A method of carbon dioxide injection and storage in stages

Abstract

The application discloses a carbon dioxide segmented dragging and injecting sealing method, and solves the problem that the absorption of coal rock strata to carbon dioxide cannot achieve overall saturation, comprising the following steps: dividing a sealing area into multiple sealing sections, determining the theoretical sealing injection amount of carbon dioxide in each sealing section; constructing a horizontal directional drilling hole in the sealing layer and lowering a casing; forming a screen hole on the whole section casing wall in the first sealing section; completing carbon dioxide injection operation by means of a carbon dioxide segmented dragging and injecting sealing device; lifting the coiled tubing to separate the releasing hand from the injector; pushing the carbon dioxide segmented injecting sealing device to the junction of the second sealing section and the third sealing section by the coiled tubing; performing a hydraulic sand-blasting perforation operation on the casing by the jetting eye to form a screen hole on the whole section casing wall in the second sealing section; lowering the coiled tubing to drive the carbon dioxide segmented injecting sealing device to the bottom of the second sealing section; completing the carbon dioxide injection operation in the second sealing section; and completing the carbon dioxide injection in all sealing sections.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide gas geological storage technology, specifically relating to a method for segmented injection and storage of carbon dioxide. Background Technology

[0002] Carbon dioxide is a major factor contributing to global warming. In order to minimize greenhouse gas emissions and mitigate the trend of global climate change, carbon dioxide is collected or deposited and injected into underground rock structures in the form of compressed liquid for storage. Carbon dioxide geological storage technology, which reduces carbon dioxide emissions, has gradually attracted people's attention.

[0003] However, when compressed carbon dioxide is directly injected into rock formations (coal seams, sandstone, and saline aquifers) through the wellbore, the carbon dioxide exhibits a fixed migration and absorption rate within a certain range of the rock mass after phase transformation. This means that once the injected amount of carbon dioxide in the rock formation reaches a certain level, it will saturate in a localized area (the rock formation reaches its maximum absorption saturation within a certain range), forming a carbon dioxide boundary absorption zone (similar to a gas reservoir zone). This restricts the diffusion range of carbon dioxide gas. In other words, once the absorption of carbon dioxide by coal seams, sandstone, and saline aquifers reaches saturation in a localized area, it will not increase with continued carbon dioxide injection. Ultimately, this leads to a rapid decrease in the carbon dioxide gas diffusion rate, resulting in uneven and insufficient overall absorption of the rock formation, reduced absorption efficiency, and prolonged storage construction period.

[0004] In summary, the absorption of carbon dioxide by rock strata (coal seams, sandstone, and saline aquifers) cannot achieve overall saturation and uniform absorption, which greatly reduces the geological storage and utilization of carbon dioxide by rock strata and increases the construction period of carbon dioxide geological storage projects, thus requiring urgent improvement. Summary of the Invention

[0005] In view of the defects and deficiencies in the prior art, the present invention provides a method for segmented injection and storage of carbon dioxide to solve the technical problems in the prior art where the absorption of carbon dioxide by rock strata (coal seam, sandstone, saline aquifer) cannot reach overall saturation and cannot achieve uniform absorption.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for segmented carbon dioxide injection and storage, wherein the method is implemented by a segmented carbon dioxide injection and storage device, the segmented carbon dioxide injection and storage device comprising an injector, a release mechanism, an oil pipe packer and a guide head coaxially connected from back to front, and the injector having a plurality of injection holes arranged circumferentially on its upper part.

[0008] The method includes the following steps:

[0009] Step 1: Determine the carbon dioxide storage layer and the storage area within it, and divide the storage area into multiple sequentially connected storage segments, including the first storage segment, the second storage segment, ..., the Nth storage segment; determine the methane reserves in each storage segment based on the geological data obtained from previous exploration; determine the theoretical carbon dioxide storage and injection volume in each storage segment based on the methane reserves;

[0010] Step 2: Drill horizontal directional boreholes within the sealed area and run casings to secure the holes;

[0011] Step 3: Use a continuous tubing to push the carbon dioxide segmented injection and storage device to the junction of the first and second storage sections; use the jet holes to perform hydraulic sandblasting perforation on the casing to form sieve holes on the casing wall of the entire section within the first storage section.

[0012] Step 4: Lower the coiled tubing to drive the carbon dioxide segmented injection sealing device to the bottom of the first sealing section;

[0013] Step 5: Perform carbon dioxide injection until the injection volume reaches the theoretical carbon dioxide storage injection volume in the storage section, then stop the injection.

[0014] Step 6: Raise the coiled tubing, use the tubing packer to set the casing, continue raising the coiled tubing until it is released from the ejector, and pull the ejector out of the wellhead;

[0015] Step 7: Push the carbon dioxide segmented injection and storage device to the junction of the second and third storage sections using a continuous tubing; perform hydraulic sandblasting perforation on the casing using the jet holes to form sieve holes on the casing wall throughout the second storage section; lower the continuous tubing to drive the carbon dioxide segmented injection and storage device to the bottom of the second storage section.

[0016] Step 8: Repeat steps 5 and 6 to complete the carbon dioxide injection operation in the second sealing section;

[0017] This process continues until the carbon dioxide injection operation in the Nth storage section is completed.

[0018] The present invention also has the following technical features:

[0019] Specifically, the carbon dioxide sequestration layer mentioned in step 1 includes coal seams and sandstone layers.

[0020] Furthermore, a one-way valve is also provided between the oil pipe packer and the guide head.

[0021] Furthermore, the injector is connected to the coiled tubing in sequence via a centralizer and a coiled tubing connector.

[0022] Furthermore, the theoretical amount of carbon dioxide to be injected into each storage segment described in step 1 is determined by the following formula:

[0023]

[0024] In the formula:

[0025] Q1 represents the theoretical carbon dioxide storage and injection volume within the storage section, in cubic meters (m³). 3 Q2 represents the methane reserves within the storage section, in cubic meters (m³). 3 n1 is the molecular weight of CO2; n2 is the molecular weight of CH4; ρ1 is the density of CO2 gas in the storage section, in g / m³. 3 ρ2 is the density of CH4 gas in the storage section, in g / m³. 3 X represents the pore volume percentage of CH4 gas in the storage section; m1 represents the mass of CO2 gas adsorbed in the storage section, in g; m2 represents the mass of CH4 gas adsorbed in the storage section, in g; ρ f1 This is the free gas density of CO2 under equilibrium conditions, expressed in g / m³. 3 ;ρ f2 This is the free gas density of CH4 under equilibrium conditions, expressed in g / m³. 3 ;v a1 This represents the absolute adsorption capacity of CO2 gas, expressed in cm³. 3 / g;v a2 This represents the absolute adsorption capacity of CH4 gas, expressed in cm³. 3 / g;V G1 This represents the Gibbs adsorption capacity of CO2 gas, expressed in cm³. 3 / g;V G2 This represents the Gibbs adsorption capacity of CH4 gas, expressed in cm³. 3 / g, where ω is a correction factor. When the carbon dioxide storage layer is a coal seam, 0.8≤ω≤1.0, and when the carbon dioxide storage layer is a sandstone layer, 0.6≤ω≤0.9.

[0026] Furthermore, in step 3, the water jet blasting perforation operation involves a perforation pressure of 18–20 MPa and a jet displacement of 2.0–2.5 m³ / s. 3 The spraying fluid is clean water, the abrasive for perforation is quartz sand with a particle size of 40-70 mesh, and the sand ratio is 6%-8%.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] The carbon dioxide segmented injection and storage method disclosed in this invention provides a formula for the theoretical carbon dioxide injection volume in each storage segment, providing a theoretical basis for segmented carbon dioxide storage. It can effectively solve the problem of limited diffusion range of carbon dioxide gas caused by blind injection. By pre-calculating the theoretical carbon dioxide injection volume in each storage segment, reliable segmented injection and storage of carbon dioxide can be achieved within the rock stratum storage area. This ensures that the absorption of carbon dioxide in each storage segment reaches overall saturation, and that each storage segment can absorb carbon dioxide uniformly. This improves the geological efficiency of carbon dioxide storage and absorption in the rock stratum, increases the utilization of carbon dioxide in the geological storage of the rock stratum, reduces the construction cycle of carbon dioxide geological storage projects, improves construction efficiency, and reduces construction costs. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention;

[0030] Figure 2 This is a schematic diagram of the carbon dioxide segmented injection and storage device in Example 1;

[0031] Figure 3 This is a construction schematic diagram of the carbon dioxide segmented injection and storage device in Example 1.

[0032] Meaning of reference numerals in the attached diagram:

[0033] 1-Injector, 2-Release, 3-Package packer, 4-Guide head, 5-Injection port, 6-Check valve, 7-Center, 8-Continuous tubing connector, 9-Carbon dioxide storage layer, 10-First storage section, 11-Second storage section, 12-Third storage section, 13-Continuous tubing, 14-Casing, 15-Sand pool, 16-Liquid carbon dioxide storage tank. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, so that those skilled in the art can better understand the present invention.

[0035] It should be noted that in the following description, detailed descriptions of known functions and designs may obscure the main content of the invention, and these descriptions will be omitted here.

[0036] It should be noted that, unless otherwise specified, all components in this invention are components known in the prior art.

[0037] The terms “upper,” “lower,” “front,” “rear,” “top,” and “bottom” used in this invention refer to orientations or positional relationships only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. “Inner” and “outer” refer to the inner and outer contours of the corresponding components, and the above terms should not be construed as limitations on the invention.

[0038] In this invention, unless otherwise stated, 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 part; they can refer to a mechanical connection or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] The technology involved in this application is explained below:

[0040] Pore ​​volume percentage of gas: This refers to the percentage of pore volume occupied by gas in the storage section. The pores in the storage section are filled with different gases. Generally, the pore volume percentage of methane gas is 70-90%.

[0041] Example 1

[0042] In this embodiment, a closed coal mine in Chongqing is used as an example. The mining depth is less than 1000m, and it is a high-gas mine. The roof of the coal seam is an alternating layer of sandstone and mudstone, with mudstone and sandstone layers from bottom to top, the sandstone layer being thicker. According to the geological data provided by the closed mine, the in-situ gas content of the coal seam is 16-20m³. 3 The gas content of the sandstone is between 2 and 4 m³ / t, belonging to low-permeability coal seams; 3 / t, because sandstone has high permeability, this rock layer was selected as the carbon dioxide sequestration layer, and then the sequestration area was selected.

[0043] Following the above technical solutions, such as Figures 1 to 3As shown, this embodiment discloses a segmented carbon dioxide injection and storage method. This method is implemented using a segmented carbon dioxide injection and storage device, which includes an injector 1, a release mechanism 2, a pipe packer 3, and a guide head 4, all coaxially connected from back to front. The injector 1 has several injection holes 5 arranged circumferentially. A one-way valve 6 is also provided between the pipe packer 3 and the guide head 4. The injector 1 is connected to a continuous tubing via a stabilizer 7 and a continuous tubing connector 8. The continuous tubing can connect to a sand slurry pool and a liquid carbon dioxide storage tank located on the ground. During sandblasting and perforation operations, the continuous tubing can connect to a clear water pool and a sand slurry pool to deliver the injection fluid into the segmented carbon dioxide injection and storage device. During carbon dioxide injection operations, the continuous tubing can connect to a liquid carbon dioxide storage tank to deliver liquid carbon dioxide into the segmented carbon dioxide injection and storage device. The injector 1 is used for sandblasting and perforation operations, and the guide head 4 is used for guidance.

[0044] The method includes the following steps:

[0045] Step 1: Divide the storage area into multiple sequentially connected storage sections, including the first storage section 10, the second storage section 11, the third storage section 12, ..., the Nth storage section; determine the methane reserves in each storage section based on the geological data obtained from previous exploration; determine the theoretical carbon dioxide storage and injection volume in each storage section based on the methane reserves;

[0046] The theoretical carbon dioxide storage and injection volume in each storage segment is determined by the following formula:

[0047]

[0048] In the formula:

[0049] Q1 represents the theoretical carbon dioxide storage and injection volume within the storage section, in cubic meters (m³). 3 Q2 represents the methane reserves within the storage section, in cubic meters (m³). 3 n1 is the molecular weight of CO2; n2 is the molecular weight of CH4; ρ1 is the density of CO2 gas in the storage section, in g / m³. 3 ρ2 is the density of CH4 gas in the storage section, in g / m³. 3 X represents the pore volume percentage of CH4 gas in the storage section; m1 represents the mass of CO2 gas adsorbed in the storage section, in g; m2 represents the mass of CH4 gas adsorbed in the storage section, in g; ρ f1 This is the free gas density of CO2 under equilibrium conditions, expressed in g / m³. 3 It can be measured through isothermal adsorption experiments; ρ f2 This is the free gas density of CH4 under equilibrium conditions, expressed in g / m³.3 It can be measured through isothermal adsorption experiments; v a1 This represents the absolute adsorption capacity of CO2 gas, expressed in cm³. 3 / g;v a2 This represents the absolute adsorption capacity of CH4 gas, expressed in cm³. 3 / g;V G1 This represents the Gibbs adsorption capacity of CO2 gas, expressed in cm³. 3 / g, obtained using the Langmuir equation; V G2 This represents the Gibbs adsorption capacity of CH4 gas, expressed in cm³. 3 / g is obtained through the Langmuir equation, where ω is a correction coefficient. When the carbon dioxide storage layer is a coal seam, 0.8≤ω≤1.0, and when the carbon dioxide storage layer is a sandstone layer, 0.6≤ω≤0.9.

[0050] The theoretical carbon dioxide sequestration injection amount is determined by determining the methane reserves in the sequestration section. The reason is that, according to the results of isothermal adsorption experiments (conventional results), under the same coal / rock strata conditions, the adsorption intensity of carbon dioxide gas in the coal / rock strata is greater than that of methane gas. Therefore, when carbon dioxide gas is injected into the coal seam through the ground, it will take advantage of this characteristic to displace methane in the pores of the coal seam.

[0051] Step 2: Within the sealed area, horizontal directional drilling was carried out using a three-section structure, and a 139.7mm casing was run in to complete the well.

[0052] Step 3: The carbon dioxide segmented injection and storage device is pushed to the junction of the first storage section 10 and the second storage section 11 using the continuous tubing 13; the casing 14 is perforated by water jetting using the jetting hole 5 to form screen holes on the entire casing wall of the first storage section 10. The purpose of the water jetting is to establish an airflow channel between the casing 14 and the first storage section 10, in preparation for the subsequent large-volume carbon dioxide injection.

[0053] The perforation pressure for sandblasting perforation operations is 18–20 MPa, and the jet displacement is 2.0–2.5 m³ / s. 3 The spraying fluid is clean water, the abrasive for perforation is quartz sand with a particle size of 40-70 mesh, and the sand ratio is 6%-8%.

[0054] Step 4: Lower the coiled tubing 13 to drive the carbon dioxide segmented injection and sealing device to the bottom of the first sealing section 10, until the guide head 4 touches the bottom of the casing 1 and can no longer move downwards.

[0055] Step 5: Perform carbon dioxide injection until the injection volume reaches the theoretical carbon dioxide storage injection volume in the storage section, then stop the injection.

[0056] Step 6: Raise the coiled tubing 13 and pressurize it to 25 MPa. Use the tubing packer 3 to set the casing 14. Continue raising the coiled tubing 13 with a lifting force of 20 MPa until the release handle 2 disengages from the ejector 1. Remove the ejector 1 from the wellhead. That is, the release handle 2, the tubing packer 3, the one-way valve 6, and the guide head 4 form a sealing mechanism, which remains inside the casing. The sealing mechanism can prevent carbon dioxide backflow in the sealing section, achieving independent carbon dioxide sealing within the sealing section.

[0057] Step 7: Push the carbon dioxide segmented injection and storage device to the junction of the second storage section 11 and the second storage section 12 using the coiled tubing 13; perform hydraulic sandblasting perforation on the casing 14 using the jet hole 5 to form sieve holes on the entire casing wall of the second storage section 12; lower the coiled tubing 13 to drive the carbon dioxide segmented injection and storage device to the bottom of the second storage section 12;

[0058] Step 8: Repeat steps 6 and 7 to complete the carbon dioxide injection operation in the second sealing section 11;

[0059] This process continues until the carbon dioxide injection operation in the Nth storage section is completed.

[0060] As described above, this embodiment, by pre-calculating the theoretical carbon dioxide injection volume in each storage segment, enables reliable segmented injection and storage of carbon dioxide within the rock stratum storage area. This ensures that the absorption of carbon dioxide in each storage segment reaches overall saturation, and that each storage segment can absorb carbon dioxide uniformly. This improves the geological efficiency of carbon dioxide storage and absorption in the rock stratum, increases the utilization of carbon dioxide in the geological storage of the rock stratum, reduces the construction cycle of the carbon dioxide geological storage project, improves construction efficiency, and reduces construction costs.

[0061] The above-described implementation process is merely an example to clearly illustrate this application and is not intended to limit the implementation methods. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementation methods here. However, obvious variations or modifications derived therefrom are still within the protection scope of this application.

Claims

1. A method for staged injection and storage of carbon dioxide, characterized in that, The method is achieved by a carbon dioxide segmented injection and sealing device, which includes an injector (1), a release device (2), an oil pipe packer (3), and a guide head (4) connected coaxially from back to front. The injector (1) has several injection holes (5) arranged circumferentially. The method includes the following steps: Step 1: Determine the carbon dioxide storage layer and the storage area within it, and divide the storage area into multiple sequentially connected storage segments, including the first storage segment, the second storage segment, ..., the Nth storage segment; determine the methane reserves in each storage segment based on the geological data obtained from previous exploration; determine the theoretical carbon dioxide injection volume in each storage segment based on the methane reserves; Step 2: Drill horizontal directional boreholes within the sealed area and run casings to secure the holes; Step 3: Use a continuous tubing to push the carbon dioxide segmented injection and storage device to the junction of the first and second storage sections; use the jet holes to perform hydraulic sandblasting perforation on the casing to form sieve holes on the casing wall of the entire section within the first storage section. Step 4: Lower the coiled tubing to drive the carbon dioxide segmented injection sealing device to the bottom of the first sealing section; Step 5: Perform carbon dioxide injection until the injection volume reaches the theoretical carbon dioxide storage injection volume in the storage section, then stop the injection. Step 6: Raise the coiled tubing, use the tubing packer (3) to set the casing, continue to raise the coiled tubing until the release (2) is disengaged from the ejector (1), and pull the ejector (1) out of the wellhead; Step 7: Push the carbon dioxide segmented injection and storage device to the junction of the second and third storage sections using a continuous tubing; perform hydraulic sandblasting perforation on the casing using the jet holes to form sieve holes on the casing wall throughout the second storage section; lower the continuous tubing to drive the carbon dioxide segmented injection and storage device to the bottom of the second storage section. Step 8: Repeat steps 5 and 6 to complete the carbon dioxide injection operation in the second sealing section; This process continues until the carbon dioxide injection operation in the Nth storage section is completed.

2. The carbon dioxide staged injection and storage method as described in claim 1, characterized in that, The carbon dioxide sequestration layer mentioned in step 1 includes coal seams and sandstone layers.

3. The carbon dioxide staged injection and storage method as described in claim 1, characterized in that, A one-way valve (6) is also provided between the oil pipe packer (3) and the guide head (4).

4. The carbon dioxide staged injection and storage method as described in claim 1, characterized in that, The injector (1) is connected to the coiled tubing in sequence via a centralizer (7) and a coiled tubing connector (8).

5. The carbon dioxide staged injection and storage method as described in claim 1, characterized in that, The theoretical carbon dioxide storage and injection volume in each storage segment mentioned in step 1 is determined by the following formula: In the formula: Q1 represents the theoretical carbon dioxide storage and injection volume within the storage section, in cubic meters (m³). 3 Q2 represents the methane reserves within the storage section, in cubic meters (m³). 3 n1 is the molecular weight of CO2; n2 is the molecular weight of CH4; ρ1 is the density of CO2 gas in the storage section, in g / m³. 3 ρ2 is the density of CH4 gas in the storage section, in g / m³. 3 X represents the pore volume percentage of CH4 gas in the storage section; m1 represents the mass of CO2 gas adsorbed in the storage section, in g; m2 represents the mass of CH4 gas adsorbed in the storage section, in g; ρ f1 This is the free gas density of CO2 under equilibrium conditions, expressed in g / m³. 3 ; ρ f2 This is the free gas density of CH4 under equilibrium conditions, expressed in g / m³. 3 ;v a1 This represents the absolute adsorption capacity of CO2 gas, expressed in cm³. 3 / g;v a2 This represents the absolute adsorption capacity of CH4 gas, expressed in cm³. 3 / g;V G1 This represents the Gibbs adsorption capacity of CO2 gas, expressed in cm³. 3 / g;V G2 This represents the Gibbs adsorption capacity of CH4 gas, expressed in cm³. 3 / g, where ω is a correction factor. When the carbon dioxide storage layer is a coal seam, 0.8≤ω≤1.0, and when the carbon dioxide storage layer is a sandstone layer, 0.6≤ω≤0.

9.

6. The carbon dioxide staged injection and storage method as described in claim 1, characterized in that, The perforation pressure for the water jet blasting perforation operation described in step 3 is 18–20 MPa, and the jet displacement is 2.0–2.5 m³ / s. 3 The spraying fluid is clean water, the abrasive for perforation is quartz sand with a particle size of 40-70 mesh, and the sand ratio is 6%-8%.

Images