Method for reducing casing damage rate of grouting hole in separation layer grouting filling project

Abstract

The invention provides a method for reducing the casing damage rate of a grouting hole of a separation layer grouting filling project, which comprises the following steps of: S1, collecting project basic data, investigating the current situations of casing damage and non-design path fluid channeling (grout runout) of grout, and analyzing and determining a plurality of main influence factors causing the casing damage; s2, aiming at the main influence factors, implementing corresponding optimization measures from at least one of four aspects of casing material performance, well cementation quality, grouting hole arrangement and grouting sequence; and S3, comparing the key performance indexes before and after the implementation of the optimization measures, and quantitatively verifying the reduction effect of the casing damage rate. By means of the method, the technical problem of the casing damage rate of the grouting holes in the separation layer grouting filling project is solved, the average service life of the grouting holes is prolonged, grouting hole blocking and grout running events caused by casing damage are reduced, the single-hole grouting amount is increased, and economic benefits are improved.

Description

Technical Field

[0001] This invention relates to the field of grouting technology for overburden separation, and in particular to a method for reducing the damage rate of grouting hole sleeves in grouting filling projects. Background Technology

[0002] As the cornerstone and safety net of my country's energy security strategy, the safe and efficient mining of coal is of paramount importance. However, while contributing energy, traditional coal mining activities have also caused significant ecological damage and land subsidence in mining areas. These surface deformations caused by mining subsidence not only seriously threaten the safety of surface buildings, infrastructure, and lives and property, but also have long-term negative impacts on regional groundwater systems and the ecological environment.

[0003] Against this backdrop, overburden separation grouting technology has become a key approach to achieving green coal mining and releasing coal resources buried under structures, railways, and water bodies. This technology, by precisely injecting filling grout (such as grout prepared from coal-based solid waste) into the separation space formed within the mining overburden, effectively supports key rock strata and slows down strata movement, thereby achieving multiple objectives such as controlling surface subsidence, protecting groundwater resources, utilizing coal gangue, and protecting the surface ecological environment. In recent years, the widespread application of this technology has yielded significant social, economic, and environmental benefits.

[0004] However, during the engineering implementation of this technology, a long-standing and urgent technical challenge has severely restricted its full effectiveness and further cost optimization: the problem of grouting hole casing damage. Under the combined effects of complex formation stress and grouting pressure, grouting hole casings often suffer from various forms of damage, such as deformation, breakage, and disengagement. Once casing damage occurs, it will trigger a series of chain engineering problems and risks: First, the grout flow channel is obstructed or altered, making it impossible to inject grout into the target layer as designed, thus failing to achieve the ideal filling effect; second, to deal with casing damage, it is often necessary to completely seal the borehole, directly shortening the service life of the grouting hole, reducing the cumulative grouting volume, and affecting the effectiveness of settlement control; more seriously, if the casing damage (especially breakage and disengagement) is located above the main critical layer, high-pressure grout can easily flow along the damaged channel to shallow formations or even the surface, causing major safety and environmental accidents such as surface grout leakage and environmental pollution. Currently, the main approach to casing damage relies on post-damage repair and treatment, which not only significantly increases engineering costs and construction time but also fails to fundamentally prevent casing damage from occurring.

[0005] Therefore, it is urgent to study and propose a method that can systematically analyze the causes of casing damage and take effective preventive measures against the main influencing factors, so as to fundamentally reduce the casing damage rate of grouting holes in the delamination grouting filling project and ensure the long-term, safe and efficient operation of the grouting project. This is of great significance for promoting the large-scale and standardized application of overburden delamination grouting technology.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for reducing the damage rate of grouting holes in delamination grouting filling projects, thereby solving at least one of the problems mentioned in the background art.

[0008] A first aspect of the present invention provides a method for reducing the damage rate of grouting hole sleeves in delamination grouting filling projects, comprising the following steps: S1. Collect basic engineering data, investigate the current status of casing damage and slurry cross-flow (slurry leakage) outside the design path, and analyze and determine the main influencing factors that lead to casing damage; S2. For the main influencing factors, implement corresponding optimization measures from at least one of the four aspects: casing material performance, cementing quality, grouting hole layout and grouting sequence; S3. Compare the key performance indicators before and after the implementation of optimization measures to quantitatively verify the effect of reducing the loss rate.

[0009] According to some embodiments, the engineering basic data includes data related to one or more of the following: boreholes, casing, and grouting volume; preferably, the engineering basic data includes one or more of the following: number of boreholes; number of casing damage problems such as deformation, misalignment, and disconnection in grouting holes; grouting period per hole; maximum grouting volume per hole; and total grouting volume.

[0010] According to some embodiments, in step S1, the key performance indicators on which the investigation of casing damage and slurry cross-flow is based include: average service life of grouting holes, the rate of hole blockage caused by casing damage, the amount of grout injected per hole, and the rate of slurry cross-flow events. Preferably, the investigation of casing damage and slurry cross-flow is conducted through borehole drilling and / or downhole television.

[0011] According to some embodiments, in step S1, the method for analyzing and determining the main influencing factors is to use a systematic analysis method that includes personnel, equipment, materials, methods, and environmental dimensions to screen multiple end factors and obtain the results; preferably, the main influencing factors include: insufficient casing steel grade, poor cementing quality of grouting holes, improper arrangement of grouting hole positions, and improper control of grouting sequence.

[0012] According to some embodiments, in step S2, the optimization measures implemented in terms of the performance of the casing material are as follows: select casing with a high steel grade, preferably upgrade the steel grade of the casing from J55 to N80 or higher.

[0013] According to some embodiments, the optimization measures implemented in step S2 in terms of cementing quality include: improving cementing construction standards and performing acoustic amplitude logging on each grouting hole to detect and ensure the continuity of cement sheath distribution and bonding quality.

[0014] According to some embodiments, in step S2, the optimization measures implemented in terms of the arrangement of grouting holes are: adopting a double plum blossom pattern of hole arrangement, and keeping the total number of holes and the average hole spacing unchanged during the optimization arrangement.

[0015] According to some embodiments, in step S2, the optimization measures implemented in terms of grouting sequence are as follows: adopting an advanced grouting method, dynamically prioritizing grouting of the grouting hole closest to the mining position according to the coal mine working face mining progress.

[0016] According to some embodiments, in step S3, the key performance indicators used for quantitative verification correspond to the indicators used in step S1 for investigating the current status of slurry cross-flow along undesigned paths. The reduction in the casing loss rate is demonstrated by comparing the changes in these indicators before and after the implementation of the measures.

[0017] According to some embodiments, in step S3, the reduction in the casing damage rate is reflected in the following combined effects: a significant extension of the average service life of the grouting hole, a reduction in the number of hole blockage events caused by casing damage, an increase in the cumulative grouting volume per hole, and a reduction in the number of grout cross-flow events that are not part of the design path.

[0018] The present invention has at least the following beneficial effects: This invention effectively reduces the casing damage rate of grouting holes in delamination grouting projects by controlling the casing steel grade, cementing quality of grouting holes, layout of grouting holes, and grouting sequence. It solves the technical problem of casing damage rate in delamination grouting projects, extends the average service life of grouting holes, reduces grouting hole blockage and grout leakage caused by casing damage, and increases the grouting volume per hole. It provides a practical technical solution for similar grouting projects and has achieved good economic and social benefits, which is an irreplaceable advantage of delamination grouting projects. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a flowchart of a method for reducing the damage rate of grouting hole sleeves in delamination grouting filling projects according to an embodiment of the present invention; Figure 2This is a statistical diagram of the grouting volume per grouting hole in an embodiment of the present invention; Figure 3 This is a statistical diagram showing the service life of the grouting holes on the working face in an embodiment of the present invention; Figure 4 This is a diagram illustrating the identification of the fracture location of the grouting hole on the working face in an embodiment of the present invention; Figure 5 This is a statistical diagram of grouting hole sleeve damage in an embodiment of the present invention; Figure 6 This is a diagram illustrating the analysis of the causes of slurry leakage in an embodiment of the present invention; Figure 7 These are the single-row main and auxiliary hole arrangement (lower half of the figure, working face I) and the double-row quincunx arrangement (upper half of the figure, working face II) in embodiments of the present invention; and Figure 8 This is a scatter plot comparing the timing and volume of grouting in an embodiment of the present invention. Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form includes the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] It should be noted that if the text uses terms such as "first" or "second", these terms are only used to distinguish similar objects and should not be interpreted as indicating or implying their relative importance, order of precedence, or implicitly indicating the number of technical features indicated. It should be understood that the data in the descriptions of "first" and "second" can be interchanged where appropriate.

[0024] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, dimensions, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference symbols placed within parentheses in this invention should not be construed as limiting the scope of the invention.

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a method for reducing the wear rate of grouting hole sleeves in delamination grouting filling projects, such as... Figure 1 As shown, it includes the following steps: Step S1. Collect basic engineering data, investigate the current status of casing damage and slurry cross-flow (i.e., slurry leakage) outside the design path, and analyze and determine the main influencing factors that cause casing damage; Step S2. For the main influencing factors, implement corresponding optimization measures from at least one of the four aspects: casing material performance, cementing quality, grouting hole layout and grouting sequence; Step S3. Compare the key performance indicators before and after the implementation of the optimization measures to quantitatively verify the effect of reducing the loss rate.

[0027] The method of this invention constructs a closed-loop engineering management model of "diagnosis → treatment → verification". First (S1), by systematically collecting data and investigating the current situation, the root causes of damage are accurately identified, changing the previous model of dealing with superficial problems based solely on experience. Second (S2), based on the diagnostic results, targeted integrated optimization is implemented from four key dimensions: materials, processes, spatial layout, and time-series coordination, rather than single-measure improvements. Finally (S3), quantitative verification is performed by comparing changes in key performance indicators, ensuring that the effectiveness of technical measures is measurable and traceable. This methodology embodies the shift from "experience-based construction" to "precision prevention and control" in modern engineering concepts.

[0028] This method establishes a standardized and replicable technical path for solving the problem of grouting loss. It systematically reduces the risk of grouting loss and, through source control, multi-dimensional intervention, and effect feedback, can stably and significantly improve the reliability and service life of grouting hole projects, thereby ensuring the safe, efficient, and economical operation of the entire delamination grouting and filling project.

[0029] In some embodiments, in step S1, the basic engineering data includes data related to one or more of the following: borehole volume, casing volume, and grouting volume. Borehole data reflects the scale of the project and geological conditions, casing data is the basis for analyzing structural performance, and grouting volume data is directly related to project efficiency and anomaly detection. Collecting this multidimensional data is to construct a comprehensive "medical record," providing solid data support for subsequent statistical analysis, correlation studies, and causal analysis.

[0030] In some embodiments, the basic engineering data includes the number of boreholes; the number of casing damage problems such as deformation, misalignment, and disconnection in the grouting holes; the grouting period for a single hole; and one or more of the maximum grouting volume for a single hole and the total grouting volume.

[0031] By standardizing and refining the data collection content, the objectivity and comprehensiveness of the current situation analysis were ensured. Based on this specific data, the frequency of hedging losses can be accurately calculated and the degree of loss can be quantified, avoiding subjective assumptions and providing irreplaceable quantitative basis for accurately identifying the main influencing factors in step S1.

[0032] In some embodiments, the key performance indicators used in step S1 to investigate the current status of casing damage and grout cross-flow along undesigned paths include: average service life of grouting holes, clogging rate due to casing damage, grouting volume per hole, and grout cross-flow event rate. These four indicators (average service life, clogging rate, grouting volume per hole, and cross-flow events) comprehensively quantify the negative impact of casing damage from time (durability), functional (availability), efficiency (filling capacity), and safety (risk control) dimensions.

[0033] In some embodiments, the investigation of casing damage and undesigned slurry cross-flow is conducted through borehole drilling and / or downhole television, either or a combination thereof. The use of borehole drilling and downhole television is intended to obtain direct and authentic downhole evidence, enabling a thorough investigation from the surface inwards.

[0034] In some embodiments, the method for analyzing and determining the main influencing factors in step S1 is to use a systematic analysis method that includes personnel, equipment, materials, methods, and environmental dimensions to screen multiple end factors.

[0035] In some embodiments, the main influencing factors include: insufficient casing steel grade, poor cementing quality of grouting holes, improper arrangement of grouting hole positions, and improper control of grouting sequence.

[0036] Through the analysis, verification, and screening of multiple end-point factors, the analysis ultimately converged to four key factors (materials, cementing, layout, and sequence). This process embodies the engineering logic of moving from "comprehensive investigation" to "grasping the key issues." Using this analytical method, we can overcome the limitations of traditional methods that attribute problems solely to geological conditions ("rings") or single construction issues, scientifically and structurally revealing the truly controllable and significant core problems. By focusing the main causes on these four aspects, subsequent optimization measures can concentrate resources and exert precise efforts to fundamentally solve the problems.

[0037] In some embodiments, the optimization measures implemented in step S2 in terms of casing material performance are: selecting casing with a high steel grade, preferably upgrading the steel grade of the casing from J55 to N80 or higher.

[0038] This measure targets the "material" factor, aiming to enhance the intrinsic strength of structural components. The casing is subjected to complex geostress (compression, bending, shear) within the grouting hole. Upgrading the steel grade from J55 to N80 or higher essentially significantly increases the casing's yield strength and burst resistance, substantially reducing the risk of plastic deformation or failure under the same geological and engineering loads.

[0039] In some embodiments, the optimization measures implemented in step S2 in terms of cementing quality include: improving cementing construction standards and performing acoustic amplitude logging on each grouting hole to detect and ensure the continuity of cement sheath distribution and bonding quality.

[0040] This measure addresses the "legal" factor by improving the boundary support conditions of the casing. The quality of the cement sheath determines whether the casing is uniformly and securely encased in the wellbore. High-quality cementing (achieved through improved construction standards) and rigorous acoustic logging verification ensure continuous and well-bonded cement sheaths. This provides uniform radial support for the casing, prevents point contact or stress concentration, and effectively isolates formation fluids, stabilizing the wellbore.

[0041] In some embodiments, the optimization measures implemented in step S2 in terms of the arrangement of grouting holes are: adopting a double plum blossom pattern of hole arrangement, and keeping the total number of holes and the average hole spacing unchanged during the optimization arrangement.

[0042] This measure targets the spatial dimension of the "law," optimizing the spatial structure of the engineering system to improve the stress environment. The "double plum blossom" arrangement is an optimized spatial grid structure. Compared to single-row or rectangular arrangements, it allows the grouting holes to be staggered on the plane without increasing the number of holes, providing more uniform support to the overlying rock strata. This guides the delamination to develop and compact more smoothly, dispersing the concentrated stress acting on individual grouting holes and their casings.

[0043] In some embodiments, the optimization measures implemented in step S2 in terms of grouting sequence are as follows: adopting an advanced grouting method, dynamically prioritizing grouting of the grouting holes closest to the mining position according to the coal mine working face mining progress.

[0044] This measure targets the time dimension of the "law," and its principle is to achieve spatiotemporal coordination and proactive control between grouting engineering and mining activities. "Advanced grouting and dynamic priority" means that grouting operations proactively follow the mining face. When mining causes the rock strata ahead to separate and open up, the nearest grouting hole is immediately filled, which can timely support the key layer, inhibit its excessive subsidence and fracture, thereby proactively controlling the magnitude and manner of overburden movement and reducing severe disturbance to the already constructed grouting holes.

[0045] In some embodiments, in step S3, the key performance indicators used for quantitative verification correspond to the indicators used in step S1 for investigating the current status of slurry cross-flow along undesigned paths. The reduction in the casing loss rate is demonstrated by comparing the changes in these indicators before and after the implementation of the measures.

[0046] To evaluate the effectiveness of a treatment plan, the same evaluation criteria used at the time of diagnosis must be employed. The indicators used in step S3 verification strictly correspond to the indicators used in the investigation in S1, ensuring the scientific rigor and fairness of the before-and-after comparison. This provides solid data support for the conclusion of "reduced hedging loss rate," forming a complete logical loop.

[0047] In some embodiments, the reduction in the casing failure rate in step S3 is reflected in the following combined effects: a significant increase in the average service life of the grouting holes, a reduction in the number of hole blockage events caused by casing failure, an increase in the cumulative grouting volume per hole, and a reduction in the number of grout cross-flow events that are not part of the design path.

[0048] The overall goal of "reducing the casing loss rate" is concretized into four directly observable comprehensive engineering benefit indicators. This represents a systematic approach from single-indicator to multi-dimensional benefit evaluation. Extended average lifespan signifies improved durability; fewer clogging events represent enhanced reliability; increased grouting volume per hole represents improved engineering efficiency; and fewer flow-through events represent reduced safety and environmental risks. Clarifying these comprehensive effects fully demonstrates the overall value of this invention. It not only solves the problem of casing loss itself but also improves the safety, economy, and environmental friendliness of the entire grouting and filling project, effectively addressing various existing engineering pain points.

[0049] The technical solution of the present invention will be described in detail below through specific embodiments, but the present invention is not limited to the following embodiments.

[0050] Example: A method for reducing the damage rate of grouting hole sleeves in delamination grouting filling projects. This embodiment uses a coal mine working face overburden separation grouting and filling project as an application scenario to illustrate the implementation process of this method. The core process of this method includes four logical stages: current situation diagnosis and data collection, cause analysis and main cause identification, implementation of targeted optimization measures, and quantitative verification of effects.

[0051] 1. First Phase: Project Status Diagnosis and Basic Data Collection This phase aims to comprehensively quantify the current status of grouting hole sleeve damage, laying a data foundation for subsequent analysis. The specific implementation is as follows: Data collection content: The system collects historical data of the target project area (such as Phase I project), mainly including: (1) Basic drilling parameters: total number of holes, hole location coordinates, hole depth; (2) Casing conditions: casing specifications (e.g., original J55 steel grade), insertion depth; (3) Record of casing damage events: Record in detail the location, quantity and time of casing deformation, breakage, tripping and other damage; (4) Grouting operation data: cumulative grouting volume per grouting hole (see...) Figure 2 ), maximum daily grouting volume per hole, and effective grouting service period per hole (the number of days from the start of grouting to failure due to casing damage or other reasons) (see...). Figure 3 ); (5) Abnormal Events: Record the number of occurrences, locations, and handling of "slurry leakage" (i.e., slurry flowing outside the designed path) events (see [reference]). Figure 4 ).

[0052] By organizing the above data, the initial loss rate can be calculated (see...). Figure 5 Key indicators such as average single-hole lifespan.

[0053] 2. Second Stage: Systematic Analysis of the Causes of Hedging Losses and Determination of Key Factors Based on data collection, this stage employs a systematic analysis method (such as...). Figure 6 As shown, the causes of the loss are analyzed layer by layer based on five dimensions: "people, machine, material, method, and environment".

[0054] End-point factors were identified: A technical team, through on-site investigation, historical data analysis, and experimental verification, compiled a list of nine end-point influencing factors. These included: personnel factors such as inadequate technical briefings and insufficient on-site construction management; machinery factors such as insufficient fastening equipment capacity; material factors such as insufficient casing steel grade and unsuitable coupling connection methods; methodological factors such as poor cementing quality of grouting holes, improper grouting hole layout, and inaccurate grouting sequence; and environmental factors such as poor geological conditions.

[0055] That is, the nine end-point influencing factors include: technical briefing and on-site management (people), equipment fastening capability (machine), casing steel grade and coupling type (material), cementing quality, borehole layout, grouting sequence (method), and geological conditions (environment).

[0056] Key Factor Screening and Identification: Through causal analysis, correlation comparison, and field test verification (e.g., comparing the deformation of casings of different steel grades), four main factors that play a decisive role in casing loss were screened from the above-mentioned end factors: (1) Insufficient casing steel grade (the original J55 steel grade has weak deformation resistance); (2) Poor cementing quality of grouting holes, incomplete cement sheath or poor bonding, resulting in uneven stress on the casing; (3) Improper arrangement of grouting holes (e.g., the original single-row arrangement failed to effectively disperse the formation stress). (4) Improper grouting sequence failed to achieve spatiotemporal coordination with the working face advancement, resulting in excessive local stratum disturbance.

[0057] 3. Third stage: Implementation of targeted optimization measures For the four main factors identified, the following integrated optimization scheme will be developed and implemented in subsequent projects (such as Phase II): Measure 1: Improve the performance of casing materials. Upgrade the steel grade of the grouting hole casing from J55 to N80 high-strength steel. N80 casing has higher yield strength and resistance to crushing, and can effectively resist the non-uniform ground stress generated by overburden movement.

[0058] Measure Two: Strengthen Cementing Quality Control. Establish higher cementing construction standards and mandate the use of acoustic amplitude logging technology to check the distribution and bonding quality of the cement sheath after cementing each well. This ensures high-quality cementing for every drilled well, while minimizing time and cost. Ensure the cement sheath is continuous and well-sealed, providing uniform radial support for the casing.

[0059] Measure 3: Optimize the spatial arrangement of grouting holes. Replace the existing single-row or simple arrangement (see...) Figure 7 (As shown in the lower half), optimized into a double plum blossom arrangement (as shown in the middle half). Figure 7 (As shown in the upper half). This arrangement, with the total number of holes remaining unchanged, makes the grouting holes staggered in the plane, which can more evenly support the overlying rock strata and disperse the concentrated stress acting on a single casing.

[0060] Measure 4: Implement dynamic advance grouting sequence. Adopt an advance grouting strategy, that is, based on the working face mining progress plan (e.g., ... Figure 8 The scatter plot shows the relationship between grouting timing and effect, dynamically prioritizing grouting of the grouting holes closest to the mining face. This allows for timely filling of the delamination space caused by mining just as it opens, providing active support for the key strata and reducing shear and tensile damage to the casing caused by uneven ground settlement.

[0061] 4. Fourth Phase: Implementation Effectiveness Check and Quantitative Verification To scientifically evaluate the effectiveness of the optimization measures, a comparison was made between the key performance indicators (KPIs) before and after implementation (Phase I and Phase II of the project): The average service life of grouting holes was significantly increased from 24.42 days / hole in Phase I to 37.2 days / hole in Phase II, thus extending the grouting window.

[0062] The number of blockage incidents caused by casing damage decreased from 14 in Phase I to 4 in Phase II, indicating a significant improvement in the stability of the grouting channel.

[0063] The average grouting volume per hole increased from 28,900 tons in Phase I to 40,800 tons in Phase II, an increase of 41.2%, significantly enhancing grouting efficiency.

[0064] Undesigned slurry cross-flow (slurry leakage) incidents: reduced from 15 in Phase I to 4 in Phase II, effectively controlling engineering safety and environmental risks.

[0065] Overall casing loss rate: Ultimately, the overall casing loss rate of the grouting holes was significantly reduced from 62.9% in Phase I to 20% in Phase II, which is better than the predetermined target of 35.3%, fully verifying the effectiveness of this integrated technical solution.

[0066] This embodiment demonstrates that through systematic current status diagnosis, scientific cause analysis, and the integrated implementation of four core technical measures—"high-grade steel casing + high-quality cementing + double-petal perforation + advanced dynamic grouting"—the casing loss rate of grouting holes in delamination grouting projects can be systematically and fundamentally reduced, thereby ensuring the long-term, safe, and efficient operation of grouting projects and yielding significant economic and social benefits.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reducing the damage rate of grouting hole sleeves in delamination grouting filling projects, characterized in that, Includes the following steps: S1. Collect basic engineering data, investigate the current status of casing damage and slurry cross-flow outside the design path, and analyze and determine the main influencing factors that lead to casing damage; S2. For the main influencing factors, implement corresponding optimization measures from at least one of the four aspects: casing material performance, cementing quality, grouting hole layout and grouting sequence; S3. Compare the key performance indicators before and after the implementation of optimization measures to quantitatively verify the effect of reducing the loss rate.

2. The method according to claim 1, characterized in that, In step S1, the engineering basic data includes data related to one or more of the drilling, casing, and grouting volumes; Preferably, the basic engineering data includes the number of boreholes; the number of casing damage problems such as deformation, misalignment, and disconnection of the grouting hole casing; the grouting period for a single hole; and one or more of the maximum grouting volume for a single hole and the total grouting volume.

3. The method according to claim 1 or 2, characterized in that, In step S1, the key performance indicators used to investigate the current status of casing damage and grout cross-flow are: average service life of grouting holes, clogging rate caused by casing damage, grouting volume per hole, and grout cross-flow event rate. Preferably, the investigation of casing damage and undesigned slurry cross-flow is conducted via borehole and / or downhole television.

4. The method according to any one of claims 1 to 3, characterized in that, In step S1, the method for analyzing and determining the main influencing factors is to use a systematic analysis method that includes personnel, equipment, materials, methods, and environment dimensions to screen multiple end factors and obtain the results. Preferably, the main influencing factors include: insufficient casing steel grade, poor cementing quality of grouting holes, improper arrangement of grouting hole positions, and improper control of grouting sequence.

5. The method according to any one of claims 1 to 4, characterized in that, In step S2, the optimization measures implemented in terms of casing material performance are as follows: select casing with high steel grade, preferably upgrade the steel grade of the casing from J55 to N80 or higher.

6. The method according to any one of claims 1 to 5, characterized in that, In step S2, optimization measures implemented in terms of cementing quality include: improving cementing construction standards and performing acoustic amplitude logging on each grouting hole to detect and ensure the continuity of cement sheath distribution and bonding quality.

7. The method according to any one of claims 1 to 6, characterized in that, In step S2, the optimization measures implemented in terms of grouting hole arrangement are as follows: adopt a double plum blossom pattern of hole arrangement, and keep the total number of holes and the average hole spacing unchanged during the optimization arrangement.

8. The method according to any one of claims 1 to 7, characterized in that, In step S2, the optimization measures implemented in terms of grouting sequence are as follows: adopt the advanced grouting method, and dynamically prioritize grouting the grouting holes closest to the mining position according to the coal mine working face mining progress.

9. The method according to any one of claims 1 to 8, characterized in that, In step S3, the key performance indicators used for quantitative verification correspond to the indicators used in step S1 to investigate the current status of slurry cross-flow along undesigned paths. The reduction in the casing loss rate is demonstrated by comparing the changes in these indicators before and after the implementation of the measures.

10. The method according to any one of claims 1 to 9, characterized in that, In step S3, the reduction in the casing damage rate is reflected in the following combined effects: a significant extension of the average service life of the grouting holes, a reduction in the number of hole blockage events caused by casing damage, an increase in the cumulative grouting volume per hole, and a reduction in the number of grout cross-flow events that are not part of the design path.

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