A coring device for high-confined water formation and its coring method

Abstract

The present invention discloses a coring device for high-confined water strata. It includes a casing structure, a casing joint, and a structure for preventing water gushing from the drill pipe; a plurality of casing structures are longitudinally connected through the casing joint; the drill pipe passes through the casing structure and the casing joint from top to bottom, and the lower end is connected to the structure for preventing water gushing from the drill pipe; the structure for preventing water gushing from the drill pipe is located above the core barrel; a mud inlet hole and a drainage hole are provided on the structure for preventing water gushing from the drill pipe; the mud inlet hole is vertically arranged; the drainage hole is horizontally arranged; a one-way valve for the mud hole is located at the lower end of the mud inlet hole; a one-way valve for the water outlet hole is arranged at the outlet end of the drainage hole; a water pressure sensor is arranged at the outlet end of the drainage hole and is located inside the one-way valve for the water outlet hole. The present invention has the advantages of improving the quality of the drilling hole, ensuring the coring in the high-confined water strata, maintaining the long-term stability of the drilling hole after coring, and reducing the occurrence of disasters. The present invention also discloses a coring method for the coring device for high-confined water strata.

Description

Technical Field

[0001] The present invention relates to a core sampling device for high-confined water strata. The present invention also relates to a core sampling method for the core sampling device when used in high-confined water strata. Background Art

[0002] During the construction of projects such as water conservancy and hydropower, mining, and hydrogeological monitoring, geological exploration of the underground strata conditions is required to analyze the lithological conditions of the strata, and thus provide a feasibility study basis for the smooth progress of subsequent projects. Drilling core sampling, as a commonly used technical means for analyzing geological conditions, is widely used in fields such as drilling. In drilling exploration, high-quality boreholes are the key to ensuring core sampling. However, as the drilling depth increases, the groundwater conditions become more complex, and the problems faced will also become more complex. During the exploration and construction of deep strata, especially when encountering high-confined water strata, it will pose a huge challenge to the smooth progress of drilling work. High-confined water strata are different from strata such as perched water and phreatic water. The former exhibits characteristics of high water pressure and large water volume, and the water head height is mostly unknown.

[0003] Therefore, during the drilling exploration of high-confined water strata, phenomena such as a large amount of water gushing, water spraying, casing out of control, and borehole wall collapse are likely to occur, affecting the smooth progress of drilling core sampling and strata lithology analysis work, not only causing waste of financial and material resources, but also having an adverse impact on the smooth progress of subsequent project construction.

[0004] In addition, at the exploration construction site, the mud specific gravity is often adjusted based on experience according to the circulating mud or water gushing situation of the borehole. It takes a certain amount of time for the mud in a deeper borehole to return from the bottom to the top of the borehole, which makes the judgment have a certain lag. When drilling in high-confined water strata, this lag may miss the best opportunity to adjust the mud specific gravity, thereby affecting the effect of drilling core sampling.

[0005] After the core sampling of the borehole in the high-confined water strata is completed, due to the unknown relative height between the water head of the confined aquifer and the opening position of the borehole, and the difficulty of core sampling in the high-confined water strata, if the problem of ensuring the long-term stability of the borehole after core sampling is ignored, as time goes by, the confined water gradually seeps out, resulting in a gradual decrease in the borehole stability, and then leading to borehole collapse.

[0006] Therefore, it is necessary to develop a core sampling device and method that can ensure the progress of core sampling in high-confined water strata and maintain the long-term stability of the borehole after core sampling. Summary of the Invention

[0007] The first object of the present invention is to provide a core sampling device for high-confined water strata, improve the quality of the borehole, ensure the progress of core sampling in high-confined water strata, maintain the long-term stability of the borehole after core sampling, and reduce the occurrence of disasters.

[0008] The second object of the present invention is to provide a core sampling method for a core sampling device when used in a high-confined water formation. This method is applied in geological drilling core sampling fields such as water conservancy and hydropower projects, mining, hydrogeological monitoring, etc., where the formation at the designed depth of the borehole has relatively high confined water. It can improve the hole-forming quality during the borehole core sampling stage and reduce the occurrence of borehole collapse and damaged holes; solve the problems of a large amount of water gushing easily occurring during the core sampling process in a high-confined water formation, resulting in serious spalling, collapse, and damaged holes of the borehole wall.

[0009] In order to achieve the first object of the present invention, the technical solution of the present invention is: A core sampling device for a high-confined water formation, characterized in that: it includes a casing structure, a casing joint, and a structure for preventing water gushing from the drill pipe;

[0010] Multiple casing structures are longitudinally connected through casing joints;

[0011] The drill pipe passes through the casing structure and the casing joint from top to bottom, and the lower end is connected to the structure for preventing water gushing from the drill pipe;

[0012] The structure for preventing water gushing from the drill pipe is located above the core barrel;

[0013] A mud inlet hole and a drainage hole are provided on the structure for preventing water gushing from the drill pipe; the mud inlet hole is vertically arranged and communicated with the core barrel; the drainage hole is horizontally arranged and communicated with the core barrel;

[0014] A one-way valve for the mud hole is located at the lower end of the mud inlet hole and at the connection between the mud inlet hole and the core barrel;

[0015] A one-way valve for the water outlet hole is arranged at the outlet end of the drainage hole and on the side wall of the structure for preventing water gushing from the drill pipe;

[0016] A water pressure sensor is arranged at the outlet end of the drainage hole and inside the one-way valve for the water outlet hole.

[0017] In the above technical solution, an external thread is provided at the connection at the upper end of the casing structure, and an internal thread is provided at the connection at the lower end;

[0018] A waterproof strip is located inside the casing structure and is arranged inside the connections at the upper and lower ends of the casing structure;

[0019] A support device is arranged on the outer side wall of the casing structure.

[0020] In the above technical solution, the included angle α between the support device and the casing structure is less than 0 degrees;

[0021] There are multiple support devices; multiple support devices are arranged at intervals on the outer side wall of the casing structure.

[0022] In the above technical solution, the inner diameters of multiple casing structures decrease sequentially from top to bottom.

[0023] In the above technical solution, the casing joint is a hollow stepped pipe structure with openings at both the upper and lower ends;

[0024] The inner diameter of the upper joint of the casing joint is larger than that of the lower joint;

[0025] External threads are provided at the upper joint opening of the casing joint, and internal threads are provided at the lower joint opening;

[0026] The rubber strip is located inside the casing joint and is respectively located inside the upper and lower joint openings of the casing joint;

[0027] The drill pipe joint is located inside the casing joint and at the connection between the upper joint and the lower joint of the casing joint.

[0028] In order to achieve the second object of the present invention, the technical solution of the present invention is as follows: The coring method of the coring device for high-confined water strata is characterized in that it includes the following steps.

[0029] Step 1: Determine the drilling opening position and orientation;

[0030] According to the geological exploration requirements, conduct preliminary leveling treatment on the drilling site, use instruments such as total station to measure and set the drilling orientation, and arrange a total of 3 observation points at the drilling hole position and the extension line direction to facilitate subsequent installation, debugging, measurement and operation of the drilling rig by workers;

[0031] Step 2: Install and fix the drilling rig;

[0032] After determining the drilling opening position and orientation, install and fix the drilling rig: First, excavate the foundation trench of the drilling rig base. After the excavation of the foundation trench is completed and it is measured and checked to be correct with the designed foundation trench size, pour the concrete of the drilling rig base; Considering the need to strengthen the fixation of the drilling rig in high-confined water strata, use anchor bolts to pre-bury the drilling rig anchor bolts (such as 12 bolts) and fix them on the steel plate; To ensure the accuracy of the position of the pre-buried bolts, install and fix the made pre-buried bolts on the wooden formwork frame and put them into the foundation trench as a whole for pouring, and control the flatness during the pouring process of the base through a spirit level; After the base is poured and left to set for 24 hours, install the drilling rig and adjust the drilling angle by adjusting the angle of the rotary table;

[0033] Step 3: Determine the excavation of the foundation trench for pre-burying the drilling tools;

[0034] Connect the short drilling tool for opening the hole to the kelly bar, find and mark the specific position of opening the hole; Remove the drilling tool for opening the hole, move the drilling rig backward, and excavate the foundation trench for the drilling tool;

[0035] Step 4: Pour the drilling tool into the foundation trench;

[0036] Pour the drilling tool for opening the hole into the foundation trench with concrete. During the concrete pouring process, avoid hitting the drilling tool for opening the hole;

[0037] Step Five: Core Drilling

[0038] After the concrete has finally set, core drilling is carried out. To ensure the smooth progress of core drilling in high-confined water strata, a casing program is adopted during core drilling to enhance the stability of the borehole wall. In response to the changes in the underground confined water layer, a multi-opening casing method can be adopted for core drilling. Casings of different diameters are connected through designed joints, and the casing interfaces are designed to ensure the sealing performance of the interfaces and reduce the flow rate inside the casing. To prevent the casing from sticking to the pipe wall, the periphery of the casing is designed to ensure the stability of the casing.

[0039] Step Six: Hole Sealing

[0040] After the core drilling of the borehole is completed, aggregates with a certain particle size gradation are used for hole sealing.

[0041] In the above technical solution, to prevent water gushing from the drill pipe, a water gushing prevention device is set at the interface between the drill pipe and the casing.

[0042] A water pressure sensor is installed at the outlet end of the drainage hole. During the drilling process, the mud specific gravity is adjusted in a timely manner according to the changes in water pressure to ensure the stability of the borehole.

[0043] The present invention has the following advantages:

[0044] The present invention discloses a device and method for core drilling in high-confined water strata. This method can better ensure the stability of boreholes in high-confined water (the high confinement is within 0.3 MPa) strata, which is conducive to core drilling. A water pressure sensor is introduced to monitor the water pressure status in real time through the device, and the mud specific gravity is adjusted in a timely manner to ensure a better balance of ground pressure and achieve the effect of protecting the borehole wall. The water pressure status, the adopted mud specific gravity, the drilling effect, etc. are recorded, and a multi-dimensional database is established in combination with the mechanical properties such as the rock strength of the subsequent core. Through machine learning, the approximate relationship between water pressure and mud specific gravity can be predicted (that is, the water pressure during the drilling process is recorded by the water pressure sensor, the mud specific gravity is adjusted according to the drilling effect and recorded; the mechanical parameters of the obtained core are analyzed; the water pressure, mud specific gravity, and mechanical parameters of the core are statistically analyzed to establish a database; the database is analyzed; and the approximate ratio of mud and water pressure during the confined water drilling is predicted in combination with the formation conditions). BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the casing in the present invention.

[0046] Figure 2 It is a schematic diagram of the joint for connecting casings of different diameters in the present invention.

[0047] Figure 3 It is a schematic diagram of the fixation of the drilling rig in the present invention.

[0048] Figure 4 This is the diagram of the device for preventing water gushing from drill pipes in the present invention.

[0049] Figure 5 This is the physical diagram of coring in high-confined water formation in the present invention.

[0050] Figure 6 This is the structural schematic diagram of the present invention.

[0051] In the figure: 1 - casing structure, 1-1 - waterproof strip, 1-2 - support device, 2 - casing joint, 2-1 - drill pipe, 2-1 - rubber strip, 2-2 - drill pipe joint, 3 - drilling rig fixing structure, 3-1 - drilling rig, 3-2 - wooden board, 3-3 - bolt, 3-4 - steel plate, 3-5 - reinforced concrete, 3-6 - formation, 4 - device for preventing water gushing from drill pipes, 4-1 - mud inlet hole, 4-2 - drainage hole, 4-3 - connection between drill pipe and water gushing prevention device, 4-4 - water pressure sensor, 4-5 - one-way valve for water outlet hole, 4-6 - one-way valve for mud hole, A - ground, B - pit for pouring concrete around the casing, 5 - drill pipe, 6 - core barrel. Detailed implementation mode

[0052] The following will describe in detail the implementation of the present invention with reference to the accompanying drawings. However, they do not constitute a limitation to the present invention and are only for illustration purposes. At the same time, the advantages of the present invention will be made clearer and easier to understand through the description.

[0053] Referring to the accompanying drawings, it can be seen that a coring device for high-confined water formation includes a casing structure 1, a casing joint 2, and a structure 4 for preventing water gushing from drill pipes;

[0054] Multiple casing structures 1 are longitudinally connected through casing joints 2;

[0055] The drill pipe 5 passes through the casing structure 1 and the casing joint 2 from top to bottom, and the lower end is connected to the structure 4 for preventing water gushing from drill pipes;

[0056] The structure 4 for preventing water gushing from drill pipes is located above the core barrel 6;

[0057] The structure 4 for preventing water gushing from drill pipes is provided with a mud inlet hole 4-1 and a drainage hole 4-2; the mud inlet hole 4-1 is vertically arranged and communicated with the core barrel; the drainage hole 4-2 is horizontally arranged and communicated with the core barrel;

[0058] The one-way valve 4-6 for mud hole is located at the lower end of the mud inlet hole 4-1 and at the connection between the mud inlet hole 4-1 and the core barrel 6;

[0059] The one-way valve 4-5 for water outlet hole is arranged at the outlet end of the drainage hole 4-2 and on the side wall of the structure 4 for preventing water gushing from drill pipes;

[0060] The water pressure sensor 4-4 is arranged at the outlet end of the drain hole 4-2 and inside the one-way valve 4-5 of the water outlet hole.

[0061] Furthermore, external threads are provided at the connection of the upper end of the sleeve structure 1, and internal threads 1-6 are provided at the connection of the lower end;

[0062] The waterproof strip 1-1 is located inside the sleeve structure 1 and on the inner sides of the upper and lower connections of the sleeve structure 1;

[0063] The support device 1-2 is arranged on the outer side wall of the sleeve structure 1.

[0064] Furthermore, the included angle α between the support device 1-2 and the sleeve structure 1 is less than 90 degrees;

[0065] There are multiple support devices 1-2; the multiple support devices 1-2 are arranged at intervals on the outer side wall of the sleeve structure 1.

[0066] Furthermore, the inner diameters of the multiple sleeve structures 1 decrease sequentially from top to bottom.

[0067] Furthermore, the casing joint 2 is a hollow stepped tube structure with openings at both the upper and lower ends;

[0068] The inner diameter of the upper joint of the casing joint 2 is larger than that of the lower joint;

[0069] External threads are provided at the upper joint opening of the casing joint 2, and internal threads are provided at the lower joint opening;

[0070] The rubber strip 2-1 is located inside the casing joint 2 and on the inner sides of the upper and lower joint openings of the casing joint 2 respectively;

[0071] The drill pipe joint 2-2 is located inside the casing joint 2 and at the connection between the upper joint and the lower joint of the casing joint 2.

[0072] Referring to the attached drawings, it can be seen that: in the order of operation, the coring method of the coring device of the present invention for high-confined water formations includes Step 1: determining the drilling position and orientation; Step 2: excavating the foundation trench of the base of the drilling rig 3-1, fixing the drilling rig to the steel plate 3-4 with bolts 3-3, and pouring reinforced concrete 3-5 to fixedly install the drilling rig 3-1; Step 3: determining the trench for excavating and embedding the drilling tool; Step 4: pouring the drilling tool into the trench; Step 5: drilling and coring; Step 6: sealing the hole.

[0073] Specifically as follows:

[0074] Step 1: Determine the drilling opening position and orientation;

[0075] According to the requirements of geological exploration, the drilling site is preliminarily leveled. Total station and other instruments are used to measure and set the azimuth of the drill hole, and 3 observation points are arranged in the direction of the drill hole position and its extension line to facilitate the subsequent installation, debugging, measurement and operation of the drill by workers;

[0076] Step 2: Installation and fixation of the drill;

[0077] After determining the opening position and azimuth of the drill hole, the drill needs to be installed and fixed. First, excavate the foundation trench of the drill base 3-1. After the excavation of the foundation trench is completed and it is measured and checked that the size is correct as designed, considering the need to strengthen the fixation of the drill in the high-confined water formation, anchor bolts 3-3 (such as 12 bolts) are pre-buried for the drill anchor feet and fixed on the steel plate 3-4, and then concrete is poured. To ensure the accuracy of the position of the pre-buried screw rod, the made pre-buried screw rod is installed and fixed on the wooden formwork frame (i.e., the wooden board 3-2), and the whole is put into the foundation trench for pouring, and the flatness during the pouring of the foundation is controlled by a spirit level. After the foundation is poured and left to set for 24 hours, the drill is installed;

[0078] Step 3: Determine the foundation trench for excavating and pre-burying the drill tool;

[0079] Connect the short drill tool for opening the hole to the drill pipe, find and mark the specific position of opening the hole. Remove the drill tool for opening the hole, move the drill backward, and excavate the foundation trench for the drill tool;

[0080] Step 4: Pour the drill tool into the foundation trench;

[0081] Pour the drill tool for opening the hole into the foundation trench with concrete. During the concrete pouring process, avoid hitting the drill tool for opening the hole;

[0082] Step 5: Core drilling.

[0083] Specifically explain the method for the present invention to achieve core drilling in the high-confined water formation in combination with the legend. After the drill is fixedly installed and the drill tool is poured into the foundation trench, drilling is carried out with a diameter of φ220mm, and the Figure 1 casing is lowered. To prevent the casing from clinging to the borehole wall, a certain number of support devices 1-2 are designed on the outer wall of the casing. One is to prevent the casing from clinging to the pipe wall, which is not conducive to mud circulation. The second is to correct the casing to prevent inclination. The third is to increase the resistance to prevent the casing from bulging due to water pressure. During the drilling process, the drill pipe passes through the Figure 4 designed device for preventing water from gushing out of the drill pipe to reduce the situation of confined water gushing out from the drill pipe. The drill pipe 4-1 and the core barrel 4-8 are connected through the designed device 4 for preventing water from gushing out of the drill pipe. During the drilling process, the mud enters the core barrel through the vertical mud inlet hole 4-1 and relies on the pressure to open the one-way valve 4-6 of the mud hole. When the confined water increases, the water will be discharged along the horizontal drain hole 4-2 through the one-way valve 4-5 of the water outlet hole, reducing the occurrence of the event of water gushing out of the drill pipe.

[0084] In addition, a water pressure sensor 4-4 is fixed at the drainage hole. When the water pressure increases, measures such as adding barite powder can be taken to increase the specific gravity of the mud and improve the viscosity of the mud, ensuring better balance of the ground pressure and achieving the effect of protecting the wall. During the drilling process, multi-opening drilling is adopted. For the second opening, drilling is carried out with a diameter of φ159mm, and a casing is lowered. Figure 2 The drill pipe joint 2 of the intermediate casing joint device is used to connect two casings with different diameters by rotating the drill pipe. Rubber strips 2-1 (including the first rubber strip and the second rubber strip) are designed at the casing threads, which can ensure good sealing at the joint.

[0085] Step Six: Sealing the Hole

[0086] After the core drilling is completed, the casing is retained in the borehole. First, a certain gradation of coarse aggregate is used to seal the hole to reduce the water pressure of the confined water, ensuring that the stone filling exceeds the top of the confined water layer by more than 5 meters. A pit B with a depth of 1 meter and a diameter of about 1 meter around the casing is excavated for pouring concrete, preventing the confined water from pushing the casing out, and concrete is poured into the casing to ensure good sealing and water blocking effect.

[0087] Other parts not described belong to the prior art.

Claims

1. Core sampling method for a core sampling device used in high-confined water strata, characterized in that: Comprising a coring device for high-confined water formations, the coring device for high-confined water formations includes a casing structure (1), a casing joint (2), and a structure (4) for preventing water gushing from the drill pipe; Multiple casing structures (1) are longitudinally connected through casing joints (2); The drill pipe (5) passes through the casing structure (1) and the casing joint (2) from top to bottom, and the lower end is connected to the structure (4) for preventing water gushing from the drill pipe; The structure (4) for preventing water gushing from the drill pipe is located above the core barrel (6); The structure (4) for preventing water gushing from the drill pipe is provided with a mud inlet hole (4-1) and a drainage hole (4-2); the mud inlet hole (4-1) is vertically arranged and communicated with the core barrel; the drainage hole (4-2) is horizontally arranged and communicated with the core barrel; The mud hole one-way valve (4-6) is located at the lower end of the mud inlet hole (4-1) and at the connection between the mud inlet hole (4-1) and the core barrel; The water outlet hole one-way valve (4-5) is arranged at the outlet end of the drainage hole (4-2) and on the side wall of the structure (4) for preventing water gushing from the drill pipe; The water pressure sensor (4-4) is arranged at the outlet end of the drainage hole (4-2) and inside the water outlet hole one-way valve (4-5); The connection at the upper end of the casing structure (1) is provided with an external thread, and the connection at the lower end is provided with an internal thread (1-6); The waterproof strip (1-1) is located inside the casing structure (1) and on the inner sides of the upper and lower connections of the casing structure (1); The support device (1-2) is arranged on the outer side wall of the casing structure (1); The method includes the following steps, Step 1: Determine the opening position and orientation of the borehole; According to the requirements of geological exploration, conduct preliminary leveling treatment on the borehole site, use a total station to measure and set the borehole orientation, and arrange 3 observation points in the borehole position and the extension line direction to facilitate subsequent installation, debugging, measurement, and operation of the drilling rig by workers; Step 2: Install and fix the drilling rig; After determining the opening position and orientation of the borehole, install and fix the drilling rig: First, excavate the foundation trench for the drilling rig. After the excavation of the foundation trench is completed and the dimensions are checked and found to be correct according to the design foundation trench dimensions, pour the concrete for the drilling rig foundation; use anchor bolts to embed the drill rig anchor bolts and fix them on the steel plate; install and fix the fabricated embedded bolts on the wooden formwork frame and put them into the foundation trench as a whole for pouring, and control the flatness during the pouring process of the foundation by a spirit level; install the drilling rig 24 hours after the foundation is poured and set, and adjust the borehole angle by adjusting the angle of the rotary table; Step 3: Determine the foundation trench for excavating and embedding the drilling tools; Connect the short drilling tool for opening the hole to the kelly bar, find and mark the specific position of opening the hole; remove the drilling tool for opening the hole, move the drilling rig backward, and excavate the foundation trench for the drilling tool; Step 4: Pour the drilling tool into the foundation trench; Pour the drilling tool for opening the hole into the foundation trench with concrete. During the concrete pouring process, avoid hitting the drilling tool for opening the hole; Step 5: Drill and core; After the concrete has finally set, core samples are drilled. During core sampling, a casing procedure is adopted to enhance the stability of the hole wall. In response to the changes in the underground confined aquifer, a multi-stage casing method is used for drilling and core sampling. Casing pipes of different diameters are connected through designed joints, and the interfaces of the casing pipes are designed to ensure the sealing performance of the interfaces and reduce the flow rate inside the casing pipes. To prevent the casing pipes from clinging to the pipe wall, the periphery of the casing pipes is designed to ensure the stability of the casing pipes. Step Six: Sealing the hole; After the drilling and core sampling are completed, aggregates with a certain particle size gradation are used to seal the hole.

2. The coring method of the coring device for high-confined water formation according to claim 1, wherein: The included angle α between the support device (1-2) and the casing structure (1) is less than 90 degrees; There are multiple support devices (1-2); the multiple support devices (1-2) are arranged at intervals on the outer side wall of the casing structure (1).

3. The coring method of the coring device for high-confined water formation according to claim 2, characterized in that: The inner diameters of the multiple casing structures (1) decrease sequentially from top to bottom.

4. The coring method of the coring device for high-confined water formation according to claim 3, characterized in that: The casing joint (2) is a hollow stepped pipe structure with openings at both the upper and lower ends; The inner diameter of the upper joint of the casing joint (2) is larger than that of the lower joint; External threads are provided at the upper joint opening of the casing joint (2), and internal threads are provided at the lower joint opening; The rubber strip (2-1) is located inside the casing joint (2) and is respectively located inside the upper and lower joint openings of the casing joint (2); The drill pipe joint (2-2) is located inside the casing joint (2) and at the connection between the upper joint and the lower joint of the casing joint (2).

5. The coring method of the coring device for high-confined water formation according to claim 4, characterized in that: In Step Five, a water gushing prevention structure (4) is provided at the interface between the drill pipe and the casing; A water pressure sensor (4-4) is provided at the outlet end of the drainage hole (4-2). During the drilling process, the mud specific gravity is adjusted in a timely manner according to the changes in water pressure to ensure the stability of the drill hole.

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