A true triaxial high-energy rock-breaking experimental device and method

Abstract

The present invention provides a true triaxial high-energy rock-breaking experimental device and method, including a test bench, an intermediate container, a cuttings filter, a back pressure regulator, a drilling fluid tank, a drilling fluid pump, a drilling fluid pipe, an air pump, and an air pipe; the test bench mainly includes a rotary drive mechanism, a drill string system, an axial impact pneumatic shocker, a torsional impact generator, a high-pressure sealing chamber, a rock sample pressure chamber, a confining pressure application mechanism, etc.; the drill string system includes drill pipes, multi-dimensional force sensors, drill bits, etc. The rotary drive mechanism drives the drill string system to rotate through a belt drive mechanism, the axial impact pneumatic shocker and the torsional impact generator provide impact energy for the drill string system, the rock sample pressure chamber applies triaxial pressure to the rock, and the drill bit performs rock-breaking operations on the rock sample. This device can simulate the triaxial pressure environment of the bottom-hole rock, and can study the rock-breaking effect of the drill string system when applying axial impacts and torsional impacts with different frequencies and intensities under different rotational speeds and drilling pressures.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole rock breaking, and specifically to a device and method for conducting a rock axial-torsional combined impact test under triaxial pressure. Background Art

[0002] As China's drilling gradually moves towards deep / ultra-deep layers, problems such as high rock hardness and poor drillability of drill bits have become increasingly serious. Such rocks are usually brittle, have high static pressure resistance, but weak impact resistance, and it is obvious that stick-slip vibration needs to be suppressed during the drilling process to reduce the impact on the drill bit life. Therefore, the concept of downhole axial-torsional combined impact has been proposed. In recent years, many types of axial-torsional combined impactors have emerged on the market and have been applied, but almost none of them can achieve high-energy and high-frequency impacts simultaneously. Therefore, improving the impact energy of the impactor and optimizing the ratio of axial impact to torsional impact are important ways to improve downhole drilling efficiency. Under this idea, studying the frequency ratio of axial impact and torsional impact when the energy is relatively large can have good guiding significance for the subsequent research and development of impactors. In addition, the current indoor axial-torsional combined impact rock breaking test only focuses on the test under non-triaxial pressure and cannot simulate the real pressure situation underground, which will also reduce the credibility of test data.

[0003] Aiming at the above engineering problems and partial defects of the solutions, the present invention combines the characteristics of axial-torsional combined impact and the triaxial pressure exerted on the rock sample, and proposes and designs a device and method for conducting a rock axial-torsional combined impact test under triaxial pressure. Summary of the Invention

[0004] In view of the above background, the present invention provides a device and method for conducting a rock axial-torsional combined impact test under triaxial pressure, which can simulate the triaxial pressure exerted on the rock sample under deep formation conditions, realize axial impact and torsional impact on the rock during the process of the drill bit rotating and drilling down, explore the influence of the energy and frequency of different axial impacts and torsional impacts on the rock breaking efficiency of the rock under different confining pressures and liquid column pressures, and at the same time simulate underbalanced drilling on this basis.

[0005] The technical solution of the present invention is as follows:

[0006] A device for conducting a rock axial-torsional combined impact test under triaxial pressure, comprising a high-pressure sealing cavity fixedly connected to a drilling fluid pipe and an air pipe, the high-pressure sealing cavity is fixedly connected to the upper end cover of the rock sample pressure cavity, the upper end cover of the rock sample pressure cavity is fixedly connected to the rock sample pressure chamber, the high-pressure sealing cavity, the upper end cover of the rock sample pressure cavity and the rock sample pressure chamber are fixed in a test bench, the rock sample pressure chamber is fixedly connected to the side plate of the bench through a positioning through hole of the rock sample pressure cavity, the opening of the rock sample pressure chamber is fixedly connected to the drilling fluid pipe, and the drilling fluid pipe is successively connected in series with the test bench, an intermediate container, a cuttings filter, a back pressure regulator, a drilling fluid sump, and a drilling fluid pump;

[0007] Further, a torsional impact generating mechanism is installed on the inner wall of the bench side plate to generate torsional impact on the drill string system. Above the bench side plate, there is a bench top plate. Above the bench top plate, a belt drive mechanism is installed. The belt drive mechanism includes a driving pulley and a driven pulley. Above the driving pulley, a rotary drive mechanism is installed. The rotary drive mechanism drives the driving pulley to rotate. The belt drive mechanism is fixedly connected to the bench top plate through a bearing cover plate and bearing cover plate bolts. The driven pulley is provided with a spline groove and is connected to the drill string system through a spline. Above the drill string system, a shaft impact pneumatic shocker is installed. The axial impact stress wave generating surface of the shaft impact pneumatic shocker contacts the drill string system. The drill string system enters the rock sample pressure chamber through the hollow part of the high-pressure seal chamber. A rock sample is placed in the rock sample pressure chamber; the confining pressure applying mechanism and the lower end cover of the rock sample pressure cavity are fixedly connected to the rock sample pressure chamber;

[0008] Further, the drill string system mainly includes an upper drill pipe, a multi-dimensional force sensor, a drill pipe connected to the drill bit, and a drill bit. The upper drill pipe is provided with splines for spline rotary drive with the driven pulley. The drill pipe connected to the drill bit is provided with three-section stepped shafts. The first section is provided with an external thread, the second section is provided with a ratchet groove, and the lower half of the third section is hollow, provided with drill pipe water holes and internal threads. The upper drill pipe, the multi-dimensional force sensor, the drill pipe connected to the drill bit, and the drill bit are sequentially fixedly connected through threads;

[0009] Further, sliding rails are vertically fixed on both sides of the inner wall of the bench side plate. A torsional impact pneumatic shocker is installed on the sliding rails. The impact rod of the torsional impact pneumatic shocker impacts the impact block on the torsional impact disc, and then drives the pawl to impact the ratchet groove, and then the drill string system can be subjected to torsional impact;

[0010] Further, the high-pressure seal chamber and the rock sample pressure chamber should be in a strictly sealed environment. The high-pressure seal chamber is equipped with a drill pipe high-pressure floating seal group and a limit sealing ring, which are closely attached to the outer surface of the drill pipe connected to the drill bit and the hollow surface of the high-pressure seal chamber body. The hollow part of the upper end cover of the rock sample pressure cavity is equipped with a rock sample pressure chamber sealing ring, which is closely attached to the outer surface of the drill pipe connected to the drill bit and the hollow surface of the upper end cover of the rock sample pressure cavity;

[0011] Further, the confining pressure applying mechanism can generate confining pressure on the rock sample. Through a servo pump connected externally through a hydraulic hole, a certain amount of hydraulic pressure is applied to the confining pressure piston, and the hydraulic piston is used to push the rock sample circumferential compression block to compress the rock sample;

[0012] Further, the rock sample should be a cuboid, and when placed in the rock sample pressure cavity, its four sides should be parallel to the four inner side walls. The upper surface and the lower surface of the rock sample are respectively provided with a rock sample axial compression block and an axial plunger to limit the vertical displacement of the rock sample; the drill bit drills from the upper surface of the rock sample; the axial plunger can be installed with an empty lower plug for directly installing a vibration or stress sensor on the lower surface, or an outflow lower plug for establishing a rock pore pressure model to simulate underbalanced drilling;

[0013] Furthermore, through holes corresponding to each other are provided on the end cover of the high-pressure sealing cavity and the high-pressure sealing cavity body. High-pressure sealing cavity bolts are used to fixedly connect the end cover of the high-pressure sealing cavity and the high-pressure sealing cavity body, and are threadedly connected to the threaded holes of the high-pressure sealing cavity bolts on the upper end cover of the rock sample pressure cavity body; the upper end cover of the rock sample pressure cavity body is also provided with through holes for bolts of the upper end cover of the rock sample pressure cavity body, corresponding to the threaded holes for bolts of the upper end cover of the rock sample pressure cavity body one by one. Bolts of the upper end cover of the rock sample pressure cavity body are used to fixedly connect the upper end cover of the rock sample pressure cavity body and the rock sample pressure cavity body;

[0014] On four sides of the rock sample pressure cavity body, stepped holes for confining pressure pistons are provided for placing the confining pressure applying mechanism, and threaded holes for positioning the confining pressure pistons are provided, so that positioning bolts of the rock sample pressure cavity body fixedly connect the confining pressure applying mechanism and the rock sample pressure cavity body;

[0015] The threaded holes for bolts of the lower end cover of the rock sample pressure cavity body correspond to the bolt through holes of the lower end cover of the rock sample pressure cavity body one by one. Bolts of the lower end cover of the rock sample pressure cavity body fixedly connect the lower end cover of the rock sample pressure cavity body and the rock sample pressure cavity body;

[0016] Furthermore, the flow of drilling fluid in the test bench enters the drill pipe water eye from the drilling fluid injection hole, flows through the lower half of the hollow part of the drill pipe connected to the bit to reach the bit, flows out from the nozzles of the bit, passes through the annular cavity drain port and enters the rock sample pressure cavity body, and then flows out from the drilling fluid drain hole provided on the rock sample pressure cavity body; the flow of the air current generated by the air pump in the test bench, except for entering from the air pump interface, the rest of the flow process is the same as that of the drilling fluid.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. Simulate the confining pressure and liquid column pressure conditions suffered by the rock sample during the drilling process;

[0019] 2. Provide axial impact and torsional impact with different frequencies and intensities during the process of lowering the drill string system, and at the same time, the mechanical drilling speed and drilling pressure can be adjusted;

[0020] 3. Can monitor in real time the force and torque conditions in three directions of the drill string system during the process of lowering the drill string;

[0021] 4. The circulation of the drilling fluid can simulate the flow of the drilling fluid during the actual process of lowering the drill string. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of a device for performing a rock axial torsion composite impact test under triaxial pressure;

[0023] Figure 2 It is a left view of the test bench;

[0024] Figure 3 It is Figure 2 The sectional view of part A-A in

[0025] Figure 4 is Figure 3 a partial enlarged view of part Ⅰ in

[0026] Figure 5 is Figure 2 a sectional view taken along line B-B in

[0027] Figure 6 is a half-sectional view of the structure after the rotary drive mechanism, pulley drive mechanism and the top plate of the bench are assembled;

[0028] Figure 7 is a schematic structural diagram of the drill string system and the axial impact pneumatic jar after assembly;

[0029] Figure 8 is a schematic structural diagram of the drill pipe with the drill bit attached;

[0030] Figure 9 is a schematic structural diagram of the torsional impact disc and the pawl after assembly;

[0031] Figure 10 is a sectional view of the structure of the high-pressure sealing cavity;

[0032] Figure 11 is a sectional view of the structure of the high-pressure floating seal group of the drill pipe;

[0033] Figure 12 is a sectional view of the structure of the axial pressing block for the rock sample;

[0034] Figure 13 is a sectional view of the structure of the upper end cover of the rock sample pressure chamber;

[0035] Figure 14 is a sectional view of the structure of the confining pressure piston housing;

[0036] Figure 15 is a sectional view of the structure of the rock sample pressure chamber;

[0037] Figure 16 is a schematic structural diagram of the side plate structure of the bench.

[0038] In the figure:

[0039] 1. Rotary drive mechanism; 2. Axial impact pneumatic jar; 3. Pulley drive mechanism; 4. Drill string system; 5. Torsional impact generating mechanism; 6. High-pressure sealing cavity; 7. Upper end cover of the rock sample pressure chamber; 8. Rock sample pressure chamber; 9. Confining pressure applying mechanism; 10. Lower end cover of the rock sample pressure chamber; 11. Top plate of the bench; 12. Side plate of the bench; 13. Bottom plate of the bench; 14. Test bench; 15. Intermediate container; 16. Chip filter; 17. Back pressure regulator; 18. Drilling fluid tank; 19. Drilling fluid pump; 20. Drilling fluid pipe; 21. Air pump; 22. Air pipe.

[0040] 101. Rotating drive motor; 102. Rotating transmission shaft housing; 103. Rotating transmission shaft; 104. Rotating transmission shaft housing bolt; 301. Driving pulley; 302. Driven pulley; 303. Bearing cover plate; 304. Belt pulley radial bearing; 305. Belt pulley thrust bearing; 306. Bearing cover plate bolt; 401. Upper drill pipe; 402. Multi-dimensional force sensor; 403. Drill pipe connected to drill bit; 404. Collar; 405. Drill bit; 406. Collar thrust bearing; 407. Twist impact disc thrust bearing; 408. Ratchet groove; 409. Drill pipe water eye; 501. Twist impact pneumatic shocker; 502. Slide rail; 503. Twist impact disc; 504. Pawl; 505. Spring; 506. Impact block; 601. High-pressure seal cavity bolt; 602. High-pressure seal cavity end cover; 603. High-pressure seal cavity body; 604. Plug; 605. Drill pipe high-pressure floating seal group; 606. Drilling fluid injection hole; 607. Oil filling port; 608. High-pressure seal cavity through hole; 609. High-pressure floating seal group fixing bolt threaded hole; 610. Air pump interface; 611. Limit sealing ring; 612. Sealing ring limit bolt; 701. Upper end cover of rock sample pressure cavity; 702. Upper end cover bolt of rock sample pressure cavity; 703. Sealing ring of rock sample pressure chamber; 704. Through hole of upper end cover bolt of rock sample pressure cavity; 705. Threaded hole of high-pressure seal cavity bolt; 706. Threaded hole of limit sealing ring; 801. Rock sample pressure cavity; 802. Drilling fluid drainage hole; 803. Rock sample pressure cavity positioning bolt; 804. Rock sample circumferential pressing block; 805. Rock sample axial pressing block; 806. Square rubber sleeve; 807. Rock sample; 808. Plunger collar; 809. Axial plunger; 810. Lower end cover bolt of rock sample pressure cavity; 811. Upper through hole of rock sample pressure cavity; 812. Confining pressure piston stepped hole; 813. Rock sample pressure cavity positioning threaded hole; 814. Confining pressure piston positioning threaded hole; 815. Annular cavity drainage port; 816. Threaded hole of upper end cover bolt of rock sample pressure cavity; 817. Lower end cover stepped hole of rock sample pressure cavity; 818. Threaded hole of lower end cover bolt of rock sample pressure cavity;; 901. Confining pressure piston housing; 902. Confining pressure piston; 903. Confining pressure piston housing bolt; 904. Confining pressure piston housing through hole; 905. Hydraulic hole; 1201. Rock sample pressure cavity positioning through hole; 1202; Confining pressure piston positioning through hole.

[0041] 605a. Outer sealing rubber ring; 605b. Rubber retaining ring; 605c. Inner sealing rubber ring group; 605d. Floating sealing ring bolt. Specific implementation manner

[0042] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in this text, words such as "upper" and "lower" are only used for convenience in describing the drawings, and do not limit the directions in actual use, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0043] Referring to Figures 1 - 16 As shown, the present invention provides a rock axial-torsional composite impact test device under triaxial pressure, which includes a test bench 14, an intermediate container 15, a cuttings filter 16, a back pressure regulator 17, a drilling fluid tank 18, a drilling fluid pump 19, an air pump 21. The drilling fluid pipe 20 connects the test bench 14, the intermediate container 15, the cuttings filter 16, the back pressure regulator 17, the drilling fluid tank 18, and the drilling fluid pump 19, and the air pipe 22 connects the test bench 14 and the air pump 21;

[0044] Furthermore, the test bench 14, the intermediate container 15, the cuttings filter 16, the back pressure regulator 17, the drilling fluid tank 18, and the air pump 21 are placed on the same horizontal plane, and the drilling fluid pump 19 is placed on the extension platform of the drilling fluid tank 18;

[0045] Furthermore, the test bench 14 includes, from top to bottom and from left to right in sequence, a rotary drive mechanism 1, an axial impact pneumatic shocker 2, a belt drive mechanism 3, a drill string system 4, a bench top plate 11, bench side plates 12, a torsional impact generating mechanism 5, a high-pressure seal cavity end cover 602, a high-pressure seal cavity 6, an upper end cover 7 of the rock sample pressure chamber, a rock sample pressure chamber 8, a confining pressure applying mechanism 9, a lower end cover 10 of the rock sample pressure chamber, and a bench bottom plate 13;

[0046] Furthermore, 1 includes, from top to bottom in sequence, a rotary drive motor 101, a rotary drive shaft housing 102, a rotary drive shaft 103, and rotary drive shaft housing bolts 104. The rotary drive shaft housing 102 is fixedly connected to the bearing cover plate 303 through the rotary drive shaft housing bolts 104. The rotary drive motor 101 is placed on the top surface of the rotary drive shaft housing 102. The rotary main shaft of the rotary drive motor 101 and the rotary drive shaft 103 are provided with flat key keyways. The rotary drive motor 101 is connected to the rotary drive shaft 103, and the rotary drive shaft 103 is connected to the driving pulley 301 through flat keys;

[0047] Further, the driving pulley 301 and the driven pulley 302 are driven by a belt. There is a stepped toroidal surface for placing the pulley radial bearing 304 above, and an annular groove for placing the pulley thrust bearing 305 below. The hub of the driven pulley 302 is provided with a flat key keyway and a spline keyway. The bearing cover bolts 306 fix the bearing cover 303, the pulley radial bearing 304, the driving pulley 301, the driven pulley 302, and the pulley thrust bearing 305 on the top plate 11 of the bench;

[0048] Further, the drill string system 4 successively includes an upper drill pipe 401, a multi-dimensional force sensor 402, a drill pipe connected to the drill bit 403, and a drill bit 405 from top to bottom. An axle collar 404, an axle collar thrust bearing 406, and a rotary percussion disc thrust bearing 407 are installed on the drill pipe 403 connected to the drill bit. The upper end surface of the upper drill pipe 401 is in surface contact with the impact surface of the shaft impact pneumatic shocker 2 of the shaft impact. The axial impact stress wave is transmitted along the upper drill pipe 401, the multi-dimensional force sensor 402, and the drill pipe 403 connected to the drill bit to the drill bit 405 to achieve shaft impact rock breaking. The upper drill pipe 401 has a spline on the toroidal surface and a thread at the lower end. The upper drill pipe 401 is threadedly connected to the multi-dimensional force sensor 402;

[0049] Further, the drill pipe 403 connected to the drill bit is provided with three stepped shafts, which are respectively recorded as the first stepped shaft, the second stepped shaft, and the third stepped shaft from top to bottom. The two shaft shoulders are respectively recorded as the first shaft shoulder and the second shaft shoulder from top to bottom. The upper part of the first stepped shaft is provided with a thread and is threadedly connected to the multi-dimensional force sensor 402. Six non-through ratchet grooves 408 are opened on the second stepped shaft from the first shaft shoulder to the second shaft shoulder and are evenly distributed circumferentially along the second stepped shaft. The vertical distance from the lower end surface of the ratchet groove to the second shaft shoulder is the axial height of the rotary percussion disc thrust bearing 407. The lower half of the third stepped shaft is hollow and is provided with an internal thread to ensure the threaded connection between the drill bit 405 and the drill pipe 403 connected to the drill bit. At the same time, a drill pipe water eye 409 is opened on one side of the upper end of the hollow part to ensure that the drilling fluid enters the hollow part of the drill pipe 403 connected to the drill bit;

[0050] Further, the rotary percussion mechanism 5 includes a rotary percussion pneumatic shocker 501, a slide rail 502, a rotary percussion disc 503, a pawl 504, and a spring 505. There are two slide rails 502, which are respectively placed on the inner walls of the side plates 12 of the bench, with the placement direction perpendicular to the horizontal plane and centrosymmetric about the center of the drill string system 4. The rotary percussion pneumatic shocker 501 is installed on the slide rail 502 and can move vertically along the slide rail 502. The impact rod of the rotary percussion pneumatic shocker 501 impacts the impact block 506 of the rotary percussion disc 503 to generate a certain amount of torque and transmit it to the pawl 504. The pawl 504 then impacts the ratchet groove 408 of the drill pipe 403 connected to the drill bit to achieve the effect of rotary percussion rock breaking. The spring 505 can ensure that the pawl 504 is always in contact with the ratchet groove 408;

[0051] Further, during the process of axial torsion and compound impact rock breaking, the end cover 602 of the high-pressure sealing cavity, the high-pressure sealing cavity 6, the upper end cover 7 of the rock sample pressure cavity, the rock sample pressure chamber 8, the outer shell 901 of the confining pressure piston, the confining pressure piston 902, and the lower end cover 10 of the rock sample pressure cavity need to ensure strict sealing performance;

[0052] Further, the high-pressure sealing cavity 6 includes a high-pressure sealing cavity body 603, a plug 604, a drill pipe high-pressure floating seal group 605, a drilling fluid injection hole 606, an oil filling port 607, and a high-pressure sealing cavity through hole 608. The drill pipe high-pressure floating seal group 605 is closely attached to the drill pipe 403 with the bit to prevent the drilling fluid from overflowing through the gap at the end cover 602 of the high-pressure sealing cavity. The lubricating oil / grease required for the drill pipe high-pressure floating seal group 605 is added through the oil filling port 607. After the drilling fluid injection hole 606 is externally connected to the drilling fluid pipe 20, drilling fluid can be injected. 610 is externally connected to the air pump 21 through the air pipe 22;

[0053] The high-pressure sealing cavity through hole 608 is a through hole for connecting eight high-pressure sealing cavity bolts 601, which are evenly distributed circumferentially and correspond one by one to the eight through holes of the end cover 602 of the high-pressure sealing cavity and the eight high-pressure sealing cavity bolt threaded holes 705 of the upper end cover 701 of the rock sample pressure cavity. At the same time, the hollow part of the high-pressure sealing cavity body 603 is a stepped hole. Eight high-pressure floating seal group fixing bolt threaded holes 609 are opened on the first shoulder and are evenly distributed circumferentially. After the drill pipe high-pressure floating seal group 605 and the limit sealing ring 611 are sequentially placed into the hollow part of the high-pressure sealing cavity body 603, they are fixed with the sealing ring limit bolts 612;

[0054] Further, the drill pipe high-pressure floating seal group 605 includes a sealing outer rubber ring 605a, a rubber retaining ring 605b, a sealing inner rubber ring group 605c, and a floating sealing ring bolt 605d. The floating sealing ring bolt 605d plays a role in connecting and fastening;

[0055] Further, the upper end cover 701 of the rock sample pressure cavity is provided with sixteen through holes for the bolts of the upper end cover of the rock sample pressure cavity 704, which correspond one by one to the threaded holes 816 for the bolts of the upper end cover of the rock sample pressure cavity;

[0056] A stepped hole is opened in the center of the upper end cover 701 of the rock sample pressure cavity, and the sealing ring 703 of the rock sample pressure chamber and the threaded hole 706 for the limit sealing ring are threadedly connected with screws;

[0057] Further, the high-pressure sealing cavity bolts 601 fix the end cover 602 of the high-pressure sealing cavity and the high-pressure sealing cavity body 603 on the upper end cover 701 of the rock sample pressure cavity, and the bolts 702 of the upper end cover of the rock sample pressure cavity fix the upper end cover 701 of the rock sample pressure cavity on the rock sample pressure cavity 801;

[0058] Further, according to Figure 3In terms of the viewing direction, on the upper surface of the rock sample pressure cavity 801, there are a through hole 811 above the rock sample pressure cavity and sixteen bolt threaded holes 816 for the upper end cover of the rock sample pressure cavity evenly distributed in a circle. On the four surrounding side surfaces, there are stepped holes 812 for the confining pressure piston and twelve positioning threaded holes 814 for the confining pressure piston evenly distributed in a circle. On the left and right sides, there are positioning threaded holes 813 for the rock sample pressure cavity, which respectively correspond one-to-one with the through holes 1201 for the rock sample pressure cavity positioning on the side plate 12 of the test bench. At the same time, a drilling fluid drainage hole 802 is opened along the lower left of the inner cavity of the rock sample pressure cavity 801 to ensure the smooth outflow of the drilling fluid. On the lower surface, there are a stepped hole 817 for the lower end cover of the rock sample pressure cavity and twelve bolt threaded holes 818 for the lower end cover of the rock sample pressure cavity evenly distributed in a circle;

[0059] Further, the outer shell 901 of the confining pressure piston has an interference fit with both the positioning through hole 1202 for the confining pressure piston and the stepped hole 812 for the confining pressure piston. At the same time, it is ensured that the outer end surface of the outer shell 901 of the confining pressure piston is flush with the outer surface of the side plate 12 of the test bench. The confining pressure piston 902 cooperating with the outer shell 901 of the confining pressure piston can move along its own axis direction under the pressure applied by the servo pump externally connected to the hydraulic hole 905, and drive the circumferential compaction block 804 of the rock sample to move, generating a confining pressure on the rock sample 807;

[0060] Further, the rock sample 807 is sleeved with a square rubber sleeve 806 to reduce the influence of surface roughness on the magnitude of the confining pressure received;

[0061] Further, the axial compaction block 805 of the rock sample is composed of a hollow secondary stepped shaft and a cuboid. The shoulder with a relatively larger surface diameter is in surface contact with the upper end cover 701 of the rock sample pressure cavity. The second stepped shaft is provided with a ring cavity drainage port 815. The lower end surface of the axial compaction block 805 of the rock sample is in contact with the square rubber sleeve 806 on the upper surface of the rock sample 807 to limit the vertical displacement of the rock sample 807.

[0062] Further, the axial plunger 809 is in contact with the square rubber sleeve 806 on the lower surface of the rock sample 807 to generate a supporting force on the rock sample 807. At the same time, an empty lower plug can be installed on the axial plunger 809 for directly installing a vibration or stress sensor on the lower surface, or a flowing-down lower plug can be installed for establishing a rock pore pressure model to simulate underbalanced drilling;

[0063] Further, the plunger shaft ring 808 is used for the support between the axial plunger 809 and the lower end cover 10 of the rock sample pressure cavity. The bolt 903 for the outer shell of the confining pressure piston fixes the outer shell 901 of the confining pressure piston on the rock sample pressure cavity 801. The bolt 810 for the lower end cover of the rock sample pressure cavity fixes the lower end cover 10 of the rock sample pressure cavity on the rock sample pressure cavity 801. The positioning bolt 803 for the rock sample pressure cavity and the outer shell 901 of the confining pressure piston fix the rock sample pressure cavity 801 on the side plate 12 of the test bench;

[0064] Further, the drilling fluid is pumped out from the drilling fluid tank 18 by the drilling fluid pump 19. Through the connection of the drilling fluid pipe 20, the circulating flow direction is: the drilling fluid pump 19, the drilling fluid injection hole 606, the drill pipe water eye 409, the hollow part of the drill pipe with bit 403, the bit 405, the annular cavity drain port 815, the intermediate container 15, the cuttings filter 16, the back pressure valve 17, and the drilling fluid tank 18;

[0065] Further, the intermediate container 15 includes an automatic pump and a well fluid pressure sensor. The hydrostatic pressure sensor and the back pressure valve 17 can ensure the high hydraulic pressure state in the high-pressure seal cavity 6 and the rock sample pressure chamber 8;

[0066] Further, after completing a set of axial torsion composite impact tests, the air pump 21 connected to the air pipe 22 can apply air pressure to the high-pressure seal cavity 6 to discharge the remaining drilling fluid.

[0067] A method for conducting a rock axial torsion composite impact test under triaxial pressure includes the following steps:

[0068] Step 1. Open the lower end cover 10 of the rock sample pressure cavity, and remove the axial plunger 809, the plunger shaft collar 808, and the rock sample axial pressing block 805. After the rock sample 807 is sleeved with the upper rubber sleeve 806, it is placed between the axial plunger 809 and the rock sample axial pressing block 805. Then the whole is installed and placed in the rock sample pressure cavity 801, and try to ensure that the circumferential surface around the rock sample 807 is parallel to the inner wall of the rock sample pressure cavity 801. The lower end cover bolt 810 of the rock sample pressure cavity seals the lower end cover 10 of the rock sample pressure cavity;

[0069] Step 2. The hydraulic hole 905 is externally connected to a servo pump and hydraulic oil is injected into it. After the confining pressure piston 902 is pressured, it moves towards the rock sample 807, driving the rock sample circumferential pressing block 804 to squeeze the rock sample 807 and generate confining pressure;

[0070] Step 3. Lower the drill string system 4 so that the bit 405 contacts the upper surface of the rock sample 807;

[0071] Step 4. Start the rotary drive motor 101 and apply a certain bit pressure. The bit 405 pre-scrapes the rock sample 807 to a certain extent. When a certain area of the cutting teeth of the bit 405 contacts the surface of the rock sample 807, turn off the rotary drive motor 101, start the drilling fluid pump 19, and use the drilling fluid to carry the cuttings out of the rock sample pressure cavity 801;

[0072] Step 5. After the drilling fluid returns to the drilling fluid tank 18 along the drilling fluid pipe 20, start the back pressure valve 17 and preset the pressure value;

[0073] Step 6. After the hydrostatic pressure sensor of the intermediate container 15 reaches the target value, start the rotary drive motor 101, the axial impact pneumatic shocker 2, and the torsional impact pneumatic shocker 501. Observe the data such as the bit penetration, the drilling pressure, and the drill string torque in real time through the data collector externally connected to the multi-dimensional force sensor 402. After drilling to the predetermined depth, turn off the torsional impact pneumatic shocker 501, the axial impact pneumatic shocker 2, and the rotary drive motor 101, and raise the drill string system 4 to the initial height;

[0074] Step 7. After the drill string system 4 is raised to the initial height, slowly reset the pressure value set by the back pressure regulator 17 to zero;

[0075] Step 8. After the value displayed by the hydrostatic pressure sensor attached to the intermediate container 15 is zero, turn off the servo pump externally connected to the hydraulic hole 905, eliminate the confining pressure of the rock sample 807, turn off the drilling fluid pump 19, turn on the air pump 21, and observe the drilling fluid discharge port of the drilling fluid pipe 20 at the drilling fluid tank 18;

[0076] Step 9. After the drilling fluid discharge port of the drilling fluid pipe 20 at the drilling fluid tank 18 no longer discharges drilling fluid, turn off the air pump 21;

[0077] Step 10. After the air pump 21 is turned off, remove the lower end cover 10 of the rock sample pressure chamber, take out the axial plunger 809, the plunger shaft ring 808, the rock sample 807, the square rubber sleeve 806, and the rock sample axial pressing block 805, and clean the residual drilling fluid and rock cuttings in the rock sample pressure chamber 801;

[0078] Step 11. For a new round of tests, just repeat Steps 1 - 10.

[0079] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A rock axial torsion composite impact test device under triaxial pressure, characterized in that It includes a test bench (14), a high-pressure sealing chamber (6), a rock sample pressure chamber (8), a drill string system (4), a torsional impact generating mechanism (5), an axial impact pneumatic shocker (2) and a drilling fluid circulation system; the test bench (14) is composed of a bench top plate (11), bench side plates (12) and a bench bottom plate (13), and the bench side plates (12) are fixedly connected to the rock sample pressure chamber (8) through the rock sample pressure cavity positioning through holes (1201); the high-pressure sealing chamber (6) is fixedly connected to the drilling fluid pipe (20) and the air pipe (22); the inner cavity of the rock sample pressure chamber (8) is provided with a confining pressure applying mechanism (9) and a rock sample (807), the upper end cover (701) of the rock sample pressure cavity is arranged at the top of the rock sample pressure chamber (8), and the confining pressure applying mechanism applies confining pressure to the rock sample through a confining pressure piston (902); the drill string system (4) includes an upper drill pipe (401), a multi-dimensional force sensor (402), a drill pipe connected to the drill bit (403) and a drill bit (405), the drill pipe connected to the drill bit (403) is provided with a ratchet groove (408) and a drill pipe water hole (409), and is in sealing fit with the hollow part of the high-pressure sealing chamber (6); the torsional impact generating mechanism (5) includes a slide rail (502), a torsional impact pneumatic shocker (501), a torsional impact disc (503) and a pawl (504); the axial impact pneumatic shocker (2) contacts the upper drill pipe (401) and is used to apply an axial impact; the drilling fluid circulation system includes a drilling fluid pump (19), an intermediate container (15), a cuttings filter (16) and a back pressure valve (17), and the drilling fluid is injected into the rock sample pressure chamber (8) through the drill pipe water hole (409) and discharged through the annular cavity drain port (815).

2. The rock axial torsion composite impact test device under triaxial pressure according to claim 1, characterized in that The torsional impact generating mechanism (5) is installed on the inner wall of the bench side plate (12) to generate a torsional impact on the drill string system (4). The bench top plate (11) is placed above the bench side plate (12), and a belt drive mechanism (3) is installed above the bench top plate (11). The belt drive mechanism (3) includes a driving pulley (301) and a driven pulley (302). A rotary drive mechanism (1) is installed above the driving pulley. The rotary drive mechanism (1) drives the driving pulley (301) to rotate. The belt drive mechanism (3) is fixedly connected to the bench top plate (11) through a bearing cover plate (303) and bearing cover plate bolts (306). The driven pulley (302) is provided with a spline groove and is connected to the drill string system (4) through a spline. An axial impact pneumatic shocker (2) is installed above the drill string system. The axial impact stress wave generating surface of the axial impact pneumatic shocker (2) contacts the drill string system (4). The drill string system (4) enters the rock sample pressure chamber (8) through the hollow part of the high-pressure sealing chamber (6).

3. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 1, characterized in that, The upper drill pipe (401) is provided with splines for spline rotational drive with the driven pulley (302). The drill pipe with drill bit (403) is provided with a three-stage stepped shaft. The first stage is provided with an external thread, the second stage is provided with a ratchet groove (408), the lower half of the third stage is hollow and is provided with a drill pipe water hole (409) and an internal thread. The upper drill pipe (401), the multi-dimensional force sensor (402), the drill pipe with drill bit (403) and the drill bit (405) are fixedly connected in sequence by threads.

4. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 1, characterized in that, The slide rails (502) are vertically fixed on both sides of the inner wall of the bench side plate (12). The twist impact pneumatic shocker (501) is installed on the slide rails (502). The impact rod of the twist impact pneumatic shocker (501) impacts the impact block (506) on the twist impact disc (503), thereby driving the pawl (504) to impact the ratchet groove (408) of the drill pipe with drill bit (403), and then the drill string system (4) can be subjected to torsional impact.

5. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 1, characterized in that, The high-pressure sealing chamber (6) and the rock sample pressure chamber (8) should be in a strictly sealed environment. The high-pressure sealing chamber (6) is equipped with a drill pipe high-pressure floating seal group (605) and a limit sealing ring (611), which are in close fit with the outer surface of the drill pipe with drill bit (403) and the hollow surface of the high-pressure sealing cavity body (603). The hollow part of the upper cover (701) of the rock sample pressure cavity is equipped with a rock sample pressure chamber sealing ring (703), which is in close fit with the outer surface of the drill pipe with drill bit (403) and the hollow surface of the upper cover (701) of the rock sample pressure cavity.

6. A device for conducting a combined axial torsion and impact test on a rock under triaxial pressure according to claim 1, characterized in that, The confining pressure applying mechanism (9) is fixedly connected to the rock sample pressure chamber (8) and can generate confining pressure on the rock sample (807). A servo pump connected externally through a hydraulic hole (905) applies a certain amount of hydraulic pressure to the confining pressure piston (902), and the confining pressure piston (902) pushes the rock sample circumferential pressing block (804) to squeeze the rock sample (807).

7. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 6, characterized in that, The rock sample (807) should be a cuboid, and when placed in the rock sample pressure cavity (801), its four sides should be parallel to the four inner side walls. The upper surface and the lower surface of the rock sample (807) are respectively provided with a rock sample axial pressing block (805) and an axial plunger (809) to limit the vertical displacement of the rock sample (807); the drill bit (405) drills down from the upper surface of the rock sample (807); the axial plunger (809) can be installed with an empty lower plug for directly installing a vibration or stress sensor on the lower surface, or installed with a flowing-down lower plug for establishing a rock pore pressure model to simulate underbalanced drilling.

8. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 5, characterized in that, The end cover (602) of the high-pressure sealing cavity and the high-pressure sealing cavity body (603) are provided with through holes corresponding to each other one by one. The high-pressure sealing cavity bolt (601) fixes the end cover (602) of the high-pressure sealing cavity and the high-pressure sealing cavity body (603), and is threadedly connected to the high-pressure sealing cavity bolt threaded hole (705) on the upper end cover (701) of the rock sample pressure cavity body; the upper end cover (701) of the rock sample pressure cavity body is also provided with a bolt through hole (704) for the upper end cover of the rock sample pressure cavity body, which corresponds to the bolt threaded hole (816) for the upper end cover of the rock sample pressure cavity body one by one. The bolt (702) for the upper end cover of the rock sample pressure cavity body fixes the upper end cover (701) of the rock sample pressure cavity body and the rock sample pressure cavity body (801). Four side surfaces of the rock sample pressure cavity body (801) are all provided with stepped holes (812) for the confining pressure piston to place the confining pressure applying mechanism (9), and are provided with positioning threaded holes (814) for the confining pressure piston, so that the positioning bolt (803) of the rock sample pressure cavity body fixes the confining pressure applying mechanism (9) and the rock sample pressure cavity body (801). The bolt threaded hole (818) of the lower end cover of the rock sample pressure cavity body corresponds to the bolt through hole of the lower end cover (10) of the rock sample pressure cavity body one by one. The bolt (810) of the lower end cover of the rock sample pressure cavity body fixes the lower end cover (10) of the rock sample pressure cavity body and the rock sample pressure cavity body (801).

9. A device for conducting a rock axial torsion composite impact test under triaxial pressure according to claim 1, characterized in that, The drilling fluid flows in the test bench (14) from the drilling fluid injection hole (606) into the drill pipe water eye (409) of the drill pipe (403) connecting the bit, flows through the lower half hollow part of the drill pipe (403) connecting the bit to the bit (405), flows out from the nozzle of the bit (405), passes through the annular cavity drain port (815) and enters the rock sample pressure cavity body (801), and then flows out from the drilling fluid drain hole (802) opened on the rock sample pressure cavity body (801); the air flow generated by the air pump (21) flows in the test bench (14) in the same way as the drilling fluid except that it enters from the air pump interface (610).

10. A method for conducting a rock axial torsion composite impact test under triaxial pressure, characterized in that, It includes the following steps: Step 1. Open the lower end cover (10) of the rock sample pressure cavity body, and remove the axial plunger (809), the plunger shaft ring (808) and the rock sample axial pressing block (805). After the rock sample (807) is sleeved with the upper rubber sleeve (806), it is placed between the axial plunger (809) and the rock sample axial pressing block (805), and then the whole is installed and placed in the rock sample pressure cavity body (801). Try to ensure that the circumferential surface around the rock sample (807) is parallel to the inner wall of the rock sample pressure cavity body (801). The bolt (810) of the lower end cover of the rock sample pressure cavity body seals the lower end cover (10) of the rock sample pressure cavity body. Step 2. The hydraulic hole (905) is externally connected to a servo pump and hydraulic oil is injected into it, so that the confining pressure piston (902) moves towards the rock sample (807) under pressure, driving the rock sample circumferential pressing block (804) to squeeze the rock sample (807) and generate confining pressure. Step 3. Lower the drill string system (4) so that the bit (405) contacts the upper surface of the rock sample (807). Step 4. Start the rotary drive motor (101) and apply a certain bit weight. The drill bit (405) pre-scrapes the rock sample (807) to a certain extent. When a certain area of the cutting teeth of the drill bit (405) comes into contact with the surface of the rock sample (807), turn off the rotary drive motor (101). Start the mud pump (19) and use the drilling fluid to carry the cuttings out of the rock sample pressure chamber (801); Step 5. After the drilling fluid returns to the mud pit (18) along the mud pipe (20), start the back pressure regulator (17) and preset the pressure value; Step 6. After the hydrostatic pressure sensor of the intermediate container (15) reaches the target value, start the rotary drive motor (101), the axial impact pneumatic shocker (2) and the torsional impact pneumatic shocker (501). Real-time observe data such as bit penetration, bit weight, and drill string torque through the data collector externally connected to the multi-dimensional force sensor (402). After drilling to the predetermined depth, turn off the torsional impact pneumatic shocker (501), the axial impact pneumatic shocker (2) and the rotary drive motor (101), and raise the drill string system (4) to the initial height; Step 7. After the drill string system (4) is raised to the initial height, slowly return the pressure value set by the back pressure regulator (17) to zero; Step 8. After the value of the hydrostatic pressure sensor attached to the intermediate container (15) shows zero, turn off the servo pump externally connected to the hydraulic hole (905) to eliminate the confining pressure of the rock sample (807). Turn off the mud pump (19), turn on the air pump (21), and observe the mud discharge port of the mud pipe (20) at the mud pit (18); Step 9. After the mud discharge port of the mud pipe (20) at the mud pit (18) no longer discharges mud, turn off the air pump (21); Step 10. After the air pump (21) is turned off, remove the lower end cover (10) of the rock sample pressure chamber, take out the axial plunger (809), the plunger shaft ring (808), the rock sample (807), the square rubber sleeve (806) and the rock sample axial pressing block (805), and clean the remaining drilling fluid and cuttings in the rock sample pressure chamber (801); Step 11. For a new round of tests, just repeat Steps 1 - 10.

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