Large size well cement-based pipe column for deep underground space utilization and related methods

Abstract

This invention discloses a large-size cement-based tubing string and related methods for utilizing deep underground spaces. The cement-based tubing string includes: a reinforcing cage, ultra-high performance concrete encasing the reinforcing cage, and joints connecting the two ends of the reinforcing cage; the reinforcing cage includes longitudinal reinforcement and spiral reinforcement; multiple vortex grooves are provided on the inner wall of the cement-based tubing string; and a spiral texture is provided on the outer wall of the cement-based tubing string. This cement-based tubing string can be applied to the utilization of deep underground spaces such as salt caverns and depleted oil and gas reservoirs, exhibiting good sealing properties, corrosion resistance, fluid erosion resistance, and high tensile and torsional mechanical properties. Using the cement-based tubing string allows for direct injection and production operations within the wellbore, eliminating the need for separate injection and production tubing in traditional underground energy storage systems, providing a more economical and reliable process system for the construction and operation of exploitable deep underground wells.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage library drilling and completion technology, and particularly relates to a large-size well cement-based pipe column for deep underground space utilization and a related method. BACKGROUND

[0002] Deep underground storage spaces such as underground salt caverns and depleted oil and gas reservoirs have good pressure-bearing capacity and sealing performance, and have broad development prospects in the fields of energy storage, hydrogen storage, helium storage, and carbon storage. In current well construction projects of these energy storage libraries, a metal casing is used for cementing operations, and an injection and production pipe for injecting and producing gas is sleeved in the metal casing.

[0003] Since the injection and production pipe is mainly made of metal material, corrosion problems are serious during use. Although corrosion prevention treatment can be performed by using a Cr / Ni alloy combined with a fusion welding process, or by using cathodic protection, corrosion-resistant coating / inhibitor, etc., the corrosion rate can only be reduced to a certain extent, the corrosion problem of the injection and production pipe cannot be fundamentally solved, and the construction cost in the early stage and the maintenance cost in the later stage are inevitably increased. After the well construction is completed, the periodic injection and production of gas will form alternating loads, and the pipe wall of the injection and production pipe will be damaged under the action of alternating gas flow during long-term use, affecting the service life and injection and production quality of the injection and production pipe. The above problems may cause hidden dangers to the stable operation of the system and become an important bottleneck restricting the long-term stable operation of underground energy facilities. SUMMARY

[0004] In view of the above problems, the present application is proposed to provide a large-size well cement-based pipe column for deep underground space utilization and a related method to overcome the above problems or at least partially solve the above problems.

[0005] In a first aspect, an embodiment of the present application provides a large-size well cement-based pipe column for deep underground space utilization, comprising:

[0006] a steel reinforcement cage, ultra-high performance concrete wrapped around the steel reinforcement cage, and a joint connected to both ends of the steel reinforcement cage;

[0007] The steel reinforcement cage comprises longitudinal reinforcement and spiral reinforcement.

[0008] A plurality of vortex grooves are arranged on the inner wall of the cement-based pipe column.

[0009] A spiral texture is arranged on the outer wall of the cement-based pipe column.

[0010] In an embodiment, the large-size well cement-based pipe column further comprises:

[0011] a stress enhancement structure;

[0012] The stress-enhancing structure is installed on the joint to share the locally increased stress generated at the connection between the longitudinal reinforcement and the joint during the construction of the cement-based tubular well.

[0013] In one embodiment, the stress-enhancing structure is a scissor-shaped rib structure;

[0014] The scissor-shaped rib structure is located within the area where the longitudinal rib connects to the joint.

[0015] In one embodiment, the stress-enhancing structure is a covered cylindrical structure;

[0016] The covered cylindrical structure is connected to the end of the longitudinal rib.

[0017] In one embodiment, the longitudinal ribs are at an angle of 0° to 15° to the longitudinal direction.

[0018] Secondly, embodiments of the present invention provide a method for preparing the above-mentioned cement-based tubular column, comprising:

[0019] Prepare steel cages using iron-based shape memory alloys as reinforcing materials;

[0020] Joints are provided at both ends of the reinforcing cage;

[0021] Using prefabricated molds, ultra-high performance concrete is poured into the molds and cured to form cement-based pipe columns with multiple vortex grooves on the inner wall and spiral textures on the outer wall.

[0022] In one embodiment, after the step of setting joints at both ends of the reinforcing cage and before the step of pouring ultra-high performance concrete, the method further includes: fabricating a stress-reinforcing structure on the joints.

[0023] In one embodiment, the stress-enhancing structure is a scissor-shaped rib structure;

[0024] The rib structure is manufactured in the following manner:

[0025] Within the connection range between the longitudinal rib and the joint, scissor-shaped ribs are welded between each pair of longitudinal ribs, and the ribs are welded to the joint to form the rib structure.

[0026] In one embodiment, the stress-enhancing structure is a covered cylindrical structure;

[0027] The covered cylindrical structure is manufactured by the following method:

[0028] A columnar covering cylinder with a cross-sectional area larger than that of the longitudinal rib is welded to the end of the longitudinal rib and the outer wall of the joint to form the covering cylindrical structure.

[0029] Thirdly, embodiments of the present invention provide a well construction method using the above-mentioned cement-based tubing string, comprising:

[0030] Determine the drilling sequence;

[0031] Perform drilling operations in each phase, and use metal casing for corresponding cementing operations;

[0032] After the final drilling operation, the cement-based tubing is connected in sequence and lowered into the well to complete the cementing operation.

[0033] In one embodiment, the cement-based tubular column is connected by either a threaded connection or a welded connection.

[0034] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0035] The large-size cement-based tubing provided in this invention, designed for deep underground space utilization, can be applied in fields such as salt caverns and depleted oil and gas reservoirs. It exhibits excellent sealing and integrity during high-frequency injection and production of hydrogen, oxygen, or other acidic media. Due to its cement-based material, the tubing possesses excellent corrosion resistance. Because of its similar mechanical properties to cement sheaths, it significantly reduces the damage to the bonding surface caused by alternating loads generated during fluid injection and production. Multiple vortex grooves on the inner wall of the tubing greatly reduce the erosion effect of high-speed fluids on the inner wall. Spiral textures on the outer wall significantly improve the bonding strength at the interface between the tubing and the cement sheath. The reinforcing cage within the cement-based tubing effectively enhances its tensile and torsional mechanical properties during application.

[0036] Furthermore, the cement-based tubing string is equipped with joints. During well construction, the cement-based tubing string formed after the cement-based tubing string is connected is in a suspended state at the wellhead before cementing. In order to effectively reduce the stress concentration coefficient between the joint and the longitudinal reinforcement and avoid damage at each joint, stress-reinforcing structures are also provided on the joint.

[0037] Furthermore, the joint connection adopts a threaded connection. In order to counteract the increased pre-tightening force when tightening the joint and to avoid the cement-based pipe column from cracking under torque, the longitudinal reinforcement is designed to be at 0° to 15° with the longitudinal direction.

[0038] Furthermore, the longitudinal and circumferential reinforcements are made of iron-based shape memory alloys, which can generate prestress without the need for tensioning, thereby increasing the longitudinal and circumferential tensile strength of the cement-based pipe column.

[0039] In the above-mentioned method for manufacturing cement-based pipe columns provided in the embodiments of the present invention, a prefabricated mold is used. The vortex groove on the inner wall and the spiral texture on the outer wall of the pipe column can be mass-produced using the prefabricated mold. This not only has high efficiency, but also the vortex groove structure and the spiral texture structure are integrated with the cement-based pipe column, resulting in better integrity and lower manufacturing cost.

[0040] In the well construction method using the aforementioned cement-based tubing provided in this embodiment of the invention, cement-based tubing is used for cementing operations after the final drilling operation, while metal casing is still used for cementing operations after subsequent drilling operations. This method can enhance the overall stability of the well depth structure while ensuring efficient and safe gas injection and production, thus optimizing the construction process.

[0041] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0043] Figure 1 This is a schematic diagram of the steel cage structure in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the vortex groove structure on the inner wall of the cement-based pipe column in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the spiral texture structure on the outer wall of the cement-based pipe column in an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the scissor-shaped rib structure in an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the covered cylindrical structure in an embodiment of the present invention;

[0048] Figure 6 This is a flowchart of the preparation method of the cement-based tubular column in an embodiment of the present invention;

[0049] Figure 7 This is a flowchart of a well-drilling method using cement-based tubing in an embodiment of the present invention;

[0050] Figure 8 This is a schematic diagram of a cement-based pipe string structure in an embodiment of the present invention;

[0051] Figure 9 This is a schematic diagram of a well construction project using cement-based tubing in an embodiment of the present invention.

[0052] Explanation of reference numerals in the attached figures:

[0053] 1. Cement-based tubing string; 2. Longitudinal reinforcement; 3. Wrapping reinforcement; 4. Vortex groove; 5. Vortex; 6. High-speed airflow; 7. Spiral texture; 8. Scissor-shaped rib structure; 9. Encased cylindrical structure; 10. Joint; 11. Metal casing; 12. First-stage cementing; 13. Second-stage cementing; 14. Derrick; 15. Lifting device; 16. Drilling platform; 17. Conveyor belt system; 18. Surface; 19. Salt cavern; 20. Interlayer; 21. Cross-section of cement-based tubing string. Detailed Implementation

[0054] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0055] Reference Figures 1 to 5 This invention provides a large-size cement-based tubular string for deep underground space utilization, comprising:

[0056] The steel cage, the ultra-high performance concrete enclosing the steel cage, and the joints 10 connecting the two ends of the steel cage;

[0057] The steel cage includes longitudinal bars 2 and spiral bars 3;

[0058] The inner wall of the cement-based pipe column 1 is provided with multiple vortex grooves 4;

[0059] The outer wall of the cement-based pipe column 1 is provided with a spiral texture 7.

[0060] The cement-based tubing string 1 provided in this invention is applied in deep underground spaces such as various energy storage facilities. It was developed primarily to address a series of drawbacks of traditional injection-production tubing during well construction and use. This cement-based tubing string 1 has at least the following advantages: First, the cement-based tubing string 1 is a reinforced concrete structure. Based on the characteristics of its material, it can reduce the corrosive effect of the gas flowing through the tubing on the inner wall during injection and production. Second, generally, the pressure is higher during gas injection and lower during gas collection. Over time, the gas forms a periodic alternating load on the inner wall of the tubing. Since traditional injection-production tubing is made of metal, it has significant heterogeneity with the cementing material, resulting in large differences in mechanical properties. Therefore, fatigue failure is prone to occur at the connection between the metal injection-production tubing and the cementing material. However, the cement-based tubing string 1, due to its similar material to the cementing material, has better interconnectivity. Good, not easily damaged; third, traditional injection and production pipes need to be installed inside the casing due to construction process requirements, while the cement-based tubing string 1 of this embodiment of the invention is equivalent to simultaneously replacing the traditional injection and production pipe and the outer casing. Therefore, compared with the traditional one, the gas flow area in the cement-based tubing string 1 is larger, which increases the throughput capacity of each well and improves economic efficiency; fourth, the cement-based tubing string 1 has fewer related equipment in the well and a simpler overall structure, so the probability of failure is lower; fifth, considering that the cement-based tubing string 1 is suspended in the well before cementing, the longitudinal reinforcement 2 is set in it to bear the longitudinal tension caused by gravity of the cement-based tubing string 1. Considering that the gas pressure is relatively large during gas injection and production, which may reach tens of megapascals, the winding reinforcement 3 is set in it to enhance the circumferential tensile strength of the inner wall of the tubing string, thereby reducing the tension damage to the inner wall of the pipe caused by gas pressure. Sixth, considering the high gas velocity within the tube column, typically reaching 30 m / s, the high-speed airflow 6 can cause erosion and weathering of the inner wall. Therefore, multiple vortex grooves 4 are installed on the inner wall of the tube column. When the airflow passes through, vortices 5 may be generated within each vortex groove 4, changing the airflow direction and reducing the gas velocity near the inner wall, while the gas velocity far from the inner wall remains unaffected, thus preventing erosion and damage to the inner wall. (Refer to...) Figure 2 For example, the vortex groove 4 can be a concave circular hole, but the shape is not limited in this embodiment of the invention. Seventh, in order to better connect the cement-based tubing string 1 with the cementing cement, a spiral texture 7 can be set on the outer wall of the cement-based tubing string 1. First, the textured structure will definitely increase the bonding area compared with a smooth pipe wall. Second, considering that the cement slurry flows gradually upward from the bottom of the annulus during cementing, a spiral structure is designed along the flow direction of the cement slurry, so that the cement slurry flows upward more evenly along the spiral texture 7, improving the bonding effect. (Refer to...) Figure 3 For example, the spiral texture 7 is in the shape of spiral ridges, but the shape of the spiral texture is not limited in the embodiments of the present invention.

[0061] In one embodiment, the cement-based tubular column 1 further includes a stress-enhancing structure; the stress-enhancing structure is disposed on the joint 10 and is used to share the local stress generated at the connection between the longitudinal reinforcement and the joint 10 during the well construction process of the cement-based tubular column 1.

[0062] The length of the cement-based tubing string 1 is typically between 10 and 12 meters. In well construction projects targeting deep underground spaces, these tubing strings are sequentially connected and lowered into the wellbore. Before cementing, the cement-based tubing string 1 is suspended inside the well; therefore, the potential damage and failure it may face during this process must be considered. Through numerical simulation analysis, it was determined that stress concentration occurs at the connection between the longitudinal reinforcement 2 and the joint 10, meaning that rupture is prone to occur at this stress concentration point. To avoid this adverse effect, a stress-enhancing structure is installed to strengthen the connection between the joint 10 and the longitudinal reinforcement 2, thereby reducing the stress concentration factor.

[0063] Reference Figure 4 In one embodiment, the stress-enhancing structure is a scissor-shaped rib structure 8, which is disposed within the range where the longitudinal rib 2 connects to the joint 10.

[0064] Reference Figure 5 In one embodiment, the stress-enhancing structure is a covered cylindrical structure 9, which is disposed at the end where the longitudinal rib 2 connects to the joint 10.

[0065] The purpose of setting up the stress enhancement structure in this embodiment of the invention is to reduce the stress concentration factor at the stress concentration point, so its structural form is not specifically limited.

[0066] Reference Figure 1 In one embodiment, the longitudinal rib 2 is at a certain preset angle with the longitudinal direction, for example, the preset angle can be 0° to 15°.

[0067] For example, threaded connections are used between the joints 10 of each cement-based pipe column 1. Considering that in order to increase the reliability and tightness of the connection during construction, technicians often need to apply pre-tightening force when tightening the joints 10. Figure 1 The red arrow in the middle indicates the direction of the torque applied when tightening joint 10. To avoid potential damage to the cement-based pipe string formed after the cement-based pipe column 1 is connected due to lack of toughness and insufficient torsional resistance, the direction of the longitudinal reinforcement 2 is adjusted to be 0° to 15° with the longitudinal direction to enhance the torsional resistance of the cement-based pipe string. The specific angle value can be determined based on experience.

[0068] In one embodiment, the longitudinal bars 2 and the spiral bars 3 in the reinforcing cage are made of iron-based shape memory alloy.

[0069] Iron-based shape memory alloy is a shape memory alloy material with iron as the main component. By utilizing the shape memory characteristics of iron-based shape memory alloy, prestress can be generated without the use of tensioning method. Among them, longitudinal reinforcement 2 generates longitudinal prestress, and circumferential reinforcement 3 generates radial prestress, which greatly enhances the longitudinal and circumferential tensile strength of cement-based pipe column 1.

[0070] The cement-based tubular column 1 provided in this embodiment of the invention is cast using ultra-high performance concrete. It possesses high strength, such as compressive strength >180MPa, tensile strength >15MPa, and shear strength >30MPa; and ultra-low permeability, such as permeability <10. -3 (mD); and high corrosion resistance, such as resistance to corrosion from gases such as carbon dioxide, oxygen, and chlorine. Because the ultra-high performance concrete system contains various fibers, its mechanical properties, permeability, and corrosion resistance can be controlled and adjusted according to actual working conditions.

[0071] This invention also provides a method for preparing a large-size well cement-based tubing string 1 for use in deep underground spaces, referring to... Figure 6 The method includes the following steps:

[0072] S61. Prepare a steel cage with iron-based shape memory alloy as reinforcement.

[0073] S62. Connectors are provided at both ends of the steel cage.

[0074] S63. Using a prefabricated mold, ultra-high performance concrete is poured into the mold and cured to form a cement-based pipe column with multiple vortex grooves on the inner wall and spiral texture on the outer wall.

[0075] After step S62 and before step S63, a stress-reinforcing structure is also formed on the joint 10.

[0076] In one embodiment, the stress-enhancing structure may be a scissor rib structure 8, which may be made by welding scissor ribs between each pair of longitudinal bars 2 in the range where the longitudinal bars 2 of the steel cage are connected to the joint 10, and then intersecting these ribs and welding them to the joint 10 in front, thus forming the scissor rib structure 8.

[0077] In one embodiment, the stress-enhancing structure can be a covered cylindrical structure 9, which can be made by welding a columnar covered cylinder with a cross-sectional area larger than that of the longitudinal rib 2 to the end of the longitudinal rib 2 and the outer wall of the joint 10 to form the covered cylindrical structure 9.

[0078] In step S63, a prefabricated mold is used to mass-produce cement-based tubing 1 with inner wall vortex grooves 4 and outer wall spiral textures 7. The inner wall vortex groove 4 structure does not change the inner diameter of the tubing, but forms a large number of small-scale vortices 5 on the inner wall of the tubing, significantly reducing the flow velocity of the airflow near the inner wall of the tubing, effectively preventing the airflow from eroding the tubing wall, while the airflow velocity away from the tubing wall remains unchanged, achieving a balance between erosion prevention and efficient injection and production, ensuring the long-term efficient use of the cement-based tubing 1. The outer wall spiral texture 7 structure significantly increases the roughness and surface area of ​​the outer wall of the tubing, improving the bonding strength between the cement and the outer wall of the tubing. The spiral structure is conducive to the uniform flow and distribution of cement slurry, effectively enhancing the cementing quality and ensuring the long-term integrity of the well barrier. This prefabricated mold has a structure corresponding to the inner wall vortex grooves 4 and the outer wall spiral texture 7 of the cement-based tubing 1. That is to say, the vortex groove 4 structure and the spiral texture 7 structure are integrally formed with the cement-based tubing 1, which not only has good integrity but also low manufacturing cost. After using precast molds and pouring ultra-high strength concrete, for example, high-temperature steam curing is carried out to prestress the longitudinal reinforcement 2 and the spiral reinforcement 3 of the iron-based shape memory alloy, so as to further improve the strength of the cement-based pipe column 1.

[0079] This invention also provides a well construction method using the above-described cement-based tubing string 1, referring to... Figure 7 The method includes the following steps:

[0080] S71. Determine the drilling sequence.

[0081] S72. Conduct drilling operations for each phase and perform corresponding cementing operations using metal casing.

[0082] S73. After the final drilling operation, the cement-based tubing string is connected in sequence and lowered into the well to complete the cementing operation.

[0083] In the well construction method provided in this embodiment of the invention, the cement-based tubing string 1 is used for gas injection. To optimize the construction plan, after the last drilling operation, the cement-based tubing string 1 is used for cementing operations, that is, the cement-based tubing string 1 is used to connect the target layer and the surface 18 for gas injection, while after each previous drilling operation, the metal casing 11 is used for cementing operations (see reference). Figure 8 This ensures efficient and safe gas injection and production, while also leveraging the high rigidity of the metal casing 11 to prevent upper formation collapse and enhance the overall stability of the well depth structure.

[0084] In one embodiment, the connection method for the cement-based tubular column 1 includes threaded connection or welded connection. Both methods can ensure the sealing of each cement-based tubular column 1 at the joint 10.

[0085] In addition, due to the ultra-low permeability of its own material, the cement-based tubing string 1 has good sealing performance. At the same time, after the cement-based tubing string 1 is connected and inserted into the well, cementing is carried out. The cementing cement slurry can serve as a second layer of sealing protection outside the cement-based tubing string, filling any gaps that may exist on the outer wall of the cement-based tubing string, and further increasing the long-term sealing performance of the entire cement-based tubing string.

[0086] In one embodiment, the cement-based pipe strings 1 formed by connecting the cement-based pipe strings 1 during the well construction process have the same inner diameter and the pipe wall thickness gradually decreases from top to bottom.

[0087] Reference Figure 8 Taking two-stage drilling as an example, in order to minimize the flow friction of gas during injection and production, the inner diameter of the entire cement-based tubing string should remain the same. Based on the formation stress distribution and rock mechanics properties, the minimum wall thickness of the cement-based tubing string 1 that meets the long-term stability of the wellbore is determined. Since the cement-based tubing string 1 is suspended at the wellhead before cementing, the tensile force generated by the weight of the cement-based tubing string gradually decreases from top to bottom. Therefore, the wall thickness of the cement-based tubing string is designed to be thicker at the top and thinner at the bottom to minimize the overall weight of the tubing string and achieve the goal of low cost and lightweight design.

[0088] In one embodiment, the tubing connected to the wellhead equipment uses 13Cr stainless steel casing. This is because the wellhead equipment is made of metal, and the first tubing string from top to bottom in the cement-based tubing string uses 13Cr stainless steel casing, which ensures the reliability and safety of the connection to the wellhead equipment while meeting the overall corrosion resistance and sealing requirements of the wellbore.

[0089] In a construction case using the aforementioned cement-based tubing string 1 for well construction, refer to Figure 9 This project is geared towards an air compressed air storage facility. Cement-based tubing strings form the injection-production channel between the underground salt cavern 19 and the surface 18, enabling compressed air injection-production circulation. The well construction system includes a derrick 14, a lifting device 15, a drilling platform 16, and a conveyor belt system 17. The cement-based tubing string 1 is transported within the well site using the conveyor belt system 17, and the lifting and connection processes are completed by the lifting device 15. The joints 10 of the cement-based tubing string 1 are connected using embedded metal threads. Figure 9 The diagram also shows a partially enlarged view of the cross-section 21 of the cement-based tubular column, as well as the structural interlayer 20 in the stratum.

[0090] Reference Figure 8 and Figure 9The well is designed as a two-section structure. In the first section, the well is drilled to 300m, using metal casing 11 with inner and outer diameters of 736.5mm and 628.5mm respectively, and the cementing is returned to the surface 18. In the second section, the well is drilled to 1000m, using cement-based tubing string 1 with inner and outer diameters of 533.4mm and 425.4mm respectively, and the cementing is returned to the surface 18.

[0091] The density of cement-based pipe column 1 is 2.3 g / cm³. 3 The total weight of a single cement-based casing string 1 with a length of 10m and a length of 300m is approximately 79.85t. Assuming no obstruction at the bottom, the tensile stress borne by the casing at the wellhead reaches 4.17MPa. The total weight of a second cement-based casing string 1 with a length of 1000m is approximately 187.00t. Under the same conditions, the tensile stress borne by the cement-based casing string 1 at the wellhead reaches 13.89MPa.

[0092] Practice has proven that cement-based tubing allows for direct injection and production operations within the wellbore after completion, eliminating the need for separate injection and production tubing in traditional underground energy storage facilities. This provides a more economical and reliable process system for well construction and operation in deep underground spaces.

[0093] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A large-size cement-based tubular string for deep underground space utilization, characterized in that, include: The steel cage, the ultra-high performance concrete enclosing the steel cage, and the joints connecting the two ends of the steel cage. The steel cage includes longitudinal bars and spiral bars; The inner wall of the cement-based pipe column is provided with multiple vortex grooves. The outer wall of the cement-based pipe column is provided with a spiral texture.

2. The cement-based tubular column as described in claim 1, characterized in that, Also includes: Stress-reinforced structure; The stress-enhancing structure is installed on the joint to share the local stress generated at the connection between the longitudinal steel bar and the joint during the construction of the cement-based tubular well.

3. The cement-based tubular column as described in claim 2, characterized in that, The stress-enhancing structure is a scissor-shaped rib structure; The scissor-shaped rib structure is located within the area where the longitudinal rib connects to the joint.

4. The cement-based tubular column as described in claim 2, characterized in that, The stress-enhancing structure is a covered cylindrical structure; The covered cylindrical structure is connected to the end of the longitudinal rib.

5. The cement-based tubular column as described in claim 3 or 4, characterized in that, The longitudinal reinforcement is at an angle of 0° to 15° with the longitudinal direction.

6. The cement-based tubular column as described in claim 5, characterized in that, The reinforcing steel used in the steel cage is an iron-based shape memory alloy.

7. A method for preparing a cement-based tubular column as described in any one of claims 1-6, characterized in that, include: Prepare steel cages using iron-based shape memory alloys as reinforcing materials; Joints are provided at both ends of the reinforcing cage; Using prefabricated molds, ultra-high performance concrete is poured into the molds and cured to form cement-based pipe columns with multiple vortex grooves on the inner wall and spiral textures on the outer wall.

8. The preparation method according to claim 7, characterized in that, After the step of setting joints at both ends of the reinforcing cage and before the step of pouring ultra-high performance concrete, the following steps are also included: A stress-reinforcing structure is fabricated on the joint.

9. The preparation method according to claim 8, characterized in that, The stress-enhancing structure is a scissor-shaped rib structure; The rib structure is manufactured in the following manner: Within the connection range between the longitudinal rib and the joint, scissor-shaped ribs are welded between each pair of longitudinal ribs, and the ribs are welded to the joint to form the rib structure.

10. The preparation method according to claim 8, characterized in that, The stress-enhancing structure is a covered cylindrical structure; The covered cylindrical structure is manufactured by the following method: A columnar covering cylinder with a cross-sectional area larger than that of the longitudinal rib is welded to the end of the longitudinal rib and the outer wall of the joint to form the covering cylindrical structure.

11. A well construction method using a cement-based tubing string as described in any one of claims 1-6, characterized in that, include: Determine the drilling sequence; Perform drilling operations in each phase, and use metal casing for corresponding cementing operations; After the final drilling operation, the cement-based tubing is connected in sequence and lowered into the well to complete the cementing operation.

12. The well-drilling method as described in claim 11, characterized in that, The connection methods for the cement-based tubular columns include threaded connection or welded connection.

Images