Coal rock longitudinal wave anisotropy coefficient logging determination method, device and equipment

Abstract

The invention discloses a coal rock longitudinal wave anisotropy coefficient logging determination method, device and equipment, and the method comprises the steps: obtaining the continuous depth vitrinite reflectivity of coal rock based on a logging curve of the coal rock; and determining the continuous depth longitudinal wave anisotropy coefficient of the coal rock according to the continuous depth vitrinite reflectance of the coal rock and the incidence relation between the longitudinal wave anisotropy coefficient of the core sample of the coal rock and the vitrinite reflectance of the core sample, which is pre-constructed based on an experimental analysis method. According to the method, aiming at the problem of coal rock stratum longitudinal wave anisotropy evaluation, the function relation between the longitudinal wave anisotropy coefficient and the vitrinite reflectivity is creatively established through anisotropy cause analysis, and then logging information is used for continuous deep processing, so that the coal rock longitudinal wave anisotropy coefficient logging calculation method is formed. The method provided by the invention mainly aims at a coal rock stratum, and can provide necessary parameters for coal rock anisotropy characteristic analysis, crustal stress calculation and the like.

Description

Technical Field

[0001] This invention relates to the field of logging data processing, interpretation and evaluation technology in oil and gas exploration and development, and particularly to a method, apparatus and equipment for determining the longitudinal wave anisotropy coefficient of coal and rock in logging. Background Technology

[0002] Natural gas is a high-quality, efficient, green, and clean low-carbon energy source, and there is a need to find alternative resources on a large scale. Deep coalbed methane is expected to become an important source of natural gas supply, thereby driving a major transformation in the natural gas industry structure.

[0004] Compared to shallow to medium-depth coalbed methane, deep coalbed methane reservoirs exhibit more complex geological conditions, characterized by high temperature and pressure, complex pore structure, and strong heterogeneity. The pore space includes matrix pores as well as fractures and cleavages, resulting in extremely strong acoustic anisotropy. Acoustic anisotropy refers to the directional characteristic of acoustic wave velocity in rocks; that is, measurements taken along different directions yield different results. Due to this anisotropy, significant errors can occur when using geophysical information to invert and interpret formation parameters. Therefore, accurate evaluation of acoustic anisotropy is crucial.

[0005] Acoustic anisotropy includes longitudinal wave anisotropy and transverse wave anisotropy, and is usually characterized by the difference in acoustic wave velocity in two mutually perpendicular directions. The numerical values ​​of these differences are collectively referred to as the anisotropy coefficient. Methods for evaluating acoustic anisotropy coefficients mainly fall into two categories. One category involves experimentally measuring the longitudinal and transverse wave velocities in different directions and calculating the differences between these velocities. This method requires coring, is expensive, and time-consuming, making it unsuitable for large-scale applications. The other category involves evaluation using well logging data. In vertical wells, conventional acoustic logging can obtain the longitudinal and transverse wave velocities in the vertical direction. For transverse wave anisotropy, the Stoneley wave inversion method can be used to obtain the transverse wave velocity in the horizontal direction, thereby determining the transverse wave anisotropy coefficient. Summary of the Invention

[0006] In order to enable low-cost, continuous-depth evaluation of the P-wave anisotropy coefficient of coal and rock, thereby enriching technical approaches and increasing the selection space, this invention provides a method, apparatus, and equipment for determining the P-wave anisotropy coefficient of coal and rock through well logging.

[0007] In a first aspect, embodiments of the present invention provide a method for determining the longitudinal wave anisotropy coefficient of coal and rock through well logging, which may include:

[0008] Based on the well logging curves of the coal and rock, the continuous depth vitrinite reflectance of the coal and rock is obtained;

[0009] The longitudinal wave anisotropy coefficient of the coal and rock is determined by the continuous depth vitrinite reflectance of the coal and rock, and the correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of the core sample of the coal and rock, which is pre-constructed based on experimental analysis methods.

[0010] In one embodiment, obtaining the continuous depth vitrinite reflectance of the coal and rock based on the well logging curve may include:

[0011] The correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance.

[0012] The least squares method is used to fit the well logging sensitivity curve and the measured vitrinite reflectance to construct the continuous depth vitrinite reflectance expression of the coal and rock.

[0013] Based on the expression for the continuous depth vitrinite reflectance of the coal and rock and the well logging sensitivity curve, the continuous depth vitrinite reflectance of the coal and rock is obtained.

[0014] In another embodiment, the step of screening the logging sensitive curves with high correlation to the measured vitrinite reflectance from the logging curves using the correlation coefficient method may include:

[0015] The Pearson correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance.

[0016] Among them, the selected logging sensitive curves include: deep resistivity logging curve, sonic transit time logging curve, neutron logging curve and density logging curve.

[0017] In another embodiment, the correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of the coal core sample is pre-constructed using the following method:

[0018] Two rock samples with different orientations were drilled from the core sample of the coal and rock.

[0019] The longitudinal wave velocity of rock samples in different directions was measured, as well as the bulk density and vitrinite reflectance of the core samples.

[0020] Based on the bulk density of the core sample and the longitudinal wave velocity of the rock sample in different directions, the longitudinal wave anisotropy coefficient of the core sample is determined.

[0021] Based on the longitudinal wave anisotropy coefficient and vitrinite reflectance of multiple core samples of the coal and rock, a correlation between the longitudinal wave anisotropy coefficient and vitrinite reflectance of the core samples is constructed.

[0022] In another embodiment, drilling two core samples from the coal and rock rock in different directions may include:

[0023] Vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction were drilled from the core sample.

[0024] In another embodiment, the vitrinite reflectance of the core sample is determined by the following method:

[0025] Sample preparation involves mixing epoxy resin and the powder of the core sample, drying at 60°C for 12–16 hours, and then grinding and polishing the dried sample to prepare the test sample.

[0026] For sample determination, 0.03g of the test sample was prepared into a cylindrical shape, the surface was polished, and the vitrinite reflectance of the core sample was measured using the oil immersion and photomultiplier tube methods. Two reflectance standard plates were used for calibration, and the vitrinite reflectance of the core sample was determined by comparison.

[0027] Secondly, embodiments of the present invention provide a detailed method for determining the longitudinal wave anisotropy coefficient of coal and rock through well logging, which may include:

[0028] Vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction were drilled from the core samples of coal and rock.

[0029] The longitudinal wave velocity of the vertical rock sample and the horizontal rock sample were measured respectively, as well as the bulk density and vitrinite reflectance of the core sample.

[0030] The longitudinal wave anisotropy coefficient of the core sample is determined based on the longitudinal wave velocity of the vertical and horizontal rock samples and the bulk density of the core sample.

[0031] Based on the longitudinal wave anisotropy coefficient and vitrinite reflectance of multiple core samples of the coal and rock, a correlation between the longitudinal wave anisotropy coefficient and vitrinite reflectance of the core samples based on experimental analysis methods is constructed.

[0032] Based on the well logging curves of the coal and rock, the continuous depth vitrinite reflectance of the coal and rock is obtained;

[0033] The longitudinal wave anisotropy coefficient of the coal and rock is determined by the continuous depth vitrinite reflectance of the coal and rock, and the correlation between the longitudinal wave anisotropy coefficient of the coal and rock core sample and the vitrinite reflectance of the core sample constructed based on experimental analysis methods.

[0034] Thirdly, embodiments of the present invention provide a logging device for determining the longitudinal wave anisotropy coefficient of coal and rock, which may include:

[0035] The acquisition module is used to acquire the continuous depth vitrinite reflectance of the coal and rock based on the well logging curves of the coal and rock.

[0036] The determination module is used to determine the longitudinal wave anisotropy coefficient of the coal rock at continuous depth using the vitrinite reflectance of the coal rock at continuous depth and the correlation between the longitudinal wave anisotropy coefficient of the coal rock core sample and the vitrinite reflectance of the core sample, which is pre-constructed based on experimental analysis methods.

[0037] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the coal and rock longitudinal wave anisotropy coefficient during logging as described in the first aspect.

[0038] Fifthly, embodiments of the present invention provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining the coal and rock longitudinal wave anisotropy coefficient in well logging as described in the first aspect.

[0039] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0040] This invention provides a method, apparatus, and equipment for determining the P-wave anisotropy coefficient in coal and rock formations through well logging. Addressing the challenge of evaluating P-wave anisotropy in coal and rock formations, this method innovatively establishes a functional relationship between the P-wave anisotropy coefficient and vitrinite reflectivity through anisotropy origin analysis. Then, by processing continuous depth well logging data, a well logging calculation method for the P-wave anisotropy coefficient in coal and rock formations is formed. The method provided in this invention primarily targets coal and rock formations and can provide necessary parameters for coal and rock anisotropy characteristic analysis and geostress calculation.

[0041] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0043] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0044] Figure 1 This is a flowchart of the method for determining the longitudinal wave anisotropy coefficient of coal and rock in well logging provided in this embodiment of the invention;

[0045] Figure 2This is a flowchart illustrating the method for constructing the correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of a coal core sample, as provided in this embodiment of the invention.

[0046] Figure 3 This is a schematic diagram of the core drilling direction provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of core sound velocity measurement provided in an embodiment of the present invention;

[0048] Figure 5 A schematic diagram illustrating the physical meaning of the stiffness coefficient in the generalized Hooke's Law.

[0049] Figure 6 This is a cross-plot of vitrinite reflectivity and longitudinal wave anisotropy coefficient provided in an embodiment of the present invention;

[0050] Figure 7 This is a schematic diagram of the well logging device for determining the longitudinal wave anisotropy coefficient of coal and rock provided in an embodiment of the present invention;

[0051] Figure 8 This is a flowchart of a detailed method for determining the longitudinal wave anisotropy coefficient of coal and rock in well logging, provided in an embodiment of the present invention.

[0052] Figure 9 This is a diagram showing the results of continuous depth processing of the longitudinal wave anisotropy coefficient provided in an embodiment of the present invention. Detailed Implementation

[0053] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0054] In practical work, the inventors have found that there is still no good method for evaluating P-wave anisotropy. Therefore, how to evaluate the P-wave anisotropy coefficient of coal and rock at low cost and continuous depth is a pressing problem that needs to be solved. In view of the above problems, this invention is proposed to provide a method, apparatus, and equipment for determining the P-wave anisotropy coefficient of coal and rock through well logging that overcomes or at least partially solves the above problems.

[0055] Example 1

[0056] Embodiment 1 of this invention provides a method for determining the P-wave anisotropy coefficient of coal and rock through well logging, referring to... Figure 1 As shown, the method may include the following steps:

[0057] Step S11: Based on the well logging curves of coal and rock, obtain the continuous depth vitrinite reflectance of coal and rock.

[0058] Step S12: Determine the longitudinal wave anisotropy coefficient of coal and rock at continuous depth using the vitrinite reflectance of the coal and rock and the correlation between the longitudinal wave anisotropy coefficient of the coal and rock core sample and the vitrinite reflectance of the core sample, which is pre-constructed based on experimental analysis methods.

[0059] The well logging method for determining the P-wave anisotropy coefficient of coal and rock formations provided in this embodiment of the invention addresses the challenge of evaluating the P-wave anisotropy of coal and rock formations. Through anisotropy origin analysis, it innovatively establishes a functional relationship between the P-wave anisotropy coefficient and vitrinite reflectivity. Then, by utilizing continuous depth processing of well logging data, a well logging calculation method for the P-wave anisotropy coefficient of coal and rock formations is formed. The method provided in this embodiment of the invention is mainly aimed at coal and rock formations and can provide necessary parameters for coal and rock anisotropy characteristic analysis and geostress calculation.

[0060] In one embodiment, refer to Figure 2 As shown, the correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of the coal core samples was pre-constructed using the following method:

[0061] Step S21: Drill two core samples from the coal and rock sampler, each with a different orientation. In this step, core samples are taken from the outcrop or the full-diameter borehole. It should be noted that the two different orientations are preferably perpendicular to each other. They can be perpendicular to the coal and rock bedding, or they can be at a certain angle. If a certain angle is used during sampling, the calculation of the P-wave anisotropy coefficient will need to be performed using that angle.

[0062] In this step, for ease of subsequent calculations, this embodiment drills both vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction. (Refer to...) Figure 3 The diagram illustrates the core drilling direction in an embodiment of the present invention. Two smaller cores are drilled from a large core, such as a full-diameter core or an outcrop. The size of the smaller cores is sufficient for rock elastic property experiments. The two smaller cores are drilled in two ways: one perpendicular to the bedding planes and the other parallel to the bedding planes.

[0063] Step S22: Measure the longitudinal wave velocity of rock samples from different directions. (Refer to...) Figure 4 As shown, in this step, the P-wave velocity of vertical and horizontal rock samples is measured using an instrument. The P-wave velocity of the vertical rock core is denoted as V. PV The longitudinal wave velocity of the horizontal core is denoted as V. PH .

[0064] Step S23: Measure the bulk density and vitrinite reflectance of the core sample. In this step, the bulk density and vitrinite reflectance of the core sample are measured using an instrument.

[0065] Step S24: Determine the longitudinal wave anisotropy coefficient of the core sample based on the bulk density of the core sample and the longitudinal wave velocity of the rock sample in different directions.

[0066] Combination Figure 5 As shown, in this step, the P-wave anisotropy coefficient of the core sample is calculated using Thomson's characterization method for P-wave anisotropy coefficient. The formula is as follows:

[0067] in,

[0068] The generalized Hooke's law provides the following physical meaning for the stiffness coefficient:

[0069]

[0070] In the formula, ε is the longitudinal wave anisotropy coefficient; ρ is the bulk density of the core sample; combined with Figure 5 The generalized Hooke's law shown above, C ij (i and j = 1, 2, 3, 4, 5, 6) are stiffness coefficients. Different coefficients form a stiffness coefficient matrix, used to characterize the elastic properties of rocks. i and j represent the stress surface and the direction of the force, respectively. In practical applications, let xx = 1, yy = 2, zz = 3, yz = 4, xz = 5, xy = 6, and let C... 12 For example, the first 1 represents xx, and the second 2 represents yy. By solving the Christoffel equation, we can find the values ​​of different C. ij The relationship with V, such as

[0071] Step S25: Based on the longitudinal wave anisotropy coefficients and vitrinite reflectance of multiple coal and rock core samples, construct the correlation between the longitudinal wave anisotropy coefficients and vitrinite reflectance of the coal and rock core samples.

[0072] In this step, the relationship between the P-wave anisotropy coefficient and the vitrinite reflectivity is established by using the P-wave anisotropy coefficient calculated from the experimentally measured P-wave velocities and bulk densities of core samples from different directions, and the corresponding experimentally analyzed vitrinite reflectivity to establish a functional relationship. The characterization formula can be: ε=a·ln(R o )+b;

[0073] Where a and b are empirical coefficients, R o Spectral reflectance; reference Figure 6As shown, the cross plot of vitrinite reflectance and P-wave anisotropy coefficient is constructed by experimentally testing several different core samples. The horizontal axis represents vitrinite reflectance, scaled from 0 to 3; the vertical axis represents the P-wave anisotropy coefficient, scaled from 0 to 0.6. The P-wave anisotropy coefficient increases non-linearly with increasing vitrinite reflectance. Then, the above correlation (characterization formula) is obtained by fitting the data. o )+b.

[0074] In another optional embodiment, the vitrinite reflectance is obtained using a vitrinite reflectance measurement method. Vitrinite reflectance is an important indicator of organic matter maturity, used to characterize the thermal evolution of organic matter from early diagenesis to deep metamorphic stages. The inventors discovered a correlation between maturity and the P-wave anisotropy coefficient, and further characterized the P-wave anisotropy coefficient through maturity. The vitrinite reflectance measurement method in this embodiment includes sample preparation and measurement processes. The vitrinite reflectance of the core sample is determined using the following method:

[0075] First, sample preparation involved mixing epoxy resin and core sample powder, drying at 60°C for 12–16 hours, and then grinding and polishing to prepare the test sample. Next, sample measurement involved taking 0.03 g of the test sample, forming it into a cylindrical shape, polishing the surface, and measuring the vitrinite reflectance using oil immersion and photomultiplier tube methods. Two reflectance standard plates were used for calibration, and the vitrinite reflectance of the core sample was determined by comparison.

[0076] In another optional embodiment, the vitrinite reflectance is obtained by processing well logging data using a conventional well logging curve fitting method to evaluate vitrinite reflectance at continuous depth. The process of obtaining the continuous depth vitrinite reflectance of coal and rock in step S11 above may specifically include the following steps:

[0077] Step S111: Use the correlation coefficient method to screen the logging curves that are highly correlated with the measured vitrinite reflectance.

[0078] In this step, the Pearson correlation coefficient method is used to screen logging curves that have a high correlation with the measured vitrinite reflectivity. The selected logging curves may include: deep resistivity logging curves, sonic transit time logging curves, neutron logging curves, and density logging curves.

[0079] In a specific example, the formula for calculating the Pearson correlation coefficient is as follows:

[0080]

[0081] In the formula, ρ X,Yσ is the Pearson correlation coefficient, cov is the covariance, σ is the standard deviation, and X and Y are two types of data, namely vitrinite reflectance and well logging curves.

[0082] Step S112: Use the least squares method to fit the well logging sensitivity curve and the measured vitrinite reflectance to construct an expression for the continuous depth vitrinite reflectance of coal and rock.

[0083] In this step, the expression for the continuous depth vitrinite reflectance of coal and rock is constructed by performing a least-squares fit based on the relationship between the measured vitrinite reflectance and the well logging sensitivity curve, thereby realizing the continuous depth calculation of vitrinite reflectance. One such expression is:

[0084] R o =c+d·RD+e·AC+f·CNL+g·DEN

[0085] In the formula, R o denoted as vitrinite reflectivity, RD as deep resistivity, AC as acoustic transit time, CNL as neutron density, DEN as density, and c, d, e, f, and g are empirical coefficients.

[0086] Step S113: Based on the expression for the continuous depth vitrinite reflectance of coal and rock and the well logging sensitivity curve, obtain the continuous depth vitrinite reflectance of coal and rock.

[0087] In this step, the continuous depth evaluation of the P-wave anisotropy coefficient is achieved by processing well logging data to obtain the vitrinite reflectivity at continuous depths. The P-wave anisotropy coefficient can then be calculated using the functional relationship between the P-wave anisotropy coefficient and the vitrinite reflectivity. The functional relationship between the P-wave anisotropy coefficient and the vitrinite reflectivity is as follows:

[0088] ε 测井 =a·ln(R) o测井 )+b

[0089] The above method innovatively establishes a functional relationship between the P-wave anisotropy coefficient and vitrinite reflectivity through anisotropic origin analysis. Then, by using continuous depth processing of well logging data, a continuous depth evaluation method for the P-wave anisotropy coefficient of coal and rock is formed. This invention is mainly aimed at coal and rock formations and can provide necessary parameters for coal and rock anisotropy characteristic analysis and geostress calculation.

[0090] Based on the same inventive concept, this invention also provides a well logging device for determining the longitudinal wave anisotropy coefficient of coal and rock, referring to... Figure 7 As shown, the device may include an acquisition module 71 and a determination module 72, and its working principle is as follows:

[0091] The acquisition module 71 is used to acquire the continuous depth vitrinite reflectance of coal and rock based on the well logging curves of coal and rock.

[0092] The determination module 72 is used to determine the longitudinal wave anisotropy coefficient of coal and rock at continuous depth using the vitrinite reflectance of coal and rock and the correlation between the longitudinal wave anisotropy coefficient of coal and rock core samples and the vitrinite reflectance of core samples, which is pre-constructed based on experimental analysis methods.

[0093] In an optional embodiment, the acquisition module 71 is specifically used for:

[0094] The correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance.

[0095] The least squares method is used to fit the well logging sensitivity curve and the measured vitrinite reflectance to construct the continuous depth vitrinite reflectance expression of the coal and rock.

[0096] Based on the expression for the continuous depth vitrinite reflectance of the coal and rock and the well logging sensitivity curve, the continuous depth vitrinite reflectance of the coal and rock is obtained.

[0097] In another alternative embodiment, the acquisition module 71 may further be used for:

[0098] The Pearson correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance.

[0099] Among them, the selected logging sensitive curves include: deep resistivity logging curve, sonic transit time logging curve, neutron logging curve and density logging curve.

[0100] Based on the same inventive concept, this embodiment of the invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-mentioned method for determining the anisotropy coefficient of coal and rock longitudinal waves in well logging.

[0101] Based on the same inventive concept, this embodiment of the invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned method for determining the anisotropy coefficient of coal and rock longitudinal waves in well logging.

[0102] The principles by which the above-mentioned devices, media, and related equipment in the embodiments of the present invention solve the problem are similar to those of the aforementioned methods. Therefore, their implementation can refer to the implementation of the aforementioned methods, and repeated details will not be repeated.

[0103] Example 2

[0104] Embodiment 2 of the present invention also provides a detailed method for determining the P-wave anisotropy coefficient of coal and rock through well logging, referring to... Figure 8 As shown, the method may include the following steps:

[0105] Step S81: Drill vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction from the core samples of coal and rock.

[0106] Step S82: Measure the longitudinal wave velocity of the vertical rock sample and the horizontal rock sample respectively.

[0107] Step S83: Measure the bulk density of the core sample.

[0108] Step S84: Measure the vitrinite reflectance of the core sample.

[0109] It should be noted that steps S83 and S84 can be performed directly after obtaining the core sample, or after measuring the longitudinal wave velocity of the vertical and horizontal rock samples in step S82. Step S84 can be performed after step S85. This embodiment of the invention does not specifically limit this.

[0110] Step S85: Determine the longitudinal wave anisotropy coefficient of the core sample based on the longitudinal wave velocity of the vertical and horizontal rock samples and the bulk density of the core sample.

[0111] Step S86: Based on the longitudinal wave anisotropy coefficient and vitrinite reflectance of multiple core samples of coal and rock, construct the correlation between the longitudinal wave anisotropy coefficient and vitrinite reflectance of core samples based on experimental analysis methods.

[0112] Step S87: Based on the well logging curves of the coal and rock, obtain the continuous depth vitrinite reflectance of the coal and rock. It should be noted that step S87 in this embodiment of the invention can be executed after step S86 or before step S81, as long as it is executed before step S88, which determines the continuous depth P-wave anisotropy coefficient of the coal and rock. This embodiment of the invention does not specifically limit this.

[0113] Step S88: Determine the longitudinal wave anisotropy coefficient of coal and rock at continuous depth using the vitrinite reflectance of the coal and rock and the correlation between the longitudinal wave anisotropy coefficient of the coal and rock core sample and the vitrinite reflectance of the core sample constructed based on experimental analysis methods.

[0114] In a specific example, the above method may include the following steps:

[0115] 1. Core sampling from different directions

[0116] like Figure 3 As shown, full-diameter core samples were taken from an unconventional reservoir in an oil field, and samples were taken perpendicular to and parallel to the bedding planes. A small core with a diameter of 25 mm and a length of 50 mm was drilled, which were defined as vertical rock samples and horizontal rock samples.

[0117] 2. Measure the bulk density and P-wave velocity of core samples from different directions.

[0118] like Figure 4 As shown, the bulk density ρ of different core samples was measured, and the longitudinal wave velocity of vertical and horizontal samples was measured respectively.

[0119] 3. Calculate the anisotropy coefficient of the longitudinal wave.

[0120] The longitudinal wave anisotropy coefficient of the core was calculated using the Thomson formula.

[0121] 4. Measure the vitrinite reflectance of the rock core.

[0122] Measuring the vitrinite reflectance of rock cores

[0123] 5. Establish the relationship between the longitudinal wave anisotropy coefficient and the vitrinite reflectivity.

[0124] The longitudinal wave anisotropy coefficient and vitrinite reflectivity are obtained through measurements in steps 3 and 4. The functional relationship between them is established using the least squares method, such as... Figure 6 As shown, the correlation coefficient is as high as 0.98, and the empirical formula is:

[0125] ε=0.25·ln(R o +0.25

[0126] 6. Well logging data processing to obtain vitrinite reflectivity

[0127] like Figure 9 As shown, the reflectivity of vitrinite is calculated using continuous depth data from well logging.

[0128] 7. Evaluation of Longitudinal Wave Anisotropy Coefficient at Continuous Depth

[0129] like Figure 9 As shown, the vitrinite reflectivity obtained from well logging data processing is used to evaluate the P-wave anisotropy coefficient at continuous depth. (Refer to...) Figure 9As shown, the first channel is the lithology indicator channel, with the solid line representing the conventional natural gamma curve, which primarily characterizes lithological variations. The second channel is the depth channel, indicating the distance from the wellhead to the measurement section (i.e., the target layer). The third channel is the logging profile channel, representing the lithology identification results from cuttings logging. The fourth channel is the three porosity curve channel, with the dashed line representing the compensated neutron curve (CNL), the solid line representing the acoustic transit time curve (AC), and the dotted line representing the bulk density curve (DEN). All three curves can be used to calculate porosity, characterizing the formation's physical properties. The fifth channel is the resistivity curve channel, with the solid line representing the deep lateral resistivity curve (RD) and the dotted line representing the shallow lateral resistivity curve (RS). The resistivity curve primarily characterizes the electrical conductivity of the formation rocks, thereby evaluating formation lithology, fluid properties, etc. The sixth channel is the vitrinite reflectance channel, with the solid line representing the vitrinite reflectance (Ro) calculated using CNL, AC, DEN, and RD. The seventh channel is the longitudinal wave anisotropy coefficient channel, and the dotted line represents the longitudinal wave anisotropy coefficient calculated from the vitrinite reflectivity.

[0130] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0131] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0132] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0133] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0134] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for determining the longitudinal wave anisotropy coefficient of coal and rock through well logging, characterized in that, include: Based on the well logging curves of the coal and rock, the continuous depth vitrinite reflectance of the coal and rock is obtained; The longitudinal wave anisotropy coefficient of the coal and rock is determined by the continuous depth vitrinite reflectance of the coal and rock, and the correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of the core sample of the coal and rock, which is pre-constructed based on experimental analysis methods.

2. The method according to claim 1, characterized in that, The well logging curve based on coal and rock, which obtains the continuous depth vitrinite reflectance of the coal and rock, includes: The correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance. The least squares method is used to fit the well logging sensitivity curve and the measured vitrinite reflectance to construct the continuous depth vitrinite reflectance expression of the coal and rock. Based on the expression for the continuous depth vitrinite reflectance of the coal and rock and the well logging sensitivity curve, the continuous depth vitrinite reflectance of the coal and rock is obtained.

3. The method according to claim 2, characterized in that, The step of screening the logging sensitive curves with high correlation to the measured vitrinite reflectance from the logging curves using the correlation coefficient method includes: The Pearson correlation coefficient method was used to screen the logging curves that showed a high correlation with the measured vitrinite reflectance. Among them, the selected logging sensitive curves include: deep resistivity logging curve, sonic transit time logging curve, neutron logging curve and density logging curve.

4. The method according to any one of claims 1 to 3, characterized in that, The correlation between the longitudinal wave anisotropy coefficient and the vitrinite reflectance of the coal core sample was pre-constructed using the following method: Two rock samples with different orientations were drilled from the core sample of the coal and rock. The longitudinal wave velocity of rock samples in different directions was measured, as well as the bulk density and vitrinite reflectance of the core samples. Based on the bulk density of the core sample and the longitudinal wave velocity of the rock sample in different directions, the longitudinal wave anisotropy coefficient of the core sample is determined. Based on the longitudinal wave anisotropy coefficient and vitrinite reflectance of multiple core samples of the coal and rock, a correlation between the longitudinal wave anisotropy coefficient and vitrinite reflectance of the core samples is constructed.

5. The method according to claim 4, characterized in that, The drilling of two core samples from coal and rock at different angles includes: Vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction were drilled from the core sample.

6. The method according to claim 4, characterized in that, The vitrinite reflectance of the core sample was determined by the following method: Sample preparation involves mixing epoxy resin and the powder of the core sample, drying at 60°C for 12–16 hours, and then grinding and polishing the dried sample to prepare the test sample. For sample determination, 0.03g of the test sample was prepared into a cylindrical shape, the surface was polished, and the vitrinite reflectance of the core sample was measured by oil immersion and photomultiplier tube method. Two reflectance standard plates were used for calibration, and the vitrinite reflectance of the core sample was determined by comparison method.

7. A method for determining the longitudinal wave anisotropy coefficient of coal and rock through well logging, characterized in that, include: Vertical rock samples perpendicular to the bedding direction and horizontal rock samples parallel to the bedding direction were drilled from the core samples of coal and rock. The longitudinal wave velocity of the vertical rock sample and the horizontal rock sample were measured respectively, as well as the bulk density and vitrinite reflectance of the core sample. The longitudinal wave anisotropy coefficient of the core sample is determined based on the longitudinal wave velocity of the vertical and horizontal rock samples and the bulk density of the core sample. Based on the longitudinal wave anisotropy coefficient and vitrinite reflectance of multiple core samples of the coal and rock, a correlation between the longitudinal wave anisotropy coefficient and vitrinite reflectance of the core samples based on experimental analysis methods is constructed. Based on the well logging curves of the coal and rock, the continuous depth vitrinite reflectance of the coal and rock is obtained; The longitudinal wave anisotropy coefficient of the coal and rock is determined by the continuous depth vitrinite reflectance of the coal and rock, and the correlation between the longitudinal wave anisotropy coefficient of the coal and rock core sample and the vitrinite reflectance of the core sample constructed based on experimental analysis methods.

8. A logging device for determining the longitudinal wave anisotropy coefficient of coal and rock, characterized in that, include: The acquisition module is used to acquire the continuous depth vitrinite reflectance of the coal and rock based on the well logging curves of the coal and rock. The determination module is used to determine the longitudinal wave anisotropy coefficient of the coal rock at continuous depth using the vitrinite reflectance of the coal rock at continuous depth and the correlation between the longitudinal wave anisotropy coefficient of the coal rock core sample and the vitrinite reflectance of the core sample, which is pre-constructed based on experimental analysis methods.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the method for determining the anisotropy coefficient of longitudinal waves in coal and rock as described in any one of claims 1 to 3.

10. 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 program, it implements the method for determining the coal and rock longitudinal wave anisotropy coefficient as described in any one of claims 1 to 3.

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