Carbon dioxide layer-by-layer return layered buried tubing and its layer-by-layer gas injection and sealing method

Abstract

This invention discloses a layered carbon dioxide backfilling and storage string and its layered gas injection and sealing method. The setting and release string, from bottom to top, includes a tailpipe, a one-way gas injection valve, a gas-tight packer, an annular ash injection valve, a release connector, and an upper setting tubing. The gas-tight packer and the annular ash injection valve are located between the lower and upper gas injection layers. After the upper setting tubing is pulled out, an insert gas injection string is lowered. The insert gas injection string includes an upper ash injection tubing and an ash injection insert, which is connected to the lower part of the upper ash injection tubing via a variable-thread connector. After the insert gas injection string is pulled out of the wellhead, an insert gas injection string is lowered. The lower end of the gas injection insert is inserted into the central tube of the gas-tight packer to achieve sealed gas injection. The combination of annular ash injection valve and gas-tight packer is used to inject ash into the annulus above the gas-tight packer. By using a drop-out tubing string and an insertion-tube ash injection string, the next layer can be buried after a single layer of ash injection, thus achieving layer-by-layer burial.

Description

Technical Field

[0001] This invention relates to a downhole tubing string, and more particularly to a carbon dioxide layer-by-layer return and stratified storage tubing string. This invention also relates to a carbon dioxide layer-by-layer injection and sealing method, belonging to the field of carbon dioxide storage technology. Background Technology

[0002] Carbon dioxide storage is the most effective way to address peak carbon emissions and achieve carbon neutrality, reducing carbon dioxide emissions. Currently, in China, a combination of oil displacement and storage is commonly used to improve oil recovery while simultaneously storing carbon dioxide. This method primarily focuses on oil displacement, with relatively small carbon dioxide storage volumes. To accelerate carbon storage, carbon dioxide needs to be stored in brine layers. However, there are currently no mature carbon dioxide layer-by-layer storage tubing systems in China. The existing injection tubing is affected by carbon dioxide sealing, temperature changes, high pressure, and corrosion, resulting in generally short lifespans. Meanwhile, storage requires high injection pressure and long cycles, placing high demands on the tubing. Conventional injection tubing cannot meet the needs of storage tubing and cannot achieve layer-by-layer storage. Therefore, a tubing system suitable for carbon dioxide storage needs to be designed.

[0003] Chinese invention patent CN107178347B discloses a long-lasting CO2 injection tubing string and its operation method. The string includes an upper tubing string and a lower tubing string. The upper tubing string includes tubing fitted inside the casing. From top to bottom, the tubing string is arranged with a circulating well-washing sleeve, a hydraulic anchor, a hanging ring, and a sealing insert. The lower tubing string includes a sealing cylinder and a packer arranged sequentially on the tubing. A setting ball seat and a two-stage check valve are located at the bottom of the lower tubing string. The lower tubing string is fixed to the inner wall of the casing by the anchor of the packer. The circulating well-washing sleeve closes the string during water injection and opens it during backwashing. This technical solution addresses the problem of low packer gas seal reliability and a high failure rate by using a permanent packer to improve sealing reliability and adding a reconnection insert above the Y443 packer to eliminate the influence of tubing creep on the packer. However, it does not solve the problem of poor sealing effect after long-term use of the packer's rubber sleeve. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0006] The primary objective of this invention is to provide a layered carbon dioxide return and storage tubing string that can solve the problems of short downhole effectiveness, rapid failure, and inability to achieve long-term layered injection of existing gas injection tubing sealing tools.

[0007] To solve the above technical problems, the present invention provides a carbon dioxide layer-by-layer backfilling tubing string, including a setting and release tubing string extending to the bottom of the well. The setting and release tubing string includes, from bottom to top, a tailpipe, a one-way gas injection valve, a gas-tight packer, an annular ash injection valve, a release connector, and an upper setting tubing. The lower end of the tailpipe is provided with a plug. The gas-tight packer and the annular ash injection valve are located above the lower gas injection layer and below the upper gas injection layer.

[0008] Furthermore, the annular ash injection valve includes an upper ash injection connector, the lower end of which is externally threaded with a downwardly extending ash injection outer sleeve, and the lower end of which is internally threaded with a downwardly extending ash injection inner tube. A spring is provided in the annular space between the ash injection inner tube and the ash injection outer sleeve. The top of the spring abuts against the lower end face of the upper ash injection connector, and the bottom of the spring abuts against the top of the annular piston. The bottom of the annular piston abuts against the outer step of the ash injection inner tube. Multiple outer sleeve ash injection ports are evenly distributed on the lower circumference of the ash injection outer sleeve, and multiple inner tube ash injection ports are evenly distributed on the lower circumference of the ash injection inner tube corresponding to the annular piston.

[0009] Furthermore, the lower inner cavity of the ash-filling inner tube is provided with a protective ring to block the ash-filling port of the inner tube. The protective ring is fixed to the inner wall of the ash-filling inner tube by a shear pin. The upper end of the protective ring is provided with a flared mouth. The upper and lower outer circumferences of the protective ring are respectively embedded with protective ring sealing rings to achieve a seal with the upper and lower inner walls of the ash-filling port of the inner tube.

[0010] Furthermore, the lower end of the ash-filling outer jacket is provided with a reduced diameter section, and the lower end of the ash-filling inner tube is inserted into the reduced diameter section at the lower end of the ash-filling outer jacket.

[0011] Furthermore, the upper and lower inner walls of the annular piston are respectively fitted with piston inner sealing rings to achieve a seal with the upper and lower outer walls of the inner tube ash injection port, and the upper and lower outer walls of the annular piston are respectively fitted with piston outer sealing rings to achieve a seal with the inner wall of the ash injection jacket.

[0012] Furthermore, the lower inner wall of the ash-filling inner tube is provided with a reduced-diameter bottom inner step, and the distance between the bottom inner step and the ash-filling port of the inner tube is greater than the height of the sheath ring.

[0013] Furthermore, when the shear pin is cut, the sheath ring slides down to its bottom and abuts against the bottom inner step of the ash-filling inner tube.

[0014] Furthermore, after the release connector is released, the upper setting oil pipe is removed, and the insert ash injection pipe string is lowered. The insert ash injection pipe string includes an upper ash injection oil pipe and an ash injection insert pipe. The ash injection insert pipe is connected to the lower part of the upper ash injection oil pipe through a variable thread connector.

[0015] Furthermore, the lower end of the ash-filling tube is provided with an outer cone, and a plurality of ash-filling ports are symmetrically arranged around the lower part of the outer cone and communicate with the central hole of the tube. Two tube sealing rings are respectively embedded on the upper and lower sides of the ash-filling ports.

[0016] Furthermore, the outer cone of the lower end of the ash injection tube is inserted into the upper flared end of the sheath ring of the annular ash injection valve and they are matched.

[0017] Furthermore, after the sheath ring falls into place, the distance between the upper end of its flared end and the ash injection port of the inner tube is equal to the distance between the large end of the outer cone of the ash injection tube and the ash injection port of the tube.

[0018] Furthermore, after the ash injection tube is inserted into the protective ring of the annular ash injection valve, the ash injection port of the inner tube and the ash injection port of the insertion tube are connected in a one-to-one correspondence.

[0019] Furthermore, the outer circumference of the ash injection port of the insertion tube is provided with an annular groove for the insertion tube. After the ash injection insertion tube is inserted into the protective ring of the annular ash injection valve, the ash injection ports of each inner tube correspond to the annular groove of the insertion tube.

[0020] Furthermore, after the injection string is pulled out of the wellhead, an injection string is lowered into the gas injection string. The injection string includes an upper gas injection tubing and an injection pipe. The injection pipe is connected to the lower part of the upper gas injection tubing via a variable-thread connector.

[0021] Furthermore, the outer diameter of the gas injection tube is smaller than the inner diameter of the sheath ring of the annular ash injection valve.

[0022] Furthermore, the middle section of the gas injection tube passes through the sheath ring of the annular ash injection valve, and the lower end of the gas injection tube is inserted into and matched with the central tube of the gas-tight packer. The lower end of the gas injection tube is fitted with a sealing ring on its outer periphery to achieve sealed gas injection with the central tube of the gas-tight packer.

[0023] Another objective of this invention is to provide a layered carbon dioxide return and storage tubing string, which can solve the problems of short downhole effectiveness, rapid failure, and inability to achieve long-term layered injection of existing gas injection tubing sealing tools.

[0024] To solve the above technical problems, the carbon dioxide layer-by-layer gas injection sealing method of the present invention includes the following steps in sequence:

[0025] S1, Lower Setting and Release Tubing String: From bottom to top are plug, tail pipe, one-way gas injection valve, gas-tight packer, annular ash injection valve, release connector and upper setting tubing. The annular ash injection valve and gas-tight packer are located between the upper gas injection layer and the lower gas injection layer. The gas-tight packer is pressurized and set.

[0026] S2. Release the connector and remove the upper end of the seated oil pipe;

[0027] S3, Lower insertion pipe annular ash injection pipe string: From top to bottom are upper ash injection oil pipe, variable coupling and ash injection insertion pipe. The lower end of the ash injection insertion pipe is inserted into the annular ash injection valve to open the ash injection channel of the annular ash injection valve.

[0028] S4. Reverse circulation cleaning: Cleaning fluid is injected from the annulus of the oil casing. The cleaning fluid enters the central channel from the ash injection channel of the annulus ash injection valve and goes up to the wellhead to achieve reverse circulation and clean the ash injection channel.

[0029] S5. Reverse circulation grouting: Grout is injected from the annulus of the oil jacket. The grout reaches the rubber sleeve of the airtight seal and then enters the inner cavity of the grouting tube through the grouting channel of the annulus grouting valve. After the set grouting volume is reached, the grouting tube is lifted so that its lower end is disengaged from the annulus grouting valve, and the grouting channel of the annulus grouting valve is closed. The cement grout in the grouting tube falls and fills the outer periphery of the release joint.

[0030] S6. Positive circulation well washing: Inject cleaning fluid from the central channel. The cleaning fluid flows out from the lower end of the ash injection pipe and then returns to the wellhead to clean the oil casing annulus slurry above the release joint.

[0031] S7. Pulling out the pipe and waiting for it to set: Pull the mortar-injected pipe out of the wellhead and wait for the cement mortar to set until the annulus between the release joint and the gas-tight packer sleeve is sealed.

[0032] S8. Inserting the gas injection tube: Insert the gas injection tube string. From top to bottom, there is the upper gas injection oil pipe, the variable coupling and the gas injection tube. The lower end of the gas injection tube is inserted into the central tube of the gas-tight packer and a seal is achieved. Gas is injected into the lower gas injection layer.

[0033] S9. Sealing the gas injection zone: Grout is squeezed from the central channel and injected into the gas injection zone.

[0034] S10, Pulling out the tubing and waiting for it to solidify: Pull up the gas injection tubing string so that the lower end of the gas injection tubing is separated from the annular ash injection valve. Then, perform positive circulation well flushing, pull out the tubing, and wait for it to solidify to complete the sealing of the lower gas injection zone.

[0035] Furthermore, it also includes the following steps:

[0036] S11. Gas injection in the upper gas injection layer: Design the packer locking point position according to the location of the upper gas injection layer, take the upper gas injection layer adjacent to the sealing layer as the new lower gas injection layer, return to step S1, realize the gas injection of the upper layer, and repeat this cycle to complete the gas injection and sealing of all gas injection layers.

[0037] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. By using the combination of annular ash injection valve and packer, ash is injected into the annulus above the packer, protecting the packer rubber sleeve, extending the service life of the rubber sleeve, thereby improving the reliability of the packer, and further improving the reliability of carbon dioxide buried tubing.

[0038] 2. By using a drop-out tubing string + a tube-insertion gas injection tubing string, the next layer can be buried after a single layer of gas injection, achieving layer-by-layer burial.

[0039] 3. It can completely solve the problem that the existing injection tubing cannot achieve layer-by-layer backfilling. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit the present invention. Wherein:

[0041] Figure 1 This is a schematic diagram of the annular ash injection valve in this invention;

[0042] Figure 2 This is a schematic diagram of the ash-filling insertion tube in this invention;

[0043] Figure 3 This is a schematic diagram showing the process after the set-off tubing string is inserted into the well and the gas injection zone is reached.

[0044] Figure 4 This is a diagram showing the state of the set-off tubing after the set-off tubing has been released.

[0045] Figure 5 This is a schematic diagram after the insertion of the injection tube column;

[0046] Figure 6 for Figure 5 A schematic diagram of the structure after the central ash injection pipe is combined with the annular ash injection valve;

[0047] Figure 7 This is a diagram showing the state of reverse circulation ash injection before gas injection in the lower gas injection layer section;

[0048] Figure 8A schematic diagram of the process of injecting gas into the lower gas injection zone by inserting the gas injection string;

[0049] Figure 9 This is a diagram showing the state of the gas-injected layer during the ash-filling and sealing process.

[0050] Figure 10 This is a diagram showing the state of the gas injection layer during the condensation process after the pipe is started.

[0051] Figure 11 A schematic diagram of the section from the newly set and unloaded tubing string to the upper gas injection zone;

[0052] In the diagram: 1. Upper setting oil pipe; 2. Release connector;

[0053] Annular ash injection valve 3: ash injection upper connector 3a; ash injection outer sleeve 3b; outer sleeve ash injection port 3b1; ash injection inner tube 3c; inner tube ash injection port 3c1, bottom inner step 3c2; spring 3d; annular piston 3e; protective ring 3f; shear pin 3g;

[0054] 4. Airtight seal; 5. One-way air injection valve; 6. Tail pipe; 6a. Plug; 7. Upper ash injection pipe;

[0055] 8; 8a; 8b; 8c; 8d; 8d; 8a; 8b; 8c; 8d; 8d;

[0056] Upper gas injection oil pipe 9; gas injection insertion pipe 10. Detailed Implementation

[0057] In the following description of the present invention, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific orientation.

[0058] To make the technical means, creative features, objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific illustrations. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0060] like Figure 1As shown, the annular ash injection valve 3 used in this invention includes an upper ash injection connector 3a, an outer ash injection sleeve 3b, an inner ash injection tube 3c, a spring 3d, an annular piston 3e, a protective ring 3f, and a shear pin 3g. The upper end of the inner ash injection tube 3c is screwed to the lower end of the upper ash injection connector 3a via an internal thread. The lower circumference of the inner ash injection tube 3c is provided with an inner ash injection port 3c1, and the lower end of the inner ash injection tube 3c is provided with a reduced-diameter bottom inner step 3c2.

[0061] Spring 3d and annular piston 3e are fitted around the outer periphery of the inner grouting tube 3c and located within the inner cavity of the outer grouting tube 3b. The top of spring 3d abuts against the lower end face of the upper grouting connector 3a, and the top of annular piston 3e abuts against the lower end of spring 3d. The lower end of annular piston 3e abuts against the lower outer step of the inner grouting tube 3c. Sheath ring 3f is fixed to the lower end of the inner cavity of the inner grouting tube 3c by shear pin 3g, sealing the inner tube grouting port 3c1. Sheath sealing rings are fitted at both the upper and lower ends of the inner tube grouting port 3c1 to prevent grout leakage. The lower end of the outer grouting tube 3b has an outer grouting port 3b1, located below the bottom of the annular piston 3e.

[0062] like Figure 2 As shown, the lower end of the ash injection tube 8 used in this invention is provided with an outer cone 8a. Multiple ash injection ports 8c are symmetrically arranged around the lower circumference of the ash injection tube 8, communicating with the central hole of the tube. Two sealing rings 8b are respectively embedded on the upper and lower sides of the ash injection ports 8c. The outer cone 8a of the ash injection tube 8 is inserted into the upper flared end of the sheath ring 3f of the annular ash injection valve 3. Pressure is applied to cut the shear pin 3g. The bottom of the sheath ring 3f falls on the bottom inner step 3c2 of the inner ash injection tube 3c. The ash injection ports 8c of the ash injection tube 8 correspond to the inner tube ash injection ports 3c1 of the annular ash injection valve 3, completing the ash injection tube column insertion.

[0063] The setting and release string of this invention comprises, from top to bottom, an upper setting oil pipe 1, a release connector 2, an annular ash injection valve 3, a gas-tight packer 4, a one-way gas injection valve 5, and a tail pipe 6. A plug 6a is provided at the lower end of the tail pipe 6. The annular ash injection valve 3 and the gas-tight packer 4 are located between the upper and lower gas injection layers. The main ash injection location is the annulus between the gas-tight packer 4 and the annular ash injection valve 3. By injecting ash into the annulus above the gas-tight packer 4, the rubber sleeve of the gas-tight packer 4 is protected, thereby extending the service life of the gas-tight packer 4.

[0064] The combination of annular ash injection valve 3 and gas-tight packer 4 is used to inject ash into the annulus above the gas-tight packer 4, so as to protect the gas-tight packer 4 and extend its service life. By using a drop-out tubing string and an insertion-tube ash injection string, the next layer can be buried after a single layer of ash injection, so as to realize the layer-by-layer burial.

[0065] The carbon dioxide layer-by-layer backfilling and burial column can realize layer-by-layer backfilling and burial. Its main operation procedures include setting and releasing the seal, inserting the tube and injecting ash into the annulus, and inserting the tube and injecting gas. After the first layer of gas injection and burial is completed, the ash is squeezed and sealed by the gas injection column and the backfilling operation is carried out to realize the continued gas injection in the upper layer.

[0066] The carbon dioxide layer-by-layer gas injection sealing method of the present invention includes the following steps in sequence:

[0067] S1, Lower seat seal drop tube column: such as Figure 3 As shown, the setting and release string is lowered into the design sealing point. The string structure from bottom to top consists of plug 6a, tail pipe 6, one-way gas injection valve 5, gas-tight packer 4, annular ash injection valve 3, release connector 2, and upper setting oil pipe 1. The annular ash injection valve 3 and gas-tight packer 4 are located between the upper and lower gas injection layers. The gas-tight packer 4 is pressurized and anchored to set the seal according to the design setting pressure.

[0068] S2, Upper tubing string lost: such as Figure 4 As shown, first, insert the matching gas injection valve ball to open the one-way gas injection valve 5, then continue to insert the matching release valve ball, pressurize to release the release connector 2, and pull out the upper set tubing 1 and above. The release valve ball follows the tubing out of the well. Alternatively, the gas injection valve ball and the release valve ball can be made of plastic balls with a certain degree of elasticity. After the operation is completed, pressurize to squeeze them out and let them fall into the tailpipe 6.

[0069] S3, Lower insertion annular ash injection pipe string (hereinafter referred to as ash injection pipe string): such as Figure 5 As shown, according to the design, the annular ash injection string (hereinafter referred to as the ash injection string) has the following structure from bottom to top: ash injection insert 8, variable coupling, and upper ash injection oil pipe 7. The outer cone 8a of the ash injection insert 8 is inserted into the upper flared end of the sheath ring 3f of the annular ash injection valve 3, and pressure is applied to cut the shear pin 3g. Figure 6 As shown, the bottom of the sheath ring 3f rests on the inner step 3c2 at the bottom of the ash injection inner tube 3c, the ash injection port 8c of the ash injection tube 8 corresponds to the ash injection port 3c1 of the inner tube of the annular ash injection valve 3, and the ash injection tube column is in place; the two ash injection sealing rings 8b at the upper and lower ends of the ash injection port 8c seal with the inner wall of the ash injection inner tube 3c, preventing ash leakage at the upper and lower ends of the ash injection port 8c and the ash injection port 3c1.

[0070] S4. Reverse circulation cleaning: Cleaning fluid is injected into the annulus. The cleaning fluid enters the inner cavity of the outer casing 3b through the outer casing ash injection port 3b1 of the annulus ash injection valve 3, pushing the annular piston 3e to overcome the resistance of the spring 3d and move upward, exposing the inner tube ash injection port 3c1. The fluid then enters the inner cavity of the ash injection tube 8 through the inner tube ash injection port 3c1 and the insertion tube ash injection port 8c, and then moves upward to the wellhead to achieve reverse circulation and clean the ash injection channel.

[0071] S5, Reverse circulation ash injection: (e.g.) Figure 7 As shown, mortar is injected into the annulus between the gas-tight packer 4 and the annulus mortar injection valve 3. The mortar reaches the top of the rubber sleeve of the gas-tight packer 4, and then enters the inner cavity of the outer mortar injection port 3b1 of the annulus mortar injection valve 3, pushing the annular piston 3e to move upward against the resistance of the spring 3d. The mortar then enters the inner cavity of the mortar injection tube 8 through the inner tube mortar injection port 3c1 and the insertion tube mortar injection port 8c.

[0072] After the set amount of cement grout is reached, the cement grout in the grouting tube 8 reaches the predetermined height, the grouting tube column is lifted, and the lower end of the grouting tube 8 is disengaged from the annular grouting valve 3. The annular piston 3e is reset under the tension of the spring 3d, closing the grouting port 3c1 of the inner tube. The cement grout in the grouting tube 8 falls and fills the outer periphery of the release joint 2.

[0073] S6. Positive circulation well washing: Inject cleaning fluid from the central channel. The cleaning fluid flows out from the lower end of the ash injection pipe 8 and then returns to the wellhead to clean the oil casing annulus slurry above the release connector 2.

[0074] S7. Pulling out the pipe and waiting for it to set: Pull the mortar injection pipe 8 out of the wellhead, and let the cement mortar enter the waiting area until the annular space between the release joint 2 and the rubber sleeve end of the gas seal packer 4 is sealed.

[0075] S8. Intubation and insufflation: (e.g.) Figure 8 As shown, the lower insertion tube gas injection string is inserted. The string structure from bottom to top consists of the gas injection tube 10, the variable thread connector, and the upper gas injection oil pipe 9. The middle section of the gas injection tube 10 passes through the sheath ring 3f of the annular ash injection valve 3. The lower end of the gas injection tube 10 is inserted into the central tube of the gas-tight packer 4 and they are matched. The lower end of the gas injection tube 10 is fitted with a sealing ring on its outer periphery to achieve a seal with the central tube of the gas-tight packer 4. Then, sealed gas injection is performed. Carbon dioxide flows out from the bypass port of the one-way gas injection valve 5 and is injected into the lower gas injection layer until the designed gas injection volume is reached.

[0076] S9. Blocking the gas injection zone: such as Figure 9 As shown, after the lower gas injection layer reaches the designed gas injection volume, it is sealed; mortar is squeezed from the central channel and injected into the lower gas injection layer until the set volume is reached.

[0077] S10, Initiating the process and waiting for condensation: (as follows) Figure 10 As shown, the gas injection string is pulled up so that the lower end of the gas injection tubing 10 is separated from the annular ash injection valve 3. Then, the well is flushed by positive circulation, the tubing is pulled out, and the solidification is allowed to complete the sealing of the lower gas injection layer.

[0078] S11, Gas injection in the upper gas injection layer: such as Figure 11As shown, the packer locking point position and tubing combination are designed according to the location of the interlayer and the upper gas injection layer. The upper gas injection layer adjacent to the sealing layer is taken as the new lower gas injection layer. Return to step S1 to realize the gas injection of the upper layer. Repeat this cycle to complete the gas injection and sealing of all gas injection layers.

[0079] The lower end of the tail tube of the upper-level setting and release tube column can be screwed with a plug or inserted into the release connector of the lower level.

[0080] The above description is merely a preferred embodiment of the present invention, showing and describing the basic principles, main features, and advantages of the present invention. It is not intended to limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. In addition to the above embodiments, the present invention may have other implementations without departing from the spirit and scope of the invention. Various changes and modifications to the present invention are possible, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents. Technical features not described in the present invention can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A layered buried carbon dioxide storage column with progressively upward carbon dioxide return, characterized in that, The set-and-release tubing string extends to the bottom of the well. The set-and-release tubing string includes, from bottom to top, a tailpipe (6), a one-way gas injection valve (5), a gas-tight packer (4), an annular ash injection valve (3), a release connector (2), and an upper set-and-release tubing (1). The lower end of the tailpipe (6) is provided with a plug (6a). The gas-tight packer (4) and the annular ash injection valve (3) are located above the lower gas injection layer and below the upper gas injection layer. The annular ash injection valve (3) includes an upper ash injection connector (3a), the lower end of which is externally threaded with an outer ash injection sleeve (3b), and the lower end of which is internally threaded with an inner ash injection tube (3c). A spring (3d) is provided in the annular space between the inner ash injection tube (3c) and the outer ash injection sleeve (3b). The top of the spring (3d) abuts against the lower end face of the upper ash injection connector (3a), and the bottom of the spring (3d) abuts against the top of the annular piston (3e). The bottom of the annular piston (3e) abuts against the outer step of the inner ash injection tube (3c). Multiple outer ash injection ports (3b1) are evenly distributed on the lower circumference of the outer ash injection sleeve (3b), and multiple inner ash injection ports (3c1) are evenly distributed on the lower circumference of the inner ash injection tube (3c) corresponding to the annular piston (3e). The lower inner cavity of the ash-filling inner tube (3c) is provided with a protective ring (3f) to block the ash-filling port (3c1) of the inner tube. The protective ring (3f) is fixed to the inner wall of the ash-filling inner tube (3c) by a shear pin (3g). The upper end of the protective ring (3f) is provided with a flared mouth. The upper and lower outer circumferences of the protective ring (3f) are respectively embedded with protective ring sealing rings to achieve a seal with the upper and lower inner walls of the ash-filling port (3c1) of the inner tube.

2. The carbon dioxide layer-by-layer buried storage column according to claim 1, characterized in that: The lower end of the ash injection jacket (3b) is provided with a reduced diameter section, and the lower end of the ash injection inner tube (3c) is inserted into the reduced diameter section at the lower end of the ash injection jacket (3b).

3. The carbon dioxide layer-by-layer buried storage column according to claim 1, characterized in that: The annular piston (3e) has inner piston sealing rings embedded in its upper and lower inner walls, which seal the upper and lower outer walls of the inner tube ash injection port (3c1). The annular piston (3e) has outer piston sealing rings embedded in its upper and lower outer walls, which seal the inner walls of the ash injection jacket (3b).

4. The carbon dioxide layer-by-layer buried storage column according to claim 2, characterized in that: The lower inner wall of the ash-filling inner tube (3c) is provided with a reduced-diameter bottom inner step (3c2), and the distance between the bottom inner step (3c2) and the ash-filling port (3c1) of the inner tube is greater than the height of the sheath ring (3f).

5. The carbon dioxide layer-by-layer buried storage column according to claim 4, characterized in that: When the shear pin (3g) is cut, the sheath ring (3f) slides down to its bottom and abuts against the bottom inner step (3c2) of the ash-filling inner tube (3c).

6. The carbon dioxide layer-by-layer buried storage column according to claim 5, characterized in that: After the release connector (2) is released, the upper end setting oil pipe (1) is pulled out and the insertion pipe ash injection column is lowered. The insertion pipe ash injection column includes an upper end ash injection oil pipe (7) and an ash injection insertion pipe (8). The ash injection insertion pipe (8) is connected to the lower end of the upper end ash injection oil pipe (7) through a variable thread connector.

7. The carbon dioxide layer-by-layer buried storage column according to claim 6, characterized in that: The lower end of the ash injection tube (8) is provided with an outer cone (8a). Near the lower part of the outer cone (8a), there are multiple ash injection ports (8c) that are symmetrically arranged around the lower part and communicate with the central hole of the tube. Two tube sealing rings (8b) are respectively installed on the upper and lower sides of the ash injection port (8c).

8. The carbon dioxide layer-by-layer buried storage column according to claim 7, characterized in that: The outer cone (8a) at the lower end of the ash injection tube (8) is inserted into the upper flared end of the sheath ring (3f) of the annular ash injection valve (3) and they are matched.

9. The carbon dioxide layer-by-layer buried storage column according to claim 8, characterized in that: After the sheath ring (3f) falls into place, the distance between the upper end of its flared mouth and the inner tube ash injection port (3c1) is equal to the distance between the large end of the outer cone (8a) of the ash injection tube (8) and the ash injection port (8c).

10. The carbon dioxide layer-by-layer upward return and stratified buried tubing according to claim 9, characterized in that: After the ash injection tube (8) is inserted into the sheath ring (3f) of the annular ash injection valve (3), the ash injection port (3c1) of the inner tube and the ash injection port (8c) of the insertion tube are connected in a one-to-one correspondence.

11. The carbon dioxide layer-by-layer buried storage column according to claim 9, characterized in that: The outer circumference of the ash injection port (8c) of the insertion tube is provided with an annular groove (8d). After the ash injection insertion tube (8) is inserted into the sheath ring (3f) of the annular ash injection valve (3), each inner tube ash injection port (3c1) corresponds to the annular groove (8d) of the insertion tube.

12. The carbon dioxide layer-by-layer buried storage column according to claim 6, characterized in that: After the ash injection tubing is pulled out of the wellhead, an air injection tubing is lowered in. The air injection tubing includes an upper air injection tubing (9) and an air injection tubing (10). The air injection tubing (10) is connected to the lower part of the upper air injection tubing (9) through a variable thread connector.

13. The carbon dioxide layer-by-layer buried storage column according to claim 12, characterized in that: The outer diameter of the gas injection tube (10) is smaller than the inner diameter of the sheath ring (3f) of the annular ash injection valve (3).

14. The carbon dioxide layer-by-layer buried storage column according to claim 13, characterized in that: The middle section of the gas injection tube (10) passes through the sheath ring (3f) of the annular ash injection valve (3). The lower end of the gas injection tube (10) is inserted into the central tube of the gas-tight packer (4) and they match each other. The lower end of the gas injection tube (10) is surrounded by a sealing ring that seals with the central tube of the gas-tight packer (4) to achieve gas injection.

15. A method for layer-by-layer carbon dioxide injection for sealing, characterized in that, The steps are as follows: S1, Lower Setting and Release Tubing String: From bottom to top are plug, tail pipe, one-way gas injection valve, gas-tight packer, annular ash injection valve, release connector and upper setting tubing. The annular ash injection valve and gas-tight packer are located between the upper gas injection layer and the lower gas injection layer. The gas-tight packer is pressurized and set. S2. Release the connector and remove the upper end of the seated oil pipe; S3, Lower insertion pipe annular ash injection pipe string: From top to bottom are upper ash injection oil pipe, variable coupling and ash injection insertion pipe. The lower end of the ash injection insertion pipe is inserted into the annular ash injection valve to open the ash injection channel of the annular ash injection valve. S4. Reverse circulation cleaning: Cleaning fluid is injected from the annulus of the oil casing. The cleaning fluid enters the central channel from the ash injection channel of the annulus ash injection valve and goes up to the wellhead to achieve reverse circulation and clean the ash injection channel. S5. Reverse circulation grouting: Grout is injected from the annulus of the oil jacket. The grout reaches the rubber sleeve of the airtight seal and then enters the inner cavity of the grouting tube through the grouting channel of the annulus grouting valve. After the set grouting volume is reached, the grouting tube is lifted so that its lower end is disengaged from the annulus grouting valve, and the grouting channel of the annulus grouting valve is closed. The cement grout in the grouting tube falls and fills the outer periphery of the release joint. S6. Positive circulation well washing: Inject cleaning fluid from the central channel. The cleaning fluid flows out from the lower end of the ash injection pipe and then returns to the wellhead to clean the oil casing annulus slurry above the release joint. S7. Pulling out the pipe and waiting for it to set: Pull the mortar injection pipe out of the wellhead, and wait for the cement mortar to set until the annulus between the release joint and the gas-tight packer sleeve is sealed. S8. Inserting the gas injection tube: Insert the gas injection tube string. From top to bottom, there is the upper gas injection oil pipe, the variable coupling and the gas injection tube. The lower end of the gas injection tube is inserted into the central tube of the gas-tight packer and a seal is achieved. Gas is injected into the lower gas injection layer. S9. Sealing the gas injection zone: Grout is squeezed from the central channel and injected into the gas injection zone. S10, Pulling out the tubing and waiting for it to solidify: Pull up the gas injection tubing string so that the lower end of the gas injection tubing is separated from the annular ash injection valve. Then, perform positive circulation well flushing, pull out the tubing, and wait for it to solidify to complete the sealing of the lower gas injection zone.

16. The carbon dioxide layer-by-layer gas injection sealing method according to claim 15, characterized in that... It also includes the following steps: S11. Gas injection in the upper gas injection layer: Design the packer locking point position according to the location of the upper gas injection layer, take the upper gas injection layer adjacent to the sealing layer as the new lower gas injection layer, return to step S1, realize the gas injection of the upper layer, and repeat this cycle to complete the gas injection and sealing of all gas injection layers.

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