Layer-by-layer upward-returning layered burying pipe column for carbon dioxide and layer-by-layer gas injection plugging method thereof

Abstract

The invention discloses a carbon dioxide layer-by-layer upward-returning layered burying pipe column and a layer-by-layer gas injection blocking method thereof. A setting releasing pipe column sequentially comprises a tail pipe, a one-way gas injection valve, a gas seal packer, an annular ash injection valve, a releasing connector and an upper end setting oil pipe from bottom to top. The air seal packer and the annular ash injection valve are located between the lower gas injection layer section and the upper gas injection layer section. And after the upper end setting oil pipe is pulled out, an insertion pipe cement injection pipe column is put in, the insertion pipe cement injection pipe column comprises an upper end cement injection oil pipe and a cement injection insertion pipe, and the cement injection insertion pipe is connected to the lower portion of the upper end cement injection oil pipe through an adapter connector. And after the intubation cement injection pipe column is pulled out of the wellhead, the intubation gas injection pipe column is put down, and the lower end of the gas injection intubation pipe is inserted into the central pipe of the gas seal packer to realize sealed gas injection. By means of the combination mode of the annular ash injection valve and the air seal packer, ash injection is carried out on an annular space on the upper portion of the air seal packer, the upper layer can be buried after single-layer air injection is carried out through the releasing tubular column and the insertion tube air injection tubular column, and layer-by-layer upward returning and layered burying is achieved.

Description

Technical Field

[0001] The present invention relates to a downhole tubular string, in particular to a carbon dioxide layer-by-layer up-flowing and layer-by-layer storage tubular string. The present invention also relates to a carbon dioxide layer-by-layer gas injection and plugging method, belonging to the technical field of carbon dioxide storage. Background Art

[0002] Carbon dioxide storage is the most effective way to cope with "carbon peak" and "carbon neutrality" and reduce carbon dioxide emissions. At present, China usually adopts a combination of oil recovery and storage to improve crude oil recovery while also achieving carbon dioxide storage. This storage method is mainly oil recovery, and the carbon dioxide storage volume is relatively small. In order to speed up the progress of carbon storage, carbon dioxide needs to be stored in saline layers. However, there is currently no mature carbon dioxide layer-by-layer storage string in China. The gas injection string used is affected by carbon dioxide sealing, temperature changes, high pressure, corrosion, etc., and the effective period of the string is generally short. The injection pressure of storage is high, the cycle is long, and the requirements for the string are high. Conventional gas injection strings cannot meet the needs of storage strings, and cannot achieve layer-by-layer storage. Therefore, it is necessary to design a string solution suitable for carbon dioxide storage.

[0003] Chinese invention patent publication number CN107178347B discloses a long-lasting CO2 injection string and operation method. The string comprises an upper string and a lower string. The upper string comprises a tubing sleeved within a casing, which is equipped with a circulating flushing sleeve, a hydraulic anchor, a looper, and a sealing cannula, in descending order. The lower string comprises a sealing sleeve and a packer, which are sequentially mounted on the tubing. A seating ball seat and a two-stage check valve are located at the bottom of the lower string. The lower string is secured to the inner wall of the casing via the packer's anchor shoe. The circulating flushing sleeve closes the lower string during water injection and opens it during backwashing. This technical solution addresses the low reliability and high failure rate of the packer's gas seal. It employs a permanent packer to make the seal more reliable. A tie-back cannula is added above the Y443 packer to eliminate the effects of string creep on the packer. However, it does not address the poor sealing effect of the packer's rubber sleeve after long-term use. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

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

[0006] The primary purpose of the present invention is to provide a layered buried carbon dioxide string for layer-by-layer upward return, which can solve the problems of existing gas injection string sealing tools with short downhole validity period, rapid failure and inability to achieve long-term layered injection.

[0007] In order to solve the above technical problems, the carbon dioxide layer-by-layer upward storage string of the present invention includes a set-and-release string extending to the bottom of the well. The set-and-release string includes, from bottom to top, a tail pipe, a one-way gas injection valve, an airtight seal packer, an annulus ash injection valve, a release joint and an upper end set-and-release oil pipe. The lower end of the tail pipe is provided with a wire plug. The airtight seal packer and the annulus ash injection valve are located above the lower gas injection layer section and below the upper gas injection layer section.

[0008] Furthermore, the annular space ash injection valve includes an upper ash injection joint, the lower end external thread of the upper ash injection joint is screwed with a ash injection sleeve extending downward, the lower end internal thread of the upper ash injection joint is screwed with a ash injection inner tube extending downward, a spring is provided in the annular space between the ash injection inner tube and the ash injection sleeve, the top of the spring abuts against the lower end face of the upper ash injection joint, 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, a plurality of outer sleeve ash injection ports are evenly distributed on the lower circumference of the ash injection sleeve, and a plurality of inner tube ash injection ports are evenly provided on the lower part of the ash injection inner tube and the circumference corresponding to the annular piston.

[0009] Furthermore, the lower inner cavity of the ash injection inner tube is provided with a protective ring that covers the ash injection port of the inner tube. The protective ring is fixed to the inner wall of the ash injection inner tube by shear nails. The upper end of the protective ring is provided with a bell mouth. The upper and lower outer peripheries of the protective ring are respectively embedded with protective ring sealing rings to achieve sealing with the upper and lower inner walls of the inner tube ash injection port.

[0010] Furthermore, the lower end of the putty injection outer sleeve is provided with a diameter-reducing section, and the lower end of the putty injection inner tube is inserted into the diameter-reducing section at the lower end of the putty injection outer sleeve.

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

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

[0013] Furthermore, when the shear nails are cut, the sheath ring slides down to its bottom and rests against the inner step at the bottom of the cement injection inner pipe.

[0014] Furthermore, after the release joint is released, the upper end sealing oil pipe is pulled out and the intubation cement injection pipe string is lowered. The intubation cement injection pipe string includes an upper end cement injection oil pipe and an cement injection intubation pipe. The cement injection intubation pipe is connected to the bottom of the upper end cement injection oil pipe through a variable buckle joint.

[0015] Furthermore, the lower end of the mortar injection cannula is provided with a cannula outer cone, and a plurality of cannula mortar injection ports are symmetrically provided near the lower circumference of the cannula outer cone and communicated with the cannula center hole. Two cannula sealing rings are respectively embedded on the upper and lower sides of the cannula mortar injection ports.

[0016] Furthermore, the outer cone of the lower end of the ash injection pipe is inserted into the bell mouth at the upper end of the sheath ring of the annular ash injection valve and matches each other.

[0017] Furthermore, after the sheath ring falls into place, the distance between the upper end of its bell mouth and the mortar injection opening of the inner pipe is equal to the distance between the outer cone end of the mortar injection pipe and the mortar injection opening of the pipe.

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

[0019] Furthermore, the circumferential outer wall where the insert pipe ash injection port is located is provided with an insert pipe annular groove. After the ash injection insert pipe is inserted into the sheath ring of the annular space ash injection valve, each inner pipe ash injection port corresponds to the insert pipe annular groove.

[0020] Furthermore, after the intubating cement injection string is pulled out of the wellhead, an intubating gas injection string is lowered. The intubating gas injection string includes an upper gas injection oil pipe and a gas injection intubation pipe, and the gas injection intubation pipe is connected to the bottom of the upper gas injection oil pipe through a variable buckle joint.

[0021] Furthermore, the outer diameter of the gas injection cannula 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 cannula passes through the sheath ring of the annulus ash injection valve, the lower end of the gas injection cannula is inserted into the central tube of the airtight seal and matches each other, and a sealing ring is embedded in the outer periphery of the lower end of the gas injection cannula to realize sealed gas injection with the central tube of the airtight seal.

[0023] Another object of the present invention is to provide a layered buried carbon dioxide string for layer-by-layer upward return, which can solve the problem that existing gas injection string sealing tools have a short downhole validity period, fail quickly, and cannot achieve long-term layered injection.

[0024] To solve the above technical problems, the carbon dioxide layer-by-layer gas injection and plugging method of the present invention comprises the following steps in sequence: S1. Lower setting and releasing string: from bottom to top, it includes the plug, tail pipe, one-way gas injection valve, gas-tight packer, annulus ash injection valve, releasing joint and upper end setting tubing. The annulus ash injection valve and gas-tight packer are located between the upper and lower gas injection sections. The gas-tight packer is pressurized and set. S2, release the joint and remove the upper end sealing oil pipe; S3. Lower annulus ash injection string: from top to bottom, it includes the upper end ash injection oil pipe, variable buckle joint and ash injection cannula. The lower end of the ash injection cannula is inserted into the annulus ash injection valve to open the ash injection channel of the annulus ash injection valve. S4, reverse circulation cleaning: Inject cleaning fluid from the casing annulus, and the cleaning fluid enters the central channel from the ash injection channel of the annulus ash injection valve and flows upward to the wellhead, realizing reverse circulation and cleaning the ash injection channel; S5. Reverse circulation cement injection: Cement slurry is injected from the annulus of the casing. The slurry reaches the top of the rubber sleeve of the airtight packer and then enters the inner cavity of the cement injection cannula through the cement injection channel of the annulus cement injection valve. When the set cement injection volume is reached, the cement injection cannula is lifted up so that its lower end is separated from the annulus cement injection valve, and the cement injection channel of the annulus cement injection valve is closed. The cement slurry in the cement injection cannula 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 port of the mortar injection cannula and then returns to the wellhead to clean the mortar in the casing annulus above the release joint. S7. Pull out the pipe and wait for setting: Pull the cement injection pipe out of the wellhead and wait for the cement slurry to set until the casing annulus between the release joint and the airtight packer rubber sleeve is sealed; S8, Intubation gas injection: Insert the intubation gas injection string, which includes the upper gas injection oil pipe, the variable buckle joint and the gas injection intubation pipe from top to bottom. The lower end of the gas injection intubation pipe is inserted into the central pipe of the gas-tight packer to achieve a seal, and then inject gas into the gas injection layer section; S9. Seal the lower gas injection layer: squeeze mortar from the central hole and squeeze the mortar into the lower gas injection layer; S10, lifting the pipe and waiting for solidification: lift the gas injection pipe string to separate the lower end of the gas injection pipe from the annulus ash injection valve, then perform positive circulation to wash the well, lift the pipe and wait for solidification to complete the plugging of the lower gas injection layer.

[0025] Furthermore, the following steps are included: S11. Gas injection in the upper gas injection layer: Design the packer card point position according to the position of the upper gas injection layer, take the upper gas injection layer adjacent to the plugging layer as the new lower gas injection layer, return to step S1, implement gas injection in the upper layer, and repeat this cycle to complete gas injection and plugging of all gas injection layers layer by layer.

[0026] Compared with the existing technology, the present invention has the following beneficial effects: 1. By combining an annulus ash injection valve with a packer, ash injection is implemented in the annulus above the packer, protecting the packer rubber sleeve and extending the service life of the rubber sleeve, thereby improving the reliability of the packer and further improving the reliability of the CO2 storage string; 2. Using the drop-handle string + intubation gas injection string, the upper layer can be buried after the single layer gas injection, realizing layer-by-layer burial; 3. It can completely solve the problem that the existing injection string cannot realize layer-by-layer backfilling and storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. 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 inventive work. The drawings are provided for reference and explanation only and are not intended to limit the present invention. Among them: Figure 1 This is a schematic diagram of the structure of the annular ash injection valve in the present invention; Figure 2 This is a schematic structural diagram of the ash injection cannula in the present invention; Figure 3 This is a schematic diagram of the setting and releasing string after it is run into the gas injection zone; Figure 4 This is the state diagram after the setting and releasing string is released; Figure 5 This is a schematic diagram of the ash injection column after it is lowered into the cannula; Figure 6 for Figure 5 Schematic diagram of the structure after the center ash injection cannula is combined with the annular ash injection valve; Figure 7 This is the state diagram of reverse circulation ash injection before gas injection in the lower gas injection layer; Figure 8 This is a schematic diagram of the lower gas injection layer section being injected with gas by inserting a cannulated gas injection string; Figure 9 This is the state diagram of the lower gas injection layer when ash injection and plugging; Figure 10 This is the state diagram of the gas injection layer section when the pipe is started and waiting for solidification; Figure 11 This is a schematic diagram of the newly set and released string running into the well to the upper gas injection zone; In the figure: upper end sealing oil pipe 1; release joint 2; Annulus injection valve 3: injection upper joint 3a; injection jacket 3b; jacket injection port 3b1; injection inner tube 3c; inner tube injection port 3c1, bottom inner step 3c2; spring 3d; annular piston 3e; sheath ring 3f; shear pins 3g; Airtight seal packer 4; one-way air injection valve 5; tail pipe 6; screw plug 6a; upper end ash injection oil pipe 7; Injection cannula 8; cannula outer cone 8a; cannula sealing ring 8b; cannula injection port 8c; cannula annular groove 8d; Upper end gas injection oil pipe 9; gas injection cannula 10. DETAILED DESCRIPTION

[0028] In the following description of the present invention, the terms "up", "down", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They 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 direction.

[0029] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0031] like Figure 1 As shown, the annulus injection valve 3 used in the present invention comprises an upper injection joint 3a, an outer injection sleeve 3b, an inner injection tube 3c, a spring 3d, an annular piston 3e, a sheath ring 3f, and shear pins 3g. The upper end of the inner injection tube 3c is threadedly connected to the internal thread of the lower end of the upper injection joint 3a. The lower circumference of the inner injection tube 3c is provided with an inner tube injection port 3c1, and the lower end of the inner injection tube 3c is provided with a reduced diameter bottom inner step 3c2.

[0032] A spring 3d and annular piston 3e are mounted around the outer periphery of the mortar injection inner tube 3c and within the inner cavity of the mortar injection outer sleeve 3b. The top of the spring 3d rests against the lower end of the mortar injection upper connector 3a, while the top of the annular piston 3e rests against the lower end of the spring 3d. The lower end of the annular piston 3e rests against the lower outer step of the mortar injection inner tube 3c. A sheath ring 3f is secured to the lower end of the mortar injection inner tube 3c via shear pins 3g, sealing the inner tube mortar injection port 3c1. Sheath seals are installed at the upper and lower ends of the inner tube mortar injection port 3c1 to prevent mortar leakage. The lower end of the mortar injection outer sleeve 3b is provided with a sheath mortar injection port 3b1, located below the bottom of the annular piston 3e.

[0033] like Figure 2 As shown, the lower end of the cement injection cannula 8 used in the present invention is provided with a cannula outer cone 8a. Multiple cannula injection ports 8c are symmetrically arranged around the lower circumference of the cannula 8, communicating with the cannula's central hole. Two cannula sealing rings 8b are respectively embedded on the upper and lower sides of the cannula injection ports 8c. The cannula outer cone 8a of the cement injection cannula 8 is inserted into the upper bell mouth of the sheath ring 3f of the annulus cement injection valve 3. Pressure is applied to shear the shear pins 3g, causing the bottom of the sheath ring 3f to rest on the inner step 3c2 at the bottom of the cement injection inner tube 3c. The cannula injection ports 8c of the cement injection cannula 8 correspond to the inner tube injection ports 3c1 of the annulus cement injection valve 3, completing the cannula cement injection string.

[0034] The set-and-release string in the present invention comprises, from top to bottom, an upper setting tubing 1, a release joint 2, an annulus ash injection valve 3, a hermetic packer 4, a one-way gas injection valve 5, and a tail pipe 6. The lower end of the tail pipe 6 is equipped with a threaded plug 6a. The annulus ash injection valve 3 and the hermetic packer 4 are located between the upper and lower gas injection zones. The primary location for ash injection is the oil-casing annulus between the hermetic packer 4 and the annulus ash injection valve 3. By injecting ash into the annulus above the hermetic packer 4, the rubber sleeve of the hermetic packer 4 is protected, thereby extending its service life.

[0035] The annulus ash injection valve 3 and the airtight packer 4 are combined to implement ash injection into the annulus above the airtight packer 4, so as to protect the airtight packer 4 and extend its service life. By using the hand-free string + the intubation gas injection string, the upper layer can be buried after the single layer of gas injection, realizing layer-by-layer burial.

[0036] The carbon dioxide layer-by-layer upward return and layer-by-layer storage string can realize the layer-by-layer upward return and gas storage. Its main operation procedures include setting and releasing the seal, inserting the tube to inject ash into the annulus, and inserting the tube to inject gas. When the gas injection and storage of one layer is completed, the inserting tube gas injection string is used to squeeze the ash and seal the layer, and then the upward return operation is carried out to realize the continued gas injection in the upper layer.

[0037] The carbon dioxide layer-by-layer gas injection and plugging method of the present invention comprises the following steps in sequence: S1, lower the sealing and releasing pipe string: Figure 3 As shown, a setting and releasing string is run into the designed isolation point. The string structure from bottom to top comprises a wire plug 6a, a tail pipe 6, a one-way gas injection valve 5, a hermetic seal packer 4, an annular ash injection valve 3, a releasing joint 2, and an upper end setting oil pipe 1. The annular ash injection valve 3 and the hermetic seal packer 4 are located between the upper and lower gas injection layers. The hermetic seal packer 4 is pressurized and anchored for setting according to the designed setting pressure.

[0038] S2, the upper pipe string is lost: Figure 4As shown, the matching injection valve ball is first inserted to open the one-way injection valve 5. Then, the matching release valve ball is inserted and pressure is applied to release the release joint 2, thereby releasing the upper end sealing tubing 1 and the upper tubing string. The release valve ball follows the tubing string out of the well. Alternatively, the 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, they are squeezed out by applying pressure and fall into the tail pipe 6.

[0039] S3, insert the annulus ash injection string (hereinafter referred to as the ash injection string): Figure 5 As shown in the figure, according to the design, the annular ash injection string (hereinafter referred to as the ash injection string) is composed of the ash injection pipe 8, the variable buckle joint and the upper end ash injection oil pipe 7. The outer cone 8a of the ash injection pipe 8 is inserted into the upper end bell mouth of the sheath ring 3f of the annular ash injection valve 3, and pressure is applied to cut the shear nail 3g. Figure 6 As shown, the bottom of the sheath ring 3f falls on the inner step 3c2 at the bottom of the ash injection inner tube 3c, the ash injection port 8c of the ash injection cannula 8 corresponds to the inner tube ash injection port 3c1 of the annulus ash injection valve 3, and the ash injection cannula column is in place; the upper and lower ash injection rings 8b of the ash injection cannula 8c are sealed with the inner wall of the ash injection inner tube 3c to prevent ash leakage from the upper and lower ends of the ash injection cannula 8c and the inner tube ash injection port 3c1.

[0040] S4, reverse circulation cleaning: the cleaning fluid is injected into the annulus of the oil casing. The cleaning fluid enters the inner cavity of the ash injection jacket 3b from the ash injection port 3b1 of the outer jacket of the annular ash injection valve 3, pushing the annular piston 3e to overcome the resistance of the spring 3d and move upward, exposing the ash injection port 3c1 of the inner tube. The cleaning fluid enters the inner cavity of the ash injection cannula 8 through the ash injection port 3c1 and the cannula ash injection port 8c, and then ascends to the wellhead, realizing reverse circulation and cleaning the ash injection channel.

[0041] S5, reverse circulation ash injection: Figure 7 As shown, slurry is injected into the annulus between the airtight packer 4 and the annulus injection valve 3. The slurry reaches the top of the rubber sleeve of the airtight packer 4 and then enters the inner cavity of the injection jacket 3b through the outer jacket injection port 3b1 of the annulus injection valve 3. This pushes the annular piston 3e upward, overcoming the resistance of the spring 3d. The slurry then enters the inner cavity of the injection cannula 8 through the inner tube injection port 3c1 and the cannula injection port 8c. After the set injection volume is reached, the cement slurry in the injection plug 8 reaches a predetermined height, and the injection pipe column is lifted, so that the lower end of the injection plug 8 is separated from the annular injection valve 3. The annular piston 3e is reset under the tension of the spring 3d, and the inner tube injection port 3c1 is closed. The cement slurry in the injection plug 8 falls and fills the outer circumference of the release joint 2.

[0042] S6. Positive circulation well washing: Inject cleaning fluid from the central channel, the cleaning fluid flows out from the lower port of the mortar injection plug 8, and then returns to the wellhead to clean the oil casing annulus slurry above the release joint 2.

[0043] S7. Pull out the pipe and wait for setting: Pull the cement injection pipe 8 out of the wellhead, and let the cement slurry enter and wait for setting until the casing annulus space between the release joint 2 and the rubber end of the airtight packer 4 is sealed.

[0044] S8, intubation and gas insufflation: Figure 8 As shown, a gas injection string is lowered into the cannula. The string structure from bottom to top is a gas injection cannula 10, a variable buckle joint and an upper gas injection oil pipe 9. The middle section of the gas injection cannula 10 passes through the sheath ring 3f of the annulus ash injection valve 3. The lower end of the gas injection cannula 10 is inserted into the central pipe of the airtight seal packer 4 and matches each other. A sealing ring is embedded in the outer periphery of the lower end of the gas injection cannula 10 to achieve sealing with the central pipe of the airtight seal packer 4. Then, sealed gas injection is carried out, and 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 section until the designed gas injection volume is reached.

[0045] S9. Seal the gas injection layer: Figure 9 As shown, after the lower gas injection layer section reaches the designed gas injection volume, it is sealed; the slurry is squeezed from the central channel and squeezed into the lower gas injection layer section until the set volume is reached.

[0046] S10, start the pipe and wait for solidification: Figure 10 As shown, the gas injection string is lifted up to separate the lower end of the gas injection cannula 10 from the annular ash injection valve 3, and then the well is flushed by positive circulation, the pipe is lifted, and solidification is waited to complete the plugging of the lower gas injection layer; S11, Gas injection in the upper gas injection layer: Figure 11 As shown, the position of the packer card point and the combination of the pipe string are designed according to the position of the barrier layer and the upper gas injection layer segment, and the upper gas injection layer segment adjacent to the plugging layer is used as the new lower gas injection layer segment. Return to step S1 to realize gas injection of the upper layer, and repeat this cycle to complete the gas injection and plugging of all gas injection layer segments layer by layer.

[0047] The lower end of the tail pipe of the upper layer setting and releasing pipe string can be screwed to the screw plug, and can also be inserted into the releasing joint of the next layer.

[0048] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation modes without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A carbon dioxide layer-by-layer buried pipe string, characterized in that: The invention comprises a setting and releasing tubing string extending to the bottom of the well, wherein the setting and releasing tubing string comprises, from bottom to top, a tail pipe (6), a one-way gas injection valve (5), an airtight seal packer (4), an annular ash injection valve (3), a releasing joint (2) and an upper end setting oil pipe (1); a wire plug (6a) is provided at the lower end of the tail pipe (6); the airtight seal packer (4) and the annular ash injection valve (3) are located above the lower gas injection layer section and below the upper gas injection layer section.

2. The carbon dioxide layer-by-layer storage string according to claim 1 is characterized in that: The annular space ash injection valve (3) comprises an ash injection upper joint (3a), the lower end external thread of the ash injection upper joint (3a) is screwed with a ash injection outer sleeve (3b) extending downward, the lower end internal thread of the ash injection upper joint (3a) is screwed with an ash injection inner tube (3c) extending downward, a spring (3d) is provided in the annular space between the ash injection inner tube (3c) and the ash injection outer sleeve (3b), the top of the spring (3d) abuts against the lower end surface of the ash injection upper joint (3a), 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 ash injection inner tube (3c), a plurality of outer sleeve ash injection ports (3b1) are evenly distributed on the circumference of the lower part of the ash injection outer sleeve (3b), and a plurality of inner tube ash injection ports (3c1) are evenly provided on the lower part of the ash injection inner tube (3c) and the circumference corresponding to the annular piston (3e).

3. The carbon dioxide layer-by-layer storage string according to claim 2, characterized in that: The lower inner cavity of the ash injection inner tube (3c) is provided with a sheath ring (3f) for shielding the inner tube ash injection port (3c1); the sheath ring (3f) is fixed to the inner wall of the ash injection inner tube (3c) by shear nails (3g); the upper end of the sheath ring (3f) is provided with a bell mouth; the upper and lower outer circumferences of the sheath ring (3f) are respectively embedded with sheath ring sealing rings to achieve sealing with the upper and lower inner walls of the inner tube ash injection port (3c1).

4. The carbon dioxide layer-by-layer storage string according to claim 2, characterized in that: The lower end of the putty injection outer sleeve (3b) is provided with a diameter-reducing section, and the lower end of the putty injection inner tube (3c) is inserted into the diameter-reducing section at the lower end of the putty injection outer sleeve (3b).

5. The carbon dioxide layer-by-layer storage string according to claim 3 is characterized in that: The upper and lower inner walls of the annular piston (3e) are respectively embedded with piston inner sealing rings to achieve sealing with the upper and lower outer walls of the inner tube ash injection port (3c1); the upper and lower outer walls of the annular piston (3e) are respectively embedded with piston outer sealing rings to achieve sealing with the inner wall of the ash injection jacket (3b).

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

7. The carbon dioxide layer-by-layer storage string according to claim 6, characterized in that: When the shear nails (3g) are cut, the sheath ring (3f) slides down until its bottom abuts against the bottom inner step (3c2) of the mortar injection inner pipe (3c).

8. The carbon dioxide layer-by-layer storage string according to claim 7, characterized in that: After the release joint (2) is released, the upper end sealing oil pipe (1) is pulled out, and the intubation ash injection pipe column is lowered. The intubation ash injection pipe column comprises an upper end ash injection oil pipe (7) and an ash injection intubation pipe (8). The ash injection intubation pipe (8) is connected to the lower side of the upper end ash injection oil pipe (7) through a variable buckle joint.

9. The carbon dioxide layer-by-layer storage string according to claim 8, characterized in that: The lower end of the mortar injection cannula (8) is provided with a cannula outer cone (8a), and a plurality of cannula mortar injection openings (8c) are symmetrically provided near the lower circumference of the cannula outer cone (8a) and communicate with the cannula center hole. Two cannula sealing rings (8b) are respectively embedded on the upper and lower sides of the cannula mortar injection openings (8c).

10. The carbon dioxide layer-by-layer storage string according to claim 9, characterized in that: The outer cone (8a) of the lower end of the ash injection chute (8) is inserted into the upper end bell mouth of the sheath ring (3f) of the annular ash injection valve (3) and matches each other.

11. The carbon dioxide layer-by-layer storage string according to claim 10, characterized in that: After the sheath ring (3f) falls into place, the distance between the upper end of its bell 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 plug (8) and the plug ash injection port (8c).

12. The carbon dioxide layer-by-layer storage string according to claim 11, characterized in that: After the ash injection cannula (8) is inserted into the sheath ring (3f) of the annular ash injection valve (3) and is in place, the inner tube ash injection port (3c1) and the cannula ash injection port (8c) are connected in a one-to-one correspondence.

13. The carbon dioxide layer-by-layer storage string according to claim 11, characterized in that: The outer circumferential wall where the mortar injection opening (8c) is located is provided with an mortar injection annular groove (8d). After the mortar injection mortar injection pipe (8) is inserted into the sheath ring (3f) of the annular mortar injection valve (3), each inner pipe mortar injection opening (3c1) corresponds to the mortar injection annular groove (8d).

14. The carbon dioxide layer-by-layer storage string according to claim 8, characterized in that: After the cannulated cement injection string is pulled out of the wellhead, the cannulated gas injection string is lowered. The cannulated gas injection string comprises an upper gas injection oil pipe (9) and a gas injection cannula (10). The gas injection cannula (10) is connected to the lower side of the upper gas injection oil pipe (9) via a variable buckle joint.

15. The carbon dioxide layer-by-layer storage string according to claim 14, characterized in that: The outer diameter of the gas injection cannula (10) is smaller than the inner diameter of the sheath ring (3f) of the annular ash injection valve (3).

16. The carbon dioxide layer-by-layer storage string according to claim 15, characterized in that: The middle section of the gas injection cannula (10) passes through the sheath ring (3f) of the annular ash injection valve (3), and the lower end of the gas injection cannula (10) is plugged into the central tube of the airtight seal packer (4) and matches each other, and a sealing ring is embedded in the outer periphery of the lower end of the gas injection cannula (10) to realize sealed gas injection with the central tube of the airtight seal packer (4).

17. A carbon dioxide layer-by-layer gas injection plugging method, characterized in that: The following steps are included in sequence: S1. Lower setting and releasing string: from bottom to top, it includes the plug, tail pipe, one-way gas injection valve, gas-tight packer, annulus ash injection valve, releasing joint and upper end setting tubing. The annulus ash injection valve and gas-tight packer are located between the upper and lower gas injection sections. The gas-tight packer is pressurized and set. S2, release the joint and remove the upper end sealing oil pipe; S3. Lower annulus ash injection string: from top to bottom, it includes the upper end ash injection oil pipe, variable buckle joint and ash injection cannula. The lower end of the ash injection cannula is inserted into the annulus ash injection valve to open the ash injection channel of the annulus ash injection valve. S4, reverse circulation cleaning: Inject cleaning fluid from the casing annulus, and the cleaning fluid enters the central channel from the ash injection channel of the annulus ash injection valve and flows upward to the wellhead, realizing reverse circulation and cleaning the ash injection channel; S5. Reverse circulation cement injection: Cement slurry is injected from the annulus of the casing. The slurry reaches the top of the rubber sleeve of the airtight packer and then enters the inner cavity of the cement injection cannula through the cement injection channel of the annulus cement injection valve. When the set cement injection volume is reached, the cement injection cannula is lifted up so that its lower end is separated from the annulus cement injection valve, and the cement injection channel of the annulus cement injection valve is closed. The cement slurry in the cement injection cannula 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 port of the mortar injection cannula and then returns to the wellhead to clean the mortar in the casing annulus above the release joint. S7. Pull out the pipe and wait for setting: Pull the cement injection pipe out of the wellhead and wait for the cement slurry to set until the casing annulus between the release joint and the airtight packer rubber sleeve is sealed; S8, Intubation gas injection: Insert the intubation gas injection string, which includes the upper gas injection oil pipe, the variable buckle joint and the gas injection intubation pipe from top to bottom. The lower end of the gas injection intubation pipe is inserted into the central pipe of the gas-tight packer to achieve a seal, and then inject gas into the gas injection layer section; S9. Seal the lower gas injection layer: squeeze mortar from the central hole and squeeze the mortar into the lower gas injection layer; S10, lifting the pipe and waiting for solidification: lift the gas injection pipe string to separate the lower end of the gas injection pipe from the annulus ash injection valve, then perform positive circulation to wash the well, lift the pipe and wait for solidification to complete the plugging of the lower gas injection layer.

18. The carbon dioxide layer-by-layer gas injection plugging method according to claim 17, characterized in that The following steps are also included: S11. Gas injection in the upper gas injection layer: Design the packer card point position according to the position of the upper gas injection layer, take the upper gas injection layer adjacent to the plugging layer as the new lower gas injection layer, return to step S1, implement gas injection in the upper layer, and repeat this cycle to complete gas injection and plugging of all gas injection layers layer by layer.

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