Single well crack identification method based on rock mechanics and ground stress bidirectional constraint

Abstract

The invention discloses a single well crack identification method based on rock mechanics and ground stress bidirectional constraint, and the method comprises the steps: obtaining and analyzing coring well data, special logging data and conventional logging data of a research region, and calculating a rock mechanics parameter and a ground stress parameter according to a conventional logging curve; determining a fracture development index, a horizontal stress difference and a stress heterogeneity coefficient of a fracture development characterization part of the rock mechanics layer and the ground stress layer; comparing the fracture development index, the horizontal stress difference and the stress heterogeneous coefficient with the single-well fracture characteristic parameter and the fracture development part characteristic parameter to obtain a fracture development part parameter fluctuation interval; according to the parameter fluctuation interval of the fracture development part, performing fluctuation interval screening on the well of which the single-well fracture development part needs to be predicted; and a comprehensive crack identification curve is constructed according to the screened fluctuation intervals, and the single-well crack development part is predicted, so that the single-well crack identification precision is improved.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas geological exploration and development, and in particular to a single well fracture identification method based on bidirectional constraints of rock mechanics and geostress. Background Art

[0002] Accurate and efficient identification and prediction of reservoir fractures have always been the focus of research in oilfield exploration and development. Common reservoir fracture prediction methods include: using cores to accurately identify and characterize small-scale fractures in the reservoir, using imaging logging data to intuitively identify single well fractures and extract and analyze fracture data, introducing a variety of mathematical methods to amplify the abnormal response of conventional logging curves in the development of small and medium-scale fractures, and using a variety of seismic attribute technologies to identify and predict large-scale fractures. However, due to the relatively small amount of core data, the expensive deployment of imaging logging, and the large scale of seismic methods, a comprehensive analysis shows that conventional logging, which has the advantages of easy acquisition, low cost, and simple processing, is the most important research direction for single well fracture identification and characterization.

[0003] The patent document with publication number: CN106526693A discloses a fracture identification method and device, which obtains fracture data of a study area; determines the development characteristics of fractures and the distribution law of fractures in the study area based on the fracture data; establishes an electrical identification standard for lithology and classifies various lithologies; extracts fracture characteristic parameters of various lithologies based on logging curves; establishes a fracture nonlinear identification model based on the fracture characteristic parameters and obtains fracture identification results of a single well in the study area based on the model; determines a three-dimensional model of fracture strength in the study area based on the fracture identification results of the single well in combination with production dynamic data, fracture development characteristics and fracture distribution laws.

[0004] The patent document with publication number: CN111781638A discloses a method for predicting effective fracture zones. The method determines the development range of the effective fracture zone in a single well by identifying effective fractures and classifying the effective fracture types; analyzes the differences caused by effective fractures on the physical properties of the formation rock, and establishes an intersection diagram of different rock physical properties. The physical properties used to distinguish different fracture zones are screened out based on the intersection diagram; a Bayesian discriminant method is used to establish a discriminant formula for the effective fracture zone based on the physical properties; a three-dimensional data body of the distinguishing physical properties of the formation to be tested is obtained, and the effective fracture zone is distinguished in three dimensions in combination with the discriminant formula to obtain the spatial distribution of the effective fracture zone.

[0005] The patent with publication number: CN110320569B discloses a method for quantitatively evaluating the intensity of fracture development in a single well in a tight sandstone reservoir, which comprises determining characteristic parameters for fracture identification in a single well in the reservoir; determining comprehensive indication parameters of fractures in the single well to be evaluated based on the characteristic parameters for fracture identification in the single well in the reservoir, and quantitatively identifying the fracture layer of the single well to be evaluated based on the comprehensive indication parameters of fractures in the single well; determining the intensity index of fracture development in the single well to be evaluated, and quantitatively evaluating the intensity of fracture development in the single well to be evaluated based on the intensity index of fracture development in the single well.

[0006] The patent with publication number: CN104360415B discloses a method for identifying fractures in tight sandstone reservoirs. By analyzing the relationship between characteristic parameters of single-well fracture logging responses, relevant characteristic parameters for single-well fracture identification are established, and then the weighted arithmetic average method is used to construct a fracture comprehensive evaluation model parameter - a fracture comprehensive index. The method can identify fractures in tight sandstone reservoir sections where single-well fractures are to be identified by analyzing the size of the fracture comprehensive index. The method for identifying fractures in tight sandstone reservoirs can accurately and reliably identify fractured sections, providing a basis for the rational and effective development of tight sandstone oil and gas reservoirs.

[0007] However, currently, when using logging curves to identify and characterize single well fractures, most of them start with the response characteristics of various types of curves to the location of fracture development using mathematical methods, while ignoring the fact that when there are cracks in the rock, its own rock mechanical properties and ground stress disturbance phenomena will obviously deviate from the original formation, resulting in low identification accuracy. Summary of the invention

[0008] To this end, the present application provides a single well fracture identification method based on rock mechanics and geostress bidirectional constraints to solve the problem of low identification accuracy of single well fracture identification methods in the prior art.

[0009] In order to achieve the above objectives, this application provides the following technical solutions:

[0010] In the first aspect, a single well fracture identification method based on rock mechanics and geostress bidirectional constraints comprises:

[0011] Step 1: Obtain core well data, special logging data and conventional logging data in the study area;

[0012] Step 2: determining the single well fracture characteristic parameters according to the coring well data;

[0013] Step 3: determining characteristic parameters of fracture development locations according to the special logging data;

[0014] Step 4: obtaining a conventional logging curve according to the conventional logging data;

[0015] Step 5: Calculate rock mechanical parameters according to the conventional logging curve, and determine the fracture development index that characterizes the fracture development position at the rock mechanical level;

[0016] Step 6: Calculate the geostress parameters according to the conventional logging curve, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress level characterizing the fracture development location;

[0017] Step 7: Compare the fracture development index, the horizontal stress difference and the stress heterogeneity coefficient with the single well fracture characteristic parameters and the fracture development location characteristic parameters to obtain the fracture development location parameter fluctuation range;

[0018] Step 8: screening the wells for which single-well fracture development locations need to be predicted according to the fluctuation range of the fracture development location parameter;

[0019] Step 9: Construct a comprehensive fracture identification curve based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and predict the fracture development location of a single well.

[0020] Preferably, in step 2, the single well fracture characteristic parameters include fracture development location, depth and fracture length data.

[0021] Preferably, in step 3, the special logging includes imaging logging and dipole shear wave logging.

[0022] Preferably, in step 4, the conventional logging curves include acoustic wave time difference curves, density curves and caliper curves.

[0023] Preferably, in step 5, when calculating rock mechanical parameters according to the conventional logging curve, if the dipole shear wave logging exists in the study area and the available shear wave logging curve of the target layer can be collected, firstly, the longitudinal wave logging curve is calculated based on the shear wave logging curve using the longitudinal and shear wave conversion formula, and then the Young's modulus and Poisson's ratio in the rock mechanical parameters are calculated using the longitudinal wave time difference and the shear wave time difference, and finally the fracture development index is calculated based on the Young's modulus and the Poisson's ratio.

[0024] Preferably, if the dipole shear wave logging exists in the study area, but the available shear wave logging curve of the target layer cannot be collected or the collected shear wave logging curve is unusable, it is necessary to construct a correlation fitting curve based on the existing shear wave logging curve and the acoustic wave time difference curve, so as to convert the conventional logging curve into a shear wave time difference curve, and then calculate the compressional wave time difference curve.

[0025] Preferably, in step 6, the horizontal stress difference and the stress heterogeneity coefficient are calculated based on the Poisson's ratio and the three-dimensional geostress of a single well.

[0026] Preferably, in step 9, three comprehensive crack identification curves need to be constructed.

[0027] In a second aspect, a single well fracture identification device based on rock mechanics and ground stress bidirectional constraints comprises:

[0028] Data acquisition module, used to obtain core well data, special logging data and conventional logging data in the study area;

[0029] A coring well data analysis module, used to determine single well fracture characteristic parameters based on the coring well data;

[0030] A special logging data analysis module, used to determine characteristic parameters of fracture development locations based on the special logging data;

[0031] A conventional logging data analysis module, used for obtaining a conventional logging curve according to the conventional logging data;

[0032] A rock mechanics parameter calculation module, used to calculate rock mechanics parameters according to the conventional logging curve, and determine a fracture development index characterizing fracture development locations at the rock mechanics level;

[0033] A geostress parameter calculation module, used to calculate geostress parameters according to the conventional logging curve, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress layer characterizing the fracture development position;

[0034] A fluctuation range determination module is used to compare the fracture development index, the horizontal stress difference and the stress heterogeneity coefficient with the single well fracture characteristic parameters and the fracture development site characteristic parameters to obtain a fracture development site parameter fluctuation range;

[0035] A fluctuation interval screening module is used to screen the fluctuation interval of the wells for which the single well fracture development location needs to be predicted according to the fluctuation interval of the fracture development location parameter;

[0036] The single well fracture development location prediction module is used to construct a comprehensive fracture identification curve based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and predict the single well fracture development location.

[0037] In a third aspect, a computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a single well fracture identification method based on bidirectional constraints of rock mechanics and geostress are implemented.

[0038] Compared with the prior art, this application has at least the following beneficial effects:

[0039] The present application provides a single well fracture identification method based on rock mechanics and geostress bidirectional constraints. The method obtains core well data, special logging data and conventional logging data in a study area, and determines the fracture characteristic parameters of a single well, fracture development site characteristic parameters and conventional logging curves. The rock mechanics parameters and geostress parameters are calculated according to the conventional logging curves, and the fracture development index, horizontal stress difference and stress heterogeneity coefficient that characterize the fracture development site at the rock mechanics level and geostress level are determined; the fracture development index, horizontal stress difference and stress heterogeneity coefficient are compared with the fracture characteristic parameters of a single well and the fracture development site characteristic parameters to obtain the fluctuation range of the fracture development site parameters; the fluctuation range of the wells for which the fracture development site of a single well needs to be predicted is screened according to the fluctuation range of the fracture development site parameters; a comprehensive fracture identification curve is constructed according to the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and the fracture development site of a single well is predicted. The present application starts with the rock mechanical properties and ground stress disturbance phenomenon when cracks exist in the rock, and predicts the location of fracture development in a single well, thereby greatly reducing the error caused by using mathematical methods to study the response of various types of curves at the location of fracture development, and improving the accuracy of single well fracture identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, those skilled in the art are capable of easily making conventional adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components) based on the technical concepts and exemplary drawings disclosed in the present application.

[0041] Figure 1 A flow chart of a single well fracture identification method based on rock mechanics and geostress bidirectional constraints provided in Example 1 of the present application;

[0042] Figure 2 A schematic diagram of screening results of the fracture development index, horizontal stress difference and stress heterogeneity coefficient provided in Example 1 of the present application;

[0043] Figure 3 A schematic diagram of predicting the location of fracture development in a single well provided in Example 1 of the present application. DETAILED DESCRIPTION

[0044] The present application is further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0045] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0046] The terms such as "upper", "lower", "left", "right", "middle", etc. cited in this application are usually used to indicate the general relative position relationship for the purpose of intuitive understanding by referring to the drawings, and are not absolute limitations on the position relationship in the actual product.

[0047] Embodiment 1

[0048] See also Figure 1 This embodiment provides a single well fracture identification method based on rock mechanics and ground stress bidirectional constraints, including:

[0049] S1: Obtain core well data, special logging data and conventional logging data in the study area;

[0050] Specifically, a coring well refers to a well that is used to extract rock cores from underground during geological exploration. The coring well data includes data such as the distribution of coring wells, coring intervals, coring yield, and core length.

[0051] S2: Determine the fracture characteristic parameters of a single well based on the coring well data;

[0052] Specifically, this step identifies the fracture characteristic parameters of a single well by coring the well. Since the goal of this embodiment is to predict the fracture development location, it is only necessary to count the fracture development location, depth and fracture length information when identifying the fracture characteristic parameters of a single well, so as to accurately locate the influence range of the fracture in the vertical direction of the single well.

[0053] S3: Determine the characteristic parameters of the fracture development location based on special logging data;

[0054] This step identifies the characteristic parameters of the fracture development location by analyzing special logging data and performs statistical analysis. Specifically, the special logging in this embodiment includes two types: imaging logging and dipole shear wave logging. Among them, the collection of imaging logging needs to pay attention to the collection of dynamic and static images and FVDC curves. The dynamic and static images are used for researchers to observe the fracture development location, depth and fracture length information with the naked eye, and the FVDC curve is used to verify the accuracy of artificial fracture identification. Dipole shear wave logging needs to collect the collected shear wave logging curves as the data basis for rock mechanics and ground stress calculations.

[0055] S4: obtaining conventional logging curves according to conventional logging data;

[0056] Conventional logging is commonly used in actual oilfield exploration and development. Therefore, the collection of conventional logging curves is relatively simple, but it should be noted that when collecting conventional logging curves, AC (acoustic time difference curve), DEN (density curve) and CAL (well diameter curve) must be included. Some wells also lack DEN (density curve), so at least AC (acoustic time difference curve) and CAL (well diameter curve) must be included.

[0057] For conventional logging, it is easy to have unconverted units due to replacement of test equipment or multiple sampling. In this case, the unit of the same type of logging curve in the target layer needs to be standardized and corrected before subsequent calculations. There may also be large sections of logging data lost or data anomalies caused by engineering accidents such as well leakage and well collapse. In this case, the well section needs to be standardized and set to 0 or a maximum value to avoid the abnormal data of the well section affecting the subsequent calculation results.

[0058] S5: Calculate rock mechanical parameters based on conventional logging curves and determine the fracture development index (FI) that characterizes the fracture development location at the rock mechanical level;

[0059] Specifically, when calculating rock mechanical parameters based on the well logging curves in the study area, it should be noted that when there is dipole shear wave logging in the study area and the available shear wave logging curves of the target layer can be collected, the longitudinal and shear wave conversion formula is first used to calculate the longitudinal wave logging curve based on the shear wave logging curve. The longitudinal and shear wave conversion formula is:

[0060]

[0061] In the above formula, Δtc and Δts represent the longitudinal wave time difference and the transverse wave time difference respectively, and the unit is μ s / f t (microseconds / foot); ρ b Indicates the volume density of rock in g / cm 3 .

[0062] After conversion, the Young's modulus (E) and Poisson's ratio (σ) in rock mechanics parameters are calculated using the time difference between longitudinal and transverse waves. The calculation formulas for the two are:

[0063]

[0064] In the above formula, E is the dynamic Young's modulus calculated by well logging, in MPa; σ is Poisson's ratio, dimensionless.

[0065] Finally, the fracture development index (FI) based on Young's modulus (E) and Poisson's ratio (σ) is constructed to characterize the fracture development location at the rock mechanics level:

[0066]

[0067] In the above formula, E ma is the elastic modulus of the rock skeleton and is a constant when the lithology is the same.

[0068] When dipole shear wave logging exists in the study area, but the available shear wave logging curve of the target layer cannot be collected or the collected shear wave logging curve is unusable, it is necessary to construct a correlation fitting curve based on the existing shear wave logging curve and the conventional logging curve AC (acoustic wave time difference curve), so as to convert the conventional logging curve AC (acoustic wave time difference curve) into a shear wave time difference curve, and then calculate the compressional wave time difference curve.

[0069] S6: Calculate the geostress parameters based on conventional logging curves, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress layer representing the fracture development location;

[0070] Specifically, after calculating the rock mechanical parameters through the logging curve, the Poisson's ratio σ is used to calculate the three-dimensional ground stress of a single well. The calculation formula is:

[0071]

[0072] In the above formula, σ V represents vertical stress in MPa; H represents burial depth (m); ρ(z) represents rock density at burial depth z, which can be obtained from density logging data; σ H is the maximum horizontal principal stress, in MPa; σ h represents the minimum horizontal principal stress, in MPa; ω1 and ω2 represent the horizontal stress coefficients; α represents the Biot coefficient; σ represents the Poisson's ratio; P P Indicates pore pressure, unit: MPa.

[0073] It should be noted that the horizontal geostress coefficients ω1 and ω2, as well as the Biot coefficient α, need to be determined based on the actual conditions of the study area.

[0074] Then, based on the calculation results of the three-dimensional geostress, the horizontal stress difference (S) and stress heterogeneity coefficient (Y) are constructed to characterize the crack development location at the geostress level:

[0075] S=σ1-σ3

[0076] Y=σ1 / σ3.

[0077] S7: Compare the fracture development index, horizontal stress difference and stress heterogeneity coefficient with the single well fracture characteristic parameters and fracture development location characteristic parameters to obtain the fluctuation range of fracture development location parameters;

[0078] Specifically, in this step, the fracture development index (FI) calculated by the rock mechanics parameters (Young's modulus E and Poisson's ratio σ) and the horizontal stress difference (S) and stress heterogeneity coefficient (Y) curves calculated by the ground stress parameters are compared with the fracture development locations statistically obtained by coring wells and imaging logging, so as to determine the data fluctuation range of the rock mechanics level at the fracture development location.

[0079] It should be noted that the wells currently used to study rock mechanics parameters, determine the fracture development index (FI) of the parameters characterizing the fracture development location at the rock mechanics level, study geostress parameters, determine the horizontal stress difference (S) and stress heterogeneity coefficient (Y) of the parameters characterizing the fracture development location at the geostress level, should be wells that have both core sampling of the target layer and imaging logging information or only core sampling of the target layer and imaging logging information. The role of these wells is to statistically analyze the fluctuation range of various parameters at the fracture development location, and to prepare data for fracture prediction in single wells that do not have core sampling of the target layer and imaging logging information.

[0080] S8: screening the wells for which the single-well fracture development location needs to be predicted according to the fluctuation range of the parameters of the fracture development location;

[0081] Specifically, this step screens the fluctuation range of the wells whose single well fracture development locations need to be predicted based on the fluctuation range of the parameters of the fracture development index (FI), horizontal stress difference (S) and stress heterogeneity coefficient (Y) at the fracture development location.

[0082] More specifically, in this step, after the fracture development index (FI), horizontal stress difference (S) and stress heterogeneity coefficient (Y) in the parameter fluctuation range of the fracture development part are determined for the wells with core sampling of the target layer section and imaging logging information or only with core sampling of the target layer section and imaging logging information, the fracture development index (FI), horizontal stress difference (S) and stress heterogeneity coefficient (Y) are calculated for the wells whose fracture development parts of the single wells need to be predicted, and then the fracture development parts of the single wells need to be predicted are screened out through the fracture development index (FI), horizontal stress difference (S) and stress heterogeneity coefficient (Y) in the parameter fluctuation range of the fracture development part.

[0083] S9: A comprehensive fracture identification curve is constructed based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and the fracture development location of a single well is predicted.

[0084] Specifically, since the response of a single fracture development index (FI), horizontal stress difference (S) and stress heterogeneity coefficient (Y) to fractures is accidental, the prediction accuracy can be further improved by considering the three curves comprehensively. To this end, a comprehensive fracture identification curve (Z) is constructed to predict the development location of fractures in a comprehensive single well:

[0085] Z=FI*S*Y

[0086] After normalizing the comprehensive crack identification curve (Z), it can better reflect the crack development location:

[0087]

[0088] In order to more clearly illustrate a single well fracture identification method based on rock mechanics and geostress bidirectional constraints provided by this embodiment, this embodiment provides a specific example:

[0089] First, by investigating the distribution of coring wells in the study area, mastering the coring layer section, coring recovery rate and core length data of each coring well, identifying and counting the characteristic parameters of single well fractures in each coring well, and accurately locating the influence range of fractures in the vertical direction of the single well. Secondly, collecting imaging logging data in special logging in the study area, especially collecting dynamic and static images in special logging, so as to observe the fracture development location, depth and fracture length information of single wells containing special logging, and make up for the deficiency of less coring in the target layer section of the coring well, and improve the accuracy of artificial fracture identification by collecting FVDC curves in special logging. Finally, collecting conventional logging data of coring wells and wells to be predicted, ensuring that at least AC (acoustic time difference curve) and CAL (well diameter curve) are contained, and all conventional logging curves are standardized for subsequent calculation and identification of fracture development locations in single wells. It should also be noted that according to the actual situation in the study area, dipole shear wave logging in special logging should be collected to facilitate subsequent calculation and identification of fracture development locations in single wells.

[0090] After the preliminary operation is completed, the logging curve is used to calculate the rock mechanical parameters according to the method provided in this embodiment to determine the fracture development index (FI) of the parameter characterizing the fracture development location at the rock mechanical level, and the logging curve is used to calculate the ground stress parameters to determine the parameters characterizing the fracture development location at the ground stress level, the horizontal stress difference (S) and the stress heterogeneity coefficient (Y). By comparing the three-parameter curve with the fracture development location of the coring well and the imaging logging statistics, the data fluctuation range of the rock mechanical level at the fracture development location can be determined. After statistics on the fluctuation range of the parameters of the fracture development position of the fracture development index (FI), it is found that the fracture development index (FI) has three fracture development ranges, and the values ​​are distributed in: 0.493-0.563, 0.593-0.603 and 0.663-0.673; the horizontal stress difference (S) has four fracture development ranges, and the values ​​are distributed in: 35.567-35.812, 36.057-36.302, 37.282-37.527 and 39.977-40.712; the stress heterogeneity coefficient (Y) has two fracture development ranges, and the values ​​are distributed in: 1.407-1.4105 and 1.4315-1.163, such as Figure 2After constructing the comprehensive fracture identification curve (Z) using the fracture development intervals of the three parameters, the comprehensive single-well fracture development location prediction can be performed, as shown in Figure 3 shown.

[0091] The present embodiment provides a single well fracture identification method based on rock mechanics and geostress bidirectional constraints. Based on the statistical analysis results of core and special logging fractures in the study area, the conventional logging curve is used to calculate the rock mechanics and geostress parameters. The parameter fluctuation range of the fracture development position is clarified, and the rock mechanics and geostress parameters of the single well to be predicted are screened using the parameter fluctuation range. A comprehensive fracture identification curve is constructed with two-way constraints, and then the fracture development position of the single well is predicted. This method solves the problem that when using logging curves to identify and characterize reservoir fractures, mathematical methods are often used to start from the response characteristics of various types of curves to the fracture development position, while ignoring the fact that when there are fractures in the rock, its own rock mechanics properties and geostress disturbance phenomenon will obviously deviate from the original formation, resulting in limited identification accuracy, thereby improving the accuracy of single well fracture identification.

[0092] This embodiment starts with the rock mechanical properties and ground stress disturbance phenomenon when cracks exist in the rock, and predicts the location of crack development in a single well, thereby greatly reducing the error caused by using mathematical methods to study the response of various types of curves at the location of crack development, improving the accuracy of single well crack identification, and providing a set of effective solutions for professionals who predict the location of crack development in a single well.

[0093] Embodiment 2

[0094] This embodiment provides a single well fracture identification device based on rock mechanics and ground stress bidirectional constraints, including:

[0095] Data acquisition module, used to obtain core well data, special logging data and conventional logging data in the study area;

[0096] A coring well data analysis module, used to determine single well fracture characteristic parameters based on the coring well data;

[0097] A special logging data analysis module, used to determine characteristic parameters of fracture development locations based on the special logging data;

[0098] A conventional logging data analysis module, used for obtaining a conventional logging curve according to the conventional logging data;

[0099] A rock mechanics parameter calculation module, used to calculate rock mechanics parameters according to the conventional logging curve, and determine a fracture development index characterizing fracture development locations at the rock mechanics level;

[0100] A geostress parameter calculation module, used to calculate geostress parameters according to the conventional logging curve, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress layer characterizing the fracture development position;

[0101] A fluctuation range determination module is used to compare the fracture development index, the horizontal stress difference and the stress heterogeneity coefficient with the single well fracture characteristic parameters and the fracture development site characteristic parameters to obtain a fracture development site parameter fluctuation range;

[0102] A fluctuation interval screening module is used to screen the fluctuation interval of the wells for which the single well fracture development location needs to be predicted according to the fluctuation interval of the fracture development location parameter;

[0103] The single well fracture development location prediction module is used to construct a comprehensive fracture identification curve based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and predict the single well fracture development location.

[0104] For the specific implementation content of each module in a single well fracture identification device based on rock mechanics and geostress bidirectional constraints, please refer to the above definition of a single well fracture identification method based on rock mechanics and geostress bidirectional constraints, which will not be repeated here.

[0105] Embodiment 3

[0106] This embodiment provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, steps of a single well fracture identification method based on bidirectional constraints of rock mechanics and geostress are implemented.

[0107] The technical features of the above embodiments may be arbitrarily combined (as long as there is no contradiction in the combination of these technical features). To make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A single well fracture identification method based on rock mechanics and geostress bidirectional constraints, characterized in that: include: Step 1: Obtain core well data, special logging data and conventional logging data in the study area; Step 2: determining the single well fracture characteristic parameters according to the coring well data; Step 3: determining characteristic parameters of fracture development locations according to the special logging data; Step 4: obtaining a conventional logging curve according to the conventional logging data; Step 5: Calculate rock mechanical parameters according to the conventional logging curve, and determine the fracture development index that characterizes the fracture development position at the rock mechanical level; Step 6: Calculate the geostress parameters according to the conventional logging curve, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress level characterizing the fracture development location; Step 7: Compare the fracture development index, the horizontal stress difference and the stress heterogeneity coefficient with the single well fracture characteristic parameters and the fracture development location characteristic parameters to obtain the fracture development location parameter fluctuation range; Step 8: screening the wells for which single-well fracture development locations need to be predicted according to the fluctuation range of the fracture development location parameter; Step 9: Construct a comprehensive fracture identification curve based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and predict the fracture development location of a single well.

2. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 1 is characterized in that: In step 2, the single well fracture characteristic parameters include fracture development location, depth and fracture length data.

3. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 1 is characterized in that: In step 3, the special logging includes imaging logging and dipole shear wave logging.

4. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 3 is characterized in that: In step 4, the conventional logging curves include acoustic wave time difference curves, density curves and wellbore curves.

5. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 4 is characterized in that: In step 5, when calculating rock mechanical parameters according to the conventional logging curve, if the dipole shear wave logging exists in the study area and the available shear wave logging curve of the target layer can be collected, firstly, the longitudinal wave logging curve is calculated based on the shear wave logging curve using the longitudinal and shear wave conversion formula, and then the Young's modulus and Poisson's ratio in the rock mechanical parameters are calculated using the longitudinal wave time difference and the shear wave time difference, and finally the fracture development index is calculated based on the Young's modulus and the Poisson's ratio.

6. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 5 is characterized in that: If the dipole shear wave logging exists in the study area, but the available shear wave logging curve of the target layer cannot be collected or the collected shear wave logging curve is unusable, it is necessary to construct a correlation fitting curve based on the existing shear wave logging curve and the acoustic wave time difference curve, so as to convert the conventional logging curve into a shear wave time difference curve, and then calculate the compressional wave time difference curve.

7. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 5, characterized in that: In step 6, the horizontal stress difference and the stress heterogeneity coefficient are calculated based on the Poisson's ratio and the three-dimensional geostress of a single well.

8. The single well fracture identification method based on rock mechanics and geostress bidirectional constraints according to claim 1, characterized in that: In step 9, three comprehensive crack identification curves need to be constructed.

9. A single well fracture identification device based on rock mechanics and geostress bidirectional constraints, characterized in that: include: Data acquisition module, used to obtain core well data, special logging data and conventional logging data in the study area; A coring well data analysis module, used to determine single well fracture characteristic parameters based on the coring well data; A special logging data analysis module, used to determine characteristic parameters of fracture development locations based on the special logging data; A conventional logging data analysis module, used for obtaining a conventional logging curve according to the conventional logging data; A rock mechanics parameter calculation module, used to calculate rock mechanics parameters according to the conventional logging curve, and determine a fracture development index characterizing fracture development locations at the rock mechanics level; A geostress parameter calculation module, used to calculate geostress parameters according to the conventional logging curve, and determine the horizontal stress difference and stress heterogeneity coefficient of the geostress layer characterizing the fracture development position; A fluctuation range determination module is used to compare the fracture development index, the horizontal stress difference and the stress heterogeneity coefficient with the single well fracture characteristic parameters and the fracture development site characteristic parameters to obtain a fracture development site parameter fluctuation range; A fluctuation interval screening module is used to screen the fluctuation interval of the wells for which the single well fracture development location needs to be predicted according to the fluctuation interval of the fracture development location parameter; The single well fracture development location prediction module is used to construct a comprehensive fracture identification curve based on the screened fracture development index, horizontal stress difference and stress heterogeneity coefficient, and predict the single well fracture development location.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

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