Drilling wall protection method and smart casing

Abstract

This invention relates to the technical field of drilling for energy resources such as oil and gas, geothermal, and coal, as well as scientific drilling engineering. In particular, it relates to a drilling wall protection method and an intelligent casing, comprising the following steps: providing an intelligent casing; based on the lower end of the casing being closed, inserting the flexible, flat casing into a predetermined position within the borehole; based on the upper end of the casing being connected to a fluid source, injecting a fluid medium into the casing to cause radial expansion and adhesion to the borehole wall; placing a solidification source inside the casing and moving the solidification source along the axial direction of the casing, causing the casing to gradually solidify from one end to the other, forming a hard wall protection layer. The beneficial effects are that operators can flexibly adjust the starting position and length of the casing within the borehole according to the actual geological conditions, thereby significantly improving the targeting and flexibility of the operation, simplifying the wall protection procedure, greatly reducing costs, and even enabling constant-diameter drilling.

Description

Technical Field

[0001] This invention relates to the technical field of drilling for energy resources such as oil and gas, geothermal energy, and coal, as well as scientific drilling engineering, and particularly to a drilling wall protection method and intelligent casing. Background Technology

[0002] Drilling casing is a type of tubing used to support the borehole wall, ensuring smooth drilling and the normal operation of the entire oil well after completion. In drilling, conventional casings are typically made of steel tubing and are non-reusable, belonging to the category of disposable consumable materials. Casing consumption accounts for more than 70% of all oil well tubing. The casing cementing process generally involves drilling, well cleaning, logging, well cleaning again, casing installation, cementing, waiting for curing, plugging, and then proceeding to the next drilling cycle. Conventional casings are relatively long, making transportation inconvenient and construction complex. After casing installation, a smaller diameter drill bit must be used to continue drilling through the casing, and logging operations that are significantly affected by the magnetic material of the casing cannot be performed in the casing section. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a drilling wall protection method and an intelligent casing, which solves the technical problems of the existing steel casing cementing process, such as complicated construction process, inconvenient transportation, gradual reduction of well diameter, and magnetic interference of the casing with logging.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0007] In a first aspect, the present invention provides a method for borehole wall protection, characterized by comprising the following steps:

[0008] S1: Insert the uncured sheath into a predetermined position inside the hole. The sheath is a flexible, expandable part with an injection cavity inside.

[0009] S2: The uncured sheath is connected to the fluid source, and fluid medium is injected into its injection chamber to make the uncured sheath expand into a cylindrical shape and fit against the hole wall;

[0010] S3: Place a curing source inside the uncured sheath. The curing source will cure the cylindrical sheath into a hard protective layer that adheres to the hole wall.

[0011] In one technical solution of the present invention, in S1, the uncured sheath is sent into a predetermined position in the borehole, specifically including: detachably connecting the open end of the sheath and the open end of the drill rod through a tooling, and sending the sheath into a predetermined position in the borehole through the drill rod, wherein the injection cavity of the sheath is connected to the inner cavity of the drill rod.

[0012] In S2, the uncured sheath is connected to the fluid source, and fluid medium is injected into its injection cavity. Specifically, the drill pipe is connected to the fluid source, and fluid medium is injected into the injection cavity of the uncured sheath through the inner cavity of the drill pipe.

[0013] In S3, a curing source is placed inside the uncured sheath. Specifically, this includes placing the curing source into the injection cavity of the sheath through the inner cavity of the self-drilling rod of the hoisting device.

[0014] In one technical solution of the present invention, in S3, the curing source is moved along the axial direction of the sheath, so that the sheath is gradually cured from one end to the other.

[0015] In one embodiment of the present invention, after S3, it further includes:

[0016] S4: Once the sheath has cured, disconnect the sheath from the drill pipe, remove the curing source, tooling, and drill pipe from the borehole, and drill down to remove the closed blind end at the lower end of the sheath for equal-diameter drilling.

[0017] In one embodiment of the present invention, the curing source has a cutting device to disconnect the sheath from the drill pipe after the sheath has cured.

[0018] In one technical solution of the present invention, before S1, it further includes:

[0019] S0: Enlarge the hole to be sealed using a reaming drill bit.

[0020] In one technical solution of the present invention, the borehole is a wellbore.

[0021] Secondly, the present invention provides a curable smart sheath, which includes, from the outside to the inside, a protective layer, an outer fabric layer, a curable layer, and an inner fabric layer.

[0022] The sheath can go from a self-retracting state to a support state after a curing process.

[0023] In its stored state, the sheath is flat and folded, and can expand to a circular cross-section under the action of internal fluid pressure, and solidify and set under the action of a curing source to enter the support state.

[0024] In one embodiment of the present invention, the curable layer comprises a curable fiber fabric and a photosensitive and / or thermosensitive curable material impregnated therein.

[0025] In one technical solution of the present invention, after the sheath is cured and shaped, the volume elongation is not less than 50%, the external pressure resistance is not less than 20MPa, and the internal pressure resistance is not less than 80MPa.

[0026] (III) Beneficial Effects

[0027] The beneficial effects of this invention are as follows: In the borehole wall protection method of this invention, the sheath is pre-sealed at the lower end and can be stored and transported in a flat, rolled state. When the flat sheath is inserted into a predetermined position within the borehole, because the sheath is initially soft and foldable, it can significantly reduce downhole resistance, adapt to narrow wellbore passages, and facilitate long-distance transport.

[0028] Subsequently, with the upper end of the casing connected to a fluid source, a fluid medium is injected into the casing. Due to the pressure of the fluid flow, the casing expands radially and fits tightly against the borehole wall surface. Because the casing can conform to the undulating shape of the borehole wall during expansion, a seal between the casing and the borehole wall can be achieved without additional cementing operations, thus simplifying the construction process.

[0029] Next, a curing source is placed inside the sheath and moved along the axial direction of the sheath, causing the sheath to gradually cure from one end to the other, forming a hard protective layer with high elastic modulus, good flexural and tensile strength, and superior corrosion resistance. Because the curing process is gradual, the curing area can be precisely controlled, avoiding the problem of shrinkage stress concentration caused by one-time curing. Furthermore, since the cured sheath has low hardness and is easy to grind, it facilitates subsequent localized trimming or drilling as needed.

[0030] In addition, the casing can be made of non-magnetic materials. Due to its non-magnetic properties, the casing will not interfere with electromagnetic detection operations such as logging or measurement while drilling after it is formed. Since the casing is soft and flat before curing, it expands to fit the borehole wall and forms a continuous casing with the same diameter as the well, thus enabling constant diameter drilling and avoiding the well diameter reduction problem caused by traditional casings.

[0031] Based on the above method, this wall protection scheme is not only suitable for temporary isolation of open-hole sections or temporary support of locally complex sections, but also for repairing large sections of corroded casing, and even directly used as the tailpipe of open-hole wells. Due to the adoption of a movable curing source for gradual curing technology, operators can flexibly adjust the starting position and length of the casing support within the borehole according to the actual geological conditions, thereby significantly improving the targeting and flexibility of the operation, reducing overall construction costs, simplifying the wall protection procedure, and even enabling constant-diameter drilling.

[0032] Furthermore, this method can directly utilize existing drilling equipment to achieve borehole wall protection operations without introducing excessive additional equipment, thereby improving work efficiency and reducing equipment costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the wellbore and the structure of the location to be supported before enlargement, as per the present invention.

[0034] Figure 2 This is a schematic diagram of the wellbore and the structure of the location to be supported after enlargement according to the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the present invention after the drill pipe and sheath have been inserted into the position to be supported and the sheath has not expanded.

[0036] Figure 4 This is a schematic diagram of the structure of the present invention after the drill pipe and sheath have been inserted into the position to be supported and the sheath has expanded.

[0037] Figure 5 This is a schematic diagram of the structure of the curing source of the present invention during the curing operation;

[0038] Figure 6 This is a schematic diagram of the structure when the curing source of the present invention has been cured and the connection between the sheath and the drill pipe is disconnected by a cutting device;

[0039] Figure 7 This is a schematic diagram of the structure after the sheath support of the present invention is completed and the closed blind end at the lower end of the sheath is removed by drilling.

[0040] Figure 8 This is a schematic diagram of the structure of the sheath of the present invention in the support state;

[0041] Figure 9 This is a schematic diagram of the structure of the sheath of the present invention when it is in the storage state.

[0042] Explanation of reference numerals in the attached figures

[0043] 1: Sheath; 11: Protective layer; 12: Outer fabric layer; 13: Curable layer; 14: Inner fabric layer;

[0044] 2: Pore;

[0045] 3: Curing source;

[0046] 4: Tooling;

[0047] 5: Drill pipe;

[0048] 6: Cutting device. Detailed Implementation

[0049] To better explain and facilitate understanding of this invention, the following description is provided in conjunction with the appendix. Figures 1-9 The present invention will be described in detail through specific embodiments. In this document, directional terms such as "upper" and "lower" are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference.

[0050] Example 1:

[0051] Reference Figures 1-9 The present invention provides a borehole wall protection method, comprising the following steps:

[0052] S1: The uncured sheath 1 is inserted into the hole 2 at a predetermined position. The sheath 1 is a flexible part that can be stretched and has an injection cavity inside. The uncured sheath 1 can be folded and flattened before entering the hole 2.

[0053] S2: The uncured sheath 1 is connected to the fluid source, and a fluid medium is injected into its injection chamber to make the uncured sheath 1 expand into a cylindrical shape and fit against the hole wall; the fluid medium can be water or air.

[0054] S3: Place curing source 3 inside the uncured sheath 1. Curing source 3 cures the cylindrical sheath 1 into a hard protective layer that adheres to the hole wall.

[0055] Before curing, the sheath 1 is in a soft, flat state, allowing for storage and transportation in rolls. After curing, it possesses high elastic modulus, flexural and tensile strength, and good corrosion resistance, but its low hardness makes it easy to grind. Due to its initial soft nature, it can adhere tightly to the borehole wall, eliminating the need for cementing operations and simplifying the process. Using non-magnetic materials, it does not affect logging and measurement while drilling operations after wall protection. It enables drilling of the same diameter, and the construction process is simple and cost-effective. It can be used for open-hole section isolation, temporary wall protection in complex local sections, repair of large sections of corroded sheath 1, and even as open-hole tailpipe.

[0056] This technical solution allows for adjustment of the specific support position of the sheath 1 within the bore 2 as needed, improving operational flexibility.

[0057] Specifically, this technical solution first provides an intelligent sheath 1, whose intelligence is reflected in its ability to expand and adaptively fit the hole wall. The sheath 1 is pre-sealed at the lower end and can be stored and transported in a flat state in rolls.

[0058] In step S1, the sheath 1, which is in a flat state, is sent into a predetermined position in the borehole. Since the sheath 1 is initially soft and foldable, it can significantly reduce the resistance to going down into the well, adapt to narrow wellbore passages, and facilitate long-distance transport.

[0059] In step S2, with the upper end of the casing 1 connected to a fluid source, a fluid medium is injected into the casing 1. Due to the pressure of the fluid flow, the casing 1 expands radially and fits tightly against the borehole wall surface. Since the casing 1 can conform to the undulating shape of the borehole wall during expansion, a seal between the casing 1 and the borehole wall can be achieved without additional cementing operations, thus simplifying the construction process.

[0060] In step S3, a curing source 3 is placed inside the sheath 1 and moved along the axial direction of the sheath 1, thereby gradually curing the sheath 1 from one end to the other, forming a hard protective layer with high elastic modulus, good bending and tensile strength, and superior corrosion resistance. Because the curing process is carried out in a step-by-step manner, the curing area can be precisely controlled, avoiding the problem of shrinkage stress concentration caused by one-time curing. At the same time, because the cured sheath 1 has low hardness and is easy to grind, it is convenient for subsequent local trimming or drilling as needed.

[0061] In addition, the material of the sheath 1 can be a non-magnetic material. Due to its non-magnetic properties, the sheath wall will not interfere with electromagnetic detection operations such as logging or measurement while drilling after it is formed. Since the sheath 1 is in a soft and flat state before curing, it expands and fits the borehole wall. After curing, it forms a continuous sheath wall with the same diameter as the well. Therefore, it can achieve constant diameter drilling and avoid the well diameter reduction problem caused by traditional sheath 1.

[0062] Based on the above method, this wall protection scheme is not only suitable for temporary isolation of open hole sections or temporary support of locally complex sections, but also for repairing large sections of corroded casing 1, and even directly used as the tailpipe of open hole wells. Due to the adoption of a movable curing source 3 for gradual curing technology, operators can flexibly adjust the starting position and length of the casing 1 within the borehole body 2 according to the actual geological conditions inside the borehole, thereby significantly improving the targeting and flexibility of the operation and reducing the overall construction cost.

[0063] The sheath 1 comprises, from the outside in, a protective layer 11, an outer fabric layer 12, a curable layer 13, and an inner fabric layer 14. The protective layer can be a rubber layer. The sheath 1 can transition from a retracted state to a support state through a curing process. In the retracted state, the sheath 1 is in a flat, folded shape and can expand to a circular cross-section under internal fluid pressure, and then be cured and shaped by the curing source 3 to enter the support state.

[0064] When stored, the protective sleeve 1 can be referenced. Figure 9 The folding method shown can be folded from both ends towards the middle, folded in half, or simply flattened for storage. The first two methods help reduce the lateral space occupied by the sheath 1 after folding, while the latter method is more conducive to the rapid and full expansion of the sheath 1 under medium pressure, but it will occupy more lateral space after folding. The choice can be made flexibly by the relevant personnel.

[0065] The curable layer 13 comprises a curable fibrous fabric and a photosensitive and / or heat-sensitive curing material impregnated therein. The curing source 3 is a light source or heat source of a specific wavelength.

[0066] In this embodiment, the intelligent sheath 1 adopts a multi-layer composite structure, consisting of a protective layer 11, an outer fabric layer 12, a curable layer 13, and an inner fabric layer 14, arranged from the outside in. The protective layer 11 effectively isolates the curable layer 13 from the erosion caused by downhole mud or formation fluids. The outer and inner fabric layers 12 and 14 provide load-bearing and constraint, ensuring the curable layer 13 is evenly distributed during expansion. The sheath 1 can be transformed from a stored state to a support state through a curing process. In the stored state, the sheath 1 is flat and folded, facilitating roll storage and downhole transport. When fluid is injected, the sheath 1 expands radially to a circular cross-section and adheres to the borehole wall due to fluid pressure. Subsequently, under the action of the curing source 3, the curable layer 13 gradually solidifies and sets, allowing the sheath 1 to enter a high-strength support state. Because a step-by-step molding method of expansion followed by curing is adopted, the problem of the soft sheath 1's downhole passability is solved, while ensuring the geometric integrity and mechanical stability of the final protective layer.

[0067] The aforementioned curable layer 13 specifically comprises a curable fiber fabric and a photosensitive and / or heat-sensitive curing material impregnated therein. Correspondingly, the curing source 3 is a light source or heat source of a specific wavelength. Due to the use of a photosensitive or heat-sensitive curing system, when the curing source 3 moves along the axial direction of the casing 1, only localized areas need to be irradiated or heated to initiate the curing reaction. This avoids excessive heat or light energy concentration caused by simultaneous curing throughout the entire well section, and allows for precise control of gradual curing from one end of the casing 1 to the other. Furthermore, since the type of curing source 3 can be flexibly selected according to well conditions—for example, a light source of a specific wavelength can be used in a water-bearing environment, while a heat source can be used in dry or high-temperature formations—it can adapt to the construction requirements of different drilling environments.

[0068] Specifically, curable fiber fabrics can be blends of any one or more of glass fiber, carbon fiber, aramid fiber, and basalt fiber.

[0069] The curing material can be a photocurable system, such as unsaturated polyester resin, vinyl ester resin, epoxy resin, or polyurethane acrylate, combined with a suitable photoinitiator. It can also be a thermocurable system, such as epoxy resin or polyurethane combined with a latent curing agent, or a photo-thermal dual curing system that combines the advantages of both.

[0070] After curing and shaping, the casing 1 has a volumetric elongation of not less than 50%, an external pressure resistance of not less than 20 MPa, and an internal pressure resistance of not less than 80 MPa. Due to its large volumetric elongation, the casing 1 can fully fill the gap between the borehole wall and the casing 1 after expansion, ensuring a tight fit even in cases of localized wellbore enlargement. Its external pressure resistance of over 20 MPa can resist formation collapse pressure or external fluid column pressure, preventing the casing layer from being crushed. The internal pressure resistance of not less than 80 MPa ensures that the casing 1 will not crack or leak during subsequent drilling fluid circulation, fracturing, or logging operations. Based on these properties, the hard casing layer formed after curing not only has sufficient load-bearing capacity, but also, due to its smooth inner wall and consistent diameter, facilitates the insertion and operation of subsequent tools, further improving the reliability and construction efficiency of the borehole casing.

[0071] Example 2:

[0072] Reference Figures 1-9 In addition to possessing all the technical solutions of the above embodiments, the embodiments of the present invention further possess the following technical solutions:

[0073] In step S1, the uncured sheath 1 is inserted into a predetermined position within the borehole 2. Specifically, this involves: detachably connecting the open end of the sheath 1 to the open end of the drill rod 5 using a tooling 4; and inserting the sheath 1 into the predetermined position within the borehole 2 using the drill rod 5. The filling chamber of the sheath 1 is connected to the inner cavity of the drill rod 5. The top end of the drill rod 5 can be sealed using a sealing ring or plug to prevent excessive leakage of the medium fluid when it is injected into the filling chamber to expand the sheath 1. Minor leakage of the medium fluid can be compensated for by increasing the medium fluid pressure, thus ensuring sufficient pressure within the filling chamber for expansion and adhesion to the borehole wall.

[0074] In S2, the uncured sheath 1 is connected to the fluid source, and a fluid medium is injected into its injection cavity. Specifically, the drill pipe 1 is connected to the fluid source, and a fluid medium is injected into the injection cavity of the uncured sheath 1 through the inner cavity of the drill pipe 1.

[0075] In S3, a curing source 3 is placed inside the uncured sheath 1. Specifically, the curing source 3 is placed into the injection cavity of the sheath 1 through the inner cavity of the self-drilling rod 5 of the hoisting device.

[0076] The tooling 4 connects the open end of the sheath 1 to the open end of the drill rod 5, and the drill rod 5 is used to feed the sheath 1 into the predetermined position in the borehole 2. The tooling 4 can be a clamp, which clamps the upper opening of the sheath to the lower end of the drill rod 5, which will not be described in detail here.

[0077] The lower end of the casing 1 can be sealed by locking with a non-metallic material such as plastic. Alternatively, it can be factory-sealed, for example, by pre-sealing one end of the long casing 1. With the former approach, the casing 1 can be cut to the required length on-site, with one end connected to the drill pipe 5 via tool 4 and the other end locked with a locking device, making it more suitable for scenarios with shorter support lengths. The latter approach, where the casing 1 has a pre-sealed end at the factory, eliminates the need for additional locking devices if the wellbore to be supported is long, making it suitable for scenarios with longer support lengths.

[0078] In this embodiment, the process of inserting the flexible, flat sheath 1 into a predetermined position within the borehole 2 can be carried out in the following manner: a tool 4 is used to connect the upper end of the sheath 1 to the lower end of the drill rod 5, and then the sheath 1 is conveyed to a specified depth within the borehole by the advancement of the drill rod 5. Because the tool 4 is used for connection, the existing drilling capability of the drilling rig can be utilized for inserting the sheath 1, eliminating the need for additional dedicated conveying equipment and simplifying on-site equipment.

[0079] The tooling 4 is preferably in the form of a clamp. Due to the clamp structure, a uniform clamping force can be applied to the end of the flat and curled sheath 1, which not only ensures reliable connection and prevents slippage during feeding, but also avoids damage to the protective layer 11 or the internal fabric structure of the sheath 1 due to excessive local stress.

[0080] Driven by the drill pipe 5, the main body of the casing 1 relies on its own weight and drilling pressure to pass through the narrow gap well section. Its flexible and flat shape can continue to play the advantage of reducing frictional resistance and smoothly passing through complex wellbore trajectories.

[0081] In this embodiment, the curing source 3 is connected to the end of the hoisting device and lowered through the water hole inside the drill rod 5, allowing it to enter the grouting chamber inside the sheath 1. At this time, the upper end of the drill rod 5 is connected to the ground lifting or winch equipment, while its lower end remains connected to the upper end of the sheath 1 through the tooling 4.

[0082] By employing a hoisting device to deliver the curing source 3 directly into the cavity of the drill rod 5, the already positioned drill rod 5 can be used as a guide and protection channel, eliminating the need for a separate conversion process of removing the drill rod 5 and then lowering the curing tool string, thus significantly shortening the operation time. Because the inner wall of the drill rod 5 is straight and the gap is controllable, the curing source 3 will not experience uncontrolled scraping against the inner wall of the sheath 1 during transport, protecting the optical or thermal components of the curing source 3 from impact damage and preventing accidental wear on the uncured sheath 1. Simultaneously, the hoisting device can be equipped with a depth measuring device to transmit the lowering depth in real time, ensuring that the curing source 3 can be accurately lowered to the predetermined starting position of the sheath 1. Since the initial position of the curing source 3 is precisely calibrated, a reliable foundation is laid for subsequent uniform movement at a predetermined speed and gradual axial curing, ensuring that the curing reaction of each section of the sheath 1 is fully completed within the set time.

[0083] Since the curing source 3 can gradually cure the sheath 1, it can ensure the uniformity of curing of the sheath, improve its adhesion to the hole wall, and thus improve the support effect.

[0084] Example 3:

[0085] Reference Figures 1-9 In addition to possessing all the technical solutions of the above embodiments, the embodiments of the present invention further possess the following technical solutions:

[0086] After S3, S4 is also included: based on the completion of the curing of the sheath 1, disconnect the connection between the sheath 1 and the drill rod 5, and remove the curing source 3, tooling 4 and drill rod 5 from the hole body 2, and drill down to sweep away the closed blind end at the lower end of the sheath 1 in order to carry out equal diameter drilling.

[0087] In this embodiment, since the cured sheath 1 has formed an independently load-bearing hard protective wall layer, it no longer needs internal support or external suspension. Therefore, it can be sent into the tool string for recovery, clearing out a complete and unobstructed wellbore passage.

[0088] Subsequently, the drill string was lowered back in to mechanically remove the pre-sealed blind end at the lower end of the casing 1. Because the cured material of casing 1 retains its low hardness and ease of grinding after hardening, this sealed end can be quickly milled through by the drill bit. Using this technique, the sealed blind end ensures no leakage occurs at the lower end of casing 1 during fluid injection in the early stages of operation, allowing the expansion pressure to be fully established and evenly transmitted to the pipe wall. After its purpose is fulfilled, it can be efficiently removed, preventing it from becoming an obstacle to subsequent drilling.

[0089] With the lower end seal removed, the formation at the bottom of the borehole is fully exposed, and the inner diameter of the solidified casing layer at this point becomes the designed wellbore diameter for this drilling operation. Because the casing layer achieves a uniform diameter fit with the upper borehole wall during expansion and solidification, the drill bit does not need to be reduced in diameter and can continue drilling forward according to the original wellbore size, thus achieving continuous operation of constant-diameter drilling. This process eliminates the need for replacing the drill bit with a smaller size, re-reaming, or adjusting the inner diameter after conventional tailpipe cementing, making the well construction process more streamlined. Furthermore, maintaining a uniform wellbore diameter throughout the well avoids the limitation of gradually shrinking wellbore structures.

[0090] Example 4:

[0091] Reference Figures 1-9 In addition to possessing all the technical solutions of the above embodiments, the embodiments of the present invention further possess the following technical solutions:

[0092] Before S1, it also includes:

[0093] S0: The hole to be sealed is enlarged using a reaming drill bit.

[0094] In this embodiment, before the flat sheath 1 is sent to the predetermined position, the borehole 2 to be sealed can be pre-enlarged using a reaming drill bit. Due to the targeted reaming pretreatment, the original well diameter of the section to be supported is enlarged to a preset diameter, eliminating local narrowing caused by borehole wall shrinkage, formation creep, or rock cuttings accumulation, making the subsequent lowering of the flat sheath 1 smoother and more unobstructed. Simultaneously, the reaming process can scrape away loose mud cake and alteration layers from the borehole wall surface, exposing a solid rock surface. This allows for mechanical interlocking between the solidified sheath layer and the formation after the sheath 1 expands and adheres, significantly improving the sealing effect and structural stability. Furthermore, because the reaming provides a uniform well diameter space, the sheath 1 can fully expand to a circular cross-section under fluid pressure, avoiding pipe wall wrinkles or local stress concentration caused by irregular well diameters. This helps ensure consistent sheath layer thickness after solidification and achieves equal-diameter connection with adjacent well sections, creating conditions for equal-diameter drilling. Furthermore, after the borehole is enlarged, the sleeve 1 can be secured in the enlarged section, which is more conducive to the stable fixation of the sleeve 1 and also helps to improve the overall flatness of the wellbore, avoiding local undulations caused by the installation of the sleeve 1.

[0095] The axial position of the sleeve 1 relative to the hole 2 can be fixed by the friction force after the sleeve 1 is tensioned to the hole wall. Alternatively, the axial position of the sleeve 1 relative to the hole 2 can be fixed by the mutual interlocking between the enlarged hole portion and the expanded sleeve 1 in this embodiment, which is also used to tighten the friction force after the sleeve 1 is tensioned to the hole wall.

[0096] Example 5:

[0097] Reference Figures 1-9In addition to possessing all the technical solutions of the above embodiments, the embodiments of the present invention further possess the following technical solutions:

[0098] The curing source 3 has a cutting device 6 to disconnect the sheath 1 from the drill rod 5 after the sheath 1 has cured. The cutting device 6 can be a water jet assembly, with the water jet tip fixedly connected to the curing source 3 and able to rotate with the torsion of the curing source 3. The output end of the water jet is close to the upper part of the sheath 1 to ensure its cutting effect.

[0099] The output end of the water jet can be directly fixed to the upper part of the curing source 3 by bolts. The water jet's water pipe also extends inside the drill rod 5. The water jet is installed on the ground where the water pump is located.

[0100] In this embodiment, the technical solution of adding a cutting device 6 to the curing source 3 is adopted, which enables the curing and separation processes to be completed on the same tool string, eliminating the need for a separate cutting tool operation, thereby further reducing the construction cycle.

[0101] Because water jet cutting is used, a high-pressure abrasive jet can be used to precisely cut the upper connecting section of the cured sheath 1 in a circumferential direction. Since the cured sheath layer is easy to grind, the water jet can quickly and smoothly cut it off without producing burrs or chipping. As the cutting process is a cold cut, no heat-affected zone is generated, so it will not damage the metal body of the drill pipe 5 or tooling 4 above, nor will it damage the already shaped sheath structure below the cut section. At the same time, since the cutter head is twisted as a whole with the curing source 3, a 360° circumferential cut can be achieved without adding an additional downhole drive mechanism, ensuring that the sheath 1 is completely separated around the circumference. This allows the tooling 4 and drill pipe 5 to cleanly remove the remaining connecting section from the wellbore when they are pulled out, providing a complete borehole for subsequent plugging and equal-diameter drilling.

[0102] The water generated after water jet cutting can be directly in the injection chamber or gradually accumulated in the drill pipe 5, and discharged directly into the wellbore after the blind end of the casing 1 is removed.

[0103] It can be understood that, except for conflicting parts, the above embodiments 1-5 can be freely combined to form other embodiments of the present invention.

[0104] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0105] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0106] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0107] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, articles, or apparatus / devices.

[0108] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method of drilling a retaining wall, characterized by, Includes the following steps: S1: Insert the uncured sheath (1) into the predetermined position inside the hole (2). The sheath (1) is a flexible part that can be stretched and has an injection cavity inside. S2: The uncured sheath (1) is connected to the fluid source, and fluid medium is injected into its injection cavity so that the uncured sheath (1) is expanded into a cylindrical shape and fits against the hole wall; S3: Place a curing source (3) inside the uncured sheath (1), and the curing source (3) will cure the cylindrical sheath (1) into a hard protective layer that adheres to the hole wall.

2. The drilling wall protection method as described in claim 1, characterized in that, In S1, the uncured sheath (1) is sent into a predetermined position in the hole (2), specifically including: the open end of the sheath (1) and the open end of the drill rod (5) are detachably connected by the tool (4), and the sheath (1) is sent into a predetermined position in the hole (2) by the drill rod (5), wherein the injection cavity of the sheath (1) is connected to the inner cavity of the drill rod (5); In S2, the uncured sheath (1) is connected to the fluid source and a fluid medium is injected into its injection cavity. Specifically, the drill pipe (1) is connected to the fluid source and a fluid medium is injected into the injection cavity of the uncured sheath (1) through the inner cavity of the drill pipe (1). In S3, a curing source (3) is placed inside the uncured sheath (1), specifically including: placing the curing source (3) into the injection cavity of the sheath (1) through the inner cavity of the self-drilling rod (5) of the hoisting device.

3. The drilling wall protection method as described in claim 1, characterized in that, In S3, the curing source (3) is moved along the axial direction of the sheath (1) so that the sheath (1) is gradually cured from one end to the other.

4. The trench wall protection method according to claim 2, wherein Following S3, it also includes: S4: After the sheath (1) has been cured, disconnect the sheath (1) from the drill rod (5), and remove the curing source (3), tooling (4) and drill rod (5) from the hole (2), and drill down to remove the closed blind end at the lower end of the sheath (1) in order to carry out equal-diameter drilling.

5. The method of bored retaining wall according to claim 4, wherein, The curing source (3) has a cutting device (6) to disconnect the sheath (1) from the drill pipe (5) after the sheath (1) has been cured.

6. The trench wall protection method according to claim 1, wherein Before S1, it also includes: S0: The hole to be sealed (2) is enlarged by using a reaming drill bit.

7. The trench wall protection method according to any one of claims 1 to 6, wherein The borehole (2) is the wellbore.

8. A curable smart sheath, characterized in that, From the outside to the inside, it includes a protective layer (11), an outer fabric layer (12), a curable layer (13), and an inner fabric layer (14). The sheath (1) can enter the support state from the storage state through the curing operation; In its stored state, the sheath (1) is in a flat, folded shape and can expand to a circular cross-section under the action of internal fluid pressure, and is solidified and shaped under the action of the solidification source (3) to enter the support state.

9. The curable smart sheath (1) as described in claim 8, characterized in that, The curable layer (13) comprises a curable fiber fabric and a photosensitive and / or heat-sensitive curable material impregnated therein.

10. The curable smart sheath (1) as described in claim 8, characterized in that, After the sheath (1) is cured and shaped, its volume elongation is not less than 50%, its external pressure resistance is not less than 20MPa, and its internal pressure resistance is not less than 80MPa.

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