A shale oil reservoir yield-increasing cost-reducing fracturing optimization design method

Abstract

The present application belongs to the technical field of oil and natural gas development, and particularly relates to a shale oil reservoir yield increasing and cost reducing fracturing optimization design method. The present application obtains the fracture spacing, single-stage ground liquid volume and well soaking time range by adopting high-density fine cutting and fracture forming, pre-pressing water supplementing formation energy and oil displacement agent accelerating imbibition replacement; obtains the perforation cluster number, single cluster hole number, single hole flow, plugging agent addition and temporary plugging series parameters by adopting soluble ball seat hard packer, limited flow perforation dense fracture and temporary plugging diversion soft sub-cluster; determines the economic optimal range of key engineering modification parameters by combining field big data statistical regression, single well EUR comprehensive measurement and economic index sensitivity analysis; selects the horizontal section sweet spot by establishing horizontal section reservoir segmentation and grading evaluation standard; and solves the shale oil reservoir scale benefit development problem through the steps of target block targeted shale oil reservoir yield increasing and cost reducing fracturing optimization design.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and natural gas development, and particularly relates to a shale oil reservoir yield-increasing and cost-reducing fracturing optimization design method. BACKGROUND

[0002] The horizontal well volume fracturing technology is the core technology for realizing yield increase of unconventional resources such as shale oil in North America. By learning from the successful experience of foreign volume reconstruction, and based on the characteristics of shale oil in China, the reservoir exploration and field test are carried out, the horizontal well subdivision cutting volume fracturing technology is innovatively formed, and good yield increase effect is achieved. However, since 2020, the sharp drop of international oil price has brought great impact on the scale benefit development of shale oil, and shale oil development faces technical problems such as yield increase, efficiency increase and cost reduction. It is very difficult to realize the scale benefit development of shale oil reservoirs with low original formation pressure coefficient, low rock brittleness index and low natural productivity. Therefore, it is particularly important to form a fracturing optimization design method that can guide the creation of a new mode of shale oil benefit development around such shale oil reservoirs.

[0003] For shale oil reservoirs with low original formation pressure coefficient, low rock brittleness index and low natural productivity, in order to achieve the purpose of supplementing formation energy, improving fracture control degree, reducing production decline and improving recovery degree, various means can be used for fracturing optimization design, including optimizing fracturing construction parameters, predicting fracture propagation trajectory and evaluating reservoir pressureability. At present, the fracturing optimization design methods for shale oil reservoirs mainly include the following:

[0004] (1) Yang Zhaozhong et al. (A horizontal well multi-cutting fracturing fracture propagation prediction and design parameter optimization method, Patent No. 202110822145.X) uses collected formation parameters, construction parameters and completion parameters to establish a horizontal well multi-cutting fracturing multi-fracture extension pseudo-three-dimensional fluid-solid full coupling model, realizes accurate prediction of fracture propagation trajectory and accurate calculation of fracture geometric parameters, and finally achieves the purpose of optimizing fracturing design parameters and increasing single well production, but does not propose a targeted fracturing optimization design method for large platform benefit development.

[0005] (2) Lu Cong et al. (A tight oil and gas reservoir hydraulic fracturing optimization design method based on pressureability evaluation, Patent No. 202010124893.6) uses basic geological parameters of reservoir fracturing interval to calculate reservoir pressureability index, and optimizes perforation position, adjusts fracturing fluid viscosity and proppant density according to the index, so as to ensure the formation of complex fracture network by hydraulic fracturing, and at the same time realize the effective placement of proppant in the fracture, but ignores the influence of fracturing construction parameters on the final productivity.

[0006] (3) Lei Q, et al. (Lei Q, Weng D, Guan B, Mu L, Xu Y, Wang Z, Guo Y, Li S. Tight oil reservoir reconstruction method based on fracture-controlled fracturing optimization design[J]. Oil Exploration and Development, 2020, 47(03): 592-599) considered the characteristics of stress interference caused by multiple fracture propagation, matrix wettability reversal caused by large-scale fracturing fluid entering the reservoir, and reservoir property changes, and proposed a tight oil reservoir reconstruction method based on fracture-controlled fracturing optimization design. By optimizing the fracture spacing, cluster number in the section, construction scale, and fracture propagation state, the maximum utilization of the reserves in the well control unit is realized. However, the reconstruction idea of this method is mainly to optimize the fracturing parameters and improve the fracture-controlled reserves, ignoring the optimization of platform technology and economy.

[0007] The above three methods do not consider the contradiction between yield increase and cost reduction under the condition of low-cost development strategy, and do not form a shale oil reservoir fracturing optimization design method based on comprehensive consideration of yield increase concept, main process and parameter optimization. SUMMARY

[0008] The present application provides a shale oil reservoir yield increase and cost reduction fracturing optimization design method, which aims to provide a fracturing design method that not only solves the problem of low initial formation pressure coefficient, low rock brittleness index, and low natural productivity of shale oil reservoirs, but also balances the contradiction between yield increase and cost reduction under the new situation of shale oil development.

[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0010] A shale oil reservoir yield increase and cost reduction fracturing optimization design method, comprising the following steps,

[0011] Step 1: Combine high-density fine cutting to form fractures, pre-fracturing water to supplement formation energy, and use nano oil displacement viscous slick water fracturing fluid as oil displacement agent to speed up imbibition displacement, optimize fracture spacing, single-section fluid volume, and well soaking time range;

[0012] Step 2: Use full-soluble metal ball seat for long horizontal well fine cutting volume fracturing, use limited flow perforation dense fracture and temporary plugging diversion soft cluster, optimize horizontal well perforation cluster number, single cluster hole number, single hole flow rate, plugging agent addition, and temporary plugging series parameters;

[0013] Step 3: Combine field big data statistical regression, single well EUR comprehensive measurement, and economic indicator sensitivity analysis to establish an economic evaluation system of key engineering reconstruction parameters and determine the economic optimal range of each key engineering reconstruction parameter;

[0014] Step 4: Use large well cluster multi-layer system three-dimensional well arrangement, establish horizontal section reservoir segmentation and grading evaluation standard, select the horizontal section sweet spot of each horizontal well according to the reservoir segmentation and grading evaluation results, and carry out large-scale segmented multi-cluster volume fracturing reconstruction respectively;

[0015] Step five: According to the results of step one to step five, the target block is designed for shale oil reservoir fracturing optimization.

[0016] The specific method of high-density subdivision cutting fracture spacing range in step one is as follows,

[0017] First step: By inputting the reservoir boundary conditions, ground stress, elastic modulus, Poisson's ratio, permeability, porosity, fracturing fluid viscosity, filtration coefficient, construction displacement, pumping time, fracture location parameters into the three-dimensional finite element analysis software 3D-FEM, the shale oil reservoir horizontal well multi-cluster fracture propagation map under different fracture spacing is obtained, and the fracture spacing forming the complex fracture network with the largest contact area with the reservoir is selected;

[0018] Second step: The effective seepage distance of matrix is calculated by using the following low-permeability reservoir one-dimensional linear seepage pressure distribution equation (1), and the fracture spacing that makes the fluid seepage distance in the matrix shortest is selected;

[0019]

[0020] In the formula,

[0021] P - formation pressure, MPa;

[0022] Pe - original formation pressure, MPa;

[0023] Pw - bottom hole pressure, MPa;

[0024] Pc - casing pressure, MPa;

[0025] G - threshold pressure gradient, MPa / m;

[0026] s - skin factor, pollution coefficient caused by the change of near-wellbore permeability;

[0027] x - distance from the heel of the horizontal wellbore, m;

[0028] L - horizontal well length, m;

[0029] Third step: A multi-cluster fracturing complex fracture network model is established by using Mangrove fracturing software to simulate the relationship between different fracture spacing and production when the horizontal section length is constant, and the fracture spacing with the largest cumulative production is selected;

[0030] Fourth step: The intersection of the fracture spacing in the first step to the third step is used as the fracture spacing range for high-density subdivision cutting fracture.

[0031] The specific method for obtaining the single-stage liquid volume range of the pre-pressing clean water to supplement the formation energy in the step one is as follows,

[0032] First step: obtaining and analyzing the microseismic monitoring results, establishing a single-stage liquid volume and fracture zone length relationship chart, and selecting the single-stage liquid volume that meets the fracture forming demand under the corresponding well spacing condition according to the full fracture coverage principle;

[0033] Second step: according to the single-stage liquid volume obtained in the first step, using the relationship formula (2) between the liquid volume and the formation pressure in the reservoir engineering, calculating the single-stage liquid volume that needs to be increased when the formation pressure coefficient is increased to the preset value under the corresponding well spacing condition, and selecting the increment of the single-stage liquid volume that can supplement the formation energy;

[0034] ΔV=C t ·V·ΔP (2)

[0035] In the formula,

[0036] V——fracture volume-liquid volume, m 3 ;

[0037] Ct——integrated compressibility, MPa -1 ;

[0038] ΔV——liquid volume that needs to be increased, m 3 ;

[0039] ΔP——increased formation pressure, MPa.

[0040] Third step: superimposing the single-stage liquid volume obtained in the first step and the increment of the single-stage liquid volume obtained in the second step, that is, obtaining the liquid volume value of the pre-pressing clean water to supplement the formation energy.

[0041] The specific method for obtaining the well shut-in time range of the oil displacement agent to accelerate the imbibition replacement in the step one is as follows,

[0042] First step: using nuclear magnetic resonance and imaging system to perform horizontal well core static imbibition experiment, establishing imbibition speed and time relationship chart and imbibition recovery and time relationship chart, and selecting the well shut-in time when the imbibition effect reaches equilibrium;

[0043] Second step: using mathematical analysis software Matlab to simulate the imbibition process of the fracturing fluid in the matrix, establishing a well shut-in time and invasion distance relationship chart, and selecting the well shut-in time when the fracturing fluid invasion distance reaches equilibrium;

[0044] Third step: taking the intersection of the well shut-in times obtained in the first step and the second step as the well shut-in time range of the nano oil displacement variable viscosity slick water fracturing fluid to accelerate the oil-water displacement efficiency.

[0045] The specific method of the step two of densely perforating the limited flow perforation adopts the following steps,

[0046] First step: obtaining construction discharge, perforation hole number, perforation hole diameter and perforation hole and near wellbore region friction parameters, and inputting the parameters into Fracpro PT fracturing software to calculate hole friction;

[0047] Second step: drawing hole friction calculation chart under different discharge and hole number;

[0048] Third step: according to the stress difference range between clusters, using the limited flow to overcome the stress difference between clusters, screening the single cluster number, single cluster hole number and single hole flow value.

[0049] The specific method of the step two of temporary plugging and steering soft cluster adopts the following steps,

[0050] First step: obtaining field temporary plugging construction data and temporary plugging and steering physical model test data;

[0051] Second step: according to the data obtained in the first step, establishing temporary plugging agent addition amount and temporary plugging pressure increase value distribution chart;

[0052] Third step: according to the temporary plugging agent addition amount and temporary plugging pressure increase value distribution chart obtained in the second step, taking the average plugging agent dosage corresponding to the temporary plugging pressure increase value ≥10 MPa as the single-stage temporary plugging agent addition amount;

[0053] Fourth step: using numerical simulation software Meyer to simulate the fracture morphology after fracturing under different cluster numbers and different stage numbers of temporary plugging, and selecting the single-stage temporary plugging stage number.

[0054] The detailed process of establishing the economic evaluation system of key engineering modification parameters in combination with field big data statistics regression, single well EUR comprehensive measurement and economic indicator sensitivity analysis is as follows,

[0055] First step: collecting the engineering modification parameters of shale oil horizontal wells in the field, including the number of stages, the number of clusters, the fracture density, the downhole liquid volume, the sand volume, the liquid injection intensity, the sand injection intensity, the discharge and the production data of 100-meter horizontal section half-year cumulative oil production, establishing the relationship chart of each engineering modification parameter and 100-meter horizontal section half-year cumulative oil production, analyzing the positive correlation of each engineering modification parameter and 100-meter horizontal section half-year cumulative oil production, and selecting the top three engineering modification parameters with positive correlation as the key engineering modification parameters;

[0056] Second step: according to the key engineering modification parameters obtained in the first step, measuring the single well economic effective recoverable reserves under different key engineering modification parameters, and establishing the relationship chart of each key engineering modification parameter and single well economic effective recoverable reserves;

[0057] Third step: according to the relationship between the key engineering modification parameters obtained in the second step and the economic and effective recoverable reserves of single well, an economic recommendation chart of different key engineering modification parameters is established, and the region corresponding to the technical and economic balance point of each parameter is selected, that is, the interval range of the economic maximization of each parameter.

[0058] The specific method for selecting the horizontal section sweet spot in the step four of establishing the horizontal section reservoir segmentation grading evaluation standard is as follows,

[0059] First step: obtaining the well logging interpretation data of the horizontal well full well section, including depth, vertical depth, acoustic time difference, density, gamma, shale content, effective porosity and oil saturation;

[0060] Second step: inputting the parameters obtained in the first step into the Fracpro PT fracturing software to perform rock mechanics parameter calculation, and obtaining the minimum horizontal principal stress and brittleness index parameters;

[0061] Third step: based on the effective porosity and oil saturation of the reservoir quality parameters in the first step and the minimum horizontal principal stress and brittleness index of the engineering quality parameters in the second step, a horizontal section reservoir segmentation grading evaluation standard is established.

[0062] Fourth step: according to the horizontal section reservoir segmentation grading evaluation standard, the horizontal section sweet spot of the target well is selected.

[0063] The horizontal section reservoir segmentation grading evaluation standard is that the reservoir quality is divided into three levels of I, II and III according to the effective porosity, oil saturation, minimum horizontal principal stress and brittleness index, the engineering quality is divided into three levels of A, B and C, when the reservoir quality is I and the engineering quality is A, it indicates that the comprehensive quality is good, when the reservoir quality is III or the engineering quality is C, it indicates that the comprehensive quality is poor, and the rest indicates that the comprehensive quality is medium.

[0064] Beneficial effects:

[0065] The present application obtains the fracture spacing, single-stage ground liquid volume and well shut-in time range by adopting high-density fine cutting to form a fracture + water supplement before pressure to supplement the formation energy + oil displacement agent to accelerate imbibition replacement, obtains the perforation cluster number, single-cluster hole number, single-hole flow, blocking agent addition amount and temporary blocking series parameters by adopting soluble ball seat hard packer + limited flow perforation dense fracture + temporary blocking soft sub-cluster, and determines the economic optimal range of key engineering modification parameters by combining field big data statistical regression + single well EUR comprehensive measurement + economic index sensitivity analysis; the horizontal section sweet spot is selected by establishing the horizontal section reservoir segmentation grading evaluation standard; and the target block is subjected to the steps of shale oil reservoir production increase and cost reduction fracturing optimization design, so that the problems of low original formation pressure coefficient, low rock brittleness index and low natural productivity of the shale oil reservoir are solved, the contradiction between production increase and cost reduction under the new situation of shale oil development is balanced, and the present application has wide applicability.

[0066] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, and can be implemented according to the content of the specification, as follows. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0068] Figure 1 The flow chart of the present application.

[0069] Figure 2 The cumulative oil production change graph under different fracture spacings when the horizontal section length is 80m in the specific embodiment of the present application.

[0070] Figure 3 The relationship graph between the single-section ground liquid volume and the fracture zone length in the specific embodiment of the present application.

[0071] Figure 4 The relationship graph between the imbibition speed and the imbibition time in the specific embodiment of the present application.

[0072] Figure 5 The relationship graph between the imbibition recovery rate and the imbibition time in the specific embodiment of the present application.

[0073] Figure 6 The relationship graph between the well shut-in time and the invasion distance in the specific embodiment of the present application.

[0074] Figure 7 The hole friction calculation graph under different discharge capacities and hole numbers in the specific embodiment of the present application.

[0075] Figure 8 The temporary plugging agent addition amount and temporary plugging pressure increase value distribution graph in the specific embodiment of the present application.

[0076] Figure 9 The fracture density and single-well EUR relationship graph in the specific embodiment of the present application.

[0077] Figure 10 The liquid inlet intensity and single-well EUR relationship graph in the specific embodiment of the present application.

[0078] Figure 11 The sanding intensity and single-well EUR relationship graph in the specific embodiment of the present application.

[0079] Figure 12The fracture density economic recommendation chart in the specific embodiment of the present application.

[0080] Figure 13 The liquid inlet intensity economic recommendation chart in the specific embodiment of the present application.

[0081] Figure 14 The sanding intensity economic recommendation chart in the specific embodiment of the present application.

[0082] Figure 15 The three-dimensional development schematic diagram of the shale oil reservoir in the specific embodiment of the present application. DETAILED DESCRIPTION

[0083] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0084] Embodiment one:

[0085] According to Figure 1 The shale oil reservoir yield improvement and cost reduction fracturing optimization design method shown in FIG. 1 comprises the following steps,

[0086] Step one: combining high-density subdivision cutting fracturing, pre-pressing water supplementing formation energy and using nano oil displacement viscous slick water fracturing fluid as oil displacement agent to accelerate imbibition displacement, optimizing fracture spacing, single-stage ground liquid volume, and well soaking time range;

[0087] Step two: using full-soluble metal ball seat to perform long horizontal well subdivision cutting volume fracturing, using limited flow perforation dense fracture and temporary plugging diversion soft sub-cluster, optimizing horizontal well perforation cluster number, single cluster hole number, single hole flow, plugging agent addition amount, and temporary plugging series parameters;

[0088] Step three: combining field big data statistical regression, single well EUR comprehensive measurement, and economic index sensitivity analysis, establishing an economic evaluation system of key engineering modification parameters, and determining the economic optimal range of each key engineering modification parameter;

[0089] Step four: using large well cluster multi-layer system three-dimensional well arrangement, establishing horizontal section reservoir segmentation grading evaluation standard, selecting the horizontal section sweet spot of each horizontal well according to the reservoir segmentation grading evaluation result, and respectively developing large-scale segmented multi-cluster volume fracturing modification;

[0090] Step five: according to the results obtained from steps one to five, performing targeted shale oil reservoir yield improvement and cost reduction fracturing optimization design for the target block.

[0091] The technical scheme of the present application not only solves the problem of low shale oil reservoir yield caused by low original formation pressure coefficient, low rock brittleness index and low natural productivity, but also balances the contradiction between yield increase and cost reduction under the new situation of shale oil development, and has wide application.

[0092] EUR is the abbreviation of Estimated Ultimate Recovery, and the Chinese meaning of EUR is estimated ultimate recovery.

[0093] Example two:

[0094] According to Figure 1 The shale oil reservoir yield increase and cost reduction fracturing optimization design method shown in FIG. 2 is different from example one in that the specific method of high-density subdivision cutting to form a fracture spacing range in step one is as follows,

[0095] Step one: input the reservoir boundary conditions, ground stress, elastic modulus, Poisson's ratio, permeability, porosity, fracturing fluid viscosity, filtration coefficient, construction displacement, pump-in time, and fracture location parameters into the three-dimensional finite element analysis software 3D-FEM to obtain a shale oil reservoir horizontal well multi-cluster fracture propagation graph under different fracture spacings, and select the fracture spacing that forms the complex fracture network with the largest contact area with the reservoir through the fracture propagation graph;

[0096] Step two: calculate the effective matrix flow distance and select the fracture spacing that makes the fluid flow distance in the matrix shortest by using the following low-permeability reservoir one-dimensional linear seepage pressure distribution equation (1);

[0097]

[0098] In the formula:

[0099] P is the formation pressure, MPa;

[0100] Pe is the original formation pressure, MPa;

[0101] Pw is the bottom hole pressure, MPa;

[0102] Pc is the casing pressure, MPa;

[0103] G is the threshold pressure gradient, MPa / m;

[0104] s is the skin factor, which is the pollution factor caused by the change of the near-wellbore permeability;

[0105] x is the distance from the heel of the horizontal wellbore, m;

[0106] L is the horizontal well length, m;

[0107] Step 3: Use Mangrove fracturing software to establish a multi-cluster fracturing complex fracture network model, simulate the relationship between different fracture spacing and production when the horizontal section length is constant, and select the fracture spacing with the maximum cumulative production;

[0108] Step 4: Use the intersection of the crack spacing in steps 1 to 3 as the crack spacing range for high-density subdivision cutting and cracking.

[0109] The present invention utilizes complex fracture expansion, reservoir engineering, numerical simulation and other methods to comprehensively optimize the fracture spacing with the goal of "maximum contact area, shortest seepage distance and highest cumulative production".

[0110] The nano-displacement viscous slickwater fracturing fluid used in this embodiment uses the nano-displacement viscous slickwater fracturing fluid patented US201815956617. This nano-displacement viscous slickwater fracturing fluid targets the imbibition displacement mechanism of shale reservoirs and offers advantages such as variable viscosity sand-carrying, nano-displacement, online mixing, and circulating fluid preparation. It enhances the efficiency of micro- and nano-pore imbibition displacement, facilitates fluid displacement in dense shale reservoirs, and represents a key advancement in the shale oil horizontal well volume fracturing 2.0 process.

[0111] High-density subdivision cutting and fracking is an optimized fracture placement method for horizontal well volume fracturing. By densely arranging fractures through multiple clusters of perforations, high-density subdivision cutting is achieved in the horizontal section, thereby increasing the extent of the fracture network. To achieve optimal fracture network reach, this embodiment optimizes the optimal fracture spacing range for high-density subdivision cutting and fracking, achieving full, simultaneous production of the reservoir.

[0112] Both 3D-FEM and Mangrove, the three-dimensional finite element analysis software, are currently available. 3D-FEM integrates multiple data-intensive fracture modeling capabilities, enabling analysis and simulation of the initiation and propagation of natural fractures and three-dimensional composite fractures in well-stratified reservoirs.

[0113] Example 3:

[0114] according to Figure 1 The method for optimizing the design of hydraulic fracturing to increase production and reduce costs in a shale oil reservoir shown in the embodiment differs from that in the first embodiment in that the specific method for replenishing the formation energy with fresh water before fracturing to obtain the range of the liquid volume in a single stage is as follows:

[0115] Step 1: Obtain and analyze microseismic monitoring results, establish a relationship chart between single-segment fluid volume and fracture zone length, and select the single-segment fluid volume that meets the fracture creation requirements under the corresponding well spacing conditions based on the principle of full fracture coverage.

[0116] Second step: according to the single section ground liquid volume obtained in the first step, the increased single section ground liquid volume required when the formation pressure coefficient is increased to the preset value under the corresponding well spacing condition is calculated by using the relationship formula (2) between the ground liquid volume and the formation pressure in the oil reservoir engineering, and the increment of the single section ground liquid volume capable of supplementing the formation energy is selected;

[0117] Delta V = C t V * Delta P (2)

[0118] In the formula,

[0119] V - fracture reconstruction volume - ground liquid volume, m 3 ;

[0120] Ct - comprehensive compression coefficient, MPa -1 ;

[0121] Delta V - increased liquid volume, m 3 ;

[0122] Delta P - increased formation pressure, MPa.

[0123] Third step: the single section ground liquid volume obtained in the first step and the increment of the single section ground liquid volume obtained in the second step are superimposed, that is, the ground liquid volume value of the clean water before pressure is obtained.

[0124] The present application uses microseismic monitoring result analysis and oil reservoir engineering method, and takes "increasing fracture reconstruction volume and supplementing deep formation energy" as the target, and comprehensively optimizes the ground liquid volume range.

[0125] The microseismic monitoring technology in the embodiment is a fracture monitoring means in the prior art.

[0126] Example four:

[0127] According to Figure 1 The shale oil reservoir yield increasing and cost reducing fracturing optimization design method shown in the figure is different from example one, and the specific method for obtaining the shut-in time range by accelerating the displacement of the oil displacement agent in step one is as follows,

[0128] First step: the horizontal well core static imbibition experiment is carried out by using the nuclear magnetic resonance and imaging system, the imbibition speed-time relationship chart and the imbibition recovery-time relationship chart are established, and the shut-in time when the imbibition effect reaches equilibrium is selected;

[0129] Second step: the imbibition process of the fracturing fluid in the matrix is simulated by using the mathematical analysis software Matlab, the shut-in time-invasion distance relationship chart is established, and the shut-in time when the invasion distance of the fracturing fluid reaches equilibrium is selected;

[0130] Third step: take the intersection of the well killing time obtained in the first step and the second step as the well killing time range for using the nano oil displacement viscous slick water fracturing fluid to accelerate the oil-water displacement efficiency.

[0131] The present application uses high-pressure imbibition displacement experiment, numerical simulation analysis, and mine field big data analysis methods to optimize the shale oil reservoir post-fracturing well killing time range for the purpose of accelerating the oil-water displacement efficiency.

[0132] Example five:

[0133] According to Figure 1 A shale oil reservoir yield improvement and cost reduction fracturing optimization design method is shown in Figure 1, which is different from example one in that the specific method of step two is as follows,

[0134] First step: obtain the construction discharge, the number of perforation holes, the diameter of the perforation holes, and the perforation hole and near wellbore region friction parameters, and input the parameters into the Fracpro PT fracturing software to calculate the hole friction;

[0135] Second step: draw a hole friction calculation chart under different discharge and hole number;

[0136] Third step: according to the stress difference range between clusters, use flow limiting to overcome the stress difference between clusters, and select the number of single-stage clusters, the number of single-cluster holes, and the single-hole flow value.

[0137] The present application uses the hydraulic fracturing design analysis software Fracpro PT to calculate the hole friction, draw a hole friction calculation chart under different discharge and hole number, use flow limiting to overcome the stress difference between clusters, and optimize the number of single-stage clusters, the number of single-cluster holes, and the single-hole flow, which effectively improves the fracture initiation efficiency under the segmented multi-cluster fracturing mode.

[0138] Fracpro PT in the present embodiment is the English abbreviation of the hydraulic fracturing design analysis software, which is a prior art.

[0139] Example six:

[0140] According to Figure 1 A shale oil reservoir yield improvement and cost reduction fracturing optimization design method is shown in Figure 1, which is different from example one in that the specific method of step two is as follows,

[0141] First step: obtain the mine field temporary plugging construction data and temporary plugging diversion physical model test data;

[0142] Second step: according to the data obtained in the first step, establish a temporary plugging agent addition amount and temporary plugging pressure increase value distribution chart;

[0143] Third step: according to the temporary plugging agent addition amount and the temporary plugging pressure value distribution map obtained in the second step, the average plugging agent dosage corresponding to the temporary plugging pressure value greater than or equal to 10 MPa is taken as the single-stage temporary plugging agent addition amount;

[0144] Fourth step: using the numerical simulation software Meyer, the fracture morphology after different-stage temporary plugging fracturing under different cluster numbers is simulated, and the single-stage temporary plugging stage number is selected.

[0145] According to the results of field test, fracture temporary plugging diversion physical model test and numerical simulation analysis, the plugging agent addition amount and temporary plugging stage number parameters are optimized, which provides support for improving the multi-cluster fracture initiation efficiency of subsequent shale oil reservoir fracturing optimization design.

[0146] The numerical simulation software Meyer in the embodiment is prior art.

[0147] Example seven

[0148] According to Figure 1 The difference between the shale oil reservoir yield-increasing and cost-reducing fracturing optimization design method shown in the embodiment and the embodiment one is that the detailed process of establishing the economic evaluation system of key engineering modification parameters is as follows,

[0149] First step: collect the engineering modification parameters of shale oil horizontal wells, including the number of sections, the number of clusters, the fracture density, the liquid volume into the ground, the sand addition amount, the liquid injection intensity, the sand addition intensity, the displacement and the production data of 100-meter horizontal section half-year cumulative oil production, establish the relationship chart of each engineering modification parameter and 100-meter horizontal section half-year cumulative oil production, analyze the positive correlation of each engineering modification parameter and 100-meter horizontal section half-year cumulative oil production, and select the top three engineering modification parameters with positive correlation as the key engineering modification parameters;

[0150] Second step: according to the key engineering modification parameters obtained in the first step, the economic and effective recoverable reserves of single well under different key engineering modification parameters are measured, and the relationship chart of each key engineering modification parameter and the economic and effective recoverable reserves of single well is established;

[0151] Third step: according to the relationship between each key engineering modification parameter and the economic and effective recoverable reserves of single well obtained in the second step, the economic recommendation chart of different key engineering modification parameters is established, and the region corresponding to the technical and economic balance point of each parameter is selected, that is, the interval range of the economic maximization of each parameter.

[0152] The technical scheme of the present application establishes an economic evaluation system of key engineering reconstruction parameters by designing "mining field big data statistical regression + single well EUR comprehensive calculation + economic indicator sensitivity analysis", obtains an economic optimal range of key engineering reconstruction parameters, fully considers the contradiction between yield increase and cost reduction under the condition of low-cost development strategy, and provides strong data support for subsequent targeted shale oil reservoir yield increase and cost reduction fracturing optimization design of the target block.

[0153] Embodiment eight:

[0154] According to Figure 1 A shale oil reservoir yield increase and cost reduction fracturing optimization design method is shown in Figure 1, which is different from embodiment one in that the specific method for establishing the horizontal section reservoir segmentation and grading evaluation standard and selecting the horizontal section sweet spot in step four is as follows,

[0155] First step: obtain the horizontal well full section logging interpretation data including depth, vertical depth, acoustic time difference, density, gamma, shale content, effective porosity and oil saturation;

[0156] Second step: input the parameters obtained in the first step into the Fracpro PT fracturing software to perform rock mechanics parameter calculation and obtain the minimum horizontal principal stress and brittleness index parameters;

[0157] Third step: based on the reservoir quality parameters of effective porosity and oil saturation in the first step and the engineering quality parameters of minimum horizontal principal stress and brittleness index in the second step, establish the horizontal section reservoir segmentation and grading evaluation standard;

[0158] Fourth step: select the horizontal section sweet spot of the target well according to the horizontal section reservoir segmentation and grading evaluation standard.

[0159] Further, the horizontal section reservoir segmentation and grading evaluation standard divides the reservoir quality into I, II and III levels and the engineering quality into A, B and C levels according to the effective porosity, oil saturation, minimum horizontal principal stress and brittleness index, indicates that the comprehensive quality is good when the reservoir quality is I and the engineering quality is A, indicates that the comprehensive quality is poor when the reservoir quality is III or the engineering quality is C, and indicates that the comprehensive quality is medium in other cases.

[0160] The specific standard of the horizontal section reservoir segmentation and grading evaluation is as follows,

[0161]

[0162] In the table,

[0163] Φe—effective porosity, %;

[0164] So—oil saturation, %;

[0165] σh—minimum horizontal principal stress, MPa;

[0166] BI - brittleness index, %.

[0167] The technical scheme of the present application enables subsequent target blocks to be designed for shale oil reservoir yield increase and cost reduction fracturing optimization, which not only comprehensively considers yield increase concepts and main technologies, but also refers to parameter optimization results, thereby forming a high-quality shale oil reservoir fracturing optimization design scheme, which can greatly improve economic benefits.

[0168] Example Nine:

[0169] Referring to Figures 1-15 An application example of a shale oil reservoir yield increase and cost reduction fracturing optimization design method.

[0170] The reservoir porosity of a certain oil reservoir block in China is 4.6-13.2%, with an average of 10.5%, the permeability is 0.01-1.25x10 -3 μm 2 , the average is 0.39x10 -3 μm 2 , the oil saturation is 38%, the oil reservoir burial depth is 1968m, the initial formation pressure is 24.3MPa, the formation temperature is 88.9℃, the shale oil reservoir physical properties and oiliness are poor, and the rock brittleness index is low, the horizontal stress difference is large, the natural fracture development degree is low, and the single well production is low. Field big data shows that the initial production of this block is 9.6t / d, the annual cumulative oil production is 2380t, and based on the urgent form of shale oil scale benefit development, yield increase and cost reduction fracturing optimization design work is urgently needed.

[0171] The present example provides a complete shale oil reservoir yield increase and cost reduction fracturing optimization design method. The specific implementation includes practicing pressure displacement mining integrated development yield increase concepts, supporting main process technologies, designing key engineering modification parameter economic evaluation systems, and proposing shale oil reservoir yield increase and cost reduction fracturing optimization design methods.

[0172] 1. Practicing pressure displacement mining integrated development yield increase concepts: from the perspectives of high-density subdivision cutting fracturing, pre-pressing water supplementing formation energy, and oil displacement agent accelerating imbibition displacement, key parameters such as fracture spacing, ground liquid volume, and well soaking time are optimized.

[0173] (1) High-density subdivision cutting fracturing:

[0174] ①Through inputting reservoir boundary conditions, ground stress, elastic modulus, Poisson's ratio, permeability, porosity, fracturing fluid viscosity, filtration coefficient, construction displacement, pump-in time, and fracture location parameters into 3D-FEM, a three-dimensional finite element analysis software, the multi-cluster fracture propagation under different fracture spacing is simulated, and the multi-cluster fracture propagation diagram shows that when the fracture spacing is 5-10 m, the stress interference between fractures can increase the complexity of the fracture network, and the contact area between the fracture and the reservoir is increased, and the smaller the fracture spacing, the more obvious the stress interference.

[0175] ②Considering the matrix seepage rate, production pressure difference and starting pressure gradient of shale oil reservoir, the effective matrix seepage distance of shale oil reservoir is 3-5 m and the optimized fracture spacing is 6-10 m, which is calculated by using the one-dimensional linear seepage pressure distribution equation of low-permeability reservoir.

[0176] ③The complex fracture network model of multi-cluster fracturing is established by using Mangrove fracturing software, and the cumulative oil production is simulated when the horizontal section length is 80 m, the fracture spacing is 2.5 m, 5.0 m, 10 m, 15 m and 20 m, and the simulation results are shown in Figure 2 , it can be seen that when the fracture spacing is 5-10 m, the cumulative oil production is the highest, and the shale oil can be fully transformed.

[0177] ④Based on the above results, the optimal fracture spacing range of high-density fine-cutting fracturing is 6-10 m.

[0178] (2) Pre-fracturing water supplements formation energy:

[0179] ①Obtain and analyze the microseismic monitoring results, and establish a relationship chart between single-stage liquid volume and fracture zone length, as shown in Figure 3 , according to the full coverage principle of fractures, the single-stage liquid volume needs to reach 600-1000 m 3 under the condition of well spacing of 400-600 m.

[0180] ②According to the single-stage liquid volume of 600-1000 m 3 under the condition of well spacing of 400-600 m obtained in step (2) ①, the reservoir engineering formula ΔV=C t ·V·ΔP is used to calculate that when the formation energy in the fracture transformation volume range reaches 1.2 times of the original formation pressure, the single-stage liquid volume under the corresponding well spacing condition should be increased by 300-500 m 3 .

[0181] ③Based on the above results, the optimal single-stage liquid volume range of pre-fracturing water supplementing formation energy is 900-1500 m 3 .

[0182] (3) Oil displacement agent accelerates imbibition displacement:

[0183] ①Application of nuclear magnetic resonance and imaging system, carry out horizontal well core static imbibition experiment, establish the relationship between imbibition velocity and imbibition time, imbibition recovery and imbibition time, as shown in Figure 4 and Figure 5 , the results show that imbibition can reach equilibrium in a short time, after 40 days, imbibition effect is weakened, imbibition velocity and imbibition recovery change little, and the optimal soaking time for imbibition to reach equilibrium is 40-60 days.

[0184] ②Using mathematical analysis software Matlab to simulate the imbibition process of fracturing fluid in matrix, establish the relationship between soaking time and invasion distance, as shown in Figure 6 , the results show that with the increase of soaking time, the imbibition front of fracturing fluid in matrix is constantly advancing, when the soaking time reaches 40-60 days, the invasion distance of fracturing fluid changes gently, and the optimal soaking time for the invasion distance of fracturing fluid to reach equilibrium is 40-60 days.

[0185] ③Based on the above results, the optimal soaking time range for using new nano oil displacement variable viscosity slick water fracturing fluid system to speed up oil-water displacement efficiency is 40-60 days.

[0186] 2、Soluble ball seat subdivision cutting volume fracturing main technology: from the three aspects of soluble ball seat hard isolation, limited flow perforation dense seam and temporary plugging diversion soft subcluster, respectively optimize the parameters of horizontal well perforation cluster number, single cluster hole number, single hole flow, plugging agent addition and temporary plugging series.

[0187] (1) Soluble ball seat hard isolation: using full soluble metal ball seat for long horizontal well subdivision cutting volume fracturing, realizing unlimited stage fracturing and rapid cleaning after fracturing in horizontal well, and improving the operation ability of subdivision cutting volume fracturing.

[0188] (2) Limited flow perforation dense seam: get construction displacement, perforation hole number, perforation hole diameter and perforation hole and near wellbore region friction parameters, input the parameters into Fracpro PT fracturing software to calculate hole friction, draw hole friction calculation chart under different displacement and hole number, as shown in Figure 7 , according to the stress difference range of 2-3 MPa between clusters, use limited flow to overcome the stress difference between clusters, optimize the number of single stage clusters to 8-12 clusters, the number of single cluster holes to 2-9 holes per cluster, and the single hole flow to 0.3-0.4 m 3 / min.

[0189] (3) Temporary plugging diversion soft subcluster: according to the temporary plugging construction data and temporary plugging diversion physical model test data, establish the distribution chart of temporary plugging agent addition and temporary plugging pressure rise value, as shown in Figure 8As shown, the average plugging agent dosage of 25-45 kg corresponding to the optimized temporary plugging pressure increase value of ≥10 MPa is the single-stage temporary plugging agent dosage; the numerical simulation software Meyer is used to simulate the fracture morphology after fracturing under different cluster numbers (8-12 clusters) and different temporary plugging stages, and the single-stage temporary plugging is optimized to 1-2 stages, and when 8≤single-stage cluster number<10, 1-stage temporary plugging is performed, and when the single-stage cluster number≥10, 2-stage temporary plugging is performed.

[0190] 3. Establishing an economic evaluation system of key engineering modification parameters: from the three aspects of field big data statistical regression, single-well EUR comprehensive calculation, and economic index sensitivity analysis, the economic optimal range of key engineering modification parameters is optimized.

[0191] (1) Field big data statistical regression: collecting the engineering modification parameters of shale oil horizontal wells in the middle section, cluster number, fracture density, downhole liquid volume, sand volume, liquid injection intensity, sand injection intensity, displacement, and production data per 100-meter horizontal section, establishing the relationship chart between each engineering modification parameter and the cumulative oil production per 100-meter horizontal section for half a year, analyzing the positive correlation between each engineering modification parameter and the cumulative oil production per 100-meter horizontal section for half a year, selecting the top three engineering modification parameters with positive correlation as the key engineering modification parameters, and the results show that the three engineering modification parameters with the strongest positive correlation are fracture density, liquid injection intensity, and sand injection intensity.

[0192] (2) Single-well EUR comprehensive calculation: based on big data analysis, the single-well economic effective recoverable reserves (EUR) under different fracture densities, liquid injection intensities, and sand injection intensities are calculated, and the relationship chart between the three parameters and the single-well economic effective recoverable reserves (EUR) is established, as shown in Figure 9 , Figure 10 and Figure 11 .

[0193] (3) Economic index sensitivity analysis: according to the relationship between fracture density, liquid injection intensity, and sand injection intensity and single-well economic effective recoverable reserves obtained in step (2), the economic recommendation chart of each parameter is established with technical and economic optimization as the core, and the region corresponding to the technical and economic balance point of each parameter is optimized as the economic optimal range. The optimization results are fracture density 9-11 pieces / 100 m, liquid injection intensity 20-25 m 3 / m, and sand injection intensity 3.5-4.0 t / m, as shown in Figure 12 , Figure 13 and Figure 14 .

[0194] 4. Proposing a shale oil reservoir yield-increasing and cost-reducing fracturing optimization design method: according to the optimization results of yield-increasing, main technology, and engineering parameters, a shale oil reservoir yield-increasing and cost-reducing fracturing optimization design method is proposed for the target block.

[0195] (1) Stereoscopic well layout combined with horizontal section sweet spot optimization: adopt large well cluster multi-layer stereoscopic well layout, such as Figure 15 As shown in Table 1, rock mechanical parameters were calculated based on logging interpretation data from the entire horizontal well section. A segmented grading evaluation standard was established that considers both reservoir quality (RQ) and engineering quality (CQ) of horizontal wells. Based on the comprehensive evaluation results, a reservoir quality rating of I and an engineering quality rating of A indicates good overall quality, a reservoir quality rating of III or an engineering quality rating of C indicates poor overall quality, and the remaining ratings indicate moderate overall quality. Sweet spots in the horizontal section of the target well were selected. Shale oil reservoirs have been developed on a large scale through 3D horizontal well drilling and large-scale segmented, multi-cluster volumetric fracturing.

[0196] Table 1 Evaluation criteria for reservoir segmentation and classification of shale oil horizontal wells in target blocks

[0197]

[0198] Note: Φe——effective porosity, %; So——oil saturation, %; σh——minimum horizontal principal stress, MPa; BI——brittleness index, %.

[0199] (2) Propose an optimized design method for fracturing to increase production and reduce costs in the target block: Based on the optimization results of the three aspects of comprehensive development of production increase concept, main process technology, and key economic parameters, the block is optimized to use a large well cluster multi-layer three-dimensional well layout to improve the reservoir utilization, use a fully soluble metal ball seat for long horizontal well subdivision cutting volume fracturing, and cooperate with temporary plugging measures to improve the effectiveness of the fracturing of densely cut multi-cluster fractures. Among them, the preferred range of transformation parameters for the target block is: 8 to 12 clusters per segment, 6 to 10m fracture spacing, and 900 to 1500m of liquid flow per segment. 3 , crack density 9 to 11 / 100m, liquid inlet strength 20 to 25m 3 / m, sand addition intensity 3.5-4.0t / m; the preferred range of perforation parameters in the target block is: single-cluster hole number 2-9 holes / cluster, single-hole flow rate 0.3-0.4m 3 / min; the optimal range of temporary plugging parameters in the target block is: single-stage temporary plugging agent dosage is 25-45kg, single-stage temporary plugging is 1-2 levels; the optimal range of well blocking time in the target block is: well blocking for 40-60 days. Finally, based on the horizontal section reservoir segmentation and grading evaluation criteria that take into account both reservoir quality (RQ) and engineering quality (CQ), the horizontal section sweet spot is selected, and the optimized design parameters are used for reservoir transformation. The mine big data shows that after the fracturing optimization design, the initial production of the block increased from 9.6t / d to 18t / d, the annual cumulative oil production increased from 2380t to 4931t, and the predicted ultimate recoverable reserves (EUR) of a single well increased from 1.8×10 4 t increased to 2.6×10 4t, single well fracturing cost decreased from 20 million yuan in the early stage to 15 million yuan, barrel of oil cost decreased from 60 dollars to 40 dollars, and the overall economic benefit of 260 million yuan was realized.

[0200] In the case of no conflict, the skilled in the art can combine the relevant technical features in the above examples according to the actual situation to achieve the corresponding technical effects, and the specific combinations are not described one by one here.

[0201] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0202] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features.

[0203] The above is only the preferred embodiment of the present application, and the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application still belongs to the scope of the technical scheme of the present application.

Claims

1. A method for shale oil reservoir production yield and cost reduction fracturing optimization design, characterized in that: The method comprises the following steps, Step one: combine high-density fine cutting to form fractures, pre-bleeding water to supplement formation energy, and use nano oil displacement viscous slickwater fracturing fluid as oil displacement agent to accelerate imbibition displacement, optimize fracture spacing, single-stage ground liquid volume, and well soaking time range; Step two: use full-soluble metal ball seat to perform long horizontal well fine cutting volume fracturing, use limited flow perforation dense fracture and temporary plugging diversion soft sub-cluster to optimize horizontal well perforation cluster number, single cluster hole number, single hole flow, plugging agent addition, and temporary plugging series parameters; Step three: combine field big data statistical regression, single well EUR comprehensive measurement, and economic index sensitivity analysis to establish an economic evaluation system of key engineering modification parameters, and determine the economic optimal range of each key engineering modification parameter; Step four: use large well cluster multi-layer system three-dimensional well arrangement, establish horizontal section reservoir segmentation grading evaluation standard, select the horizontal section sweet spot of each horizontal well according to the reservoir segmentation grading evaluation result, and respectively develop large-scale segmented multi-cluster volume fracturing reconstruction; Step five: according to the results obtained in steps one to five, perform targeted shale oil reservoir yield increasing and cost reducing fracturing optimization design.

2. The shale oil reservoir production-increasing cost-reducing fracturing optimization design method of claim 1, wherein: The specific method for obtaining the fracture spacing range in the high-density fine cutting to form fractures in step one is as follows, First step: input the reservoir boundary condition, ground stress, elastic modulus, Poisson's ratio, permeability, porosity, fracturing fluid viscosity, filtration coefficient, construction displacement, pump-in time, and fracture position parameter into the three-dimensional finite element analysis software 3D-FEM to obtain the multi-cluster fracture propagation graph of the horizontal well in the shale oil reservoir under different fracture spacings, and select the fracture spacing of the complex fracture network with the largest contact area with the reservoir through the fracture propagation graph; Second step: use the following one-dimensional linear seepage pressure distribution equation (1) of the low-permeability reservoir to calculate the effective seepage distance of the matrix, and select the fracture spacing with the shortest seepage distance of the fluid in the matrix; （1） In the formula, P is the formation pressure, MPa; Pe is the original formation pressure, MPa; Pw is the bottom hole pressure, MPa; Pc is the casing pressure, MPa; G is the starting pressure gradient, MPa / m; s is the skin factor caused by the change of the permeability of the near-wellbore zone; x is the distance from the horizontal wellbore to the end, m; and L is the horizontal well length, m; Third step: use the Mangrove fracturing software to establish a multi-cluster fracturing complex fracture network model, simulate the relationship between different fracture spacings and the yield when the horizontal section length is constant, and select the fracture spacing with the largest cumulative yield; Fourth step: use the intersection of the fracture spacings in the first step to the third step as the fracture spacing range for high-density fine cutting to form fractures. The specific method for obtaining the single-stage ground liquid volume range in the pre-bleeding water to supplement formation energy in step one is as follows, First step: obtain and analyze the microseismic monitoring result, establish a single-stage ground liquid volume and fracture zone length relationship graph, and select the single-stage ground liquid volume meeting the fracture forming demand under the corresponding well spacing condition according to the fracture full coverage principle; ​ ​ ​ ​ ​ ​ 3. The method of claim 1, wherein: ​ ​ Second step: according to the single segment of the first step obtained into the ground liquid volume, using the relationship between the oil reservoir engineering into the ground liquid volume and formation pressure (2), calculate the corresponding well spacing conditions under the formation pressure coefficient to increase the preset value of the single segment of the ground liquid volume required to increase, select the single segment of the ground liquid volume to supplement the energy of the formation; （2） In the formula: V - fracture reformation volume - volume of liquid into the ground, m 3 ; C t - integrated compression coefficient, MPa -1 ; AV - liquid volume to be added, m 3 ; Delta P - the increase of the formation pressure, MPa; Third step: the first step obtained by superimposing the single segment of the ground liquid volume and the increment of the single segment of the ground liquid volume obtained in the second step, that is, the pre-pressing water to supplement the energy of the formation is obtained.

4. The method of claim 1, wherein: The specific method of the oil displacement agent in step one to accelerate the imbibition replacement to obtain the shut-in time range is as follows, First step: application of nuclear magnetic resonance and imaging system, horizontal well core static imbibition experiment, establishment of imbibition velocity-time relationship chart, imbibition recovery-time relationship chart, selection of imbibition balance shut-in time; Second step: using mathematical analysis software Matlab, simulate the imbibition process of fracturing fluid in matrix, establish the relationship between shut-in time and invasion distance, select the shut-in time when the invasion distance of fracturing fluid reaches balance; Third step: take the intersection of the shut-in time obtained in the first step and the second step as the shut-in time range of using nano oil displacement variable viscosity slick water fracturing fluid to accelerate oil-water displacement efficiency.

5. The method of claim 1, wherein: The specific method of the flow-restricted perforation dense seam in step two is as follows, First step: obtain the construction discharge, perforation hole number, perforation hole diameter and perforation hole and near wellbore region friction parameters, and input the parameters into Fracpro PT fracturing software to calculate the hole friction; Second step: draw the hole friction calculation chart under different discharge and hole number; Third step: according to the stress difference range between clusters, use flow restriction to overcome the stress difference between clusters, select single cluster number, single cluster hole number and single hole flow value.

6. The method of claim 1, wherein: The specific method of the temporary plugging and steering soft cluster in step two is as follows, First step: obtain the field temporary plugging construction data and temporary plugging and steering physical model test data; Second step: according to the data obtained in the first step, establish the temporary plugging agent addition amount and temporary plugging pressure increase value distribution chart; Third step: according to the temporary plugging agent addition amount and temporary plugging pressure increase value distribution chart obtained in the second step, the average plugging agent dosage corresponding to the temporary plugging pressure increase value greater than or equal to 10 MPa is selected as the single stage temporary plugging agent addition amount; Fourth step: using numerical simulation software Meyer, simulate the fracture morphology after fracturing under different cluster numbers and different stage temporary plugging, select the single stage temporary plugging stage number.

7. The method of claim 1, wherein: The detailed process of establishing the economic evaluation system of key engineering modification parameters in step three combined with field big data statistical regression, single well EUR comprehensive measurement and economic index sensitivity analysis is as follows, First step: collect the field shale oil horizontal well engineering modification parameters of section number, cluster number, fracture density, into the ground liquid volume, sand addition amount, liquid injection intensity, sand addition intensity, discharge and production data per hundred meter horizontal section half year cumulative oil production, establish the relationship chart between each engineering modification parameter and per hundred meter horizontal section half year cumulative oil production, analyze the positive correlation of each engineering modification parameter and per hundred meter horizontal section half year cumulative oil production, select the top three engineering modification parameters with positive correlation as the key engineering modification parameters; Second step: according to the key engineering modification parameters obtained in the first step, the economic and effective recoverable reserves of single well under different key engineering modification parameters are calculated respectively, and the relationship between each key engineering modification parameter and the economic and effective recoverable reserves of single well is established; Third step: according to the relationship between each key engineering modification parameter and the economic and effective recoverable reserves of single well obtained in the second step, the economic recommendation chart of different key engineering modification parameters is established, and the region corresponding to the technical and economic balance point of each parameter is selected, that is, the interval range of the economic maximization of each parameter.

8. The method of claim 1, wherein: The specific method for selecting the horizontal section sweet spot in the step four of establishing the horizontal section reservoir segmentation and grading evaluation standard is as follows, First step: obtain the full well section logging interpretation data of the horizontal well including depth, vertical depth, acoustic time difference, density, gamma, shale content, effective porosity and oil saturation; Second step: input the parameters obtained in the first step into the Fracpro PT fracturing software to calculate the rock mechanics parameters, and obtain the minimum horizontal principal stress and brittleness index parameters; Third step: based on the effective porosity and oil saturation of the reservoir quality parameters in the first step and the minimum horizontal principal stress and brittleness index of the engineering quality parameters in the second step, the horizontal section reservoir segmentation and grading evaluation standard is established; Fourth step: according to the horizontal section reservoir segmentation and grading evaluation standard, the horizontal section sweet spot of the target well is selected.

9. The method of claim 8, wherein: The horizontal section reservoir segmentation and grading evaluation standard is that the reservoir quality is divided into three levels of I, II and III according to the effective porosity, oil saturation, minimum horizontal principal stress and brittleness index, and the engineering quality is divided into three levels of A, B and C, when the reservoir quality is I and the engineering quality is A, it indicates that the comprehensive quality is good, when the reservoir quality is III or the engineering quality is C, it indicates that the comprehensive quality is poor, and the rest indicates that the comprehensive quality is medium.

Images