GEL-LIKE ENERGETIC MATERIAL AND PREPARATION METHOD THEREFOR

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims priority to Chinese patent application No. 202211273737.1, filed on Oct. 18, 2022, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure belongs to the field of novel explosives, and relates to a gel-like energetic material and a preparation method therefor.

BACKGROUND

An electrohydraulic effect refers to a complex physical process in which energy is rapidly converted and a variety of extreme physical effects occur after a high-voltage high current passes through a liquid medium, and resulting mechanical effects, acoustic effects, light effects, chemical effects and the like, have great prospects for application in industry. In particular, a water shock wave generation technology based on the electrohydraulic effect is widely applied in scenarios including machining and forming, electrical pulse cleaning, extracorporeal lithotripsy, oil-gas unplugging, reservoir transformation and the like. Water gap discharge is a common water shock wave generation technology based on the electrohydraulic effect. After a strong electric field is loaded to electrodes at two ends of a gap, a water medium between the electrodes undergoes electric breakdown and forms a plasma discharge channel. Energy is further injected to rapidly expand the discharge channel and push the external water medium to form a strong shock wave that propagates outward, which has advantages such as controllability, safety, and good repeatability. Compared to a water shock wave generation technology based on a metal wire electric explosion, the water gap discharge does not require supporting wire feeding equipment, and a water gap will automatically recover to a non-breakdown state after energy of a capacitor is released, so as to prepare for the next discharge. Therefore, the water gap discharge has more advantages in efficient repetitive work scenarios. However, both the water gap discharge and the metal wire electric explosion in water are limited by the low energy conversion efficiency of stored energy of a pulse capacitor. When a device volume is limited by complex and narrow working environments (underground, mines, tunnels, etc.), shock waves with sufficient energy cannot be generated.

Based on this background, in the research field of the metal wire electric explosion in water, people have proposed a load configuration in which an insensitive energetic material is wrapped around a metal wire. The insensitive energetic material on an outer layer is ignited by using the metal wire electric explosion, and a shock wave of the wire explosion is coupled with a shock wave of the energetic material to enhance shock wave energy generated by a single operation. The used energetic material often does not contain explosives in an entry of dangerous goods, and a common formula is a mixture containing nitromethane, aluminum powder, and metal oxides. However, this manner has the following defects: 1) it requires an ammunition feeding mechanism with a complex structure and the like to assist in completing repetitive works, and is expensive, and structures such as a rotating wheel and a bearing are prone to a failure under an action of the strong shock wave; 2) a liquid energetic material needs to be filled into a housing to form an energetic ammunition, but under strong impact, an energetic ammunition case in a storage compartment is prone to damage, affecting the repetitive works; and 3) viscosity of the liquid energetic material using a thickener such as cellulose acetate is insufficient, resulting in a sedimentation problem and inability to stand for more than 24 hours.

Therefore, the development of an energetic material that can be used for the water gap discharge is a key issue that urgently needs to be addressed, so as to achieve reliable generation of a single strong shock wave in complex and narrow operating terrains. In addition, the following key issues further need to be addressed: 1) an insensitive energetic material having a self-supporting property and being insoluble in water is developed, and can be stably maintained in a water gap for a long time without a housing; 2) a continuous working device that can push the energetic material to the water gap is developed and is suitable for an existing water gap discharge device, a structure is simple and reliable, and the energetic material in a storage compartment is stored stably for a long time without decomposition, failure, or sympathetic detonation; and 3) a supporting device for preparing the energetic material is developed and can prepare a uniform, impurity-free, and bubble-free energetic material.

SUMMARY

An objective of the present disclosure is to solve problems in the prior art and provide a gel-like energetic material and a preparation method therefor.

In a first aspect, the present disclosure provides a gel-like energetic material, including, in parts by mass, 30-65 parts of nitromethane, 10-30 parts of metal oxide powder, 15-40 parts of aluminum powder and 1-3 parts of hydrophobic fumed silica for gelation.

In a second aspect, the present disclosure provides a method for preparing a gel-like energetic material, including the following steps:

• • step 1: mixing metal oxide powder and aluminum powder uniformly to obtain aluminum powder/metal oxide powder;
  • step 2: adding the aluminum powder/metal oxide powder into nitromethane, and stirring at a room temperature to uniformly mix the nitromethane with the aluminum powder/metal oxide powder, so as to obtain aluminum powder/metal oxide/nitromethane powder; and
  • step 3: adding hydrophobic fumed silica into the aluminum powder/metal oxide/nitromethane powder, and stirring at a room temperature to make a mixture be gelated, so as to obtain the gel-like energetic material; wherein
  • in step 2 and step 3, a revolution speed for stirring is in a range from 50 r/min to 500 r/min.

In a third aspect, the present disclosure provides a method for preparing a gel-like energetic material, the method is based on a device for preparing the gel-like energetic material, and the device includes a cavity, a cavity sealing cover, a spiral stirring rod and a stirring extension rod;

• • the cavity is provided with the cavity sealing cover, the spiral stirring rod is arranged in the cavity, and a stirring rod installation hole is formed at a bottom of the cavity;
  • the cavity sealing cover is provided with a pressurization valve;
  • an installation seat is arranged at a bottom of the spiral stirring rod, the installation seat is arranged in the stirring rod installation hole, a filling port communicating with the cavity is formed in the installation seat, and an outlet of the filling port is provided with a counter bore for connecting the stirring extension rod; and
  • a tail end of the stirring extension rod is connected to a stirring motor for driving the spiral stirring rod to rotate; and
  • the method includes the following steps:
  • step 1: mixing metal oxide powder and aluminum powder uniformly to obtain aluminum powder/metal oxide powder;
  • step 2: adding nitromethane into the cavity, then adding the aluminum powder/metal oxide powder to the cavity, covering the cavity sealing cover, starting the stirring motor to drive the spiral stirring rod to perform rotary stirring at a room temperature so as to uniformly mix the nitromethane and the aluminum powder/metal oxide powder, and turning off the stirring motor; and
  • step 3: opening the cavity sealing cover, adding hydrophobic fumed silica into the cavity, covering the cavity sealing cover, starting the stirring motor to drive the spiral stirring rod to perform rotary stirring at a room temperature so as to make a mixture be gelated, and obtaining the gel-like energetic material.

Compared with the prior art, the present disclosure has the following beneficial effects:

• • the gel-like energetic material of the present disclosure uses a hydrophobic silica additive to enable it to achieve self-supporting in water. When mass is 10 g, a conical energetic material block with a height of more than 5 cm and a retention time of more than 10 min is formed, can be stably filled in a water gap for a long time without a housing and enables positive and negative electrodes of the gap to communicate with each other. Other compositions of the energetic material do not contain explosives in an entry of dangerous goods, and a common formula is a mixture containing nitromethane, aluminum powder, and metal oxides. After initiating explosive device testing, friction sensitivity and impact sensitivity are both zero, and safety is extremely high. Formula compositions are insoluble or extremely difficult to dissolve in water, will not fail or decompose after soaked in water for a long time, and can still detonate normally under an action of a pulse current. After being filled in the water gap, the gel-like energetic material can generate a shock wave with a fixed amplitude, impulse and energy under drive of a pulse source with specific parameters, and meanwhile has excellent repeatability. Compared with water gap discharge under original parameters, the amplitude, impulse, and energy of the shock wave are greatly improved, which has great engineering application prospects.

The method for preparing the gel-like energetic material of the present disclosure can be based on the device for preparing the gel-like energetic material, and the used spiral stirring rod can quickly mix powder compositions (the aluminum powder and the metal oxide powder), a liquid composition (the nitromethane) and a gel additive (the hydrophobic fumed SiO₂), so as to prepare the uniform, impurity-free and bubble-free gel-like energetic material in a short time. The preparation device adopts a sealed structure, which solves a problem of volatilization of the nitromethane during a preparation process and eliminates impurities from mixing into the energetic material during a stirring preparation process. A proportion of the compositions of the gel-like energetic material directly affects a detonation effect. After preparation, the gel-like energetic material is directly filled to a continuous pushing working device through the preparation device, reducing a loss in a process of preparation, sub-packaging and filling, and realizing an accurate proportion of the energetic material.

BRIEF DESCRIPTION OF DRAWINGS

In order to illustrate technical solutions of embodiments of the present disclosure more clearly, accompanying drawings needing to be used in the embodiments will be introduced below briefly. It should be understood that the accompanying drawings below only show some embodiments of the present disclosure, and thus should not be regarded as limitation on the scope. Those ordinarily skilled in the art can further obtain other related accompanying drawings according to these accompanying drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a device for preparing a gel-like energetic material of the present disclosure.

FIG. 2 is a schematic structural diagram of a continuous pushing device of a gel-like energetic material of the present disclosure.

FIG. 3 is a schematic structural diagram of a gap discharge device of the present disclosure.

FIG. 4 is a schematic structural diagram of a water gap discharge experimental system of the present disclosure.

FIG. 5 is a discharge oscillogram of Embodiment 1.

FIG. 6 is a discharge oscillogram of Embodiment 4.

FIG. 7 is an oscillogram of a shock wave pressure of Embodiment 1.

FIG. 8 is an oscillogram of a shock wave pressure of Embodiment 2.

FIG. 9 is an oscillogram of a shock wave pressure of Embodiment 3.

FIG. 10 is an oscillogram of a shock wave pressure of Embodiment 4.

FIG. 11 is an oscillogram of a shock wave pressure of Comparative Example 1.

FIG. 12 is an oscillogram of a shock wave pressure of Comparative Example 2.

FIG. 13 is an oscillogram of a shock wave pressure of Comparative Example 3.

FIG. 14 is a schematic diagram of a rock breaking system of the present disclosure.

FIG. 15 is a flow diagram of a rock breaking method of the present disclosure.

FIG. 16 is a schematic diagram of a shale reservoir transformation system of a vertical well of the present disclosure.

FIG. 17 is a schematic diagram of a shale reservoir transformation system of a horizontal well of the present disclosure.

FIG. 18 is a flow diagram of a shale oil reservoir transformation method of the present disclosure.

Wherein, 1—Device for preparing gel-like energetic material, 2—Continuous pushing device of gel-like energetic material, 3—Water gap discharge experimental platform, 4—Integrated gap discharge pulse source, 101—Pressurization valve, 102—Spiral stirring rod, 103—Cavity sealing cover, 104—Cavity, 105—Stirring rod installation hole, 106—Filling port, 107—Stirring extension rod, 201—Battery, 202—Control module, 203—Sealed adapter socket, 204—Motor control line, 205—Motor power line, 206—Motor, 207—Silicone oil, 208—Ball screw, 209—Silicone oil partition plate, 210—Screw rod, 211—Pressure relief hole, 212—Sealing ring, 213—Push piston block, 214—energetic material storage compartment, 215—Assembly thread, 216—Energetic material pushing port, 217—Gel-like energetic material, 218—Conical energetic material block, 301—Large capacitor, 302—Three-electrode switch, 303—Current probe, 304—Coaxial cable, 305—Voltage probe, 306—Coaxial transmission device, 307—Shock wave, 308—Shock wave pressure probe, 309—Forming plate, 310—Water tank, 311—Oscilloscope, 401—Reflux column, 402—High-voltage electrode, 403—Electrode insulator, 404—High-voltage transmission rod, 405—Gas switch, 406—Small capacitor, 407—Charging insulator, 408—Cable socket, 409—Portable coaxial cable, 501—Target rock mass, 502—Hole, 503—Portable power supply, 601—Control platform, 602—Vertical well, 603—Transmission coaxial cable, 604—Complex fracture network, 605—Pumping unit, 606—Heating well, 607—Coiled tubing, 608—Oil production well, 609—Low-permeability shale oil, and 610—Horizontal well.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In order to make objectives, technical solutions and advantages of embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described below clearly and completely with reference to accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are part of the embodiments of the present disclosure, but not all the embodiments. The components of the embodiments of the present disclosure, which are generally described and shown in accompanying drawings here, may be arranged and designed in various different configurations.

Therefore, the following detailed description of the embodiments of the present disclosure provided in the accompanying drawings is not intended to limit the claimed scope of protection of the present disclosure, but merely represents selected embodiments of the present disclosure. On the basis of the embodiments in the present disclosure, all other embodiments obtained by those ordinarily skilled in the art without creative efforts fall within the scope of protection of the present disclosure.

It should be noted that similar numerals and letters represent like items in the following accompanying drawings, therefore, once an item is defined in one accompanying drawing, it does not require further definition and explanation in the subsequent accompanying drawings.

In the descriptions of the embodiments of the present disclosure, it should be noted that an orientation or a position relationship indicated by terms “upper”, “lower”, “horizontal”, “inner” and the like is an orientation or a position relationship shown on the basis of the accompanying drawings, or an orientation or a position relationship of a product of the present disclosure which is conventionally placed in use, is only to facilitate description of the present disclosure and simplify the description, rather than indicating or implying that the indicated device or element must have a specific orientation or be constructed and operated in the specific orientation, and therefore cannot be understood as limitation to the present disclosure. In addition, terms “first”, “second” and the like are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

Furthermore, if a term “horizontal” is present, it does not mean that the component is required to be absolutely horizontal, but can be slightly tilted. For example, “horizontal” only refers to its direction being more horizontal relative to “vertical”, and does not mean that the structure must be completely horizontal, but can be slightly tilted.

In the descriptions of the embodiments of the present disclosure, it should further be noted that unless otherwise expressly stated and limited, the terms “arrange”, “install”, “connect” and “link” should be understood in a broad sense, for example, they may be a fixed connection, or a detachable connection, or an integrated connection; may be a mechanical connection, or an electrical connection; and may be a direct connection, or an indirect connection through an intermediate medium, or internal communication of two elements. Those ordinarily skilled in the art may understand the specific meaning of the above terms in the present disclosure according to the specific situation.

The present disclosure is further described in detail below with reference to the accompanying drawings:

• • an embodiment of the present disclosure discloses a self-supporting gel-like energetic material, which can be stably filled in a gap for a long time without a housing, and includes, in parts by mass, 30-40 parts of nitromethane, 10-30 parts of metal oxide powder, 20-60 parts of aluminum powder and 1-2 parts of hydrophobic fumed silica for gelation. Types of the metal oxide powder include, but are not limited to copper oxide, manganese dioxide, ferric oxide or ferroferric oxide. A particle size of the metal oxide powder is in a range from 1 μm to 100 μm, and a particle size of the aluminum powder is in a range from 1 μm to 100 μm.

An embodiment of the present disclosure discloses a method for preparing the gel-like energetic material above, including the following steps:

• • step 1: metal oxide powder and aluminum powder are mixed uniformly to obtain aluminum powder/metal oxide powder;
  • step 2: the aluminum powder/metal oxide powder is added into nitromethane, and stirred at a revolution speed ranging from 50 r/min to 500 r/min at a room temperature to uniformly mix the nitromethane with the aluminum powder/metal oxide powder, so as to obtain aluminum powder/metal oxide/nitromethane powder; and
  • step 3: hydrophobic fumed silica is added into the aluminum powder/metal oxide/nitromethane powder, and stirred at a revolution speed ranging from 50 r/min to 500 r/min at a room temperature to make a mixture be gelated, so as to obtain the gel-like energetic material.

As shown in FIG. 1, an embodiment of the present disclosure discloses a device 1 for preparing the gel-like energetic material for implementing the above method for preparing the gel-like energetic material, and the device includes a cavity 104, a cavity sealing cover 103, a spiral stirring rod 102 and a stirring extension rod 107. The cavity 104 is provided with the cavity sealing cover 103, the spiral stirring rod 102 is arranged in the cavity, and a stirring rod installation hole 105 is formed at a bottom of the cavity; the cavity sealing cover 103 is provided with a pressurization valve 101; an installation seat is arranged at a bottom of the spiral stirring rod 102, the installation seat is arranged in the stirring rod installation hole 105, a filling port 106 communicating with the cavity 104 is formed in the installation seat, and an outlet of the filling port 106 is provided with a counter bore for connecting the stirring extension rod 107; and a tail end of the stirring extension rod 107 is connected to a stirring motor for driving the spiral stirring rod 102 to rotate.

Raw materials for preparing the gel-like energetic material are placed in the cavity 104, and the spiral stirring rod 102 is installed in the cavity through the stirring rod installation hole 105, so that all the raw materials are uniformly mixed and gelated. One end of the stirring extension rod 107 is connected to the spiral stirring rod 102, and the other end of the stirring extension rod may be connected to the stirring motor for low-speed stirring or may also perform manual stirring. Due to the volatility of the nitromethane, the cavity sealing cover 103 is used to seal the entire cavity 104 and its interior during the entire stirring process. After the gel-like energetic material is prepared, the stirring extension rod 107 is removed to expose the internally-hollow filling port 106, the interior of the cavity 104 is pressurized through the pressurization valve 101, and the energetic material is extruded from the filling port 106 for sub-packaging, so as to achieve the accurate proportion of the energetic material.

Embodiment 1

• • this embodiment discloses a gel-like energetic material, including, in parts by mass, 40.375 parts of nitromethane, 23 parts of copper oxide powder, 34.5 parts of aluminum powder and 1-2 parts of hydrophobic fumed silica for gelation.

This embodiment further discloses a method for preparing a gel-like energetic material, including the following steps:

• • step 101: 23 parts of copper oxide powder and 34.5 parts of aluminum powder are placed in a three-dimensional mixer to mix for 30 minutes to be completely and uniformly mixed, wherein a particle size of the copper oxide powder is in a range from 1 μm to 100 μm, and a particle size of the aluminum powder is in a range from 1 μm to 100 μm;
  • step 102: a spiral stirring rod 102 is installed on a cavity 104 of a device 1 for preparing the gel-like energetic material, 40.375 parts of nitromethane is taken and placed in the cavity 104, then 20 g of fully mixed aluminum powder/copper oxide powder is placed in the cavity 104, a cavity sealing cover 103 is covered, and the spiral stirring rod 102 performs low-speed rotary stirring at a room temperature for 10 minutes to uniformly mix the nitromethane and the mixed powder, wherein purity of the nitromethane is greater than 99%, the room temperature ranges from 10° C. to 30° C., and low-speed rotary stirring is in a range from 50 r/min to 500 r/min;
  • step 103: the cavity sealing cover 103 is opened, 2.125 parts of hydrophobic fumed silica is taken and placed in the cavity 104, the cavity sealing cover 103 is covered, and the spiral stirring rod 102 performs low-speed rotary stirring at a room temperature for 10 minutes so as to make the energetic material be gelated;
  • step 104: a pressurization valve 101 on the cavity sealing cover 103 is opened, a filling port 106 below the spiral stirring rod 102 is opened, and pressurization is performed to fill the gel-like energetic material into an energetic material storage compartment 214 of a continuous pushing device 2 of the gel-like energetic material; and
  • step 105: the energetic material storage compartment 214 of the continuous pushing device 2 of the gel-like energetic material is installed to the continuous pushing device 2 of the gel-like energetic material.

TABLE 1
Embodiments 2-4, Comparative Examples 1-3

Parameters of gel-like energetic material

Copper

	oxide	Aluminum	Nitro-	Fumed	Electrode gap	Total
Name	powder	powder	methane	SiO2	distance/mm	mass

Embodiment 2	20	parts	30	parts	47.5	parts	2.5	parts	20	3.2	g
Embodiment 3	17	parts	25.5	parts	54.625	parts	2.875	parts	20	3.2	g
Embodiment 4	13	parts	19.5	parts	64.125	parts	3.375	parts	20	3.2	g
Comparative	0	parts	0	parts	0	parts	0	parts	20	0	g
Example 1
Comparative	17	parts	25.5	parts	54.625	parts	0	parts	20	3.2	g
Example 2
Comparative	17	parts	25.5	parts	54.625	parts	2.875	parts	10	1.6	g
Example 3

The difference between Comparative Example 1 and Embodiments 1-4 is that the continuous pushing working device is not started by pre-discharge, a water gap formed between a pushing port of the energetic material and a high-voltage electrode is still in a length of 20 mm, and a gel-like energetic material block is not contained.

The difference between Comparative Example 2 and Embodiment 3 is that hydrophobic fumed SiO₂ is not added to make the energetic material be gelated.

The difference between Comparative Example 3 and Embodiment 3 is that mass of the conical gel-like energetic material block is 1.6 g, and an electrode gap distance is adjusted to be 10 mm.

FIG. 5 shows a discharge oscillogram of Embodiment 1. It can be seen that after a three-electrode switch is triggered, a discharge circuit is formed, and a high voltage is rapidly loaded onto a high-voltage electrode. Within a time period of 0 μs to 2.5 μs, the energetic material undergoes a breakdown process, with the voltage dropping from 7.5 kV to 3 kV and the current rapidly increasing from 0 kA to 30 kA. During this time period, a deposition rate of energy inside the energetic material is slow, and detonation has not yet begun. Within a time period of 2.5 μs to 10 μs, the interior of the energetic material undergoes complete breakdown, forming a plasma discharge channel. On the one hand, stored energy in a capacitor rapidly deposits inside the energetic material, causing a temperature of the energetic material in the breakdown channel to rise rapidly. On the other hand, temperature rise leads to an intense thermit reaction between the copper oxide powder and the aluminum powder in the gel energetic material, further increasing the temperature of the energetic material. The combined effect of the two causes the nitromethane to undergo detonation, producing a shock wave with extremely high amplitude, impulse, and energy. The detonation of the energetic material simultaneously constrains outward expansion of the plasma channel, resulting in a higher resistance value of the plasma channel and maintaining higher energy deposition power. Within a time period of 10 μs to 40 μs, a stable discharge channel is formed inside the energetic material, and voltage and current waveforms exhibit synchronous oscillation attenuation until they reach zero. In this process, the capacitor still continues to deposit the energy into the discharge channel of the energetic material, so as to maintain further development of a detonation wave in the gel-like energetic material until the 1200 J stored energy in the capacitor is released completely.

FIG. 6 is a discharge oscillogram of Embodiment 4. Compared to Embodiment 1, a proportion of doped aluminum powder and copper oxide is lower, which results in a higher resistance of the conical energetic material block formed. Therefore, after the electrode switch is triggered, the high voltage is loaded onto the high-voltage electrode, and a capacitor voltage of 20 kV is maintained within a time period of 0 μs to 2.5 μs. Within a time period of 2.5 μs to 5 μs, the energetic material undergoes the breakdown process, with the voltage dropping from 20 kV to 3 kV and the current rapidly increasing from 0 kA to 27 kA. During this time period, a deposition rate of energy inside the energetic material is slower, and detonation has not yet begun. Within a time period of 5 μs to 12 μs, the interior of the energetic material undergoes complete breakdown, forming a plasma discharge channel to cause the energetic material to undergo detonation. Comparing discharge processes of Embodiments 1 and 4, it can be seen that the doping of the aluminum powder and the copper oxide powder will affect formation of breakdown and discharge channels, and affect subsequent energy deposition efficiency. The aluminum powder plays a decisive role in this process, this is because the aluminum powder itself has lower resistance compared to the nitromethane, the copper oxide powder, and water, which is conducive to the formation of the breakdown and the discharge channels. The higher the content of the aluminum powder, the shorter the breakdown time of the energetic material, the higher the peak current, and the higher the energy deposition efficiency, which is also more conducive to the detonation of the energetic material. Therefore, a certain amount of the aluminum powder and the copper oxide powder in parts must be doped in the gel-like energetic material, so that the nitromethane is detonated.

Referring to Table 2, experimental testing was performed on the gel-like energetic material under various proportions based on an above water gap discharge experimental platform, stored energy of a driving source was all 1200 J, and final experimental results were obtained.

TABLE 2
Experimental results of the gel-like energetic
material under various proportions

	Stored energy	Peak value	Impulse	Energy
	of driving	of shock	density/	density/
Name	source/J	wave/MPa	Pa · s	J · m−2

Embodiment 1	1200	10.1	529.7	1751.7
Embodiment 2	1200	11.2	503	1710.8
Embodiment 3	1200	11.5	566.9	2180.1
Embodiment 4	1200	6.5	257.4	478.9
Comparative	1200	6.5	74.5	69.1
Example 1
Comparative	1200	6.5	155.5	117.4
Example 2
Comparative	1200	6.8	337.6	799.3
Example 3

Referring to FIG. 7 to FIG. 10, it can be seen from Embodiments 1 to 4 that the gel-like energetic material can detonate under 1200 J of the stored energy of the driving source, so as to generate the shock wave with extremely high amplitude and impulse, which has certain engineering application value. The principle is that a pulse source injects a large amount of energy into the gap of the energetic material in a short period of time, causing the energetic material to break down and form a discharge channel. In addition, a metal oxide and the aluminum powder release a large amount of heat due to an intense thermit reaction. A synergistic effect of the two causes the gel-like energetic material to explode. On the one hand, a detonation wave propagates outwards to detonate the energetic material on an outer layer and enhance the shock wave, on the other hand, the detonation wave limits the expansion of the discharge channel inward to maintain a high resistance to accelerate deposition power of electric energy and maintain the propagation and development of the detonation wave.

Comparing Embodiments 1 to 4, it can be seen that peak values of the shock wave, impulse density and energy density generated by detonation of the gel-like energetic material under different proportions are different. The shock wave generated in Embodiment 3 is the strongest, as its proportion is most suitable for the formation and development of the detonation wave. When the proportion of the nitromethane in the gel-like energetic material is too high, the resistance of the formed conical energetic material block is too high, and the formation of the breakdown and the discharge channels is more difficult, which makes the deposition power of the electric energy be lower, which is not conducive to initiation and the propagation and development of the detonation wave. While when the proportion of the nitromethane in the gel-like energetic material is too low, although the conical energetic material block is easy to detonate, the content of the nitromethane in the propagation process of the detonation wave is too low, which is not conducive to further development. Therefore, the proportion has a regulating effect on the shock wave generated by the final explosion of the gel-like energetic material. In practical engineering, the formula of the gel-like energetic material can be adjusted as required to obtain an ideal peak value of the shock wave, impulse density and energy density.

Referring to FIG. 9 and FIG. 11, shock wave waveforms of Embodiment 3 and Comparative Example 1 are compared. A peak pressure of the shock wave in Embodiment 3 is 11.5 MPa, impulse density is 566.9 Pa·s, and energy density is 2180.1 J/m². A peak pressure of the shock wave in Comparative Example 1 is 6.5 MPa, impulse density is 74.5 Pa·s, and energy density is 69 J/m². The results show that the conical gel energetic material block with mass of 3.2 g and a height of 20 mm can increase the peak pressure of the shock wave by 1.8 times, the impulse density by 7.6 times, and the energy density by 31.6 times. Therefore, the continuous pushing device loaded with the gel-like energetic material can significantly improve the amplitude, energy density and impulse density of a single shock wave, and can reliably and continuously generate the shock wave.

Referring to FIG. 9 and FIG. 12, shock wave waveforms of Embodiment 3 and Comparative Example 2 are compared. A peak pressure of the shock wave in Embodiment 3 is 11.5 MPa, impulse density is 566.9 Pa·s, and energy density is 2180.1 J/m². A peak pressure of the shock wave in Comparative Example 2 is 6.5 MPa, impulse density is 155.5 Pa·s, and energy density is 117.4 J/m². The results show that the non-gelated energetic material can hardly enhance the shock wave of the water gap discharge. Because the non-gelated energetic material has no self-supporting effect and is still in a fluid state, it is impossible to maintain detonation within the electrode gap without a housing, and thus the generated shock wave is similar to that of the water gap discharge. The results are also similar for a solid-liquid composite energetic material doped with other thickening agents, such as cellulose acetate, because in these cases, the energetic material cannot be gelated to form a self-supporting property.

Referring to FIG. 9 and FIG. 13, shock wave waveforms of Embodiment 3 and Comparative Example 3 are compared. A peak pressure of the shock wave in Embodiment 3 is 11.5 MPa, impulse density is 566.9 Pa·s, and energy density is 2180.1 J/m². A peak pressure of the shock wave in Comparative Example 3 is 6.8 MPa, impulse density is 337.6 Pa·s, and energy density is 799.3 J/m². The results show that the larger the mass of the energetic material block pushed by the continuous pushing device in a single push, the stronger the shock wave generated. When the mass is 10 g, the gel-like energetic material can form a conical energetic material block with a height of more than 5 cm and a retention time in water of more than 10 min. In practical engineering, the mass of the gel-like energetic material and the gap distance can be adjusted as required to obtain an ideal peak value of the shock wave, impulse density and energy density.

In conclusion, the gel-like energetic material and its continuous pushing device of the present disclosure have the following several advantages:

1. the peak pressure of the single shock wave, impulse density, and energy density of the water gap discharge are significantly improved, and all modified integrated gap discharge pulse sources 4 are compatible.

2. The gel-like energetic material has a self-supporting effect, can be directly pushed into the water gap without the housing, does not fail or decompose after being soaked for a long time, and can still detonate normally under the action of the pulse current. At the same time, the non-housing structure significantly reduces costs during manufacturing, transportation and use processes, and improves the reliability of the device.

3. The continuous pushing device is simple and reliable in structure, and high in integration, and the energetic material in the storage compartment is stored stably for a long time without decomposition, failure, or sympathetic detonation.

4. The formula and filling mass of the gel-like energetic material have the regulating effect on the shock wave, and can be adjusted in practical engineering as required to obtain an ideal peak value of the shock wave, impulse density and energy density.

As shown in FIG. 2, an embodiment of the present disclosure discloses a continuous pushing device 2 of a gel-like energetic material, including a housing, and the housing is of a cylinder structure assembled by a front housing, a middle housing and a rear housing; and

an interior of the front housing is an energetic material storage compartment 214, an energetic material pushing port 216 communicating with the energetic material storage compartment 214 is formed in a front end of the front housing, and an adapter socket is arranged at a rear end of the front housing; the energetic material storage compartment 214 is filled with the gel-like energetic material 217; a motor 206 is arranged in the middle housing, an adapter socket is arranged at a front end of the middle housing, a sealed adapter socket 203 is arranged at a rear end of the middle housing, and the adapter socket at the front end is used to be connected with the adapter socket at the rear end of the front housing; the motor 206 is installed on a screw rod 210; a push piston block 213 is installed at a front end of the screw rod 210, and the push piston block 213 is sleeved with a sealing ring 212; a silicone oil partition plate 209 and a ball screw 208 are fixedly arranged between the push piston block 213 and the motor 206, and the ball screw 208 is located between the motor 206 and the silicone oil partition plate 209; in the middle housing, silicone oil 207 is filled between the silicone oil partition plate 209 and the sealed adapter socket 203 at the rear end of the middle housing; the rear housing is internally provided with a battery 201 and a control module 202, a sealed adapter socket 203 is arranged at a front end of the rear housing for sealing connection with the sealed adapter socket 203 at the rear end of the middle housing, and a rear end of the rear housing is of a closed structure; the control module 202 is installed on the battery 201 and connected to a control end of the motor 206; the battery 201 is connected to a power end of the motor 206; and the motor 206 drives the push piston block 213 to push the gel-like energetic material 217 out of the energetic material pushing port 216 to form a conical energetic material block 218.

The gel-like energetic material is stored in the energetic material storage compartment 214. Under the action of the push piston block 213, the gel-like energetic material is pushed out of the energetic material pushing port 216 to form the conical energetic material block 218. The push piston block 213 is pushed forward by the screw rod 210, and is sealed with the outside by installing the annular sealing ring 212. The motor 206 is connected to the other end of the screw rod 210 and provides propulsion power. The entire motor 206 is soaked in the silicone oil 207 to maintain insulation, and is sealed with the silicone oil partition plate 209 through the ball screw 208. A plurality of pressure relief holes 211 are formed between the silicone oil partition plate 209 and the push piston block 213 during the propulsion process to maintain a consistent water pressure inside and outside the device. The motor 206 is powered by the battery 201 and controlled by the control module 202. After passing through the sealed adapter socket 203, the motor is connected to a motor power line 205 through a motor control line 204. A Hall sensor, a vibration sensor and the like are installed in the control module 202 and can collect a current signal, a magnetic field signal, a vibration signal, etc. to control the motor 206 to work. An assembly thread 215 can install the continuous pushing device 2 of the gel-like energetic material on a modified integrated gap discharge pulse source 4, so as to improve an amplitude, impulse and energy of a shock wave.

A working principle of the continuous pushing device 2 of the gel-like energetic material of the present disclosure is as follows:

• • the continuous pushing device 2 of the gel-like energetic material can be installed on all the modified integrated gap discharge pulse sources 4 as an important supplement to the shock wave energy. Generally speaking, the continuous pushing device 2 of the gel-like energetic material is installed on one side of a ground electrode, and the energetic material pushing port 216 replaces a ground electrode of an original water gap discharge device, and forms a water gap with its high-voltage electrode. At the beginning of working, a pre-discharge manner can be used to enable the control module 202 to pick up the magnetic field signal and start the motor 206 to work, or an energetic material can be pre-set between the gaps. After the motor 206 works, the push piston block 213 is pushed through the screw rod 210 to extrude the gel-like energetic material 217 in the energetic material storage compartment 214, and the gel-like energetic material 217 will be extruded from the energetic material pushing port 216 to form the conical energetic material block 218 between the water gaps. After an operator controls an external power supply to charge a capacitor, a three-electrode switch is triggered to form a discharge circuit, and electrical energy is quickly injected into the conical energetic material block 218. Electric breakdown occurs inside the conical energetic material block 218 and a plasma discharge channel is formed. The resulting high temperature, radiation, and other effects cause the conical energetic material block 218 to detonate, and push a water medium to form the shock wave. During the discharge process, the control module 202 picks up the magnetic field signal and the vibration signal again, and starts the motor 206 to push the gel-like energetic material 217. The conical energetic material block 218 can be formed between the gaps again, which prepares for the next discharge and forms continuous working conditions. The energetic material pushing port 216 can be designed to be porous, Tesla valve and other forms to prevent propagation of explosion from igniting the gel-like energetic material 217 in the energetic material storage compartment 214. Moreover, since the energetic material storage compartment 214 is installed at one side of the ground electrode, a current directly forms a circuit through the energetic material pushing port 216 without passing through the overall structure, so the gel-like energetic material 217 in the energetic material storage compartment 214 has no risk of sympathetic detonation. However, when the continuous pushing device 2 of the gel-like energetic material is immersed in water for a long time, nitromethane at the energetic material pushing port 216 will gradually dissolve in the water, leaving hydrophobic fumed silica to form a hydrophobic protective layer, so that the gel-like energetic material 217 in the energetic material pushing port 216 can be stored for more than a month without failure and decomposition, and still be able to detonate stably.

The continuous pushing device of the gel-like energetic material of the present disclosure is applicable to all modified water gap discharge devices, and can be directly installed on one side of the ground electrode as a part of a reflux device. The energetic material is stored inside the pushing device and is pushed to a position between water gap electrodes by a linear motor through a piston structure. After detonation, the amplitude, impulse, and energy of the shock wave are greatly increased. The gel-like energetic material can be self-supporting and waterproof, and can be directly stored in the pushing device without filling an ammunition case and other materials. The pushing device is simple and reliable in structure and high in integration. Since the energetic material is not externally filled with the ammunition case, the shock wave will not cause leakage, sympathetic detonation or other problems to the energetic material to affect the repeated working of the device. The housing of the continuous pushing device is integrally designed and is stably connected to the ground electrode. During detonation, a high current flows directly into the ground through the housing without passing through the stored energetic material, eliminating a risk of electrostatic detonation. The overall sealing design of the device allows the energetic material to be stored inside for more than a month without failure, decomposition, or detonation, and to be able to still detonate stably.

As shown in FIG. 3, an embodiment of the present disclosure discloses a gap discharge device, including an integrated gap discharge pulse source 4 and a continuous pushing device 2 of a gel-like energetic material; and

• • the integrated gap discharge pulse source 4 includes a housing with an opening in a rear end, a small capacitor 406 is arranged inside a front end of the housing, a charging insulator 407 is arranged between the small capacitor 406 and a cable socket 408, and the cable socket 408 is formed in the charging insulator 407 for connecting the small capacitor 406 with an external cable; a gas switch 405 is arranged at a rear end of the small capacitor 406, one end of the gas switch 405 is connected to the small capacitor 406, the other end is connected to a high-voltage transmission rod 404, an outer side of the high-voltage transmission rod 404 is sleeved with an electrode insulator 403, and a high-voltage electrode 402 is arranged at a tail end of the high-voltage transmission rod 404; a reflux column 401 is arranged at a rear end of the housing, the reflux column 401 is in sealed connection with a front housing of the continuous pushing device 2, a detonation gap is formed between the reflux column and the front housing of the continuous pushing device, and the high-voltage electrode 402 is located in the detonation gap; and an energetic material pushing port 216 of the continuous pushing device 2 communicates with the detonation gap, and the continuous pushing device 2 pushes the gel-like energetic material 217 to the detonation gap, so as to form a conical energetic material block 218.

The gap discharge device of the present disclosure can be applied to outdoor working environments, including a mine, an oil well, a tunnel, etc. The gap discharge device highly integrates the gas switch 405 and the small capacitor 406. The small capacitor 406 is charged through a portable coaxial cable 409 via the cable socket 408, and electrical energy is transmitted to a water gap through the high-voltage transmission rod 404 and the high-voltage electrode 402. Then, a circuit is formed through the reflux column 401, and the electrode insulator 403 and the charging insulator 407 are used for internal insulation. During use, the continuous pushing device is installed on one side of the reflux column 401, and its energetic material pushing port 216 forms the water gap with the high-voltage electrode 402.

As shown in FIG. 4, an embodiment of the present disclosure discloses a water gap discharge experimental system, including a water gap discharge experimental platform 3 and the above gap discharge device;

• • the water gap discharge experimental platform 3 includes a water tank 310, a large capacitor 301, and an oscilloscope 311; the gap discharge device is vertically arranged in the water tank 310, and a coaxial transmission device 306 is installed at a front end of the gap discharge device; and a rear end of the coaxial transmission device 306 is connected to the front end of the gap discharge device, a front end of the coaxial transmission device is connected to one end of a coaxial cable 304, and the other end of the coaxial cable 304 is connected to the large capacitor 301 through a three-electrode switch 302; and
  • a shock wave pressure probe 308 and a forming plate 309 are arranged in water in the water tank 310, and the shock wave pressure probe 308 and the forming plate 309 are respectively arranged on two sides of a conical energetic material block 218 and located on a path of a shock wave 307 generated by detonation of the conical energetic material block 218; the oscilloscope 311 is connected to the shock wave pressure probe 308, a voltage probe 305, and a current probe 303 respectively; and the voltage probe 305 is arranged on the coaxial cable 304, and the current probe 303 is arranged on grounding wires of the coaxial cable and the three-electrode switch 302.

A continuous pushing device 2 of a gel-like energetic material is installed below the coaxial transmission device 306, and the gel-like energetic material 217 is stored in the continuous pushing device 2 of the gel-like energetic material. The continuous pushing device 2 of the gel-like energetic material is integrally placed in the water tank 301 filled with the water, and the continuous pushing device 2 of the gel-like energetic material forms the conical energetic material block 218 between water gaps after working. After charging the large capacitor 301 in a laboratory, the three-electrode switch 302 is triggered, and electrical energy is injected into the conical energetic material block 218 through the coaxial cable 304. Electric breakdown occurs inside the conical energetic material block 218 and then a plasma channel is formed. The resulting high temperature, radiation, and other effects cause the conical energetic material block 218 to detonate, and push a water medium to form the shock wave 307. A shock wave signal is picked up by the shock wave pressure probe 308, a discharge voltage signal is picked up by the voltage probe 305, and a current signal is picked up by the current probe 303. All of the above signals are recorded and saved by the oscilloscope 311. A shock wave generated by the water gap discharge experimental platform 3 is a free-water shock wave, and can be applied to scenarios such as mechanical machining and forming and electrical pulse cleaning. The forming plate 309 is placed in water, and may be machined by setting appropriate shock wave parameters.

An embodiment of the present disclosure discloses a water gap discharge experimental method, including the following steps:

• • step 1, a continuous pushing device 2 of a gel-like energetic material is installed:
  • step 101: the continuous pushing device 2 of the gel-like energetic material is installed under a coaxial transmission device 306, a water gap with a length of 20 mm is formed between a high-voltage electrode 402 and an energetic material pushing port 216, and the continuous pushing device 2 of the gel-like energetic material is immersed in water.

Step 102: a high-voltage power supply is controlled to charge a large capacitor 301, and charging is stopped when a voltage of the large capacitor 301 reaches 10 kV and stored energy reaches 300 J.

Step 103: pre-discharge of a three-electrode switch 302 is triggered, and a control module 202 picks up a magnetic field signal and then controls a motor 206 to work.

Step 104: the gel-like energetic material 217 is pushed to a position between electrode gaps to form a conical energetic material block 218 with mass of 3.2 g and a height of 20 mm.

Step 2: the conical energetic material block 218 is detonated.

Step 201: a pressure sensor PCB 138 is installed at a distance of 15 cm from a load to measure an amplitude, impulse, and energy density of a shock wave generated by the energetic material.

Step 202: the high-voltage power supply is controlled to charge the large capacitor 301, and charging is stopped when the voltage of the large capacitor 301 reaches 20 kV and the stored energy reaches 1200 J.

Step 203: the three-electrode switch 302 is triggered to form a discharge circuit, and electrical energy is injected into the conical energetic material block 218, and then causes the conical energetic material block to detonate, generating a strong shock wave in water.

As shown in FIG. 14, an embodiment of the present disclosure discloses a rock breaking system, including a portable power supply 503 and a gap discharge device; and the gap discharge device is arranged in a plurality of prefabricated holes 502 in target rock mass 501 with fracturing requirements, and a cable socket 408 of the gap discharge device is connected to the portable power supply 503 through a portable coaxial cable 409.

This embodiment is a dual-hole directional rock breaking scenario. The two parallel holes 502 are formed in a side face of the target rock mass 501 according to the fracturing requirements. A size of each hole 502 is slightly larger than an overall size after the assembly of a continuous pushing device 2 of a gel-like energetic material and an integrated gap discharge pulse source 4. A spacing of the holes 502 is determined jointly according to a tensile strength of the rock mass, target crack morphology and other parameters. Generally speaking, the greater the tensile strength of the rock mass, the more complex the target crack morphology, and the closer the spacing between the holes 502. During field operations, the device is powered by the portable power supply 503, and after the device is connected, a rock breaking operation is started. Dual-hole directional rock breaking will form directional cracks connecting the two holes, which is suitable for application scenarios such as coal seam roof cutting.

As shown in FIG. 15, the present disclosure discloses a rock breaking method using the above rock breaking system, including the following steps:

• • step 1, first, a required fracturing position of rock mass and crack morphology are determined.

Step 2, a certain number of holes with a certain spacing is arranged on a surface of the rock mass according to fracturing requirements.

Step 3, the same number of continuous pushing devices and integrated gap discharge pulse sources as the holes of the rock mass are assembled, and the continuous pushing devices have been pre-filled with gel-like energetic materials.

Step 4, assembled overall devices are installed in the holes of the rock mass.

Step 5, a power supply is controlled to charge, and the continuous pushing devices are started in a pre-discharge manner.

Step 6, the pushing devices push the gel-like energetic materials into gaps to form conical energetic material blocks 218.

Step 7, the power supply is controlled to charge a capacitor.

Step 8, a voltage of the capacitor reaches a limit withstand voltage of a gas switch.

Step 9, the switch breaks down to form a discharge circuit, and energy is injected into the gaps.

Step 10, the conical energetic material blocks 218 are detonated through gap discharge.

Step 11, whether target rock mass achieves a fracturing effect is judged. If it does not meet expectations, step 6 is returned to be performed, and the discharge circuit formed during detonation will restart the continuous pushing devices. If it meets expectations, step 12 is performed.

Step 12, the devices are carried to new working positions, and above steps 2-11 are repeated until all target areas achieve an ideal fracturing effect.

As shown in FIG. 16, an embodiment of the present disclosure discloses a vertical well shale reservoir transformation system, including a control platform 601 and a gap discharge device, wherein the gap discharge device is arranged in a vertical well; and the control platform 601 is connected to the gap discharge device through a cable to detonate a conical energetic material block 218 in a detonation gap, so as to generate a shock wave.

As shown in FIG. 17, an embodiment of the present disclosure discloses a horizontal well shale reservoir transformation system, including a control platform 601 and a gap discharge device, wherein the gap discharge device is arranged in a horizontal well; and the control platform 601 is connected to the gap discharge device through a cable to detonate a conical energetic material block 218 in a detonation gap, so as to generate a shock wave.

This embodiment is shale reservoir transformation in the vertical well and the horizontal well. An installation manner of the device is selected according to a scenario of shale oil reservoir transformation. If it is the vertical well 602, the device is installed at an operation position under the action of gravity with the help of a transmission coaxial cable 603. If it is the horizontal well 610, the device is pushed to an operation position of a heating well 606 with the help of a coiled tubing 607. A ground control platform 601 charges a capacitor through a cable, and a continuous pushing device is started in a pre-discharge manner. The pushing device pushes a gel-like energetic material into a gap to form the conical energetic material block 218, and the ground control platform is started again to charge the capacitor. After a voltage of the capacitor reaches a limit withstand voltage of a gas switch, the switch breaks down to form a discharge circuit. After energy is injected into the gap, the conical energetic material block 218 is detonated to generate a strong shock wave. The strong shock wave is coupled into a reservoir to form a complex fracture network 604. The shock wave is repeated for a specific number of times at the same operation position to manufacture a complex fracture network near a target operation position, thereby increasing a permeability of shale oil. After an expected effect of reservoir transformation is achieved, a conventional method may be directly used to exploit the shale oil in a vertical well scenario. In a horizontal well scenario, in-situ heating is required in the heating well to increase a permeability of low-permeability shale oil 609 in an oil production well 608. Subsequently, the low-permeability shale oil is exploited using a pumping unit 605. In addition to reservoir transformation, this device may further be used for oil-gas unplugging, oil-well production increase, and other scenarios. An operation process and manner are similar to the above.

Referring to FIG. 18, the present disclosure discloses a shale oil reservoir transformation method, including the following steps:

• • step 1, whether an operation scenario is a vertical well or a horizontal well is determined.

Step 2, if it is the vertical well, a device is installed at an operation position under the action of gravity with the help of a transmission coaxial cable 603. If it is the horizontal well, the device is pushed to an operation position of a heating well with the help of a coiled tubing 607.

Step 3, a power supply is controlled on the ground to charge a capacitor through a cable, and a continuous pushing device is started in a pre-discharge manner.

Step 4, the pushing device pushes a gel-like energetic material into a gap to form a conical energetic material block 218.

Step 5, the power supply is controlled on the ground to charge the capacitor through the cable.

Step 6, a voltage of the capacitor reaches a limit withstand voltage of a gas switch.

Step 7, the switch breaks down to form a discharge circuit, and energy is injected into the gap.

Step 8, the conical energetic material block 218 is detonated through gap discharge.

Step 9, step 4 to step 8 are repeated for a specific number of times at the same operation position to manufacture a complex fracture network near a target operation position, thereby increasing a permeability of shale oil.

Step 10, the device is installed to a new operation position with the help of the coaxial cable or the coiled tubing.

Step 11, a reservoir transformation effect is evaluated. If it does not meet expectations, step 1 is returned to re-descend the device to the well. If it meets expectations, step 12 is performed.

Step 12, shale oil is directly exploited in a vertical well scenario, a permeability of low-permeability shale oil is increased by in-situ heating in the heating well in a horizontal well scenario, and the shale oil is exploited in an oil production well.

The above is only a preferred embodiment of the present disclosure, and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure can have various changes and variations. Any modification, equivalent replacement, improvement and the like made in the spirit and principle of the present disclosure shall all be contained in the scope of protection of the present disclosure.