Carbon dioxide geological storage well cementation method
By using a multi-stage cement slurry injection method and a stepped pressure control method, the problems of sealing failure and poor formation adaptability of CO2 geological storage wells were solved, achieving efficient long-term carbon dioxide storage and slowing down the leakage rate.
Patent Information
- Application Number
- CN202511312469.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-15
- Publication Date
- 2025-11-21
AI Technical Summary
In existing technologies, the cementing process for CO2 geological storage wells has a high risk of sealing failure and poor formation adaptability in long-term storage scenarios, and is prone to inducing inter-layer flow. In addition, conventional cement slurry cannot meet the sealing requirements of shallow low-pressure layers and deep high-pressure layers, and the cement stone has low density and limited resistance to CO2 erosion.
A multi-stage cement slurry injection method is adopted, which divides the annulus between the casing and the wellbore into multiple sub-annulus cavities and injects cement slurry of different densities in sequence to form multiple cement sections from bottom to top. Combined with packers and stepped pressure control, the stability and sealing of the cement sections are ensured.
It effectively prevents interlayer flow, improves cementing effect, forms dense cement stone, slows down the leakage rate of carbon dioxide, and enhances the guarantee of long-term sealing.
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Figure CN120990531A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of carbon dioxide storage, in particular to a carbon dioxide geological storage well cementing method. BACKGROUND
[0002] In the related art, the oil and gas well cementing process of the CO2 geological storage well is to inject a single cement slurry system to seal the casing and the annulus between the casing and the formation, lower the casing to the target storage layer, inject a conventional Portland cement slurry, displace the drilling fluid to achieve annular filling, and form a cement sheath under natural pressure after 48-72 hours of waiting. This method is maturely applied in oil and gas wells, but in the long-term storage scenario, the method has high risk of sealing failure, poor adaptability to the formation, and weak long-term storage guarantee. The conventional cement slurry is prone to channeling due to insufficient displacement efficiency, forming a CO2 migration channel; microannulus is generated due to cement shrinkage during the waiting period, and supercritical CO2 can seep along the gap. The single cement slurry cannot meet the sealing requirements of both shallow low-pressure layers and deep high-pressure layers, and is prone to interlayer channeling; the microfractures of the cap rock above the storage layer are not targetedly plugged, and CO2 may migrate vertically. The natural waiting pressure is insufficient, the cement stone has low density, and the anti-CO2 erosion capacity is limited. SUMMARY
[0003] The present application aims to at least partially solve one of the technical problems in the related art. To this end, an embodiment of the present application proposes a carbon dioxide geological storage well cementing method.
[0004] The carbon dioxide geological storage well cementing method according to an embodiment of the present application comprises the following steps:
[0005] S1, lowering a casing to the bottom of a wellbore, and injecting a drilling fluid into the casing;
[0006] S2, dividing the annular cavity between the casing and the wellbore into a plurality of sub-annular cavities in the up-down direction;
[0007] S3, configuring a corresponding cement slurry according to the position of the sub-annular cavity, and injecting the corresponding cement slurry into the plurality of sub-annular cavities from bottom to top through the casing, so that the plurality of sub-annular cavities form a plurality of cement segments from bottom to top, wherein the density of the cement segment located at the lower side is greater than the density of the cement segment located at the upper side.
[0008] Therefore, the carbon dioxide geological storage well cementing method according to an embodiment of the present application has strong long-term storage guarantee and can delay the seepage rate of carbon dioxide.
[0009] In some embodiments, the wellbore penetrates the shallow formation and the cap rock layer in sequence and then extends into the storage layer;
[0010] In the step S2, the plurality of sub-annular cavities include, from top to bottom, a shallow-formation annular cavity located in the shallow formation, a cap-rock annular cavity located in the cap rock, and a seal-formation annular cavity located in the seal formation.
[0011] The step S3 includes
[0012] S31, injecting a seal-formation cement slurry into the seal-formation annular cavity to form a seal-formation cement segment in the seal-formation annular cavity;
[0013] S32, injecting a cap-rock cement slurry into the cap-rock annular cavity to form a cap-rock cement segment in the cap-rock annular cavity;
[0014] S33, injecting a shallow-formation cement slurry into the shallow-formation annular cavity to form a shallow-formation cement segment in the shallow-formation annular cavity;
[0015] The steps S31, S32 and S33 are sequentially implemented.
[0016] In some embodiments, the densities of the seal-formation cement slurry, the cap-rock cement slurry and the shallow-formation cement slurry decrease sequentially.
[0017] The densities of the seal-formation cement segment, the cap-rock cement segment and the shallow-formation cement segment decrease sequentially.
[0018] In some embodiments, in the step S3, after the cement slurry is injected into the corresponding sub-annular cavity through the casing, a post-flush fluid is injected into the casing so that the post-flush fluid displaces the cement slurry to the top of the corresponding sub-annular cavity.
[0019] In some embodiments, in the step S3, when the cement slurry in the sub-annular cavity enters the waiting-on-cement period, an initial annular pressure greater than the formation pressure is applied to the cement slurry in the corresponding sub-annular cavity at the beginning of the waiting-on-cement period, and then the pressure is reduced in a preset time ladder, maintaining positive pressure throughout the cement final setting.
[0020] In some embodiments, in the step S31, the seal-formation cement slurry is injected into the seal-formation annular cavity so that the seal-formation cement slurry reaches the top of the seal-formation annular cavity;
[0021] In the step S32, the cap-rock cement slurry is injected into the cap-rock annular cavity so that the cap-rock cement slurry reaches the top of the cap-rock annular cavity;
[0022] In the step S33, the shallow-formation cement slurry is injected into the shallow-formation annular cavity so that the shallow-formation cement slurry reaches the top of the shallow-formation annular cavity.
[0023] In some embodiments, in the step S2, packers are provided at the outer periphery of the casing to sequentially divide the annular cavity between the casing and the wellbore into a plurality of the sub-annular cavities in the up-down direction.
[0024] In some embodiments, in the step S2, inflatable mechanical packers are provided at the outer periphery of the casing.
[0025] In some embodiments, in the step S3, a prepad fluid is injected into the casing before the cement slurry is injected into the casing.
[0026] In some embodiments, in the step S3, the pressure in the sub-annular cavities is monitored in real time during the cement slurry setting period in the sub-annular cavities, and the cement slurry is supplemented through the backup line when the pressure in the sub-annular cavities abnormally drops. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 is a schematic diagram of a carbon dioxide geological storage well cementing method according to an embodiment of the present application.
[0028] Reference signs: 1, casing, 2, wellbore, 3, annular cavity, 31, sub-annular cavity, 4, shallow formation, 5, cap rock, 6, storage layer, 7, shallow annular cavity, 8, cap rock annular cavity, 9, storage annular cavity, 10, packer. DETAILED DESCRIPTION
[0029] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.
[0030] A carbon dioxide geological storage well cementing method according to an embodiment of the present application is described below with reference to the drawings. As shown in Figure 1 the carbon dioxide geological storage well cementing method according to an embodiment of the present application includes the following steps:
[0031] S1, lower the casing 1 to the bottom of the wellbore 2, and inject drilling fluid into the casing 1. Specifically, the wellbore 2 extends into the storage layer 6 after sequentially passing through the shallow formation 4 and the cap rock 5 downwardly, and the casing 1 is lowered to the storage layer 6 so that carbon dioxide can be introduced into the storage layer 6 after cementing. The drilling fluid is circulated in the casing 1 and the annular cavity 3 between the casing 1 and the wellbore 2 until the density is stable, so as to clean the wellbore 2.
[0032] S2, the annular cavity 3 between the casing 1 and the wellbore 2 is sequentially divided into a plurality of sub-annular cavities 31 in the up-down direction. Specifically, in step S2, the packer 10 is arranged on the outer circumferential side of the casing 1 so as to sequentially divide the annular cavity 3 between the casing 1 and the wellbore 2 into a plurality of sub-annular cavities 31 in the up-down direction, so as to perform staged cementing, and for the sub-annular cavities 31 at different up-down positions, different cement slurries can be used for filling, so as to improve the cementing effect. For example, the inflatable mechanical packer 10 is arranged on the outer circumferential side of the casing 1.
[0033] S3, the corresponding cement slurry is configured according to the position of the sub-annular cavity 31, and the corresponding cement slurry is sequentially injected into the plurality of sub-annular cavities 31 from bottom to top through the casing 1, so that the plurality of sub-annular cavities 31 sequentially form a plurality of cement sections from bottom to top, wherein the density of the cement section located at the lower position is greater than the density of the cement section located at the upper position. That is, a plurality of cement sections are sequentially formed in the annular cavity 3 from bottom to top, and the density of the cement section located at the lower position is large, which facilitates the plurality of cement sections to stabilize the casing 1 and improves the cementing effect.
[0034] In some embodiments, in step S2, the plurality of sub-annular cavities 31 includes a shallow annular cavity 7 located at the shallow formation 4, a cap rock annular cavity 8 located at the cap rock layer 5, and a sealing annular cavity 9 located at the sealing layer 6 from top to bottom. That is, the shallow annular cavity 7, the cap rock annular cavity 8 and the sealing annular cavity 9 are sequentially arranged from bottom to top. Each of the shallow annular cavity 7, the cap rock annular cavity 8 and the sealing annular cavity 9 is a single cavity. Alternatively, each of the shallow annular cavity 7, the cap rock annular cavity 8 and the sealing annular cavity 9 is divided into a plurality of sub-cavities per packer 10.
[0035] Step S3 includes steps S31, S32 and S33, which are sequentially implemented.
[0036] In step S31, the sealing layer 6 cement slurry is injected into the sealing annular cavity 9 to form a sealing cement section in the sealing annular cavity 9. Specifically, the sealing layer cement slurry is injected into the sealing annular cavity 9 so that the sealing layer cement slurry reaches the top of the sealing annular cavity 9, so that the sealing cement section can completely fill the sealing annular cavity 9, and the overall sealing integrity is improved.
[0037] S32, the cap rock layer 5 cement slurry is injected into the cap rock annular cavity 8 to form a cap rock cement section in the cap rock annular cavity 8. Specifically, the cap rock layer cement slurry is injected into the cap rock annular cavity 8 so that the cap rock layer cement slurry reaches the top of the cap rock annular cavity 8, so that the cap rock layer cement slurry can completely fill the cap rock annular cavity 8, and the overall sealing integrity is improved.
[0038] S33, injecting shallow cement slurry into the shallow annular cavity 7 to form a shallow cement section in the shallow annular cavity 7. Specifically, the shallow cement slurry is injected into the shallow annular cavity 7 to the top of the shallow annular cavity 7, so that the shallow cement slurry can completely fill the shallow annular cavity 7, and the overall sealing integrity is improved. The densities of the sealing layer 6 cement slurry, the cap rock layer 5 cement slurry, and the shallow cement slurry decrease in turn, and the densities of the sealing cement section, the cap rock cement section, and the shallow cement section decrease in turn. For example, the shallow cement slurry and the cap rock layer cement slurry are corrosion-resistant cement slurries.
[0039] In some embodiments, in step S3, before the cement slurry is injected into the casing 1, a preflush is injected into the casing 1 to isolate the drilling fluid and the cement slurry. After the cement slurry is injected into the corresponding sub-annular cavity 31 through the casing 1, a postflush is injected into the casing 1 to displace the cement slurry to the top of the corresponding sub-annular cavity 31. In the staged displacement, the packer 10 must be activated immediately after the cement slurry in the sealing annular cavity 9 is displaced.
[0040] In some embodiments, in step S3, when the cement slurry in the sub-annular cavity 31 enters the waiting-on-cement stage, an initial annulus pressure greater than the formation pressure of the location is applied to the cement slurry in the corresponding sub-annular cavity 31 at the beginning of the waiting-on-cement stage, and then the pressure is lowered in a preset time ladder, and the positive pressure is maintained throughout the process until the cement is finally cured. Specifically, during the waiting-on-cement of the cement slurry in the sub-annular cavity 31, the pressure in the sub-annular cavity 31 is monitored in real time, and when the pressure in the sub-annular cavity 31 abnormally decreases, the cement slurry is supplemented through a standby pipeline, so that a complete cement section can be formed at the edge. The pressure supplementing operation is limited to any stage in the ladder pressure lowering process.
[0041] The carbon dioxide geological storage well cementing method according to the embodiments of the present application blocks different formations by using multiple cement slurries, prevents interlayer channeling, and inhibits the generation of microannulus by ladder pressure holding. The multiple cement sections formed by the packer 10 ensure the accurate positioning of each cement section and high displacement efficiency. The pressure monitoring and supplementing mechanism eliminates local incomplete filling defects and provides strong long-term storage protection. The high-pressure waiting-on-cement forms a dense cement stone, which delays the seepage rate of carbon dioxide.
[0042] Therefore, the carbon dioxide geological storage well cementing method according to the embodiments of the present application has strong long-term storage protection and can delay the seepage rate of carbon dioxide.
[0043] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0044] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated thereby. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.
[0045] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0046] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.
[0047] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the terminology "comprising" is used in the disclosure as comprising but not limited to, that is, it is open-ended and does not exclude the presence of additional features, structures, materials, or characteristics.
[0048] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above-described embodiments are exemplary, and are not to be interpreted as limiting the present disclosure, and the ordinary skilled in the art can make changes, modifications, replacements, and variations to the above-described embodiments within the scope of the present disclosure.
Claims
1. A cementing method for carbon dioxide geological storage wells, characterized in that, Includes the following steps: S1. Lower the casing to the bottom of the wellbore and inject drilling fluid into the casing; S2. Divide the annular cavity between the casing and the wellbore into multiple sub-annular cavities in the vertical direction; S3. According to the position of the sub-ring cavity, the corresponding cement grout is prepared, and the corresponding cement grout is injected into the multiple sub-ring cavities from bottom to top through the sleeve, so that the multiple sub-ring cavities form multiple cement segments from bottom to top, wherein the density of the cement segment located at the bottom is greater than the density of the cement segment located at the top.
2. The cementing method for carbon dioxide geological storage wells according to claim 1, characterized in that, The wellbore passes downward through shallow strata and caprock strata before extending into the sealing layer; In step S2, the plurality of sub-annular cavities include, from top to bottom, a shallow annular cavity located in the shallow strata, a caprock annular cavity located in the caprock layer, and a sealing annular cavity located in the sealing layer; Step S3 includes S31. Inject sealing layer cement slurry into the cavity of the sealing ring to form a sealing cement section in the cavity of the sealing ring; S32. Injecting caprock layer cement slurry into the caprock ring cavity to form a caprock cement section within the caprock ring cavity; S33. Inject shallow cement slurry into the shallow annular cavity to form a shallow cement section within the shallow annular cavity; Steps S31, S32, and S33 are performed sequentially.
3. The cementing method for carbon dioxide geological storage wells according to claim 2, characterized in that, The densities of the sealing layer cement slurry, the caprock layer cement slurry, and the shallow cement slurry decrease sequentially. The density of the sealed cement section, the caprock cement section, and the shallow cement section decreases sequentially.
4. The cementing method for carbon dioxide geological storage wells according to claim 2, characterized in that, In step S3, after the cement slurry is injected into the corresponding sub-ring cavity through the sleeve, a post-filling liquid is injected into the sleeve so that the post-filling liquid displaces the cement slurry to the top of the corresponding sub-ring cavity.
5. The cementing method for carbon dioxide geological storage wells according to claim 4, characterized in that, In step S3, when the cement slurry in the sub-ring cavity enters the waiting-to-set stage, in the early stage of the waiting-to-set stage, an initial annular pressure greater than the ground pressure is applied to the cement slurry in the corresponding sub-ring cavity, and then the pressure is reduced in a stepwise manner according to a preset time, maintaining positive pressure throughout the process until the cement finally sets.
6. The cementing method for carbon dioxide geological storage wells according to claim 5, characterized in that, In step S31, the sealing layer cement slurry is injected into the sealing ring cavity so that the sealing layer cement slurry reaches the top of the sealing ring cavity; In step S32, the caprock layer cement slurry is injected into the caprock ring cavity so that the caprock layer cement slurry reaches the top of the caprock ring cavity; In step S33, the shallow cement slurry is injected into the shallow annular cavity so that the shallow cement slurry reaches the top of the shallow annular cavity.
7. The cementing method for carbon dioxide geological storage wells according to claim 6, characterized in that, In step S2, a packer is provided on the outer periphery of the casing to sequentially divide the annular cavity between the casing and the wellbore into multiple sub-annular cavities in the vertical direction.
8. The cementing method for carbon dioxide geological storage wells according to claim 7, characterized in that, In step S2, an expandable mechanical packer is provided on the outer periphery of the sleeve.
9. The cementing method for carbon dioxide geological storage wells according to claim 4, characterized in that, In step S3, a pre-filled liquid is injected into the casing before the cement slurry is injected into the casing.
10. The cementing method for carbon dioxide geological storage wells according to claim 5, characterized in that, In step S3, during the setting period of the cement grout in the sub-ring cavity, the pressure in the sub-ring cavity is monitored in real time, and cement grout is injected through the backup pipeline when the pressure in the sub-ring cavity drops abnormally.