Core tube that can be used to clean holes, retrieve gravel and take cores

Abstract

The invention discloses a core tube that can be used for hole cleaning, sand and gravel scooping and core extraction, including a sand scooping section, a core extraction section and a core tube connection section; the sand scooping section is provided with an inner cavity tube wall to form a double-layer structure; the upper end of the inner cavity tube wall is connected to the core tube joint; the top of the sand scooping section is in an arc-shaped streamline; the outer layer tube wall near the upper end of the sand scooping section is provided with a pair of sand inlets; the sand scooping section is provided with a plurality of drainage holes near the lower end; the upper part of the core tube connection section is provided with an inner cavity tube wall to form a double-layer structure, and the lower part is a single-layer structure; the middle part of the core tube connection section is provided with an annular sand isolation plate to form a step-shaped structure; the gap between the double-layer structures of the sand scooping section and the gap between the double-layer structures at the upper part of the core tube connection section and the sand isolation plate form a sand storage chamber with an upper opening; the lower end of the core tube connection section is connected to the core extraction section, and the lower end of the core extraction section is provided with a drill bit. In addition to the function of drilling and coring, the invention also has the function of scooping sand and gravel from various sand and gravel and weathered rock debris layers.

Description

Technical Field

[0001] The invention relates to the technical field of geological drilling, in particular to a core tube which can be used for cleaning holes, scooping out sand and gravel, and taking cores. Background Art

[0002] In geotechnical engineering investigation, medium-coarse sand and gravel, sand and gravel containing clay, and weathered rock debris layers are often encountered. In these soil layers, during the rotary drilling and hole cleaning process of the mud-walled core tube, coarse particles such as medium-coarse sand and gravel, weathered rock debris, etc. often cannot be returned to the borehole mouth with the circulating mud and discharged, resulting in an increase in sediment in the hole, incomplete hole cleaning, and most of the core samples taken by the core tube are disturbed sediments, resulting in the collection of fresh core samples. Very few, which affects the accurate division of the stratigraphic positions and also affects the accuracy and reliability of the in-situ test data (standard penetration test and heavy dynamic penetration test) of these coarse-grained soil layers. For some soil layers, in-situ test data (standard penetration test and heavy dynamic penetration test) are crucial for geotechnical engineers to master the engineering mechanical properties of these soil layers. This issue directly affects the quality of exploration results in these areas and the accuracy and reliability of geotechnical design parameters. At present, conventional exploration processes and equipment are often difficult to solve this problem. Using the existing special sand bailer, it is necessary to first use mud wall rotary drilling to clean the hole and bailed out the sand, then lift the drill, and then lower the core tube to drill and coring. This adds one round, which is time-consuming and labor-intensive, and increases the risks of hole collapse, drill jamming and drill burial. In existing practical use, ideal results are often not achieved.

[0003] There are several commonly used sand bailing equipment solutions for drilling and cleaning holes in the prior art:

[0004] A Chinese invention patent with publication number CN 103573202 A discloses a drilling sand bailing mechanism and a drilling tool. The sand bailing mechanism is arranged outside a drill pipe, and includes a sand bailing tube arranged outside the drill pipe and axially arranged along the drill pipe. The sand bailing tube includes a closed end connected to the drill pipe and an annular side wall arranged outside the drill pipe and having a gap with the drill pipe to form a sand filling space. The upper end of the side wall has an inclined opening connected to the sand filling space. The side wall is respectively provided with a plurality of sand inlet holes and water outlet holes connected to the sand filling space. Along the drill pipe from top to bottom, the plurality of sand inlet holes are respectively placed above the plurality of water outlet holes.

[0005] The Chinese utility model patent with publication number CN 207048709 U discloses a reverse circulation drilling sand bailer, which is connected to the part of the reverse circulation drilling tool structure close to the drill bit, with the lower part connected to the drill collar or the drill bit, and the upper part connected to the single-wall drilling tool, becoming a part of the reverse circulation drilling tool, and has the functions of sand settling, sand bailing and anti-blocking.

[0006] The Chinese utility model patent with publication number CN 204492724 U discloses a sand bailing device, comprising a milling shoe, a drill bit, a mandrel, a spiral blade and a sand storage barrel, wherein the milling shoe is connected to the sand storage barrel, the drill bit is fixedly arranged in the milling shoe, the drill bit is fixedly connected to the mandrel, the spiral blade is arranged on the mandrel, and the mandrel and the spiral blade constitute a spiral conveying mechanism for conveying settled sand to the sand storage barrel; the sand bailing problem of low-pressure leaking oil and gas wells is solved.

[0007] The Chinese utility model patent with publication number CN 205876248 U discloses a valve flap type sand bailing barrel, in which the negative pressure valve adopts a valve flap type. Once the settled sand leaks out of the sand bailing barrel body, the valve flap will close along with the leakage of the settled sand.

[0008] Through the analysis of the above four schemes, it can be seen that: although the invention patent with publication number CN 103573202 A is mainly aimed at geotechnical engineering investigation and geological exploration, the drill is easily buried or stuck due to the transverse inclined opening of the sand bailing tube, and there are gaps between the sand bailing tubes and between the sand bailing tubes and the core tube, which makes it easy for large-grained gravel or rock debris to settle in the gaps and cause the equipment to get stuck, and it is more likely to bury the drill, which has great limitations and construction risks in actual use; the utility model patent with publication number CN207048709 U is mainly used for sand settling, sand bailing and anti-blocking in drilling, which is achieved by reverse circulation while drilling, while drilling in geotechnical engineering investigation generally adopts positive circulation; the utility model patent with publication number CN 204492724 U is used to deal with the sand bailing problem of lost oil and gas wells in oil fields, does not return slurry, and does not have the function of drilling and forming holes; the utility model patent with publication number CN205876248 The utility model patent of U is to solve the problem of sand settling in the wellbore and sand burial of downhole tools in oil wells, and does not have the function of drilling and forming holes.

[0009] In addition, other invention or utility model patents not listed are basically for sand dredging in oil field production wells, which are not suitable or practical in geotechnical engineering surveys and geological surveys. Summary of the invention

[0010] In view of the above-mentioned defects of the prior art, the present invention provides a core tube that can both clean the hole and retrieve sand and gravel and take cores. The purpose achieved is that in addition to the conventional core tube drilling and coring functions, it also has the function of catching sand and gravel and rock debris during the drilling process of medium-coarse sand and gravel, sand and gravel containing clay soil and weathered rock debris layers, thereby playing a more thorough hole cleaning effect, which greatly solves the problem that the coarse-grained sand and gravel and rock debris caused by the current conventional drilling process in drilling in medium-coarse sand and gravel, sand and gravel containing clay soil and weathered rock debris layers cannot be returned with the mud circulation due to their high specific gravity, resulting in thick sediment, making it difficult to collect fresh core samples, affecting the accurate division of soil layer boundaries and the accuracy and reliability of in-situ test data.

[0011] To achieve the above purpose, the present invention discloses a core tube which can be used for both hole cleaning and gravel extraction as well as core extraction. The upper end of the core tube is connected to a drill pipe female joint through a core tube joint, and the lower end is connected to a drill bit; the upper end of the drill pipe female joint is connected to the drill pipe.

[0012] Wherein, the core pipe comprises a sand bailing section, a coring section, and a core pipe connecting section connecting the sand bailing section and the coring section;

[0013] The sand dredging section is provided with an inner cavity tube wall to form a double-layer structure; the upper end of the inner cavity tube wall is connected to the core tube joint;

[0014] The outer tube wall of the sand bailing section near the upper end is symmetrically provided with a pair of sand inlets extending along the length direction; the outer tube wall of the sand bailing section near the lower end is provided with a plurality of drainage holes;

[0015] The outer diameter of the core pipe connecting section is the same as the outer diameter of the sand bailing section and the outer diameter of the coring section, the upper part is provided with an inner cavity wall to form a double-layer structure, and the lower part is a single-layer structure;

[0016] An annular sand-isolating plate is provided in the middle of the core tube connection section to form a step-shaped structure; the outer diameter of the sand-isolating plate matches the outer tube wall of the sand-bailing section and the outer tube wall of the upper part of the core tube connection section; the inner diameter of the sand-isolating plate matches the inner tube wall of the sand-bailing section and the inner tube wall of the upper part of the core tube connection section;

[0017] The gap between the double-layer structures of the sand bailing section and the gap between the double-layer structures at the upper part of the core pipe connecting section and the sand isolation plate form a sand storage chamber with an upper side opening;

[0018] The lower end of the core tube connecting section is connected to the coring section, and the lower end of the coring section is provided with the drill bit.

[0019] Preferably, the plurality of drainage holes are provided in at least three layers along the length direction of the sand bailing section, and the plurality of drainage holes in each layer are evenly distributed around the axis of the sand bailing section.

[0020] Preferably, the upper and lower ends of the core tube connecting section are respectively connected to the sand bailing section and the coring section by threaded connection, the inner cavity wall of the core tube connecting section is connected to the inner cavity wall of the sand bailing section by step-shaped plug-in, and the lower part of the core tube coring section can be threadedly connected to the drill bit.

[0021] More preferably, the threaded connection is a flat thread.

[0022] Preferably, the core tube is 4.3m long; the sand bailing section is 2.0m long; the core tube connecting section is 20cm long; the coring section is 2.0m long; the size of each sand inlet is 30mm*300mm; the size of the inner cavity tube wall is 20mm in inner diameter and 3mm in wall thickness; the sand storage chamber is a cylindrical structure with a width of 36mm and a length of 1.7m.

[0023] Beneficial effects of the present invention:

[0024] The present invention can not only perform rotary drilling with mud wall protection, but also the novel arc-shaped streamline at the top of the core tube sand bailing section can effectively avoid accidents of drill bit sticking or drill bit burying when colliding with the hole wall when bailing sand, gravel or weathered rock debris, and can also perform rotary drilling to take core samples without sending flushing fluid after the hole is cleaned.

[0025] After the sand bailing section on the core tube of the present invention is filled with gravel or rock debris, if it is stuck or blocked, the sand bailing section on the core tube only needs to be lifted, and the coarse sediment can be conveniently poured out by gently shaking or tapping with a hammer, thereby achieving the purpose of clean, thorough and convenient hole cleaning. At the same time, the coring section at the lower part of the core tube directly takes core samples, thereby improving the exploration efficiency and laying a solid foundation for the accuracy and reliability of in-situ test data. The present invention will have broad prospects in geotechnical engineering investigation and geological exploration.

[0026] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of an embodiment of the present invention is shown.

[0028] Figure 2 Showing the present invention Figure 1 Schematic diagram of the cross-sectional structure at AA in the middle.

[0029] Figure 3 Showing the present invention Figure 1 Schematic diagram of the cross-sectional structure at BB in the middle.

[0030] Figure 4 Showing the present invention Figure 1 Schematic diagram of the cross-sectional structure of the sand barrier at CC.

[0031] Figure 5 A schematic diagram of the enlarged structure of the lower portion of the sand bailing section and the connecting section of the core tube in one embodiment of the present invention is shown.

[0032] Figure 6 A schematic diagram of a structure of an embodiment of the present invention disposed in a borehole is shown. DETAILED DESCRIPTION

[0033] like Figures 1 to 6 As shown, a core tube is disposed in the borehole 11 for both cleaning the hole and scooping out gravel and core extraction. The outer diameter of the core tube is smaller than the borehole 11, forming a gap 12.

[0034] The upper end of the core tube is connected to the drill pipe female joint 2 through the core tube joint 3, and the lower end is connected to the drill bit 10; the upper end of the drill pipe female joint 2 is connected to the drill pipe 1.

[0035] The core pipe includes a sand bailing section 4, a coring section 9, and a core pipe connecting section 8 connecting the sand bailing section 4 and the coring section 9;

[0036] An inner cavity wall is provided in the sand bailing section 4 to form a double-layer structure; the upper end of the inner cavity wall is connected to the core pipe joint 3;

[0037] The outer tube wall near the upper end of the sand bailing section 4 is symmetrically provided with a pair of sand inlets 5 extending along the length direction; the outer tube wall near the lower end of the sand bailing section 4 is provided with a plurality of drainage holes 7;

[0038] The outer diameter of the core pipe connecting section 8 is the same as that of the sand bailing section 4 and the coring section 9. The upper part is provided with an inner cavity wall to form a double-layer structure, and the lower part is a single-layer structure.

[0039] An annular sand-isolating plate is provided in the middle of the core tube connection section 8 to form a step-shaped structure; the outer diameter of the sand-isolating plate matches the outer tube wall of the sand-bailing section 4 and the outer tube wall of the upper portion of the core tube connection section 8; the inner diameter of the sand-isolating plate matches the inner tube wall of the sand-bailing section 4 and the inner tube wall of the upper portion of the core tube connection section 8;

[0040] The gap between the double-layer structures of the sand bailing section 4 and the gap between the double-layer structures at the upper part of the core pipe connecting section 8 and the sand isolation plate form a sand storage chamber 6 with an upper side opening;

[0041] The lower end of the core tube connecting section 8 is connected to the coring section 9 , and the lower end of the coring section 9 is provided with a drill bit 10 .

[0042] The principle of the present invention is:

[0043] The core tube connecting section 8 seamlessly connects the sand bailing section 4 and the coring section 9 of the core tube, and forms a closed sand storage chamber 6 in the upper sand bailing section of the core tube, and the flushing liquid in the sand storage chamber 6 is discharged through a plurality of drainage holes 7.

[0044] The coring section 9 is similar to a conventional core tube and is seamlessly connected to the sand bailing section 4 via the core tube connecting section 8 .

[0045] The present invention can clean the hole to obtain sand and gravel and can also take cores. Figure 6As shown, during the drilling process, through the mud wall rotary drilling, the flushing fluid carrying suspended sand, gravel or weathered rock debris returns through the sand inlet 5 of the sand bailing section 4 into the sand storage chamber 6 in the gap 12 between the borehole 11 and the core tube, and the flushing fluid is discharged through the drainage hole 7 to achieve the purpose of cleaning the hole and bailing sand; the core tube seamlessly connected at the bottom can achieve the purpose of directly taking core samples.

[0046] After the core tube is taken out from the borehole 11, the core sample is first pushed out by water pressure or shaken, and the core sample is taken out from the core tube by a light hammer and placed in the core box. Then, the sand bailing section 4, the coring section 9 and the core tube connecting section 8 are conveniently disassembled by chain pliers, and the sand bailing section 4 is lifted, so that the bailed sand, gravel, weathered rock debris, etc. will fall freely. If there is a blockage, the coarse sediment can be easily poured out by gently shaking or tapping with a hammer.

[0047] In some embodiments, the plurality of drainage holes 7 are provided in at least three layers along the length direction of the sand bailing section 4 , and the plurality of drainage holes 7 in each layer are evenly distributed around the axis of the sand bailing section 4 .

[0048] In some embodiments, the upper and lower ends of the core tube connecting section 8 are respectively connected to the sand bailing section 4 and the coring section 9 by threaded connection, the inner cavity wall of the core tube connecting section 8 is connected to the inner cavity wall of the sand bailing section 4 by step-shaped plug-in, and the lower part of the core tube coring section 9 can be threadedly connected to the drill bit 10.

[0049] In some embodiments, the threaded connection is a flat thread.

[0050] In some embodiments, the core tube is 4.3m long; the sand bailing section 4 is 2.0m long; the core tube connecting section 8 is 20cm long; the coring section 9 is 2.0m long; the size of each sand inlet 5 is 30mm*300mm; the size of the inner cavity wall is 20mm in diameter and 3mm in thickness; the sand storage chamber 6 is a cylindrical structure with a width of 36mm and a length of 1.7m.

[0051] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A core tube that can be used for both hole cleaning and gravel extraction and core extraction, wherein the upper end of the core tube is connected to a drill pipe female joint (2) via a core tube joint (3), and the lower end is connected to a drill bit (10); the upper end of the drill pipe female joint (2) is connected to a drill pipe (1); the characteristics are: The core pipe comprises a sand bailing section (4), a coring section (9), and a core pipe connecting section (8) connecting the sand bailing section (4) and the coring section (9); The sand bailing section (4) is provided with an inner cavity tube wall to form a double-layer structure; the upper end of the inner cavity tube wall is connected to the core pipe joint (3); the top of the sand bailing section (4) is in the shape of an arc-shaped streamline; The outer tube wall of the sand bailing section (4) near the upper end is symmetrically provided with a pair of sand inlets (5) extending in the length direction; the outer tube wall of the sand bailing section (4) near the lower end is provided with a plurality of drainage holes (7); The outer diameter of the core tube connecting section (8) is the same as the outer diameter of the sand bailing section (4) and the outer diameter of the coring section (9); the upper part of the core tube connecting section (8) is provided with an inner cavity wall to form a double-layer structure, and the lower part is a single-layer structure; An annular sand barrier is provided in the middle of the core tube connection section (8) to form a step-shaped structure; the outer diameter of the sand barrier matches the outer tube wall of the sand bailing section (4) and the outer tube wall of the upper part of the core tube connection section (8); the inner diameter of the sand barrier matches the inner tube wall of the sand bailing section (4) and the inner tube wall of the upper part of the core tube connection section (8); The gap between the double-layer structures of the sand bailing section (4) and the gap between the double-layer structures at the upper part of the core tube connecting section (8) together with the sand isolation plate form a sand storage chamber (6) with an upper side opening; The lower end of the core tube connecting section (8) is connected to the coring section (9), and the lower end of the coring section (9) is provided with the drill bit (10); The upper and lower ends of the core tube connecting section (8) are respectively connected to the sand bailing section (4) and the coring section (9) by means of threaded connection, the inner cavity wall of the core tube connecting section (8) is connected to the inner cavity wall of the sand bailing section (4) by means of step-shaped plug-in, and the lower part of the core tube coring section (9) is threadedly connected to the drill bit (10); The dimensions of the inner cavity wall are 20 mm in inner diameter and 3 mm in wall thickness; the sand storage chamber (6) is a cylindrical structure with a width of 36 mm and a length of 1.7 m; After the core tube is taken out of the borehole (11), the core sample is first pushed out by water pressure or taken out of the core tube by shaking or light hammering and placed in a core box. Then, the sand bailing section (4), the coring section (9) and the core tube connecting section (8) are disassembled by chain clamps, and the sand bailing section (4) is lifted. The sand, gravel and weathered rock debris bailed out will fall freely. If there is any blockage, the coarse sediment bailed out will be poured out by shaking or light hammering.

2. The core tube capable of both cleaning the hole and scooping out gravel and core extraction according to claim 1 is characterized in that: The plurality of drainage holes (7) are arranged in at least three layers along the length direction of the sand bailing section (4), and the plurality of drainage holes (7) in each layer are evenly distributed around the axis of the sand bailing section (4).

3. The core barrel capable of both cleaning the hole and scooping out gravel and core extraction according to claim 1 is characterized in that: The thread connection method is a flat thread.

4. The core tube capable of both cleaning the hole and scooping out gravel and core extraction according to claim 1 is characterized in that: The core tube is 4.3 m long; the sand bailing section (4) is 2.0 m long; the core tube connecting section (8) is 20 cm long; and the coring section (9) is 2.0 m long.

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