Construction method of underground rectifying tower

Abstract

The invention provides a construction method of an underground rectifying tower, and belongs to the technical field of rectifying tower construction. The construction method of the underground rectifying tower sequentially comprises the following steps that drilling operation is conducted, a casing pipe floats and sinks into a well, a gap between the inner wall of the well and the casing pipe is filled with slurry, the slurry is solidified, and the rectifying tower is installed in the casing pipe. The sleeve comprises a first straight pipe and a plurality of splicing straight pipes; one end of the first straight pipe is provided with a sealing bottom, and the other end of the first straight pipe is provided with an opening; the step of floating and sinking the casing into the well comprises the steps that liquid is injected into the first straight pipe, so that the first straight pipe extends into the well with mud in the gravity direction, and an opening of the first straight pipe is located outside the well; and then the operation that a splicing straight pipe is welded to the upper end of the first straight pipe and liquid is injected into the splicing straight pipe so that the first straight pipe can sink in the slurry in the gravity direction is repeatedly executed. According to the construction method of the underground rectifying tower, the inclination of the sleeve can be small, so that the perpendicularity index requirement of the rectifying tower is met.

Description

Technical Field

[0001] This application relates to the field of distillation column construction technology, and more specifically, to a method for constructing an underground distillation column. Background Technology

[0002] A distillation column is a tower-type gas-liquid contact device used for distillation. It utilizes the fact that the components in a mixture have different volatility, i.e., different vapor pressures at the same temperature, to transfer lighter components (i.e., low-boiling substances) from the liquid phase to the gas phase, while heavier components (i.e., high-boiling substances) from the gas phase to the liquid phase, thereby achieving separation.

[0003] Most distillation columns are built on the ground using ground support, which results in a large amount of overhead space being occupied. In addition, for distillation columns that are quite tall, those built on the ground have high requirements for earthquake resistance and wind load resistance, making construction and maintenance difficult and costly.

[0004] To solve the above problems, the distillation column can be placed below the ground surface; however, due to the height of the distillation column and the high verticality requirement, it is difficult to reduce the slope of the underground distillation column, and the verticality of the underground distillation column is difficult to meet the requirements. Summary of the Invention

[0005] The purpose of this application is to provide a method for constructing an underground distillation column, which aims to reduce the inclination of the underground distillation column to meet the verticality index requirements of the underground distillation column.

[0006] In a first aspect, this application provides a method for constructing an underground distillation column, comprising the following steps performed sequentially: drilling operations, floating and sinking a casing into the well, filling the gap between the well wall and the casing with slurry, solidifying the slurry, and installing the distillation column inside the casing. The casing includes a first straight pipe and multiple spliced ​​straight pipes; one end of the first straight pipe has a sealed bottom and the other end has an opening, and both ends of the spliced ​​straight pipes have openings; the step of floating and sinking the casing into the well includes: injecting liquid into the first straight pipe, causing the first straight pipe to extend into the well containing mud along the direction of gravity, and ensuring that the opening of the first straight pipe is outside the well; then repeating the operation of welding a spliced ​​straight pipe to the upper end of the first straight pipe and injecting liquid into the spliced ​​straight pipe to cause the first straight pipe to sink in the mud along the direction of gravity.

[0007] In the construction method of the underground distillation column provided in this application, during the process of the casing floating and sinking into the well, the entire casing for placement in the well is formed by welding and splicing straight pipes multiple times. By welding a spliced ​​straight pipe each time, the casing sinks a certain distance in the well along the direction of gravity with the help of gravity buoyancy. This allows the entire casing to sink stably to the bottom of the well along the direction of gravity. This allows the casing placed in the well to have a small inclination, which in turn helps to reduce the inclination of the underground distillation column installed in the casing and can meet the verticality index requirements of the underground distillation column.

[0008] In an optional embodiment of this application, the first straight pipe sinks in the mud at a speed of 3 to 10 m / s along the direction of gravity.

[0009] The above technical solution is beneficial to further reduce the inclination of the casing when it is lowered into the well, and can make the whole process of lowering the casing into the well shorter.

[0010] In an optional embodiment of this application, the lengths of the first straight pipe and the splicing straight pipe are each independently 10 to 50 m.

[0011] The above technical solution is conducive to further reducing the inclination of the casing lowered into the well, which in turn is conducive to further reducing the inclination of the underground distillation column installed in the casing.

[0012] In an optional embodiment of this application, the step of filling the gap between the well wall and the casing with grout includes: first, extending one end of a plurality of grouting pipes into the gap between the well wall and the casing, such that the plurality of grouting pipes are spaced apart around the casing; and then introducing grout into the grouting pipes.

[0013] In the above technical solution, multiple grouting pipes are arranged at intervals around the casing, which helps to avoid uneven grouting into the well wall and casing gap, thus avoiding disturbance to the original mud and casing in the well, and helps to keep the casing lowered into the well at a small inclination.

[0014] Optionally, the number of grouting pipes is 2 to 4.

[0015] Optionally, multiple grouting pipes are arranged at equal intervals around the sleeve.

[0016] In an optional embodiment of this application, each grouting pipe is filled with grout into the gap between the well wall and the casing using a step-by-step grouting method.

[0017] The above technical solution helps to avoid a large change in the density of the liquid phase in the well during the filling of slurry, which would cause a large change in the buoyancy of the casing. It also helps to avoid large disturbances to the casing in the well and helps to keep the casing lowered into the well at a small angle.

[0018] Optionally, the grouting pipe fills the gap between the well wall and the casing with grout in 2 to 4 steps.

[0019] In an optional embodiment of this application, grout is introduced into the grouting pipe while the grouting pipe is pulled up to fill the gap between the well wall and the casing with grout; and during the filling process, the lower end of the grouting pipe is always below the liquid level in the well.

[0020] In the above technical solution, the method of simultaneously lifting the grouting pipe and injecting grout is beneficial to reducing the disturbance of the liquid phase in the well caused by the newly injected grout during grouting, and also to reducing the direct impact disturbance of the newly injected grout on the bottom of the casing, and to keeping the casing lowered into the well at a smaller inclination.

[0021] In an optional embodiment of this application, the drilling operation steps include: first, leveling the ground in the area to be drilled, then drilling a pilot hole in the area to be drilled, and then enlarging the borehole for drilling.

[0022] In the above technical solution, drilling with enlarged boreholes in the pilot hole helps to reduce the well's inclination, which in turn helps to better achieve stable sinking of the casing in the well along the direction of gravity.

[0023] In an optional embodiment of this application, a multi-stage reaming method is used to perform reaming drilling within the pilot hole.

[0024] In the above technical solution, the multi-stage reaming method is used to ream the well in the pilot hole, which helps to reduce the well inclination and thus helps to better achieve the stable sinking of the casing in the well along the direction of gravity.

[0025] Optionally, after drilling, the inner diameter of the upper region of the well is larger than the inner diameter of the middle and lower regions of the well.

[0026] In an optional embodiment of this application, a counterweight and a centralizer are added to the upper end of the drill bit used in drilling during the drilling operation.

[0027] In the above technical solution, adding a counterweight and a stabilizer to the upper end of the drill bit helps to ensure vertical drilling.

[0028] Optionally, the weight of the counterweight is 20 to 80 tons.

[0029] In an optional embodiment of this application, during the drilling operation, the well inclination is measured every 60 to 120 meters of drilling depth; if the well inclination is found to be ≥0.2°, the well is corrected to make the well inclination <0.2°.

[0030] In the above technical solution, the drilling operation adopts the method of drilling and detecting the inclination at the same time, which makes it easy to detect whether the well inclination does not meet the requirements in a timely manner, and thus facilitates timely correction measures for the inclination of the drilled well, thereby helping to reduce the inclination of the well. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A flowchart illustrating the construction method of the underground distillation column provided in this application. Detailed Implementation

[0033] This application provides a method for constructing an underground distillation column, comprising the following steps performed in sequence: drilling operation, floating and sinking the casing into the well, filling the gap between the well wall and the casing with slurry, solidifying the slurry, and installing the distillation column inside the casing.

[0034] The casing includes a first straight pipe and multiple spliced ​​straight pipes; one end of the first straight pipe has a sealed bottom and the other end has an opening, and both ends of the spliced ​​straight pipes have openings.

[0035] The steps for floating and sinking the casing into the well include: injecting fluid into the first straight pipe to extend the first straight pipe into the well containing mud in the direction of gravity, and making the opening of the first straight pipe outside the well; then repeating the operation of welding a spliced ​​straight pipe to the upper end of the first straight pipe and injecting fluid into the spliced ​​straight pipe to make the first straight pipe sink in the mud in the direction of gravity.

[0036] In the construction method of the underground distillation column provided in this application, during the process of the casing floating and sinking into the well, a series of welding and splicing straight pipes are used to form the entire casing for placement in the well. By welding a splicing straight pipe above the well each time and then using the buoyancy of gravity to make the casing sink a certain distance in the direction of gravity, the entire casing can be stably sinked to the bottom of the well in the direction of gravity. This method can stably lower long casings into the well and make the casing lowered into the well have a small inclination (inclination less than 0.2°), which helps to reduce the inclination of the underground distillation column installed in the casing and can meet the verticality index requirements of the underground distillation column.

[0037] Figure 1 For a flowchart of the construction method of the underground distillation column provided in this application, please refer to [link / reference]. Figure 1The construction method for the underground distillation column provided in this application includes the following steps:

[0038] S110, drilling operations are underway.

[0039] Before drilling operations, the location of the well is determined using a theodolite based on the geological survey report and design requirements, and the well structure and related parameters are also determined. If special formations that are prone to collapse or difficult to drill are encountered, methods such as curtain nitrogen injection or curtain grouting can be used to reinforce the formation before drilling operations can proceed.

[0040] After determining the drilling location, a surface area 3 to 10 times the area of ​​the drilling rig is selected as the drilling area. In some optional embodiments of this application, the drilling operation steps include: first, leveling the ground in the drilling area; then, drilling a pilot hole in the drilling area; and finally, enlarging the borehole within the pilot hole. This method, involving enlarging the borehole within the pilot hole, helps reduce the well's inclination (especially for large-diameter wells), thereby facilitating a more stable sinking of the casing along the direction of gravity within the well.

[0041] Furthermore, in some optional embodiments of this application, compared to drilling to the target diameter of the well (i.e., the final diameter of the well) in one go, using a multi-stage reaming method to perform reaming drilling in the pilot hole can improve the drilling accuracy, help reduce the well inclination, and thus help to better achieve stable sinking of the casing in the well along the direction of gravity.

[0042] It is understood that in this application, "using a multi-stage reaming method to perform reaming drilling in the pilot hole" means that the subsequent reaming stage is performed with the diameter of the previous reaming stage as a guide.

[0043] As an example, the multi-stage reaming method can be to perform two, three, four, or five reaming operations in the guide hole; for example, when the multi-stage reaming method of this application is to perform four reaming operations in the guide hole, the diameter of the guide hole can be Φ215.9mm, the diameter of the first-stage reaming can be Φ445mm, the diameter of the second-stage reaming can be Φ720mm, the diameter of the third-stage reaming can be Φ950mm, and the diameter of the fourth-stage reaming can be Φ1200mm.

[0044] In some optional embodiments of this application, after drilling operations, the inner diameter of the upper region of the well is larger than the inner diameter of the middle region and the inner diameter of the lower region of the well. This method helps to avoid well collapse during drilling operations and subsequent casing installation, and improves the safety of drilling operations and subsequent casing installation.

[0045] In this application, the upper region of the well refers to the upper part of the well along the height direction, the middle region of the well refers to the middle part of the well along the height direction, and the lower region of the well refers to the lower part of the well along the height direction.

[0046] As an example, the inner diameter of the upper region of the well can be made larger than that of the middle and lower regions by performing additional reaming in the upper region of the well (i.e., one more reaming operation than in the middle and lower regions of the well).

[0047] Furthermore, in some optional embodiments of this application, when there are easily collapsed strata such as rivers, loose soil, and soft soil in the upper region of the well, drilling operations are first carried out in the upper region of the well, then drilling operations are carried out in the middle region of the well, and finally drilling operations are carried out in the lower region of the well.

[0048] As an example, the drilling operation can proceed as follows: First, boreholes are drilled in the upper region of the well using a reaming drilling method within the pilot hole, ensuring that the inner diameter of the upper region reaches the target inner diameter (i.e., the final diameter of the upper region, for example, Φ1500mm). Then, an anti-collapse fixing pipe with a diameter (for example, Φ1300mm) smaller than the target inner diameter of the upper region is fixed to the inner wall of the upper region. Cement slurry is then used to seal the space between the inner wall of the well and the anti-collapse fixing pipe. After standing for approximately 48 hours, drilling operations are then performed in the middle region of the well, followed by drilling operations in the lower region. This method helps to prevent well collapse during drilling operations and improves the safety of the drilling operation.

[0049] Alternatively, the drilling operation can proceed as follows: First, a Φ1300mm diameter anti-collapse fixing pipe is embedded underground using a vibratory hammer. Then, boreholes are drilled in the upper part of the well using a reaming drilling method within the pilot hole (e.g., drilling to a diameter of Φ1200mm). Next, boreholes are drilled in the middle part of the well, and finally, boreholes are drilled in the lower part. This method helps to prevent well collapse during drilling operations and improves the safety of the drilling operation.

[0050] In some optional embodiments of this application, during the drilling operation, the well inclination is measured every 60 to 120 meters of drilling depth; if the well inclination is found to be ≥0.2°, the well is corrected to make the well inclination <0.2°.

[0051] During drilling operations, the method of simultaneously drilling and checking the well inclination is adopted. This makes it easier to detect in a timely manner whether the well inclination does not meet the requirements, which in turn facilitates timely correction measures for the inclination of the drilled well, thereby helping to reduce the well inclination.

[0052] It should be noted that the well inclination correction process can be carried out using conventional well deviation correction operations; as an example, the well inclination correction process can be carried out using a screw-type composite directional drilling tool.

[0053] In other feasible embodiments of this application, a high-precision inclinometer can be used to detect the top and azimuth angles of the borehole. If the borehole top angle is found to be out of range, a screw-type composite directional drilling tool can be used to correct the inclination in a timely manner to prevent the bottom coordinates of the borehole from deviating from the design target point, so as to ensure that the verticality of the well meets the index requirements.

[0054] In some optional embodiments of this application, a counterweight and a centralizer are added to the upper end of the drill bit during drilling operations. This method, by adding a counterweight and a centralizer to the upper end of the drill bit, helps ensure vertical drilling.

[0055] Furthermore, the weight of the counterweight is 20 to 80 tons.

[0056] Furthermore, the size of the stabilizer is between the size of the drill bit and the size of the borehole.

[0057] It should be noted that during the drilling operation of this application, reaming can be performed solely using a multi-stage reaming method within the pilot hole, or simply by adding a counterweight and centralizer to the upper end of the drill bit, or a combination of both. Compared to reaming solely using a multi-stage reaming method within the pilot hole, or simply by adding a counterweight and centralizer to the upper end of the drill bit, the combination of "multi-stage reaming within the pilot hole" and "adding a counterweight and centralizer to the upper end of the drill bit" is more conducive to reducing well inclination.

[0058] It should be noted that in other optional embodiments of this application, the operation of drilling the pilot hole may not be specifically limited, and a conventional drilling machine with a guiding device can be used.

[0059] To further prevent the risk of well collapse during drilling, large-diameter mud wall protection technology can be adopted. For example, a drilling fluid system with medium to high specific gravity, high viscosity, and low water loss can be used. Then, conventional drilling fluid inhibitors are added to the drilling fluid system. During the drilling process, the specific gravity, sand content, colloid content, and viscosity of the mud are monitored in real time according to the cuttings return situation. The mud performance is adjusted and performance maintenance is strengthened to form a large-diameter anti-collapse system.

[0060] S120, the casing floated and sank into the well.

[0061] In this application, the sleeve includes a first straight tube and a plurality of spliced ​​straight tubes; one end of the first straight tube has a sealed bottom and the other end has an opening, and both ends of the spliced ​​straight tubes have openings.

[0062] It should be noted that in this application, a first straight pipe and multiple spliced ​​straight pipes are welded together to form a casing for floating and sinking into the well. One end of the casing has an opening and the other end has a sealed bottom. The inner diameter of the first straight pipe is the same as the inner diameter of the spliced ​​straight pipes, and the outer diameter of the first straight pipe is the same as the outer diameter of the spliced ​​straight pipes. The sealed bottom and the opening of the first straight pipe are located at opposite ends of the first straight pipe's axial direction, and the inner diameter of the sealed bottom of the first straight pipe is the same as the inner diameter of the opening of the first straight pipe, and the outer diameter of the sealed bottom of the first straight pipe is the same as the outer diameter of the opening of the first straight pipe. The two openings of the spliced ​​straight pipe are located at opposite ends of the spliced ​​straight pipe's axial direction, and the inner diameter and outer diameter of the two openings of the spliced ​​straight pipe are the same.

[0063] It should be noted that this application does not limit the material of the first straight pipe and the splicing straight pipe. For example, the first straight pipe and the splicing straight pipe can be carbon steel pipe and stainless steel pipe.

[0064] It should be noted that after the welding of the spliced ​​straight pipes is completed, this application performs negative pressure helium leak detection and 100% X-ray inspection. Only after the test results are deemed qualified can the subsequent welding of the spliced ​​straight pipes be carried out, thereby ensuring the structural stability and sealing of the entire casing.

[0065] In this application, the steps of floating and sinking the casing into the well include: injecting fluid into the first straight pipe to extend the first straight pipe into the well containing mud along the direction of gravity, such that the opening of the first straight pipe is located outside the well and the bottom seal of the first straight pipe is located inside the well; and then repeating the operation of welding a spliced ​​straight pipe at the upper end of the first straight pipe and injecting fluid into the spliced ​​straight pipe to make the first straight pipe sink in the mud along the direction of gravity.

[0066] In each instance of welding and splicing straight pipes, the upper end of the pipe body that has been welded to form a casing is located above the wellhead.

[0067] Understandably, repeatedly performing the operations of "welding a spliced ​​straight pipe to the upper end of the first straight pipe" and "injecting liquid into the spliced ​​straight pipe so that the first straight pipe sinks in the mud along the direction of gravity" means that: each time a spliced ​​straight pipe is welded, only one spliced ​​straight pipe is welded at the upper end of the first straight pipe (i.e., the upper end of the pipe body that has been welded into a sleeve); after welding one spliced ​​straight pipe, liquid is immediately injected into the welded spliced ​​straight pipe so that the injected liquid flows down in the welded sleeve under gravity. The increased liquid phase inside the casing causes the weight of the casing to exceed the buoyancy, resulting in the first straight pipe sinking in the well mud along the direction of gravity. This sinks the casing body along with the first straight pipe. When the upper end of the casing body has descended a certain distance and is still above the wellhead, another spliced ​​straight pipe is welded at the upper end of the casing body. Liquid is then injected into the spliced ​​straight pipe, and the above operation is repeated until all the spliced ​​straight pipes are welded.

[0068] As an example, the liquid phase injected into the first straight pipe or the spliced ​​straight pipe can be pure water. Before each welding of the spliced ​​straight pipe, the upper end of the pipe body that has been welded into a casing is fixed using a fixing device, so that the upper end of the pipe body that has been welded into a casing is above the wellhead; the spliced ​​straight pipe to be welded is lifted using a crane and moved above the pipe body that has been welded into a casing before the welding of the spliced ​​straight pipe is carried out.

[0069] It should be noted that this application does not limit the specific method of welding and splicing straight pipes. For example, multiple sites can be welded symmetrically to reduce material deformation.

[0070] In some optional embodiments of this application, after each welded spliced ​​straight pipe, the first straight pipe sinks in the mud at a speed of 3-10 m / s along the direction of gravity. This is beneficial for further reducing the inclination of the casing placed in the well and can shorten the time required for the entire process of placing the casing in the well. If the sinking speed is too fast, it may disturb the mud in the well and may cause the risk of well collapse. If the sinking speed is too slow, the entire process of placing the casing in the well will take a long time, which is not conducive to improving construction efficiency.

[0071] As an example, after each welded splice of straight pipe, the velocity at which the first straight pipe sinks in the slurry along the direction of gravity can be any value among 3m / s, 4m / s, 5m / s, 6m / s, 7m / s, 8m / s, 9m / s, and 10m / s, or any value between the two.

[0072] Furthermore, in some optional embodiments of this application, after each welded splice of straight pipe, the first straight pipe sinks in the mud at a speed of 4 to 6 m / s along the direction of gravity.

[0073] In some optional embodiments of this application, the lengths of the first straight pipe and the spliced ​​straight pipe are each independently 10-50m; this is beneficial to further reduce the inclination of the casing lowered into the well, and thus further reduce the inclination of the underground distillation column installed in the casing; if the length of the first straight pipe or the spliced ​​straight pipe is long, the operation of lowering the first straight pipe or welding the spliced ​​straight pipe each time may be more complicated and difficult; if the length of the spliced ​​straight pipe is short, it will result in more welding times for the casing, leading to longer welding time, which is not conducive to improving construction efficiency, and may also result in larger welding errors due to more welding times, thus affecting the verticality of the casing itself.

[0074] As an example, the lengths of the first straight pipe and the splicing straight pipe can each be independently any one of 10m, 15m, 20m, 25m, 30m, 35m, 40m, 45m and 50m or any range between the two.

[0075] In some optional embodiments of this application, multiple reinforcing members are spaced apart on the outer wall of the sleeve along its length. The inclusion of these reinforcing members improves the structural strength of the sleeve and helps prevent deformation that could affect its perpendicularity.

[0076] It should be noted that this application does not limit the firmware; conventional firmware can be used.

[0077] Furthermore, in some optional embodiments of this application, the distance between two adjacent reinforcement components is 50 to 80 m.

[0078] As an example, the distance between two adjacent reinforcement components can be any value among 50m, 55m, 60m, 65m, 70m, 75m and 80m or a range between any two.

[0079] S130, fill the gap between the well wall and the casing with slurry, and then solidify the slurry.

[0080] In some optional embodiments of this application, the step of filling the gap between the well wall and the casing with grout includes: first, extending one end of a plurality of grouting pipes into the gap between the well wall and the casing, such that the plurality of grouting pipes are spaced apart around the casing; and then introducing grout into the grouting pipes.

[0081] When filling the grout, multiple grouting pipes are arranged at intervals around the casing. This helps to avoid uneven grouting into the well wall and casing gaps, which would disturb the original mud and casing in the well. It also helps to keep the casing lowered into the well at a smaller angle.

[0082] Furthermore, in some optional embodiments of this application, the number of grouting pipes is 2 to 4.

[0083] For example, the number of grouting pipes can be 2, 3 or 4.

[0084] In some optional embodiments of this application, multiple grouting pipes are arranged at equal intervals around the casing; this helps to further avoid uneven grouting into the well wall and casing gap, which would disturb the original mud and casing in the well, and helps to keep the casing lowered into the well at a smaller inclination.

[0085] In some optional embodiments of this application, each grouting pipe is filled with grout in stages into the gap between the well wall and the casing. Since the grout used for filling is used to stabilize the casing after subsequent curing, the density of the grout used for filling is often greater than that of the drilling mud (i.e., the drilling mud and the original underground mud). This method helps to avoid a sudden and large change in the density of the liquid phase in the well when filling the well with grout all at once, which would cause a sudden and large change in the buoyancy of the casing. It also helps to avoid large disturbances to the casing in the well and helps to maintain a small inclination of the casing when it is lowered into the well.

[0086] Furthermore, in some optional embodiments of this application, the grouting pipe fills the gap between the well wall and the casing in 2 to 4 steps; this helps to further maintain a smaller inclination of the casing lowered into the well.

[0087] As an example, the number of steps in which each grouting pipe fills the gap between the well wall and the casing with grout can be 2, 3, or 4.

[0088] In some optional embodiments of this application, grout is introduced into the grouting pipe while the grouting pipe is pulled up, and grout is filled into the gap between the well wall and the casing until the grout overflows outside the well and the grout is stopped; and during the grout filling process, the lower end of the grouting pipe is always below the liquid level in the well.

[0089] Using the method of simultaneously lifting the grouting pipe and injecting grout helps to reduce the disturbance of the liquid phase in the well caused by the newly injected grout, and also helps to reduce the direct impact disturbance of the newly injected grout on the bottom of the casing. This helps to avoid the risk of collapse in the well and also helps to keep the casing sinking into the well at a small inclination.

[0090] Furthermore, in some optional embodiments of this application, before filling the grout, one end of a plurality of grouting pipes is inserted into the gap between the well wall and the casing, such that the lower end of the grouting pipe is located at the bottom of the well.

[0091] It should be noted that in other optional embodiments of this application, the grouting pipe is introduced into the well wall and the casing while the grouting pipe is pulled up, and the grouting is filled into the gap between the well wall and the casing until the grout overflows out of the well and the grouting is stopped; and during the filling process, the lower end of the grouting pipe can also be located above the liquid surface in the well.

[0092] It should be noted that this application does not limit the grout material introduced into the grouting pipe; conventional reinforcing cement grout or concrete grout can be used.

[0093] In some optional embodiments of this application, after grouting, after the grout has naturally solidified for 18 to 24 hours, observe whether the height of the upper surface of the solidified grout in the well has decreased. If the height of the upper surface of the solidified grout in the well has decreased, continue to perform the aforementioned operation of "filling the gap between the well wall and the casing with grout and then solidifying the grout" until the height of the upper surface of the solidified grout in the well no longer decreases after the grout has naturally solidified for 18 to 24 hours.

[0094] S140, a distillation column is installed inside the casing.

[0095] In this application, the liquid phase inside the casing needs to be drained before installing the distillation column inside the casing.

[0096] It should be noted that this application does not limit the specific operation of installing the distillation column inside the casing; conventional methods can be used. This application also does not specifically limit the distillation column; for example, the distillation column can be a plate distillation column or a packed distillation column, etc. This application also does not limit the height of the distillation column; for example, the height of the distillation column can be 150 to 300 m.

[0097] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for constructing an underground distillation column, characterized in that, The process includes the following steps performed in sequence: drilling operations, floating and sinking the casing into the well, filling the gap between the well wall and the casing with slurry, solidifying the slurry, and installing a distillation column inside the casing; The sleeve includes a first straight tube and a plurality of spliced ​​straight tubes; one end of the first straight tube has a sealed bottom and the other end has an opening, and both ends of the spliced ​​straight tubes have openings; The steps of floating and sinking the casing into the well include: injecting fluid into the first straight pipe to extend the first straight pipe into the well containing mud in the direction of gravity, and making the opening of the first straight pipe located outside the well; and then repeating the operations of welding a spliced ​​straight pipe to the upper end of the first straight pipe and injecting fluid into the spliced ​​straight pipe to make the first straight pipe sink in the mud in the direction of gravity.

2. The construction method of the underground distillation column according to claim 1, characterized in that, The first straight pipe sinks in the mud at a speed of 3 to 10 m / s along the direction of gravity.

3. The construction method of the underground distillation column according to claim 1, characterized in that, The lengths of the first straight pipe and the spliced ​​straight pipe are each independently 10 to 50 m.

4. The method for constructing an underground distillation column according to any one of claims 1 to 3, characterized in that, The step of filling the gap between the well wall and the casing with grout includes: first, extending one end of a plurality of grouting pipes into the gap between the well wall and the casing, such that the plurality of grouting pipes are spaced apart around the casing; then, introducing the grout into the grouting pipes. Optionally, the number of grouting pipes is 2 to 4; Optionally, a plurality of the grouting pipes are arranged at equal intervals around the casing.

5. The construction method of the underground distillation column according to claim 4, characterized in that, Each of the grouting pipes is filled with grout in a step-by-step grouting manner into the gap between the well wall and the casing; Optionally, the grouting pipe fills the gap between the well wall and the casing with grout in 2 to 4 steps.

6. The construction method of the underground distillation column according to claim 4, characterized in that, The grout is introduced into the grouting pipe while the grouting pipe is pulled up, and the grout is used to fill the gap between the well wall and the casing with the grout. During the filling process, the lower end of the grouting pipe is always below the liquid level in the well.

7. The method for constructing an underground distillation column according to any one of claims 1 to 3, characterized in that, The drilling operation includes the following steps: first, leveling the ground in the area to be drilled; then, drilling a pilot hole in the area to be drilled; and then enlarging the borehole for drilling.

8. The construction method of the underground distillation column according to claim 7, characterized in that, The reaming drilling is performed in the pilot hole using a multi-stage reaming method. Optionally, after the drilling operation, the inner diameter of the upper region of the well is larger than the inner diameter of the middle and lower regions of the well.

9. The method for constructing an underground distillation column according to any one of claims 1 to 3, characterized in that, During the drilling operation, a counterweight and a stabilizer are added to the upper end of the drill bit used for drilling. Optionally, the weight of the counterweight is 20 to 80 tons.

10. The method for constructing an underground distillation column according to any one of claims 1 to 3, characterized in that, During the drilling operation, the inclination of the well is measured every 60 to 120 meters of drilling depth. If the inclination of the well is found to be ≥0.2°, the well is corrected to make the inclination <0.2°.

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