System and method for fracturing rock by filling liquid oxygen into drill hole at low pressure

Abstract

The invention discloses a system for fracturing rock by filling liquid oxygen in a drill hole at low pressure. The system comprises an outer sleeve, a liquid inlet pipe, an exhaust pipe and an ignition device, the outer sleeve is filled with comburent toilet paper, the ignition device is located at the upper end of the outer sleeve, a power line is connected to the ignition device, the liquid inlet pipe penetrates through the ignition device and the comburent toilet paper and extends into an inner cavity of the outer sleeve, the exhaust pipe is connected with the ignition device in an inserted mode, and the end of the exhaust pipe is located above the comburent toilet paper. Compared with the prior art, the device has the advantages that the safety of filling liquid oxygen to crack rocks can be improved, so that the device is more practical.

Description

Technical Field

[0001] The invention relates to the field of drilling and rock cracking systems, in particular to a system and method for rock cracking by filling liquid oxygen at low pressure in a borehole. Background Art

[0002] Fracturing gas rock expansion is a new rock expansion fracturing technology, which is safer and more environmentally friendly than traditional explosive expansion fracturing.

[0003] One end of the outer sleeve of the existing rock fracturing gas expansion device is connected to a low-temperature inflation pipe and a low-temperature exhaust pipe, and a combustion-supporting material and an ignition device are arranged inside. When the expansion fracturing is started, liquid oxygen is first introduced into the outer sleeve through the low-temperature inflation pipe, and the vaporized oxygen is discharged through the low-temperature exhaust pipe at the same time, so as to achieve the purpose of controlling the gas pressure in the outer sleeve. Then, the combustion-supporting material that absorbs the liquid oxygen is ignited by the ignition device. After the combustion-supporting material is ignited, the liquid oxygen in the closed cavity is rapidly vaporized and expanded, thereby realizing the gas expansion fracturing of the rock.

[0004] The existing technology has the following defects: (1) Since the temperature of liquid oxygen is relatively low, the outer tube is easily frozen and cracked when liquid oxygen is introduced into the outer tube. At the same time, the liquid oxygen introduced into the outer tube is heated and vaporized, and a large amount of oxygen will be discharged from the low-temperature exhaust pipe before starting; (2) The combustion-supporting material is easily damaged by moisture and becomes ineffective. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the above technical defects.

[0006] In order to solve the above problems, the technical solution of the present invention is: a low-pressure liquid oxygen filling rock fracturing system in a borehole, comprising an outer casing, a liquid inlet pipe, an exhaust pipe and an ignition device;

[0007] The outer sleeve is filled with combustible toilet paper, the ignition device is located at the upper end of the outer sleeve and is connected to a power cord, the liquid inlet pipe passes through the ignition device and the combustible toilet paper and extends into the inner cavity of the outer sleeve, the exhaust pipe is plugged into the ignition device, and its end is located above the combustible toilet paper.

[0008] Furthermore, the outer sleeve adopts a 90mm PE water hose.

[0009] Furthermore, the combustion-supporting toilet paper is toilet paper with a diameter of 75 mm and a length of 30 cm, and the number thereof is ten sections.

[0010] A method for low-pressure filling of liquid oxygen in a borehole to fracture a rock system comprises the following steps:

[0011] Step 1: Use a down-the-hole drill to drill one or more holes on the rock surface that needs to be fractured. The diameter of the hole is 90mm-115mm, and the hole depth is generally 3 meters, 6 meters, and 9 meters. The specific depth can be adjusted according to the site conditions;

[0012] Step 2: Use 10 sections of toilet paper with a diameter of 75mm and a length of 30cm. The liquid inlet pipe uses an 8mm PE pipe with the same size as the hole depth. The exhaust pipe model is the same as the liquid inlet pipe. The liquid inlet pipe is placed in the middle of the toilet paper and passed through. The bottom end is sealed, and a through hole is drilled in the middle of each section of toilet paper so that the toilet paper can fully absorb liquid oxygen when filling liquid oxygen. The ignition device is placed on the toilet paper and connected to the power cord. The exhaust pipe is placed on the top of the toilet paper section, and the other end is flush with the liquid inlet pipe;

[0013] Step 3: Use a 90mm diameter PE hose for the outer sleeve, place the prepared toilet paper segment inside the outer sleeve, and seal and tighten the two ends of the outer sleeve with cable ties, place the crack-causing pipe in the drilled hole, and backfill it with sand and soil, and fill it tightly, connect the liquid inlet pipe and the liquid storage tank, and connect the power cord of the ignition device to the detonator;

[0014] Step 4: Fill with liquid oxygen, open the booster valve of the liquid storage tank, and when the booster valve reaches a certain pressure, open the liquid outlet switch for filling. At this time, the liquid oxygen enters the fracturing tube and flows out from the small hole in the middle of the toilet paper and is absorbed in the toilet paper.

[0015] Step 5: After filling is completed, close the valve of the liquid storage tank, disconnect the connection between the liquid inlet pipe and the liquid storage tank, start the detonator, ignite the ignition device in the fracturing tube to make the combustion-supporting material burn. At this time, the liquid oxygen vaporizes and expands rapidly due to the heat, exerting force on the rock wall, thereby achieving expansion and fracturing of the rock.

[0016] The advantages of the present invention compared with the prior art are:

[0017] When the rock expands and cracks in the present invention, the device needs to be placed in the rock hole, and then liquid oxygen is injected into the tube through the low-temperature inflation tube. The oxygen generated by the vaporization of the liquid oxygen will crack the moisture-proof membrane, thereby achieving the filling of liquid oxygen to crack the rock, which is safer and more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the internal structure of a system and method for rock fracturing by low-pressure filling of liquid oxygen in a borehole according to the present invention.

[0019] As shown in the figure: 1. Outer sleeve; 2. Liquid inlet pipe; 3. Exhaust pipe; 4. Combustible toilet paper; 5. Electric ignition device; 6. Power cord. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings, wherein the same components are represented by the same reference numerals.

[0021] It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to directions in the drawings, and the words "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0023] like Figure 1 As shown, a low-pressure liquid oxygen filling rock fracturing system in a borehole includes an outer casing 1, a liquid inlet pipe 2, an exhaust pipe 3 and an ignition device 5;

[0024] The outer sleeve 1 is filled with combustible toilet paper 4, the ignition device 5 is located at the upper end of the outer sleeve 1, and is connected to a power cord 6, the liquid inlet pipe 2 passes through the ignition device 5 and the combustible toilet paper 4, and extends into the inner cavity of the outer sleeve 1, the exhaust pipe 3 is plugged into the ignition device 5, and its end is located above the combustible toilet paper 4.

[0025] Furthermore, the outer sleeve 1 is made of a 90mm PE hose.

[0026] Furthermore, the combustion-supporting toilet paper 4 is made of toilet paper with a diameter of 75 mm and a length of 30 cm, and the number thereof is ten sections.

[0027] A method for low-pressure filling of liquid oxygen in a borehole to fracture a rock system comprises the following steps:

[0028] Step 1: Use a down-the-hole drill to drill one or more holes on the rock surface that needs to be fractured. The diameter of the hole is 90mm-115mm, and the hole depth is generally 3 meters, 6 meters, and 9 meters. The specific depth can be adjusted according to the site conditions;

[0029] Step 2: Use 10 sections of toilet paper with a diameter of 75mm and a length of 30cm. The liquid inlet pipe uses an 8mm PE pipe with the same size as the hole depth. The exhaust pipe model is the same as the liquid inlet pipe. The liquid inlet pipe is placed in the middle of the toilet paper and passed through. The bottom end is sealed, and a through hole is drilled in the middle of each section of toilet paper so that the toilet paper can fully absorb liquid oxygen when filling liquid oxygen. The ignition device is placed on the toilet paper and connected to the power cord. The exhaust pipe is placed on the top of the toilet paper section, and the other end is flush with the liquid inlet pipe;

[0030] Step 3: Use a 90mm diameter PE hose for the outer sleeve, place the prepared toilet paper segment inside the outer sleeve, and seal and tighten the two ends of the outer sleeve with cable ties, place the crack-causing pipe in the drilled hole, and backfill it with sand and soil, and fill it tightly, connect the liquid inlet pipe and the liquid storage tank, and connect the power cord of the ignition device to the detonator;

[0031] Step 4: Fill with liquid oxygen, open the booster valve of the liquid storage tank, and when the booster valve reaches a certain pressure, open the liquid outlet switch for filling. At this time, the liquid oxygen enters the fracturing tube and flows out from the small hole in the middle of the toilet paper and is absorbed in the toilet paper.

[0032] Step 5: After filling is completed, close the valve of the liquid storage tank, disconnect the connection between the liquid inlet pipe and the liquid storage tank, start the detonator, ignite the ignition device in the fracturing tube to make the combustion-supporting material burn. At this time, the liquid oxygen vaporizes and expands rapidly due to the heat, exerting force on the rock wall, thereby achieving expansion and fracturing of the rock.

[0033] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A low-pressure liquid oxygen filling rock fracturing system in a borehole, characterized by: It comprises an outer sleeve (1), a liquid inlet pipe (2), an exhaust pipe (3) and an ignition device (5); The outer sleeve (1) is filled with a combustion-supporting toilet paper (4); the ignition device (5) is located at the upper end of the outer sleeve (1) and is connected to a power line (6); the liquid inlet pipe (2) passes through the ignition device (5) and the combustion-supporting toilet paper (4) and extends into the inner cavity of the outer sleeve (1); the exhaust pipe (3) is plugged into the ignition device (5) and its end is located above the combustion-supporting toilet paper (4).

2. A rock fracturing system using low-pressure liquid oxygen filling in a borehole according to claim 1, characterized in that: The outer sleeve (1) is made of a 90 mm PE hose.

3. A system and method for rock fracturing by filling a borehole with liquid oxygen at low pressure according to claim 1, characterized in that: The combustion-supporting toilet paper (4) is toilet paper with a diameter of 75 mm and a length of 30 cm, and the number of the toilet paper is ten.

4. A method for low-pressure filling of liquid oxygen in a borehole to fracture a rock system according to claims 1-3, characterized in that: The steps include: Step 1: Use a down-the-hole drill to drill one or more holes on the rock surface that needs to be fractured. The diameter of the hole is 90mm-115mm, and the hole depth is generally 3 meters, 6 meters, and 9 meters. The specific depth can be adjusted according to the site conditions; Step 2: 10 sections of toilet paper with a diameter of 75 mm and a length of 30 cm are required. The liquid inlet pipe (2) uses an 8 mm PE pipe with the same size as the hole depth. The exhaust pipe (3) is the same model as the liquid inlet pipe. The liquid inlet pipe (2) is placed in the middle of the toilet paper and passed through. The bottom end is sealed, and a through hole is drilled in the middle of each section of toilet paper so that the toilet paper can fully absorb the liquid oxygen when filling it. The ignition device (5) is placed on the toilet paper and connected to the power cord (6). The exhaust pipe is placed on the top of the toilet paper section, and the other end is flush with the liquid inlet pipe (2); Step 3: The outer sleeve (1) uses a PE hose with a diameter of 90 mm, and the prepared toilet paper segment is placed in the outer sleeve (1), and the two ends of the outer sleeve (1) are sealed and tied tightly with cable ties, the fracture-causing tube is placed in the drilled hole, and backfilled with sand and soil, and filled tightly, the liquid inlet pipe (2) and the liquid storage tank are connected, and the power line (6) of the ignition device is connected to the detonator; Step 4: Fill with liquid oxygen, open the booster valve of the liquid storage tank, and when the booster valve reaches a certain pressure, open the liquid outlet switch for filling. At this time, the liquid oxygen enters the fracturing tube and flows out from the small hole in the middle of the toilet paper and is absorbed in the toilet paper. Step 5: After filling is completed, the valve of the liquid storage tank is closed, the connection between the liquid inlet pipe (2) and the liquid storage tank is disconnected, the detonator is started, and the ignition device (5) in the fracturing tube is ignited to burn the combustion-supporting material. At this time, the liquid oxygen is rapidly vaporized and expanded by the heat, exerting force on the rock wall, thereby achieving expansion and fracturing of the rock.

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