A design method and system for a spiral blade PDC drill bit cutting structure

Abstract

The present invention discloses a design method and system for a spiral blade PDC drill bit cutting structure, the method comprising the following steps: performing a single triaxial compressive strength test on an outcrop or downhole core to obtain rock mechanics parameters; establishing a three-dimensional cutting structure of a PDC drill bit based on Archimedean spirals and the front and rear rows of teeth of a PDC drill bit; establishing a drill bit-rock finite element model based on the rock mechanics parameters and the three-dimensional cutting structure of a PDC drill bit; obtaining a drilling pressure torque time history curve based on the drill bit-rock finite element model; establishing a drill bit cutting structure design scheme based on the drilling pressure torque time history curve; obtaining a spiral blade drill bit cutting structure based on the drill bit cutting structure design scheme. The present invention quantitatively describes the blade helicity and derives the coupling influence mechanism of the helicity and cutting section on the rock breaking efficiency and stability of a PDC drill bit, avoiding high-cost engineering tests, and the proposed design scheme can improve the near-drilling stability while improving the rock breaking efficiency of a PDC drill bit.

Description

Technical Field

[0001] The invention belongs to the technical fields of oil field machinery, oil and gas well construction, and more particularly relates to a design method and system for a spiral blade PDC drill bit cutting structure. Background Art

[0002] PDC drill bits are widely used in the process of shale gas development. In engineering applications, the improvement, development and design of PDC drill bits are mainly based on the cutting structure. The rock breaking efficiency and stability of PDC drill bits are balanced from the perspective of single tooth structure, radial / circumferential tooth arrangement, and tooth material selection based on the engineering use effect. Although the engineering test results are a direct reflection of whether the drill bit improvement design example is effective, the improvement design and manufacturing of PDC drill bits requires a design cycle of 1-2 weeks. Under the influence of complex engineering factors, the cost of trial and error of design examples is high, which leads to a strong reliance on experience when developing and improving drill bits. A relatively simple single tooth / tooth group cutting structure can be used for a series of experimental studies indoors, but there are still few reports on the quantitative study of the influence of multi-parameter coupling design examples including helicity on the rock breaking effect of the entire drill bit. The aforementioned studies on single teeth and tooth groups show that there are significant differences in the rock breaking efficiency or stability of the cutting structure under different cutting section designs. In some engineering cases, the spiral blade design example is considered to reduce the probability of the drill bit whirling motion and improve the drilling stability (Improved Bit Stability Reduces Downhole Harmonics (Vibrations): SPE / IADC Asia Pacific Drilling Technology, 1996 / 09 / 09, Development of Whirl Resistant PDC Bits: SPE Latin America / Caribbean Petroleum Engineering Conference, 1994 / 04 / 27). At present, it is mainly reflected by several design modes such as "straight line-arc-straight line", "straight line-arc-arc" or Archimedean spiral, but the blade helicity is not uniformly defined by a certain design mode, and the design is relatively arbitrary. Therefore, the role of the spiral degree in aggressiveness and stability has not been studied or discussed in series. To address this problem, it is particularly important to propose a design method and system that can quantitatively describe the blade helicity and clarify the degree to which the helicity reduces vibration and improves efficiency under different designed cutting sections. Summary of the invention

[0003] The present invention aims to solve the deficiencies of the prior art and proposes a design method and system for a spiral blade PDC drill bit cutting structure, which provides theoretical support for the design of an efficient and stable spiral blade PDC drill bit.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for designing a spiral blade PDC drill bit cutting structure comprises the following steps:

[0006] Conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanical parameters;

[0007] Based on the Archimedean spiral and the front and rear teeth of the PDC drill bit, a three-dimensional cutting structure of the PDC drill bit is established;

[0008] Based on the rock mechanical parameters and the three-dimensional cutting structure of the PDC drill bit, a drill bit-rock finite element model is established;

[0009] Based on the drill bit-rock finite element model, a time history curve of the bit pressure torque is obtained;

[0010] Based on the drilling pressure torque time history curve, a PDC drill bit cutting structure design scheme is established;

[0011] Based on the PDC drill bit cutting structure design scheme, a spiral blade PDC drill bit cutting structure is obtained.

[0012] Preferably, the rock mechanical parameters include density ρ, elastic modulus E, Poisson's ratio μ, internal friction angle and cohesion c.

[0013] Preferably, the method for establishing the three-dimensional cutting structure of the PDC drill bit is:

[0014] Based on the degree of deviation between the front and rear row teeth and the cutting depth control distance, the cutting section of the bottom of the well is controlled; when the front and rear row teeth are out of track by the degree of equal division of the spacing between the tooth centers of the adjacent front row teeth, the degree of deviation is expressed by the multiple of the equal division of the spacing between the tooth centers of the front row teeth;

[0015] Based on the Archimedean spiral, the circumferential tooth arrangement reference of the spiral blade is controlled;

[0016] The three-dimensional cutting structure of the PDC drill bit is established based on the designed cutting section at the bottom of the well and the circumferential tooth arrangement reference of the spiral blade.

[0017] Preferably, the designed cutting section at the bottom of the well includes the projection or body of the front row teeth, the rear row teeth, the rear row teeth with different tracks, the rear row teeth with the same track, the radial tooth arrangement line of the front row teeth, the radial tooth arrangement line of the rear row teeth and the cutting depth control distance of the front and rear row teeth on the radial tooth arrangement view;

[0018] Preferably, the boundary conditions of the drill bit-rock finite element model are the mechanical rotation speed and the near-drilling rotation speed.

[0019] Preferably, based on the drilling pressure torque time history curve, the method for establishing the PDC drill bit cutting structure design scheme is:

[0020] Performing statistical calculation on the stable cutting section of the WOB torque time history curve to obtain a WOB mean, a torque mean, a WOB standard deviation, and a torque standard deviation;

[0021] Obtaining mechanical specific energy based on the average drilling pressure and the average torque;

[0022] Based on the bit weight standard deviation and the torque standard deviation, obtaining the axial / circumferential vibration amplitude;

[0023] The triaxial compressive strength under the bottom hole liquid column pressure is used as the mechanical specific energy benchmark;

[0024] Based on the mechanical specific energy and the mechanical specific energy reference, obtaining a mechanical specific energy change rate;

[0025] Based on the axial / circumferential vibration amplitude and the mechanical specific energy change rate, the PDC drill bit cutting structure design scheme is obtained.

[0026] Preferably, the design parameters of the PDC drill bit cutting structure design include the degree of front and rear row teeth out of alignment, the front and rear row teeth cutting depth control distance and the polar angle span.

[0027] The present invention also provides a design system for a spiral blade PDC drill bit cutting structure, which is used to implement the design method, and comprises:

[0028] The experimental module is used to conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanics parameters;

[0029] A three-dimensional structure building module is used to build a three-dimensional cutting structure of a PDC drill bit based on the Archimedean spiral and the front and rear teeth of the PDC drill bit;

[0030] A model building module, used to build a drill bit-rock finite element model based on the rock mechanical parameters and the three-dimensional cutting structure of the PDC drill bit;

[0031] A time history curve acquisition module, used for obtaining a time history curve of a bit pressure torque based on the drill bit-rock finite element model;

[0032] A design scheme establishing module, for establishing a PDC drill bit cutting structure design scheme based on the bit pressure torque time history curve;

[0033] The design scheme application module is used to obtain the spiral blade PDC drill bit cutting structure based on the PDC drill bit cutting structure design scheme.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: the design method of the spiral blade PDC drill bit cutting structure provided by the present invention establishes a three-dimensional cutting structure of the PDC drill bit based on the Archimedean spiral and the front and rear rows of teeth of the PDC drill bit, solves the problems of large arbitrariness in the design of blade helicity and insufficient understanding of the influence of blade helicity on rock breaking efficiency and near-drilling vibration characteristics, and establishes a drill bit-rock finite element model based on rock mechanics parameters and the three-dimensional cutting structure of the PDC drill bit; obtains a drilling pressure torque time history curve based on the drill bit-rock finite element model; establishes a PDC drill bit cutting structure design scheme based on the drilling pressure torque time history curve; proposes several high-efficiency and stable spiral PDC drill bit cutting structure reserve design schemes, providing theoretical support for the design of high-efficiency and stable spiral blade PDC drill bits. The present invention quantitatively describes the blade helicity and derives the coupling influence mechanism of helicity and cutting section on the rock breaking efficiency and stability of the PDC drill bit, avoiding high-cost engineering experiments, and the proposed design scheme can improve the near-drilling stability while improving the rock breaking efficiency of the PDC drill bit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A schematic diagram of a design method for a spiral blade PDC drill bit cutting structure provided for an embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the radial tooth arrangement view of the spiral blade PDC drill bit;

[0038] Figure 3 This is the engineering drawing of the 3D model of the spiral blade PDC drill bit;

[0039] Figure 4 It is a schematic diagram of the solution results of the finite element model;

[0040] Figure 5 is the cutting depth control distance ΔL2, polar angle span θ span And the schematic diagram of the effect of the degree of off-track LODT on the mean WOB;

[0041] Figure 6 is the cutting depth control distance ΔL2, polar angle span θ span And the schematic diagram of the effect of the degree of off-track LODT on the mean torque MeanTOB;

[0042] Figure 7 is the cutting depth control distance ΔL2, polar angle span θspan And the schematic diagram of the effect of the degree of off-track LODT on the torque standard deviation SDWOB;

[0043] Figure 8 is the cutting depth control distance ΔL2, polar angle span θ span And the schematic diagram of the effect of the off-track degree LODT on the torque standard deviation SDTOB;

[0044] Fig. 9 is the cutting depth control distance ΔL2, polar angle span θ span Schematic diagram of the effect on the rate of change of mechanical specific energy ΔMSE;

[0045] Fig.10 It is a schematic diagram of the effect of the degree of off-track LODT on the rate of change of mechanical specific energy ΔMSE;

[0046] Fig.11 The lower polar angle span θ is the specific cutting depth control distance ΔL2 span Schematic diagram of the impact on the mean torque value Mean TOB;

[0047] Fig.12 The lower polar angle span θ is the specific cutting depth control distance ΔL2 span Schematic diagram of the effect on torque standard deviation SD TOB;

[0048] Fig.13 The lower polar angle span θ is the specific cutting depth control distance ΔL2 span Schematic diagram of the effect on the rate of change of mechanical specific energy ΔMSE;

[0049] Fig.14 It is a schematic diagram of the cutting structure drawing of the proposed spiral blade PDC drill bit;

[0050] Description of the accompanying drawings: 1-front row teeth; 2-rear row teeth; 3-rear row teeth on different tracks; 4-rear row teeth on the same track; 5-radial tooth layout line of the front row teeth; 6-radial tooth layout line of the rear row teeth; 7-circumferential reference of the tooth layout of the front row teeth; 8-circumferential reference of the tooth layout of the rear row teeth; 9-blade orientation line; 10-dotted line of drill bit diameter. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Embodiment 1

[0054] like Figure 1 As shown, a design method for a spiral blade PDC drill bit cutting structure includes the following steps:

[0055] Conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanical parameters;

[0056] A further embodiment is that the rock mechanical parameters include density ρ, elastic modulus E, Poisson's ratio μ, internal friction angle and cohesion c. The stress-equivalent plastic strain curve in the hardening stage is calculated and obtained according to the following formula;

[0057]

[0058] In the above formula: true —True stress, MPa; σ nom —Nominal stress, MPa; ε nom —nominal strain, dimensionless; ε ln pl —equivalent plastic strain, dimensionless; E—elastic modulus, GPa;

[0059] Based on the Archimedean spiral and the front and rear teeth of the PDC drill bit, a three-dimensional cutting structure of the PDC drill bit is established;

[0060] A further embodiment is that the method for establishing the three-dimensional cutting structure of the PDC drill bit is:

[0061] Based on the degree of deviation between the front and rear row teeth and the cutting depth control distance, the cutting section of the bottom hole is controlled; when the front and rear row teeth are out of track by the degree of equal division of the spacing between the tooth centers of the adjacent front row teeth, the degree of deviation is expressed by the multiple of the equal division of the spacing between the tooth centers of the front row teeth;

[0062] Based on the Archimedean spiral, the circumferential tooth arrangement benchmark of the spiral blade is controlled;

[0063] Specifically, the front and rear row teeth different track level LODT (Level of different track) and the front and rear row teeth cutting depth control distance ΔL2 are used to control the well bottom design cutting section in the radial tooth layout view: Figure 2As shown, the designed cutting section at the bottom of the well mainly includes the projection or body of the front row teeth 1, the rear row teeth 2, the rear row teeth 3 with different tracks, the rear row teeth 4 with the same track, the radial tooth arrangement line 5 of the front row teeth, the radial tooth arrangement line 6 of the rear row teeth and the cutting depth control distance ΔL2 of the front and rear row teeth on the radial tooth arrangement view; when the front and rear row teeth are on different tracks to the extent that the intervals between the tooth centers of the adjacent front row teeth 1 are equally divided, the degree of different tracks LODT is expressed by the multiple of the intervals between the tooth centers of the front row teeth 1; when all the rear row teeth 2 are on the same track with the front row teeth 1, the rear row teeth 2 are called the rear row teeth 4 with the same track, and it is considered that this When the off-track degree LODT is 0, when the rear row teeth 2 are off-track with the front row teeth 1, the rear row teeth 2 are called off-track rear row teeth 3, and the off-track degree LODT thereof varies with a certain span within a certain interval (such as the specific case involved in the present invention: interval [0, 5 / 6], span 1 / 6); the angle between each blade azimuth line 9 and the due east direction is defined as the blade azimuth angle, the front row teeth circumferential reference 7 and the drill bit diameter imaginary line 10 form an intersection point K, a straight line is drawn from the drill bit center O to K, and the angle between the straight line OK and the blade azimuth line is the polar angle span θ span . In the polar angle span θ span The interval is controlled by the Archimedean spiral according to a certain span (such as the specific case of the present invention: the interval [0, 60°], with a span of 12°) according to the following formula based on the Archimedean spiral to control the front row tooth arrangement circumferential reference 7, the control parameter A is shown in Table 1, and the rear row tooth arrangement circumferential reference 8 is obtained by the front row tooth arrangement circumferential reference 7 offset by the offset distance ΔL1 (straight blade ΔL1 = 17 mm, spiral blade ΔL1 = 25 mm, and the offset distance ΔL1 can be adjusted for processing technology). When the back rake angle and the side rake angle are both 0°, one end of each single tooth surface is in "point-to-point" contact with the spiral to ensure that the projection of the contact point of each tooth with the formation in the top view is consistent with the spiral at the beginning of cutting, with a polar angle span θ span = 60° as an example, the three-dimensional model engineering drawing of the spiral blade PDC drill bit is as follows Figure 3 shown.

[0064] r=Aθ span +B (1)

[0065]

[0066] In the above formula, r is the radial distance, mm; A is the radial distance value that increases with each unit angle r of the helix, mm; θ span —polar angle span, °; ​​B—when θ span = 0 when the distance from the starting point to the origin of the polar coordinates, mm, in this embodiment, 0 mm;

[0067] Table 1

[0068]

[0069] The three-dimensional cutting structure of the PDC drill bit is established based on the designed cutting section at the bottom of the well and the circumferential tooth layout benchmark of the spiral blade.

[0070] Based on rock mechanics parameters and the three-dimensional cutting structure of the PDC drill bit, a drill bit-rock finite element model is established;

[0071] A further implementation method is that the boundary conditions of the drill bit-rock finite element model are the mechanical rotation speed ROP and the near-drilling rotation speed RPM.

[0072] Based on the drill bit-rock finite element model, the drilling pressure torque time history curve is obtained;

[0073] The obtained WOB and TOB time history curves have a start-up phase and a stable phase, such as Figure 4 shown.

[0074] Based on the drilling pressure torque time history curve, the PDC drill bit cutting structure design scheme is established;

[0075] A further implementation method is to establish a PDC drill bit cutting structure design scheme based on the bit pressure torque time history curve:

[0076] The stable cutting section of the WOB torque time history curve is statistically calculated to obtain the mean WOB, mean torque, standard deviation SD WOB and standard deviation SD TOB of the WOB;

[0077] Based on the mean WOB and the mean TOB, the mechanical specific energy (MSE) is obtained.

[0078] Based on the standard deviation of bit weight SD WOB and the standard deviation of torque SD TOB, the axial / circumferential vibration amplitude is obtained;

[0079] The triaxial compressive strength TCS under the bottom hole fluid column pressure bore , as a benchmark for mechanical specific energy;

[0080] Based on the mechanical specific energy and the mechanical specific energy benchmark, the mechanical specific energy change rate is obtained. The mechanical specific energy change rate ΔMSE is introduced to evaluate the rock breaking efficiency. When ΔMSE is positive, it means that the PDC drill bit under a certain design feature requires additional energy to break the rock. When ΔMSE is negative, it means that a certain design feature of the PDC drill bit reduces the energy required for rock breaking.

[0081] Based on the axial / circumferential vibration amplitude and the mechanical specific energy change rate ΔMSE, combined with engineering practice, the PDC drill bit cutting structure design scheme is obtained. (The mechanical specific energy change rate ΔMSE is used as the objective function)

[0082] Based on the PDC drill bit cutting structure design scheme, the spiral blade PDC drill bit cutting structure is obtained.

[0083] A further embodiment is that the design parameters of the PDC bit cutting structure design scheme include the front and rear row teeth off-track degree LODT, the front and rear row teeth cutting depth control distance ΔL2 and the polar angle span θ span .

[0084]

[0085]

[0086] In the above formulas, MSE-mechanical specific energy, 10 3 MPa; Mean WOB-mean drilling pressure, kN; RPM-speed per minute, r / min, the present invention takes 140r / min in combination with engineering practice; Mean TOB-mean torque, kNm; A b - Drill area, which can be taken as πD b 2 , mm 2 ;D b - drill bit outer diameter, mm; ROP-mechanical rotation speed, m / h, the present invention takes 11.25m / h in combination with engineering practice; μ b -Drill bit sliding friction coefficient, dimensionless. ΔMSE is the change ratio of mechanical specific energy, %; TCS bore is the triaxial compressive strength when the confining pressure is the bottom hole liquid column pressure, MPa.

[0087] Embodiment 2

[0088] As shown in Table 2 (Table 2 is the recommended design parameters for 215.9mm spiral blade PDC drill bits) and Fig.14 As shown, the present invention provides several sets of spiral blade PDC drill bit cutting structure design schemes and design drawings with mechanical specific energy change rate ΔMSE as the objective function, which are obtained by the method in the above embodiment;

[0089] Table 2

[0090]

[0091] refer to Fig.13 From the calculation results of the mechanical specific energy change rate ΔMSE, it can be seen that when the cutting depth control distance ΔL2 ≥ 1.5mm, the mechanical specific energy change rate ΔMSE is negative, which means that when the cutting depth control distance ΔL2 ≥ 1.5mm, the PDC drill bit reduces the energy required for rock breaking, and the cutting depth control distance ΔL2 ≥ 1.5mm should be selected.

[0092] refer to Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11as well as Fig.12 , considering different cutting depth control distance ΔL2 (ΔL2 ≥ 1.5mm), the polar angle span θ span The influence of the off-track degree LODT on the mean bit weight Mean WOB, mean torque Mean TOB, standard deviation of bit weight SD WOB, standard deviation of torque SD TOB and mechanical specific energy change rate ΔMSE is different.

[0093] Specifically, the degree of off-track LODT = 3 / 6, the cutting depth control distance of the front and rear rows of teeth ΔL2 = 2.5 mm, and the polar angle span θ span =60°, selected when the vibration resistance of the tooth material is superior to that of a certain rock;

[0094] Degree of off-track LODT = 3 / 6, front and rear row tooth cutting depth control distance ΔL2 = 2.0 mm, polar angle span θ span =60°, selected when the vibration resistance or force resistance of the tooth material is superior to that of a certain rock;

[0095] Degree of off-track LODT = 3 / 6, front and rear row tooth cutting depth control distance ΔL2 = 1.5mm, polar angle span θ span =60°, selected when the tooth material resistance is superior to a certain rock;

[0096] Degree of off-track LODT = 3 / 6, front and rear row tooth cutting depth control distance ΔL2 = 2.5mm, polar angle span θ span =48°, selected when the tooth material resistance is superior to that of a certain rock.

[0097] The recommended design parameters of efficient and stable spiral blade PDC drill bits are listed in ascending order with the mechanical specific energy change rate ΔMSE as the objective function, as shown in Table 2. The values ​​of each item in the gray-background cell in each column are the minimum or similarly small in each column. By comparison, the corresponding design scheme is selected in combination with the axial or circumferential resistance and vibration resistance of the cutting tooth material: ① When the vibration resistance of the tooth material is superior to a certain rock, the design schemes numbered 1 and 2 in Table 2 can be selected to weaken the axial / circumferential force of the cutting tooth; ② When the resistance performance of the tooth material is superior to a certain rock, the design schemes numbered 2, 4 or 6 in Table 2 can be selected to weaken the risk of impact damage caused by vibration of the cutting tooth in the axial / circumferential direction;

[0098] According to the above optimization principle, 1, 2, 4, and 6 in Table 2 are mainly used as reserve design schemes. The spiral blade PDC drill bit cutting structure is established with the help of computer 3D-aided modeling and the design drawings are output, such as Fig.14 As shown, it is an example of a high-efficiency and stable spiral blade PDC drill bit cutting structure (drill bit diameter 215.9 mm) obtained by optimizing the design method proposed in the present invention.

[0099] Embodiment 3

[0100] The present invention also provides a design system for a spiral blade PDC drill bit cutting structure, which is used to implement a design method, including:

[0101] The experimental module is used to conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanics parameters;

[0102] A three-dimensional structure building module is used to build a three-dimensional cutting structure of a PDC drill bit based on the Archimedean spiral and the front and rear teeth of the PDC drill bit;

[0103] Model building module, used to build drill bit-rock finite element model based on rock mechanical parameters and PDC drill bit three-dimensional cutting structure;

[0104] A time history curve acquisition module is used to obtain a time history curve of the bit pressure torque based on a drill bit-rock finite element model;

[0105] Design scheme establishment module, used to establish the PDC drill bit cutting structure design scheme based on the drilling pressure torque time history curve;

[0106] The design scheme application module is used to obtain the spiral blade PDC drill bit cutting structure based on the PDC drill bit cutting structure design scheme.

[0107] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A design method for a spiral blade PDC drill bit cutting structure, characterized in that: The following steps are involved: Conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanical parameters; Based on the Archimedean spiral and the front and rear rows of teeth of the PDC drill bit, a three-dimensional cutting structure of the PDC drill bit is established; the method for establishing the three-dimensional cutting structure of the PDC drill bit is: Based on the degree of deviation between the front and rear row teeth and the cutting depth control distance, the cutting section of the bottom of the well is controlled; when the front and rear row teeth are out of track by the degree of equal division of the spacing between the tooth centers of the adjacent front row teeth, the degree of deviation is expressed by the multiple of the equal division of the spacing between the tooth centers of the front row teeth; Based on the Archimedean spiral, the circumferential tooth arrangement reference of the spiral blade is controlled; Based on the designed cutting section at the bottom of the well and the circumferential tooth arrangement reference of the spiral blade, a three-dimensional cutting structure of the PDC drill bit is established; Based on the rock mechanical parameters and the three-dimensional cutting structure of the PDC drill bit, a drill bit-rock finite element model is established; Based on the drill bit-rock finite element model, a time history curve of bit pressure torque is obtained; Based on the drilling pressure torque time history curve, a PDC drill bit cutting structure design scheme is established; Based on the drilling pressure torque time history curve, the method for establishing the PDC drill bit cutting structure design scheme is as follows: Performing statistical calculation on the stable cutting section of the WOB torque time history curve to obtain a WOB mean, a torque mean, a WOB standard deviation, and a torque standard deviation; Obtaining mechanical specific energy based on the average drilling pressure and the average torque; Based on the bit weight standard deviation and the torque standard deviation, obtaining the axial / circumferential vibration amplitude; The triaxial compressive strength under the bottom hole liquid column pressure is used as the mechanical specific energy benchmark; Based on the mechanical specific energy and the mechanical specific energy benchmark, a mechanical specific energy change rate is obtained; the mechanical specific energy change rate is introduced to evaluate rock breaking efficiency, when the mechanical specific energy change rate is positive, it means that the PDC drill bit under a certain design feature requires additional energy to break the rock, and when the mechanical specific energy change rate is negative, it means that the PDC drill bit under a certain design feature reduces the energy required for rock breaking; Based on the axial / circumferential vibration amplitude and the mechanical specific energy change rate, a design scheme of the PDC drill bit cutting structure is obtained; Based on the PDC drill bit cutting structure design scheme, a spiral blade PDC drill bit cutting structure is obtained.

2. The design method of the spiral blade PDC drill bit cutting structure according to claim 1, characterized in that: The rock mechanics parameters include density ρ, elastic modulus E, Poisson's ratio μ, internal friction angle φ and cohesion c.

3. The design method of the spiral blade PDC drill bit cutting structure according to claim 1, characterized in that: The designed cutting section at the bottom of the well includes the projection or body of the front row teeth, the rear row teeth, the rear row teeth on different tracks, the rear row teeth on the same track, the radial tooth arrangement line of the front row teeth, the radial tooth arrangement line of the rear row teeth and the cutting depth control distance of the front and rear row teeth on the radial tooth arrangement view.

4. The design method of the spiral blade PDC drill bit cutting structure according to claim 1, characterized in that: The boundary conditions of the drill bit-rock finite element model are the mechanical rotation speed and the near-drilling rotation speed.

5. The design method of the spiral blade PDC drill bit cutting structure according to claim 1, characterized in that: The design parameters of the PDC drill bit cutting structure design scheme include the degree of front and rear row teeth out of alignment, the front and rear row teeth cutting depth control distance and the polar angle span.

6. A design system for a spiral blade PDC drill bit cutting structure, characterized in that: The design method for implementing any one of claims 1 to 5 comprises: The experimental module is used to conduct uniaxial and triaxial compressive strength tests on outcrops or underground cores to obtain rock mechanics parameters; A three-dimensional structure building module is used to build a three-dimensional cutting structure of a PDC drill bit based on the Archimedean spiral and the front and rear teeth of the PDC drill bit; A model building module, used to build a drill bit-rock finite element model based on the rock mechanical parameters and the three-dimensional cutting structure of the PDC drill bit; A time history curve acquisition module, used for obtaining a time history curve of a bit pressure torque based on the drill bit-rock finite element model; A design scheme establishing module, for establishing a PDC drill bit cutting structure design scheme based on the bit pressure torque time history curve; The design scheme application module is used to obtain the spiral blade PDC drill bit cutting structure based on the PDC drill bit cutting structure design scheme.

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