Tight sandstone reservoir fracturing evaluation method and device

Abstract

The present invention discloses a method and device for evaluating the fracturing of a tight sandstone reservoir, the method comprising: using rock samples of the tight sandstone reservoir to determine multiple fracturing evaluation indicators of the tight sandstone reservoir, regressing microseismic and volume fracturing data of fractured wells to obtain weight coefficients of multiple fracturing evaluation indicators of the tight sandstone reservoir, and determining the comprehensive fracturing coefficient of the tight sandstone reservoir according to different fracturing evaluation indicators of the tight sandstone reservoir and weight coefficients of different fracturing evaluation indicators. The present invention fully and comprehensively considers multiple fracturing evaluation indicators that affect the formation of a complex fracture network in the tight sandstone reservoir, and constructs a comprehensive brittleness evaluation model of the tight sandstone reservoir by combining weights, which can better reflect the comprehensive ability of the tight sandstone reservoir to form a complex fracture network during volume fracturing, and has high accuracy and operability.

Description

Technical Field

[0001] The invention relates to the technical field of geological exploration and development, and in particular to a method and a device for evaluating the vulnerability of a tight sandstone reservoir. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention recited in the claims. No admission is made that the description herein is prior art by inclusion in this section.

[0003] In order to obtain abundant tight oil and gas resources, the use of hydraulic fracturing technology to transform reservoirs is currently the core technology for developing tight oil and gas reservoirs.

[0004] Tight sandstone volume fracturing refers to the process of forming a criss-crossing network of fractures in tight sandstone reservoirs by injecting water and applying pressure in hydraulic fracturing technology. However, due to the unique reservoir occurrence and reservoir mechanical properties of tight reservoirs, whether an effective hydraulic fracture network can be formed during volume fracturing is controlled by many factors, such as geostress state, rock mechanical properties, degree of development of natural fractures in the reservoir, formation permeability and porosity, diagenesis and other reservoir properties and geomechanical factors, as well as engineering factors such as fracturing construction displacement, pumping mode, fracturing process, fracturing fluid and proppant type, completion method and flowback, production system, etc. Therefore, how to effectively improve the efficiency of volume fracturing, reduce the blindness of volume fracturing, and form a process method that matches the reservoir under the condition of a certain engineering scale has always been a hot topic in the current research of tight reservoir volume fracturing.

[0005] Reservoir brittleness only reflects the physical and geomechanical characteristics of the formation reservoir, as well as the comprehensive influence of the mechanical behaviors such as the initiation and expansion of rock fractures by pumping high-pressure fracturing fluid during volume fracturing, and has nothing to do with volume fracturing construction. The current brittleness evaluation methods mainly include qualitative and quantitative evaluation methods. The qualitative method mainly uses the method of directly comparing the research block data with the high-yield advantageous layers, well locations, and block data of tight reservoirs, and selects the well locations and layers for fracturing of tight reservoirs through geological, rock mechanics, logging, geophysics, and test production data. However, this method requires a large amount of previous historical data and is suitable for mature tight reservoir development blocks, and the error is sometimes large. The quantitative method is mainly based on the brittleness index. As the core index for selecting favorable layers for reservoir fracturing, the brittleness index considers the brittleness and fracture toughness of rocks. The brittleness evaluation model based on this is the most widely used reservoir brittleness evaluation method. However, the existing brittleness index evaluation method still requires other parameters to be obtained indirectly, and it cannot be directly tested.

[0006] Accurate rock mechanics parameters are the basic data for reservoir brittleness assessment. However, brittleness indicators generally require sufficient indoor experimental data or high-precision logging data. For example, it is difficult to obtain acoustic logging data in the horizontal section due to the limitations of logging costs and downhole tools. Secondly, rock mechanics and physical experiments have high requirements for the quality of the rock itself, and also have defects such as high testing costs and long testing cycles. At the same time, sometimes there are not enough cores on site, so there are large individual differences during testing. Sometimes only discrete brittleness assessment data of different layers can be obtained, which is difficult to support the fracturing design of the entire well section. In addition, existing uniaxial or triaxial rock mechanics experiments will destroy the rock after the experiment, so the core test results are difficult to re-verify, and cannot be analyzed jointly with other rock physics results, and the application value is greatly reduced.

[0007] Rock fracture toughness refers to the condition under elastic-plastic conditions where when the stress field intensity factor increases to a certain critical value, the cracks will expand unstably. Fracture toughness reflects the ability of rocks to resist unstable expansion of cracks. It is an important indicator of rocks after peak damage and can reflect the comprehensive damage properties of rocks before and after the peak. For this reason, many scholars advocate taking rock fracture toughness into account in the comprehensive evaluation of reservoirs. However, the current three-point bending, straight-slit Brazilian disc and other experiments consume a lot of samples and it is difficult to conduct multi-position tests.

[0008] In summary, there are two urgent problems that need to be solved in the evaluation of tight reservoir brittleness: (1) How to use small-scale rock samples to test the high-precision rock mechanical properties. (2) Combined with the characteristics of the block, considering comprehensive factors to form a comprehensive brittleness evaluation model with high operability. Summary of the invention

[0009] The embodiment of the present invention provides a method for evaluating the fracturing of a tight sandstone reservoir, which is used to improve the test accuracy of rock mechanical properties and construct a comprehensive brittleness evaluation model that includes multiple comprehensive factors and has high operability. The method for evaluating the fracturing of a tight sandstone reservoir includes:

[0010] Using rock samples from tight sandstone reservoirs, multiple fracturing evaluation indicators of tight sandstone reservoirs are determined;

[0011] The weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs are obtained through regression of microseismic and volume fracturing data of fractured wells.

[0012] According to different fracturing evaluation indicators of tight sandstone reservoirs and their weight coefficients, the comprehensive fracturing coefficient of tight sandstone reservoirs is determined.

[0013] The embodiment of the present invention further provides a tight sandstone reservoir evaluation device, which is used to improve the test accuracy of rock mechanical properties and construct a comprehensive brittleness evaluation model that includes multiple comprehensive factors and has high operability. The tight sandstone reservoir evaluation device includes:

[0014] A fracturing evaluation index determination module is used to determine multiple fracturing evaluation indexes of the tight sandstone reservoir using rock samples of the tight sandstone reservoir;

[0015] A weight coefficient determination module is used to obtain weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs through regression of microseismic and volume fracturing data of fractured wells;

[0016] The comprehensive fracturing coefficient determination module is used to determine the comprehensive fracturing coefficient of the tight sandstone reservoir according to different fracturing evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturing evaluation indicators.

[0017] An embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned tight sandstone reservoir fracturing evaluation method when executing the computer program.

[0018] An embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the above-mentioned tight sandstone reservoir fracturing evaluation method.

[0019] In the embodiment of the present invention, a plurality of fracturing evaluation indicators of the tight sandstone reservoir are determined by using rock samples of the tight sandstone reservoir, and the weight coefficients of the plurality of fracturing evaluation indicators of the tight sandstone reservoir are obtained by regressing the microseismic and volume fracturing data of the fractured wells, and the comprehensive fracturing coefficient of the tight sandstone reservoir is determined according to the different fracturing evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturing evaluation indicators. The embodiment of the present invention fully considers the plurality of fracturing evaluation indicators that affect the formation of a complex fracture network in the tight sandstone reservoir, comprehensively considers the plurality of fracturing evaluation indicators, and constructs a comprehensive brittleness evaluation model (i.e., comprehensive fracturing coefficient) of the tight sandstone reservoir by combining weights, and the comprehensive brittleness evaluation model thus obtained can better reflect the comprehensive ability of the tight sandstone reservoir to form a complex fracture network during volume fracturing, and has high accuracy and operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. 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 creative work. In the drawings:

[0021] Figure 1 A flowchart of the implementation of the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention;

[0022] Figure 2 Another implementation flow chart of the tight sandstone reservoir fracturing evaluation method provided by an embodiment of the present invention;

[0023] Figure 3 A flowchart for implementing step 201 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0024] Figure 4 A flowchart for implementing step 101 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0025] Figure 5 A flowchart for implementing step 401 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0026] Figure 6 A flowchart for implementing step 402 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0027] Figure 7 A flowchart for implementing step 403 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0028] Figure 8 A flowchart for implementing step 404 in the tight sandstone reservoir fracturing evaluation method provided in an embodiment of the present invention;

[0029] Fig. 9 A functional module diagram of a tight sandstone reservoir evaluation device provided by an embodiment of the present invention;

[0030] Fig.10 Another functional module diagram of the tight sandstone reservoir evaluation device provided by an embodiment of the present invention;

[0031] Fig.11 A structural block diagram of a preprocessing module 1001 in a tight sandstone reservoir evaluation device provided in an embodiment of the present invention;

[0032] Fig.12A structural block diagram of a fracturing evaluation index determination module 901 in a tight sandstone reservoir evaluation device provided in an embodiment of the present invention;

[0033] Fig.13 A structural block diagram of a hardness and brittleness index determination unit 1201 in a tight sandstone reservoir evaluation device provided in an embodiment of the present invention;

[0034] Fig.14 A structural block diagram of a fracture toughness brittleness index determination unit 1202 in a tight sandstone reservoir evaluation device provided in an embodiment of the present invention;

[0035] Fig.15 A structural block diagram of the elastic brittleness index determination unit 1203 in the tight sandstone reservoir evaluation device provided in an embodiment of the present invention;

[0036] Fig.16 This is a structural block diagram of the mineralogical brittleness index determination unit 1204 in the tight sandstone reservoir evaluation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0038] Figure 1 The implementation process of the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0039] like Figure 1 As shown, a tight sandstone reservoir fracturing evaluation method comprises:

[0040] Step 101, using rock samples of a tight sandstone reservoir to determine multiple fracturing evaluation indicators of the tight sandstone reservoir;

[0041] Step 102, obtaining weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs through regression of microseismic and volume fracturing data of fractured wells;

[0042] Step 103: determining a comprehensive fracturability coefficient of the tight sandstone reservoir according to different fracturability evaluation indicators of the tight sandstone reservoir and weight coefficients of the different fracturability evaluation indicators.

[0043] When conducting fracturing evaluation on tight sandstone reservoirs, firstly, rock samples used in the experiment are collected from the tight sandstone reservoirs, and the size and quality of the rock samples are processed and screened to select rock samples suitable for the experiment. Among them, the thickness of the selected tight sandstone reservoir rock samples is not less than the first rock thickness, the length is not less than the first rock length, the width is not less than the first rock width, and more than two rock samples are collected at the same depth point of the tight sandstone reservoir.

[0044] The first rock thickness is a preset rock thickness, and those skilled in the art may preset the first rock thickness according to actual conditions and specific requirements. For example, the first rock thickness may be preset to 10 mm, or the first rock thickness may be preset to 9 mm or 11 mm. Those skilled in the art may understand that the first rock thickness may also be preset to other values ​​other than the above 10 mm, 9 mm or 11 mm, for example, the first rock thickness may be preset to 8 mm or 12 mm, etc., and the embodiment of the present invention does not impose any particular limitation on this.

[0045] The first rock length and / or width is a preset rock length and / or width, and those skilled in the art may preset the first rock length and / or width according to actual conditions and specific requirements. For example, the first rock length and / or width is preset to 20 mm, or the first rock length and / or width is preset to 19 mm or 21 mm. Those skilled in the art may understand that the first rock length and / or width may be preset to other values ​​other than the above 20 mm, 19 mm or 21 mm, for example, the first rock length and / or width may be preset to 18 mm or 22 mm, etc. The embodiment of the present invention does not impose any particular limitation on this.

[0046] After selecting appropriate rock samples of tight sandstone reservoirs, the collected and selected rock samples of tight sandstone reservoirs are used to determine multiple fracturing evaluation indicators that affect the formation of complex fracture networks in tight sandstone reservoirs. At the same time, the weight coefficients of multiple fracturing evaluation indicators can be obtained by regressing the microseismic and volume fracturing data of fractured wells. For example, the weight coefficients can be obtained by inverting the actual fracturing evaluation results of adjacent wells.

[0047] After obtaining multiple fracturing evaluation indicators of tight sandstone reservoirs and weight coefficients of multiple fracturing evaluation indicators respectively, the comprehensive fracturing coefficient of tight sandstone reservoirs can be determined based on the above multiple fracturing evaluation indicators and their weight coefficients. The comprehensive fracturing coefficient is a comprehensive brittleness evaluation model of tight sandstone reservoirs based on combined weight coefficients, reflecting the degree of fracturing of tight sandstone reservoirs. The larger the comprehensive fracturing coefficient, the higher the degree of fracturing of tight sandstone reservoirs, and the easier it is to form a complex fracture network when fracturing the tight sandstone reservoir; the smaller the comprehensive fracturing coefficient, the lower the degree of fracturing of tight sandstone reservoirs, and the less likely it is to form a complex fracture network when fracturing the tight sandstone reservoir.

[0048] Specifically, the comprehensive fracturing coefficient of tight sandstone reservoir can be determined by the following formula:

[0049]

[0050]

[0051] i=1,2,…,n-1,n and n≥2

[0052] Where B represents the comprehensive fracturing coefficient of tight sandstone reservoir, B id Represents the fracturing evaluation index, R i represents the weight coefficient of the fracturing evaluation index, and n represents the number of weight coefficients of the fracturing evaluation index.

[0053] In an embodiment of the present invention, a plurality of fracturing evaluation indicators of the tight sandstone reservoir are determined by using rock samples of the tight sandstone reservoir, and the weight coefficients of the plurality of fracturing evaluation indicators of the tight sandstone reservoir are obtained by regressing the microseismic and volume fracturing data of the fractured wells, and the comprehensive fracturing coefficient of the tight sandstone reservoir is determined according to the different fracturing evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturing evaluation indicators. The embodiment of the present invention fully considers the plurality of fracturing evaluation indicators that affect the formation of a complex fracture network in the tight sandstone reservoir, comprehensively considers the plurality of fracturing evaluation indicators, and constructs a comprehensive brittleness evaluation model (i.e., comprehensive fracturing coefficient) of the tight sandstone reservoir by combining weights, and the comprehensive brittleness evaluation model thus obtained can better reflect the comprehensive ability of the tight sandstone reservoir to form a complex fracture network during volume fracturing, and has high accuracy and operability.

[0054] Figure 2 Another implementation process of the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0055] In one embodiment of the present invention, in order to further improve the accuracy of determining the comprehensive fracturability coefficient, as Figure 2 As shown in the above, the evaluation method of tight sandstone reservoir fracturing Figure 1 Based on the steps of the method shown, it also includes:

[0056] Step 201, pre-processing the rock fragments of the tight sandstone reservoir to obtain the pre-processed rock fragments of the tight sandstone reservoir;

[0057] Step 101, using rock samples of a tight sandstone reservoir, to determine a plurality of fracturing evaluation indices of the tight sandstone reservoir, including:

[0058] Step 202: using the pre-processed rock samples of the tight sandstone reservoir, determine a plurality of fracturing evaluation indices of the tight sandstone reservoir.

[0059] Before determining multiple fracturing evaluation indicators of tight sandstone reservoirs, the rock samples of tight sandstone reservoirs can be pre-processed, such as cleaning, grinding and polishing, so that the rock samples of tight sandstone reservoirs can better meet the experimental requirements and improve the precision and accuracy of the experiment. Then, the rock samples of tight sandstone reservoirs after pretreatment can be used to determine multiple fracturing evaluation indicators of tight sandstone reservoirs.

[0060] In an embodiment of the present invention, rock fragments of a tight sandstone reservoir are preprocessed to obtain preprocessed rock fragments of the tight sandstone reservoir. The preprocessed rock fragments of the tight sandstone reservoir are used to determine multiple fracturing evaluation indicators of the tight sandstone reservoir, which can further improve the accuracy of determining the comprehensive fracturing coefficient.

[0061] In one embodiment of the present invention, in order to improve the intuitiveness of the fracturing degree of the tight sandstone reservoir, as Figure 2 As shown in the above Figure 1 Based on the steps shown in the method, the tight sandstone reservoir fracturing evaluation method further includes:

[0062] Step 203: Determine the fracturability grade of the tight sandstone reservoir corresponding to the comprehensive fracturability coefficient according to the comprehensive fracturability coefficient of the tight sandstone reservoir.

[0063] When determining the degree of fracturing of a tight sandstone reservoir, the fracturing grade of the tight sandstone reservoir can be divided. For example, when the comprehensive fracturing coefficient of the tight sandstone reservoir is less than 0.33, the fracturing grade of the tight sandstone reservoir is considered to be a low fracturing grade; when the comprehensive fracturing coefficient of the tight sandstone reservoir is not less than 0.33 and not greater than 0.66, the fracturing grade of the tight sandstone reservoir is considered to be a medium fracturing grade; when the comprehensive fracturing coefficient of the tight sandstone reservoir is greater than 0.66 and not greater than 1, the fracturing grade of the tight sandstone reservoir is considered to be a high fracturing grade.

[0064] It can be understood by those skilled in the art that the fracturability level of the tight sandstone reservoir can be classified into other levels besides the above-mentioned level classification. For example, when the comprehensive fracturability coefficient of the tight sandstone reservoir is less than 0.2, the fracturability level of the tight sandstone reservoir is considered to be a low fracturability level; when the comprehensive fracturability coefficient of the tight sandstone reservoir is not less than 0.20 and not more than 0.40, the fracturability level of the tight sandstone reservoir is considered to be a low fracturability level; when the comprehensive fracturability coefficient of the tight sandstone reservoir is not less than 0.40 and not more than 0.60, the fracturability level of the tight sandstone reservoir is considered to be a medium fracturability level; when the comprehensive fracturability coefficient of the tight sandstone reservoir is not less than 0.60 and not more than 0.80, the fracturability level of the tight sandstone reservoir is considered to be a high fracturability level; when the comprehensive fracturability coefficient of the tight sandstone reservoir is greater than 0.80 and not greater than 1, the fracturability level of the tight sandstone reservoir is considered to be a high fracturability level, etc.

[0065] Accordingly, based on the comprehensive fracturing coefficient of the tight sandstone reservoir, the fracturing grade corresponding to the comprehensive fracturing coefficient can be used as the fracturing grade of the tight sandstone reservoir.

[0066] In the embodiment of the present invention, the fracturability grade of the tight sandstone reservoir corresponding to the comprehensive fracturability coefficient of the tight sandstone reservoir is determined according to the comprehensive fracturability coefficient of the tight sandstone reservoir, which can improve the intuitiveness of the fracturability degree of the tight sandstone reservoir.

[0067] Figure 3 The implementation process of step 201 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0068] In one embodiment of the present invention, in order to further improve the accuracy of determining the comprehensive fracturability coefficient, as Figure 3 As shown, step 201, pre-processing the rock samples of the tight sandstone reservoir to obtain the pre-processed rock samples of the tight sandstone reservoir, includes:

[0069] Step 301, using a chemical cleaning agent to clean the collected rock samples to obtain cleaned rock samples; and / or

[0070] Step 302, grinding and polishing the collected rock fragments by mechanical polishing to obtain the ground and polished rock fragments.

[0071] Before using rock samples to determine multiple fracturing evaluation indicators, the rock samples can be cleaned using a chemical cleaning agent that is less harmful to the rock samples, such as using acetone and other chemical cleaning agents to clean the rock samples to obtain cleaned rock samples.

[0072] In addition, the rock samples can be ground and polished by mechanical polishing to obtain the ground and polished rock samples. The grinding and polishing indentation depth should not be less than the first indentation depth, so as to eliminate the influence of surface microcracks on the indentation test or scratch test results.

[0073] The first indentation depth is a preset indentation depth, and those skilled in the art may preset the first indentation depth according to actual conditions and specific requirements. For example, the first indentation depth may be preset to 20 microns, or the first indentation depth may be preset to 19 microns or 21 microns. Those skilled in the art may understand that the first indentation depth may be preset to other values ​​other than the above 20 microns, 19 microns or 21 microns, for example, the first indentation depth may be preset to 18 microns or 22 microns, etc. The embodiment of the present invention does not impose any particular limitation on this.

[0074] In an embodiment of the present invention, the collected rock samples are cleaned with a chemical cleaning agent to obtain cleaned rock samples, and / or the collected rock samples are ground and polished with mechanical polishing to obtain ground and polished rock samples, which can further improve the accuracy of determining the comprehensive fracturability coefficient.

[0075] Figure 4 The implementation process of step 101 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0076] In one embodiment of the present invention, the multiple fracturing evaluation indicators include at least three of the following four fracturing evaluation indicators: hardness brittleness indicator, fracture toughness brittleness indicator, elastic mechanics brittleness indicator and mineralogy brittleness indicator. In order to comprehensively consider multiple fracturing evaluation indicators that affect the formation of complex fracture networks in tight sandstone reservoirs, and improve the comprehensive ability of the comprehensive brittleness evaluation model to reflect the formation of complex fracture networks in tight sandstone reservoirs during volume fracturing, such as Figure 4 As shown, step 101, using rock samples of the tight sandstone reservoir, determines multiple fracturing evaluation indicators of the tight sandstone reservoir, including:

[0077] Step 401, using rock samples of the tight sandstone reservoir to determine the hardness and brittleness index of the tight sandstone reservoir;

[0078] Step 402, using rock samples of the tight sandstone reservoir, determining the fracture toughness and brittleness index of the tight sandstone reservoir;

[0079] Step 403, using the rock samples of the tight sandstone reservoir, determining the elastic mechanical brittleness index of the tight sandstone reservoir;

[0080] Step 404: using the rock samples of the tight sandstone reservoir, determine the mineralogical brittleness index of the tight sandstone reservoir.

[0081] When evaluating the fracturing of a tight sandstone reservoir, a comprehensive evaluation can be performed using multiple indicators such as the hardness brittleness index, fracture toughness brittleness index, elastic mechanics brittleness index, and mineralogical brittleness index of the tight sandstone reservoir. In an embodiment of the present invention, three of the above four evaluation indicators can be used to comprehensively evaluate the fracturing of a tight sandstone reservoir, for example, the hardness brittleness index, elastic mechanics brittleness index, and mineralogical brittleness index of a tight sandstone reservoir can be used to comprehensively evaluate the fracturing of a tight sandstone reservoir; or the fracture toughness brittleness index, elastic mechanics brittleness index, and mineralogical brittleness index of a tight sandstone reservoir can be used to comprehensively evaluate the fracturing of a tight sandstone reservoir; or the above four evaluation indicators can be used in combination to comprehensively evaluate the fracturing of a tight sandstone reservoir, etc.

[0082] Among them, the hardness brittleness index of tight sandstone reservoir is a brittleness index based on rock hardness parameters, the fracture toughness brittleness index of tight sandstone reservoir is a brittleness index based on rock fracture toughness parameters, the elastic mechanical brittleness index of tight sandstone reservoir is a brittleness index based on rock elastic mechanical parameters, and the mineralogical brittleness index of tight sandstone reservoir is a brittleness index based on mineral composition.

[0083] In an embodiment of the present invention, the hardness and brittleness index of the tight sandstone reservoir is determined by using rock samples of the tight sandstone reservoir, the fracture toughness and brittleness index of the tight sandstone reservoir is determined by using rock samples of the tight sandstone reservoir, the elastic mechanical brittleness index of the tight sandstone reservoir is determined by using rock samples of the tight sandstone reservoir, and the mineralogical brittleness index of the tight sandstone reservoir is determined by using rock samples of the tight sandstone reservoir. The fracturing ability of the tight sandstone reservoir is comprehensively evaluated using three or four evaluation indicators among the above indicators, and multiple fracturing evaluation indicators that affect the formation of a complex fracture network in the tight sandstone reservoir can be comprehensively considered, thereby improving the comprehensive ability, accuracy and operability of the comprehensive brittleness evaluation model to reflect the formation of a complex fracture network in the tight sandstone reservoir during volume fracturing.

[0084] Figure 5 The implementation process of step 401 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0085] In one embodiment of the present invention, in order to improve the accuracy of determining the hardness brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), as Figure 5 As shown, step 401, using rock samples of the tight sandstone reservoir, determines the hardness and brittleness index of the tight sandstone reservoir, including:

[0086] Step 501, performing an indentation test on a rock sample of a tight sandstone reservoir by using a micron indentation technique to obtain a load-displacement curve of an indenter on the surface of the rock sample;

[0087] Step 502, determining the hardness parameter of the rock sample using the load displacement curve of the indenter on the surface of the rock sample;

[0088] Step 503, determining an average hardness parameter of the rock samples according to the hardness parameters of the rock samples of the tight sandstone reservoir;

[0089] Step 504, using the average hardness parameter of the rock sample, determine the hardness and brittleness index of the rock sample through normalization.

[0090] Rock hardness is a key indicator of the hardness level of the rock itself, and has a certain relationship with the Young's modulus, compressive strength and other parameters of the rock. Micro-indentation technology can easily obtain rock hardness data by recording displacement load curves, thus providing a new perspective for more comprehensive determination of rock brittleness from the perspective of hardness.

[0091] When determining the hardness and brittleness indexes of rock samples, the rock samples of tight sandstone reservoirs are firstly indented by micron indentation technology. The load-displacement curve of the indenter on the surface of the rock sample can be obtained through the indentation experiment, and then the hardness parameters of the rock sample can be determined through the load-displacement curve of the indenter on the surface of the rock sample.

[0092] The number of micron indentation tests on each rock sample should be above the first number so that it can be placed on a micron indentation test stand during testing. The first number is a pre-set number, and those skilled in the art can pre-set the first number based on actual conditions and specific needs. For example, the first number is pre-set to 10 times, or the first number is pre-set to 9 times or 11 times. It will be understood by those skilled in the art that the first number can also be pre-set to other values ​​other than the above 10 times, 9 times or 11 times, such as pre-setting the first number to 8 times or 12 times, etc. The embodiment of the present invention does not impose any particular limitation on this.

[0093] Specifically, the hardness parameter of the rock sample can be determined by using the load-displacement curve through the following formula:

[0094]

[0095]

[0096]

[0097]

[0098] Among them, H1 represents the hardness parameter of rock sample, P max Indicates the maximum load, A c represents the contact projection area under the corresponding load, h c Denotes the contact depth, h max represents the total penetration depth, v E It represents the Poisson's ratio (dimensionless) of the rock sample, ε represents a constant related to the pressure head. For the wave-type pressure head, it is generally taken as 0.75, and S represents the contact stiffness of the system.

[0099] After determining the hardness parameter of each rock sample, perform arithmetic averaging on the hardness parameter of each rock sample, and then use the average hardness parameter of the rock sample as the hardness parameter of the rock sample, so as to use the average hardness parameter of the rock sample to determine the hardness and brittleness index of the rock sample by normalization method. It should also be noted that when selecting the average value to calculate the data point, it is necessary to clean the data for the points with large fluctuations, and the test indentation depth should be at least higher than 3000nm. Among them, the normalization method can at least include maximum value normalization.

[0100] Specifically, the normalized hardness and brittleness index can be obtained by the following maximum value normalization method:

[0101]

[0102] Among them, B 1d It indicates the hardness and brittleness index of rock samples, H indicates the average hardness parameter of rock samples tested, and H max Indicates the maximum hardness value among all the hardness parameters of rock samples, H min Indicates the minimum hardness value among the hardness parameters of all rock samples.

[0103] In an embodiment of the present invention, an indentation test is performed on a rock sample of a tight sandstone reservoir by using a micron indentation technique to obtain a load displacement curve of the indenter on the surface of the rock sample, and the hardness parameter of the rock sample is determined by using the load displacement curve of the indenter on the surface of the rock sample. The average hardness parameter of the rock sample is determined according to the hardness parameter of the rock sample of the tight sandstone reservoir, and the hardness and brittleness index of the rock sample is determined by normalization using the average hardness parameter of the rock sample. In an embodiment of the present invention, the hardness parameter of the rock sample is determined by using a micron indentation technique, and then the hardness and brittleness index of the rock sample is determined by normalization, which can improve the accuracy of determining the hardness and brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0104] Figure 6 The implementation process of step 402 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0105] In one embodiment of the present invention, in order to improve the accuracy of determining the fracture toughness brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), as Figure 6 As shown, step 402, using rock samples of the tight sandstone reservoir, determines the fracture toughness and brittleness index of the tight sandstone reservoir, including:

[0106] Step 601, performing a scratch test on a rock sample of a tight sandstone reservoir by using a micron scratch technique to obtain a friction curve of an indenter on the surface of the rock sample;

[0107] Step 602, determining the fracture toughness of the rock sample using a friction curve of the indenter on the surface of the rock sample;

[0108] Step 603, determining the average fracture toughness of the rock samples according to the fracture toughness of the rock samples of the tight sandstone reservoir;

[0109] Step 604, using the average fracture toughness of the rock samples, determine the fracture toughness brittleness index of the rock samples through normalization.

[0110] Micron scratch technology collects relevant elastic-plastic deformation information by destroying the bond between the sample surface and the matrix, thereby obtaining elastic-plastic deformation information. Through further analysis, important mechanical parameters such as critical load and friction can be obtained, and the fracture toughness parameters of the rock can be calculated. At the same time, since the scratch area is only completed on the rock surface, it will not damage the rock itself. The rock scratch test is a convenient and fast non-destructive test method for fracture toughness. The micron scratch mechanical experiment is an important method for testing the fracture toughness of the material surface. Under the condition of assuming that a horizontal crack is generated at the top of the indenter, the stress component is solved, and then the strain energy release rate of the system is solved in combination with the J integral. Then, the plane strain fracture toughness can be obtained according to the quasi-fracture criterion.

[0111] When determining the fracture toughness and brittleness index of rock samples, the rock samples of tight sandstone reservoirs are first scratched using micron scratch technology to obtain the friction curve of the indenter on the surface of the rock samples, and then the fracture toughness of the rock samples is determined through the friction curve of the indenter on the surface of the rock samples.

[0112] Specifically, the fracture toughness of rock samples can be determined using the friction curve using the following formula:

[0113]

[0114]

[0115]

[0116] Among them, Kc represents the fracture toughness of the rock sample, G represents the strain energy release rate, E represents the Young's modulus of the rock sample, v represents the Poisson's ratio of the rock sample, and F T represents the tangential force, 2pA represents the shape function of the indenter, p represents the circumference of the contact part between the indenter and the material in the x-axis direction, A represents the projected area of ​​the contact part between the indenter and the material in the x-axis direction, and F eq Expressed with tangential force F T and the vertical force F v When the angle between the axis of the pressure head and the vertical axis is equal to 0, F eq =F T d represents the scratch depth, and the tangential force F T The scratch depth d can be obtained through scratch experiments, and θ represents the half-apex angle of the indenter.

[0117] After the fracture toughness of each rock sample is determined, the fracture toughness of each rock sample is arithmetic averaged, and then the average fracture toughness of the rock sample is used as the fracture toughness of the rock sample, so as to use the average fracture toughness of the rock sample to determine the fracture toughness brittleness index of the rock sample by a normalization method. The normalization method may at least include maximum value normalization.

[0118] Specifically, the normalized fracture toughness and brittleness index of the rock sample can be obtained by the following maximum value normalization method:

[0119]

[0120] Among them, B 2d Indicates the fracture toughness brittleness index of rock samples, K cmax Indicates the maximum fracture toughness of the rock sample, K cmin Indicates the minimum value of fracture toughness among the fracture toughness of rock samples, K c Indicates the fracture toughness of rock samples.

[0121] In an embodiment of the present invention, a scratch test is performed on a rock sample of a tight sandstone reservoir by using a micron scratch technique to obtain a friction curve of the indenter on the surface of the rock sample, and the fracture toughness of the rock sample is determined by using the friction curve of the indenter on the surface of the rock sample. The average fracture toughness of the rock sample is determined based on the fracture toughness of the rock sample of the tight sandstone reservoir, and the fracture toughness brittleness index of the rock sample is determined by normalization using the average fracture toughness of the rock sample. The embodiment of the present invention determines the fracture toughness of the rock sample by using a micron scratch test, and then determines the fracture toughness brittleness index of the rock sample by normalization, which can improve the accuracy of determining the fracture toughness brittleness index, and then improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0122] Figure 7 The implementation process of step 403 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0123] In one embodiment of the present invention, in order to improve the accuracy of determining the elastic brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), as follows Figure 7 As shown, step 403, using the rock samples of the tight sandstone reservoir, determines the elastic mechanical brittleness index of the tight sandstone reservoir, including:

[0124] Step 701, using a rock sonicator to measure the longitudinal wave velocity and the transverse wave velocity of a rock sample of a tight sandstone reservoir;

[0125] Step 702, determining the Young's modulus and Poisson's ratio of the rock sample according to the longitudinal wave velocity and the transverse wave velocity of the rock sample;

[0126] Step 703, determining the elastic brittleness index of the rock fragments by normalization according to the Young's modulus and Poisson's ratio of the rock fragments.

[0127] The test of micro-sample elastic mechanics samples (rock fragments) needs to be completed in a special rock sonic instrument. The basic principle of the test is the pulse wave velocity measurement technology, which can complete the sonic test of a sample as small as 1mm. During the measurement, the test dense sandstone rock sample (rock fragment) needs to be placed between the two probes of the rock sonic instrument and pressed tightly. The sonic velocity of the sample is obtained based on the average thickness of the rock itself and the time it takes for the sound wave to pass through the rock sample. When determining the elastic brittleness index of the rock fragment, the longitudinal and transverse wave velocities of the rock fragments of the dense sandstone reservoir are first measured by the rock sonic instrument.

[0128] Specifically, the longitudinal wave velocity and the transverse wave velocity of the rock sample can be determined by the following formulas:

[0129]

[0130]

[0131] Among them, K p represents the influencing factors of the longitudinal wave velocity related to the drilling fluid and the immersion time, D represents the average thickness of the cuttings, T p represents the time required for the longitudinal sound wave to travel through the rock cuttings, K s represents the influencing factors of shear wave velocity related to drilling fluid and immersion time, T s It is the time required for the longitudinal sound wave to pass through the rock cuttings, V p represents the longitudinal wave velocity of rock fragments, V s Represents the shear wave velocity of rock fragments.

[0132] After respectively determining the longitudinal wave velocity and the transverse wave velocity of the rock sample, the Young's modulus of the rock sample can be determined by the following formula:

[0133]

[0134] Among them, E d represents the Young's modulus of the rock fragments, ρ represents the density of the rock fragments, V p represents the longitudinal wave velocity of rock fragments, V s Represents the shear wave velocity of rock fragments.

[0135] After respectively determining the longitudinal wave velocity and the transverse wave velocity of the rock sample, the Poisson's ratio of the rock sample can be determined by the following formula:

[0136]

[0137] Among them, v d The Poisson's ratio of the rock sample, V p represents the longitudinal wave velocity of rock fragments, V s Represents the shear wave velocity of rock fragments.

[0138] After respectively determining the Young's modulus and the Poisson's ratio of the rock sample, the elastic brittleness index of the rock sample is determined, and then the elastic brittleness index of the rock sample is determined by a normalization method, wherein the normalization method may at least include maximum value normalization.

[0139] Specifically, the elastic brittleness index of the normalized rock sample can be obtained by the following maximum value normalization method:

[0140]

[0141]

[0142] Among them, B3 represents the elastic brittleness index of rock samples, E d represents the Young's modulus of the rock sample, v d The Poisson's ratio of the rock sample, B 3max Indicates the maximum value of the elastic brittleness index among the elastic brittleness indexes of rock samples, B 3min It represents the minimum value of the elastic brittleness index among the elastic brittleness indexes of rock fragments.

[0143] In an embodiment of the present invention, a rock sonic instrument is used to measure the longitudinal wave velocity and the transverse wave velocity of a rock sample of a tight sandstone reservoir, and the Young's modulus and the Poisson's ratio of the rock sample are determined according to the longitudinal wave velocity and the transverse wave velocity of the rock sample, and the elastic brittleness index of the rock sample is determined by normalization according to the Young's modulus and the Poisson's ratio of the rock sample. In an embodiment of the present invention, the longitudinal wave velocity and the transverse wave velocity of the rock sample are determined according to the rock sonic instrument, and the elastic brittleness index of the rock sample is determined by normalization, so as to improve the accuracy of determining the elastic brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0144] Figure 8 The implementation process of step 404 in the tight sandstone reservoir fracturing evaluation method provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0145] In one embodiment of the present invention, in order to improve the accuracy of determining the mineralogical brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), as follows Figure 8 As shown, step 404, using the rock samples of the tight sandstone reservoir, determines the mineralogical brittleness index of the tight sandstone reservoir, including:

[0146] Step 801, analyzing the mineral components of the rock sample by a mineral component analysis method to determine the mass percentage of brittle minerals in the rock sample;

[0147] Step 802, determining the mineralogical brittleness index of the rock sample by normalization according to the mass percentage of brittle minerals in the rock sample.

[0148] The mineralogical brittleness index is mainly used to determine the overall brittleness of the rock by calculating the percentage of brittle minerals. For sandstone reservoirs, since the quartz content and feldspar content in brittle minerals are sometimes slightly different, the mineralogical brittleness index of the rock fragment is determined based on the total amount of quartz and feldspar.

[0149] Specifically, when determining the mineralogical brittleness index of the rock sample, the mineral components of the rock sample are analyzed by a mineral component analysis method to determine the mass percentage of brittle minerals in the rock sample. Among them, the mineral component analysis method includes X-ray diffraction technology and QEMSCAN technology. It can be understood by those skilled in the art that the mineral component analysis method can also include other mineral component analysis methods in addition to the above-mentioned X-ray diffraction technology and QEMSCAN technology, such as EDX and other mineral component analysis methods, and the embodiment of the present invention does not impose any special restrictions on this. Among them, the mineral components of the rock sample mainly include one or more of the following: quartz, feldspar, calcite, dolomite and clay, etc.

[0150] After obtaining the mass percentage of brittle minerals in the rock sample, the mineralogical brittleness index of the rock sample is determined by normalization based on the mass percentage of brittle minerals in the rock sample. The normalization may at least include maximum value normalization.

[0151] Specifically, the normalized mineralogical brittleness index of the rock sample can be obtained by the following maximum normalization method:

[0152]

[0153]

[0154] Among them, B4 represents the mineralogical brittleness index of rock samples, W qua Indicates the mass percentage of quartz, W fel Indicates the mass percentage of feldspar, W calcite Indicates the mass percentage of calcite, W dolomite Indicates the mass percentage of dolomite, W clay represents the mass percentage of clay, a, b, c, d and e represent the correlation coefficients of quartz, feldspar, calcite, dolomite and clay, respectively, which can be obtained through the regression of tight sandstone reservoir; B 4d represents the normalized mineralogy brittleness index of rock fragments, B 4max Indicates the maximum value of the mineralogy brittleness index among the mineralogy brittleness indexes of the rock sample, B 4min It represents the minimum value of the mineralogical brittleness index among the mineralogical brittleness indexes of rock fragments.

[0155] In an embodiment of the present invention, the mineral components of the rock crushed sample are analyzed by a mineral component analysis method to determine the mass percentage of brittle minerals in the rock crushed sample, and the mineralogical brittleness index of the rock crushed sample is determined by normalization according to the mass percentage of brittle minerals in the rock crushed sample. The embodiment of the present invention determines the mass percentage of brittle minerals in the rock crushed sample by a mineral component analysis method, and then determines the mineralogical brittleness index of the rock crushed sample by normalization, which can improve the accuracy of determining the mineralogical brittleness index, and then improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0156] In one embodiment of the present invention, after respectively determining the hardness brittleness index, fracture toughness brittleness index, elastic mechanics brittleness index and mineralogical brittleness index of the tight sandstone reservoir, a comprehensive brittleness evaluation model of the tight sandstone reservoir is established based on the combined weight coefficient, thereby determining the comprehensive fracturing coefficient of the tight sandstone reservoir.

[0157] Specifically, the comprehensive fracturing coefficient of tight sandstone reservoir can be determined by the following formula:

[0158] B=R1B 1d +R2B2d +R3B 3d +R4B 4d ;

[0159] R1+R2+R3+R4=1;

[0160] in,

[0161] B represents the comprehensive fracturing coefficient of tight sandstone reservoir, B 1d , B 2d , B 3d and B 4d They respectively represent the normalized hardness brittleness index, the normalized fracture toughness brittleness index, the normalized elastic mechanics brittleness index and the normalized mineralogical brittleness index. R1, R2, R3 and R4 respectively represent the weight coefficient of the normalized hardness brittleness index, the weight coefficient of the normalized fracture toughness brittleness index, the weight coefficient of the normalized elastic mechanics brittleness index and the weight coefficient of the normalized mineralogical brittleness index.

[0162] The present invention also provides a tight sandstone reservoir evaluation device, as described in the following embodiments. Since the principles of these devices to solve the problem are similar to the tight sandstone reservoir fracturing evaluation method, the implementation of these devices can refer to the implementation of the method, and the repeated parts will not be repeated.

[0163] In the comprehensive brittleness evaluation model, the hardness brittleness index, elastic mechanics brittleness index and mineralogy brittleness index are positive indicators, and the fracture toughness brittleness index is a negative indicator. The positive indicator, that is, the larger the index value, the better, and the negative indicator, that is, the smaller the index value, the better. The range transformation standardization method is used to normalize the quantitative parameters and obtain four evaluation indexes ranging from 0 to 1.

[0164] It should be pointed out that the test order of the experiment must be completed last, so that the entire test result has comparative value. The order of the other three experimental tests, such as micron indentation, micron scratch and ultrasonic test, can be interchanged.

[0165] Fig. 9 The functional modules of the tight sandstone reservoir evaluation device provided by the embodiment of the present invention are shown. For the convenience of description, only the parts related to the embodiment of the present invention are shown, which are described in detail as follows:

[0166] refer to Fig. 9 The modules included in the tight sandstone reservoir evaluation device are used to perform Figure 1 For details of each step in the corresponding embodiment, please refer to Figure 1 as well as Figure 1In the embodiment of the present invention, the tight sandstone reservoir evaluation device includes a fracturing evaluation index determination module 901 , a weight coefficient determination module 902 and a comprehensive fracturability coefficient determination module 903 .

[0167] The fracturing evaluation index determination module 901 is used to determine multiple fracturing evaluation indexes of the tight sandstone reservoir using rock samples of the tight sandstone reservoir.

[0168] The weight coefficient determination module 902 is used to obtain weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs through regression of microseismic and volume fracturing data of fractured wells.

[0169] The comprehensive fracturability coefficient determination module 903 is used to determine the comprehensive fracturability coefficient of the tight sandstone reservoir according to different fracturability evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturability evaluation indicators.

[0170] Among them, the thickness of the rock fragments of the tight sandstone reservoir is not less than the first rock thickness, the length is not less than the first rock length, the width is not less than the first rock width, and more than two rock fragments are collected at the same depth point of the tight sandstone reservoir.

[0171] In the embodiment of the present invention, the fracturing evaluation index determination module 901 uses rock samples of the tight sandstone reservoir to determine multiple fracturing evaluation indexes of the tight sandstone reservoir, the weight coefficient determination module 902 obtains the weight coefficients of multiple fracturing evaluation indexes of the tight sandstone reservoir by regressing the microseismic and volume fracturing data of the fractured well, and the comprehensive fracturability coefficient determination module 903 determines the comprehensive fracturability coefficient of the tight sandstone reservoir according to different fracturing evaluation indexes of the tight sandstone reservoir and the weight coefficients of different fracturing evaluation indexes. The embodiment of the present invention fully considers multiple fracturing evaluation indexes that affect the formation of a complex fracture network in the tight sandstone reservoir, comprehensively considers the multiple fracturing evaluation indexes, and constructs a comprehensive brittleness evaluation model (i.e., comprehensive fracturability coefficient) of the tight sandstone reservoir by combining weights. The comprehensive brittleness evaluation model obtained thereby can better reflect the comprehensive ability of the tight sandstone reservoir to form a complex fracture network during volume fracturing, and has high accuracy and operability.

[0172] Fig.10 Another functional module of the tight sandstone reservoir evaluation device provided by the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0173] In one embodiment of the present invention, in order to further improve the accuracy of determining the comprehensive fracturability coefficient, reference is made to Fig.10 The modules included in the tight sandstone reservoir evaluation device are used to perform Figure 2For details of each step in the corresponding embodiment, please refer to Figure 2 as well as Figure 2 The relevant descriptions in the corresponding embodiments are not repeated here. Fig. 9 Based on the module structure shown, the tight sandstone reservoir evaluation device also includes a preprocessing module 1001.

[0174] The preprocessing module 1001 is used to preprocess the rock samples of the tight sandstone reservoir to obtain the preprocessed rock samples of the tight sandstone reservoir.

[0175] The fracturing evaluation index determination module 901 is also used to determine multiple fracturing evaluation indexes of the tight sandstone reservoir using the pre-processed rock samples of the tight sandstone reservoir.

[0176] In an embodiment of the present invention, the preprocessing module 1001 preprocesses the rock fragments of the tight sandstone reservoir to obtain the preprocessed rock fragments of the tight sandstone reservoir, and uses the preprocessed rock fragments of the tight sandstone reservoir to determine multiple fracturing evaluation indicators of the tight sandstone reservoir, which can further improve the accuracy of determining the comprehensive fracturing coefficient.

[0177] In one embodiment of the present invention, in order to improve the intuitiveness of the degree of fracturing of tight sandstone reservoirs, reference is made to Fig.10 On the basis of the module structure shown above, the tight sandstone reservoir evaluation device further includes a fracturing grade determination module 1002 .

[0178] The fracturability grade determination module 1002 is used to determine the fracturability grade of the tight sandstone reservoir corresponding to the comprehensive fracturability coefficient according to the comprehensive fracturability coefficient of the tight sandstone reservoir.

[0179] In the embodiment of the present invention, the fracturability level determination module 1002 determines the fracturability level of the tight sandstone reservoir corresponding to the comprehensive fracturability coefficient of the tight sandstone reservoir according to the comprehensive fracturability coefficient of the tight sandstone reservoir, which can improve the intuitiveness of the fracturability degree of the tight sandstone reservoir.

[0180] Fig.11 The structure of the pre-processing module 1001 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0181] In one embodiment of the present invention, in order to further improve the accuracy of determining the comprehensive fracturability coefficient, reference is made to Fig.11 The various units included in the preprocessing module 1001 are used to perform Figure 3 For details of each step in the corresponding embodiment, please refer to Figure 3 as well as Figure 3In the embodiment of the present invention, the pre-processing module 1001 includes a cleaning unit 1101 and / or a grinding and polishing unit 1102 .

[0182] The cleaning unit 1101 is used to clean the collected rock fragments using a chemical cleaning agent to obtain the cleaned rock fragments.

[0183] The grinding and polishing unit 1102 is used to grind and polish the collected rock samples by mechanical polishing to obtain the rock samples after grinding and polishing.

[0184] In an embodiment of the present invention, the cleaning unit 1101 uses a chemical cleaning agent to clean the collected rock fragments to obtain cleaned rock fragments, and / or the grinding and polishing unit 1102 uses mechanical polishing to grind and polish the collected rock fragments to obtain polished rock fragments, which can further improve the accuracy of determining the comprehensive fracturability coefficient.

[0185] Fig.12 The structure of the fracturing evaluation index determination module 901 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0186] In one embodiment of the present invention, the multiple fracturing evaluation indicators include at least three of the following four fracturing evaluation indicators: hardness brittleness indicator, fracture toughness brittleness indicator, elastic mechanics brittleness indicator and mineralogy brittleness indicator. In order to comprehensively consider multiple fracturing evaluation indicators that affect the formation of complex fracture networks in tight sandstone reservoirs and improve the comprehensive ability of the comprehensive brittleness evaluation model to reflect the formation of complex fracture networks in tight sandstone reservoirs during volume fracturing, reference is made to Fig.12 The various units included in the fracturing evaluation index determination module 901 are used to perform Figure 4 For details of each step in the corresponding embodiment, please refer to Figure 4 as well as Figure 4 In the embodiment of the present invention, the fracturing evaluation index determination module 901 includes a hardness brittleness index determination unit 1201 , a fracture toughness brittleness index determination unit 1202 , an elastic brittleness index determination unit 1203 and a mineralogy brittleness index determination unit 1204 .

[0187] The hardness and brittleness index determining unit 1201 is used to determine the hardness and brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir.

[0188] The fracture toughness and brittleness index determining unit 1202 is used to determine the fracture toughness and brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir.

[0189] The elastic mechanics brittleness index determining unit 1203 is used to determine the elastic mechanics brittleness index of the tight sandstone reservoir using the rock fragments of the tight sandstone reservoir.

[0190] The mineralogical brittleness index determining unit 1204 is used to determine the mineralogical brittleness index of the tight sandstone reservoir using the rock fragments of the tight sandstone reservoir.

[0191] In an embodiment of the present invention, the hardness and brittleness index determination unit 1201 uses rock samples of tight sandstone reservoirs to determine the hardness and brittleness index of tight sandstone reservoirs, the fracture toughness and brittleness index determination unit 1202 uses rock samples of tight sandstone reservoirs to determine the fracture toughness and brittleness index of tight sandstone reservoirs, and uses rock samples of tight sandstone reservoirs to determine the elastic mechanical brittleness index of tight sandstone reservoirs. The elastic mechanical brittleness index determination unit 1203 uses rock samples of tight sandstone reservoirs to determine the mineralogical brittleness index of tight sandstone reservoirs. The mineralogical brittleness index determination unit 1204 uses three or four evaluation indicators among the above indicators to comprehensively evaluate the fracturing ability of tight sandstone reservoirs, and can comprehensively consider multiple fracturing evaluation indicators that affect the formation of complex fracture networks in tight sandstone reservoirs, thereby improving the comprehensive ability, accuracy and operability of the comprehensive brittleness evaluation model to reflect the formation of complex fracture networks in tight sandstone reservoirs during volume fracturing.

[0192] Fig.13 The structure of the hardness and brittleness index determination unit 1201 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0193] In one embodiment of the present invention, in order to improve the accuracy of determining the hardness brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), reference is made to Fig.13 The subunits included in the hardness and brittleness index determination unit 1201 are used to perform Figure 5 For details of each step in the corresponding embodiment, please refer to Figure 5 as well as Figure 5 In the embodiment of the present invention, the hardness and brittleness index determination unit 1201 includes an indentation test subunit 1301 , a hardness parameter determination subunit 1302 , an average hardness parameter determination subunit 1303 and a hardness and brittleness index determination subunit 1304 .

[0194] The indentation test subunit 1301 is used to perform an indentation test on rock samples of a tight sandstone reservoir by using a micron indentation technique to obtain a load-displacement curve of the indenter on the surface of the rock sample.

[0195] The hardness parameter determination subunit 1302 is used to determine the hardness parameter of the rock sample using the load displacement curve of the indenter on the surface of the rock sample.

[0196] The average hardness parameter determination subunit 1303 is used to determine the average hardness parameter of the rock samples according to the hardness parameters of the rock samples of the tight sandstone reservoir.

[0197] The hardness and brittleness index determination subunit 1304 is used to determine the hardness and brittleness index of the rock fragments by normalization using the average hardness parameter of the rock fragments.

[0198] In the embodiment of the present invention, the indentation test subunit 1301 performs an indentation test on the rock samples of the tight sandstone reservoir by using the micron indentation technology to obtain the load displacement curve of the indenter on the surface of the rock sample, the hardness parameter determination subunit 1302 determines the hardness parameter of the rock sample by using the load displacement curve of the indenter on the surface of the rock sample, the average hardness parameter determination subunit 1303 determines the average hardness parameter of the rock sample according to the hardness parameter of the rock sample of the tight sandstone reservoir, and the hardness brittleness index determination subunit 1304 determines the hardness brittleness index of the rock sample by normalization using the average hardness parameter of the rock sample. In the embodiment of the present invention, the hardness parameter of the rock sample is determined by using the micron indentation technology, and then the hardness brittleness index of the rock sample is determined by normalization, which can improve the accuracy of determining the hardness brittleness index, and then improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0199] Fig.14 The structure of the fracture toughness brittleness index determination unit 1202 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0200] In one embodiment of the present invention, in order to improve the accuracy of determining the fracture toughness brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), reference is made to Fig.14 The fracture toughness brittleness index determination unit 1202 includes various subunits for executing Figure 6 For details of each step in the corresponding embodiment, please refer to Figure 6 as well as Figure 6 In the embodiment of the present invention, the fracture toughness brittleness index determination unit 1202 includes a scratch test subunit 1401 , a fracture toughness determination subunit 1402 , an average fracture toughness determination subunit 1403 and a fracture toughness brittleness index determination subunit 1404 .

[0201] The scratch test subunit 1401 is used to perform a scratch test on rock samples of a tight sandstone reservoir using a micron scratch technique to obtain a friction curve of the indenter on the surface of the rock sample.

[0202] The fracture toughness determination subunit 1402 is used to determine the fracture toughness of the rock sample using the friction curve of the indenter on the surface of the rock sample.

[0203] The average fracture toughness determination subunit 1403 is used to determine the average fracture toughness of the rock samples according to the fracture toughness of the rock samples of the tight sandstone reservoir.

[0204] The fracture toughness and brittleness index determination subunit 1404 is used to determine the fracture toughness and brittleness index of the rock fragments by normalization using the average fracture toughness of the rock fragments.

[0205] In the embodiment of the present invention, the scratch test subunit 1401 performs a scratch test on the rock samples of the tight sandstone reservoir by using the micron scratch technique to obtain the friction curve of the indenter on the surface of the rock sample, the fracture toughness determination subunit 1402 determines the fracture toughness of the rock sample by using the friction curve of the indenter on the surface of the rock sample, the average fracture toughness determination subunit 1403 determines the average fracture toughness of the rock sample according to the fracture toughness of the rock sample of the tight sandstone reservoir, and the fracture toughness brittleness index determination subunit 1404 determines the fracture toughness brittleness index of the rock sample by normalization using the average fracture toughness of the rock sample. The embodiment of the present invention determines the fracture toughness of the rock sample by using the micron scratch test, and then determines the fracture toughness brittleness index of the rock sample by normalization, which can improve the accuracy of determining the fracture toughness brittleness index, and then improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0206] Fig.15 The structure of the elastic brittleness index determination unit 1203 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0207] In one embodiment of the present invention, in order to improve the accuracy of determining the elastic brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), reference is made to Fig.15 The elastic brittleness index determination unit 1203 includes various subunits for executing Figure 7 For details of each step in the corresponding embodiment, please refer to Figure 7 as well as Figure 7In the embodiment of the present invention, the elastic brittleness index determining unit 1203 includes a velocity measuring subunit 1501 , a Young's modulus and Poisson's ratio determining subunit 1502 , and an elastic brittleness index determining subunit 1503 .

[0208] The velocity measurement subunit 1501 is used to measure the longitudinal wave velocity and the transverse wave velocity of the rock sample of the tight sandstone reservoir using a rock sonicator.

[0209] The Young's modulus and Poisson's ratio determination subunit 1502 is used to determine the Young's modulus and Poisson's ratio of the rock fragments according to the longitudinal wave velocity and the transverse wave velocity of the rock fragments.

[0210] The elastic brittleness index determination subunit 1503 is used to determine the elastic brittleness index of the rock fragments by normalization according to the Young's modulus and Poisson's ratio of the rock fragments.

[0211] In the embodiment of the present invention, the velocity measurement subunit 1501 uses a rock sonicator to measure the longitudinal wave velocity and the transverse wave velocity of the rock sample of the tight sandstone reservoir, the Young's modulus and Poisson's ratio determination subunit 1502 determines the Young's modulus and the Poisson's ratio of the rock sample according to the longitudinal wave velocity and the transverse wave velocity of the rock sample, and the elastic brittleness index determination subunit 1503 determines the elastic brittleness index of the rock sample by normalization according to the Young's modulus and the Poisson's ratio of the rock sample. The embodiment of the present invention can improve the accuracy of determining the elastic brittleness index by using a rock sonicator to determine the longitudinal wave velocity and the transverse wave velocity of the rock sample, and then determine the elastic brittleness index of the rock sample by normalization, thereby improving the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0212] Fig.16 The structure of the mineralogical brittleness index determination unit 1204 in the tight sandstone reservoir evaluation device provided in the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0213] In one embodiment of the present invention, in order to improve the accuracy of determining the mineralogical brittleness index, and thus improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient), reference is made to Fig.16 The various units included in the mineralogical brittleness index determination unit 1204 are used to perform Figure 8 For details of each step in the corresponding embodiment, please refer to Figure 8 as well as Figure 8 In the embodiment of the present invention, the mineralogical brittleness index determination unit 1204 includes a mineral component analysis subunit 1601 and a mineralogical brittleness index determination subunit 1602 .

[0214] The mineral component analysis subunit 1601 is used to analyze the mineral components of the rock samples by a mineral component analysis method to determine the mass percentage of brittle minerals in the rock samples.

[0215] The mineralogical brittleness index determination subunit 1602 is used to determine the mineralogical brittleness index of the rock sample by normalization according to the mass percentage of brittle minerals in the rock sample.

[0216] In the embodiment of the present invention, the mineral component analysis subunit 1601 analyzes the mineral components of the rock sample by a mineral component analysis method to determine the mass percentage of brittle minerals in the rock sample, and the mineralogical brittleness index determination subunit 1602 determines the mineralogical brittleness index of the rock sample by normalization based on the mass percentage of brittle minerals in the rock sample. The embodiment of the present invention determines the mass percentage of brittle minerals in the rock sample by a mineral component analysis method, and then determines the mineralogical brittleness index of the rock sample by normalization, which can improve the accuracy of determining the mineralogical brittleness index, and then improve the accuracy of the comprehensive brittleness evaluation model (comprehensive fracturability coefficient).

[0217] The present invention fully considers the comprehensive factors that affect the formation of complex fracture networks in tight sandstone reservoirs, and comprehensively utilizes micron indentation, micron scratch, sonic wave experiments and mineral component analysis results to test the four core factors that may affect the brittleness of tight sandstone rocks: mineralogical characteristics, hardness, fracture toughness and elastic mechanical parameters, and uses a combined weight method to construct a comprehensive brittleness evaluation model for conglomerates. The experimental samples (rock fragments) used in the comprehensive brittleness evaluation model are rich in sources, especially no longer relying on standard uniaxial or triaxial rock mechanics experimental cores, but can be rock fragments or larger drilling cuttings, thereby greatly reducing the difficulty of coring and the requirements for the size of experimental samples. The resulting sandstone brittleness evaluation method has high accuracy and operability, and is of great practical significance for guiding the hydraulic fracturing design and well selection of sandstone reservoirs.

[0218] The present invention provides a method for evaluating the brittleness of tight sandstone reservoirs based on rock sample indentation and scratch experiments. The proposed micron indentation hardness test and micron scratch fracture toughness test methods overcome the defects of existing rock mechanics testing technologies in terms of high requirements on core size and high testing costs, and have high operability and accuracy. In addition, the evaluation method establishes a comprehensive brittleness evaluation model for tight reservoirs from four perspectives, namely, mineralogical characteristics, hardness, fracture toughness and elastic mechanical parameters, thereby providing a new decision-making method for optimizing fracturing layer selection in tight reservoirs.

[0219] Compared with the prior art, the advantages of the present invention are: it takes into account the factors affecting fracturing more comprehensively, establishes a compact reservoir compressibility model from the aspects of mineralogical characteristics, hardness, fracture toughness and elastic mechanical parameters, makes up for the inadequacy of the existing evaluation methods in considering this factor, and better reflects the comprehensive ability to distinguish the complex fracture network formed in compact reservoirs during volume fracturing. Secondly, the micron scratch and micron indentation technology is introduced to test the mechanical properties of rocks, and the acoustic wave data and the experimental results of the rock mineral components are effectively combined to facilitate parallel experimental analysis, especially reducing the dependence on the size of standard rock samples; the compact sandstone reservoir brittleness evaluation method based on rock sample indentation and scratch experiments has a high practical value and can be used to quickly evaluate the quality of compact reservoirs at different levels of fracturing wells.

[0220] An embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned tight sandstone reservoir fracturing evaluation method when executing the computer program.

[0221] An embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the above-mentioned tight sandstone reservoir fracturing evaluation method.

[0222] In summary, in the embodiment of the present invention, a rock sample of a tight sandstone reservoir is used to determine a plurality of fracturing evaluation indicators of the tight sandstone reservoir, and the weight coefficients of the plurality of fracturing evaluation indicators of the tight sandstone reservoir are obtained by regressing the microseismic and volume fracturing data of the fractured wells, and the comprehensive fracturing coefficient of the tight sandstone reservoir is determined according to the different fracturing evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturing evaluation indicators. The embodiment of the present invention fully considers a plurality of fracturing evaluation indicators that affect the formation of a complex fracture network in the tight sandstone reservoir, comprehensively considers the plurality of fracturing evaluation indicators, and constructs a comprehensive brittleness evaluation model (i.e., comprehensive fracturing coefficient) of the tight sandstone reservoir by combining weights, and the comprehensive brittleness evaluation model thus obtained can better reflect the comprehensive ability of the tight sandstone reservoir to form a complex fracture network during volume fracturing, and has high accuracy and operability.

[0223] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0224] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0225] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0226] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0227] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating tight sandstone reservoir fracturing, characterized in that: include: Using rock samples from tight sandstone reservoirs, multiple fracturing evaluation indicators of tight sandstone reservoirs are determined; The thickness of the rock sample of the tight sandstone reservoir is not less than the first rock thickness, the length is not less than the first rock length, the width is not less than the first rock width, and more than two rock samples are collected at the same depth point of the tight sandstone reservoir; Multiple fracturing evaluation indicators include: hardness brittleness index, fracture toughness brittleness index, elastic mechanics brittleness index and mineralogy brittleness index; The weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs are obtained through regression of microseismic and volume fracturing data of fractured wells. According to different fracturing evaluation indexes of tight sandstone reservoirs and weight coefficients of different fracturing evaluation indexes, the comprehensive fracturing coefficient of tight sandstone reservoirs is determined; Among them, using the rock samples of the tight sandstone reservoir, multiple fracturing evaluation indicators of the tight sandstone reservoir are determined, including: using the rock samples of the tight sandstone reservoir, determining the hardness brittleness index of the tight sandstone reservoir; using the rock samples of the tight sandstone reservoir, determining the fracture toughness brittleness index of the tight sandstone reservoir; using the rock samples of the tight sandstone reservoir, determining the elastic mechanical brittleness index of the tight sandstone reservoir; using the rock samples of the tight sandstone reservoir, determining the mineralogical brittleness index of the tight sandstone reservoir; Among them, the rock samples of tight sandstone reservoirs are used to determine the hardness and brittleness indicators of tight sandstone reservoirs, including: The indentation test is carried out on the rock samples of the tight sandstone reservoir by using the micron indentation technology to obtain the load displacement curve of the indenter on the surface of the rock sample; the test indentation depth is at least higher than 3000nm; The hardness parameter of the rock sample is determined by the following formula using the load displacement curve of the indenter on the surface of the rock sample: Where H1 represents the hardness parameter of the rock sample, P max Indicates the maximum load, A c represents the contact projection area under the corresponding load, h c Denotes the contact depth, h max represents the total penetration depth, v E represents the Poisson's ratio of the rock sample, ε represents a constant related to the pressure head, and S represents the contact stiffness of the system; Determine the average hardness parameter of the rock crushed sample according to the hardness parameter of the rock crushed sample of the tight sandstone reservoir; The hardness and brittleness index of the rock samples are determined by using the average hardness parameter of the rock samples and the maximum value normalization. Among them, the rock samples of tight sandstone reservoirs are used to determine the fracture toughness and brittleness indicators of tight sandstone reservoirs, including: The micron scratch test was carried out on the rock samples of the tight sandstone reservoir to obtain the friction curve of the indenter on the surface of the rock sample. The fracture toughness of the rock sample is determined by the following formula using the friction curve of the indenter on the surface of the rock sample: Among them, K c represents the fracture toughness of the rock sample, G represents the strain energy release rate, E represents the Young's modulus of the rock sample, v represents the Poisson's ratio of the rock sample, and F T represents the tangential force, 2pA represents the shape function of the indenter, p represents the circumference of the contact part between the indenter and the material in the x-axis direction, A represents the projected area of ​​the contact part between the indenter and the material in the x-axis direction, and F eq Expressed with tangential force F T and the vertical force F v When the angle between the axis of the pressure head and the vertical axis is equal to 0, F eq =F T , d represents the scratch depth, tangential force F T The scratch depth d is obtained through the scratch test, and q represents the half apex angle of the indenter; Determine the average fracture toughness of rock fragments according to the fracture toughness of rock fragments of tight sandstone reservoir; The average fracture toughness of the rock samples is used to determine the fracture toughness brittleness index of the rock samples through maximum value normalization. Among them, the rock samples of tight sandstone reservoirs are used to determine the mineralogical brittleness indicators of tight sandstone reservoirs, including: Analyze the mineral components of the rock samples by using the mineral component analysis method to determine the mass percentage of brittle minerals in the rock samples; According to the mass percentage of brittle minerals in the rock sample, the mineralogical brittleness index of the rock sample is determined by the following maximum value normalization: Among them, B4 represents the mineralogical brittleness index of rock samples, W qua Indicates the mass percentage of quartz, W fel Indicates the mass percentage of feldspar, W calcite Indicates the mass percentage of calcite, W dolomite Indicates the mass percentage of dolomite, W clay represents the mass percentage of clay, a, b, c, d and e represent the correlation coefficients of quartz, feldspar, calcite, dolomite and clay, respectively, which are obtained through the regression of tight sandstone reservoir; B 4d represents the normalized mineralogy brittleness index of rock fragments, B 4max Indicates the maximum value of the mineralogy brittleness index among the mineralogy brittleness indexes of the rock sample, B 4min It represents the minimum value of the mineralogical brittleness index among the mineralogical brittleness indexes of rock fragments.

2. The method for evaluating tight sandstone reservoir fracturing according to claim 1, characterized in that: Also includes: Pre-processing the rock crushed samples of the tight sandstone reservoir to obtain the pre-processed rock crushed samples of the tight sandstone reservoir; Using rock samples of tight sandstone reservoirs, multiple fracturing evaluation indicators of tight sandstone reservoirs are determined, including: Using the pre-treated rock samples of the tight sandstone reservoir, multiple fracturing evaluation indices of the tight sandstone reservoir are determined.

3. The method for evaluating tight sandstone reservoir fracturing according to claim 2, characterized in that: Pre-processing the rock samples of the tight sandstone reservoir to obtain the pre-processed rock samples of the tight sandstone reservoir, including: Using a chemical cleaning agent to clean the collected rock fragments to obtain cleaned rock fragments; and / or The collected rock fragments are ground and polished by mechanical polishing to obtain the ground and polished rock fragments.

4. The method for evaluating tight sandstone reservoir fracturing according to claim 1, characterized in that: Also includes: According to the comprehensive fracturing coefficient of the tight sandstone reservoir, the fracturing grade of the tight sandstone reservoir corresponding to the comprehensive fracturing coefficient is determined.

5. The method for evaluating tight sandstone reservoir fracturing according to claim 1, characterized in that: Using rock samples of tight sandstone reservoirs, the elastic mechanical brittleness indicators of tight sandstone reservoirs are determined, including: The rock sonic instrument is used to measure the P-wave velocity and S-wave velocity of the rock fragments in the tight sandstone reservoir. According to the longitudinal wave velocity and transverse wave velocity of the rock sample, the Young's modulus and Poisson's ratio of the rock sample are determined respectively; According to the Young's modulus and Poisson's ratio of the rock fragments, the elastic brittleness index of the rock fragments is determined by normalization.

6. A tight sandstone reservoir evaluation device, characterized in that: include: A fracturing evaluation index determination module is used to determine multiple fracturing evaluation indexes of the tight sandstone reservoir using rock samples of the tight sandstone reservoir; The thickness of the rock sample of the tight sandstone reservoir is not less than the first rock thickness, the length is not less than the first rock length, the width is not less than the first rock width, and more than two rock samples are collected at the same depth point of the tight sandstone reservoir; Multiple fracturing evaluation indicators include: hardness brittleness index, fracture toughness brittleness index, elastic mechanics brittleness index and mineralogy brittleness index; A weight coefficient determination module is used to obtain weight coefficients of multiple fracturing evaluation indicators of tight sandstone reservoirs through regression of microseismic and volume fracturing data of fractured wells; A comprehensive fracturing coefficient determination module is used to determine the comprehensive fracturing coefficient of the tight sandstone reservoir according to different fracturing evaluation indicators of the tight sandstone reservoir and the weight coefficients of the different fracturing evaluation indicators; The fracturing evaluation index determination module includes: a hardness brittleness index determination unit, which is used to determine the hardness brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir; a fracture toughness brittleness index determination unit, which is used to determine the fracture toughness brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir; an elastic mechanics brittleness index determination unit, which is used to determine the elastic mechanics brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir; a mineralogy brittleness index determination unit, which is used to determine the mineralogy brittleness index of the tight sandstone reservoir using the rock samples of the tight sandstone reservoir; The hardness and brittleness index determination unit includes: The indentation test subunit is used to perform indentation tests on rock samples of tight sandstone reservoirs using micron indentation technology to obtain the load-displacement curve of the indenter on the surface of the rock sample; the test indentation depth is at least higher than 3000nm; The hardness parameter determination subunit is used to determine the hardness parameter of the rock sample by using the load displacement curve of the indenter on the surface of the rock sample through the following formula: Where H1 represents the hardness parameter of the rock sample, P max Indicates the maximum load, A c represents the contact projection area under the corresponding load, h c Denotes the contact depth, h max represents the total penetration depth, v E represents the Poisson's ratio of the rock sample, ε represents a constant related to the pressure head, and S represents the contact stiffness of the system; The average hardness parameter determination subunit is used to determine the average hardness parameter of the rock sample according to the hardness parameter of the rock sample of the tight sandstone reservoir; The hardness and brittleness index determination subunit is used to determine the hardness and brittleness index of the rock sample by using the average hardness parameter of the rock sample and by maximum value normalization; The fracture toughness brittleness index determination unit includes: The scratch test subunit is used to perform scratch tests on rock samples of tight sandstone reservoirs using micron scratch technology to obtain the friction curve of the indenter on the surface of the rock sample; The fracture toughness determination subunit is used to determine the fracture toughness of the rock sample by using the friction curve of the indenter on the surface of the rock sample through the following formula: Among them, K c represents the fracture toughness of the rock sample, G represents the strain energy release rate, E represents the Young's modulus of the rock sample, v represents the Poisson's ratio of the rock sample, and F T represents the tangential force, 2pA represents the shape function of the indenter, p represents the circumference of the contact part between the indenter and the material in the x-axis direction, A represents the projected area of ​​the contact part between the indenter and the material in the x-axis direction, and F eq Expressed with tangential force F T and the vertical force F v When the angle between the axis of the pressure head and the vertical axis is equal to 0, F eq =F T , d represents the scratch depth, tangential force F T The scratch depth d is obtained through the scratch test, and q represents the half apex angle of the indenter; An average fracture toughness determination subunit is used to determine the average fracture toughness of rock fragments according to the fracture toughness of rock fragments of the tight sandstone reservoir; The fracture toughness and brittleness index determination subunit is used to determine the fracture toughness and brittleness index of the rock fragments by using the average fracture toughness of the rock fragments and by maximum value normalization; The mineralogical brittleness index determination unit includes: The mineral component analysis subunit is used to analyze the mineral components of the rock samples by the mineral component analysis method to determine the mass percentage of brittle minerals in the rock samples; The mineralogical brittleness index determination subunit is used to determine the mineralogical brittleness index of the rock sample according to the mass percentage of brittle minerals in the rock sample by the following maximum value normalization: Among them, B4 represents the mineralogical brittleness index of rock samples, W qua Indicates the mass percentage of quartz, W fel Indicates the mass percentage of feldspar, W calcite Indicates the mass percentage of calcite, W dolomite Indicates the mass percentage of dolomite, W clay represents the mass percentage of clay, a, b, c, d and e represent the correlation coefficients of quartz, feldspar, calcite, dolomite and clay, respectively, which are obtained through the regression of tight sandstone reservoir; B 4d represents the normalized mineralogy brittleness index of rock fragments, B 4max Indicates the maximum value of the mineralogy brittleness index among the mineralogy brittleness indexes of the rock sample, B 4min It represents the minimum value of the mineralogical brittleness index among the mineralogical brittleness indexes of rock fragments.

7. The tight sandstone reservoir evaluation device according to claim 6, characterized in that: Also includes: A preprocessing module is used to preprocess the rock fragments of the tight sandstone reservoir to obtain the preprocessed rock fragments of the tight sandstone reservoir; The fracturing evaluation index determination module is also used to determine multiple fracturing evaluation indexes of the tight sandstone reservoir using the pre-processed rock samples of the tight sandstone reservoir.

8. The tight sandstone reservoir evaluation device according to claim 7, characterized in that: The preprocessing modules include: A cleaning unit, used to clean the collected rock samples using a chemical cleaning agent to obtain cleaned rock samples; and / or The grinding and polishing unit is used for grinding and polishing the collected rock fragments by mechanical polishing to obtain the ground and polished rock fragments.

9. The tight sandstone reservoir evaluation device according to claim 6, characterized in that: Also includes: The fracturing grade determination module is used to determine the fracturing grade of the tight sandstone reservoir corresponding to the comprehensive fracturing coefficient according to the comprehensive fracturing coefficient of the tight sandstone reservoir.

10. The tight sandstone reservoir evaluation device according to claim 6, characterized in that: The elastic brittleness index determination unit includes: The velocity measurement subunit is used to measure the longitudinal wave velocity and the transverse wave velocity of the rock sample of the tight sandstone reservoir using a rock sonic instrument; The Young's modulus and Poisson's ratio determination subunit is used to determine the Young's modulus and Poisson's ratio of the rock fragments according to the longitudinal wave velocity and the transverse wave velocity of the rock fragments; The elastic brittleness index determination subunit is used to determine the elastic brittleness index of the rock fragments by normalization based on the Young's modulus and Poisson's ratio of the rock fragments.

11. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the tight sandstone reservoir fracturing evaluation method according to any one of claims 1 to 5 is implemented.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for executing the tight sandstone reservoir fracturing evaluation method according to any one of claims 1 to 5.

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