation for simulation. After the simulation, the rock breaking specific work under rotary-impact combined rock breaking conditions is calculated using measured combined rock breaking parameters, as well as the preset rotary cutting and impact drilling parameters. This allows for effective evaluation of the combined rock breaking effect based on the breaking specific work. This invention can simulate the rotary cutting and impact drilling parameters during rotary-impact combined drilling, enabling indoor testing of the rock breaking effect under rotary-impact combined rock breaking. Furthermore, based on measured combined rock breaking parameters, it calculates the rotary shear rock breaking energy and the rotary-impact combined rock breaking energy. Furthermore, this invention utilizes rock-breaking parameters related to rotary cutting during the rotary-impact composite rock-breaking process to calculate the corresponding rock-breaking volume, thereby obtaining the rock fragmentation specific work under the rotary-impact composite rock-breaking method. This allows for normalized energy classification, achieving an effective evaluation of the rock's drill resistance characteristics under composite rock-breaking action, and providing a crucial basis for optimizing drilling parameters and customizing drill bit design and selection. In addition, this invention provides effective testing and evaluation methods for revealing the influence of rotary cutting rock-breaking and rotary-impact composite rock-breaking on drilling speed, and for establishing a method for characterizing rock drill resistance under composite rock-breaking methods.

[0093] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0094] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0095] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0096] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A system for predicting the combined rock-breaking effect of rotational impact, characterized in that, include: A composite rock breaking device is used to simulate the combined rock breaking of the rock core of the formation to be predicted based on preset rotary cutting parameters and preset impact drilling parameters, so as to obtain the corresponding composite rock breaking parameters. The composite rock breaking device includes a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit. A data processing device is used to calculate the rock-breaking volume after rock breaking is completed, using the preset rotary cutting parameters and the current drilling depth. Based on this, and combining the composite rock-breaking parameters, the rotary shear rock-breaking energy generated by rotary cutting, and the impact rock-breaking energy generated by impact drilling, the device calculates the specific work of the rock core to evaluate the rock-breaking effect of the formation to be predicted. Specifically, the device uses the mass of rock fragments in the composite rock-breaking parameters to obtain the kinetic energy of the rock fragments that convert the rock core into rock fragments during the rock-breaking process, and uses this kinetic energy to correct the impact rock-breaking energy. Based on the corrected impact rock-breaking energy, the device evaluates the rock-breaking effect of the formation to be predicted. The data processing device includes a rock-breaking volume calculation unit, which extracts the number of cutting teeth and the drill bit diameter from the preset rotary cutting parameters, and calculates the rock-breaking volume using the number of cutting teeth, the drill bit diameter, and the current drilling depth. The rock-breaking volume is calculated using the following expression: in, V Indicates the volume of broken rock. N This indicates the number of teeth on the cutting gear. D Indicates the drill bit diameter. d Indicates the diameter of the cutting teeth. θ Indicates the back rake angle of the cutting teeth. h Indicates the drilling depth. β This indicates the rake angle of the cutting teeth.

2. The system according to claim 1, characterized in that, The impact drilling unit includes a vibrator, which is used to apply external excitation to the drill rod connected to the drill bit according to the preset impact drilling parameters, thereby providing vibration impact excitation to the drill bit. The preset impact drilling parameters include, but are not limited to, impact waveform, impact force, impact amplitude and impact frequency.

3. The system according to claim 2, characterized in that, The impact drilling unit also features: A vibrator bracket for fixing the vibrator to a support plate, thereby ensuring that the vibrator remains in the same position throughout the rock-breaking process; and A floating plate, which is fixed to the drill pipe and connected to the vibrator, is used to ensure that the drill pipe receives stable external excitation.

4. The system according to any one of claims 1 to 3, characterized in that, The system also includes: A core clamp is used to hold and fix the core. The core clamp adopts a four-jaw arc-shaped adjusting rod. The drill bit has several cutting tooth mounting slots. By configuring different numbers of cutting teeth on the drill bit, each cutting tooth is arranged in a designated mounting slot, thereby forming different blade structures on the drill bit. The cutting teeth are PDC blades.

5. The system according to any one of claims 1 to 4, characterized in that, The data processing device further includes: The rotary shear rock-breaking energy calculation unit is used to extract the drill bit cutting force data from the composite rock-breaking parameters, and the drill bit diameter and cutting speed from the preset rotary cutting parameters. It then uses the drill bit cutting force data, the drill bit diameter, and the cutting speed to calculate the rotary shear rock-breaking energy, wherein the rotary shear rock-breaking energy is calculated using the following expression: in, W sr This represents the rotational shear energy used to break rocks per unit time. F This indicates the cutting force of the drill bit. D Indicates the drill bit diameter. n This indicates the cutting speed.

6. The system according to claim 1, characterized in that, The kinetic energy of the debris is calculated using the following expression: in, W d Represents the kinetic energy of debris. n Indicates the cutting speed. m Indicates the mass of rock fragments. D Indicates the drill bit diameter.

7. The system according to any one of claims 1 to 6, characterized in that, The data processing device further includes: The rock-breaking specific energy calculation unit is used to obtain the total rock-breaking energy in the combined rotary-impact rock-breaking process by utilizing the rotary shear rock-breaking energy generated by rotary cutting and the impact rock-breaking energy generated by impact drilling. Then, it uses the total rock-breaking energy and the rock-breaking volume to obtain the rock-breaking specific energy, wherein the rock-breaking specific energy is calculated using the following expression: in, E Indicates the ratio of broken to work. W t This represents the total rock-breaking energy. V Indicates the volume of broken rock.

8. A method for predicting the combined rock-breaking effect of rotational impact, characterized in that, The method is implemented using the system as described in any one of claims 1 to 7, wherein the method comprises: The composite rock breaking device simulates the combined rock breaking of the rock core of the formation to be predicted based on preset rotary cutting parameters and preset impact drilling parameters, so as to obtain the corresponding composite rock breaking parameters. The composite rock breaking device includes a rotary cutting unit for providing rotary cutting torque to the drill bit and an impact drilling unit for providing vibration and impact excitation to the drill bit. After rock breaking is completed, the data processing device uses the preset rotary cutting parameters and the current drilling depth to calculate the rock breaking volume. Based on this, and combining the composite rock breaking parameters, the rotary shear rock breaking energy generated by rotary cutting, and the impact rock breaking energy generated by impact drilling, the core fragmentation specific work is calculated to evaluate the rock breaking effect of the formation to be predicted. Specifically, the mass of rock fragments in the composite rock breaking parameters is used to obtain the kinetic energy of the rock fragments that convert the core into rock fragments during the rock breaking process. This kinetic energy is then used to correct the impact rock breaking energy, thereby evaluating the rock breaking effect of the formation to be predicted based on the corrected impact rock breaking energy. The data processing device includes a rock breaking volume calculation unit, which extracts the number of cutting teeth and the drill bit diameter from the preset rotary cutting parameters, and calculates the rock breaking volume using the number of cutting teeth, the drill bit diameter, and the current drilling depth. The rock breaking volume is calculated using the following expression: in, V Indicates the volume of broken rock. N This indicates the number of teeth on the cutting gear. D Indicates the drill bit diameter. d Indicates the diameter of the cutting teeth. θ Indicates the back rake angle of the cutting teeth. h Indicates the drilling depth. β This indicates the rake angle of the cutting teeth.

Images