Horizontal well drilling PDC drill bit surface balling drum generation-release simulation device and method

Abstract

The invention relates to a horizontal well drilling PDC drill bit surface mud drum generation-removal simulation device and method. An experiment platform comprises a simulation horizontal shaft, a simulation drill column, a simulation PDC drill bit, a simulation mud shale fixing device, a drilling scale, a data acquisition device, a camera device, a three-dimensional scanning measuring instrument and a constant temperature control device. The simulation drill column is connected with the simulation PDC drill bit; the simulation drill column is driven by the driving device; the data acquisition device acquires operation and experiment image data of the driving device; the three-dimensional scanning measuring instrument is used for collecting the rock debris adhesion condition of the surface of the simulated PDC drill bit and the cross section condition of the drilled simulated shale; and the constant temperature control device is used for controlling the temperature in the simulated shale fixing device. The device provided by the invention is reliable in working performance, good in simulation effect, simple in experimental operation and reasonable in design, and the adhesion change condition of the argillaceous rock debris on the surface of the drill bit in the rotary drilling process can be visually observed.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, and in particular to a simulation experimental platform and method for horizontal well PDC drill bit generation and release, shale rock breaking and annular particle migration. Background Art

[0002] According to statistics, in oil production, about 60%-80% of the drilled formations are mud shale formations. With the improvement of PDC production technology and the advancement of PDC drill bit design and manufacturing technology, its application is becoming more and more extensive. When the PDC drill bit is drilling into the mud shale formation in the environment of water-based drilling fluid, due to the high clay mineral content of the formation (about 30%-60%), the muddy rock cuttings are easily hydrated and expanded and have viscosity, which is very easy to adhere to the PDC cutting teeth and the surface of the drill bit, and frequently cause the drill bit to be mud-packed. When the PDC drill bit is mud-packed, the drill bit cannot effectively break the rock, the drilling speed slows down, the water hole is blocked, and a high pump pressure is formed, and even the pump is blocked. In the case of ineffective treatment, the drill can only be manually cleared by pulling out the drill, resulting in unnecessary pulling out and drilling, thereby increasing the drilling cost; at the same time, the drilling time utilization rate is low, which prolongs the drilling cycle. For this reason, a systematic analysis of the PDC drill bit mud packing phenomenon is made to find out the influencing factors of the PDC drill bit mud packing, and at the same time formulate corresponding countermeasures, which plays a very important role in guiding on-site production. Therefore, it is necessary to build an experimental platform for the formation and removal of mud bags and analyze the solutions in detail.

[0003] The existing equipment can carry out indoor simulation of horizontal well drilling, static evaluation of mud bag formation around PDC drill bits, drilling fluid circulation or cuttings migration in horizontal wells, and an experimental platform for the formation and removal of mud bags on the surface of PDC drill bits during rotary drilling. External power is applied, and most of the experiments are based on vertical wells. The existing equipment focuses on the basic components of horizontal well drilling equipment, analyzes the interaction between the drill string and the well wall, the influence of drilling fluid on the lubrication of the well wall or pipe string, and the carrying of cuttings. The power system used is driven by an external motor in the wellbore, not the actual process of horizontal well drilling, such as the pipe, drilling fluid immersion, and near-bit rotary drive. At the same time, less attention is paid to the situation of cuttings on the surface of PDC drill bits (especially soft mudstone adhesion). There is no quantitative evaluation experimental device for the formation and removal of mud bags on the surface of PDC drill bits during horizontal well drilling. At present, the drilling and application of horizontal wells are gradually increasing, and the research on the formation and removal mechanism of mud bags on the surface of horizontal well PDC drill bits needs to be analyzed, especially the analysis of mud bags on the surface of drill bits under the conditions of downhole rotary drive in simulated horizontal well drilling. At the same time, the drilling process of submarine hydrate reservoirs needs to consider the mud balling problem in the soft mudstone layer. It is necessary to build a mud balling-removal experimental platform and analyze the mechanism of horizontal well PDC drill bits under different temperature environments, which can provide a basis for the optimization design of process parameters for preventing and controlling mud balling on the drill bit surface. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned background technology, the present invention proposes a simulation device for mud bag formation and removal on the surface of PDC drill bit for horizontal well drilling. The device has reliable working performance, good simulation effect, simple experimental operation and reasonable design, and can visually observe the changes in muddy rock cuttings adhesion on the drill bit surface during rotary drilling.

[0005] The technical solution of the present invention to solve the above problems is:

[0006] A device for simulating the formation and removal of mud packing on the surface of a PDC drill bit for horizontal well drilling, which is special in that:

[0007] It includes a simulated horizontal wellbore, a simulated drill string, a simulated PDC drill bit, a simulated shale fixture, a drilling ruler, a data acquisition device, a camera device, a three-dimensional scanning measuring instrument and a constant temperature control device.

[0008] One end of the simulated horizontal wellbore is detachably connected to the simulated shale fixture, one end of the simulated horizontal wellbore is provided with a drainage port, the simulated drill string is connected to the simulated PDC drill bit, the simulated drill string is provided with a driving device, and the driving device is connected to the cable outside the pipe; the simulated drill string is driven by the driving device, and the drilling scale is installed on the surface of or directly below the simulated horizontal wellbore and is placed horizontally; the data acquisition device is connected to the cable outside the pipe and the camera device to collect the operation data of the driving device and the experimental image data; the three-dimensional scanning measuring instrument is used to collect the cuttings adhesion condition on the surface of the simulated PDC drill bit and the cross-section condition of the drilled simulated shale; the constant temperature control device is used to control the temperature inside the simulated shale fixture.

[0009] Furthermore, the simulated drill string is equipped with a first centralizer, a second centralizer and a universal shaft.

[0010] Furthermore, the above-mentioned driving device includes a waterproof driving motor or a turbine driving rotor; the simulated PDC drill bit is electrically driven by the waterproof driving motor, and the universal joint, the waterproof driving motor and the simulated PDC drill bit are connected with a bypass fluid infusion pipe, or the simulated PDC drill bit is hydraulically driven by the turbine driving rotor.

[0011] Furthermore, the above-mentioned simulated shale fixing device includes a cylindrical body and a second internal threaded plug, and the two ends of the cylindrical body are respectively provided with a first internal threaded joint and a second external threaded joint; one end of the simulated horizontal wellbore is provided with a first external threaded joint; the first external threaded joint and the first internal threaded joint are connected by a circular thread, and the second external threaded joint and the second internal threaded plug are connected by a circular thread, and the cylindrical body is used to fill simulated shale.

[0012] Furthermore, the simulated horizontal wellbore is a transparent tube, which is convenient for obtaining experimental image data, cuttings adhesion conditions, and cross-sectional conditions of the drilled simulated shale; and the simulated drill string is elastic.

[0013] Furthermore, the above-mentioned horizontal well drilling PDC drill bit surface mud bag generation and removal simulation device also includes a horizontal well drilling rig; the horizontal well drilling rig includes a straight well section straightener, a pressurized infusion connector, an input pipe, an input pump, a simulated fresh mud pool, an agitator, an output pipe, a simulated return liquid pool, a second drilling ruler, an overflow prevention pipe, and a wellbore fixing device.

[0014] The wellbore fixing device is used to fix the simulated horizontal wellbore. The simulated drill string is connected to the vertical well section straightener and the pressurized infusion joint. The simulated drilling fluid enters the input pipe and the pressurized infusion joint from the simulated fresh mud pool through the input pump. The agitator is placed in the simulated fresh mud pool. The returned simulated drilling fluid enters the output pipe and the simulated return fluid pool through the simulated PDC drill bit, the annulus between the simulated drill string and the simulated horizontal wellbore, and the overflow prevention pipe; the simulated drill string is sealed and connected to the overflow prevention pipe, and a second drilling ruler is vertically arranged on the outside of the overflow prevention pipe to measure the drilling distance of the simulated drill string.

[0015] Furthermore, the outer side of the simulated PDC drill bit is provided with a plurality of chip grooves, blades and nozzles.

[0016] Furthermore, the simulated PDC drill bit is made of resin or metal, and marks are set on the surface of the simulated PDC drill bit according to symmetry.

[0017] In addition, the present invention also proposes a horizontal well rotary drilling PDC drill bit mud ball generation-removal simulation experimental method, which is special in that it is based on the above-mentioned horizontal well drilling PDC drill bit surface mud ball generation-removal simulation device, including the following steps:

[0018] Step 1: Preparation and device construction. The experimental process is as follows:

[0019] S01 Preparation: Prepare simulated shale and simulated drilling fluid;

[0020] S02 builds a simulation device for the formation and removal of mud bags on the surface of PDC drill bits for horizontal well drilling;

[0021] S03 sealing test.

[0022] Step 2: Drilling simulation experiment, the experimental process is as follows:

[0023] S01 contact with simulated shale: push the simulated drill string to make the simulated PDC drill bit close to the top of the simulated shale;

[0024] S02 Drilling: Turn on the input pump, use the waterproof drive motor or turbine drive rotor to drive the simulated PDC drill bit to rotate, push the simulated drill string at a certain drilling speed, and simulate the PDC drill bit to drill the simulated shale. The drilling distance can be controlled by the propulsion of the simulated drill string and read by the drilling ruler and the second drilling ruler; stop drilling when a certain drilling distance or drilling time is reached, turn off the input pump and the waterproof drive motor, and discharge the simulated drilling fluid from the drainage port;

[0025] S03 Phenomenon observation: simulate the drilling of PDC drill bit in mud shale, which can be captured by 3D scanning measuring instrument and camera device, and recorded in data acquisition device, and the drilling process of simulated PDC drill bit in different positions can be followed up in real time through the slide of 3D scanning measuring instrument; open the first external thread joint, the first internal thread joint, the second external thread joint, and the second internal thread plug, measure the accumulation of muddy rock cuttings on the surface of simulated PDC drill bit and the shape of the top of simulated mud shale;

[0026] S04 Parameter sensitivity analysis: The waterproof drive motor and turbine drive rotor control the rotation speed, and observe the drilling condition, wear condition, surface cuttings adhesion, and cuttings accumulation of the simulated PDC drill bit at different rotation speeds; the simulated drill string and drilling ruler, pressurized infusion connector and second drilling ruler can mark the drilling distance, and observe the wear condition, surface cuttings adhesion, and cuttings accumulation of the simulated PDC drill bit at different drilling distances; the input pump adjusts the simulated drilling flow and pumping mode; the simulated PDC drill bit opens or closes one or more nozzles on the surface to analyze the influence of nozzle jet on surface cuttings adhesion, PDC drill bit drilling, and cuttings accumulation.

[0027] Step 3: Mud bag removal experiment, the experimental process is as follows:

[0028] S01 device startup: connect the second internal thread plug to the first external thread joint, use the original simulated drilling fluid or configure the mud pack removal drilling fluid, turn on the input pump to control the flow of the simulated drilling fluid, control the rotation speed of the simulated PDC drill bit, and flush the mud pack on the surface of the simulated PDC drill bit and the rock cuttings accumulated at the bottom of the well;

[0029] S02 Phenomenon observation: The phenomenon is captured by a three-dimensional scanning measuring instrument and a camera device and recorded in a data acquisition device; the first external thread joint and the second internal thread plug are opened to measure the accumulation of muddy rock cuttings on the surface of the simulated PDC drill bit.

[0030] Step 4: Data analysis and result summary:

[0031] The analysis was conducted based on the experimental data, including the drilling conditions of the drill bit, the formation of mud balls, and the removal of mud balls. The effects of different parameters (including mud type and ratio, simulated drilling fluid flow, drilling distance, drilling speed, simulated PDC drill bit shape and surface pretreatment, etc.) on the formation and removal of mud balls were analyzed.

[0032] Furthermore, in the above step one, S02 builds a horizontal well drilling PDC drill bit surface mud bag generation-removal simulation device specifically by: respectively connecting the various components of the simulated horizontal wellbore, simulated drill string, and horizontal well drilling rig; the simulated PDC drill bit is close in proportion to the existing PDC drill bit, and the parameters of the chip groove, nozzle, blade, and tooth components are designed, and a water eye flow sensor, a water eye flow pulse regulator, and a control short section can be installed; the simulated horizontal wellbore is fixed by a wellbore fixing device, and the simulated drill string is installed into the simulated horizontal wellbore.

[0033] The S03 sealing test specifically includes: injecting water into the device through an input pump to ensure that there is no leakage, and discharging the water from the drain port; turning on the constant temperature control device to simulate the temperature of drilling into the formation; loading the simulated shale into the simulated horizontal wellbore from the second internal threaded plug, and reconnecting the simulated horizontal wellbore; simulating the PDC drill bit to work without rotation and at a certain distance from the simulated shale, and slowly injecting simulated drilling fluid through the input pump.

[0034] Advantages of the present invention:

[0035] 1) The present invention can adjust the temperature, injection pressure, simulate rock types, realize horizontal well drilling simulation under different formation conditions, and realize the simulation analysis of the mechanism of mud bag formation and release during the drilling process of horizontal well PDC drill bits in high-temperature and low-temperature formations such as shale and submarine soft mud layers;

[0036] 2) The present invention can realize the influence of different parameters (including mud type and ratio, simulated drilling fluid flow, drilling distance, drilling speed, simulated PDC drill bit shape, etc.) on the formation and removal of mud balls, and visually analyze the drilling condition, wear condition, surface cuttings adhesion, and cuttings accumulation of PDC drill bits;

[0037] 3) The experimental equipment of the present invention is mainly focused on the quantitative analysis and monitoring of horizontal well section drilling. When the drill bit position is changed, such as the vertical well section or the deflection section, the surface mud balling of the PDC drill bit and the change of drilling parameters in the vertical well section or the deflection section can also be evaluated;

[0038] 4) The experimental equipment is simple and convenient to operate, and the cost is low;

[0039] 5) The present invention provides more favorable research conditions for the generation and release of a PDC drill bit for a horizontal well (as well as shale rock breaking and annular particle migration and accumulation), which is conducive to further understanding the mechanism of mud ball generation and release during the drilling process of the simulated drill bit under shale, and can also provide a basis for the optimization design of process parameters for preventing and controlling mud balling on the drill bit surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of a horizontal well section of a PDC drill bit surface balling generation-removal simulation device for horizontal well drilling proposed by the present invention;

[0041] Figure 2 Schematic diagram of a horizontal well drilling rig (vertical well section and other auxiliary parts) of a simulation device for forming and removing mud balls on the surface of a PDC drill bit for horizontal well drilling;

[0042] Figure 3 Schematic diagram of the points for quantitative characterization of mud packing on the surface of PDC drill bits.

[0043] Description of reference numerals:

[0044] 1-simulated horizontal wellbore; 2-first centralizer; 3-simulated drill string; 4-second centralizer; 5-universal shaft; 6-waterproof drive motor; 7-external cable; 8-turbine drive rotor; 9-bypass infusion pipe; 10-simulated PDC drill bit; 11-first external thread joint; 12-first internal thread joint; 13-simulated shale; 14-second external thread joint; 15-second internal thread plug; 16-drilling scale; 17-data acquisition device; 18-camera device; 19-3D scanning measuring instrument; 20-constant temperature control device; 21-drain port; 22-vertical well section centralizer; 23-pressurized infusion joint; 24-input pipe; 25-input pump; 26-simulated fresh mud pool; 27-mixer; 28-output pipe; 29-simulated return liquid pool; 30-second drilling scale; 31-overflow prevention pipe; 32-wellbore fixing device. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0046] See also Figure 1 The present invention proposes a device for simulating the formation and removal of mud bags on the surface of a PDC drill bit for horizontal well drilling, comprising a simulated horizontal wellbore 1, a simulated drill string 3, a simulated PDC drill bit 10, a simulated mud shale fixing device, a drilling ruler 16, a data acquisition device 17, a camera device 18, a three-dimensional scanning measuring instrument 19 and a constant temperature control device 20.

[0047] One end of the simulated horizontal wellbore 1 is detachably connected to the simulated shale fixing device, a drainage port 21 is set at one end of the simulated horizontal wellbore 1, the simulated drill string 3 is connected to the simulated PDC drill bit 10, and a driving device is set on the simulated drill string 3, and the driving device is connected to the external cable 7; the simulated drill string 3 is driven by the driving device, and the drilling scale 16 is installed on the surface of the simulated horizontal wellbore 1 or just below it and is placed horizontally; the data acquisition device 17 is connected to the external cable 7 and the camera device 18 to collect the operation and experimental image data of the driving device; the three-dimensional scanning measuring instrument 19 is installed on the outside of the simulated horizontal wellbore 1, and the three-dimensional scanning measuring instrument 19 is used to collect the rock cuttings adhesion on the surface of the simulated PDC drill bit and the cross-section of the drilled simulated shale 13; the constant temperature control device 20 is installed on the outer surface of the simulated horizontal wellbore 1, and the constant temperature control device 20 is used to control the temperature in the simulated shale fixing device; the drainage port 21 is installed at the inlet end of the simulated horizontal wellbore 1.

[0048] Specifically, see Figure 1 The simulated drill string 3 is equipped with a first stabilizer 2, a second stabilizer 4 and a universal shaft 5. The driving device includes a waterproof driving motor 6 or a turbine driving rotor 8; the simulated PDC drill bit 10 is electrically driven by the waterproof driving motor 6, and the universal shaft 5, the waterproof driving motor 6 and the simulated PDC drill bit 10 are connected with a bypass fluid infusion pipe 9, or the simulated PDC drill bit 10 is hydraulically driven by the turbine driving rotor 8. The micro motor does not support an internal fluid flow channel, and through the bypass fluid infusion pipe 9, the simulated drilling fluid can bypass the waterproof driving motor 6 and enter the simulated PDC drill bit 10.

[0049] The size of the first centralizer 2, the second centralizer 4, the universal shaft 5, and the simulated PDC drill bit 10 (outer diameter 32mm) is similar to the inner diameter (35mm) of the simulated horizontal wellbore 1, so as to realize the simulated drill string centering drilling; the universal shaft 5, the waterproof drive motor 6, the outer cable 7, and the turbine drive rotor 8 simulate the downhole drive, and the speed of the waterproof drive motor 6 is adjustable, between 10-300r / min, the power is 15W, and the current is 1.3A. The number of centralizers is not limited to two, but can be one or more. When multiple centralizers are used, the simulated drill string can be better guaranteed to be centered.

[0050] In this embodiment, see Figure 1The simulated mud shale fixing device comprises a cylindrical body and a second internal thread plug 15, and the two ends of the cylindrical body are respectively provided with a first internal thread joint 12 and a second external thread joint 14. A first external thread joint 11 is provided at one end of the simulated horizontal wellbore 1; the first external thread joint 11 and the first internal thread joint 12 are connected by round threads, and the second external thread joint 14 and the second internal thread plug 15 are connected by round threads, and the cylindrical body is used to fill simulated mud shale 13.

[0051] In this embodiment, the simulated horizontal wellbore 1 is a transparent tube; the simulated drill string 3 is elastic. Specifically, the simulated horizontal wellbore 1 can be a transparent acrylic tube; the simulated drill string 3 is a rubber tube with a certain elasticity.

[0052] As a preferred embodiment of the present invention, see Figure 2 The horizontal well drilling PDC drill bit surface mud bag generation-removal simulation device also includes a horizontal well drilling rig, which includes a vertical well section straightener 22, a pressurized infusion connector 23, an input pipe 24, an input pump 25, a simulated fresh mud pool 26, an agitator 27, an output pipe 28, a simulated return liquid pool 29, a second drilling ruler 30, an overflow prevention pipe 31, and a wellbore fixing device 32.

[0053] The wellbore fixing device 32 is used to fix the simulated horizontal wellbore 1, the simulated drill string 3 is connected to the vertical well section straightener 22 and the pressurized infusion connector 23, the simulated drilling fluid enters the input pipe 24 and the pressurized infusion connector 23 from the simulated fresh mud pool 26 through the input pump 25, the agitator 27 is placed in the simulated fresh mud pool 26, and the returned simulated drilling fluid enters the output pipe 28 and the simulated return fluid pool 29 through the simulated PDC drill bit 10, the annulus between the simulated drill string 3 and the simulated horizontal wellbore, and the overflow prevention pipe 31; the simulated drill string 3 is sealed and connected to the overflow prevention pipe 31, and a second drilling ruler 30 is vertically arranged on the outside of the overflow prevention pipe 31 for measuring the drilling distance of the simulated drill string 3.

[0054] In this embodiment, the thread sizes of the first external threaded joint 11 and the second external threaded joint 14 are consistent, and the thread sizes of the first internal threaded joint 12 and the second internal threaded plug 15 are consistent.

[0055] In this embodiment, see Figure 3 The simulated PDC drill bit has 6 chip grooves, blades, and nozzles, which can be made of resin or stainless steel and can be replaced by other types of drill bits or hybrid drill bits. The surface of the simulated PDC drill bit is quantitatively marked (7 places each) at different positions of the two chip grooves according to symmetry.

[0056] The present invention also provides a horizontal well rotary drilling PDC drill bit mud ball generation-removal simulation experimental method, according to the horizontal well drilling PDC drill bit surface mud ball generation-removal simulation device, comprising the following steps:

[0057] Step 1: Preparation and device construction. The experimental process is as follows:

[0058] S01 Preparation: Prepare simulated shale 13 and simulated drilling fluid (5% KCl solution is used in this embodiment).

[0059] S02 builds the device: connects the various components of the simulated horizontal wellbore 1, the simulated drill string 3, and the horizontal well drilling rig respectively; the simulated PDC drill bit is close in proportion to the existing PDC drill bit, and the parameters of the chip groove, nozzle, blade, teeth and other components are designed, and the water eye flow sensor, water eye flow pulse regulator and control short section can be installed; the simulated horizontal wellbore 1 is fixed by the wellbore fixing device 32, and the simulated drill string 3 is installed into the simulated horizontal wellbore 1.

[0060] S03 sealing test: water is injected into the device by the input pump 25 for 4 hours to ensure that there is no leakage, and the water is discharged from the drain port 21; the constant temperature control device 20 is turned on to simulate the temperature of the drilling formation (4°C-60°C); the simulated shale 13 (purple-red shale taken from Shangshihezi and gray-black shale of Benxi Formation, 80% of 40-80 mesh particles and 20% of 2mm particles after crushing, with a water content of 20%) is loaded into the simulated horizontal wellbore 1 from the second internal threaded plug 15, and the simulated horizontal wellbore 1 is reconnected; the simulated PDC drill bit is not rotated and is at a certain distance (not less than 5cm) from the simulated shale 13, and the simulated drilling fluid (flow rate is about 10ml / min) is slowly injected by the input pump 24.

[0061] Step 2: Drilling simulation experiment, the experimental process is as follows:

[0062] S01 contacting the simulated mud shale 13: pushing the simulated drill string 3 to make the simulated PDC drill bit 10 approach the top of the simulated mud shale 13;

[0063] S02 Drilling: Turn on the input pump 25 (flow rate 300ml / min), use the waterproof drive motor 6 or the turbine drive rotor 8 to drive the simulated PDC drill bit 10 to rotate (200r / min), push the simulated drill string 3 at a certain drilling speed (1cm / min), and the simulated PDC drill bit 10 drills the simulated shale 13. The drilling distance can be controlled by the propulsion of the simulated drill string 3 and read by the drilling ruler 16 and the second drilling ruler 30; when a certain drilling distance or drilling time is reached (10cm in this embodiment), stop drilling, turn off the input pump 25 and the waterproof drive motor 6, and discharge the simulated drilling fluid from the drain port 21;

[0064] S03 Phenomenon observation: The drilling situation of the simulated PDC drill bit 10 in the mud shale can be captured by the three-dimensional scanning measuring instrument 19 and the camera device 18, and the data acquisition device 17 is recorded. The drilling process of the simulated PDC drill bit 10 at different positions is followed up in real time through the slideway of the three-dimensional scanning measuring instrument 19; the first external thread joint 11, the first internal thread joint 12, the second external thread joint 14, and the second internal thread plug 15 are opened to measure the accumulation of muddy rock cuttings on the surface of the simulated PDC drill bit 10 and the shape of the top of the simulated mud shale. In this embodiment, the surface of the simulated PDC drill bit 10 is marked and partitioned, and the thickness of the muddy rock cuttings on the surface of the simulated PDC drill bit 10 is read using a vernier caliper to quantitatively characterize the degree of mud packing at different positions on the drill bit surface. It is found that the mud pack is most likely to form and has a larger thickness on the side close to the blade teeth (first at B⑤ and B⑥ positions, followed by A⑤ and A⑥ positions), and the mud pack thickness is smaller on the concave side of the blade (A③ and B③ positions).

[0065] S04 Parameter sensitivity analysis: The waterproof drive motor 6 and the turbine drive rotor 8 control the rotation speed, and observe the drilling condition, wear condition, surface rock cuttings adhesion, and rock cuttings accumulation of the simulated PDC drill bit 10 at different rotation speeds; the simulated drill string 3 and the drilling ruler 16, the pressurized infusion connector 23, and the second drilling ruler 30 can mark the drilling distance, and observe the wear condition, surface rock cuttings adhesion, and rock cuttings accumulation of the simulated PDC drill bit 10 at different drilling distances; the input pump 25 adjusts the simulated drilling flow and pumping mode; the simulated PDC drill bit 10 analyzes the influence of the nozzle jet on the surface rock cuttings adhesion, PDC drill bit drilling, and rock cuttings accumulation by opening or closing one or more nozzles on the surface.

[0066] Step 3: Mud bag removal experiment, the experimental process is as follows:

[0067] S01 device startup: connect the second internal thread plug 15 to the first external thread connector 11, use the original simulated drilling fluid or configure the mud pack removal drilling fluid, turn on the input pump 25 to control the flow rate of the simulated drilling fluid, control the rotation speed of the simulated PDC drill bit 10, and flush the mud pack on the surface of the simulated PDC drill bit 10 and the rock cuttings accumulated at the bottom of the well.

[0068] S02 Phenomenon observation: The phenomenon is captured by the three-dimensional scanning measuring instrument 19 and the camera device 18 and recorded in the data acquisition device 17; the first external thread joint 11 and the second internal thread plug 15 are opened to measure the accumulation of muddy rock cuttings on the surface of the simulated PDC drill bit 10.

[0069] Step 4: Data analysis and result summary:

[0070] The analysis was conducted based on the experimental data, including the drilling conditions of the drill bit, the formation of mud balls, and the removal of mud balls; the influence of different parameters (including mud type and ratio, simulated drilling fluid flow, drilling distance, drilling speed, simulated PDC drill bit shape and surface pretreatment, etc.) on the formation and removal of mud balls was analyzed.

[0071] Matters not covered by the present invention are known technologies.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A simulation device for the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling, which is special in that: It comprises a simulated horizontal wellbore (1), a simulated drill string (3), a simulated PDC drill bit (10), a simulated shale (13) fixing device, a drilling ruler (16), a data acquisition device (17), a camera device (18), a three-dimensional scanning measuring instrument (19) and a constant temperature control device (20); One end of the simulated horizontal wellbore (1) is detachably connected to a simulated shale (13) fixing device, a drainage port (21) is provided at one end of the simulated horizontal wellbore (1), the simulated drill string (3) is connected to a simulated PDC drill bit (10), a driving device is provided on the simulated drill string (3), and the driving device is connected to an external cable (7); The simulated drill string (3) is driven by a driving device, and a drilling scale (16) is installed on the surface of or directly below the simulated horizontal wellbore (1) and is placed horizontally; a data acquisition device (17) is connected to an external cable (7) and a camera device (18) to collect operation data of the driving device and experimental image data; a three-dimensional scanning measuring instrument (19) is used to collect the rock cuttings adhesion condition on the surface of the simulated PDC drill bit (10) and the cross-section condition of the drilled simulated mud shale (13); and a constant temperature control device (20) is used to control the temperature in a fixture of the simulated mud shale (13).

2. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 1 is characterized in that: The simulated drill string (3) is equipped with a first centralizer (2), a second centralizer (4) and a universal shaft (5).

3. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 2 is characterized in that: The driving device comprises a waterproof driving motor (6) or a turbine driving rotor (8); the simulated PDC drill bit (10) is electrically driven by the waterproof driving motor (6); the universal joint (5), the waterproof driving motor (6) and the simulated PDC drill bit (10) are connected with a bypass fluid infusion pipe (9), or the simulated PDC drill bit (10) is hydraulically driven by the turbine driving rotor (8).

4. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 3 is characterized in that: The simulated shale (13) fixing device comprises a cylindrical body and a second internal thread plug (15), and the two ends of the cylindrical body are respectively provided with a first internal thread joint (12) and a second external thread joint (14); A first external threaded joint (11) is provided at one end of the simulated horizontal wellbore (1); The first external thread joint (11) and the first internal thread joint (12) are connected via round threads, and the second external thread joint (14) and the second internal thread plug (15) are connected via round threads. The cylindrical body is used to fill simulated shale (13).

5. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 4 is characterized in that: The simulated horizontal wellbore (1) is a transparent tube; the simulated drill string (3) is elastic.

6. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to any one of claims 1 to 5 is characterized in that: It also includes horizontal well drilling rigs; The horizontal well drilling rig comprises a vertical well section centralizer (22), a pressurized liquid infusion joint (23), an input pipe (24), an input pump (25), a simulated fresh mud pool (26), a stirrer (27), an output pipe (28), a simulated return liquid pool (29), a second drilling ruler (30), an anti-overflow pipe (31), and a wellbore fixing device (32); The wellbore fixing device (32) is used to fix the simulated horizontal wellbore (1); the simulated drill string (3) is connected to the vertical well section straightener (22) and the pressurized infusion joint (23); the simulated drilling fluid enters the input pipe (24) and the pressurized infusion joint (23) from the simulated fresh mud pool (26) through the input pump (25); the agitator (27) is placed in the simulated fresh mud pool (26); the returned simulated drilling fluid enters the output pipe (28) and the simulated return fluid pool (29) through the simulated PDC drill bit (10), the annulus between the simulated drill string (3) and the simulated horizontal wellbore (1), and the overflow prevention pipe (31); the simulated drill string (3) is sealedly connected to the overflow prevention pipe (31); a second drilling ruler (30) is vertically arranged outside the overflow prevention pipe (31) for measuring the drilling distance of the simulated drill string (3).

7. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 6 is characterized in that: The simulated PDC drill bit (10) is provided with a plurality of chip removal grooves, blades and nozzles on the outside.

8. The device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for horizontal well drilling according to claim 7 is characterized in that: The simulated PDC drill bit (10) is made of resin or metal, and marks are arranged on the surface of the simulated PDC drill bit (10) in a symmetrical manner.

9. A simulation experimental method for the formation and removal of mud balls in PDC drill bits for horizontal well rotary drilling, characterized in that: A device for simulating the formation and removal of mud balls on the surface of a PDC drill bit for drilling a horizontal well according to claim 8, comprising the following steps: Step 1: Preparation and device construction. The experimental process is as follows: S01 Preparation: preparing simulated shale (13) and simulated drilling fluid; S02 builds a simulation device for the formation and removal of mud bags on the surface of PDC drill bits for horizontal well drilling; S03 sealing test; Step 2: Drilling simulation experiment, the experimental process is as follows: S01 contacting the simulated mud shale (13): pushing the simulated drill string (3) to make the simulated PDC drill bit (10) approach the top of the simulated mud shale (13); S02 Drilling: Turn on the input pump (25), use the waterproof drive motor (6) or the turbine drive rotor (8) to drive the simulated PDC drill bit (10) to rotate, push the simulated drill string (3) at a certain drilling speed, and the simulated PDC drill bit (10) drills the simulated shale (13). The drilling distance can be controlled by the propulsion of the simulated drill string (3) and read by the drilling ruler (16) and the second drilling ruler (16); when a certain drilling distance or drilling time is reached, stop drilling, turn off the input pump (25) and the waterproof drive motor (6), and discharge the simulated drilling fluid from the discharge port (21); S03 Phenomenon observation: The drilling condition of the simulated PDC drill bit (10) in the mud shale can be captured by a three-dimensional scanning measuring instrument (19) and a camera device (18), and the data is recorded in a data acquisition device (17). The drilling process of the simulated PDC drill bit (10) at different positions is followed up in real time through the slideway of the three-dimensional scanning measuring instrument (19); the first external thread joint (11), the first internal thread joint (12), the second external thread joint (14), and the second internal thread plug (15) are opened to measure the accumulation of muddy rock cuttings on the surface of the simulated PDC drill bit (10) and the shape of the top of the simulated mud shale (13); S04 Parameter sensitivity analysis: The waterproof drive motor (6) and the turbine drive rotor (8) control the rotation speed, and observe the drilling condition, wear condition, surface rock cutting adhesion, and rock cutting accumulation of the simulated PDC drill bit (10) at different rotation speeds; the simulated drill string (3) and the drilling ruler (16), the pressurized infusion connector (23) and the second drilling ruler (16) can mark the drilling distance, and observe the wear condition, surface rock cutting adhesion, and rock cutting accumulation of the simulated PDC drill bit (10) at different drilling distances; the input pump (25) adjusts the simulated drilling flow rate and pumping mode; the simulated PDC drill bit (10) analyzes the influence of the nozzle jet on the surface rock cutting adhesion, PDC drill bit drilling, and rock cutting accumulation by opening or closing one or more nozzles on the surface; Step 3: Mud bag removal experiment, the experimental process is as follows: S01: start the device: connect the second internal thread plug (15) to the first external thread connector (11), use the original simulated drilling fluid or the mud pack-removing drilling fluid, turn on the input pump (25) to control the flow rate of the simulated drilling fluid, control the rotation speed of the simulated PDC drill bit (10), and flush the mud pack on the surface of the simulated PDC drill bit (10) and the rock debris accumulated at the bottom of the well; S02 Phenomenon observation: The phenomenon is captured by a three-dimensional scanning measuring instrument (19) and a camera device (18) and recorded in a data acquisition device (17); the first external thread joint (11) and the second internal thread plug (15) are opened to measure the accumulation of muddy rock cuttings on the surface of the simulated PDC drill bit (10); Step 4: Data analysis and result summary: The analysis is conducted based on the experimental data, including the drilling conditions of the drill bit, the formation of mud balls, and the removal of mud balls; the influence of different parameters on the formation and removal of mud balls is analyzed.

10. A horizontal well rotary drilling PDC drill bit mud ball generation-removal simulation experimental method according to claim 9, characterized in that: In step 1, S02 builds a simulation device for the formation and removal of mud bags on the surface of a PDC drill bit for horizontal well drilling, specifically: respectively connect the components of a simulated horizontal wellbore (1), a simulated drill string (3), and a horizontal well drilling rig; the simulated PDC drill bit (10) is close in proportion to the existing PDC drill bit, and the parameters of the chip groove, nozzle, blade, and tooth components are designed, and a water eye flow sensor, a water eye flow pulse regulator, and a control short section can be installed; the simulated horizontal wellbore (1) is fixed by a wellbore fixing device (32), and the simulated drill string (3) is installed into the simulated horizontal wellbore (1); S03 sealing test specifically includes: injecting water into the device through the input pump (25) to ensure that there is no leakage, and draining the water from the drain port (21); The thermostatic control device (20) is turned on to simulate the temperature of the drilling formation; the simulated shale (13) is loaded into the simulated horizontal wellbore (1) from the second internal thread plug (15), and the simulated horizontal wellbore (1) is reconnected; the simulated PDC drill bit (10) is operated without rotation and is at a certain distance from the simulated shale (13), and the simulated drilling fluid is slowly injected by the input pump (25).

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