A fracture flow calculation method and computer-readable storage medium and its application

Abstract

The invention discloses a fracture flow calculation method and a computer-readable storage medium, the method comprising the following steps: S1: collecting fracture parameters, fluid property parameters and pumping parameters of field conditions; S2: assuming that the flow of the upper fracture system is Q1, the flow of the lower fracture system is Q2=Q0-Q1, wherein Q0 is the total flow of the fracture; S3: calculating the flow velocity of each small fracture in the upper and lower fracture systems and the corresponding Reynolds number; S4: calculating the resistance coefficient or flow correction coefficient and water flow nonlinear index of each small fracture according to whether the small fracture is a smooth fracture or a rough fracture; S5: respectively calculating the sum of the head losses corresponding to the upper and lower fracture systems; S6: comparing the sum of the head losses of the two, if the convergence standard is reached, the set Q1 and the corresponding Q2 are the required flow; if the convergence standard is not reached, re-assuming Q 1' , repeat steps S2-S6. The method provided by the present invention has small computational workload, high computational efficiency, and can be applied to various engineering practices.

Description

Technical Field

[0001] The present invention belongs to the technical field of fracture flow distribution calculation, and in particular relates to a fracture flow distribution calculation method and a computer-readable storage medium and applications thereof. Background Art

[0002] The fracture-cave carbonate reservoirs in Tahe Oilfield are mainly composed of large caves, dissolved pores and fractures. Their distribution is controlled by sedimentation, structure, paleo-geomorphology and multi-stage karstification. They are extremely heterogeneous fracture-cave carbonate reservoirs. Their main characteristics include discontinuous spatial distribution of reservoir bodies, large differences in the scale of effective reservoir spaces, and complex contact relationships between internal structures and fractures and caves. The water injected into the well group is mainly advanced along the dominant channel, while the secondary channel has only a small amount of water entering due to diversion by the main channel, which seriously affects the water injection development effect. For this reason, a water drive flow channel adjustment technology is proposed, which is to place the flow regulating particles in the dominant channel with a relatively high diversion flow, reduce the water flow in the dominant channel, and increase the water flow in the secondary channel. Therefore, the calculation of the water diversion directly affects the amount of flow regulating particles injected and determines the effect of flow regulation. Accurately obtain the crack morphology. For cracks with small size and single shape, their diversion capacity can be calculated using fluid mechanics calculation software. However, in engineering practice, underground cracks are large in size and have different crack shapes. Therefore, directly using fluid mechanics calculation software to calculate the diversion capacity will result in low calculation efficiency and inconvenient operation. In addition, the calculation workload for large-scale crack models is also very large, which cannot be well used in engineering practice applications.

[0003] Invention patent application CN110338779A provides a device and method for detecting the shunt flow of ventriculoperitoneal cerebrospinal fluid shunt tubes, which can detect the shunt flow of ventriculoperitoneal cerebrospinal fluid shunt tubes without affecting drainage, provide a basis for doctors' diagnosis and treatment, and timely adjust the pressure of the patient's shunt tube through the detection of the shunt flow, reduce postoperative complications, relieve patient pain, and improve treatment effects. This technology involves a detection device.

[0004] Patent CN106600993B discloses a method for predicting vehicle flow diversion at intersections based on RFID data. It mainly uses machine learning algorithms based on vehicle RFID data to predict vehicle flow diversion at intersections, provide decision-making basis for intelligent control of intelligent traffic lights, and the correlation between the prediction results and the same time period of the previous day, and selects the traffic flow size of the previous day's prediction period and the first five periods of the prediction period.

[0005] Invention patent application CN110417577A describes a mixed data flow split flow peak prediction method, which proposes a delay correlation coefficient model and introduces a sliding time window into the original time difference correlation analysis method, which can more effectively calculate the delay time and delay correlation coefficient. The mixed data flow split flow peak prediction method proposed in this patent introduces the influence of auxiliary split flow on the main split flow based on the results of the original single prediction model, and ultimately improves the final peak prediction result.

[0006] Literature: "Zhao Qiuxiang, Fu Xiang, Sun Zhaohua, et al., "Evaluation of the Impact of the Operation of the Three Gorges Reservoir on the Diversion of the Three Outlets of the Jingjiang River", Journal of the Yangtze River Scientific Research Institute, 2019" established a diversion model for the three outlets of the Jingjiang River, and used the daily measured flow in Zhicheng from 2008 to 2015 and the corresponding restored flow to calculate the diversion flow of the three outlets of the Jingjiang River with and without the influence of the Three Gorges from 2008 to 2015.

[0007] Existing technologies are mainly concentrated in the use of computers. However, in engineering practice, underground cracks are large in size and have different shapes. Therefore, directly using fluid mechanics calculation software to calculate the diversion capacity will result in low calculation efficiency and inconvenient operation. In addition, the calculation workload for large-scale crack models is also very large, which cannot be well used in engineering practice. Summary of the invention

[0008] In view of the above problems, the present invention provides a fracture flow calculation method and a computer-readable storage medium with small computational workload, high computational efficiency and applicability to various engineering practices, which has a positive effect on the development of existing fracture-cavity carbonate reservoirs and provides support for water channeling control in fracture-cavity reservoirs.

[0009] The technical solution of the present invention is as follows:

[0010] A method for calculating fracture flow distribution, characterized in that it comprises the following steps:

[0011] S1: Set the upper crack system flow rate to Q 1, then the split flow of the lower fracture system is Q 2= Q 0- Q 1, Q 0 is the total flow rate of fluid injected into the fracture by the pump;

[0012] S2: Calculate the flow rate of the fluid in each fracture in the upper fracture system and the lower fracture system based on the fracture parameters and fluid property parameters V and the corresponding Reynolds number Re;

[0013] S3: Calculate the resistance coefficient of the crack smoothing according to the Reynolds number Re λ, and / or, calculate the flow correction coefficient of the rough crack according to the crack parameters α and the nonlinearity index of water flow β ;

[0014] S4: According to the drag coefficient λ The total head loss h of the smooth cracks in the upper crack system is calculated by using the crack parameters ws1 , according to the flow correction factor α , nonlinear index of water flow β The total head loss of the rough cracks in the upper crack system is calculated by using the crack parameters h wr1 , and the total head loss of the upper fracture system is obtained h w1 ;

[0015] According to the drag coefficient λ The total head loss of the smooth cracks in the lower crack system is calculated by using the crack parameters h ws2 , according to the flow correction factor α , nonlinear index of water flow β The total head loss of the rough cracks in the lower crack system is calculated by using the crack parameters h wr2 , and the total head loss of the lower fracture system is obtained h w2 ;

[0016] S5: If according to h w1 , h w2 Convergence criteria are met Q 1 and Q The value of 2.

[0017] Q 0 is the total flow rate of the fluid injected into the crack by the pump, which is usually set manually during construction.

[0018] The "cracks" in this article refer to natural cracks in the formation, which are the main characteristics of fracture-vuggy oil reservoirs.

[0019] In carbonate fracture-cave reservoirs, there are relatively complex parallel-series fracture-cave structures. When water is used to drive oil, water often appears first in the wider channels of the fractures. At this time, the smaller branch fractures can be activated by adjusting and blocking them. The upper and lower branch fractures mentioned here are used to represent different fracture structures in fracture-cave reservoirs. The purpose of the flow split is to judge whether the adjustment of the main fracture flow channel can effectively start the flow of oil phase in the fracture during the water drive process. If the flow of oil phase in the fracture reaches a certain flow rate and meets the production requirements, the corresponding production can be carried out. If it is not enough, further flow adjustment construction needs to be carried out. This is also the purpose of the present invention to calculate the flow split of the upper and lower fracture systems.

[0020] The principle of existing fluid mechanics calculation software is to first establish a geometric model of the fracture-cavity structure, a grid model, a mathematical and physical model of the flow in the fracture-cavity (equations such as continuity, conservation of momentum, turbulence, etc.), and solve the large algebraic equations obtained by discretizing the model through corresponding numerical methods (finite volume, finite difference, finite element, etc.). The problem is that the fracture structure of the fracture-cavity reservoir on site is complex and large in size, so the solution time is necessarily long, and there is also a convergence problem. The idea of ​​the present invention is not to use the existing computational fluid dynamics method. First, the flow-pressure drop law of the top of the accumulation body (pipe flow) and the inside of the plugging body (seepage) is obtained through experiments and computational fluid dynamics simulation fitting, and then a hydraulic model of a complex parallel and series pipeline is established. The flow distribution is obtained by substitution, and there is no need to solve a large algebraic equation group, which is more efficient and simple.

[0021] The crack parameters are selected from: crack width W , seam height H , seam length L , absolute roughness Δ, number of cracks;

[0022] The fluid property parameter is selected from: fluid density ρ , dynamic viscosity of the fluid μ , fluid kinematic viscosity ν .

[0023] Fracture parameters can be obtained by inversion based on logging data during drilling. Specifically, fracture width W and fracture height H can be measured by using a sixty-arm logging instrument or by querying the early geological data of the reservoir; fracture length L , Number of cracks n It is obtained by querying the interpretation of reservoir seismic data; the absolute roughness Δ is obtained based on on-site core sampling and indoor tests, which are routine operations in this field.

[0024] Parameters such as fluid density ρ, fluid dynamic viscosity μ, and fluid kinematic viscosity ν can be obtained through rheometer testing. The fluid includes the water phase used for water flooding, and its physical property parameters have relatively mature results that can be used; the physical properties of the formation oil phase can be obtained by using a rheometer under simulated formation conditions. It is a common operation in this field to simulate the underground reservoir environment and test with a rheometer.

[0025] The pumping parameter, i.e., the total flow rate of the fluid injected into the fracture by the pump, is manually controlled during the on-site construction process and is read by the flow meter on the system.

[0026] The early geological data of the reservoir and the interpretation of the seismic data of the reservoir are technical data well known to technicians in the petroleum field. They are internal data unique to a specific reservoir. For relevant oil field units to which the calculation method of the present invention is applicable, the early geological data of the reservoir and the interpretation of the seismic data of the reservoir of the relevant reservoir can be used to obtain relevant parameters, and the calculation method of the present invention can be used to calculate the fracture distribution flow.

[0027] In step S5, according to h w1 、h w2 and convergence criteria Q 1 and Q The value of 2 means: w1 、h w2 If the convergence criterion is met, the Q 1 is the flow rate of the upper fracture system; if h w1 、h w2 If the convergence criteria are not met, reset Q 1 and repeat steps S1-S5 until h w1 、h w2 satisfying the convergence criteria;

[0028] Preferably, the convergence criterion is .

[0029] The inner meaning of the convergence standard used in the present invention is that the change in the water head loss before and after the two steps of iteration is less than one thousandth of itself.

[0030] The reset Q 1 and repeat steps S1-S5 to refer to:

[0031] If h w1 >h w2 ,but Q 1' =0.999 Q 1. Repeat steps S1-S5;

[0032] If h w1 <h w2 ,but Q 1'=1.001 Q 1. Repeat steps S1-S5;

[0033] in Q 1' For reset Q 1.

[0034] In step S2,

[0035] Fluid flow rate QUOTE ,in Q is the flow rate of a crack in the fracture system, W is the width of the crack, H is the crack height;

[0036] The Reynolds number , where ρ is the fluid density, V is the flow velocity of the fluid, W is the crack width, μ is the dynamic viscosity of the fluid, and ν is the kinematic viscosity of the fluid.

[0037] In step S3, the flow pattern is judged according to the Reynolds number and the relative roughness to distinguish between smooth cracks and rough cracks, and the resistance coefficients of smooth cracks with different flow patterns are calculated. λ ;

[0038] Preferably, the calculation of the resistance coefficient of the smooth cracks of different flow states is λ refer to:

[0039] If Re<2000, then: ,

[0040] If 2000≤Re<7000, then: ,

[0041] If 7000≤Re<1×10 5 ,but: ;

[0042] The flow correction coefficient α of rough cracks satisfies the following formula:

[0043]

[0044] The nonlinear index β of water flow in rough fractures satisfies the following formula:

[0045] Where Δ is the absolute roughness and W is the crack width.

[0046] In this article, Fig.17As shown, the “upper fracture system” refers to the set of all fractures 201, 202, 203, 204 above the main fracture 1; the “lower fracture system” refers to the set of all fractures 301, 302, 303, 304 below the main fracture 1; “fracture” and “small fracture” refer to any fracture including the main fracture and the branch fracture. Both the main fracture and the branch fracture are fractures. The purpose of the calculation method of the present invention is to calculate the flow of the fluid when it flows through a fracture in the formation fracture and then flows to another fracture. Usually, the fracture that flows in first is called the main fracture or main fracture, and the fracture that is branched in later is called the branch fracture or small branch fracture. Fig.17 For the sake of illustration and convenience, the end of the main crack 1 is closed and divided into two parallel upper and lower branch crack systems, namely, the upper crack system and the lower crack system. It is well known in fluid mechanics that for a series of crack channels, the flow rate of each crack is equal, that is, the flow rate Q of each crack (small branch crack) 201, 202, 203, or 204 in the upper crack system is the same as the flow rate Q1 of the upper crack system initially set, and the flow rate Q of each crack (small branch crack) 301, 302, 303, or 304 in the lower crack system is consistent with the flow rate Q2 of the lower branch crack system initially set.

[0047] Smooth cracks are a common term in this field, and can also be called smooth cracks. They refer to cracks with a relative roughness of less than 0.0005 and a Reynolds number of less than 10. 5 , cracks that do not affect the flow of fluid in the cracks.

[0048] Rough cracks are a common term in this field, which means that the relative roughness is greater than or equal to 0.0005 and the Reynolds number of the fluid flowing through it is greater than 10. 5 , which will affect the flow pattern of fluid in the cracks.

[0049] Any crack in the "upper crack system", any crack in the "lower crack system", and a single "main crack" without parallel cracks are all cracks.

[0050] In step S4,

[0051] Total head loss of the upper fracture system ;

[0052] Total head loss of the lower fracture system .

[0053] Preferably, the total head loss of the smooth fractures in the upper fracture system h ws1 Satisfy the following formula: , where:

[0054] h fs1is the head loss of a single smooth small crack in the upper crack system;

[0055] n is the number of smooth small cracks in the upper crack system;

[0056] λ si is the resistance coefficient of the ith smooth small crack in the upper crack system;

[0057] L si is the length of the i-th smooth small crack in the upper crack system;

[0058] W si is the width of the i-th smooth small crack in the upper crack system;

[0059] V si is the fluid velocity flowing through the i-th smooth fracture in the upper fracture system;

[0060] g is the acceleration due to gravity;

[0061] Preferably, the total head loss of the smooth fractures in the lower fracture system h ws2 Satisfy the following formula:

[0062] , where:

[0063] h fs2 is the head loss of a single smooth small crack in the lower crack system;

[0064] m Smooth the number of small cracks in the lower crack system;

[0065] λ sj is the resistance coefficient of the jth smooth small crack in the lower crack system;

[0066] L sj is the length of the jth smooth small crack in the lower crack system;

[0067] W sj is the width of the jth smooth small crack in the lower crack system;

[0068] V sj is the fluid flow rate flowing through the jth smooth fracture in the lower fracture system.

[0069] The total head loss h of the rough cracks in the upper crack systemwr1 Satisfy the following formula:

[0070] , where:

[0071] h fr1 is the head loss of a single rough small crack in the upper crack system;

[0072] x is the number of rough small cracks in the upper crack system;

[0073] L ri is the length of the i-th rough small crack in the upper crack system;

[0074] Q ri is the flow rate of the i-th rough small crack in the upper crack system;

[0075] ν is the fluid kinematic viscosity;

[0076] g is the acceleration due to gravity;

[0077] W ri is the width of the i-th rough small crack in the upper crack system;

[0078] H ri is the height of the i-th rough small crack in the upper crack system;

[0079] Preferably, the total head loss of the rough fractures in the lower fracture system h wr2 Satisfy the following formula:

[0080] , where:

[0081] h fr2 is the head loss of a single rough small crack in the lower crack system;

[0082] y is the number of rough small cracks in the lower crack system;

[0083] L rj is the length of the jth rough small crack in the upper crack system;

[0084] Q rj is the flow rate of the jth rough small crack in the upper crack system;

[0085] W rjis the width of the jth rough small crack in the upper crack system;

[0086] H rj is the height of the jth rough small crack in the upper crack system.

[0087] A computer-readable storage medium stores a computer program thereon, wherein the computer program implements the fracture flow distribution calculation method when executed by a processor.

[0088] The aforementioned fracture flow rate calculation method and / or the aforementioned computer-readable storage medium are used in oil reservoir development and oil reservoir water channeling control.

[0089] A method for calculating fracture flow distribution comprises the following steps:

[0090] S1: Collect fracture parameters, fluid property parameters and pumping parameters of field conditions, wherein the fracture parameters include fracture length, fracture width, fracture height and fracture relative roughness, the fluid property parameters include fluid density and fluid dynamic viscosity, and the pumping parameters include the total flow rate of the fluid injected into the fracture.

[0091] S2: In actual formations, the expansion of cracks is that a first-level crack is divided into two second-level cracks, and then a second-level crack is divided into two third-level cracks, and so on. Therefore, the formation cracks can be divided into two upper and lower crack systems starting from the initial two cracks. The upper and lower crack systems are respectively composed of multiple small cracks with different lengths, widths, and heights. Assume that the flow rate of the upper crack system is Q 1, then the flow rate of the lower fracture system is Q 2= Q 0- Q 1, where Q 0 is the total flow rate of fluid injected into the fracture by the pump.

[0092] S3: Calculate the flow velocity of each small crack in the upper and lower crack systems and the corresponding Reynolds number:

[0093] (1)

[0094] Where:

[0095] V i is the fluid velocity flowing through the i-th fracture in the upper fracture system, m / s;

[0096] Q i is the flow rate of the ith small crack in the upper crack system, m 3 / s;

[0097] W i is the width of the ith small crack in the upper crack system, m;

[0098] H i is the height of the ith small crack in the upper crack system, m;

[0099] (2)

[0100] Where:

[0101] V j is the fluid velocity flowing through the jth fracture in the lower fracture system, m / s;

[0102] Q j is the flow rate of the jth small crack in the lower crack system, m 3 / s;

[0103] W j is the width of the jth small crack in the lower crack system, m;

[0104] H j is the height of the jth small crack in the lower crack system, m;

[0105] The Reynolds number calculation method is:

[0106] (3)

[0107] Where:

[0108] Re is the flow Reynolds number, dimensionless;

[0109] ρ is the fluid density, kg / m 3 ;

[0110] V is the average speed, m / s;

[0111] W is the crack width, m;

[0112] μ is the dynamic viscosity of the fluid, Pa·s;

[0113] ν is the fluid kinematic viscosity, m 2 / s.

[0114] S4: Based on the crack parameters collected in step S1, determine whether the crack is a smooth crack or a rough crack, wherein when the relative roughness of the crack is less than 0.0005, the crack is considered a smooth crack; when the relative roughness of the crack is greater than or equal to 0.0005, the crack is considered a rough crack. Calculate the resistance coefficient or flow correction coefficient and water flow nonlinear index of each small crack according to whether the small crack is a smooth crack or a rough crack:

[0115] When the small cracks are smooth cracks, the resistance coefficient of each small crack is calculated according to the Reynolds number. The resistance coefficient calculation method is:

[0116] If Re<2000, then:

[0117] (4)

[0118] If 2000≤Re<7000, then:

[0119] (5)

[0120] If 7000≤Re<1×10 5 ,but:

[0121] (6)

[0122] Where:

[0123] λ is the drag coefficient, dimensionless;

[0124] Re is the flow Reynolds number, dimensionless.

[0125] When the small cracks are rough cracks, the flow correction coefficient and water flow nonlinear index of each small crack are calculated according to the relative roughness. The calculation method of the flow correction coefficient and water flow nonlinear index is:

[0126] (7)

[0127] (8)

[0128] Where:

[0129] α is the rough fracture flow correction factor, dimensionless;

[0130] β is the nonlinear index of fracture flow, dimensionless;

[0131] Δ is the absolute roughness, m;

[0132] W is the crack width, m.

[0133] Δ / W is the relative roughness, dimensionless.

[0134] S5: Calculate the total head loss corresponding to the upper and lower fracture systems respectively. The specific method is:

[0135] (9)

[0136] (10)

[0137] Where:

[0138] h w1 is the total head loss of the upper fracture system, m;

[0139] h ws1 is the total head loss of smooth small cracks in the upper crack system, m;

[0140] h wr1 is the total head loss of rough small cracks in the upper crack system, m;

[0141] h w2 is the total head loss of the lower fracture system, m;

[0142] h ws2 is the total head loss of smooth small cracks in the lower crack system, m;

[0143] h wr2 is the total head loss of rough small cracks in the lower fracture system, m.

[0144] The calculation method for the total head loss of smooth small cracks in formula (9) and formula (10) is:

[0145] (11)

[0146] Where:

[0147] h fs1 is the head loss of a single smooth small crack in the upper crack system, m;

[0148] n is the number of smooth small cracks in the upper crack system, dimensionless;

[0149] λ si is the resistance coefficient of the ith smooth small crack in the upper crack system, dimensionless;

[0150] Lsi is the length of the i-th smooth small crack in the upper crack system, m;

[0151] W si is the width of the ith smooth small crack in the upper crack system, m;

[0152] V si is the fluid velocity flowing through the i-th smooth fracture in the upper fracture system, m / s;

[0153] g is the acceleration due to gravity, m / s 2 ;

[0154] (12)

[0155] Where:

[0156] h fs2 is the head loss of a single smooth small crack in the lower crack system, m;

[0157] m is the number of smooth small cracks in the lower crack system, dimensionless;

[0158] λ sj is the resistance coefficient of the jth smooth small crack in the lower crack system, dimensionless;

[0159] L sj is the length of the jth smooth small crack in the lower crack system, m;

[0160] W sj is the width of the jth smooth small crack in the lower crack system, m;

[0161] V sj is the fluid velocity flowing through the jth smooth fracture in the lower fracture system, m / s.

[0162] The calculation method for the total head loss of rough small cracks in formula (9) and formula (10) is:

[0163] (13)

[0164] Where:

[0165] h fr1 is the head loss of a single rough small crack in the upper crack system, m;

[0166] xis the number of rough small cracks in the upper crack system, dimensionless;

[0167] L ri is the length of the i-th rough small crack in the upper crack system, m;

[0168] Q ri is the flow rate of the ith rough small crack in the upper crack system, m 3 / s;

[0169] ν is the fluid kinematic viscosity, m 2 / s;

[0170] g is the acceleration due to gravity, m / s 2 ;

[0171] W ri is the width of the ith rough small crack in the upper crack system, m;

[0172] H ri is the height of the ith rough small crack in the upper crack system, m;

[0173] (14)

[0174] Where:

[0175] h fr2 is the head loss of a single rough small crack in the lower crack system, m;

[0176] y is the number of rough small cracks in the lower crack system, dimensionless;

[0177] L rj is the length of the jth rough small crack in the upper crack system, m;

[0178] Q rj is the flow rate of the jth rough small crack in the upper crack system, m 3 / s;

[0179] W rj is the width of the jth rough small crack in the upper crack system, m;

[0180] H rj is the height of the jth rough small crack in the upper crack system, m.

[0181] S6: Compare the sum of the head losses of the upper fracture system with the sum of the head losses of the lower fracture system and determine the Q 1 and Q 2, the convergence criterion is ;

[0182] If the convergence criterion is reached, the set Q 1 is the required flow distribution of the upper fracture system, Q 2 is the required flow distribution of the lower fracture system;

[0183] If the convergence criterion is not met, re-assume Q 1', if h w1 >h w2 ,but Q 1'=0.999 Q 1. Repeat steps S2-S6; if h w1 < h w2 ,but Q 1'=1.001 Q 1. Repeat steps S2-S6.

[0184] The relationship between the drag coefficient and the Reynolds number in step S4 is obtained through numerical simulation and linear regression, specifically:

[0185] The most common single fracture geometry model with different fracture widths in the actual fracturing formation is used to carry out the flow field distribution in the single fracture under different velocity conditions. By extracting the numerical simulation results, the relationship between the resistance coefficient applicable to various formation fracture widths and the Reynolds number of the fluid flowing in the fracture is studied.

[0186] According to the definition of fluid mechanics, the drag coefficient The calculation formula is:

[0187] (15)

[0188] Where: Δ p is the pressure drop, Pa;

[0189] In the simulation process, the flow field under different working conditions is simulated to extract the pressure drop at the inlet and outlet, and then the resistance coefficient is calculated using formula (15): , and then use formula (3) to calculate the single-slit Reynolds number Re under this condition, so that the resistance coefficient can be fitted And the corresponding Reynolds number Re value.

[0190] The calculation conditions for fracture flow using formation water are shown in Table 26:

[0191] Table 26 Working conditions and corresponding Reynolds numbers for clean water calculation (×10 3 )

[0192]

[0193] It can be seen from Table 26 that for a total of 15 conditions with a speed ranging from 0.05 m / s to 5 m / s, the Reynolds number corresponding to the 8 mm crack width increases from 400 to 40,000, the Reynolds number corresponding to the 6 mm crack width increases from 300 to 30,000, the Reynolds number corresponding to the 4 mm crack increases from 200 to 20,000, and the Reynolds number corresponding to the 2 mm crack width increases from 100 to 10,000.

[0194] The pressure drop and resistance coefficient of cracks with different widths under different flow rate conditions are shown in Table 10:

[0195] Table 10 Pressure drop and resistance coefficient values ​​for different slit widths (pressure drop unit: Pa)

[0196]

[0197] It can be seen from Table 10 that as the crack width decreases or the fluid velocity increases, the pressure drop value increases rapidly.

[0198] like Figure 1 As shown in the figure, the pressure drop increases linearly in the initial stage with the speed change, and the pressure drop changes nonlinearly when the speed increases further. At the same time, as the slit width decreases, the pressure drop also increases rapidly, but the relationship is relatively complex and there is a mutation phenomenon.

[0199] like Figure 2 As shown in the figure, the change of the resistance coefficient under each slot width condition has a typical feature, which is to decrease rapidly to reach a minimum value, then rise, and then decrease further, but the turning point is different with different slot widths. Basically, the speed increases with the decrease of the slot width.

[0200] According to formula (3), the flow velocity conditions at different crack widths in Table 10 are converted into Reynolds numbers. The resistance coefficients of cracks with different widths under different Reynolds number conditions are shown in Table 11:

[0201] Table 11 Calculation results of drag coefficient under different Reynolds number conditions

[0202]

[0203] It can be seen from Table 11 that due to the use of a unified inlet velocity, the Reynolds numbers are not the same for different slot widths, and the Reynolds number set calculated for small slot widths is generally smaller than that for large slot widths. Therefore, the drag coefficient value for small Reynolds numbers is basically obtained from small slot width conditions, while the drag coefficient value for large Reynolds numbers is basically obtained from large slot width conditions, and the two overlap more under medium Reynolds number conditions. From the calculation results of different slot widths but the same Reynolds number, it can be seen that the drag coefficient values ​​are basically equal, which proves that the drag coefficient depends on the joint influence of factors such as slot width and speed, that is, the influence of Reynolds number.

[0204] The Reynolds number under each working condition is calculated and divided into different intervals according to the Reynolds number, and then the resistance coefficient corresponding to different Reynolds numbers can be obtained.

[0205] When Re<2000, the fluid flow state is laminar flow, and the Reynolds number and resistance coefficient fitting curve are as follows: Figure 3 As shown in the figure, the relationship between the drag coefficient and the Reynolds number at this time is obtained by fitting the curve in the figure (4).

[0206] When 2000≤Re<7000, it is the first hydraulic smooth zone of turbulence, which belongs to the transition zone from laminar flow to turbulent flow. The fitting curve of Reynolds number and resistance coefficient is as follows: Figure 4 As shown in the figure, the relationship between the drag coefficient and the Reynolds number at this time is obtained by fitting the curve in the figure (5).

[0207] When 7000≤Re<1×10 5 When , it is the second hydraulic smooth zone of turbulence, which belongs to the stable turbulence zone. The fitting curve of Reynolds number and resistance coefficient is as follows: Figure 5 As shown in the figure, the relationship between the drag coefficient and the Reynolds number at this time is obtained by fitting the curve in the figure (6).

[0208] Re≥1×10 5 The situation rarely occurs under actual engineering application conditions, but it can be fitted using the same method to obtain the corresponding relationship between the drag coefficient and the Reynolds number.

[0209] The relationship between the flow correction coefficient and the water flow nonlinear index and the roughness in step S4 is obtained through numerical simulation and linear regression, specifically:

[0210] Since the resistance coefficient along the path is a function of the Reynolds number Re and relative roughness (Δ / w), and is not solely dependent on the roughness, simulation analysis is carried out on the most commonly used working conditions with different Reynolds numbers and different roughnesses in actual working conditions to study the relationship between the roughness applicable to various working conditions and the flow correction coefficient and the water flow nonlinear index.

[0211] When the speed is 1m / s and the Reynolds number is 8000, the relationship between the relative roughness and the pressure drop is shown in Table 12. The drag coefficient values ​​along the corresponding conditions are calculated according to the Darcy formula, as shown in the third and sixth rows of Table 12:

[0212] Table 12 Relationship between relative roughness and pressure drop at speed 1m / s

[0213]

[0214] It can be seen from Table 12 that when the relative roughness is less than 0.005, the pressure drop is the same, indicating that the roughness has no effect on the result; when the relative roughness is greater than 0.005, the pressure drop increases with the increase of roughness, which is consistent with the common sense of pipeline head loss.

[0215] When the speed is 2m / s and the Reynolds number is 16000, the relationship between the relative roughness and the pressure drop is shown in Table 13. The drag coefficient values ​​along the corresponding conditions are calculated according to the Darcy formula, as shown in the third and sixth rows of Table 13:

[0216] Table 13 Relationship between relative roughness and pressure drop at speed 2m / s

[0217]

[0218] It can be seen from Table 13 that when the relative roughness is less than 0.002, the pressure drop is the same, indicating that the roughness has no effect on the result; when the relative roughness is greater than 0.002, the pressure drop increases with the increase of roughness, which is consistent with the common sense of pipeline head loss.

[0219] When the speed is 4m / s and the Reynolds number is 32000, the relationship between the relative roughness and the pressure drop is shown in Table 14. The drag coefficient values ​​along the corresponding conditions are calculated according to the Darcy formula, as shown in the third and sixth rows of Table 14:

[0220] Table 14 Relationship between relative roughness and pressure drop at speed 4m / s

[0221]

[0222] It can be seen from Table 14 that when the relative roughness is less than 0.001, the pressure drop is the same, indicating that the roughness has no effect on the result; when the relative roughness is greater than 0.001, the pressure drop increases with the increase of roughness, which is consistent with the common sense of pipeline head loss.

[0223] When the speed is 6m / s and the Reynolds number is 48000, the relationship between the relative roughness and the pressure drop is shown in Table 15. The drag coefficient values ​​along the corresponding conditions are calculated according to the Darcy formula, as shown in the third and sixth rows of Table 15:

[0224] Table 15 Relationship between relative roughness and pressure drop at speed 6m / s

[0225]

[0226] It can be seen from Table 15 that when the relative roughness is less than 0.001, the pressure drop is the same, indicating that the roughness has no effect on the result; when the relative roughness is greater than 0.001, the pressure drop increases with the increase of roughness, which is consistent with the common sense of pipeline head loss.

[0227] According to the classical empirical formula of flow-pressure drop relationship of rough fractures, it is assumed that the flow rate and hydraulic gradient have the following relationship:

[0228] (16)

[0229] Where:

[0230] Q q is the crack flow rate, m 3 / s;

[0231] H is the crack height, m;

[0232] J =Δ P / ( ρgL ) is the hydraulic gradient, dimensionless;

[0233] The slit width is 0.008m, the slit length is 0.5m, and the flow rate is 0.008m 3 / s, 0.016m 3 / s, 0.032m 3 / s, 0.048m 3 / s and 0.064m 3 / s, and the relative roughness is 0.0005, 0.001, 0.002, 0.005, 0.01, 0.015, 0.02, 0.03, 0.04, 0.05 and 0.06 respectively for fitting analysis.

[0234] When the relative roughness is 0.0005, the flow rate in the crack is obtained. Q Hydraulic gradient with fracture plane J As shown in Table 16:

[0235] Table 16 Relative roughness is 0.0005 Q , J value

[0236]

[0237] Table 16 Corresponding flow rate QThe relationship curve between the hydraulic gradient J of the fracture plane is as follows: Figure 6 As shown, according to Figure 6 The curve equation given is combined with equation (16) to obtain β =0.563, α =0.075234.

[0238] When the relative roughness is 0.001, the flow rate in the crack is obtained. Q Hydraulic gradient with fracture plane J As shown in Table 17:

[0239] Table 17 Relative roughness is 0.001 Q , J value

[0240]

[0241] The relationship curve between the flow rate Q and the hydraulic gradient J of the fracture plane corresponding to Table 17 is as follows Figure 7 As shown, according to Figure 7 The curve equation given is combined with equation (16) to obtain β=0.5621 and α=0.075.

[0242] When the relative roughness is 0.002, the flow rate in the crack is obtained. Q Hydraulic gradient with fracture plane J As shown in Table 18:

[0243] Table 18 Relative roughness is 0.002 Q , J value

[0244]

[0245] The relationship curve between the flow rate Q and the hydraulic gradient J of the fracture plane corresponding to Table 18 is as follows Figure 8 As shown, according to Figure 8 The curve equation given is combined with equation (16) to obtain β=0.5501 and α=0.073594.

[0246] When the relative roughness is 0.005, the flow rate Q in the crack and the hydraulic gradient J on the crack plane are shown in Table 19:

[0247] Table 19 Relative roughness is 0.005 Q , J value

[0248]

[0249] Table 19 corresponding flow rate Q The relationship curve between the hydraulic gradient J of the fracture plane is as follows: Fig. 9As shown, according to Fig. 9 The curve equation given is combined with equation (16) to obtain β =0.5132, α =0.067734.

[0250] When the relative roughness is 0.01, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 20:

[0251] Table 20 Relative roughness is 0.01 Q , J value

[0252]

[0253] Table 20 corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.10 As shown, according to Fig.10 The curve equation given is combined with equation (16) to obtain β=0.4856 and α=0.061172.

[0254] When the relative roughness is 0.02, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 21:

[0255] Table 21 Relative roughness is 0.02 Q , J value

[0256]

[0257] Table 21 Corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.11 As shown, according to Fig.11 The curve equation given is combined with equation (16) to obtain β =0.4701, α =0.053672.

[0258] When the relative roughness is 0.03, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 22:

[0259] Table 22 Relative roughness is 0.03 Q , J value

[0260]

[0261] Table 22 Corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.12 As shown, according to Fig.12 The curve equation given is combined with equation (16) to obtain β =0.4781, α =0.049688.

[0262] When the relative roughness is 0.04, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 23:

[0263] Table 23 Relative roughness is 0.04 Q , J value

[0264]

[0265] Table 23 Corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.13 As shown, according to Fig.13 The curve equation given is combined with equation (16) to obtain β =0.484, α =0.046875.

[0266] When the relative roughness is 0.05, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 24:

[0267] Table 24 Relative roughness is 0.05 Q , J value

[0268]

[0269] Table 24 corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.14 As shown, according to Fig.14 The curve equation given is combined with equation (16) to obtain β =0.4891, α =0.044531.

[0270] When the relative roughness is 0.06, the flow rate in the crack is obtained Q Hydraulic gradient with fracture plane J As shown in Table 25:

[0271] Table 25 Relative roughness is 0.06 Q , J value

[0272]

[0273] Table 25 corresponding flow rate Q Hydraulic gradient with fracture plane J The relationship curve is as follows Fig.15 As shown, according to Fig.15 The curve equation given is combined with equation (16) to obtain β =0.493, α =0.042891.

[0274] According to the different roughness conditions β and α Value, make a relationship curve with relative roughness as shown Fig.16 As shown, combined Fig.16 Fitting with polynomials Fig.16 middle β , α Curve, we can get the formula (7) and (8) α and β Relationship with roughness.

[0275] On the other hand, the present invention also protects a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the computing method when executed by a processor.

[0276] Compared with the prior art, the present invention has the following advantages:

[0277] 1. The present invention has small computational workload, high computational efficiency, and is applicable to various engineering practices.

[0278] 2. By considering the crack system as a combination of multiple small cracks, the head loss caused by each small crack is calculated, and then the total head loss caused by the crack system is calculated, the result is more accurate.

[0279] 3. When the crack is a smooth crack, the crack width is small, the Reynolds number of the flow in the crack is small, the fluid in the crack is in a laminar state or a hydraulically smooth state, and the wall roughness will not have an effect at this time. The present invention uses the Reynolds number to obtain the resistance coefficient based on the fitted relationship between the Reynolds number and the resistance coefficient, so that the calculation workload is small and the efficiency is high.

[0280] 4. When the crack is a rough crack, the fluid in the crack is in a mixed friction and hydraulic roughness state, and the wall roughness will affect the flow in the crack. The present invention uses the roughness to obtain the rough crack flow correction coefficient and the crack water flow nonlinear index based on the relationship between the roughness, the rough crack flow correction coefficient and the crack water flow nonlinear index obtained by fitting, and then uses the head loss calculation formula to obtain the head loss by deforming the empirical formula of the flow pressure drop relationship of the rough crack, so that the calculation workload is small and the efficiency is high.

[0281] The present invention is mainly suitable for water injection and water drive of carbonate fracture-cavity oil reservoirs to improve the recovery rate. The reserves of carbonate oil and gas fields in the world account for 50% of the total reserves and 60% of the total production, and the application prospect is broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0282] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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.

[0283] Figure 1 The pressure drop changes with speed for different slit widths;

[0284] Figure 2 The variation of drag coefficient with speed for different slot widths;

[0285] Figure 3 It is the fitting curve of Reynolds number and drag coefficient in laminar flow region;

[0286] Figure 4 It is the fitting curve of Reynolds number and resistance coefficient in the first zone of hydraulic smoothing;

[0287] Figure 5 It is the fitting curve of Reynolds number and resistance coefficient in the second zone of hydraulic smoothing;

[0288] Figure 6 Flow rate when relative roughness is 0.0005 Q Hydraulic gradient with fracture plane J relationship;

[0289] Figure 7 Flow rate when relative roughness is 0.001 Q Hydraulic gradient with fracture plane J relationship;

[0290] Figure 8 Flow rate when relative roughness is 0.002 Q Hydraulic gradient with fracture plane J relationship;

[0291] Fig. 9 Flow rate when relative roughness is 0.005 Q Hydraulic gradient with fracture plane J relationship;

[0292] Fig.10 Flow rate when relative roughness is 0.01 Q Hydraulic gradient with fracture plane J relationship;

[0293] Fig.11 Flow rate when relative roughness is 0.02 Q Hydraulic gradient with fracture plane J relationship;

[0294] Fig.12 Flow rate when relative roughness is 0.03 Q Hydraulic gradient with fracture plane J relationship;

[0295] Fig.13 Flow rate when relative roughness is 0.04 Q Hydraulic gradient with fracture plane J relationship;

[0296] Fig.14 Flow rate when relative roughness is 0.05 Q Hydraulic gradient with fracture plane J relationship;

[0297] Fig.15 Flow rate when relative roughness is 0.06 Q Hydraulic gradient with fracture plane J relationship;

[0298] Fig.16 is β and α Relationship curve with relative roughness;

[0299] Fig.17 This is a top view schematic diagram of the fracture structure in Example 1. This figure simplifies the original fracture structure of the fracture-cave oil reservoir. The fractures in the actual fracture cave have various tortuous changes, and this figure is simplified. The marks in the figure are listed as follows: 1-main fracture, 2-upper fracture system, 201-the first small fracture in the upper fracture system, 202-the second small fracture in the upper fracture system, 203-the third small fracture in the upper fracture system, 204-the fourth small fracture in the upper fracture system, 3-lower fracture system, 301-the first small fracture in the lower fracture system, 302-the second small fracture in the lower fracture system, 303-the third small fracture in the lower fracture system, 304-the fourth small fracture in the lower fracture system. DETAILED DESCRIPTION

[0300] The details of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0301] Example 1

[0302] A method for calculating fracture flow distribution comprises the following steps:

[0303] S1: Collect the fracture parameters, fluid property parameters and pumping parameters of the field conditions as shown in Table 1. The fracture structure diagram is as shown in Fig.17 As shown:

[0304] Table 1 Fracture parameters, fluid property parameters and pumping parameters of field conditions

[0305]

[0306] S2: Assume that the flow rate of the upper fracture system is Q 1=0.5 Q 0=5m 3 / s, then the flow rate of the lower fracture system is Q 2= Q 0- Q 1=0.5 Q 0=5m 3 / s.

[0307] S3: The flow velocity of each small crack and the corresponding Reynolds number are calculated according to formula (1), formula (2) and formula (3) as shown in Table 2:

[0308] Table 2 Flow velocity of each small crack and the corresponding Reynolds number

[0309]

[0310] S4: According to the relative roughness of each small crack in the upper crack system and the lower crack system collected in Table 1, all small cracks are judged to be smooth cracks, and the resistance coefficient of each small crack is calculated according to the Reynolds number. According to the value of the Reynolds number in Table 2, the corresponding formula (4) or formula (5) or formula (6) is selected to calculate the resistance coefficient. The calculation results are shown in Table 3:

[0311] Table 3 Resistance coefficient of each small crack

[0312]

[0313] S5: According to equations (9) to (14), calculate the total head loss h corresponding to the upper and lower fracture systems respectively. w1 =8.77m,h w2 =13.38m.

[0314] S6: Compare the sum of the head losses of the upper fracture system with the sum of the head losses of the lower fracture system and determine the Q 1 and Q 2, the convergence criterion is ,at this time The convergence criterion is not met, and h w1 <h w2 , re-assume Q 1'=1.001 Q 1. Repeat steps S2-S6; finally get Q 1=6.094m 3 / s, the diversion ratio is 60.94%, Q 2=3.906m 3 / s, and the diversion ratio is 39.06%.

[0315] Example 2

[0316] A method for calculating fracture flow distribution comprises the following steps:

[0317] S1: Collect the fracture parameters, fluid property parameters and pumping parameters of the field conditions as shown in Table 4:

[0318] Table 4 Fracture parameters, fluid property parameters and pumping parameters of field conditions

[0319]

[0320] S2: Assume that the flow rate of the upper fracture system is Q 1=0.5 Q 0=6m 3 / s, then the flow rate of the lower fracture system is Q 2= Q 0- Q 1=0.5 Q 0=6m 3 / s.

[0321] S3: The flow velocity of each small crack and the corresponding Reynolds number are calculated according to formula (1), formula (2) and formula (3) as shown in Table 5:

[0322] Table 5 Flow velocity of each small crack and the corresponding Reynolds number

[0323]

[0324] S4: According to the relative roughness of each small crack in the upper crack system and the lower crack system collected in Table 4, the relative roughness is greater than 0.0005. The flow correction coefficient and water flow nonlinear index of each small crack are calculated based on the relative roughness. The flow correction coefficient and water flow nonlinear index are calculated based on the roughness and crack width in Table 4, (7) and (8). The calculation results are shown in Table 6:

[0325] Table 6 Flow correction coefficient and water flow nonlinear index of each small crack

[0326]

[0327] S5: Calculate the total head loss corresponding to the upper and lower fracture systems according to equations (9) to (14) h w1 =10.38m, h w2 =25.52m.

[0328] S6: Compare the sum of the head losses of the upper fracture system with the sum of the head losses of the lower fracture system and determine the Q 1 and Q 2, the convergence criterion is ,at this time The convergence criteria are not met, and h w1 < h w2 , re-assume Q 1'=1.001 Q 1. Repeat steps S2-S6; finally get Q 1=7.34m 3 / s, the diversion ratio is 61.22%, Q 2=4.66m 3 / s, and the diversion ratio is 38.78%.

[0329] Example 3

[0330] S1: Collect the fracture parameters, fluid property parameters and pumping parameters of the field conditions as shown in Table 7:

[0331] Table 7 Fracture parameters, fluid property parameters and pumping parameters of field conditions

[0332]

[0333] S2: Assume that the flow rate of the upper fracture system is Q 1=0.5 Q 0=4m 3 / s, then the flow rate of the lower fracture system is Q 2=Q 0 -Q 1=0.5 Q 0=4m 3 / s.

[0334] S3: The flow velocity of each small crack and the corresponding Reynolds number are calculated according to formula (1), formula (2) and formula (3) as shown in Table 8:

[0335] Table 8 Flow velocity of small cracks and the corresponding Reynolds number

[0336]

[0337] S4: Compare the relative roughness of each small crack in the upper crack system and the lower crack system collected in Table 7 with 0.0005 to determine whether all small cracks are rough cracks or smooth cracks. The judgment results are shown in Table 9. Among them, for smooth cracks, the resistance coefficient of each small crack is calculated according to the Reynolds number. Specifically, the corresponding formula (4) or formula (5) or formula (6) is selected according to the value of the Reynolds number in Table 5 to calculate the resistance coefficient; for rough cracks, the flow correction coefficient and water flow nonlinear index of each small crack are calculated according to the relative roughness. Specifically, the flow correction coefficient and water flow nonlinear index are calculated according to the roughness and crack width in Table 4, (7) and formula (8). The calculation results are shown in Table 9:

[0338] Table 9 Resistance coefficient of each small crack or flow velocity of the crack and the corresponding Reynolds number

[0339]

[0340] S5: According to equations (9) to (14), calculate the total head loss h corresponding to the upper and lower fracture systems respectively. w1 =29.072m,h w2 =13.996m.

[0341] S6: Compare the sum of the head losses of the upper fracture system with the sum of the head losses of the lower fracture system and determine the Q 1 and Q 2, the convergence criterion is ,at this time The convergence criterion is not met, and h w1 >h w2 , re-assume Q 1'=0.999 Q 1. Repeat steps S2-S6; finally get Q 1=3.83m 3 / s, the diversion ratio is 47.93%, Q 2=4.16m 3 / s, and the diversion ratio is 52.07%.

[0342] Embodiment 4: Computer-readable storage medium of the present invention

[0343] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the fracture flow distribution calculation method provided in any one of embodiments 1-3 is implemented.

[0344] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for calculating fracture flow distribution, characterized in that: The following steps are involved: S1: Set the upper crack system flow rate to Q 1, then the split flow of the lower fracture system is Q 2= Q 0- Q 1, Q 0 is the total flow rate of fluid injected into the fracture by the pump; S2: Calculate the flow rate of the fluid in each fracture in the upper fracture system and the lower fracture system based on the fracture parameters and fluid property parameters V and the corresponding Reynolds number Re; S3: Calculate the resistance coefficient of the crack smoothing according to the Reynolds number Re λ , and / or, calculate the flow correction factor of the rough crack according to the crack parameters α and the nonlinearity index of water flow β ; S4: According to the drag coefficient λ The total head loss h of the smooth cracks in the upper crack system is calculated by using the crack parameters ws1 , according to the flow correction factor α , nonlinear index of water flow β The total head loss of the rough cracks in the upper crack system is calculated by using the crack parameters h wr1 , and the total head loss of the upper fracture system is obtained h w1 ; According to the drag coefficient λ The total head loss of the smooth cracks in the lower crack system is calculated by using the crack parameters h ws2 , according to the flow correction factor α , nonlinear index of water flow β The total head loss of the rough cracks in the lower crack system is calculated by using the crack parameters h wr2 , and the total head loss of the lower fracture system is obtained h w2 ; S5: According to h w1 , h w2 Convergence criteria are met Q 1 and Q The value of 2; According to h w1 、h w2 and convergence criteria Q 1 and Q The value of 2 means: w1 、h w2 If the convergence criterion is met, the Q 1 is the flow rate of the upper fracture system; if h w1 、h w2 If the convergence criteria are not met, reset Q 1 and repeat steps S1-S5 until h w1 、h w2 The convergence criterion is met.

2. A method for calculating fracture flow distribution according to claim 1, characterized in that: The crack parameters include: crack width W , seam height H , seam length L , absolute roughness Δ and number of cracks; The fluid property parameters include: fluid density ρ , dynamic viscosity of the fluid μ and fluid kinematic viscosity ν .

3. A fracture flow calculation method according to claim 1, characterized in that: In step S5, according to h w1 、h w2 and convergence criteria Q 1 and Q The value of 2 means: w1 、h w2 If the convergence criterion is met, the Q 1 is the flow rate of the upper fracture system; if h w1 、h w2 If the convergence criteria are not met, reset Q 1 and repeat steps S1-S5 until h w1 、h w2 satisfying the convergence criteria; Preferably, the convergence criterion is .

4. A method for calculating fracture flow distribution according to claim 3, characterized in that: The reset Q 1 and repeat steps S1-S5 to refer to: If h w1 >h w2 ,but Q 1' =0.999 Q 1. Repeat steps S1-S5; If h w1 <h w2 ,but Q 1' =1.001 Q 1. Repeat steps S1-S5; in Q 1' For reset Q 1.

5. A fracture flow calculation method according to claim 1, characterized in that: In step S2, Fluid flow rate ,in Q is the flow rate of a crack in the fracture system, W is the width of the crack, H is the crack height; The Reynolds number , where ρ is the fluid density, V is the flow velocity of the fluid, W is the crack width, μ is the dynamic viscosity of the fluid, and ν is the kinematic viscosity of the fluid.

6. A fracture flow calculation method according to claim 1, characterized in that: In step S3, the flow pattern is judged according to the Reynolds number and the relative roughness to distinguish between smooth cracks and rough cracks, and the resistance coefficients of smooth cracks with different flow patterns are calculated. λ ; Preferably, the calculation of the resistance coefficient of the smooth cracks of different flow states is λ refer to: If Re<2000, then: , If 2000≤Re<7000, then: , If 7000≤Re<1×10 5 ,but: ; The flow correction coefficient α of rough cracks satisfies the following formula: The nonlinear index β of water flow in rough fractures satisfies the following formula: Where Δ is the absolute roughness and W is the crack width.

7. A fracture flow calculation method according to claim 1, characterized in that: In step S4, Total head loss of the upper fracture system ; The total head loss of the lower fracture system ; Preferably, the total head loss of the smooth fractures in the upper fracture system h ws1 Satisfy the following formula: , where: h fs1 is the head loss of a single smooth small crack in the upper crack system; n is the number of smooth small cracks in the upper crack system; λ si is the resistance coefficient of the ith smooth small crack in the upper crack system; L si is the length of the i-th smooth small crack in the upper crack system; W si is the width of the i-th smooth small crack in the upper crack system; V si is the fluid velocity flowing through the i-th smooth fracture in the upper fracture system; g is the acceleration due to gravity; Preferably, the total head loss of the smooth fractures in the lower fracture system h ws2 Satisfy the following formula: , where: h fs2 is the head loss of a single smooth small crack in the lower crack system; m Smooth the number of small cracks in the lower crack system; λ sj is the resistance coefficient of the jth smooth small crack in the lower crack system; L sj is the length of the jth smooth small crack in the lower crack system; W sj is the width of the jth smooth small crack in the lower crack system; V sj is the fluid flow rate flowing through the jth smooth fracture in the lower fracture system.

8. A fracture flow calculation method according to claim 1, characterized in that: The total head loss h of the rough cracks in the upper crack system wr1 Satisfy the following formula: , where: h fr1 is the head loss of a single rough small crack in the upper crack system; x is the number of rough small cracks in the upper crack system; L ri is the length of the i-th rough small crack in the upper crack system; Q ri is the flow rate of the i-th rough small crack in the upper crack system; ν is the fluid kinematic viscosity; g is the acceleration due to gravity; W ri is the width of the i-th rough small crack in the upper crack system; H ri is the height of the i-th rough small crack in the upper crack system; Preferably, the total head loss of the rough fractures in the lower fracture system h wr2 Satisfy the following formula: , where: h fr2 is the head loss of a single rough small crack in the lower crack system; y is the number of rough small cracks in the lower crack system; L rj is the length of the jth rough small crack in the upper crack system; Q rj is the flow rate of the jth rough small crack in the upper crack system; W rj is the width of the jth rough small crack in the upper crack system; H rj is the height of the jth rough small crack in the upper crack system.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a fracture flow distribution calculation method according to any one of claims 1 to 8 is implemented.

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