Geothermal well pipe column and construction process

Abstract

This invention belongs to the field of geothermal development technology, specifically relating to a geothermal well string and its construction process. The geothermal well string includes: a surface casing with a first load-bearing short section; a secondary casing with a first mounting ring on its outer wall for fitting the first load-bearing short section, and a second load-bearing short section located below the first mounting ring; and a tailpipe assembly with a second mounting ring on its outer wall for fitting the second load-bearing short section. This invention can reduce costs and improve construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of geothermal development technology, specifically relating to a geothermal well string and a geothermal well construction process. Background Technology

[0002] Geothermal resource extraction is a rapidly emerging new energy technology in recent years. Geothermal wells often adopt a three-section structure of guide pipe + technical casing + tailpipe (screen pipe). Unlike conventional oil and gas tailpipe well cementing construction, geothermal wells require simple, efficient and low-cost tailpipe cementing tools and cementing construction technology due to cost and drilling efficiency considerations during development. Summary of the Invention

[0003] To address the technical problems described above, this invention aims to provide a geothermal well string and construction process that can reduce costs and improve construction efficiency.

[0004] According to the present invention, a geothermal well string is provided, comprising: Surface sleeve, on which a first load-bearing short section is provided; A technical sleeve is provided with a first mounting ring on the outer wall of the technical sleeve for fitting with the first bearing short section, and a second bearing short section is provided on the technical sleeve, the second bearing short section being located below the first mounting ring; The tailpipe assembly has a second seat ring on its outer wall for fitting with the second load-bearing section.

[0005] In one specific embodiment, the first seat ring and the second seat ring are constructed in annular shape, and a limiting step is provided on the inner wall of the first bearing section to axially abut against the first seat ring; a limiting step is provided on the inner wall of the second bearing section to axially abut against the second seat ring.

[0006] In one specific embodiment, the technical sleeve includes a connector, the second load-bearing short section is coaxially disposed below the connector, and the first seat ring is coaxially disposed on the outer wall of the connector.

[0007] In one specific embodiment, the tailpipe assembly includes a guide shoe, a screen tube string, a suspension body, and a setting seal assembly arranged coaxially from bottom to top. The second setting ring is coaxially disposed on the outer wall of the suspension body. The setting seal assembly is configured to seal the annular space between the tailpipe assembly and the technical sleeve.

[0008] In one specific embodiment, the setting assembly includes: A rubber sleeve coaxially mounted on the outer wall of the suspension body; A movable cylinder is coaxially mounted on the outer wall of the suspension body, and the movable cylinder is located above the rubber cylinder; An activation component is configured to move the movable cylinder downward relative to the suspension body, thereby axially compressing the rubber cylinder and causing the rubber cylinder to expand radially.

[0009] In one specific embodiment, the activation component includes a setting short section coaxially disposed within the movable cylinder, and a setting stop block is disposed on the outer wall of the setting short section, the setting stop block being elastic enough to open radially outward.

[0010] In one specific embodiment, in the initial state, the setting short section is sleeved inside the movable cylinder, and the setting stop is in a retracted state; Lifting the setting section allows it to move out from the upper end of the moving cylinder, the setting block opens radially, and then pressing the setting section down causes the setting block to push the moving cylinder axially downward, thereby axially compressing the rubber tube to complete the setting.

[0011] In one specific embodiment, the tailpipe assembly includes, from bottom to top, a guide shoe, a screen pipe string, a cement umbrella, a swirl section, a three-section float hoop, and a suspension body, all coaxially arranged. The second seat ring is coaxially arranged on the outer wall of the suspension body.

[0012] In one specific embodiment, the swirl sub includes a swirl sub body, and a swirl hole is provided on the side wall of the swirl sub body, the central axis of the swirl hole being inclined to the radial direction of the swirl sub body.

[0013] In one specific embodiment, a blind flange short section is provided below the swirl short section, the blind flange short section being configured to block the tubing.

[0014] According to the present invention, a geothermal well construction process is also provided, comprising: The surface casing with the first load-bearing short section is lowered into the well; A technical casing equipped with a first mounting ring and a second load-bearing short section is lowered into the well, so that the first mounting ring is mounted on the first load-bearing short section, and the technical casing is cemented using the internal insertion method. The tailpipe assembly equipped with the second mounting ring is lowered into the well, so that the second mounting ring sits on the second bearing short section, and the annulus between the tailpipe assembly and the technical casing is sealed by the setting seal assembly.

[0015] According to the present invention, a geothermal well construction process is also provided, comprising: The surface casing with the first load-bearing short section is lowered into the well; A technical casing equipped with a first mounting ring and a second load-bearing short section is lowered into the well, so that the first mounting ring is mounted on the first load-bearing short section, and the technical casing is cemented using the internal insertion method. The tailpipe assembly equipped with the second mounting ring is lowered into the well, so that the second mounting ring sits on the second bearing short section, and the tailpipe assembly is cemented by the swirl short section.

[0016] Compared with the prior art, this application has at least the following advantages.

[0017] This invention proposes a geothermal well tubing string that uses a load-bearing short section and a set ring to insert the technical casing and tailpipe assembly, thereby improving cementing quality and operational efficiency while reducing operating costs.

[0018] The present invention also proposes a geothermal well construction process, which includes a geothermal well tubing string that can improve the construction efficiency of geothermal wells. Attached Figure Description

[0019] The invention will now be described with reference to the accompanying drawings.

[0020] Figure 1 A schematic diagram of an embodiment of a geothermal well string according to the present invention is shown, in which the positional relationship of the surface casing, the technical casing and the tailpipe assembly is shown only schematically. Figure 2 A schematic diagram of one embodiment of the technical sleeve according to the present invention is shown; Figure 3 A schematic diagram of one embodiment of the tailpipe assembly according to the present invention is shown; Figure 4 A schematic diagram of another embodiment of the tailpipe assembly according to the present invention is shown.

[0021] The reference numerals in the figure are as follows: 100. Surface casing; 101. First load-bearing sub; 200. Technical casing; 201. First set ring; 202. Second load-bearing sub; 203. Connector; 210. First feed tool; 300. Tailpipe assembly; 301. Second set ring; 302. Guide shoe; 303. Screen string; 304. Suspension body; 305. Setting assembly; 3050. Activation assembly; 3051. Rubber sleeve; 3052. Moving sleeve; 3053. Setting sub; 3054. Setting stop block; 306. Blind flange sub; 307. Swirl sub; 3071. Swirl sub body; 3072. Swirl hole; 308. Three-section float collar; 309. Cement umbrella; 310. Second feed tool; 311. Tailpipe rubber plug; 312. Drill pipe rubber plug; 1000. Geothermal well string.

[0022] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0023] The invention will now be described with reference to the accompanying drawings.

[0024] It should be noted that in this application, the direction near the inlet after the geothermal well string according to the present invention is described as "upper" or a similar term, i.e. Figure 1 Above; while the direction away from the wellhead after the geothermal well string is inserted is described as "below" or similar, i.e. Figure 1 Below.

[0025] Figure 1 The structure of a geothermal well string 1000 according to the present invention is shown. For example... Figure 1 As shown, the geothermal well tubing string 1000 includes a surface casing 100, a technical casing 200, and a tailpipe assembly 300.

[0026] A first support section 101 is provided at the lower part of the outer sleeve 100. The outer diameter of the technical sleeve 200 is smaller than the inner diameter of the outer sleeve 100. A first mounting ring 201 for fitting the first support section 101 is provided on the upper outer wall of the technical sleeve 200. A second support section 202 is provided at the lower part of the technical sleeve 200, located below the first mounting ring 201. The outer diameter of the tailpipe assembly 300 is smaller than the inner diameter of the technical sleeve 200. A second mounting ring 301 for fitting the second support section 202 is provided on the upper outer wall of the tailpipe assembly 300.

[0027] The process of constructing the geothermal well string 1000 is as follows: First, the surface casing 100 is lowered. Then, the technical casing 200 is lowered, with the first mounting ring 201 on the technical casing 200 axially overlapping the first bearing short section 101, achieving fixed-point mounting of the technical casing 200. Next, the tailpipe assembly 300 is lowered, with the second mounting ring 301 on the tailpipe assembly 300 axially overlapping the second bearing short section 202, achieving fixed-point mounting of the technical casing 200. By setting the mounting ring and bearing short section to achieve fixed-point mounting of the technical casing and tailpipe assembly, compared to the existing technology using conventional hydraulic tailpipe hangers, the steps of ball-throwing and pressure-pressurizing for tailpipe hanger mounting are eliminated, saving the operational steps of ball throwing, ball delivery, pressure-pressurizing, and ball seat clearance. This simplifies operation, reduces technical costs, and eliminates the need for ball seats in the string structure.

[0028] In one embodiment, both the first seat ring 201 and the second seat ring 301 are constructed in annular shape. The first seat ring 201 is coaxially fixedly disposed on the outer wall of the technical sleeve 200, which is equivalent to providing an annular protrusion on the outer wall of the technical sleeve 200. The second seat ring 301 is coaxially fixedly disposed on the outer wall of the tailpipe assembly 300, which is equivalent to providing an annular protrusion on the outer wall of the tailpipe assembly 300. A limiting step capable of axially abutting the first seat ring 201 is provided on the inner wall of the first support segment 101, and a limiting step capable of axially abutting the second seat ring 301 is provided on the inner wall of the second support segment 202. Further, the lower end of the first seat ring 201 is constructed as a slope. When the first seat ring 201 axially abuts the first support segment 101, the first support segment 101 contacts the slope of the first seat ring 201, thereby enabling the first support segment 101 to provide a radially inward pressure to the first seat ring 201. Similarly, the lower end of the second seat ring 301 is constructed as an inclined surface. When the second seat ring 301 axially abuts against the second bearing short section 202, the second bearing short section 202 contacts the inclined surface of the second seat ring 301, thereby enabling the second bearing short section 202 to provide a radially inward pressure to the second seat ring 301.

[0029] In a specific embodiment, such as Figure 2 As shown, the technical sleeve 200 includes a connector 203 and a second load-bearing short section 202 (as shown). Figure 4 As shown, the first seat ring 201 is coaxially disposed below the connector 203 and on the outer wall of the connector 203.

[0030] In one embodiment, the technical casing 200 is inserted into the well via a first insertion tool 210. Specifically, the technical casing 200 includes, from bottom to top, a two-part float shoe, a two-part float collar, an insert float collar (not shown), a second load-bearing sub 202, and a connector 203, all coaxially arranged. When the technical casing 200 is inserted into the well, the upper end of the connector 203 is coaxially and fixedly connected to the first insertion tool 210. After the technical casing 200 is inserted into position (the first seat ring 201 axially abuts against the first load-bearing sub 101) by the first insertion tool 210, the first insertion tool 210 presses down, increasing the friction between the first seat ring 201 and the first load-bearing sub 101. By rotating the first insertion tool 210 forward, the first insertion tool 210 rotates relative to the connector 203, thus releasing the first insertion tool 210 from the connector 203. Then, the first insertion tool 210 is withdrawn. Afterwards, the cementing drill pipe and insert head are lowered. The insert head can work with the insert-type float collar of the technical casing 200 to complete the internal cementing operation. The cement slurry enters directly into the annulus between the technical casing 200 and the wellbore through the cementing drill pipe, insert head, and insert-type float collar, avoiding the generation of slurry mixing in the technical casing 200. The use of volume replacement eliminates the need to put in cementing plugs, reducing the time for drilling and removing cement plugs and accessory cores, improving construction efficiency, and improving cementing quality.

[0031] It is easy to understand that the specific structure of the first insertion tool 210 is well known to those skilled in the art, as are the specific structures of the insertion head and the insertion float, and the internal cementing operation performed through the insertion head and the insertion float. These will not be described in detail here.

[0032] By using a mounting ring and a load-bearing short section to achieve fixed-point mounting of the tailpipe, compared to the current construction using conventional hydraulic tailpipe hangers in the second phase, the steps of throwing a ball and pressurizing to mount the tailpipe hanger are eliminated. This saves the operation steps of throwing, feeding, pressurizing, and clearing the ball seat, making the operation simple and reducing technical costs. There is no need to place a ball seat in the pipe string structure. Cement is only present in the casing below the float hoop, which can effectively reduce the length of cement plug in the casing and save drilling time.

[0033] In one embodiment of the present invention, the tailpipe assembly 300 includes a guide shoe 302, a screen tube string 303, a suspension body 304 and a setting seal assembly 305 arranged coaxially from bottom to top, a second setting ring 301 is coaxially arranged on the outer wall of the suspension body 304, and the setting seal assembly 305 is configured to seal the annular space between the tailpipe assembly 300 and the technical sleeve 200.

[0034] like Figure 4 As shown, in a specific embodiment, the setting assembly 305 includes a glue tube 3051, a moving tube 3052, and an activation assembly 3050.

[0035] The rubber sleeve 3051 is coaxially mounted on the outer wall of the suspension body 304, and the lower end of the rubber sleeve 3051 is axially abutting against the suspension body 304, so that the lower end of the rubber sleeve 3051 cannot move downward relative to the suspension body 304.

[0036] The movable cylinder 3052 is coaxially mounted on the outer wall of the suspension body 304. The movable cylinder 3052 is located above the rubber cylinder 3051. The lower end of the movable cylinder 3052 axially abuts against the upper end of the rubber cylinder 3051, and the upper end of the movable cylinder 3052 is located above the upper end face of the suspension body 304.

[0037] The activation component 3050 is configured to move the movable cylinder 3052 downward relative to the suspension body 304, thereby axially compressing the rubber cylinder 3051 and causing the rubber cylinder 3051 to expand radially, thereby sealing the annular space between the suspension body 304 of the tailpipe assembly 300 and the connector 203 of the technical sleeve 200.

[0038] In one embodiment, the activation component 3050 includes a setting section 3053 and setting blocks 3054. The setting section 3053 is cylindrical and coaxially disposed within a movable cylinder 3052. A plurality of setting blocks 3054 are spaced apart circumferentially on the outer side of the setting section 3053, and the setting blocks 3054 are elastic, allowing them to open radially outward. In the initial state, the setting section 3053 is positioned within the movable cylinder 3052 by shear pins, and the outer wall of the setting blocks 3054 contacts the inner wall of the movable cylinder 3052. At this time, the movable cylinder 3052 restricts the radial opening of the setting blocks 3054, and the setting blocks 3054 are in a retracted state. When radial expansion of the rubber sleeve 3051 is required, the setting short section 3053 is pressed down to cut the shear pin between the setting short section 3053 and the moving cylinder 3052. Then, the setting short section 3053 is lifted up to move it out from the upper end of the moving cylinder 3052 until the setting stop block 3054 is released from the restriction of the moving cylinder 3052. At this time, the setting stop block 3054 opens radially under its own elastic force until its outer diameter is larger than the inner diameter of the moving cylinder 3052. Then, the setting short section 3053 is pressed down to push the moving cylinder 3052 axially downward, cutting the shear pin between the moving cylinder 3052 and the suspension body 304. This causes the moving cylinder 3052 to move downward relative to the suspension body 304, axially compressing the rubber sleeve 3051 to complete the setting and prevent mud and sand from entering the wellbore from above the rubber sleeve 3051, thus completing the construction of the geothermal well string 1000.

[0039] With this setup, the entire installation process of the tailpipe assembly 300 does not require pressurization. The installation of the tailpipe assembly 300 can be completed simply by lifting and pressing up, which can effectively reduce tool procurement costs, simplify operation, and reduce technical difficulty.

[0040] According to the present invention, in an embodiment of a geothermal well string 1000 provided with a setting assembly 305, the geothermal well construction process is as follows.

[0041] The surface casing 100 was lowered into the well.

[0042] Then, the technical sleeve 200 is lowered in, so that the first mounting ring 201 on the technical sleeve 200 axially overlaps the first bearing short section 101, realizing the fixed mounting of the technical sleeve 200. After the technical sleeve 200 is delivered into place by the first feeding tool 210 (the first mounting ring 201 axially abuts against the first bearing short section 101), the first feeding tool 210 is pressed down to increase the friction between the first mounting ring 201 and the first bearing short section 101. By rotating the first feeding tool 210 in the forward direction, the first feeding tool 210 is rotated relative to the connecting body 203, so that the first feeding tool 210 is released from the connecting body 203. Then, the first feeding tool 210 is pulled out. Afterwards, the cementing drill pipe and insert head are lowered. The insert head can work with the insert-type float collar of the technical casing 200 to complete the internal cementing operation. The cement slurry enters directly into the annulus between the technical casing 200 and the wellbore through the cementing drill pipe, insert head, and insert-type float collar, avoiding the generation of slurry mixing in the technical casing 200. The use of volume replacement eliminates the need to put in cementing plugs, reducing the time for drilling and removing cement plugs and accessory cores, improving construction efficiency, and improving cementing quality.

[0043] Then, the tailpipe assembly 300 is lowered in, so that the second mounting ring 301 of the tailpipe assembly 300 is axially overlapped on the second bearing short section 202, thereby realizing the fixed mounting of the technical sleeve 200. Then, the setting short section 3053 is pressed down to cut the shear pin between the setting short section 3053 and the moving cylinder 3052. Then, the setting short section 3053 is lifted up to move it out from the upper end of the moving cylinder 3052 until the setting block 3054 is freed from the restriction of the moving cylinder 3052. At this time, the setting block 3054 opens radially under its own elastic force until its outer diameter is larger than the inner diameter of the moving cylinder 3052. Then, the setting short section 3053 is pressed down to push the moving cylinder 3052 axially downward, cutting the shear pin between the moving cylinder 3052 and the suspension body 304. This causes the moving cylinder 3052 to move downward relative to the suspension body 304, axially compressing the rubber sleeve 3051 to complete the setting and prevent mud and sand from entering the wellbore from above the rubber sleeve 3051, thus completing the construction of the geothermal well string 1000.

[0044] According to the present invention, another embodiment of the tailpipe assembly 300 is also provided. Top-cemented screen pipe completion technology is a completion process applied to horizontal or highly deviated wells. Due to its simplicity and ease of operation, it is widely used in major oilfields, effectively improving the situation of cross-contamination between external annulus cells and providing conditions for perforation development of the oil layer in the transition section at the top of the screen pipe and reliable sealing of the water layer in the transition section. Currently, the commonly used top-cemented screen pipe completion string (from bottom to top) is: guide shoe + screen pipe string + blind plate + hydraulic expansion packer + two-stage cementing device + casing string + tailpipe suspension body + drill string. Above the blind plate, a closed pressure "dead cavity" is formed inside the pipe in this completion string. During the running-in process, the vibration of the fluid column inside the pipe can easily lead to problems such as premature opening of the stage collar and premature expansion of the external packer.

[0045] To address the aforementioned issues, this invention proposes a tailpipe assembly 300, which replaces the staged cement injector with a swirl short section 307, replaces the hydraulic expansion seal packer with a second seat ring 301, and adds a self-grouting three-section floating hoop 308, thus solving the problem of sealed "dead cavities" in traditional pipe column structures.

[0046] like Figure 3 As shown, in this embodiment, the tailpipe assembly 300 includes a guide shoe 302, a screen pipe string 303, a blind plate short section 306, a cement umbrella 309, a swirl short section 307, a three-section float hoop 308, and a suspension body 304 arranged coaxially from bottom to top. The second seat ring 301 is coaxially arranged on the outer wall of the suspension body 304.

[0047] During cementing operations, cement slurry inside the tailpipe assembly 300 is returned from the annulus between the tailpipe assembly 300 and the wellbore through the swirling short section 307.

[0048] In one embodiment, the swirl sub 307 includes a swirl sub body 3071. The swirl sub body 3071 is a tubular structure with several rows of swirl holes 3072 on its sidewall. The central axis of the swirl holes 3072 can be set not along the radial direction of the swirl sub body 3071, but at a certain inclination angle. During cementing operations, cement slurry returns from the annulus through the swirl holes 3072. Because the swirl holes 3072 are inclined at a certain angle, the mud flows out along a certain inclination angle after exiting, resulting in more uniform mud injection. This embodiment replaces the existing staged cement injector with the swirl sub 307, eliminating the need for multi-stage operations of the staged cement injector and operations such as opening and closing holes, thus reducing complexity and risk. The swirl sub 307 serves as a channel connecting the inside and outside of the tubing string, allowing fluid to flow freely and eliminating "dead space." This prevents the generation of liquid column turbulence pressure during the lowering process, preventing accidents caused by unexpected pressure fluctuations.

[0049] The 306 blind flange short section is used to seal the lower tubing column and form an isolation zone.

[0050] The three-section floating collar 5 connects the running tubing and the annulus during the running process, changing the closed "dead cavity" structure in the traditional tubing structure. It also eliminates the need for grouting at the wellhead during the running process, saving construction time, and reduces the impact pressure of the casing on the bottom of the well, thus avoiding construction risks.

[0051] The bottom of the guide shoe 302 is a rotatable eccentric guide head, which can guide the tubing column downwards and reduce the resistance during insertion.

[0052] The 303 screen string is a core component of well completion, used to filter formation fluids and prevent sand particles from entering the tubing.

[0053] The cement umbrella 309 can seal the annulus between the tailpipe assembly 300 and the well wall, and play a role in supporting the upper cement to prevent displacement, thus preventing the upper cement in the annulus from being replaced by the drilling fluid in the screen section and contaminating the bottom layer.

[0054] In one embodiment, a tailpipe plug 311 is provided above the three-part float 308.

[0055] According to the present invention, the construction process of the geothermal well string 1000 equipped with the swirl section 307 is as follows.

[0056] The surface casing 100 was lowered into the well.

[0057] Then, the technical sleeve 200 is lowered in, so that the first mounting ring 201 on the technical sleeve 200 axially overlaps the first bearing short section 101, realizing the fixed mounting of the technical sleeve 200. After the technical sleeve 200 is delivered into place by the first feeding tool 210 (the first mounting ring 201 axially abuts against the first bearing short section 101), the first feeding tool 210 is pressed down to increase the friction between the first mounting ring 201 and the first bearing short section 101. By rotating the first feeding tool 210 in the forward direction, the first feeding tool 210 is rotated relative to the connecting body 203, so that the first feeding tool 210 is released from the connecting body 203. Then, the first feeding tool 210 is pulled out. Afterwards, the cementing drill pipe and insert head are lowered. The insert head can work with the insert-type float collar of the technical casing 200 to complete the internal cementing operation. The cement slurry enters directly into the annulus between the technical casing 200 and the wellbore through the cementing drill pipe, insert head, and insert-type float collar, avoiding the generation of slurry mixing in the technical casing 200. The use of volume replacement eliminates the need to put in cementing plugs, reducing the time for drilling and removing cement plugs and accessory cores, improving construction efficiency, and improving cementing quality.

[0058] Then, a second insertion tool 310 is coaxially connected above the tailpipe assembly 300. The tailpipe assembly 300 is then inserted into the well via the second insertion tool 310, causing the second mounting ring 301 of the tailpipe assembly 300 to axially overlap the second bearing short section 202, achieving fixed-point mounting of the casing 200. Next, the second insertion tool 310 is pressed down, increasing the friction between the second mounting ring 301 and the second bearing short section 202. By rotating the second insertion tool 310 forward, it rotates relative to the tailpipe assembly 300, thus releasing the second insertion tool 310 from the tailpipe assembly 300. Then, cementing is performed by connecting the cementing device to the wellhead, releasing the drill pipe plug 312. The drill pipe plug 312 replaces the cement slurry, and the cement enters the casing annulus through the vortex short section 307 to seal the upper part of the screen pipe.

[0059] Compared to conventional screen pipe top cementing process, this embodiment uses a simple swirl section 307 instead of a complex differential pressure staged cementing device to establish a cement ring circulation channel above the screen pipe string 303. Multiple sets of low-cost cement umbrellas 309 replace high-cost external packers to prevent the cement in the upper annulus from displacing and contaminating the bottom layer with the drilling fluid in the screen pipe section. This saves a lot of costs in terms of tools. In terms of operation, it eliminates the steps of establishing circulation by opening the internal pressure hole and opening the pressure expansion packer, reducing the difficulty of operation.

[0060] 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.

[0061] 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 connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A geothermal well tubing string, characterized in that, include: Surface sleeve (100), on which a first load-bearing short section (101) is provided; A technical sleeve (200) is provided on the outer wall of which a first seat ring (201) is provided for fitting the first bearing short section (101), and a second bearing short section (202) is provided on the technical sleeve (200), the second bearing short section (202) being located below the first seat ring (201); Tailpipe assembly (300) has a second seat ring (301) on its outer wall for adaptation to the second support section (202).

2. The geothermal well tubing according to claim 1, characterized in that, The first seat ring (201) and the second seat ring (301) are constructed in the shape of a ring. A limiting step is provided on the inner wall of the first bearing section (101) to axially abut against the first seat ring (201); a limiting step is provided on the inner wall of the second bearing section (202) to axially abut against the second seat ring (301).

3. The geothermal well tubing string according to claim 2, characterized in that, The technical sleeve (200) includes a connector (203), the second bearing section (202) is coaxially disposed below the connector (203), and the first seat ring (201) is coaxially disposed on the outer wall of the connector (203).

4. The geothermal well tubing string according to claim 2, characterized in that, The tailpipe assembly (300) includes a guide shoe (302), a screen tube string (303), a suspension body (304), and a seat seal assembly (305) arranged coaxially from bottom to top. The second seat ring (301) is coaxially arranged on the outer wall of the suspension body (304). The seat seal assembly (305) is configured to seal the annular space between the tailpipe assembly (300) and the technical sleeve (200).

5. The geothermal well tubing string according to claim 4, characterized in that, The setting assembly (305) includes: A rubber sleeve (3051) is coaxially mounted on the outer wall of the suspension body (304); A movable cylinder (3052) is coaxially mounted on the outer wall of the suspension body (304), and the movable cylinder (3052) is located above the rubber cylinder (3051); An activation component (3050) is configured to move the movable cylinder (3052) downward relative to the suspension body (304), thereby axially compressing the rubber cylinder (3051) and causing the rubber cylinder (3051) to expand radially.

6. The geothermal well tubing according to claim 5, characterized in that, The activation component (3050) includes a setting section (3053) coaxially disposed within the movable cylinder (3052), and a setting block (3054) is provided on the outer wall of the setting section (3053). The setting block (3054) is elastic and can open outward in a radial direction.

7. The geothermal well tubing string according to claim 6, characterized in that, In the initial state, the setting short section (3053) is sleeved inside the moving cylinder (3052), and the setting stop block (3054) is in a retracted state; Lifting the setting section allows the setting section (3053) to move out from the upper end of the moving cylinder (3052), and the setting block (3054) opens radially. Then, pressing down the setting section (3053) causes the setting block (3054) to push the moving cylinder (3052) axially downward, thereby axially compressing the rubber cylinder (3051) to complete the setting.

8. The geothermal well tubing string according to claim 2, characterized in that, The tailpipe assembly (300) includes a guide shoe (302), a screen pipe string (303), a cement umbrella (309), a swirl section (307), a three-section float hoop (308), and a suspension body (304) arranged coaxially from bottom to top, and the second seat ring (301) is coaxially arranged on the outer wall of the suspension body (304).

9. The geothermal well tubing according to claim 8, characterized in that, The swirl section (307) includes a swirl section body (3071), and a swirl hole (3072) is provided on the side wall of the swirl section body (3071). The central axis of the swirl hole (3072) is inclined to the radial direction of the swirl section body (3071).

10. The geothermal well string according to claim 8 or 9, characterized in that, A blind flange section (306) is provided below the swirl section (6), the blind flange section (306) being configured to block the tubing.

11. A geothermal well construction process, characterized in that, include: The surface casing (100) with the first load-bearing short section (101) is lowered into the well; The technical casing (200) equipped with a first mounting ring (201) and a second bearing sub (202) is lowered into the well, so that the first mounting ring (201) is mounted on the first bearing sub (101), and the technical casing (200) is cemented using the insertion method. The tailpipe assembly (300) equipped with the second mounting ring (301) is lowered into the well, so that the second mounting ring (301) is mounted on the second bearing short section (202), and the annulus between the tailpipe assembly (300) and the technical casing (200) is sealed by the setting seal assembly (305).

12. A geothermal well construction process, characterized in that, include: The surface casing (100) with the first load-bearing short section (101) is lowered into the well; The technical casing (200) equipped with a first mounting ring (201) and a second bearing sub (202) is lowered into the well, so that the first mounting ring (201) is mounted on the first bearing sub (101), and the technical casing (200) is cemented using the insertion method. The tailpipe assembly (300) equipped with the second mounting ring (301) is lowered into the well, so that the second mounting ring (301) is mounted on the second bearing short section (202), and the tailpipe assembly (300) is cemented by the swirl short section (307).

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