Multi-stage hole sealing method for in-situ heat injection extraction drill hole

Abstract

The invention relates to a multi-stage hole sealing method for an in-situ heat injection extraction drill hole. The technical problems that existing hole sealing is insufficient in depth and low in grouting pressure are solved. According to the technical scheme, the multi-stage hole sealing method comprises the following steps that (1) the total hole sealing length is designed according to the requirement of a roadway surrounding rock stress zone, and the total hole sealing length is divided into seven sections; (2) a grouting pipe and a grouting material are selected, the pipe diameter of the grouting pipe is smaller than the hole diameter of the drill hole, four grouting openings are formed in a first-stage plugging section of the grouting pipe, two low-pressure explosion valves are arranged on a second-stage plugging section, and a high-pressure explosion valve is arranged on a high-pressure plugging section; (3) hole sealing: a, binding a grouting pipe and a hole sealing pipe and feeding the grouting pipe and the hole sealing pipe into a drill hole; b, the four first-stage plugging sections are filled firstly, when the first-stage plugging sections are formed, the two second-stage plugging sections are filled, and when the second-stage plugging sections are formed, the second-stage plugging sections are filled; superfine cement is poured into the high-pressure plugging section to form the high-pressure plugging section; and c, the pressure for pouring the plugging material is increased step by step.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine gas extraction drilling and sealing, and particularly relates to a multi-stage sealing method for in-situ heat injection extraction drilling. Background Art

[0002] Coal mine gas extraction is a critical component of mine safety, and the reliability of the borehole sealing process directly determines the efficiency and safety of gas extraction. Currently, the industry generally adopts a "two-blocking, one-injection" bag-type sealing process, which has a sealing depth of only 6-18m and is unable to cover the original stress zone of the tunnel surrounding rock (soft rock requires 10-20m, medium-hard rock requires 5-10m, and hard rock requires 3-8m), resulting in seal failure. Existing grouting pressure uses a low-pressure setting, generally below 2MPa, making it difficult to fill deep fissures. However, the water injection pressure in in-situ heat injection extraction projects is relatively high, exceeding 2MPa. Continuing to use conventional sealing processes is difficult to meet the needs of in-situ heat injection extraction projects. A multi-stage sealing process for in-situ heat injection extraction boreholes is urgently needed. Summary of the Invention

[0003] The purpose of the present invention is to solve the technical problems of insufficient depth, low grouting pressure and inability to adapt to high temperature and high pressure environments in existing sealing, and to provide a multi-stage sealing method for in-situ heat injection and extraction drilling.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: A multi-stage sealing method for in-situ heat injection and extraction drilling, comprising the following steps: ⑴. Design sealing structure The total length of the sealing hole is designed according to the theoretical requirements of the surrounding rock stress zone of the tunnel. The total length of the sealing hole is divided into seven sections from the bottom of the borehole to the hole mouth, including 4 sections of the first-level sealing section, 2 sections of the second-level sealing section, and 1 section of the high-pressure sealing section. The distribution order of the seven sections is: the first section is the first-level sealing section (1) → the second section is the second-level sealing section (2) → the third section is the first-level sealing section (3) → the fourth section is the high-pressure sealing section (4) → the fifth section is the first-level sealing section (5) → the sixth section is the second-level sealing section (6) → the seventh section is the first-level sealing section (7); ⑵. Select grouting pipe and grouting materials The diameter of the grouting pipe is smaller than the borehole diameter, and the pressure resistance is ≥20MPa. Four grouting ports (A1-A4) with different apertures are set on the first-level plugging section of the grouting pipe, two low-pressure bursting valves (B1, B2) are set on the second-level plugging section of the grouting pipe, and one high-pressure bursting valve (C1) is set on the high-pressure plugging section of the grouting pipe; The first-level plugging section uses time-controllable rapid-setting material, the second-level plugging section uses time-controllable rapid-setting cement, and the high-pressure plugging section uses ultrafine cement; ⑶. Sealing steps a. First, tie the grouting pipe (10) and the sealing pipe (9) securely, and then smoothly feed them into the borehole (8) along with the sealing pipe (9); b. First, connect the grouting pipe (10) to the grouting pump, and then pour the quick-setting material into the four first-level plugging sections through the grouting ports (A1~A4). When the quick-setting material in the borehole solidifies but the grouting pipe has not solidified, forming the first-level plugging section, pour the quick-setting cement into the two second-level plugging sections through the low-pressure bursting valve. After the quick-setting cement enters, the borehole is initially solidified, but the grouting pipe has not solidified, forming the second-level plugging section; pour the ultrafine cement into the high-pressure plugging section through the high-pressure bursting valve to form the high-pressure plugging section; c. The pressure of the grouting plugging material is increased step by step, and the grouting flow rate is adjusted synchronously when the pressure increases to ensure that the slurry diffusion radius is controllable.

[0005] Furthermore, the total sealing length is selected to be 30m.

[0006] Furthermore, the diameters of the four grouting ports (A1-A4) with different apertures are A1>A2>A3>A4, and the diameters of the grouting ports gradually decrease to ensure a consistent grouting speed.

[0007] Furthermore, the low-pressure burst valve pressure p B1= p B2＜ High pressure burst valve pressure p C1 , grouting pressure p of the first-level plugging section A <Secondary plugging section grouting pressure p B <Grouting pressure of high pressure plugging section p C , so as to achieve a step-by-step increase in grouting pressure.

[0008] The present invention uses a grouting pipe equipped with grouting ports of different diameters and bursting valves of different bursting pressures. It uses two time-controlled plugging materials to form a two-stage plugging space, then uses ultra-fine cement to form a high-pressure plugging section. The grouting pressure is gradually increased to achieve full coverage of the original stress zone of the deep hole and high-strength sealing. It solves the technical problems of existing sealing methods such as insufficient depth, low grouting pressure, and inability to adapt to high-temperature and high-pressure environments. Compared with the background technology, the present invention has the following beneficial effects: 1. Deep hole covering: 30m sealing depth covers the original stress zone of the tunnel surrounding rock, solving the problem of shallow hole sealing failure; 2. High and low pressure coordination: Grouting pressure p in the first-level plugging section A <Secondary plugging section grouting pressure p B <Grouting pressure of high pressure plugging section p C , the grouting pressure increases step by step, significantly improving the crack filling rate and sealing strength; 3. High temperature and high pressure adaptability: Pipes and sealing designs with a temperature resistance of ≥200°C and a pressure resistance of ≥20MPa can effectively cope with thermal stress damage and coal wall leakage in in-situ heat injection environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the present invention. DETAILED DESCRIPTION

[0010] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0011] like Figure 1 As shown, a multi-stage sealing method for in-situ heat injection and extraction drilling in this embodiment includes the following steps: ⑴. Design sealing structure The total sealing length is designed based on the theoretical requirements of the surrounding rock stress zone of the tunnel. The total sealing length is divided into seven sections from the bottom of the borehole to the hole mouth, including 4 first-level sealing sections, 2 second-level sealing sections, and 1 high-pressure sealing section. The distribution order of the seven sections is: the first section is the first-level sealing section 1 → the second section is the second-level sealing section 2 → the third section is the first-level sealing section 3 → the fourth section is the high-pressure sealing section 4 → the fifth section is the first-level sealing section 5 → the sixth section is the second-level sealing section 6 → the seventh section is the first-level sealing section 7; the total sealing length in this embodiment is 30m; ⑵. Select grouting pipe and grouting materials The grouting pipe 10 has a diameter of 10 mm and a pressure resistance of ≥ 20 MPa. Four grouting ports A1, A2, A3, and A4 with different apertures are provided on the primary plugging sections 1, 3, 5, and 7 of the grouting pipe 10. Two low-pressure bursting valves B1 and B2 are provided on the secondary plugging sections 2 and 6 of the grouting pipe 10. A high-pressure bursting valve C1 is provided on the high-pressure plugging section 4 of the grouting pipe 10. The diameters of the four grouting ports A1 to A4 with different apertures are A1>A2>A3>A4, and the diameters of the grouting ports gradually decrease. The pressure of the low-pressure bursting valve is 1.0-1.5 MPa, and the pressure of the high-pressure bursting valve is not less than 4.0-6.0 MPa. The first-level plugging section uses time-controllable rapid-setting material, the second-level plugging section uses time-controllable rapid-setting cement, and the high-pressure plugging section uses ultrafine cement; ⑶. Sealing steps a. First, tie the grouting pipe 10 and the sealing pipe 9 securely, and then smoothly feed them into the borehole 8 along with the sealing pipe 9; b. First, connect the grouting pipe 10 to the grouting pump, and then pour the quick-setting material into the four primary plugging sections through the grouting ports A1~A4. When the quick-setting material in the borehole solidifies and the quick-setting material in the borehole 8 solidifies, but the grouting pipe has not solidified, forming a primary plugging section, pour the quick-setting cement into the two secondary plugging sections through the low-pressure blasting valve. After the quick-setting cement enters, the borehole is initially solidified, but the grouting pipe has not solidified, forming a secondary plugging section; pour the ultrafine cement into the high-pressure plugging section through the high-pressure blasting valve to form a high-pressure plugging section; the grouting pressure of the primary plugging section is less than 1.0 MPa, the grouting pressure of the secondary plugging section is 1.5-3.0 MPa, and the grouting pressure of the high-pressure plugging section is 6.0-10.0 MPa; c. The pressure of the grouting plugging material is increased step by step, and the grouting flow rate is adjusted synchronously when the pressure increases to ensure that the slurry diffusion radius is controllable.

Claims

1. A multi-stage sealing method for in-situ heat injection and extraction drilling, characterized in that: The following steps are involved: ⑴. Design sealing structure The total length of the sealing hole is designed according to the theoretical requirements of the surrounding rock stress zone of the tunnel. The total length of the sealing hole is divided into seven sections from the bottom of the borehole to the hole mouth, including 4 sections of the first-level sealing section, 2 sections of the second-level sealing section, and 1 section of the high-pressure sealing section. The distribution order of the seven sections is: the first section is the first-level sealing section (1) → the second section is the second-level sealing section (2) → the third section is the first-level sealing section (3) → the fourth section is the high-pressure sealing section (4) → the fifth section is the first-level sealing section (5) → the sixth section is the second-level sealing section (6) → the seventh section is the first-level sealing section (7); , select grouting pipe and grouting materials The diameter of the grouting pipe is smaller than the borehole diameter, and the pressure resistance is ≥20MPa. Four grouting ports (A1-A4) with different apertures are set on the first-level plugging section of the grouting pipe, two low-pressure bursting valves (B1, B2) are set on the second-level plugging section of the grouting pipe, and one high-pressure bursting valve (C1) is set on the high-pressure plugging section of the grouting pipe; The first-level plugging section uses time-controllable rapid-setting material, the second-level plugging section uses time-controllable rapid-setting cement, and the high-pressure plugging section uses ultrafine cement; , Sealing steps a. First, tie the grouting pipe (10) and the sealing pipe (9) securely, and then smoothly feed them into the borehole (8) along with the sealing pipe (9); b. First, connect the grouting pipe (10) to the grouting pump, and then pour the quick-setting material into the four first-level plugging sections through the grouting ports (A1~A4). When the quick-setting material in the borehole solidifies but the grouting pipe has not solidified, forming the first-level plugging section, pour the quick-setting cement into the two second-level plugging sections through the low-pressure bursting valve. After the quick-setting cement enters, the borehole is initially solidified but the grouting pipe has not solidified, forming the second-level plugging section; pour the ultrafine cement into the high-pressure plugging section through the high-pressure bursting valve, forming the high-pressure plugging section; c. The pressure of the grouting plugging material is increased step by step, and the grouting flow rate is adjusted synchronously when the pressure increases to ensure that the slurry diffusion radius is controllable.

2. The multi-stage sealing method for in-situ heat injection and extraction drilling according to claim 1, characterized in that: The total sealing length is selected to be 30m.

3. The multi-stage sealing method for in-situ heat injection and extraction drilling according to claim 1, characterized in that: The diameters of the four grouting ports (A1-A4) with different apertures are A1>A2>A3>A4, and the diameters of the grouting ports decrease gradually to ensure a consistent grouting speed.

4. The multi-stage sealing method for in-situ heat injection and extraction drilling according to claim 1, characterized in that: The low pressure burst valve pressure p B1= p B2＜ High pressure burst valve pressure p C1 , grouting pressure p of the first-level plugging section A <Secondary plugging section grouting pressure p B <Grouting pressure of high pressure plugging section p C , so as to achieve a step-by-step increase in grouting pressure.

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