AU2015403840B2 - Test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of coal rock sample - Google Patents
Test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of coal rock sample Download PDFInfo
- Publication number
- AU2015403840B2 AU2015403840B2 AU2015403840A AU2015403840A AU2015403840B2 AU 2015403840 B2 AU2015403840 B2 AU 2015403840B2 AU 2015403840 A AU2015403840 A AU 2015403840A AU 2015403840 A AU2015403840 A AU 2015403840A AU 2015403840 B2 AU2015403840 B2 AU 2015403840B2
- Authority
- AU
- Australia
- Prior art keywords
- liquid nitrogen
- thawing
- freezing
- test chamber
- coal rock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Sampling And Sample Adjustment (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
A test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of a coal rock sample. The test system comprises a freeze-thawing apparatus, a data collection system, and a coal rock sample. The freeze-thawing apparatus comprises a liquid nitrogen freeze-thawing test chamber (6) and a self-pressurizing liquid nitrogen tank (7). The coal rock sample (8) is placed in the liquid nitrogen freeze-thawing test chamber (6), and the liquid nitrogen freeze-thawing test chamber (6) is connected to the self-pressurizing liquid nitrogen tank (7) by using a liquid nitrogen supply pipeline. The liquid nitrogen supply pipeline comprises a three-way connector (612), and the three-way connector (612) is respectively connected to the liquid nitrogen freeze-thawing test chamber (6), the self-pressurizing liquid nitrogen tank (7), and a liquid nitrogen pressurizing tube (610). The data collection system comprises a high-frequency pressure sensor (3), a low-temperature strain gauge (41), and a temperature sensor probe (51). The test method repeats the liquid nitrogen freeze-thawing circle for many times, to investigate influence rules on the strain and temperature of a coal rock sample (8) under different freeze-thawing variable conditions. The test method can simulate a process of permeability increase of coal body or rock body through liquid nitrogen circle freeze thawing, and provide a realizable test platform to gas or shale gas extraction from coal rock body with permeability increase by the liquid nitrogen circulation freeze thawing.
Description
Description
Test System and Method for Liquid Nitrogen Circle Freeze-Thawing Permeability-Increasing Simulation of Coal Rock Sample
Field of the Invention
The present invention relates to a system and a method for freezing-thawing test, particularly to a system and a method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample.
Background of the Invention
Statistics have shown that highly gassy mines and mines with a gas outburst risk account for about 30% among the coal mines in China, but the frequent occurrence of serious and extra serious gas accidents is not eliminated radically, which will severely hamper the safe production in the coal mines in China in the future. Hence, it is imperative to carry out coal-mine gas extraction. However, most of coal seams in China are coal seams with high gas concentration and low air permeability, where the gas extraction is difficult and the concentration of extracted gas is low, usually lower than 20%. At present, hydraulic fracturing, hydraulic cutting, presplit blasting, and the like are usually used to improve the air permeability of the coal seams. However, as the mine depth and the mining intensity increase, these conventional methods for permeability improvement gas extraction from the coal seams can achieve a fracturing and permeability improvement effect only within a small scope, and can't form a large-area gas extraction fissure network in the coal mass. Consequently, the gas extraction efficiency is low, and the gas control effect is not ideal. It is a key task to put forth an efficient method for permeability improvement gas extraction from the coal seams, in order to make a break-through in the disaster prevention and control in deep coal mining.
The freezing-thawing phenomenon is a common physico-geological function and phenomenon in the natural world, and occurs frequently, especially in object constructions in regions where the change of temperature difference is great, such as roads and buildings in Qinghai-Tibet Plateau and Northern China region. Freezing-thawing erosion is a phenomenon that the corrosion resistant stability of a soil mass or rock mass is severely degraded and the soil mass or rock mass displaces downwards along a slope under the action of gravity after the soil mass or rock mass thaws, because the the volume of moisture in the pores of the soil mass and parent material or in the fissures of the rock mass expands in frozen state, the fissures are enlarged and increased accordingly, and the entire soil mass or rock mass is fractured. The alternative occurrence of freezing and thawing of the moisture on the surface and in the interior of a structural part is referred to as freezing-thawing circulation. The repeated occurrence of the freezing-thawing circulation may cause severe damage of the object construction.
At the normal pressure, the temperature of liquid nitrogen is as low as -196°C, the latent heat of vaporization of liquid nitrogen is 5.56kJ/mol, and 1m3 of liquid nitrogen can expand into 696m3 of pure gaseous nitrogen at 21 °C, a great deal of heat is absorbed from the ambient environment when liquid nitrogen is vaporized. Liquid nitrogen has advantages such as easy preparation and wide source availability, etc. In the freezing-thawing circulation of a coal mass, liquid nitrogen can be used as an efficient refrigeration and permeability improvement medium.
In view of the drawbacks in the existing gas extraction techniques, the phase transition of liquid nitrogen may be utilized for fracturing a coal seam through cyclic freezing-thawing, and thereby a more efficient method for permeability improvement of a highly gassy coal seam can be provided , thus, providing a method for gas extraction from a coal seam based on liquid nitrogen circulation freezing-thawing permeability improvement of the coal seam in horizontal directional boreholes, which urges macroscopic fissures and microscopic fissures in a low-permeability coal seam to expand and connect with each other, under a combined action of frost heaving force resulted from phase transition of water, expansion force resulted from gasification of liquid nitrogen, and osmotic pressure of liquid flow through micro-pores, so that a fissure network for gas extraction is formed, and the air permeability of the coal seam is improved. In view that the method for gas extraction from a coal seam based on liquid nitrogen circulation freezing-thawing permeability improvement of the coal seam is influenced by many factors, it is urgent scientific problem to be solved that how to carry out research on the rule of influences of different influencing factors on the permeability improvement of a coal rock mass in laboratories, in order to provide a scientific and theoretical basis for the application of liquid nitrogen circulation freezing-thawing permeability improvement of coal seam in gas extraction projects, and determine optimal values of various influencing variables.
Contents of the Invention
Object of the invention: the object of the present invention to provide a system and a method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample, in order to provide a scientific and theoretical basis for the application of liquid nitrogen circulation freezing-thawing permeability improvement of coal seam in gas extraction projects.
To achieve the object described above, an aspect of the present invention provides a system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample, comprising: a freezing-thawing device, a data acquisition system and a coal rock sample, wherein, the freezing-thawing device comprises a liquid nitrogen freezing-thawing test chamber and a self-pressurizing liquid nitrogen container; the coal rock sample is disposed in the liquid nitrogen freezing-thawing test chamber, a heater and a liquid level sensor are arranged in the liquid nitrogen freezing-thawing test chamber, the heater is connected to a temperature controller through connecting wires of the temperature controller, the temperature controller is connected to a computer, the liquid level sensor is connected to a liquid level monitor arranged outside of the liquid nitrogen freezing-thawing test chamber, a sealing cover of liquid nitrogen freezing-thawing test chamber is arranged on the top of the liquid nitrogen freezing-thawing test chamber, a safety decompression valve, a low-temperature pressure meter, and a blow-off valve are arranged on the sealing cover of liquid nitrogen freezing-thawing test chamber, and the bottom of the liquid nitrogen freezing-thawing test chamber is connected to the self-pressurizing liquid nitrogen container through a liquid nitrogen supply pipeline.
The liquid nitrogen supply pipeline comprises a tee joint, a first end of the tee joint is connected to the bottom of the liquid nitrogen freezing-thawing test chamber, a second end of the tee joint is provided with a liquid feed/discharge valve, a third end of the tee joint is provided with a pressurizing valve, the self-pressurizing liquid nitrogen container is provided with a liquid nitrogen container stop valve which is connected to the liquid feed/discharge valve through a low-temperature resistant metal hose, a liquid nitrogen pressurizing tube is arranged outside of the liquid nitrogen freezing-thawing test chamber, the upper end of the liquid nitrogen pressurizing tube is connected to the interior of the liquid nitrogen freezing-thawing test chamber, and the lower end of the liquid nitrogen pressurizing tube is connected to the pressurizing valve.
The data acquisition system comprises a high-frequency pressure sensor, a low-temperature strain gage and a temperature sensor probe, wherein, the low-temperature strain gage and the temperature sensor probe are arranged at different positions on the coal rock sample respectively, the low-temperature strain gage is connected to a strain gauge through connecting wires of strain gauge, the temperature sensor probe is connected to a temperature sensor through connecting wires of temperature sensor, both the strain gauge and the temperature sensor are connected to the computer, the high-frequency pressure sensor is arranged inside the liquid nitrogen freezing-thawing test chamber, and is connected to the computer through a USB data cable.
Furthermore, one side of the sealing cover of liquid nitrogen freezing-thawing test chamber may be connected to the liquid nitrogen freezing-thawing test chamber via a hinge, the other side of the sealing cover of liquid nitrogen freezing-thawing test chamber may be provided with a sealing cover handle and fastening bolts, the bottom surface of the sealing cover of liquid nitrogen freezing-thawing test chamber may be arranged with a sealing groove at a position corresponding to the top of the liquid nitrogen freezing-thawing test chamber.
Furthermore, the liquid nitrogen freezing-thawing test chamber may contain a polyurethane heat insulating layer.
The method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample utilizing the test system as set forth above, in another aspect of the present invention, is as follows: in the liquid nitrogen freezing-thawing test, the liquid feed/discharge valve and the liquid nitrogen container stop valve are opened first, so that the liquid nitrogen is injected through the low-temperature resistant metal hose into the liquid nitrogen freezing-thawing test chamber, and the amount of injected liquid nitrogen is controlled by means of the liquid level monitor; when the pressure in the liquid nitrogen freezing-thawing test chamber exceeds a rated pressure, the safety decompression valve will relieves the pressure automatically to ensure the safety of the test; after the coal rock sample is frozen for a certain time in the liquid nitrogen, the liquid feed/discharge valve is opened to discharge the liquid nitrogen, the thawing temperature is set with the temperature controller, and the coal rock sample is heated by the heater so that the coal rock sample starts thawing; thus, one time of liquid nitrogen freezing-thawing circulation is completed; then, the liquid nitrogen freezing-thawing circulation described above is repeated for several times, to investigate the rule of influences on the strain and temperature of the coal rock sample under the conditions of different freezing-thawing variables, and the test data is recorded and analyzed in the computer.
Furthermore, in the investigation of the rule of the influences on the strain and temperature of the coal rock sample under the conditions of different freeze-thawing variables, first, the liquid nitrogen freezing time, thawing temperature, moisture content in sample, liquid nitrogen expansion pressure, and number of circulations may be set differently, to obtain coal rock samples that are treated for permeability improvement and fracturing under the conditions of different freeze-thawing variables; then, the obtained coal rock samples may be numbered, a change rule of mechanical characteristics of the coal rock samples may be obtained through tri-axial/uniaxial compression test and torsional shear test, a change rule of rock mass pore characteristics and micro-morphology of the coal rock samples may be obtained by means of nuclear magnetic resonance technology, ultrasonic technology, sound emission technology, scanning electron microscope technology, and CT scanning technology; finally, a quantitative analysis may be made on the change rule of mechanical characteristics of the coal rock samples and the change rule of rock mass pore characteristics and micro-morphology, to find out optimal liquid nitrogen freezing time and thawing temperature, and an influence rule of the moisture content in the samples and the number of liquid nitrogen freezing-thawing circulations in the liquid nitrogen freeze-thawing permeability improvement process of the coal rock mass.
Furthermore, in the testing process, the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber may be controlled via combination of the pressurizing valve, the liquid nitrogen pressurizing tube, and the low-temperature pressure meter, and the control process may be as follows: the pressurizing valve may be opened first, so that the liquid nitrogen in the liquid nitrogen freezing-thawing test chamber enters into the liquid nitrogen pressurizing tube, which can be a single-layer heat-conducting copper tube; the liquid nitrogen may absorb heat, expand quickly, and may be vaporized into nitrogen gas in the liquid nitrogen pressurizing tube; the nitrogen gas may enter into the liquid nitrogen freezing-thawing test chamber, the low-temperature pressure meter may displays the pressure value and controls the open/close of the pressurizing valve, so as to control the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber; the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber may be applied to the coal rock sample via the liquid nitrogen, and that is the confining pressure exerted on the coal rock sample in the testing process.
The test system and the test method provided in the present invention can simulate a process of liquid nitrogen circulation freezing-thawing permeability improvement in a coal mass or rock mass, and provide a feasible experimental platform for gas or shale gas extraction from a coal rock mass based on liquid nitrogen circulation freezing-thawing permeability improvement, can be used to carry out quantitative study on the basic parameters in liquid nitrogen freeze-thawing permeability improvement of a coal rock mass, so as to provide a scientific and theoretical basis for field experimentation of liquid nitrogen freeze-thawing.
Description of the Drawings
Embodiments will now be described by way of example only with reference to the accompanying non-limiting figures.
Fig. 1 is a schematic diagram of the system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample;
Fig. 2 is a space diagram of the liquid nitrogen freezing-thawing test chamber;
Fig. 3 is a flow chart of the method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample.
Among the figures: 1 - computer; 2 - temperature controller; 21 - heater; 22 -connecting wire of temperature controller; 3 - high-frequency pressure sensor; 31 -USB data cable; 4 - strain gauge; 41 - low-temperature strain gage; 42 - connecting wire of strain gauge; 5 - temperature sensor; 51 - temperature sensor probe; 52 -connecting wire of temperature sensor; 6 - liquid nitrogen freezing-thawing test chamber; 61 - safety decompression valve; 62 - low-temperature pressure meter; 63 - blow-off valve; 64 - sealing cover of liquid nitrogen freezing-thawing test chamber; 65 - sealing groove; 66 - sealing cover handle; 67 - fastening bolt; 68 -liquid level monitor; 69 - liquid level sensor; 610 - liquid nitrogen pressurizing tube; 611 - pressurizing valve; 612 - tee joint; 613 - liquid feed/discharge valve; 7 -self-pressurizing liquid nitrogen container; 71 - liquid nitrogen container stop valve; 72 - low-temperature resistant metal hose; 8 - coal rock sample.
Detailed Description of the Embodiments
Hereunder some embodiments of the present invention will be further detailed, with reference to the accompanying drawings.
As shown in Figs. 1 and 2, the system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample according to an embodiment of the present invention comprises a freezing-thawing device, a data acquisition system, and a coal rock sample 8.
The freezing-thawing device comprises a liquid nitrogen freezing-thawing test chamber 6 and a self-pressurizing liquid nitrogen container 7, the coal rock sample 8 is disposed in the liquid nitrogen freezing-thawing test chamber 6, the liquid nitrogen freezing-thawing test chamber 6 contains a polyurethane heat insulating layer, a heater 21 and a liquid level sensor 69 are arranged in the liquid nitrogen freezing-thawing test chamber 6, the heater 21 is connected to a temperature controller 2 through connecting wires of temperature controller 22, the temperature controller 2 is connected to a computer 1, and the liquid level sensor 69 is connected with a liquid level monitor 68 arranged outside of the liquid nitrogen freezing-thawing test chamber 6. A sealing cover 64 of liquid nitrogen freezing-thawing test chamber is arranged on the top of the liquid nitrogen freezing-thawing test chamber 6; a safety decompression valve 61, a low-temperature pressure meter 62, and a blow-off valve 63 are arranged on the sealing cover 64 of liquid nitrogen freezing-thawing test chamber, one side of the sealing cover 64 of liquid nitrogen freezing-thawing test chamber is connected to the liquid nitrogen freezing-thawing test chamber 6 via a hinge, the other side of the sealing cover 64 of liquid nitrogen freezing-thawing test chamber is provided with a sealing cover handle 66 and fastening bolts 67, and the bottom surface of the sealing cover 64 of liquid nitrogen freezing-thawing test chamber is arranged with a sealing groove 65 at a position corresponding to the top of the liquid nitrogen freezing-thawing test chamber 6. The sealing cover 64 of liquid nitrogen freezing-thawing test chamber is closed by the fastening bolts 67, and the thermal insulation of the test environment is maintained by means of the sealing groove 65; the safety decompression valve 61 will relieve pressure automatically if the pressure in the liquid nitrogen freezing-thawing test chamber 6 exceeds a rated pressure, to ensure the safety of the test; if sampling under pressure is expected, the blow-off valve 63 must be open to discharge the nitrogen pressure first, a sample can be taken out.
The bottom of the liquid nitrogen freezing-thawing test chamber 6 is connected with the self-pressurizing liquid nitrogen container 7 through a liquid nitrogen supply pipeline which comprises a tee joint 612, a first end of the tee joint 612 is connected to the bottom of the liquid nitrogen freezing-thawing test chamber 6, a second end of the tee joint 612 is provided with a liquid feed/discharge valve 613, a third end of the tee joint is provided with a pressurizing valve 611, the self-pressurizing liquid nitrogen container is provided with a liquid nitrogen container stop valve 71 which is connected to the liquid feed/discharge valve 613 through a low-temperature resistant metal hose 72, a liquid nitrogen pressurizing tube 610 is arranged outside of the liquid nitrogen freezing-thawing test chamber 6, the upper end of the liquid nitrogen pressurizing tube 610 is connected to the interior of the liquid nitrogen freezing-thawing test chamber 6, and the lower end of the liquid nitrogen pressurizing tube 610 is connected to the pressurizing valve 611. After the pressurizing valve 611 is opened, the liquid nitrogen in the liquid nitrogen freezing-thawing test chamber 6 enters into the liquid nitrogen pressurizing tube 610, exchanges heat with the environment and is vaporized; the vaporized nitrogen gas enters into the liquid nitrogen freezing-thawing test chamber 6 and is pressurized, the low-temperature pressure meter 62 displays the pressure value and controls the open/close of the pressurizing valve 611, so as to control the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber 6; the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber 6 is applied to the coal rock sample 8 via the liquid nitrogen, and that is the confining pressure exerted on the coal rock sample 8 in the testing process.
The data acquisition system comprises a high-frequency pressure sensor 3, a low-temperature strain gage 41 and a temperature sensor probe 51, wherein, the low-temperature strain gage 41 and the temperature sensor probe 51 are arranged at different positions on the coal rock sample 8 respectively, the low-temperature strain gage 41 is connected to a strain gauge 4 through connecting wires of strain gauge 42, the temperature sensor probe 51 is connected to a temperature sensor 5 through connecting wires of temperature sensor 52, both the strain gauge 4 and the temperature sensor 5 are connected to the computer 1, the high-frequency pressure sensor 3 is arranged inside the liquid nitrogen freezing-thawing test chamber 6, and is connected to the computer 1 through a USB data cable 31. The high-frequency pressure sensor 3 is configured to record the pressure change in the liquid nitrogen freezing-thawing test chamber 6, i.e., the change of the confining pressure exerted on the coal rock sample 8; the strain gauge 4 is configured to record the data of change of the strains of the coal rock sample 8 in transverse and longitudinal directions in the freezing-thawing circulation process; the temperature sensor 5 is configured to record the data of temperature change on the surface of the coal rock sample 8 and inside the coal rock sample 8.
As shown in Fig. 3, the method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample utilizing the test system described above in an embodiment of the present invention is as follows: in the liquid nitrogen freezing-thawing test, the liquid feed/discharge valve 613 and the liquid nitrogen container stop valve 71 are opened first, so that the liquid nitrogen is injected through the low-temperature resistant metal hose 72 into the liquid nitrogen freezing-thawing test chamber 6, and the injection amount of the liquid nitrogen is controlled by means of the liquid level monitor 68. In the testing process, the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber 6 is controlled via combination of the pressurizing valve 611, liquid nitrogen pressurizing tube 610, and the low-temperature pressure meter 62, the controlling process is as follows: the pressurizing valve 611 is opened first, so that the liquid nitrogen in the liquid nitrogen freezing-thawing test chamber 6 enters into the liquid nitrogen pressurizing tube 610, which is a single-layer heat-conducting copper tube; the liquid nitrogen absorbs heat, expands quickly, and is vaporized into nitrogen gas in the liquid nitrogen pressurizing tube 610; the nitrogen gas enters into the liquid nitrogen freezing-thawing test chamber 6, the low-temperature pressure meter 62 displays the pressure value and controls the open/close of the pressurizing valve 611, so as to control the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber 6; the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber 6 is applied to the coal rock sample 8 via the liquid nitrogen, and that is the confining pressure exerted on the coal rock sample 8 in the testing process. If the pressure in the freezing-thawing test chamber 6 exceeds a rated pressure, the safety decompression valve 61 will relieves the pressure automatically to ensure the safety of the test; after the coal rock sample 8 is frozen in liquid nitrogen for a certain time, the liquid feed/discharge valve 613 is opened to discharge the liquid nitrogen; the thawing temperature is set via the temperature controller 2, and the coal rock sample 8 is heated up by the heater 21, so that the coal rock sample 8 starts thawing; thus, one time of liquid nitrogen freezing-thawing circulation is completed; then, the liquid nitrogen freezing-thawing circulation is repeated for several times, to investigate the rule of influences on the strain and temperature of the coal rock sample 8 under the conditions of different freezing-thawing variables, and the test data is recorded and analyzed in the computer 1.
In the investigation of the rule of the influences on the strain and temperature of the coal rock sample 8 under the conditions of different freeze-thawing variables, first, the liquid nitrogen freezing time, thawing temperature, moisture content, liquid nitrogen expansion pressure, and number of circulations are set differently, to obtain coal rock samples 8 that are treated for permeability improvement and fracturing under the conditions of different freeze-thawing variables; then, the obtained coal rock samples 8 are numbered, a change rule of mechanical characteristics of the coal rock samples 8 is obtained through tri-axial/uniaxial compression test and torsional shear test, a change rule of rock mass pore characteristics and micro-morphology of the coal rock samples 8 is obtained by means of nuclear magnetic resonance technology, ultrasonic technology, sound emission technology, scanning electron microscope technology, and CT scanning technology; finally, a quantitative analysis is made on the change rule of mechanical characteristics of the coal rock samples 8 and the change rule of rock mass pore characteristics and micro-morphology , to find out optimal liquid nitrogen freezing time and thawing temperature, and an influence rule of the moisture content in the coal rock samples 8 and the number of liquid nitrogen freezing-thawing circulations in the liquid nitrogen freeze-thawing permeability improvement process of the coal rock mass.
The above mentioned is just some preferred embodiments of the present invention. Those skilled in the art should recognize that various variations and modifications can be made without departing from the spirit of the present invention. All of such variations and modifications shall be deemed as falling into the protected scope of the present invention.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Claims (6)
- Claims1. A system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample, comprising a freezing-thawing device, a data acquisition system, and a coal rock sample, wherein, the freezing-thawing device comprises a liquid nitrogen freezing-thawing test chamber and a self-pressurizing liquid nitrogen container; the coal rock sample is disposed in the liquid nitrogen freezing-thawing test chamber, a heater and a liquid level sensor are arranged in the liquid nitrogen freezing-thawing test chamber, the heater is connected to a temperature controller through connecting wires of temperature controller, the temperature controller is connected to a computer, the liquid level sensor is connected to a liquid level monitor arranged outside of the liquid nitrogen freezing-thawing test chamber, a sealing cover of liquid nitrogen freezing-thawing test chamber is arranged on the top of the liquid nitrogen freezing-thawing test chamber, a safety decompression valve, a low-temperature pressure meter, and a blow-off valve are arranged on the sealing cover of liquid nitrogen freezing-thawing test chamber, and the bottom of the liquid nitrogen freezing-thawing test chamber is connected to the self-pressurizing liquid nitrogen container through a liquid nitrogen supply pipeline; the liquid nitrogen supply pipeline comprises a tee joint, a first end of the tee joint is connected to the bottom of the liquid nitrogen freezing-thawing test chamber, a second end of the tee joint is provided with a liquid feed/discharge valve, a third end of the tee joint is provided with a pressurizing valve, the self-pressurizing liquid nitrogen container is provided with a liquid nitrogen container stop valve which is connected to the liquid feed/discharge valve through a low-temperature resistant metal hose, a liquid nitrogen pressurizing tube is arranged outside of the liquid nitrogen freezing-thawing test chamber, the upper end of the liquid nitrogen pressurizing tube is connected to the interior of the liquid nitrogen freezing-thawing test chamber, and the lower end of the liquid nitrogen pressurizing tube is connected to the pressurizing valve; the data acquisition system comprises a high-frequency pressure sensor, a low-temperature strain gage and a temperature sensor probe, the low-temperature strain gage and the temperature sensor probe are arranged at different positions on the coal rock sample respectively, the low-temperature strain gage is connected to a strain gauge through connecting wires of strain gauge, the temperature sensor probe is connected to a temperature sensor through connecting wires of temperature sensor, both the strain gauge and the temperature sensor are connected to the computer, the high-frequency pressure sensor is arranged inside the liquid nitrogen freezing-thawing test chamber, and is connected to the computer through a USB data cable.
- 2. The system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample according to claim 1, wherein, one side of the sealing cover of liquid nitrogen freezing-thawing test chamber is connected to the liquid nitrogen freezing-thawing test chamber via a hinge, the other side of the sealing cover of liquid nitrogen freezing-thawing test chamber is provided with a sealing cover handle and fastening bolts, the bottom surface of the sealing cover of liquid nitrogen freezing-thawing test chamber is arranged with a sealing groove at a position corresponding to the top of the liquid nitrogen freezing-thawing test chamber.
- 3. The system for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample according to claim 1 or 2, wherein, the liquid nitrogen freezing-thawing test chamber contains a polyurethane heat insulating layer.
- 4. A method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample, utilizing the test system according to any one of claims 1-3, comprising: opening the liquid feed/discharge valve and the liquid nitrogen container stop valve first in the liquid nitrogen freezing-thawing test so that the liquid nitrogen is injected through the low-temperature resistant metal hose into the liquid nitrogen freezing-thawing test chamber, and controlling the amount of injected liquid nitrogen by means of the liquid level monitor; relieving the pressure via the safety decompression valve automatically to ensure the safety of the test, if the pressure in the liquid nitrogen freezing-thawing test chamber exceeds a rated pressure; opening the liquid feed/discharge valve to discharge the liquid nitrogen after the coal rock sample is frozen for a certain time in the liquid nitrogen, setting the thawing temperature with the temperature controller, and heating up the coal rock sample with the heater so that the coal rock sample starts thawing; thus, one time of liquid nitrogen freezing-thawing circulation is completed; then, repeating the liquid nitrogen freezing-thawing circulation for several times, to investigate the rule of influences on the strain and temperature of the coal rock sample under the conditions of different freezing-thawing variables, and recording and analyzing the test data in the computer.
- 5. The method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample according to claim 4, wherein, in the investigation of the rule of the influences on the strain and temperature of the coal rock sample under the conditions of different freeze-thawing variables, first, the liquid nitrogen freezing time, thawing temperature, moisture content, liquid nitrogen expansion pressure, and number of circulations are set differently, to obtain coal rock samples that are treated for permeability improvement and fracturing under the conditions of different freeze-thawing variables; then, the obtained coal rock samples are numbered, a change rule of mechanical characteristics of the coal rock samples is obtained through tri-axial/uniaxial compression test and torsional shear test, a change rule of rock mass pore characteristics and micro-morphology of the coal rock samples is obtained by means of nuclear magnetic resonance technology, ultrasonic technology, sound emission technology, scanning electron microscope technology, and CT scanning technology; finally, a quantitative analysis is made on the change rule of mechanical characteristics of the coal rock samples and the change rule of rock mass pore characteristics and micro-morphology, to find out optimal liquid nitrogen freezing time and thawing temperature, and an influence rule of the moisture content in the coal rock samples and the number of liquid nitrogen freezing-thawing circulations in the liquid nitrogen freeze-thawing permeability improvement process of the coal rock mass.
- 6. The method for liquid nitrogen circulation freezing-thawing permeability improvement simulation test of a coal rock sample according to claim 5, wherein, in the testing process, the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber is controlled via combination of the pressurizing valve, the liquid nitrogen pressurizing tube, and the low-temperature pressure meter, and the controlling process is as follows: the pressurizing valve is opened first, so that the liquid nitrogen in the liquid nitrogen freezing-thawing test chamber enters into the liquid nitrogen pressurizing tube, which is a single-layer heat-conducting copper tube; the liquid nitrogen absorbs heat, expands quickly, and is vaporized into nitrogen gas in the liquid nitrogen pressurizing tube; the nitrogen gas enters into the liquid nitrogen freezing-thawing test chamber, the low-temperature pressure meter displays the pressure value and controls the open/close of the pressurizing valve, so as to control the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber; the liquid nitrogen expansion pressure in the liquid nitrogen freezing-thawing test chamber is applied to the coal rock sample via the liquid nitrogen, and that is the confining pressure exerted on the coal rock sample in the testing process.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510444636.X | 2015-07-24 | ||
| CN201510444636.XA CN105136837B (en) | 2015-07-24 | 2015-07-24 | Liquid nitrogen circulating freeze-thawing permeability-increasing simulation test system and method for coal rock sample |
| PCT/CN2015/099319 WO2017016168A1 (en) | 2015-07-24 | 2015-12-29 | Test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of coal rock sample |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2015403840A1 AU2015403840A1 (en) | 2017-03-16 |
| AU2015403840B2 true AU2015403840B2 (en) | 2017-11-23 |
Family
ID=54722263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2015403840A Ceased AU2015403840B2 (en) | 2015-07-24 | 2015-12-29 | Test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of coal rock sample |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN105136837B (en) |
| AU (1) | AU2015403840B2 (en) |
| WO (1) | WO2017016168A1 (en) |
Families Citing this family (43)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105136837B (en) * | 2015-07-24 | 2017-08-29 | 中国矿业大学 | Liquid nitrogen circulating freeze-thawing permeability-increasing simulation test system and method for coal rock sample |
| CN106645627A (en) * | 2016-09-21 | 2017-05-10 | 中国矿业大学(北京) | Strain measurement method for water-absorption free expansion of coal rocks |
| CN106840911B (en) * | 2017-01-05 | 2019-12-24 | 中国石油大学(华东) | A liquid nitrogen controlled temperature and pressure controlled freeze-thaw damage shale experimental device and method |
| CN106959246B (en) * | 2017-02-17 | 2019-06-18 | 中国石油大学(华东) | A liquid nitrogen anhydrous fracturing simulation experiment device |
| CN106680129B (en) * | 2017-02-24 | 2019-08-02 | 新华水力发电有限公司 | Rock sample recycles the simulation of dry and wet freezing-thawing and damage deterioration test device |
| CN106770418B (en) * | 2017-03-17 | 2018-02-23 | 西安科技大学 | The device and method that Rock And Soil internal moisture migrates in monitoring frozen-thaw process in real time |
| CN107091798B (en) * | 2017-04-21 | 2019-07-09 | 中国矿业大学 | Simulator is transformed in anxious formula hot and cold alternation coalbed methane reservoir |
| CN107543512B (en) * | 2017-08-21 | 2024-02-23 | 水利部交通运输部国家能源局南京水利科学研究院 | Concrete freezing and thawing volume deformation testing device |
| CN107476794B (en) * | 2017-09-28 | 2019-05-07 | 徐州工程学院 | Method for increasing coal gas permeability by injecting high-temperature nitrogen after liquid nitrogen gasification circulation |
| CN107764659B (en) * | 2017-11-24 | 2024-01-05 | 河南理工大学 | Coal rock mechanical testing device and method under low-temperature liquid nitrogen impact |
| CN108051477B (en) * | 2017-12-28 | 2020-08-21 | 核工业北京地质研究院 | A method for measuring lateral thermal conductivity of rock under uniaxial compression |
| CN108333053A (en) * | 2018-02-01 | 2018-07-27 | 石家庄铁道大学 | A kind of rock Frozen-thawed cycled equipment that can apply axial compressive force |
| CN108614089A (en) * | 2018-05-09 | 2018-10-02 | 重庆交通大学 | Compacted fill freeze thawing and weathering environmental simulation system and its test method |
| CN110501371A (en) * | 2018-05-16 | 2019-11-26 | 天津市惠达实验仪器有限公司 | A kind of energy-saving fast freeze-thaw test machine |
| CN108709815B (en) * | 2018-05-23 | 2021-03-23 | 中国石油大学(华东) | Experimental device and method for measuring fracture toughness of rock at low temperature |
| CN108761025A (en) * | 2018-05-29 | 2018-11-06 | 西安科技大学 | A kind of monitoring liquid nitrogen fracturing coal sample effect experiment device in real time |
| CN110726655A (en) * | 2018-07-16 | 2020-01-24 | 中国石油化工股份有限公司 | Experimental method for simulating shale organic pore evolution process |
| CN109630087B (en) * | 2019-01-15 | 2023-04-25 | 河南理工大学 | Pressurized liquid nitrogen leaching coal body fracturing anti-reflection device and anti-reflection experimental method |
| CN110331945B (en) * | 2019-03-27 | 2021-12-03 | 中国石油大学(华东) | Polar region drilling platform derrick heat preservation heating experimental device and experimental method |
| CN110485981B (en) * | 2019-09-10 | 2023-06-23 | 河南理工大学 | Pressurized liquid nitrogen and nitrogen coupling fracturing anti-reflection device and anti-reflection experimental method |
| CN110895210B (en) * | 2019-12-05 | 2025-03-18 | 国网辽宁省电力有限公司检修分公司 | A movable transformer cooling temperature sensing system detector |
| CN111551638B (en) * | 2020-05-06 | 2022-08-16 | 武汉科技大学 | Method for measuring freeze-thaw wave velocity and deformation of low-temperature saturated rock in real time |
| CN111983192B (en) * | 2020-08-25 | 2022-03-11 | 西南石油大学 | Quantitative determination method of massive escape depth of shale gas in syncline background |
| CN112255258B (en) * | 2020-09-24 | 2021-10-15 | 中国矿业大学 | A monitoring system and method for sample freeze-thaw cycle experiment |
| CN112684109B (en) | 2020-12-11 | 2022-02-01 | 西南石油大学 | High-temperature and high-pressure drilling fluid inhibition evaluation device and application method thereof |
| CN112285328B (en) * | 2020-12-15 | 2024-09-24 | 吉林大学 | A water-rock experimental device for simulating the formation process of mineral water quality in cold regions |
| CN112748146B (en) * | 2020-12-24 | 2023-09-19 | 黄河勘测规划设计研究院有限公司 | Freezing and thawing cycle experimental device capable of considering stress and water content coupling |
| CN112858017B (en) * | 2021-01-05 | 2024-04-05 | 西安科技大学 | Test device and test method for comprehensively simulating dynamic pressure-bearing soaking and freeze thawing environments |
| CN112946204B (en) * | 2021-03-17 | 2023-03-14 | 重庆大学 | Integrated pumping and gas injection system for simulating coal and gas outburst experiments |
| CN113156079B (en) * | 2021-03-31 | 2023-06-27 | 西安科技大学 | Experimental device for testing space-time evolution and mechanical parameters of liquid nitrogen immersed coal sample cracks |
| CN113433223B (en) * | 2021-06-23 | 2024-01-23 | 西安科技大学 | Acoustic emission monitoring experiment system for whole process of liquid nitrogen freeze thawing coal |
| CN113433292A (en) * | 2021-06-25 | 2021-09-24 | 中国矿业大学 | System and method for testing evolution of microstructure of discrete sample under freeze-thaw cycle action |
| CN113466286B (en) * | 2021-06-30 | 2023-04-14 | 中国科学院西北生态环境资源研究院 | Freeze-thaw test equipment for simulating the freezing-thawing process of concrete at ultra-low temperature and large temperature difference |
| CN113466434A (en) * | 2021-07-13 | 2021-10-01 | 中国科学院西北生态环境资源研究院 | Self-feeding frozen soil mechanical testing system |
| CN113567322B (en) * | 2021-07-27 | 2024-01-26 | 安徽理工大学 | A test device and method for studying the mechanical properties of porous media caused by water pressure |
| CN113984808B (en) * | 2021-10-28 | 2023-07-21 | 中国科学院西北生态环境资源研究院 | Test method for expanding rock fissures by freezing |
| CN113984807B (en) * | 2021-10-28 | 2023-07-21 | 中国科学院西北生态环境资源研究院 | Experimental method based on real-time expansion of rock fractures under freeze-thaw and fracturing |
| CN114964129B (en) * | 2022-04-14 | 2025-03-25 | 葛洲坝集团交通投资有限公司 | A dry-wet cycle confinement constraint expansion rate automatic acquisition test instrument and method |
| CN115600425B (en) * | 2022-11-07 | 2023-05-02 | 中国科学院武汉岩土力学研究所 | Shale compressibility evaluation device and method based on vermiculite thermal expansion fracturing |
| CN116359093A (en) * | 2023-03-31 | 2023-06-30 | 中国矿业大学(北京) | A quantification method of thermal fracture and anti-reflection effect of coal rock |
| CN116338146B (en) * | 2023-04-11 | 2025-08-15 | 桂林理工大学 | Temperature control type soil body water holding-shrinkage curve combined test device and method thereof |
| CN116399732A (en) * | 2023-06-08 | 2023-07-07 | 北京科技大学 | Visual test system and method for rapid auxiliary rock breaking through freezing and thawing cold and hot impact |
| CN118362341B (en) * | 2024-06-18 | 2024-08-27 | 山东智德汇新能源科技有限公司 | A stable rock sampling device for geological exploration |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104677778A (en) * | 2014-12-22 | 2015-06-03 | 中国石油大学(华东) | Device and method for evaluating temporarily freezing plugging properties of coalbed methane in process of fracturing |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU583319A1 (en) * | 1975-07-11 | 1977-12-05 | Карагандинский политехнический институт | Apparatus for simulating spontaneous coal outburst |
| JPH11183361A (en) * | 1997-12-22 | 1999-07-09 | Canon Inc | High-temperature and high-humidity test apparatus and its heating and humidifying method |
| US7052174B2 (en) * | 2004-09-16 | 2006-05-30 | The United States Of America As Represented By The Secretary Of The Army | Device for determining changes in dimension due to temperature fluctuation |
| CN101487835B (en) * | 2009-02-06 | 2013-06-05 | 煤炭科学研究总院重庆研究院 | Test apparatus for coal and gas burst |
| CN102507865B (en) * | 2011-10-21 | 2014-03-26 | 山东科技大学 | Simulation test system of coal-gas outburst during rock cross-cut coal uncovering |
| CN104297069A (en) * | 2014-10-21 | 2015-01-21 | 安徽理工大学 | Gas-containing coal hydrofracture-induced dynamic damage simulation monitoring device and method |
| CN104655806B (en) * | 2015-03-03 | 2016-04-06 | 河南理工大学 | A method and device for testing energy change and permeability of nitrogen-induced fracturing coal seams |
| CN104777269B (en) * | 2015-03-24 | 2016-08-31 | 中国矿业大学 | A Simulation Test Method of Supercritical CO2 Injection and Coalbed Methane Enhanced Displacement |
| CN104712302A (en) * | 2015-04-14 | 2015-06-17 | 新疆大学 | Cyclic freezing-melting anti-reflection method for low-permeability coal-bed gas reservoir |
| CN105136837B (en) * | 2015-07-24 | 2017-08-29 | 中国矿业大学 | Liquid nitrogen circulating freeze-thawing permeability-increasing simulation test system and method for coal rock sample |
-
2015
- 2015-07-24 CN CN201510444636.XA patent/CN105136837B/en active Active
- 2015-12-29 WO PCT/CN2015/099319 patent/WO2017016168A1/en not_active Ceased
- 2015-12-29 AU AU2015403840A patent/AU2015403840B2/en not_active Ceased
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104677778A (en) * | 2014-12-22 | 2015-06-03 | 中国石油大学(华东) | Device and method for evaluating temporarily freezing plugging properties of coalbed methane in process of fracturing |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2015403840A1 (en) | 2017-03-16 |
| WO2017016168A1 (en) | 2017-02-02 |
| CN105136837A (en) | 2015-12-09 |
| CN105136837B (en) | 2017-08-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU2015403840B2 (en) | Test system and method for liquid nitrogen circle freeze-thawing permeability-increasing simulation of coal rock sample | |
| Qin et al. | Advances in liquid nitrogen fracturing for unconventional oil and gas development: A review | |
| Fan et al. | Enhancing coalbed methane recovery with liquid CO2 fracturing in underground coal mine: From experiment to field application | |
| Zhai et al. | Pore structure in coal: pore evolution after cryogenic freezing with cyclic liquid nitrogen injection and its implication on coalbed methane extraction | |
| Eggertsson et al. | Improving fluid flow in geothermal reservoirs by thermal and mechanical stimulation: The case of Krafla volcano, Iceland | |
| Song et al. | Mechanical property of artificial methane hydrate under triaxial compression | |
| Wen et al. | Improving coal seam permeability and displacing methane by injecting liquid CO2: An experimental study | |
| Yin et al. | Permeability evolution and mesoscopic cracking behaviors of liquid nitrogen cryogenic freeze fracturing in low permeable and heterogeneous coal | |
| Liu et al. | Experimental measurements of mechanical properties of carbon dioxide hydrate-bearing sediments | |
| Li et al. | LCO2-ECBM technology for preventing coal and gas outburst: Integrated effect of permeability improvement and gas displacement | |
| Wang et al. | Temperature-pressure coupling effect on gas desorption characteristics in coal during low-variable temperature process | |
| Li et al. | Changes in pore structure and permeability of middle–high rank coal subjected to liquid nitrogen freeze–thaw | |
| Zagorščak et al. | Effects of subcritical and supercritical CO2 sorption on deformation and failure of high-rank coals | |
| CN106680129A (en) | Dry-wet-freeze-thaw cycle environment simulation and damage and deterioration test device and method for rock sample | |
| Wei et al. | Non-uniformity of coal damage caused by liquid nitrogen freeze-thaw | |
| CN106840911A (en) | A kind of liquid nitrogen temperature-control pressure-control freezing-thawing damage shale experimental provision and method | |
| Qin et al. | Liquid nitrogen’s effect on the mechanical properties of dried and water-saturated frozen coal | |
| Huang et al. | Hydraulic fracturing technology for improving permeability in gas-bearing coal seams in underground coal mines | |
| CN107741372A (en) | An experimental device for rock fracture under the cold impact of liquid nitrogen | |
| CN105606482A (en) | Method for testing accumulated damage effects of liquid nitrogen on fracture structures of water-containing coal samples | |
| CN112879074A (en) | Positive and negative pressure inert injection method and system for rapid fire prevention and extinguishing in goaf | |
| Sun et al. | Hole-bottom freezing technique based on phase change heat transfer for gas-hydrates sampling: Efficiency optimization of refrigeration change of phase | |
| CN106337694A (en) | Carbon dioxide pressure releasing and fire fighting technology and equipment for goafs | |
| Yang et al. | Experimental study on mechanical and permeability characteristics of rock-cement interface in ultra-low temperature environment | |
| Liangwei et al. | Variation law of roof stress and permeability enhancement effect of repeated hydraulic fracturing in low‐permeability coal seam |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGA | Letters patent sealed or granted (standard patent) | ||
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |