Anti-collapse casing tool for stratum drilling exploration

Abstract

The utility model relates to the technical field of drilling construction in the industries of geotechnical engineering, geological engineering, hydrogeological engineering, mine engineering and the like, and discloses an anti-collapse casing tool for stratum drilling exploration, which comprises a casing which is arranged inside a residual rock core outer pipe. The sleeve can only slide downwards relative to the remaining rock core outer pipe and cannot slide upwards. And the residual rock core outer pipe is a rock core outer pipe drilling tool for a double-layer rock core drilling process. A first friction expansive force ring and a second friction expansive force ring are fixedly connected to the outer portion of the sleeve. According to the utility model, the problem that the casing is difficult to run in easily collapsed and necking stratums such as gravel, pebble beds, miscellaneous fill, sludge or muddy soft soil, sand, rock stratums which are easily softened when meeting water, high crustal stress rock stratums and the like can be effectively solved. The construction process is stable and safe, material selection is simple, steps are clear, operation is simple and easy to implement, popularization is easy, and the beneficial effects are obvious.

Description

Technical Field

[0001] The utility model relates to the technical field of drilling construction required in industries such as geotechnical engineering, geological engineering, hydrogeological engineering and mining engineering, and in particular to an anti-collapse casing tool for stratum drilling exploration. Background Art

[0002] Drilling and hole-forming have long been a crucial technical tool in fields such as geotechnical engineering, geological engineering, hydrogeological engineering, and mining engineering. Casing is a crucial tool used to assist in drilling. Inserting casing into a borehole supports and reinforces the borehole wall, ensuring quality during continued drilling and preventing collapse and necking. It also allows for better access to later operations such as sampling, exploration, and grouting after completion. This is particularly true when drilling in rock and soil formations such as gravel, gravel, miscellaneous fill, silt or silty soft soil, sand, water-softening rock formations, and high-stress rock formations. Due to the poor verticality of the rock and soil formations and their susceptibility to collapse and necking, successful casing installation is directly related to the success of the drilling operation. Therefore, successfully installing casing in formations prone to collapse and necking is a technical challenge worthy of research in these industries.

[0003] Currently, there are generally two methods for installing casing in boreholes depending on the drilling process.

[0004] The first method uses a single-layer core barrel drilling process. When the borehole reaches a relatively intact and stable rock or soil layer, the drill string (drill pipe, drill pipe, and drill bit) is used to pressure-wash the hole. Then, all drill string and drilling string are removed, and steel casing is inserted. However, successful installation requires the newly drilled hole wall to be essentially stable, which presents risks. In stable rock and soil, the hole wall is vertical, flat, and unlikely to collapse quickly, making casing installation a problem. However, if abnormalities such as falling blocks, collapse, or necking occur, the casing may become skewed, making verticality impossible. In severe cases, it may become stuck or become blocked, preventing lowering, resulting in a failed installation. In this case, the casing can only be removed and the drill string reinserted to re-drill. Once the hole is repaired, casing can then be reinserted. This is time-consuming and labor-intensive, and can also lead to the risk of deflection, expansion of the collapsed section, and even drilling failure. If the drill string and drilling string cannot be removed, the hole will have to be abandoned.

[0005] The second method involves using a double-layer core barrel drilling process, where the outer core barrel is used as a temporary casing. Once the hole is fully utilized, the drill rig is activated to remove and dismantle the outer core barrel. This method requires the drill rig to wait in place or be relocated later to remove the outer core barrel, which delays the project and consumes additional manpower. Furthermore, the outer core barrel remains buried in the hole for a long time, making it very difficult to remove and potentially damaging. Therefore, this method is highly uneconomical for boreholes that require extended use.

[0006] Therefore, in response to the above-mentioned problems, an anti-collapse casing tool for stratum drilling exploration is now proposed. Utility Model Content

[0007] In order to make up for the above shortcomings, the utility model provides an anti-collapse casing tool for formation drilling exploration, aiming to improve the problem in the existing technology that some devices repair the borehole and then lower the casing, which is time-consuming and labor-intensive, and prone to the risk of deflection and expansion of the collapsed section.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A collapse-proof casing tool for formation drilling exploration includes a casing, wherein the casing is inside a remaining core outer tube, and the casing can only slide downward relative to the remaining core outer tube, and cannot slide upward. The remaining core outer tube is a core outer tube drilling tool for a double-layer core drilling process. The outside of the casing is fixedly connected with a friction expansion ring 1 and a friction expansion ring 2. The friction expansion ring 1 is 20-30 cm downward from the top end of the casing. The spacing between the friction expansion ring 2 and the friction expansion ring 1 is not less than the length of a single section of the remaining core outer tube, and not greater than the length of two single sections of the remaining core outer tube. The outer diameter of the casing is 15-30 mm smaller than the inner diameter of the remaining core outer tube. The total length of the casing is at least one single section longer than the total length of the remaining core outer tube.

[0010] As a further description of the above technical solution:

[0011] The exterior of the remaining core outer tube is in close contact with a readily collapsible or necking formation and a relatively intact formation. The remaining core outer tube is composed of sections, each section being threadedly connected. Before the remaining core outer tube is lifted and removed section by section, the exterior of the remaining core outer tube is in close contact with the entire readily collapsible or necking formation, and the bottom end of the remaining core outer tube extends downward beyond the bottom boundary of the readily collapsible or necking formation and into the relatively intact formation below by at least 30 cm, with the top end of the remaining core outer tube exposed above the ground by at least 20 cm.

[0012] As a further description of the above technical solution:

[0013] The first and second friction expansion rings are identical in size and manufacture. They are made from zigzag-sheared, bent-out iron sheet, wrapped in a braided fabric. The iron sheet is 0.3-0.6mm thick, 20cm wide, and the length of the outer circumference of the sleeve. The braid is approximately 0.1mm thick. The sheared iron sheet is bent outward at an acute angle of less than 30 degrees. Each friction expansion ring is shaped like a trumpet, opening upward.

[0014] As a further description of the above technical solution:

[0015] The downward sliding of the casing relative to the remaining core outer tube is achieved by the hydraulic pressure of the drilling rig power shaft transmitted by a dowel rod, the length of the dowel rod is 20-30 cm longer than the length of a single section of the core outer tube, and the diameter of the dowel rod is consistent with that of the casing.

[0016] The utility model has the following beneficial effects:

[0017] 1. This utility model effectively solves the problem of difficulty in running casing in strata prone to collapse and necking, such as gravel, pebble layers, miscellaneous fill, silt or silty soft soil, sand, water-softened rock formations, and high-stress rock formations. The construction process is reliable and safe, the material selection is simple, the steps are clear, the operation is simple and easy, and it is easy to promote, with significant beneficial effects.

[0018] 2. The utility model cleverly utilizes the advantages of the double-layer core barrel drilling process. Through the installation method of the utility model, the temporary support of the core outer tube for the easily collapsed or necked formation section is gradually replaced by long-term support with casing.

[0019] 3. The present invention can save construction time, manpower and cost. After the drilling rig has finished running the casing, it can be moved to the next drilling operation. There is no need to keep the drilling rig waiting in place or to move the drilling rig again at a later stage to remove the core outer tube.

[0020] 4. The present invention is particularly useful for further reinforcing the casing using grouting. The trumpet-shaped friction expansion ring can form a barrier to the slurry, helping it to retain and solidify quickly. The casing installed with the present invention can significantly extend the service life of the borehole after grouting, achieving significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a three-dimensional schematic diagram of an anti-collapse casing tool for formation drilling exploration proposed by the present invention;

[0022] Figure 2 This is a schematic structural diagram of a force transmission rod of an anti-collapse casing tool for formation drilling exploration proposed by the present invention;

[0023] Figure 3 This is a structural diagram of a casing and a friction expansion ring of an anti-collapse casing tool for formation drilling exploration proposed by the present invention;

[0024] Figure 4 This is a schematic structural diagram of the casing support after all the remaining core outer tubes of an anti-collapse casing tool for formation drilling exploration proposed by the utility model are removed.

[0025] Legend:

[0026] 1. Casing; 2. Outer tube of remaining core; 3. Friction expansion ring 1; 4. Friction expansion ring 2; 5. Formation prone to collapse or necking; 6. Relatively intact formation; 7. Dowel rod. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Reference Figures 1 to 4 The first step is to prepare for casing installation (1). A double-layer core barrel drilling rig is used to drill the hole to the final depth specified by the design, specifications, standards, or technical requirements. This depth generally requires drilling into a relatively stable formation and reaching a sufficient depth. First, the inner core barrel and the core are completely removed. Then, a portion of the outer core barrel is removed, leaving a portion of the outer core barrel such that the bottom of this portion extends at least 30 cm below the bottom edge of the easily collapsible or necking formation 5, and the top of this portion is at least 20 cm above the surface. The remaining portion of the outer core barrel, referred to here as the remaining outer core barrel 2, can be determined based on the thickness of the easily collapsible or necking formation 5 and the length of the core barrel section. At this point, the remaining outer core barrel 2 remaining in the borehole is in close contact with the borehole wall, making it relatively stable and preventing it from falling. The thickness of the easily collapsible or necking formation 5 is still supported by the remaining outer core barrel 2, preventing it from collapsing or necking.

[0029] It should be noted that during the entire process from preparation to installation of the casing 1 , the drilling rig should remain stationary, and the hydraulic power disc spindle of the drilling rig should be used to apply upward rotational power and vertical downward pressure.

[0030] The second step is to select and determine the specifications and dimensions of the sleeve 1 and make the friction expansion ring.

[0031] (1) Specifications and dimensions of casing 1

[0032] The outer diameter of casing 1 should match the inner diameter of the core outer tube. The outer diameter of casing 1 should be 15-30mm smaller than the inner diameter of the core outer tube and the inner diameter of the drill bit. For example, if the core outer tube has an outer diameter of 108mm and an inner diameter of 89mm, casing 4 with an outer diameter of 75mm, 70mm, or 60mm should be selected.

[0033] The total length of the casing 1 is at least one section length longer than the total length of the remaining core outer tube 2. For example, if the length of a single section of the core outer tube is 1.5 m, the total length of the casing 1 is 1.5 m longer than the total length of the remaining core outer tube 2.

[0034] The casing 1 can be lengthened section by section, generally by threaded connection. When the thickness of the easily collapsed or necked soil layer section is not large, the entire casing can be assembled and lowered into the core outer tube together.

[0035] (2) Making friction expansion ring

[0036] Casing 1 is connected to the inner wall of the core outer tube by frictional extrusion, which is generated by friction expansion rings 1 3 and 2 4. The friction expansion rings are made of iron sheets that have been sheared and bent outward, and wrapped with braid. The iron sheets are 0.3-0.6mm thick, 20cm wide, and the length is the outer circumference of casing 1. The braid is approximately 0.1mm thick. The sheared parts of the iron sheets are bent outward at an acute angle of less than 30 degrees, giving the iron sheets the effect of springs.

[0037] The friction expansion ring is tied to the casing 1 with fine steel wire. There are two places in total. The first place (friction expansion ring 1 3) is 20-30 cm downward from the top end of the casing, and the second place (friction expansion ring 2 4) is specifically located 2-2.5 m downward from the top end of the casing 1. The reinforcement depth of the casing 1 can also be adjusted according to needs, but it is necessary to ensure that the spacing between the friction expansion ring 2 4 and the friction expansion ring 1 3 is not less than the length of a single section of the remaining core outer tube 2, and not greater than the length of two single sections of the remaining core outer tube 2.

[0038] The specific lashing method is to cut a 20cm wide sheet of metal, equal to the outer circumference of the casing, into a jagged shape. After bending the sharp corners, it is wrapped with a layer of braided fabric and wrapped around the casing. Three thin steel wires are then used to securely bind the ring. This creates a stable loop of friction expansion rings around the casing. After being tied, the rings take on an outward-flashing, upward-opening trumpet shape. This shape ensures that the casing can only slide downward against the inner wall of the core tube or the borehole wall under a certain thrust, and cannot slide upward in the opposite direction.

[0039] The function of the friction expansion ring 1 (3) is to provide elastic compression and friction. This not only ensures effective friction and compression before the last section of the core outer tube is separated from the casing 1, preventing the casing 1 from falling out of the core outer tube, but also, through its trumpet-shaped outward expansion, creates friction and compression against the borehole wall after the core outer tube is completely lifted and removed, preventing the casing 1 from sliding down and falling out relative to the borehole wall. Finally, when the casing 1 is installed, if grouting is required to reinforce the gap between the casing 1 and the borehole wall, the friction expansion ring 1 (3) can be removed.

[0040] The function of the friction expansion ring 2 4 is, in addition to the function of the friction expansion ring 1 3, that when it is necessary to grout the gap between the casing 1 and the borehole wall to reinforce the casing 1, its outward trumpet-shaped structure can also receive and hold most of the slurry, thereby facilitating the retention and solidification of the slurry and improving the reinforcement effect.

[0041] In the third step, the casing 1 is lowered completely into the core outer tube, and the core outer tube is lifted and removed section by section, leaving only the casing 1 in the borehole. The casing 1 can be lowered manually or by hydraulic pressure from the drilling rig's power shaft. Proceed as follows:

[0042] (1) The top of the casing 1 is connected to the hydraulic pressure of the drilling rig power shaft by a dowel rod 7, which presses the casing 1 downward until the top of the casing 4 is lowered below the threaded connection section of the first and second core tube sections. The principle is to not affect the threaded connection of the threaded head joint of the core tube. The length of the dowel rod 7 is 20-30 cm longer than the length of a single core tube section.

[0043] (2) Then use the threaded head joint to connect the core outer tube, and the drilling rig power shaft pulls the threaded head joint to lift and remove the first section of the core outer tube.

[0044] (3) Use the force transmission rod to transmit the hydraulic pressure of the drilling rig power shaft to press the casing 1 downward to the bottom of the threaded connection section of the second and third core outer pipes.

[0045] (4) Then use the threaded head joint to connect the core outer tube, and the drilling rig power shaft pulls the threaded head joint to lift and remove the second section of the core outer tube.

[0046] (5) Repeat the above steps (1) to (4) to continue disassembling the core outer tube until the last two sections of the core outer tube are left. Instead of using the force transmission rod to press down the casing 1, directly use the threaded head joint to lift and disassemble the second to last section of the core outer tube.

[0047] (6) After disassembling the second-to-last section of the core outer tube, press the casing 1 down to below the top threaded connection section of the first-to-last section of the core outer tube. At this time, the friction expansion ring 2 4 at the bottom of the casing 1 is separated from the first-to-last section of the core outer tube and elastically opens to a larger angle, contacting and rubbing against the borehole wall.

[0048] (7) The threaded head joint is used to connect and lift the penultimate core outer tube. Due to the large friction between the outer bell mouth of the friction expansion ring 2 (4) at the bottom of the casing and the borehole wall, the casing 1 is blocked by the rock and soil layer of the borehole wall. The upward sliding resistance of the casing 1 is large. If the formation collapses or shrinks at this time, this blocking effect is more obvious. However, the friction between the friction expansion ring 1 (3) at the top of the casing 1 and the inner wall of the core outer tube does not have much resistance to the lifting of the penultimate core outer tube. At this time, during the process of connecting the penultimate core outer tube with the threaded head joint and rotating and lifting, the casing 1 and the penultimate core outer tube will inevitably separate. At this point, all the core outer tubes have been removed, and the casing 1 is left in the borehole, just supporting the formation section 5 that is prone to collapse and necking.

[0049] (8) In order to ensure the stability of the casing 1 and prevent it from sliding down, the top of the casing 1 can be tied with a steel wire. If necessary, a hole can be drilled in the top of the casing 1 to pass the steel wire through. The steel wire is tied to the anchor nail hammered into the rock and soil layer around the hole, so as to suspend the casing 1 and stabilize the casing 1 together with the friction force provided by the friction expansion ring 1 3 and the friction expansion ring 2 4.

[0050] When it is necessary to further reinforce the casing 1 by grouting, if the top friction expansion ring 3 hinders grouting, the friction expansion ring 3 can be manually touched at the top of the hole, so the friction expansion ring 3 can be removed or destroyed first, and then quick-setting cement slurry can be poured into the gap between the casing 1 and the borehole wall to further reinforce the casing 1. During grouting, the trumpet shape of the friction expansion ring 2 4 can form a barrier to the slurry, which helps the slurry in the gap above the friction expansion ring 2 4 to be retained and quickly solidified.

[0051] Working Principle: First, use a double-layer core barrel drilling rig to drill to the final hole depth specified by the design, specifications, standards, or technical requirements. First, completely remove the inner core barrel and the core, then remove part of the outer core barrel, leaving a portion of the outer core barrel so that the bottom of this portion of the outer core barrel extends at least 30 cm below the bottom edge of the easily collapsed or necked formation 5, and the top of this portion of the outer core barrel is at least 20 cm above the ground. This is referred to as the remaining outer core barrel 2. Select and determine the specifications and dimensions of the casing 1, and fabricate the friction expansion ring. The outer diameter of the casing 1 must match the inner diameter of the outer core barrel. The outer diameter of the casing 1 is 15-30 mm smaller than the inner diameter of the outer core barrel and the inner diameter of the drill bit. The inner diameters of the outer core barrel and the drill bit are essentially the same, with a typical difference of 1-2 mm. The total length of the casing 1 must be at least one section longer than the total length of the remaining outer core barrel 2. Casing 1 is connected to the inner wall of the core outer tube through frictional compressive force, generated by friction expansion rings. These rings are made of zigzag-sheared, bent iron sheets wrapped in braid. The iron sheets are 0.3-0.6mm thick, 20cm wide, and approximately 0.1mm thick. The sheared sections of the iron sheets are bent and stretched outward at an acute angle of less than 30 degrees. The friction expansion rings are tied to casing 1 with fine steel wire at two locations: the first (friction expansion ring 1 3) is located 20-30cm below the top end of the casing, and the second (friction expansion ring 2 4) is located 2-2.5m below the top end of casing 1. Casing 1 is lowered completely into the core outer tube, then lifted and removed section by section, leaving only casing 1 in the hole. Casing 1 can be lowered manually or with hydraulic pressure from the drill rig's power shaft.

[0052] Proceed as follows: Use dowel rod 7 at the top of casing 1 to transmit hydraulic pressure from the drill rig's power shaft, pressing casing 1 downward until the top of casing 1 descends below the threaded connection between the first and second core tube sections. Then, connect the core tube with a threaded head connector. The drill rig's power shaft pulls the threaded head connector upward to remove the first core tube section. Use dowel rod 7 again to transmit hydraulic pressure from the drill rig's power shaft, pressing casing 1 downward until it reaches below the threaded connection between the second and third core tube sections. Then, connect the core tube with a threaded head connector. The drill rig's power shaft pulls the threaded head connector upward to remove the second core tube section. Repeat these steps to continue removing core tube sections until only the last two core tube sections remain. At this point, use the threaded head connector to directly lift and remove the penultimate core tube section, discontinuing the dowel rod from pressing down on casing 1. After removing the penultimate core tube, the casing 1 is pressed down to below the threaded connection at the top of the penultimate core tube. At this point, the friction ring 2 (4) at the bottom of the casing 1 disengages from the penultimate core tube and elastically expands to a greater angle, engaging and rubbing against the borehole wall. The penultimate core tube is then connected and lifted using the threaded head connector. Due to the significant friction between the outer flared opening of the friction ring 2 (4) at the bottom of the casing 1 and the borehole wall, the casing 1 is caught in the rock and soil of the borehole wall, creating significant resistance to upward sliding. This resistance is even more pronounced if the formation collapses or shrinks. However, the friction between the friction ring 1 (3) at the top of the casing 1 and the inner wall of the core tube does not significantly resist the lifting of the penultimate core tube. Therefore, during the process of connecting the penultimate core tube with the threaded head connector and rotating and lifting, the casing 1 and the penultimate core tube inevitably separate. At this point, all core tubes have been removed, leaving casing 1 in the borehole, precisely supporting the easily collapsed and necked-down formation section 5. To ensure the stability of casing 1 and prevent it from sliding, the top of casing 1 can be secured with wire. If necessary, a hole can be drilled through the top of casing 1 to pass the wire through, which is then tied to an anchor driven into the rock and soil around the hole.

[0053] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anti-collapse casing tool for formation drilling exploration, comprising a casing (1), characterized in that: The casing (1) is inside the remaining core outer tube (2), and the casing (1) can only slide downward relative to the remaining core outer tube (2) and cannot slide upward; the remaining core outer tube (2) is a core outer tube drilling tool for a double-layer core drilling process; the outside of the casing (1) is fixedly connected with a friction expansion ring (3) and a friction expansion ring (4); the friction expansion ring (3) is located at a relatively close distance downward from the top end of the casing (1); the spacing between the friction expansion ring (4) and the friction expansion ring (3) is not less than one single section length of the remaining core outer tube (2) and not greater than two single sections lengths of the remaining core outer tube (2); the outer diameter of the casing (1) is 15-30 mm smaller than the inner diameter of the remaining core outer tube (2); the total length of the casing (1) is at least one single section length longer than the total length of the remaining core outer tube (2).

2. The anti-collapse casing tool for formation drilling exploration according to claim 1, characterized in that: The bottom end of the remaining core outer tube (2) extends downward beyond the bottom boundary of the easily collapsed or necked stratum (5) and enters the lower relatively intact stratum (6) by at least 30 cm, and the top end of the remaining core outer tube (2) is exposed above the ground by at least 20 cm.

3. The anti-collapse casing tool for formation drilling exploration according to claim 2, characterized in that: The friction expansion ring 1 (3) and the friction expansion ring 2 (4) have the same size specifications and are made in the same way; the friction expansion ring 1 (3) and the friction expansion ring 2 (4) are made of iron sheets that have been sheared and bent outward and wrapped with braided fabric, and their length is the outer circumference of the sleeve. The sheared part of the iron sheets is bent outward, and the outward angle is an acute angle of less than 30 degrees; the friction expansion ring 1 (3) and the friction expansion ring 2 (4) are in the shape of a trumpet with the opening facing upward.

4. The anti-collapse casing tool for formation drilling exploration according to claim 1, characterized in that: The downward sliding of the casing (1) relative to the remaining core outer tube (2) is achieved by the hydraulic pressure of the drilling rig power shaft transmitted by the dowel rod (7), the length of the dowel rod (7) is 20-30 cm longer than the length of a single section of the core outer tube, and the diameter of the dowel rod (7) is consistent with that of the casing (1).

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