An underwater gas phase rock fracturing method and system thereof

Abstract

The application discloses an underwater gas phase change rock fracturing method and system, and belongs to the technical field of underwater rock breaking construction. The method comprises the steps of construction preparation, positioning drilling, installation of filling and cracking pipe, plugging of the drilling, safety warning and network connection, rock breaking by liquid phase material excitation, confirmation of the release condition of the cracking pipe and slag removal. The method accurately designs construction parameters according to rock hardness, and the drilling diameter and hole distance are determined according to the compressive strength. The length of the cracking pipe is matched with the hole depth, and strict operation requirements are provided in the aspects of filling, plugging, warning and excitation. The system comprises gas phase change, temperature control and monitoring, pressure monitoring and feedback, and can accurately control the gas phase change process. The application can accurately match the geological conditions, improve the construction efficiency and safety, reduce the cost, improve the construction quality, reduce the environmental impact, and is suitable for various underwater rock engineering, and provides an efficient and environmentally-friendly solution for underwater rock breaking construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater rock breaking construction, in particular to a method for rock breaking by using gas phase change in underwater environment with high requirements for ecological environment of construction area and related system. BACKGROUND

[0002] In recent years, with the development and progress of economic construction, construction operation pays more and more attention to the protection of ecological environment of construction area. At the same time, the popularization of green construction technology has become a trend, especially the protection of water environment, such as some projects involving underwater rock breaking in sensitive areas that cannot be affected by intense vibration or sensitive areas with high requirements for aquatic environment and high requirements for ecological protection. Therefore, the implementation of the traditional method of chiseling and breaking will be limited, and the underwater gas phase change rock breaking method can be used at that time.

[0003] Patent application CN202311411145.6 A hard rock directional fracturing method coupled with hydraulic fracturing and carbon dioxide phase change belongs to the technical field of coal mines. It includes the following steps: S1. Site selection: according to the engineering geological conditions of the site rock mass and the design scheme, the excavation construction area is determined; S2. Drilling hole cleaning: according to the engineering geological conditions of the site rock mass and the design scheme, drill the blast hole to the designed depth in the designed excavation area, and clean the hole after the construction is completed to remove the impurities in the hole; S3. Hydraulic fracturing; S4. Secondary hole cleaning; S5. Installing equipment; S6. Blocking the drill hole; S7. Starting blasting. By pre-weakening the rock mass strength through hydraulic fracturing, the mechanical properties of the rock mass are reduced and initial cracks are induced in the rock mass, which can reduce the initial pressure of the rock mass under the action of carbon dioxide phase change blasting pressure, and guide the expansion of the blast-induced cracks, so as to make the cracks expand along the predetermined direction, achieving the purpose of directional fracturing.

[0004] Patent application CN202410606327.7 discloses a method for open-cut rock excavation based on supercritical fluid impact rock breaking equipment, belonging to the field of rock excavation technology. By using a pressure sensor to monitor the pressure value of the deflagration gas in real time, the high-pressure impact energy can be precisely adjusted for different construction scenarios or rock types, improving rock breaking quality and increasing operational efficiency. This method for open-cut rock excavation based on supercritical fluid impact rock breaking equipment includes the following steps: S1, site clearing; S2, opening the initial free face; S3, drilling; S4, inserting the pressure relief head into the hole; S5, filling the pressurized energy-concentrating agent; S6, sealing the hole: activating the packer to compress the sealing capsule until it fully expands, completing the sealing; S7, covering with blasting blankets or sandbags; S8, safety precautions and air filling; S9, activation: setting the gas release pressure value according to the drilling parameters and the rock conditions around the hole to activate the combustion reaction of the pressurized energy-concentrating agent; S10, on-site inspection; S11, equipment relocation and mechanical cleaning. It achieves rock-breaking effects that are energy-controllable, safe, and environmentally friendly, improves construction efficiency, reduces noise and environmental impact, and is suitable for medium-hard and hard rock conditions. Its rock-breaking efficiency is about 2-3 times that of mechanical crushing.

[0005] However, none of the above-mentioned existing technologies take into account the types of underwater rocks and the complex underwater geological environment, and cannot accurately control the crushing effect for different types of rocks. Summary of the Invention

[0006] To address the problem that existing phase change methods are not applicable to various underwater rock types and complex underwater geological environments, this invention selects appropriate borehole diameters and spacing based on the rock hardness. When underwater rocks are broken, the vibration, noise, solid-liquid pollution, and overall impact on the original aquatic environment are minimized, thus playing a role in ecological and water resource protection.

[0007] To achieve the above objectives, the present invention provides an underwater gas phase transformation rock fracturing method, comprising the following steps:

[0008] S1, Construction preparation, including removing the overburden and opening up the lateral free surface;

[0009] S2, positioning boreholes, the borehole diameter and spacing are determined based on the compressive strength of the rock on site;

[0010] S3, Install the fracturing tube and fill it with liquid phase material. The outer diameter of the fracturing tube should be smaller than the borehole diameter, and the length of the fracturing tube should be selected according to the borehole depth.

[0011] S4, sealing the borehole, using a sealing device to seal the borehole;

[0012] S5, security alert and network connectivity;

[0013] S5, activates liquid phase materials, utilizes the phase transformation of liquid into gas under specific temperature and pressure conditions to generate expansion force to pressurize and crack rocks for fracturing;

[0014] S5. Equipment operators confirm the release status of the rupture tube. If the rupture tube is found to be unactivated, report it immediately, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the excitation network. If the rupture tube is not activated due to the excitation network, it can be reconnected for activation. If the rupture tube is not activated for other reasons, it should be destroyed.

[0015] S6, Slag Removal.

[0016] Furthermore, in S2, the borehole diameter is determined based on the compressive strength of the rock at the site, specifically as follows:

[0017] when At that time, borehole diameter D is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 200 mm.

[0018] when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa.

[0019] when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa.

[0020] when At that time, borehole diameter D is in mm. The hardness of rock is expressed in MPa.

[0021] Furthermore, in S2, the borehole spacing is determined based on the compressive strength of the rock at the site, specifically as follows:

[0022] when At that time, the hole spacing L is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 1500 mm.

[0023] when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa.

[0024] when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa.

[0025] when At that time, borehole diameter L is in mm. The hardness of rock is expressed in MPa.

[0026] Furthermore, the filling pressure of the fracturing tube is controlled between 5 MPa and 10 MPa.

[0027] Furthermore, the outer diameter of the fracturing tube should be 10mm to 20mm smaller than the borehole diameter; the length of the fracturing tube should be selected according to the borehole depth.

[0028] Furthermore, the length of the fracture-inducing tube should be selected based on the borehole depth, specifically as follows:

[0029] For each borehole depth H range, the length L of the fracturing tube can be determined by L=a·H+b, where a and b are coefficients determined according to the borehole depth range;

[0030] For 1800mm≤H≤2800mm, take a=0.5 and b=0, L=0.5·H;

[0031] For 2800mm < H≤ 3800mm, take a=0.5 and b=-400, L=0.5·H-400;

[0032] For 3800mm < H≤4500mm, take a=0.5 and b=-1000, L=0.5·H-1000.

[0033] Furthermore, before filling with liquid phase material, the safety valve, fracturing tube, excitation element, and excitation lead wire should be checked to ensure they are intact.

[0034] Furthermore, the fracturing tube should have a sufficiently long excitation lead wire, and the lead wire should be protected from damage when plugging the borehole; the borehole plugging length should not be less than the distance from the fracturing tube to the lateral free surface.

[0035] Furthermore, in step S5, the warning range should be determined according to the water depth. When the water depth is greater than 4m, the warning range should not be less than 30m; when the water depth is between 2m and 4m, the warning range should not be less than 60m; when the water depth is less than 2m, the warning range should not be less than 100m. After taking warning measures and confirming safety, the rupture tube should be activated immediately. After activation, wait for more than 5 minutes before entering the site for inspection.

[0036] The present invention also provides a system for the above-described underwater gas phase transformation rock fracturing method, comprising:

[0037] The gas phase change system can generate high-pressure gas. The pressure adjustment range is determined according to the rock hardness requirements. It has good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas.

[0038] The temperature control and monitoring system is equipped with temperature sensors in the gas phase change system to monitor gas temperature changes in real time. It is also equipped with heating or cooling elements. When the gas temperature deviates from the optimal temperature range required for phase change, the temperature is adjusted in time to ensure that the gas undergoes a precise phase change when it reaches the predetermined position inside the rock. The specific temperature range for temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas.

[0039] The pressure monitoring and feedback system installs pressure sensors in the gas phase change system to monitor gas pressure changes in real time and transmits the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system precisely controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generator in a timely manner based on the pressure feedback information to ensure the stability and effectiveness of the rock-fracture process.

[0040] The beneficial effects of this invention are:

[0041] Precisely adapting to rock characteristics: Determine the borehole diameter and spacing based on the rock's compressive strength, avoiding a one-size-fits-all design, and ensuring that construction parameters are highly matched with actual geological conditions, thereby improving scientific rigor and rationality.

[0042] Improving construction efficiency: Selecting appropriate drilling equipment and construction methods reduces the number of drilling operations and equipment adjustment frequency for rocks with high hardness; optimizing blasting and other process effects through appropriate hole spacing design reduces rework and equipment failure, ensures construction continuity and stability, and improves time and resource utilization efficiency.

[0043] Ensuring construction safety: A reasonable design can better control the stress distribution and energy release during construction, avoid the risk of excessive crushing and collapse of low compressive strength rocks, ensure the effective transfer and release of energy in the construction of high compressive strength rocks, reduce safety accidents caused by energy accumulation, and help to predict risk points and take safety measures.

[0044] Reduce costs: Improve construction efficiency to reduce labor, material and time costs; precise design avoids material waste, extends the service life of construction equipment, and reduces equipment wear and maintenance costs.

[0045] Improve construction quality: Set specific fracturing tube length calculation formulas for different borehole depth ranges, match them with the borehole depth, so that the rock is broken more evenly, achieves the expected fracturing effect, and avoids material waste and reconstruction. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a flowchart of the underwater gas phase transformation rock fracturing method. Detailed Implementation

[0048] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of a descriptive feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets.

[0050] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0051] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0052] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various components of the invention are relative rather than absolute. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, these directional indications also change accordingly.

[0053] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0055] This embodiment utilizes the method of instantaneously changing certain liquids from a liquid to a gaseous state under different temperature and pressure conditions, causing cracking and fracturing. Phase change expansion rock fracturing should be initiated simultaneously with the flow. Storage tanks should be filled as needed and not stored for extended periods; storage tanks and filling equipment with corrosion, damage, cracks, or other defects should be replaced promptly; storage tanks and equipment should be placed in a ventilated, cool place, and should not be subjected to violent shaking, collisions, or direct sunlight. During liquid transportation and filling operations, personnel should maintain a safe distance from the vent. Storage tanks that are not used within 3 days should be emptied and recycled.

[0056] Figure 1 This is the construction flowchart in this embodiment, including...

[0057] Includes the following steps:

[0058] S1, Construction preparation, including removing the overburden and opening up the lateral free surface;

[0059] If the cover layer thickness is greater than 0.3m, the cover layer removal operation is carried out; if the cover layer thickness is less than or equal to 0.3m, the positioning drilling stage is started.

[0060] S2, positioning boreholes, the borehole diameter and spacing are determined based on the compressive strength of the rock on site;

[0061] The drilling depth should be determined based on the on-site rock surface elevation, the design bottom elevation, and the over-depth value. A borehole inspection should be conducted after drilling is completed. Drilling parameters should be determined based on rock strength, joint development, and free surfaces.

[0062]

[0063] The borehole diameter is determined based on the compressive strength of the rock at the site, specifically:

[0064] when At that time, borehole diameter D is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 200 mm.

[0065] when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa.

[0066] when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa.

[0067] when At that time, borehole diameter D is in mm. The hardness of rock is expressed in MPa.

[0068] The borehole spacing is determined based on the compressive strength of the rock at the site, specifically as follows:

[0069] when At that time, the hole spacing L is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 1500 mm.

[0070] when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa.

[0071] when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa.

[0072] when At that time, borehole diameter L is in mm. The hardness of rock is expressed in MPa.

[0073] This design fully considers the key factor of rock compressive strength, with different borehole diameters and spacings corresponding to rocks of varying strengths. This design precisely adapts to the characteristics of the rock, avoiding a one-size-fits-all approach and ensuring a high degree of matching between construction parameters and actual geological conditions, thus improving the scientific rigor and rationality of the construction process. Through precise parameter design, more suitable drilling equipment and construction methods can be selected during construction. For example, for harder rocks, a larger borehole diameter and a reasonable spacing can reduce the number of drilling operations and the frequency of equipment adjustments, thereby accelerating the construction progress and improving overall efficiency. Simultaneously, a suitable spacing design helps optimize the effects of blasting or other construction techniques, further enhancing construction efficiency. This reduces rework and equipment failures caused by mismatched construction parameters, ensuring the continuity and stability of construction and improving efficiency in terms of both time and resource utilization.

[0074] Meanwhile, a well-designed borehole diameter and spacing can better control stress distribution and energy release during construction. In rocks with low compressive strength, smaller borehole diameters and appropriate spacing can avoid safety risks such as excessive fracturing and collapse; while in rocks with high compressive strength, larger diameters and spacing ensure the effective transfer and release of construction energy, reducing safety accidents caused by energy accumulation. This refined design based on rock characteristics helps construction personnel anticipate potential risks during construction and take corresponding safety measures, thereby significantly improving construction safety.

[0075] By improving construction efficiency and reducing rework and equipment failures, the design directly lowers labor, material, and time costs. Simultaneously, precise design avoids unnecessary material waste. In the long run, this design helps extend the lifespan of construction equipment, reducing equipment wear and maintenance costs, further lowering overall construction costs. In conclusion, determining borehole diameter and spacing based on the compressive strength of the rock at the site has numerous advantages and beneficial effects, playing a crucial role in improving construction efficiency, ensuring construction safety, reducing costs, enhancing construction quality, protecting the environment, and increasing adaptability.

[0076] S3, Install the fracturing tube and fill it with liquid phase material. The outer diameter of the fracturing tube should be smaller than the borehole diameter, and the length of the fracturing tube should be selected according to the borehole depth.

[0077] The outer diameter of the fracturing tube should be 10mm to 20mm smaller than the borehole diameter. The length of the fracturing tube should be selected according to the borehole depth and should meet the proportional requirements.

[0078] For each borehole depth H range, the length L of the fracturing tube can be determined by L=a·H+b, where a and b are coefficients determined according to the borehole depth range;

[0079] For 1800mm≤H≤2800mm, we can take a=0.5 and b=0, which means L=0.5·H;

[0080] For 2800mm < H≤ 3800mm, we can take a=0.5 and b=-400, which means L=0.5·H-400;

[0081] For 3800mm < H≤4500mm, we can take a=0.5 and b=-1000, which means L=0.5·H-1000.

[0082] Specific formulas for calculating the length of fracturing tubes are established for different borehole depths, ensuring a proper match between the tube length and the borehole depth. Construction personnel can quickly calculate the required tube length based on the borehole depth, eliminating the need for tedious measurements and adjustments, reducing preparation time, and improving overall construction progress. When switching between different borehole depths, the clear and simple formulas allow personnel to quickly adapt and prepare the appropriate fracturing tubes, ensuring a smooth construction process and preventing delays caused by unsuitable tube lengths. Appropriate tube lengths maximize the fracturing effect. At different borehole depths, the stress conditions and fracturing requirements of the rock vary. This segmented design allows for more effective transmission and distribution of fracturing energy across different depth ranges. For example, shorter fracturing tubes in deeper boreholes prevent excessive energy concentration at the bottom or opening, resulting in more uniform rock fracturing, improved construction quality, and the achievement of the desired fracturing effect. This also avoids the overuse or waste of fracturing tubes. Without precise design based on the borehole depth, the fracturing tube may be too long, leading to material waste, or too short, failing to achieve the fracturing effect and requiring rework. This segmented design allows for accurate calculation of the fracturing tube length based on the actual borehole depth, enabling precise material procurement and usage, thereby reducing fracturing tube consumption and material costs.

[0083] In one embodiment, the hole depth is 1800mm~2800mm, and the length of the fracturing tube is preferably 800mm~1400mm. For a hole depth of 2800mm~3800mm, the length of the fracturing tube is preferably 1400mm~2000mm. For a hole depth of 3800mm~4500mm, the length of the fracturing tube is preferably 2000mm~2500mm.

[0084] Before filling with liquid material, check that the safety valve, fracturing tube, excitation element, and excitation lead wire are intact. Connect the filling equipment to fill the fracturing tube with liquid material. The filling pressure should be controlled between 5MPa and 10MPa. In-hole filling is preferred. If in-hole filling is difficult, external filling can be used. In hot weather, the fracturing tube should be cooled before filling. Sufficient length of excitation lead wire should be reserved in the fracturing tube. Avoid damaging the lead wire when plugging the borehole. The borehole plugging length should not be less than the distance from the fracturing tube to the lateral free surface.

[0085] S4, sealing the borehole, using a sealing device to seal the borehole;

[0086] For borehole plugging, a medium with a high friction coefficient and density should be selected. Excitation elements and fracturing tubes used in the same operation should preferably be from the same manufacturer and batch.

[0087] S5, security alert and network connectivity;

[0088] The warning range should be determined according to the water depth. When the water depth is greater than 4m, the warning range should not be less than 30m; when the water depth is between 2m and 4m, the warning range should not be less than 60m; when the water depth is less than 2m, the warning range should not be less than 100m. After taking warning measures and confirming safety, the rupture tube should be activated immediately. After activation, wait for more than 5 minutes before entering the site for inspection.

[0089] S5, activates liquid phase materials, utilizes the phase transformation of liquid into gas under specific temperature and pressure conditions to generate expansion force to pressurize and crack rocks for fracturing;

[0090] The excitation elements should be tested using a dedicated instrument with an output current of less than 30mA to 40mA. This testing should preferably be performed before the fracturing tube is filled with liquid material and after the manhole is plugged. The excitation network should preferably be connected in series, following the direction of water flow. The network should be short-circuited before excitation. Before connecting the network, the resistance value of each excitation element and wire should be tested to confirm that the resistance value is stable, the connections are secure, and the insulation is good.

[0091] S5. Equipment operators confirm the release status of the rupture tube. If the rupture tube is found to be unactivated, report it immediately, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the excitation network. If the rupture tube is not activated due to the excitation network, it can be reconnected for activation. If the rupture tube is not activated for other reasons, it should be destroyed.

[0092] S6. After a section of construction is completed, the debris should be removed promptly.

[0093] Another embodiment discloses a system for the above-described underwater gas phase transformation rock fracturing method, comprising:

[0094] The gas phase change system can generate high-pressure gas. The pressure adjustment range is determined according to the rock hardness requirements. It has good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas.

[0095] The temperature control and monitoring system is equipped with temperature sensors in the gas phase change system to monitor gas temperature changes in real time. It is also equipped with heating or cooling elements. When the gas temperature deviates from the optimal temperature range required for phase change, the temperature is adjusted in time to ensure that the gas undergoes a precise phase change when it reaches the predetermined position inside the rock. The specific temperature range for temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas.

[0096] The pressure monitoring and feedback system installs pressure sensors in the gas phase change system to monitor gas pressure changes in real time and transmits the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system precisely controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generator in a timely manner based on the pressure feedback information to ensure the stability and effectiveness of the rock-fracture process.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for underwater gas phase transformation fracturing of rocks, characterized in that, Includes the following steps: S1, Construction preparation, including removing the overburden and opening up the lateral free surface; S2, positioning boreholes, the borehole diameter and spacing are determined based on the compressive strength of the rock on site; S3, Install the fracturing tube and fill it with liquid phase material. The outer diameter of the fracturing tube is smaller than the borehole diameter, and the length of the fracturing tube is selected according to the borehole depth. S4, sealing the borehole, using a sealing device to seal the borehole; S5, security alert and network connectivity; The liquid phase material is activated, and the liquid transforms into gas under specific temperature and pressure conditions to generate expansion force, pressurize and expand the rock to break it. Equipment operators should confirm the release status of the rupture tube. If the rupture tube is found to be unactivated, report it immediately, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the excitation network. If the rupture tube is not activated due to the excitation network, it can be reconnected for activation. If the rupture tube is not activated for other reasons, it should be destroyed. S6, slag removal; Sufficient length of excitation lead wire should be reserved in the fracturing tube, and the lead wire should be protected from damage when plugging the borehole; the plugging length of the borehole should not be less than the distance from the fracturing tube to the lateral free surface; The system for the underwater gas phase transformation rock fracturing method includes: The gas phase change system can generate high-pressure gas. The pressure adjustment range is determined according to the rock hardness requirements. It has good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas. The temperature control and monitoring system is equipped with temperature sensors in the gas phase change system to monitor gas temperature changes in real time. It is also equipped with heating or cooling elements. When the gas temperature deviates from the optimal temperature range required for phase change, the temperature is adjusted in time to ensure that the gas undergoes a precise phase change when it reaches the predetermined position inside the rock. The specific temperature range for temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas. The pressure monitoring and feedback system installs pressure sensors in the gas phase change system to monitor gas pressure changes in real time and transmits the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system precisely controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generator in a timely manner based on the pressure feedback information to ensure the stability and effectiveness of the rock-fracture process.

2. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, In S2, the borehole diameter is determined based on the compressive strength of the rock at the site, specifically as follows: when At that time, borehole diameter D is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 200 mm. when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa. when At that time, borehole diameter D is in mm. Rock hardness is expressed in MPa. when At that time, borehole diameter D is in mm. The hardness of rock is expressed in MPa.

3. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, In S2, the borehole spacing is determined based on the compressive strength of the rock at the site, specifically as follows: when At that time, the hole spacing L is in mm. The value represents the rock hardness in MPa, but the upper limit of D must be limited to within 1500 mm. when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa. when At that time, the hole spacing L is in mm. Rock hardness is expressed in MPa. when At that time, the hole spacing L is in mm. The hardness of rock is expressed in MPa.

4. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, The filling pressure of the fracturing tube is controlled between 5 MPa and 10 MPa.

5. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, The outer diameter of the fracturing tube is 10mm to 20mm smaller than the borehole diameter; the length of the fracturing tube is selected according to the borehole depth.

6. The underwater gas phase transformation rock fracturing method according to claim 5, characterized in that, The length of the fracture tube is selected based on the borehole depth, specifically as follows: For each borehole depth H range, the length L of the fracturing tube is determined by L=a·H+b, where a and b are coefficients determined according to the borehole depth range; For 1800mm≤H≤2800mm, take a=0.5 and b=0, L=0.5·H; For 2800mm < H≤ 3800mm, take a=0.5 and b=-400, L=0.5·H-400; For 3800mm < H≤4500mm, take a=0.5 and b=-1000, L=0.5·H-1000.

7. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, Before filling with liquid phase material, check that the safety valve, fracturing tube, excitation element and excitation lead wire are intact.

8. The underwater gas phase transformation rock fracturing method according to claim 1, characterized in that, In step S5, the warning range is determined according to the water depth. When the water depth is greater than 4m, the warning range should not be less than 30m; when the water depth is between 2m and 4m, the warning range should not be less than 60m; when the water depth is less than 2m, the warning range should not be less than 100m. After taking warning measures and confirming safety, the rupture tube should be activated immediately. After activation, wait for more than 5 minutes before entering the site for inspection.

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