Calculation method for influence range of carbon dioxide phase change fracturing in deep shaft

Abstract

The invention discloses a method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft, and the method comprises the steps: dividing a carbon dioxide phase change fracturing process into a dynamic impact stage and a quasi-static fracturing stage, and considering the initial crustal stress state and the pressure caused by the carbon dioxide phase change in the two stages; stress field distribution around the hole in the two stages is obtained through calculation, and then the range of a crack initiation area and the range of a crack propagation area are obtained through calculation based on the dynamic tensile stress and the crack strength factor. According to the method for calculating the influence range of the carbon dioxide phase change fracturing of the deep hole, the particularity of the carbon dioxide phase change fracturing is considered in the provided method, especially the stress characteristics of the rock around the hole in different fracturing stages, and convenience is provided for engineering scheme design of the carbon dioxide phase change fracturing.

Description

Technical Field

[0001] The invention relates to the field of underground structure transformation and development, and in particular to a method for calculating the influence range of carbon dioxide phase change cracking in a deep vertical shaft. Background Art

[0002] Blasting is a commonly used technical means in the excavation of underground projects such as tunnels, adits, and shafts in deep geotechnical engineering, as well as in the mining of underground resources such as coal, unconventional oil and gas, and uranium. Traditional blasting uses explosives as an energy source, which has disadvantages such as high construction difficulty, strict use conditions, and low predictability. In recent years, carbon dioxide phase change fracturing, as a new type of non-explosive blasting technology, has gradually gained favor and has been widely used in deep engineering due to its high controllability, safety, and environmental friendliness. By filling liquid carbon dioxide into a special carbon dioxide fracturing tube, the heat is released by the excitation tube to induce a rapid phase change of the liquid carbon dioxide. The huge energy generated by the phase change expansion of carbon dioxide is used to impact the rock mass and cause it to break.

[0003] The calculation of the blasting influence range is the basic work of deep rock blasting, which directly affects the design of the entire blasting plan, especially the arrangement of blast holes. At present, in the calculation of the influence range of carbon dioxide phase change fracturing, the blasting theory based on traditional explosive blasting is still used. The rock formation around the blast hole is divided into a crushing zone, a crack zone and a vibration zone from the inside to the outside. The stress distribution of the rock formation is obtained according to the shock wave attenuation model, and then the dynamic tensile strength and dynamic tensile strength of the rock are combined to calculate the range of the crushing zone and the crack zone respectively. However, some experimental studies have found that the fracturing characteristics of carbon dioxide phase change on rock formations are significantly different from those of explosive blasting. Compared with the high pressure peak, short duration and high frequency of explosive blasting, the pressure peak of carbon dioxide blasting is lower, the duration is longer and the frequency is lower. In particular, the pressure drop after the peak is more gradual. As a result, in many cases the crushing zone is not obvious, and the development of the fracture zone also has a staged characteristic. In the dynamic impact stage where the pressure rises rapidly, the shock wave generates several shorter radial cracks around the hole. In the quasi-static fracturing stage where the pressure drops slowly, carbon dioxide continues to expand into the cracks to produce a fracturing effect, causing some of the cracks to continue to expand until they stop.

[0004] In summary, the current calculation method of the influence range of carbon dioxide phase change fracturing based on the blasting theory of traditional explosive blasting does not take into account the difference between carbon dioxide phase change fracturing and explosive blasting, and cannot reflect the characteristics of carbon dioxide phase change fracturing. Therefore, it is urgent to provide a calculation method of the influence range of carbon dioxide phase change fracturing in deep shafts, which can calculate the range of the crack initiation zone and the crack propagation zone according to the particularity of carbon dioxide phase change fracturing, which is of great significance to the engineering design of carbon dioxide phase change fracturing. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft in view of the defects in the prior art, so as to facilitate the calculation of the influence range of fracturing in the process of deep hole blasting using a carbon dioxide phase change fracturing device.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The present invention provides a method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft, comprising:

[0008] The carbon dioxide phase change fracturing process is divided into two stages: dynamic impact stage and quasi-static fracturing stage. Considering the initial ground stress state and the pressure caused by the carbon dioxide phase change in the two stages, the stress field distribution around the hole in the two stages is calculated respectively. Then, based on the dynamic tensile stress and crack intensity factor, the range of the crack initiation zone and the crack propagation zone are calculated respectively.

[0009] Furthermore, the method of the present invention is an initial ground stress state before the dynamic impact stage, including a method for calculating the initial stress distribution:

[0010] Taking the center of the deep hole as the origin of the polar coordinates and the direction of the maximum horizontal geostress as the x-axis of the polar coordinates, the initial stress distribution around the hole under the action of horizontal geostress is calculated:

[0011]

[0012] Among them, σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; τ rθ0 is the initial shear stress at position (r, θ); σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates.

[0013] Furthermore, the specific method of the dynamic impact stage in the method of the present invention includes:

[0014] Calculate the impact pressure on the deep hole wall caused by carbon dioxide phase change cracking during the dynamic impact stage;

[0015] Calculate the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure;

[0016] According to the impact pressure and dynamic stress distribution, the conditions for crack initiation in the dynamic impact stage are determined;

[0017] The crack initiation range around the hole in the dynamic impact stage is determined according to the dynamic stress distribution, and the distribution of the crack initiation range around the hole in the dynamic impact stage is plotted in polar coordinates.

[0018] Furthermore, the formula for calculating the impact pressure P1 caused on the deep hole wall during the carbon dioxide phase change fracturing in the dynamic impact stage of the present invention is:

[0019]

[0020] Among them, P1 is the impact pressure caused by carbon dioxide phase change cracking on the deep hole wall during the dynamic impact stage; n is the pressure increase multiple; P c is the rupture pressure of carbon dioxide-induced fracture pipe; d c is the diameter of the carbon dioxide fracturing tube; d b is the diameter of the deep hole; γ is the exponential parameter;

[0021] The formula for calculating the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure is:

[0022]

[0023] Among them, σ rd , σ θd are the dynamic radial stress and dynamic annular stress caused by the stress wave generated by the impact pressure at a distance r from the center of the deep hole; P1 is the impact pressure caused on the wall of the deep hole during the phase change cracking of carbon dioxide in the dynamic impact stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates.

[0024] Furthermore, the conditions for judging the cracking in the dynamic impact stage of the present invention are:

[0025]

[0026] Among them, σ θ1 (r, θ) is the total radial stress around the hole during the dynamic impact stage; σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; P1 is the impact pressure on the deep hole wall caused by carbon dioxide phase change fracturing in the dynamic impact stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates; σ t is the uniaxial tensile strength of rock.

[0027] Furthermore, the specific method of the quasi-static fracturing stage in the method of the present invention includes:

[0028] Calculate the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage;

[0029] Calculate the quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at the distance from the center of the deep hole;

[0030] Calculate the radial stress around the hole during the quasi-static fracturing stage;

[0031] The conditions for determining crack propagation during the quasi-static fracturing stage are that the stress intensity factor of the crack is greater than the fracture toughness of the rock;

[0032] The formula for the crack extension condition in the static fracturing stage is converted into an equation about the radius and angle of polar coordinates through the Gauss-Legendre numerical integration formula. The range of crack extension in the quasi-static fracturing stage is obtained and its distribution is plotted in polar coordinates, that is, the influence range of carbon dioxide phase change fracturing in deep vertical wells is obtained.

[0033] Furthermore, in the method of the present invention, the formula for calculating the quasi-static pressure P2 caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage is:

[0034] P2=KP c

[0035] Among them, P2 is the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage; K is the carbon dioxide gas attenuation coefficient; P c is the carbon dioxide-induced fracture pipe rupture pressure;

[0036] The quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at a distance r from the center of the deep hole are calculated as follows:

[0037]

[0038] Among them, σ rs (r), σ θs (r) are the quasi-static radial stress and quasi-static annular stress caused by the quasi-static pressure at a distance r from the center of the deep hole; P2 is the quasi-static pressure caused by carbon dioxide on the wall of the deep hole during the quasi-static fracturing stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates.

[0039] Furthermore, the formula for calculating the radial stress around the hole in the quasi-static fracturing stage in the method of the present invention is:

[0040]

[0041] Among them, σ θ2 (r, θ) is the radial stress around the hole during the quasi-static fracturing stage; σ θ0(r, θ) is the initial hoop stress at position (r, θ); σ θs (r) is the quasi-static hoop stress caused by the quasi-static pressure at a distance r from the center of the deep hole; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole.

[0042] Furthermore, the conditions for crack propagation in the quasi-static fracturing stage in the method of the present invention are specifically:

[0043] The condition K for crack extension in the quasi-static fracturing stage I The stress intensity factor of the crack is greater than the fracture toughness of the rock, and the formula is:

[0044]

[0045] Among them, K I is the crack extension condition in the quasi-static fracturing stage; a=rr b is the total length of the crack; σ θ2 (r b +x,θ) is (r b =K is the radial stress around the hole in the quasi-static fracturing stage at the position of (x, θ); x is the distance between a point on the crack and the starting point of the crack on the hole wall; K IC is the fracture toughness of rock, C1, C2, and C3 are coefficients.

[0046] The present invention provides a system for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft, comprising:

[0047] a memory for storing executable computer programs;

[0048] The processor is used to implement the above-mentioned method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical well when executing the executable computer program stored in the memory.

[0049] The beneficial effects produced by the present invention are:

[0050] The present invention provides a method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft. The method provided can take into account the particularity of carbon dioxide phase change fracturing while considering the influence of the initial ground stress state, and divides the carbon dioxide phase change fracturing process into two stages: a dynamic impact stage and a quasi-static fracturing stage. The range of the crack initiation zone and the crack propagation zone is calculated according to the stress field distribution around the hole in these two stages, so as to provide a reference for the engineering scheme design of carbon dioxide phase change fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0052] Figure 1 It is a schematic diagram of the hole-circumferential stress analysis at each stage in a method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft of the present invention;

[0053] Figure 2 Schematic diagram of the influence range of carbon dioxide phase change cracking calculated in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] Example 1

[0056] like Figure 1 As shown, the method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical shaft according to an embodiment of the present invention includes:

[0057] The carbon dioxide phase change fracturing process is divided into two stages: the dynamic impact stage and the quasi-static fracturing stage. Considering the initial ground stress state and the pressure caused by the carbon dioxide phase change in the two stages, the stress field distribution around the hole in the two stages is calculated respectively, and then based on the dynamic tensile stress and crack intensity factor, the range of the crack initiation zone and the crack extension zone is calculated respectively. Among them:

[0058] First, the center of the deep hole is taken as the origin of the polar coordinates and the direction of the maximum horizontal geostress is taken as the x-axis of the polar coordinates to calculate the initial stress distribution around the hole under the action of horizontal geostress.

[0059] Dynamic impact phase, including:

[0060] Calculate the impact pressure on the deep hole wall caused by carbon dioxide phase change cracking during the dynamic impact stage;

[0061] Calculate the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure;

[0062] According to the impact pressure and dynamic stress distribution, the conditions for crack initiation in the dynamic impact stage are determined;

[0063] The crack initiation range around the hole in the dynamic impact stage is determined according to the dynamic stress distribution, and the distribution of the crack initiation range around the hole in the dynamic impact stage is plotted in polar coordinates.

[0064] Quasi-static fracturing stage:

[0065] Calculate the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage;

[0066] Calculate the quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at the distance from the center of the deep hole;

[0067] Calculate the radial stress around the hole during the quasi-static fracturing stage;

[0068] The conditions for determining crack propagation during the quasi-static fracturing stage are that the stress intensity factor of the crack is greater than the fracture toughness of the rock;

[0069] The formula for the crack extension condition in the static fracturing stage is converted into an equation about the radius and angle of polar coordinates through the Gauss-Legendre numerical integration formula. The range of crack extension in the quasi-static fracturing stage is obtained and its distribution is plotted in polar coordinates, that is, the influence range of carbon dioxide phase change fracturing in deep vertical wells is obtained.

[0070] Example 2

[0071] Based on Example 1, the embodiment of the present invention provides a more complete and specific calculation method, which specifically includes the following steps:

[0072] 1) Taking the center of the deep hole as the origin of the polar coordinates and the direction of the maximum horizontal geostress as the x-axis of the polar coordinates, the initial stress distribution around the hole under the action of horizontal geostress is calculated using equations (1) to (3). The formula is:

[0073]

[0074]

[0075] In formulas (1) to (3), σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; τ rθ0 is the initial shear stress at position (r, θ); σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates;

[0076] 2) Formula (4) is used to calculate the impact pressure P1 caused by carbon dioxide phase change cracking on the deep hole wall during the dynamic impact stage. Formula (4) is:

[0077]

[0078] In formula (4), P1 is the impact pressure on the deep hole wall caused by carbon dioxide phase change cracking in the dynamic impact stage; n is the pressure increase multiple; P c is the rupture pressure of carbon dioxide-induced fracture pipe; d c is the diameter of the carbon dioxide fracturing tube; d bis the diameter of the deep hole; γ is the exponential parameter, which is 3;

[0079] 3) Formula (5) is used to calculate the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure. Formula (5) is:

[0080]

[0081] In formula (5), σ rd , σ θd are the dynamic radial stress and dynamic annular stress caused by the stress wave generated by the impact pressure at a distance r from the center of the deep hole; P1 is the impact pressure caused on the wall of the deep hole during the phase change cracking of carbon dioxide in the dynamic impact stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates;

[0082] 4) Formula (6) is the condition for cracking in the dynamic impact stage:

[0083]

[0084] In formula (6), σ θ1 (r, θ) is the total radial stress around the hole during the dynamic impact stage; σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; P1 is the impact pressure on the deep hole wall caused by carbon dioxide phase change fracturing in the dynamic impact stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates; σ t is the uniaxial tensile strength of rock;

[0085] 5) According to the crack initiation range around the hole in the dynamic impact stage determined by formula (5), the distribution of the crack initiation range around the hole in the dynamic impact stage is plotted in polar coordinates;

[0086] 6) Formula (7) is used to calculate the quasi-static pressure P2 caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage. Formula (7) is:

[0087] P2=KP c (7)

[0088] Where, P2 is the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage; K is the carbon dioxide gas attenuation coefficient; P c is the carbon dioxide-induced fracture pipe rupture pressure;

[0089] 7) The quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at a distance r from the center of the deep hole are:

[0090]

[0091] In formulas (8) and (9), σ rs (r), σ θs (r) are the quasi-static radial stress and quasi-static annular stress caused by the quasi-static pressure at a distance r from the center of the deep hole; P2 is the quasi-static pressure caused by carbon dioxide on the wall of the deep hole during the quasi-static fracturing stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates;

[0092] 8) Formula (10) is used to calculate the radial stress around the hole in the quasi-static fracturing stage. Formula (10) is:

[0093]

[0094] In formula (10), σ θ2 (r, θ) is the radial stress around the hole during the quasi-static fracturing stage; σ θ0 (r, θ) is the initial hoop stress at position (r, θ); σ θs (r) is the quasi-static hoop stress caused by the quasi-static pressure at a distance r from the center of the deep hole; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole; r and θ are the radius and angle of the polar coordinates; P2 is the quasi-static pressure caused by carbon dioxide on the wall of the deep hole during the quasi-static fracturing stage;

[0095] 9) Crack propagation condition K in quasi-static fracturing stage I The stress intensity factor of the crack is greater than the fracture toughness of the rock, and the formula is:

[0096]

[0097] In the formula, K I is the crack extension condition in the quasi-static fracturing stage; a=rr b is the total length of the crack; σ θ2 (r b +x,θ) is (r b The radial stress around the hole in the quasi-static fracturing stage at the position of +x, θ; b is the radius of the deep hole; π is the circumference of a circle; x is the distance between a point on the crack and the starting point of the crack on the hole wall; K I is the fracture toughness of rock, C1, C2, C3 are calculated as follows:

[0098]

[0099] In the formula, z r =log 10 (a / r b ), a=rr b is the total length of the crack, r b is the radius of the deep hole;

[0100] 10) The Gauss-Legendre numerical integration formula is used to convert equation (11) into an equation about r and θ, and the range of crack extension in the quasi-static fracturing stage is obtained and its distribution is plotted in polar coordinates, which is a method for calculating the influence range of carbon dioxide phase change fracturing in deep vertical wells.

[0101] Example 3

[0102] The deep-hole carbon dioxide phase change fracturing of a rock formation with the maximum horizontal stress of σ H =20MPa, the minimum ground stress is σ h =15MPa, the uniaxial tensile strength is measured as σ t =8MPa, the radius of the blast hole is 0.15m. The parameters of the carbon dioxide fracturing tube used include the carbon dioxide fracturing tube rupture pressure P c , diameter of carbon dioxide fracturing tube d c , pressure increase factor n, exponential parameter γ, carbon dioxide gas attenuation coefficient K, etc. are shown in Table 1.

[0103] Table 1 Parameters of carbon dioxide fracturing pipe

[0104]

[0105] The proposed method for calculating the influence range of carbon dioxide phase change fracture in deep holes is used to calculate the influence range of carbon dioxide phase change fracture as follows: Figure 2 As shown. It should be noted that the five-node Gauss-Legendre numerical integration formula is used in step (8). As can be seen from the figure, the initiation zone and crack propagation zone of deep hole carbon dioxide phase change fracturing in this example are both ellipses, with the major axis corresponding to the horizontal minimum ground stress direction and the minor axis corresponding to the horizontal maximum ground stress direction. The major axis diameter of the initiation zone is 0.69m, the minor axis diameter is 0.59m, and the major axis diameter of the crack propagation zone is 5.89m, the minor axis diameter is 4.03m.

[0106] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0107] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft, characterized in that: include: The carbon dioxide phase change fracturing process is divided into two stages: dynamic impact stage and quasi-static fracturing stage. Considering the initial ground stress state and the pressure caused by the carbon dioxide phase change in the two stages, the stress field distribution around the hole in the two stages is calculated respectively. Then, based on the dynamic tensile stress and crack intensity factor, the range of the crack initiation zone and the crack propagation zone are calculated respectively.

2. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 1, characterized in that: The method is the initial ground stress state before the dynamic impact stage, including the method of calculating the initial stress distribution: Taking the center of the deep hole as the origin of the polar coordinates and the direction of the maximum horizontal geostress as the x-axis of the polar coordinates, the initial stress distribution around the hole under the action of horizontal geostress is calculated: Among them, σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; τ rθ0 is the initial shear stress at position (r, θ); σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates.

3. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 1, characterized in that: The specific methods of the dynamic impact stage in this method include: Calculate the impact pressure on the deep hole wall caused by carbon dioxide phase change cracking during the dynamic impact stage; Calculate the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure; According to the impact pressure and dynamic stress distribution, the conditions for crack initiation in the dynamic impact stage are determined; The crack initiation range around the hole in the dynamic impact stage is determined according to the dynamic stress distribution, and the distribution of the crack initiation range around the hole in the dynamic impact stage is plotted in polar coordinates.

4. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 3, characterized in that: The formula for calculating the impact pressure P1 caused by carbon dioxide phase change cracking on the deep hole wall during the dynamic impact stage is: Among them, P1 is the impact pressure caused by carbon dioxide phase change cracking on the deep hole wall during the dynamic impact stage; n is the pressure increase multiple; P c is the rupture pressure of carbon dioxide-induced fracture pipe; d c is the diameter of the carbon dioxide fracturing tube; d b is the diameter of the deep hole; γ is the exponential parameter; The formula for calculating the dynamic stress distribution around the hole caused by the stress wave generated by the impact pressure is: Among them, σ rd , σ θd are the dynamic radial stress and dynamic annular stress caused by the stress wave generated by the impact pressure at a distance r from the center of the deep hole; P1 is the impact pressure caused on the wall of the deep hole during the phase change cracking of carbon dioxide in the dynamic impact stage; rb is the radius of the deep hole; r and θ are the radius and angle of the polar coordinates.

5. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 4, characterized in that: The conditions for judging the cracking in the dynamic impact stage are: Among them, σ θ1 (r, θ) is the total radial stress around the hole during the dynamic impact stage; σ r0 (r, θ), σ θ0 (r, θ) are the initial radial stress and initial hoop stress at the position (r, θ) respectively; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; P1 is the impact pressure on the deep hole wall caused by carbon dioxide phase change fracturing in the dynamic impact stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates; σ t is the uniaxial tensile strength of rock.

6. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 1, characterized in that: The specific methods of the quasi-static fracturing stage in the method include: Calculate the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage; Calculate the quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at the distance from the center of the deep hole; Calculate the radial stress around the hole during the quasi-static fracturing stage; The conditions for determining crack propagation during the quasi-static fracturing stage are that the stress intensity factor of the crack is greater than the fracture toughness of the rock; The formula for the crack extension condition in the static fracturing stage is converted into an equation about the radius and angle of polar coordinates through the Gauss-Legendre numerical integration formula. The range of crack extension in the quasi-static fracturing stage is obtained and its distribution is plotted in polar coordinates, that is, the influence range of carbon dioxide phase change fracturing in deep vertical wells is obtained.

7. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 6, characterized in that: The formula for calculating the quasi-static pressure P2 caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage in this method is: P2=KP c Among them, P2 is the quasi-static pressure caused by carbon dioxide on the deep hole wall during the quasi-static fracturing stage; K is the carbon dioxide gas attenuation coefficient; P c is the carbon dioxide-induced fracture pipe rupture pressure; The quasi-static radial stress and quasi-static hoop stress caused by carbon dioxide phase change cracking in the crack at a distance r from the center of the deep hole are calculated as follows: Among them, σ rs (r), σ θs (r) are the quasi-static radial stress and quasi-static annular stress caused by the quasi-static pressure at a distance r from the center of the deep hole; P2 is the quasi-static pressure caused by carbon dioxide on the wall of the deep hole during the quasi-static fracturing stage; r b is the radius of the deep hole; r, θ are the radius and angle of the polar coordinates.

8. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 7, characterized in that: The formula for calculating the radial stress around the hole in the quasi-static fracturing stage in this method is: Among them, σ θ2 (r, θ) is the radial stress around the hole during the quasi-static fracturing stage; σ θ0 (r, θ) is the initial hoop stress at position (r, θ); σ θs (r) is the quasi-static hoop stress caused by the quasi-static pressure at a distance r from the center of the deep hole; σ H and σ h are the maximum horizontal stress and minimum horizontal stress of the formation respectively; r b is the radius of the deep hole.

9. The method for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft according to claim 8, characterized in that: The conditions for crack propagation in the quasi-static fracturing stage of this method are specifically: The crack propagation condition K in the quasi-static fracturing stage I The stress intensity factor of the crack is greater than the fracture toughness of the rock, and the formula is: Among them, K I is the crack extension condition in the quasi-static fracturing stage; a=rr b is the total length of the crack; σ θ2 (r b +x,θ) is (r b =K is the radial stress around the hole in the quasi-static fracturing stage at the position of (x, θ); x is the distance between a point on the crack and the starting point of the crack on the hole wall; K IC is the fracture toughness of rock, C1, C2, and C3 are coefficients.

10. A system for calculating the impact range of carbon dioxide phase change fracturing in a deep vertical shaft, characterized in that: include: a memory for storing executable computer programs; A processor, for implementing the method for calculating the influence range of carbon dioxide phase change fracturing in a deep vertical well as claimed in any one of claims 1 to 9 when executing an executable computer program stored in a memory.

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