Porous group short branch exploration treatment method based on underneath arrangement of ultra-long horizontal section sleeve

Abstract

The invention discloses a porous group short branch exploration and treatment method based on underneath arrangement of an ultra-long horizontal section sleeve, belongs to the technical field of hydrogeological drilling and coal mine water prevention and control, and aims to solve the problem of exploration and treatment of a coal seam mining bottom plate limestone water ground advanced area. The process comprises the following steps: selecting a well site and an orifice to ensure that an underground dangerous area is avoided and construction is convenient; planning a near / far-end hole group to cover a target area, limiting the distance between a near / far-end second-opening sleeve and a hole opening to be not smaller than 200m and not larger than 1000m respectively, and limiting the length of a horizontal branch hole to be not larger than 900m; main hole drilling, first-drilling / second-drilling casing pipe placement and branch hole drilling are carried out in sequence; and performing segmented pressurized-water grouting according to hole segments not larger than 300m, and monitoring grouting data. The technology achieves multiple purposes in one field, reduces the occupied area and hole sweeping amount, improves the drilling efficiency, has the grouting effect of short branch holes superior to that of long holes, and is suitable for coal mine water disaster ground area treatment.

Description

Technical Field

[0001] This invention relates to the field of hydrogeological drilling and coal mine water control technology, specifically to a multi-hole group short branch exploration and control method based on ultra-long horizontal section casing. Background Technology

[0002] In recent years, the technology for surface area control of coal mine water hazards has gradually matured and stabilized, with continuously decreasing technical barriers, driving the expansion of the application market. However, this has also intensified market competition within the industry. Against this backdrop, engineering construction prices are showing a rapid downward trend, further compressing project profit margins and posing a cost pressure challenge to the industry's development.

[0003] At the same time, with the increasingly sophisticated design methods, construction techniques, and evaluation systems in the field of ground area remediation, coupled with the successive release and implementation of various national and industry regulations, specifications, and technical standards, owners have significantly raised their requirements for engineering technical indicators and have become more stringent in controlling key technical nodes during construction, resulting in continuous upgrades to engineering implementation standards.

[0004] To further improve the effectiveness of water hazard control, surface area treatment techniques have undergone multiple iterations: from the initial "one branch hole, one water press, one grouting" to "one branch hole, segmented water press, then grouting" and "one branch hole, segmented water press test, and segmented grouting treatment." Currently, the industry clearly requires that the length of the grouting and water press section should not exceed 300m. However, while shortening the hole section can optimize the treatment effect, it leads to a sharp increase in the amount of cleaning work after grouting, which not only significantly increases the construction difficulty but also further drives up construction costs. The contradiction between project economy and treatment effect is becoming increasingly prominent.

[0005] Furthermore, the existing regional exploration and remediation projects have unreasonable planning for the length of branch boreholes during the design phase: some branch boreholes are designed to be over 1700m long. Such long branch boreholes require at least 6 segmented water pressure grouting operations, and the amount of associated borehole cleaning work is twice the amount of effective construction work, resulting in low drilling efficiency. At the same time, the grouting density at the end of long branch boreholes is insufficient due to factors such as construction technology and borehole environment, making it difficult to guarantee the remediation effect and failing to meet the current high standards of water hazard remediation. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for exploring and treating short branches in a multi-hole group based on the placement of an ultra-long horizontal section casing.

[0007] This invention discloses a method for detecting and treating short branches in a multi-hole group based on the placement of an ultra-long horizontal section casing, comprising:

[0008] Step S1: Based on the scope of the engineering target, the dominant orientation of the structural development, the distribution of underground roadways and goaf areas, determine the location of the well site, and determine at least one wellhead location within the well site;

[0009] Step S2: Based on the determined orifice locations, plan at least one set of proximal region orifice groups and at least one set of distal region orifice groups, with all the proximal region orifice groups and distal region orifice groups working together to cover the target area;

[0010] Step S3: Using the determined borehole as the drilling starting point, the main hole is drilled, the first casing is placed, the second casing is placed, and the horizontal branch hole is drilled in sequence for the near-end area hole group and the far-end area hole group. The length of all horizontal branch holes in the near-end area hole group and the far-end area hole group is no more than 900m.

[0011] Step S4: Conduct segmented water pressure tests and segmented grouting operations for each horizontal branch hole with a hole section length of no more than 300m, and monitor the grouting data simultaneously until the treatment standards are met, thus completing the water hazard investigation and treatment of the target area; the grouting data includes flow rate, cement density and grouting pressure.

[0012] As a further improvement of the present invention, in step S1, the orifice is more than 200m away from the target area; the selection of the orifice position must ensure that the drilling trajectory is far away from the underground roadway and the collapse area, and maintains a safe distance of more than 20m from the underground roadway and the goaf.

[0013] As a further improvement of the present invention, step S2 specifically includes:

[0014] Step S2.1: Based on the determined orifice location and target area, determine the number of orifice groups in the near-end region and the number of orifice groups in the far-end region;

[0015] Step S2.2: Set the planar position of the two-opening sleeve in each group of near-end area holes to be no less than 200m from the hole opening, and the planar position of the two-opening sleeve in each group of far-end area holes to be no more than 1000m from the hole opening.

[0016] Step S2.3: Set the borehole vertical ratio in the near-end region hole group and the far-end region hole group to be no greater than 2.

[0017] As a further improvement of the present invention, step S3 specifically includes:

[0018] Step S3.1: Within the selected well site, construct the near-end area borehole group and the far-end area borehole group in sequence. Each borehole group shall first carry out the first opening construction, including drilling the main hole from the ground to the specified depth and then placing the first opening casing to reinforce the shallow formation and isolate the shallow water layer.

[0019] Step S3.2: After the first section of each hole group is completed, the second section is carried out, including drilling from the bottom of the first section casing to the designed plane position of the second section casing, cleaning the hole, lowering the second section casing and completing the cementing operation to realize the lowering of the ultra-long horizontal section casing.

[0020] Step S3.3: Drill multiple horizontal branch holes from one or both sides of the two-section casing. During the drilling process, adjust the drilling trajectory according to the control points to ensure that the horizontal branch holes extend along the target layer.

[0021] As a further improvement of the present invention, in step S3.3, multiple horizontal branch holes are spaced apart along the laying direction of the two-sleeve in the near-end region hole group and the far-end region hole group, and multiple horizontal branch holes extend horizontally toward the target treatment layer and are obliquely intersecting the dominant development orientation of the fracture in the target region.

[0022] As a further improvement of the present invention, the spacing between two adjacent horizontal branch holes is 40 to 60 m.

[0023] As a further improvement of the present invention, step S4 specifically includes:

[0024] Step S4.1: Conduct segmented water pressure tests on the horizontal branch holes according to the requirement of 300m per hole segment, record the water permeability of the hole segments, and then carry out segmented grouting operations based on the test results;

[0025] Step S4.2: Verify the grouting effect by conducting a post-grouting water pressure test. If the grouting effect does not meet expectations, revise the grouting plan and perform supplementary grouting until the target area exploration and treatment is completed.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention reduces the footprint and saves costs by designing multiple borehole groups at the same well site. On the other hand, it achieves coverage of the end area by using ultra-long horizontal casing sections, controlling the effective engineering volume of the branch holes to no more than 900m and ensuring that the number of staged water pressure grouting does not exceed 3 times. This significantly reduces the amount of hole cleaning work, improves drilling efficiency, and the grouting effect of short branch holes is better than that of long branch holes, ensuring better treatment results.

[0028] This invention ensures that the distance from the borehole to the target area is greater than 200m by clearly defining the selection principle of the borehole / well site location, and that the drilling trajectory is far away from underground roadways, subsidence areas and goaf areas and maintains a safe distance of more than 20m. The construction process is not affected by underground mining, laying a safe and convenient foundation for subsequent construction. Attached Figure Description

[0029] Figure 1 This is a construction drawing of a multi-hole group short branch exploration and treatment method based on the placement of an ultra-long horizontal section casing, as disclosed in an embodiment of the present invention.

[0030] In the picture:

[0031] 1. Well site; 2. Wellhead; 3. Near-end area well group; 3.1. First horizontal branch well; 4. Far-end area well group; 4.1. Second horizontal branch well. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings:

[0036] like Figure 1 As shown, a method for detecting and treating short branches in a multi-hole group based on the placement of an ultra-long horizontal section casing according to the present invention includes:

[0037] Step S1: Based on the scope of the engineering target, the dominant orientation of the structural development, the distribution of underground roadways and goaf areas, determine the location of well site 1, and determine the location of at least one wellhead 2 within well site 1;

[0038] In step S1, the borehole 2 is more than 200m away from the target area. The selection of the location of the borehole 2 must ensure that the drilling trajectory is far away from the underground roadway and the subsidence area, and maintain a safe distance of more than 20m from the underground roadway and the goaf. The selection of the borehole 2 should prioritize flat and open terrain, far away from buildings (structures), and convenient construction area, so as to lay a safe and convenient foundation for subsequent construction.

[0039] Step S2: Based on the determined location of the orifice 2, plan at least one set of near-end area orifice group 3 and at least one set of far-end area orifice group 4, and all near-end area orifice group 3 and far-end area orifice group 4 cooperate to cover the target area.

[0040] Specifically, step S2 includes:

[0041] Step S2.1: Based on the determined location of the orifice 2 and the target area, determine the number of orifice groups 3 in the near region and orifice groups 4 in the far region;

[0042] Step S2.2: Set the planar position of the two-opening sleeve in each group of near-end region hole group 3 to be no less than 200m from the hole opening 2, and set the planar position of the two-opening sleeve in each group of far-end region hole group 4 to be no more than 1000m from the hole opening 2.

[0043] Step S2.3: Set the borehole vertical ratio in the near-end region hole group 3 and the far-end region hole group 4 to be no greater than 2.

[0044] Step S3: Using the determined borehole 2 as the starting point for drilling, the main hole is drilled, the first casing is placed, the second casing is placed, and the horizontal branch holes are drilled in the near-end area hole group 3 and the far-end area hole group 4 in sequence. The length of all horizontal branch holes in the near-end area hole group 3 and the far-end area hole group 4 is no more than 900m.

[0045] Specifically, step S3 includes:

[0046] Step S3.1: Within the selected well site 1, construct the near-end area hole group 3 and the far-end area hole group 4 in sequence. For each group of near-end area hole group 3 and far-end area hole group 4, first carry out the first-stage construction, including drilling the main hole from the ground hole 2 to the specified depth and then placing the first-stage casing to reinforce the shallow formation and isolate the shallow water layer.

[0047] Step S3.2: After the first opening of each group of boreholes 3 in the near end area and the second opening of each group of boreholes 4 in the far end area is completed, the second opening is carried out, including drilling from the bottom of the first opening casing to the designed plane position of the second opening casing, cleaning the hole, lowering the second opening casing and completing the cementing operation, so as to realize the lowering of the ultra-long horizontal section casing.

[0048] Step S3.3: Drill multiple horizontal branch holes, first horizontal branch holes 3.1, from one or both sides of the two-open casing of the near-end area hole group 3, and drill multiple horizontal branch holes, second horizontal branch holes 4.1, from one or both sides of the two-open casing of the far-end area hole group 4. During the drilling process, adjust the drilling trajectory according to the control points to ensure that the multiple first horizontal branch holes 3.1 and second horizontal branch holes 4.1 extend along the target layer.

[0049] In step S3, preferably, in the near-end region hole group 3, multiple first horizontal branch holes 3.1 are spaced apart along the laying direction of the two-sleeve in the near-end region hole group 3, and the multiple first horizontal branch holes 3.1 extend horizontally toward the target treatment layer and are obliquely intersecting the dominant development direction of fractures in the target region; in the far-end region hole group 4, multiple second horizontal branch holes 4.1 are spaced apart along the laying direction of the two-sleeve in the far-end region hole group 4, and the multiple second horizontal branch holes 4.1 extend horizontally toward the target treatment layer and are obliquely intersecting the dominant development direction of fractures in the target region.

[0050] In step S3, preferably, the orientation of the main hole and the orientation of the branch holes together constitute the drilling trajectory. The selection of the orientation of the main hole should ensure that other branch holes can be realized and cover the target area. The orientation of the main hole should ensure that the drilling on both sides can be completed smoothly. At the same time, the drilling trajectory should also be oblique to the dominant development orientation of the fracture.

[0051] In step S3, preferably, the distance between two adjacent horizontal branch holes is 40 to 60 m.

[0052] In step S3, preferably, the design of control points and target points is also included. Specifically, the design of control points and target points requires that the borehole be drilled along the target layer as much as possible. In this step, the control points are designed in the upper part of the target layer to facilitate the adjustment of the borehole trajectory during the drilling process.

[0053] In step S3, preferably, it also includes determining the fault-block strata when drilling through the fault, and adjusting the vertical trajectory by opening branches to ensure that the water inrush coefficient calculation requirements are met after treatment.

[0054] Step S4: Conduct segmented water pressure tests and segmented grouting operations for each horizontal branch hole with a hole section length of no more than 300m, and monitor the grouting data simultaneously until the treatment standards are met, thus completing the water hazard investigation and treatment of the target area. The grouting data includes flow rate, cement density, and grouting pressure.

[0055] Specifically, step S4 includes:

[0056] Step S4.1: Conduct segmented water pressure tests on the horizontal branch holes according to the requirement of 300m per hole segment, record the water permeability of the hole segments, and then carry out segmented grouting operations based on the test results;

[0057] Step S4.2: Verify the grouting effect using a post-grouting water pressure test. If the grouting effect does not meet expectations, revise the grouting plan and perform supplementary grouting until the target area exploration and treatment are completed. The grouting data includes flow rate, cement density, and grouting pressure.

[0058] Example 1

[0059] This invention has been practically applied in a regional exploration and remediation project in Huainan. The specific implementation process and results are as follows:

[0060] Well Site 1 and Orifice 2 Planning: Based on the project target scope, the advantageous orientation of the geological structure, and the distribution of underground roadways and goaf areas, a flat, open site far away from buildings and structures will be selected in this area as Well Site 1 to ensure that the construction process is not affected by underground mining, and that the drilling trajectory can avoid goaf areas and roadways and maintain a safe distance of more than 20m; the location of Orifice 2 will be determined within Well Site 1, and the distance from Orifice 2 to the target treatment area will be greater than 200m, satisfying the selection principle of Orifice 2 location.

[0061] Hole group layout design: Based on the determined wellhead 2, five hole groups are arranged within well site 1, including two near-end area hole groups 3 and three far-end area hole groups 4, ensuring that all hole groups work together to cover the entire target treatment area. Specifically, the distance from the second-stage casing plane of near-end area hole group 3 to wellhead 2 is no less than 200m, and the distance from the second-stage casing plane of far-end area hole group 4 to wellhead 2 is no more than 1000m; the borehole vertical ratio of all hole groups is preferably controlled at 1.5.

[0062] Construction of casing and branch holes:

[0063] First-stage casing construction: Taking borehole 2 as the drilling starting point, first-stage construction is carried out on all borehole groups together, drilling from the ground to the shallow stable bedrock layer, then the first-stage casing is installed and cementing is completed, forming a basic construction channel that isolates the shallow loose strata from the water layer.

[0064] Second-stage casing construction: Starting from the end of the first-stage casing, drilling proceeds towards the plane position of the second-stage casing in each near-end and far-end hole group. After reaching the design position, the hole is cleaned, the second-stage casing is installed and cemented, realizing the installation of an ultra-long horizontal section of casing, providing stable guidance for subsequent horizontal branch hole drilling.

[0065] Horizontal branch hole drilling: Horizontal branch holes are drilled from the end of the second casing of each hole group. The drilling trajectory is adjusted in conjunction with the control points to ensure that the drilling extends along the target treatment layer (coal seam floor limestone layer). The length of all horizontal branch holes is designed to be 900m.

[0066] Exploration and remediation operations:

[0067] Segmented water pressure test: Based on the standard of 300m per hole segment, segmented water pressure tests are conducted on each horizontal branch hole. Data such as water absorption and pressure changes in each hole segment are recorded to accurately determine the development of cracks and water permeability in each hole segment, and to identify areas that require key grouting.

[0068] Segmented grouting treatment: Based on the results of the water pressure test, grouting operations are carried out first on the borehole sections with high water absorption and well-developed fissures. Cement grout is used as the grouting material, and the grouting pressure is controlled to ensure that the grout fully fills the rock fissures. After each grouting section is completed, the borehole section is cleaned and then the next section of water pressure and grouting is carried out until all borehole sections are completed.

[0069] Implementation results: Under the current condition of grouting with pressurized water every 300m, the amount of hole cleaning work has been greatly reduced, drilling efficiency has been improved, and treatment effect has been enhanced, with good results in improving quality and efficiency.

[0070] The advantages of this invention are:

[0071] This invention designs multiple hole groups at the same well site 1, which reduces the footprint and saves costs. On the other hand, it uses ultra-long horizontal casing to cover the end area, controlling the effective engineering volume of the branch holes to no more than 900m and ensuring that the number of staged water pressure grouting does not exceed 3 times. This significantly reduces the amount of hole cleaning work, improves drilling efficiency, and the grouting effect of short branch holes is better than that of long branch holes, ensuring better treatment results.

[0072] This invention, by clearly defining the selection principle for the location of borehole 2 / well site 1, ensures that the distance from borehole 2 to the target area is greater than 200m, the drilling trajectory is far away from underground roadways, subsidence areas and goaf areas and maintains a safe distance of more than 20m, and the construction process is not affected by underground mining, laying a safe and convenient foundation for subsequent construction.

[0073] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting and treating short branches in a multi-hole group based on the placement of an ultra-long horizontal section casing, characterized in that, include: Step S1: Based on the scope of the engineering target, the dominant orientation of the structural development, the distribution of underground roadways and goaf areas, determine the location of the well site, and determine at least one wellhead location within the well site; Step S2: Based on the determined orifice locations, plan at least one set of proximal region orifice groups and at least one set of distal region orifice groups, with all the proximal region orifice groups and distal region orifice groups working together to cover the target area; Step S3: Using the determined borehole as the drilling starting point, the main hole is drilled, the first casing is placed, the second casing is placed, and the horizontal branch hole is drilled in sequence for the near-end area hole group and the far-end area hole group. The length of all horizontal branch holes in the near-end area hole group and the far-end area hole group is no more than 900m. Step S4: Conduct segmented water pressure tests and segmented grouting operations for each horizontal branch hole with a hole section length of no more than 300m, and monitor the grouting data simultaneously until the treatment standards are met, thus completing the water hazard investigation and treatment of the target area; the grouting data includes flow rate, cement density and grouting pressure.

2. The method for detecting and treating short branches in porous structures according to claim 1, characterized in that, In step S1, the borehole is more than 200m away from the target area; the selection of the borehole location must ensure that the drilling trajectory is far away from the underground roadway and the collapse area, and maintain a safe distance of more than 20m from the underground roadway and the goaf.

3. The method for detecting and treating short branches in porous structures according to claim 1, characterized in that, Step S2 specifically includes: Step S2.1: Based on the determined orifice location and target area, determine the number of orifice groups in the near-end region and the number of orifice groups in the far-end region; Step S2.2: Set the planar position of the two-opening sleeve in each group of near-end area holes to be no less than 200m from the hole opening, and the planar position of the two-opening sleeve in each group of far-end area holes to be no more than 1000m from the hole opening. Step S2.3: Set the borehole vertical ratio in the near-end region hole group and the far-end region hole group to be no greater than 2.

4. The method for detecting and treating short branches in porous structures according to claim 1, characterized in that, Step S3 specifically includes: Step S3.1: Within the selected well site, construct the near-end area borehole group and the far-end area borehole group in sequence. Each borehole group shall first carry out one-stage construction, including drilling the main hole from the ground to the specified depth and then placing the first-stage casing to reinforce the shallow formation and isolate the shallow water layer. Step S3.2: After the first section of each hole group is completed, the second section is carried out, including drilling from the bottom of the first section casing to the designed plane position of the second section casing, cleaning the hole, lowering the second section casing and completing the cementing operation to realize the lowering of the ultra-long horizontal section casing. Step S3.3: Drill multiple horizontal branch holes from one or both sides of the two-section casing. During the drilling process, adjust the drilling trajectory according to the control points to ensure that the horizontal branch holes extend along the target layer.

5. The method for detecting and treating short branches in porous structures according to claim 4, characterized in that, In step S3.3, multiple horizontal branch holes are spaced apart along the laying direction of the two-sleeve in the near-end area hole group and the far-end area hole group. The multiple horizontal branch holes extend horizontally toward the target treatment layer and are obliquely intersecting the dominant development direction of the fracture in the target area.

6. The method for detecting and treating short branches in porous structures according to claim 5, characterized in that, The distance between two adjacent horizontal branch holes is 40-60m.

7. The method for detecting and treating short branches in porous structures according to claim 1, characterized in that, Step S4 specifically includes: Step S4.1: Conduct segmented water pressure tests on the horizontal branch holes according to the requirement of 300m per hole segment, record the water permeability of the hole segments, and then carry out segmented grouting operations based on the test results; Step S4.2: Verify the grouting effect by conducting a post-grouting water pressure test. If the grouting effect does not meet expectations, revise the grouting plan and perform supplementary grouting until the target area exploration and treatment is completed.

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