Shale single well longitudinal wave anisotropy parameter determination method and device

Abstract

The invention relates to the technical field of geophysical exploration, in particular to a shale single well longitudinal wave anisotropy parameter determination method and device, and the method comprises the steps: obtaining longitudinal wave anisotropy parameters of core samples of different layer sections of a target well; dividing the target well stratum into an isotropic layer section and an anisotropic layer section according to the longitudinal wave anisotropy parameters of the rock core samples of different layer sections; determining a relational expression between the resistivity and the longitudinal wave velocity of the isotropic interval according to the resistivity and longitudinal wave velocity logging curve corresponding to the isotropic interval; determining the longitudinal wave velocity of the anisotropic layer section in the parallel bedding direction according to the relational expression; and determining the longitudinal wave anisotropy parameter of the target well according to the longitudinal wave velocity of the anisotropic layer section in the parallel bedding direction. The method aims to solve the problems that when longitudinal wave anisotropy parameters are determined in the prior art, the modeling process of an adopted anisotropy rock physical modeling method is tedious, key parameters are difficult to obtain, the large-scale application requirement of shale oil and gas cannot be met, and an empirical formula method is adopted.

Description

Technical Field

[0001] The present invention relates to the field of geophysical exploration technology, and in particular to a method and device for determining longitudinal wave anisotropy parameters of a shale single well. Background Art

[0002] Shale oil and gas resources have great potential and rich geological reserves, and are an important supplement to conventional oil and gas resources. Shale formations usually have obvious bedding structures, directional arrangement of clay minerals, and flat distribution of microcracks, which leads to the anisotropy of VTI media in its elastic properties, and the strength of anisotropy is related to the density of microcracks and bedding development. The greater the density of microcracks and bedding development, the stronger the anisotropy. In addition, microcracks and bedding play a pivotal role in shale oil exploration and development. Microcracks are important storage spaces and drainage systems for shale oil and gas, and bedding has a significant impact on the expansion of artificial fracture networks. Therefore, the calculation of shale anisotropy parameters and the evaluation of the development degree of microcracks and bedding in different layers are of great significance for the subsequent optimization of horizontal well target layers and the optimization design of fracturing transformation schemes.

[0003] Anisotropic parameters mainly include P-wave anisotropy parameters and S-wave anisotropy parameters. Studies have shown that there is a certain correlation between P-wave anisotropy parameters and S-wave anisotropy parameters, and S-wave anisotropy parameters can be calculated using P-wave anisotropy parameters. In addition, many actual logging data often only have P-wave velocity information and lack S-wave data. Therefore, the P-wave anisotropy parameters of a single well are mainly used to evaluate the anisotropy strength of shale formations.

[0004] The existing methods for calculating the anisotropic parameters of shale single well P-waves mainly include two categories: anisotropic rock physics modeling method and empirical formula method. Among them, the anisotropic rock physics modeling method uses a reasonable basic rock physics model to describe the characteristics of shale minerals, pores, pore structure and fluids, and obtains P-wave velocity, S-wave velocity, density and anisotropy parameters to characterize the elastic properties of rocks. This method has high calculation accuracy, but the rock physics modeling process is cumbersome, and some key parameters are difficult to obtain through conventional logging interpretation and core testing, which cannot meet the large-scale application needs of shale oil and gas; the empirical formula method is to conduct rock physics measurements, whole-rock mineral measurements and geochemical measurements of shale samples, regress and fit the relationship between P-wave anisotropy parameters and reservoir parameters such as mud content, quartz content, and organic carbon content, and combine the results of conventional logging interpretation to realize the calculation of P-wave anisotropy parameters. The defects of this method are that due to the heterogeneity of underground rocks and the expensive coring of shale samples, the efficiency of targeted experimental measurements is low, and the calculation accuracy of anisotropy parameters is controlled by the logging interpretation results of reservoir parameters, which further increases the uncertainty of anisotropy parameters of single wells. Therefore, it is crucial to establish a simple and practical method for calculating the P-wave anisotropy parameters of a single shale well based on conventional logging curves for shale oil and gas exploration and development. Summary of the invention

[0005] The present invention proposes a method and device for determining the longitudinal wave anisotropy parameters of a single shale well, so as to solve the problems that the anisotropic rock physics modeling method used in the past to determine the longitudinal wave anisotropy parameters has a cumbersome modeling process, key parameters are difficult to obtain, and cannot meet the large-scale application needs of shale oil and gas, and only the empirical formula method is used.

[0006] According to one aspect of the present invention, a method for determining a shale single well longitudinal wave anisotropy parameter is provided, comprising:

[0007] Obtain the P-wave anisotropy parameters of core samples from different layers of the target well;

[0008] According to the P-wave anisotropy parameters of the core samples of the different layers, the target well formation is divided into an isotropic layer section and an anisotropic layer section;

[0009] Determine the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section;

[0010] According to the relationship, the P-wave velocity of the anisotropic layer segment in the direction parallel to the bedding is determined;

[0011] The P-wave anisotropy parameters of the target well are determined according to the P-wave velocity in the direction parallel to the bedding of the anisotropic layer.

[0012] Preferably, before obtaining the P-wave anisotropy parameters of the core samples of different layers in the target well, the P-wave anisotropy parameters of the core samples of different layers in the target well are determined, and the method includes:

[0013] Obtain core samples from different layers of the target well;

[0014] Measuring the rock physical elastic parameters of the core sample to obtain the longitudinal wave velocity in the direction perpendicular to the bedding and the longitudinal wave velocity in the direction parallel to the bedding;

[0015] The P-wave anisotropy parameters of the core samples of different layers in the target well are determined according to the P-wave velocities in the direction perpendicular to the bedding and the P-wave velocities in the direction parallel to the bedding obtained by the measurement.

[0016] Preferably, the method for determining the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section comprises:

[0017] Performing linear, exponential, logarithmic and power statistical intersection analysis on the resistivity and P-wave velocity logging curves of the isotropic layer respectively, and obtaining the corresponding relationship between the resistivity and P-wave velocity respectively;

[0018] Among the linear, exponential, logarithmic and power-corresponding relationship equations between resistivity and P-wave velocity, the relationship equation with the largest correlation coefficient is selected as the final relationship equation between resistivity and P-wave velocity of the isotropic layer segment.

[0019] Preferably, the method for determining the P-wave anisotropy parameters of the target well according to the P-wave velocity in the bedding direction parallel to the anisotropic layer section comprises:

[0020] Determining the P-wave anisotropy parameter of the target well according to the P-wave anisotropy parameter calculation formula;

[0021] Wherein, the calculation formula of the longitudinal wave anisotropy parameter is:

[0022]

[0023] Where: ε is the longitudinal wave anisotropy parameter, V p (0°) is the P-wave velocity in the direction perpendicular to the bedding, km / s, V p (90°) is the longitudinal velocity parallel to the bedding direction, km / s.

[0024] Preferably, it also includes:

[0025] Comparing the P-wave anisotropy parameters of the target well obtained according to the P-wave velocity in the bedding direction parallel to the anisotropic layer with the P-wave anisotropy parameters of the core samples of different layers of the target well obtained, and determining the relative error between the two;

[0026] It is determined whether the relative error is within a predetermined error range. If so, the relationship between the resistivity and the P-wave velocity can be used to determine the P-wave anisotropy parameters of the target well. Otherwise, it cannot be used to determine the P-wave anisotropy parameters of the target well.

[0027] Preferably, the different layer sections include at least: the target layer and its adjacent upper and lower strata.

[0028] Preferably, the method for dividing the target well formation into isotropic layers and anisotropic layers according to the longitudinal wave anisotropy parameters of core samples in different layers comprises:

[0029] It is determined whether the longitudinal wave anisotropy parameter of the core sample is less than a predetermined value. If so, the layer segment corresponding to the longitudinal wave anisotropy parameter of the core sample is an isotropic layer segment. If not, the layer segment corresponding to the longitudinal wave anisotropy parameter of the core sample is an anisotropic layer segment.

[0030] According to one aspect of the present invention, a device for determining a shale single well longitudinal wave anisotropy parameter is provided, comprising:

[0031] An acquisition unit, used to acquire the longitudinal wave anisotropy parameters of core samples of different layers of the target well;

[0032] A division unit, used for dividing the target well formation into isotropic layer sections and anisotropic layer sections according to the longitudinal wave anisotropy parameters of the core samples of the different layer sections;

[0033] A relationship determination unit, used for determining the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section;

[0034] A P-wave velocity determination unit, used to determine the P-wave velocity of the anisotropic layer segment in a direction parallel to the bedding according to the relationship;

[0035] A compressional wave anisotropy parameter determination unit is used to determine the compressional wave anisotropy parameter of the target well according to the compressional wave velocity in the direction parallel to the bedding of the anisotropic layer segment.

[0036] The present invention has at least the following beneficial effects:

[0037] The present invention proposes a method and device for determining the P-wave anisotropy parameters of a single shale well. The isotropic layer segment and the anisotropic layer segment are divided according to the measurement results of the core sample, and the relationship between the resistivity and the P-wave velocity is determined according to the isotropic layer segment, so as to obtain the P-wave velocity of the anisotropic layer segment, and then obtain the P-wave anisotropy parameters of the single well. The method has a simple implementation process and high efficiency. The calculation results are compared with the measurement results of the core sample to verify that the method has high accuracy, and does not require complex and difficult-to-obtain logging parameters, does not require coring and measurement operations in multiple layers, saves energy and construction costs, and can meet the large-scale application needs of shale oil and gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present invention and, together with the specification, are used to explain the technical solutions of the present invention.

[0039] Figure 1 A flow chart showing a method for determining shale single well longitudinal wave anisotropy parameters according to an embodiment of the present invention;

[0040] Figure 2 A histogram of longitudinal wave anisotropy parameters of a core sample according to an embodiment of the present invention is shown;

[0041] Figure 3 The cross-plot of linear resistivity and P-wave velocity of an isotropic layer segment according to an embodiment of the present invention is shown;

[0042] Figure 4 The cross-plot of isotropic layer section exponential resistivity and P-wave velocity according to an embodiment of the present invention is shown;

[0043] Figure 5 The cross-plot of logarithmic resistivity and P-wave velocity of an isotropic layer according to an embodiment of the present invention is shown;

[0044] Figure 6 The cross-plot of power-order resistivity and P-wave velocity of an isotropic layer according to an embodiment of the present invention is shown;

[0045] Figure 7 A comparison diagram of the P-wave anisotropy parameters of Well A obtained by the method of the present invention and the P-wave anisotropy parameters obtained by core measurement according to an embodiment of the present invention is shown.

[0046] Figure 8 A relative error histogram of the P-wave anisotropy parameters obtained by the method of the present invention and the P-wave anisotropy parameters obtained by core measurement in Well A according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0047] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0048] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0049] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0050] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0051] Figure 1 A flow chart showing a method for determining shale single well longitudinal wave anisotropy parameters according to an embodiment of the present invention; Figure 2 A histogram of longitudinal wave anisotropy parameters of a core sample according to an embodiment of the present invention is shown; Figure 3 The cross-plot of linear resistivity and P-wave velocity of an isotropic layer segment according to an embodiment of the present invention is shown; Figure 4 The cross-plot of isotropic layer section exponential resistivity and P-wave velocity according to an embodiment of the present invention is shown; Figure 5 The cross-plot of logarithmic resistivity and P-wave velocity of an isotropic layer according to an embodiment of the present invention is shown; Figure 6 The cross-plot of power-order resistivity and P-wave velocity of an isotropic layer according to an embodiment of the present invention is shown; Figure 7 A comparison diagram of the P-wave anisotropy parameters of Well A obtained by the method of the present invention and the P-wave anisotropy parameters obtained by core measurement according to an embodiment of the present invention is shown. Figure 8 The relative error histogram of the P-wave anisotropy parameters obtained by the method of the present invention and the P-wave anisotropy parameters obtained by core measurement in Well A according to an embodiment of the present invention is shown. Figure 1-8 As shown, a method for determining the P-wave anisotropy parameters of a shale single well comprises: step S01: obtaining the P-wave anisotropy parameters of core samples of different layers of a target well; step S02: dividing the target well formation into an isotropic layer segment and an anisotropic layer segment according to the P-wave anisotropy parameters of the core samples of different layers; step S03: determining the relationship between the resistivity and P-wave velocity of the isotropic layer segment according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer segment; step S04: determining the P-wave velocity of the anisotropic layer segment in the direction parallel to the bedding according to the relationship; step S05: determining the P-wave anisotropy parameters of the target well according to the P-wave velocity of the anisotropic layer segment in the direction parallel to the bedding.

[0052] The method for determining the longitudinal wave anisotropy parameters of a shale single well provided by the embodiment of the present invention specifically comprises the following steps:

[0053] Step S01: Obtaining the longitudinal wave anisotropy parameters of core samples of different layers in the target well;

[0054] In the present invention, before obtaining the P-wave anisotropy parameters of core samples from different layers of the target well, the P-wave anisotropy parameters of core samples from different layers of the target well are determined. The method includes: obtaining core samples from different layers of the target well; measuring the rock physical elastic parameters of the core samples to obtain the P-wave velocity in the direction perpendicular to the bedding direction and the P-wave velocity in the direction parallel to the bedding direction; and determining the P-wave anisotropy parameters of core samples from different layers of the target well based on the P-wave velocity in the direction perpendicular to the bedding direction and the P-wave velocity in the direction parallel to the bedding direction obtained by the measurements.

[0055] In the present invention, the different layer sections at least include: the target layer and its adjacent upper and lower strata.

[0056] In the embodiment of the present invention, rock physical elastic parameters of core samples in different layers are measured to obtain the longitudinal wave velocity in the direction perpendicular to the bedding and the longitudinal velocity in the direction parallel to the bedding; the different layers should at least include the shale target layer and its adjacent upper and lower shale formations.

[0057] Taking Well A in a block in the northern Songliao Basin as an example, the shale target layer section studied is located in the Qingshankou Formation, the overlying stratum is the Yaojia Formation, and the underlying stratum is the Quantou Formation. For the Qingshankou Formation, Yaojia Formation and Quantou Formation formations, 10 core samples were selected to carry out rock physical elastic parameter measurements, including 7 cores of the Qingshankou Formation, 2 cores of the Yaojia Formation, and 1 core of the Quantou Formation. The cores of the Yaojia Formation and the Quantou Formation are all mudstones, and the core samples of the Qingshankou Formation include 4 shales, 2 dolomite interlayers, and 1 siltstone interlayer.

[0058] Substitute the P-wave velocity in the direction perpendicular to the bedding and the P-wave velocity in the direction parallel to the bedding corresponding to each core sample into the P-wave anisotropy parameter calculation formula to obtain the P-wave anisotropy parameter of each core sample obtained by measurement. The P-wave anisotropy parameter calculation formula is the same as the following method (2).

[0059] Step S02: Divide the target well formation into isotropic layers and anisotropic layers according to the P-wave anisotropy parameters of the core samples of different layers.

[0060] In the present invention, the method for dividing the target well formation into isotropic layers and anisotropic layers according to the P-wave anisotropy parameters of core samples in different layers comprises: judging whether the P-wave anisotropy parameter of the core sample is less than a predetermined value; if so, the layer segment corresponding to the P-wave anisotropy parameter of the core sample is an isotropic layer segment; if not, the layer segment corresponding to the P-wave anisotropy parameter of the core sample is an anisotropic layer segment.

[0061] In the embodiment of the present invention, the method for dividing the isotropic layer section and the anisotropic layer section is as follows: determine whether the P-wave anisotropy parameter value obtained by measuring the rock physical elastic parameters is less than a predetermined value or reaches a predetermined multiple. If so, the layer section corresponding to the P-wave anisotropy parameter is an isotropic layer section, otherwise, the layer section corresponding to the P-wave anisotropy parameter is an anisotropic layer section. Among them, the predetermined value is preferably 0.05, and the predetermined multiple is preferably 10 times; the predetermined value can also be set according to the specific formation conditions of the target well. Generally, the difference between the P-wave anisotropy parameter values ​​of the isotropic layer section and the anisotropic layer section is about 10 times.

[0062] Figure 2This is a histogram of P-wave anisotropy parameters obtained by measuring rock physical elastic parameters for 10 core samples in Well A. It can be seen that the mudstones of the Yaojia Formation and Quantou Formation have weak anisotropy, with P-wave anisotropy parameters between 0.02-0.04; the shale of the Qingshankou Formation has strong anisotropy, with P-wave anisotropy parameters between 0.59-0.69, and the P-wave anisotropy parameters of dolomite and siltstone interlayers are smaller than those of shale, ranging from 0.19-0.35. It can be seen that the Yaojia Formation and Quantou Formation have weak anisotropy, which is similar to isotropic media, so the overlying Yaojia Formation and the underlying Quantou Formation are divided into isotropic intervals; the Qingshankou Formation has strong anisotropy, so the Qingshankou Formation is divided into anisotropic intervals.

[0063] Step S03: Determine the relationship between the resistivity and P-wave velocity of the isotropic layer segment according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer segment.

[0064] In the present invention, the method for determining the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section comprises: performing linear, exponential, logarithmic and power statistical intersection analysis on the resistivity and P-wave velocity logging curves of the isotropic layer section, respectively, to obtain the corresponding relationship between the resistivity and P-wave velocity; among the relationship between the resistivity and P-wave velocity corresponding to the linear, exponential, logarithmic and power, selecting the relationship with the largest correlation coefficient as the final relationship between the resistivity and P-wave velocity of the isotropic layer section.

[0065] In an embodiment of the present invention, based on the division result of step S02, the resistivity and P-wave velocity logging curves of the isotropic layer segments in the A well logging curve are preferably subjected to statistical intersection analysis, that is, the resistivity and P-wave velocity logging curves corresponding to the Yaojia Formation and the Quantou Formation formations are subjected to linear, exponential, logarithmic, and power statistical intersection analysis, respectively, to establish the relationship between the resistivity and P-wave velocity corresponding to the isotropic layer segments, that is, the Yaojia Formation and the Quantou Formation formations.

[0066] Figure 3 This is the cross-plot of the statistical analysis of linear resistivity and P-wave velocity of the Yaojia Formation and Quantou Formation in Well A. Figure 4 This is the cross-plot of the statistical analysis of index resistivity and P-wave velocity of the Yaojia Formation and Quantou Formation in Well A. Figure 5 This is the cross-plot of the statistical analysis of logarithmic resistivity and P-wave velocity of the Yaojia Formation and Quantou Formation in Well A. Figure 6 This is the cross plot of statistical analysis of power resistivity and P-wave velocity of the Yaojia Formation and Quantou Formation in Well A.

[0067] Depend on Figure 3-6 It can be seen that in linear form, the relationship between resistivity and longitudinal wave velocity is: V P=0.0912*(LLD)+3.2294, correlation coefficient R 2 is 0.6384; in exponential form, the relationship between resistivity and longitudinal wave velocity is: V P =3.2803e 0.0229*(LLD) , correlation coefficient R 2 is 0.6083; in logarithmic form, the relationship between resistivity and longitudinal wave velocity is: V P =0.9252*ln(LLD)+2.0962, correlation coefficient R 2 is 0.7539; in terms of power form, the relationship between resistivity and longitudinal wave velocity is: V P =2.4578*(LLD) 0.2342 , correlation coefficient R 2 It is 0.7321.

[0068] By comparison, among the four statistical analysis results of linear, exponential, logarithmic, and power, the logarithmic form has the highest correlation, so the logarithmic form equation is preferred to characterize the relationship between the resistivity and P-wave velocity of the isotropic layer of Well A. The specific formula is:

[0069] V P =0.9252*ln(LLD)+2.0962 (1);

[0070] Where: V p is the P-wave velocity logging curve, km / s, LLD is the resistivity logging curve, Ω·m.

[0071] Since the Yaojia Formation and Quantou Formation have weak anisotropy and are similar to isotropic media, V p =V p (0°)=V p (90°).

[0072] Step S04: Determine the longitudinal wave velocity of the anisotropic layer segment in the direction parallel to the bedding according to the relationship.

[0073] In the embodiment of the present invention, according to the relationship between the isotropic layer resistivity and the P-wave velocity obtained in step S03, the resistivity corresponding to the anisotropic layer section of well A, i.e., the Qingshankou Formation layer section, is substituted into equation (1) to obtain the P-wave velocity V of the anisotropic layer section, i.e., the Qingshankou Formation layer section of well A parallel to the bedding direction. p .

[0074] The theoretical basis for using the relationship between the P-wave velocity and resistivity of the isotropic layer when calculating the P-wave velocity in the direction parallel to the bedding of the anisotropic layer is as follows: during deep lateral resistivity logging, the direction of the main electrode emitting current is parallel to the bedding plane of the shale formation, which mainly reflects the resistivity in the direction parallel to the bedding plane; during acoustic wave velocity logging, the acoustic wave propagates perpendicular to the bedding plane of the formation, which mainly reflects the P-wave propagation velocity in the direction perpendicular to the bedding plane.

[0075] For the Yaojia Formation and Quantou Formation, which are isotropic layers, the P-wave velocity in the direction perpendicular to the bedding and the longitudinal velocity in the direction parallel to the bedding are the same. Through statistical intersection analysis, a fitting relationship between the resistivity and P-wave velocity in the direction parallel to the bedding can be established. This relationship is applied to the anisotropic layer of the Qingshankou Formation. Combined with the resistivity logging data reflecting the parallel bedding direction, the P-wave velocity in the direction parallel to the bedding of the anisotropic layer can be obtained.

[0076] Step S05: Determine the P-wave anisotropy parameters of the target well according to the P-wave velocity of the anisotropic layer section in the bedding-parallel direction.

[0077] In the present invention, the method for determining the P-wave anisotropy parameter of the target well according to the P-wave velocity in the direction parallel to the bedding of the anisotropic layer section comprises: determining the P-wave anisotropy parameter of the target well according to the P-wave anisotropy parameter calculation formula;

[0078] Wherein, the calculation formula of the longitudinal wave anisotropy parameter is:

[0079]

[0080] Where: ε is the longitudinal wave anisotropy parameter, V p (0°) is the P-wave velocity in the direction perpendicular to the bedding, km / s, V p (90°) is the longitudinal velocity parallel to the bedding direction, km / s.

[0081] In the embodiment of the present invention, the anisotropic layer section of Well A, i.e., the longitudinal wave velocity of the Qingshankou Formation layer section perpendicular to the bedding direction, is obtained, and the longitudinal velocity V of the anisotropic layer section parallel to the bedding direction calculated in step S04 is converted to p (90°) and the P-wave velocity V in the direction perpendicular to the bedding in the anisotropic layer p (0°) is substituted into formula (2) to obtain the P-wave anisotropy parameters of the Qingshankou Formation.

[0082] The present invention also includes: comparing the P-wave anisotropy parameters of the target well obtained according to the P-wave velocity in the direction parallel to the bedding of the anisotropic layer with the P-wave anisotropy parameters of the core samples of different layers of the target well obtained, to determine the relative error between the two; judging whether the relative error is within a predetermined error range, if so, the relationship between the resistivity and P-wave velocity can be used to determine the P-wave anisotropy parameters of the target well, otherwise, it cannot be used to determine the P-wave anisotropy parameters of the target well.

[0083] In the embodiment of the present invention, the method for determining whether the relationship between the resistivity and P-wave velocity of the finally selected isotropic layer section, i.e., equation (1), can be used to determine the P-wave anisotropy parameters of the target well is as follows: determining whether the relative error between the P-wave anisotropy parameters calculated by using the relationship between the resistivity and P-wave velocity and the P-wave anisotropy parameters measured by the core sample is within a predetermined error range. If so, the relationship between the resistivity and P-wave velocity of the finally selected isotropic layer section can be used to determine the P-wave anisotropy parameters of the anisotropic layer section of the target well. Otherwise, it cannot be used to determine the P-wave anisotropy parameters of the anisotropic layer section of the target well. The predetermined error range is defined as: the average value of the relative error of each core sample is less than 10%, and the predetermined error range can also be set according to the specific formation conditions of the target well.

[0084] According to steps S01 to S05, the P-wave anisotropy parameters corresponding to different depths of Well A can be calculated, including the P-wave anisotropy parameters of the well depth corresponding to each core sample. By comparing the P-wave anisotropy parameters calculated according to the above steps with the P-wave anisotropy parameters obtained by measuring the rock physics elastic parameters of the core sample, it can be verified whether the P-wave anisotropy parameters obtained by the above method are correct, thereby proving whether the P-wave anisotropy parameter curve of the single well calculated this time can be used for subsequent analysis.

[0085] Figure 7 The figure is a comparison of the P-wave anisotropy parameters calculated by the above steps S01 to S05 for Well A and the P-wave anisotropy parameters measured by core samples. In the figure, from left to right, the first column is the depth, the second column is the acoustic time difference, the third column is the deep lateral resistivity, and the solid line in the fourth column is the P-wave anisotropy parameters calculated by the above method, and the solid box is the P-wave anisotropy parameters measured by core samples. Figure 7 It can be seen that the P-wave anisotropy parameters obtained by measuring the core samples are basically on the P-wave anisotropy parameter curve calculated according to the above steps, indicating that the P-wave anisotropy parameters calculated by the above method are more accurate.

[0086] Figure 8The following is a statistical histogram of the relative errors between the P-wave anisotropy parameters calculated by the above method and the P-wave anisotropy parameters measured by the core samples of the 7 Qingshankou Formation. Figure 8 As shown in the figure, the average relative error between the calculated P-wave anisotropy parameters and the P-wave anisotropy parameters obtained by core measurement is 7.96%, which is within the predetermined error range. In addition, the P-wave anisotropy parameters of dolomite and siltstone interlayers with high resistivity and low acoustic time difference are smaller than those of adjacent shale formations, which is consistent with the overall understanding of anisotropy. This shows that the calculation results are reliable and can provide a basis for the subsequent optimization design of horizontal well target layers and fracturing transformation plans.

[0087] It can be understood that the above-mentioned various method embodiments mentioned in the present invention can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present invention will not go into details.

[0088] The execution subject of the method for determining the anisotropic parameters of longitudinal waves of a shale single well may be a device for determining the anisotropic parameters of longitudinal waves of a shale single well. For example, the method for determining the anisotropic parameters of longitudinal waves of a shale single well may be executed by a terminal device or a server or other processing device, wherein the terminal device may be a user equipment (UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (PDA), a handheld device, a computing device, a vehicle-mounted device, a wearable device, etc. In some possible implementations, the method for determining the anisotropic parameters of longitudinal waves of a shale single well may be implemented by a processor calling computer-readable instructions stored in a memory.

[0089] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0090] The present invention also provides a device for determining the P-wave anisotropy parameters of a single shale well, which is characterized by comprising: an acquisition unit, used for acquiring the P-wave anisotropy parameters of core samples of different layers of the target well; a division unit, used for dividing the target well formation into isotropic layers and anisotropic layers according to the P-wave anisotropy parameters of the core samples of different layers; a relationship determination unit, used for determining the relationship between the resistivity and P-wave velocity of the isotropic layer according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer; a P-wave velocity determination unit, used for determining the P-wave velocity of the anisotropic layer in the direction parallel to the bedding according to the relationship; and a P-wave anisotropy parameter determination unit, used for determining the P-wave anisotropy parameters of the target well according to the P-wave velocity of the anisotropic layer in the direction parallel to the bedding.

[0091] In some embodiments, the functions or modules and units included in the device provided by the embodiment of the present invention can be used to execute the method described in the above method embodiment. Its specific implementation can refer to the description of the above method embodiment. For the sake of brevity, it will not be repeated here.

[0092] The present invention is based on the measurement of elastic parameters of core samples, relying on the characteristics of electrical logging current flowing in parallel to the formation direction and acoustic logging sound waves propagating in perpendicular to the formation direction, to establish a shale vertical well P-wave anisotropy parameter calculation method based on conventional resistivity and P-wave velocity logging curves; compared with the existing anisotropic rock physics modeling method and empirical formula method, the method of the present invention has simple steps, and the implementation process is easier and faster. Based on conventional logging curves, efficient calculation of anisotropic parameters of multiple wells can be achieved, which can meet the large-scale application needs of shale oil and gas reservoirs, and the P-wave anisotropy parameters calculated by the present invention are compared and verified with the P-wave anisotropy parameters obtained by measuring the rock physics elastic parameters of core samples. The two have good consistency, small relative error, and are in line with the overall understanding of anisotropy. The calculation result is reliable, which can provide a basis for subsequent horizontal well target layer optimization and fracturing transformation plan optimization design, and is of great significance for shale oil and gas exploration and development.

[0093] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for determining longitudinal wave anisotropy parameters of a shale single well, characterized in that: include: Obtain the P-wave anisotropy parameters of core samples from different layers of the target well; According to the P-wave anisotropy parameters of the core samples of the different layers, the target well formation is divided into an isotropic layer section and an anisotropic layer section; Determine the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section; According to the relationship, the P-wave velocity of the anisotropic layer segment in the direction parallel to the bedding is determined; The P-wave anisotropy parameters of the target well are determined according to the P-wave velocity in the direction parallel to the bedding of the anisotropic layer.

2. The method for determining the longitudinal wave anisotropy parameters of a shale single well according to claim 1, characterized in that: Before obtaining the longitudinal wave anisotropy parameters of the core samples of different layers of the target well, the longitudinal wave anisotropy parameters of the core samples of different layers of the target well are determined, and the method includes: Obtain core samples from different layers of the target well; Measuring the rock physical elastic parameters of the core sample to obtain the longitudinal wave velocity in the direction perpendicular to the bedding and the longitudinal wave velocity in the direction parallel to the bedding; The P-wave anisotropy parameters of the core samples of different layers in the target well are determined according to the P-wave velocities in the direction perpendicular to the bedding and the P-wave velocities in the direction parallel to the bedding obtained by the measurement.

3. The method for determining shale single well longitudinal wave anisotropy parameters according to claim 1, characterized in that: The method for determining the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section comprises: Performing linear, exponential, logarithmic and power statistical intersection analysis on the resistivity and P-wave velocity logging curves of the isotropic layer respectively, and obtaining the corresponding relationship between the resistivity and P-wave velocity respectively; Among the linear, exponential, logarithmic and power-corresponding relationship equations between resistivity and P-wave velocity, the relationship equation with the largest correlation coefficient is selected as the final relationship equation between resistivity and P-wave velocity of the isotropic layer segment.

4. The method for determining shale single well longitudinal wave anisotropy parameters according to claim 1, characterized in that: The method for determining the P-wave anisotropy parameters of the target well according to the P-wave velocity in the direction parallel to the bedding of the anisotropic layer section comprises: Determining the P-wave anisotropy parameter of the target well according to the P-wave anisotropy parameter calculation formula; Wherein, the calculation formula of the longitudinal wave anisotropy parameter is: Where: ε is the longitudinal wave anisotropy parameter, V p (0°) is the P-wave velocity in the direction perpendicular to the bedding, km / s, V p (90°) is the longitudinal velocity parallel to the bedding direction, km / s.

5. The method for determining shale single well longitudinal wave anisotropy parameters according to claim 1, characterized in that: Also includes: Comparing the P-wave anisotropy parameters of the target well obtained according to the P-wave velocity in the bedding direction parallel to the anisotropic layer with the P-wave anisotropy parameters of the core samples of different layers of the target well obtained, and determining the relative error between the two; It is determined whether the relative error is within a predetermined error range. If so, the relationship between the resistivity and the P-wave velocity can be used to determine the P-wave anisotropy parameters of the target well. Otherwise, it cannot be used to determine the P-wave anisotropy parameters of the target well.

6. The method for determining shale single well longitudinal wave anisotropy parameters according to claim 1, characterized in that: The different layer sections at least include: the target layer and its adjacent upper and lower strata.

7. The method for determining the longitudinal wave anisotropy parameters of a shale single well according to any one of claims 1 to 6, characterized in that: The method for dividing the target well formation into isotropic layer sections and anisotropic layer sections according to the longitudinal wave anisotropy parameters of core samples in different layer sections comprises: It is determined whether the longitudinal wave anisotropy parameter of the core sample is less than a predetermined value. If so, the layer segment corresponding to the longitudinal wave anisotropy parameter of the core sample is an isotropic layer segment. If not, the layer segment corresponding to the longitudinal wave anisotropy parameter of the core sample is an anisotropic layer segment.

8. A device for determining longitudinal wave anisotropy parameters of a shale single well, characterized in that: include: An acquisition unit, used to acquire the longitudinal wave anisotropy parameters of core samples of different layers of the target well; A division unit, used for dividing the target well formation into isotropic layer sections and anisotropic layer sections according to the longitudinal wave anisotropy parameters of the core samples of the different layer sections; A relationship determination unit, used for determining the relationship between the resistivity and P-wave velocity of the isotropic layer section according to the resistivity and P-wave velocity logging curves corresponding to the isotropic layer section; A P-wave velocity determination unit, used to determine the P-wave velocity of the anisotropic layer segment in a direction parallel to the bedding according to the relationship; The P-wave anisotropy parameter determination unit is used to determine the P-wave anisotropy parameter of the target well according to the P-wave velocity of the anisotropic layer section parallel to the bedding direction.

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