A signal construction method based on a while-drilling azimuth logging instrument

Abstract

The present application relates to the technical fields of logging while drilling instrument, and especially provides a signal construction method based on a logging while drilling azimuth logging instrument.The method comprises the following steps: based on a multi-transmitting and multi-receiving antenna system of the logging while drilling azimuth logging instrument, a plurality of measurement modes under different source distances are formed, and a calculation definition formula of a voltage component compensation is constructed; through adding a symmetric compensation combination on the plurality of measurement modes under different source distances, symmetric positive compensation and symmetric inverse compensation are performed on the signal, and a joint strategy of a multi-source distance focusing and the symmetric compensation combination is constructed; and a geological signal is defined according to the joint strategy.The method reduces errors and improves measurement accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of logging-while-drilling instruments, and particularly relates to a signal construction method based on a logging-while-drilling azimuthal logging instrument. BACKGROUND

[0002] In logging-while-drilling electromagnetic wave resistivity logging, the design of a signal construction method directly affects the perception ability and anti-interference ability of a logging instrument to formation information. At present, common signal construction strategies include single-source distance measurement, multi-source distance focusing, and symmetric compensation combination. In most conventional logging-while-drilling electromagnetic wave resistivity logging instruments, due to the limitation of antenna layout structure, it is often difficult to simultaneously support multi-source distance focusing and symmetric compensation combination. For example, the antennas of some instruments are symmetrically arranged, but the source distance is short and single, the detection depth is limited, and multi-source distance focusing cannot be achieved. Some instruments have different source distance combinations, but the antenna layout structure lacks symmetry, and cannot support the symmetric compensation strategy. Therefore, the conventional logging-while-drilling electromagnetic wave resistivity logging instrument can usually only use one of the above methods, resulting in a trade-off between the detection depth and the anti-interference ability of the signal. For the problem that the multi-source distance focusing method lacks sufficient anisotropy compensation ability, the response amplitude-phase curve presents an asymmetric feature, and the measurement accuracy is poor and the error is large, SUMMARY

[0003] Therefore, the present application provides a signal construction method based on a logging-while-drilling azimuthal logging instrument to reduce errors and improve measurement accuracy.

[0004] In a first aspect, the present application provides a signal construction method based on a logging-while-drilling azimuthal logging instrument, which comprises:

[0005] Step 1, based on the multi-transmission and multi-reception antenna system of the logging-while-drilling azimuthal logging instrument, a plurality of measurement modes under different source distances are constituted, and a calculation definition formula of a compensation voltage component is constituted.

[0006] Step 2, by adding a symmetric compensation combination to the plurality of measurement modes under different source distances in step 1, symmetric positive compensation and symmetric inverse compensation are performed on the signal, and a joint strategy of multi-source distance focusing and symmetric compensation combination is constructed.

[0007] Step 3, according to the joint strategy in step 2, a geological signal is defined.

[0008] Optionally, the plurality of measurement modes under different source distances in step 1 comprise:

[0009] Introducing the coordinate system of the logging-while-drilling azimuthal logging instrument , setting 3-direction unit magnetic moment transmission-3-direction unit magnetic moment reception antenna system, the received signal voltage has 9 eigenvalues of voltage components, which are expressed by a component matrix, and the expression is:

[0010] ;

[0011] in, express When the unit magnetic moment is emitted in the direction, The eigenvalue of the voltage signal received per unit magnetic moment in the direction, The nine voltage components contain the voltage signals of all transmitting and receiving combinations in the three axial directions in three-dimensional space, thus providing omnidirectional formation information in the bottom space, serving as the basic components of the azimuth logging while drilling tool signal.

[0012] Combined with the operating frequency of the azimuth logging while drilling tool, the expression of the measurement mode under multiple groups of different source distances, namely multi-source distance focusing, is:

[0013] ;

[0014] in, and denote the real and imaginary parts of the voltage components, respectively. express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, Indicates the operating frequency of the azimuth logging while drilling tool, which are 100kHz, 400kHz, and 2MHz respectively. ; Ta represents the transmitting antenna, Rb represents the receiving antenna, , Indicates 6 types of transmission and 6 types of reception, a total of 36 antenna system modes; Represents the combination coefficient used when calculating the response of different receiving antennas, satisfying , represents the source distance between the first group of transmitting antennas Ta and receiving antennas Rb, represents the source distance between the second group of transmitting antennas Ta and receiving antennas Rb;

[0015] Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression of multi-source focusing is transformed into:

[0016] ;

[0017] ;

[0018] ;

[0019] in, 、 、 corresponding to the voltage components at 100 kHz, 400 kHz, and 2 MHz, respectively.

[0020] Optionally, the calculation formula of the compensation voltage component in step 1 comprises:

[0021] In order to resist the antenna electronic circuit noise, the electric field attenuation coefficient is used to characterize the measurement value for interference compensation; first, the voltage component is decomposed, and the expression is:

[0022] ;

[0023] wherein, and are the cos term decomposition coefficients of the real part and the imaginary part of the voltage component, respectively; and are the sin term decomposition coefficients of the real part and the imaginary part of the voltage component, respectively, and the order of the coefficient is identified by the subscript i, ;

[0024] By taking the logarithmic ratio and the angle difference, the electric field coefficient attenuation of the signal is defined, and the expression is:

[0025] ;

[0026] wherein, angle represents the angle, and satisfies the following formula:

[0027] .

[0028] Optionally, the step 2 comprises:

[0029] The signal amplitude ratio and the phase difference generated by the two symmetrical transmitting coils are averaged, and the working frequency of the while-drilling azimuthal logging instrument is combined to define the symmetrical compensation combination based on the while-drilling azimuthal logging instrument;

[0030] a. The expressions of the symmetrical positive compensation and the symmetrical inverse compensation are defined as:

[0031] ;

[0032] ;

[0033] wherein, and represent the responses of the two symmetrical antenna systems at the receiving antenna, represents the working frequency of the while-drilling azimuthal logging instrument, represents the voltage signal of the directional unit magnetic moment transmission, the voltage signal of the directional unit magnetic moment reception at the working frequency,​ ; Ta represents the transmitting antenna, Rb represents the receiving antenna;

[0034] Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression for the symmetrical positive compensation definition is transformed into:

[0035] ;

[0036] ;

[0037] ;

[0038] b. The expression of symmetric inverse compensation is transformed into:

[0039] ;

[0040] ;

[0041] ;

[0042] This results in a combined strategy of multi-source distance focusing and symmetric compensation, and the expression for signal construction is:

[0043] ;

[0044] ;

[0045] in, Indicates the selection parameters of symmetrical forward and reverse compensation, ,when When , it is symmetrical positive compensation. When , it is the symmetric inverse compensation method.

[0046] Optionally, step 3 includes:

[0047] The symmetrical positive compensation method is used to symmetrically combine the multi-source distance measurement results, so , defining the geological signal, then the amplitude ratio signal and phase difference signal The expressions are:

[0048] ;

[0049] Similarly,

[0050] ;

[0051] in, represents the imaginary unit; Indicates the operating frequency of the azimuth logging while drilling tool, express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, ; and denote the real and imaginary parts of the voltage components respectively;

[0052] .

[0053] In a second aspect, an embodiment of the present invention provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the signal construction method based on the downhole azimuth logging instrument in the first aspect or any possible implementation of the first aspect.

[0054] In a third aspect, an embodiment of the present invention provides an electronic device comprising: one or more processors; a memory; and one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs include instructions that, when executed by the device, enable the device to execute the signal construction method based on the while-drilling azimuth logging instrument in the first aspect or any possible implementation of the first aspect.

[0055] In the technical solution provided by the present invention, the method includes forming a multi-transmitter and multi-receiver antenna system based on a while-drilling azimuth logging instrument to form multiple groups of measurement modes at different source distances, and a calculation definition formula for the compensation voltage component; by adding a symmetrical compensation combination to the measurement modes at multiple groups of different source distances, symmetrical positive compensation and symmetrical inverse compensation are performed on the signal, and a joint strategy of multi-source distance focusing and symmetrical compensation combination is constructed; according to the joint strategy, the geological signal is defined, and the method reduces errors and improves measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 A flow chart of a signal construction method based on a azimuth logging while drilling tool provided in an embodiment of the present invention;

[0058] Figure 2 A schematic diagram of the antenna arrangement of a azimuth logging while drilling tool provided in an embodiment of the present invention;

[0059] Figure 3A schematic diagram of a coordinate system of a azimuth logging while drilling tool provided in an embodiment of the present invention;

[0060] Figure 4 A simulation diagram for verifying multi-source focusing provided by an embodiment of the present invention;

[0061] Figure 5 A simulation diagram of the signal amplitude ratio using the electric field attenuation coefficient provided by an embodiment of the present invention;

[0062] Figure 6 A simulation diagram of the signal phase difference using the electric field attenuation coefficient provided by an embodiment of the present invention;

[0063] Figure 7 Signal simulation diagram of symmetrical compensation provided by an embodiment of the present invention, where (a) is the signal amplitude ratio of symmetrical positive compensation; (b) is the signal phase difference of symmetrical positive compensation; (c) is the signal amplitude ratio of symmetrical inverse compensation; (d) is the signal phase difference of symmetrical inverse compensation;

[0064] Figure 8 Figures showing signal-to-noise ratio simulations for different signals provided by an embodiment of the present invention, where (a) shows the signal-to-noise ratio of the signal obtained using a combined strategy of multi-source focusing and symmetric compensation; (b) shows the signal-to-noise ratio of the signal obtained using only multi-source focusing; (c) shows the signal-to-noise ratio of the signal obtained using only symmetric compensation; and (d) shows the signal-to-noise ratio of the signal obtained using a single-source focusing measurement.

[0065] Figure 9 A signal-to-noise error comparison diagram provided by an embodiment of the present invention;

[0066] Figure 10 Schematic diagram of the comparison of the noise impact of the geological signal detection distance provided by the embodiment of the present invention, wherein (a) is the amplitude ratio detection distance; (b) is the phase difference detection distance;

[0067] Figure 11 A schematic diagram of the rotational imaging characteristics of typical sandstone-mudstone interbeds of geological signals provided by an embodiment of the present invention;

[0068] Figure 12 A schematic diagram of thick-layer rotational imaging features of geological signals provided by an embodiment of the present invention;

[0069] Figure 13 A schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0070] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0071] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0072] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the embodiments of the present invention are also intended to include plural forms, unless the context clearly indicates other meanings.

[0073] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0074] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0075] Figure 1 The flowchart of the signal construction method based on the azimuth logging while drilling tool provided in the embodiment of the present invention is as follows: Figure 1 As shown, the method includes:

[0076] Step 1: Based on the multi-transmitter and multi-receiver antenna system of the azimuth logging while drilling tool, multiple groups of measurement modes at different source distances are formed, and the calculation definition formula of the compensation voltage component is obtained.

[0077] The azimuth logging while drilling tool in this invention is a self-developed three-dimensional holographic azimuth logging while drilling electromagnetic wave resistivity tool, which integrates multi-frequency multi-source distance excitation and fully symmetrical antenna array measurement system. The instrument antenna is arranged as follows: Figure 2As shown, the instrument uses 6 transmitting and 6 receiving antenna arrays, with source distances ranging from 12 inches to 96 inches. Figure 2 T1-T6 are transmitting antennas, and R1-R6 are receiving antennas. This azimuth logging while drilling tool operates at three frequencies: 100kHz, 400kHz, and 2MHz. A 16-sector azimuth data acquisition system records rotational azimuth and received signals in real time. Combined with a downhole digital signal processor (DSP) and field-programmable gate array (FPGA) hybrid architecture, the signal is transmitted and processed as a mud pulse.

[0078] The symmetrical antenna arrangement and multi-source range excitation structure of the azimuth logging while drilling instrument in the present invention provide structural guarantees for the implementation of the joint construction method of the multi-source range focusing method and the symmetrical compensation combination method, so that it can take into account both the detection depth and anti-interference capabilities at the same time, breaking through the limitations of the traditional instrument signal construction mode in the spatial dimension.

[0079] In the embodiment of the present invention, forming multiple groups of measurement modes at different source distances in step 1 includes:

[0080] In order to describe the directional information of the received signal, the coordinate system of the azimuth logging while drilling tool is introduced in the signal processing process. ,like Figure 3 As shown in the figure, a 3-directional unit magnetic moment transmitting antenna system and a 3-directional unit magnetic moment receiving antenna system are set. The eigenvalues ​​of the received signal voltage are 9 voltage components in total, which are expressed using a component matrix. The expression is:

[0081] ;

[0082] in, express When the unit magnetic moment is emitted in the direction, The eigenvalue of the voltage signal received per unit magnetic moment in the direction, The nine voltage components contain the voltage signals of all transmitting and receiving combinations in the three axial directions in three-dimensional space, thus providing omnidirectional formation information in the bottom space, serving as the basic components of the azimuth logging while drilling tool signal.

[0083] In azimuthal logging while drilling (LWD), the detection capability of signal components is significantly affected by the antenna source spacing. Typically, short-source-spacing measurements offer higher vertical resolution but limit detection depth. Long-source-spacing measurements enhance deep response and extend detection depth, but are susceptible to noise and anisotropic interference. Therefore, leveraging the advantages of different source-spacing measurements to construct a functional signal that is both sensitive and stable at depth is crucial for improving logging signal performance.

[0084] Because a single source distance can only provide limited formation information, utilizing components or signals measured by multiple source-range antenna systems is an effective way to increase the available formation information. The multi-source-range focusing method, based on the multiple-transmitter, multi-receiver antenna system of a 3D holographic azimuthal electromagnetic wave resistivity tool, constructs measurement modes at multiple source distances. The calculation formula for the compensation component maximizes the signal's detection distance, effective dynamic range, and other measurement parameters.

[0085] Combined with the operating frequency of the azimuth logging while drilling tool, the expression of the measurement mode under multiple groups of different source distances, namely multi-source distance focusing, is:

[0086] ;

[0087] in, and denote the real and imaginary parts of the voltage components, respectively. express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, Indicates the operating frequency of the azimuth logging while drilling tool, which are 100kHz, 400kHz, and 2MHz respectively. ; Ta represents the transmitting antenna, Rb represents the receiving antenna, , Indicates 6 types of transmission and 6 types of reception, a total of 36 antenna system modes; Represents the combination coefficient used when calculating the response of different receiving antennas, satisfying , represents the source distance between the first group of transmitting antennas Ta and receiving antennas Rb, represents the source distance between the second group of transmitting antennas Ta and receiving antennas Rb;

[0088] Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression of multi-source focusing is transformed into:

[0089] ;

[0090] ;

[0091] ;

[0092] in, 、 、 These correspond to the voltage components at 100kHz, 400kHz, and 2MHz respectively.

[0093] In the embodiment of the present invention, in order to verify the superiority of the multi-source focusing method over the single-source focusing method, MATLAB is used to simulate in a standard interlayer model. The model consists of three layers of uniform strata. The upper surrounding rock stratum boundary is set to a vertical depth TVD = 10m, the lower surrounding rock stratum boundary is set to TVD = 20m, the surrounding rock layer is an isotropic layer, the target layer is an anisotropic layer, the anisotropy coefficient, the instrument operating frequency is set to 2MHz, the signals measured by the instruments T3-R5 (single source distance measurement 1) and T1-R5 (single source distance measurement 2) are used, and the signals obtained by the multi-source focusing of the two are used to simulate the instrument passing through the three layers from top to bottom. The results are as follows: Figure 4 As shown. The horizontal axis is the vertical depth TVD, and the vertical axis is the measured induced electromotive force value V. Figure 4 It can be seen that the signal after multi-source focusing responds to the position of the formation interface earlier than the single-source measurement, the amplitude of the response to the formation electrical anisotropy is higher than the single-source measurement, and the overall electromotive force peak is greater than the single-source measurement, making it easier to capture formation information.

[0094] In the embodiment of the present invention, the calculation definition of the compensation voltage component in step 1 includes:

[0095] In order to resist the noise of antenna electronic circuit, the electric field attenuation coefficient (Att / Phd) is used to characterize the measurement value for interference compensation. First, the voltage component Decompose it, the expression is:

[0096] ;

[0097] in, and are the cosine term decomposition coefficients of the real and imaginary parts of the voltage components respectively; and are the sin term decomposition coefficients of the real and imaginary parts of the voltage components, respectively. The order of the coefficient is identified by the subscript i. ;

[0098] By taking the logarithmic ratio and the angle difference, the electric field coefficient attenuation of the signal is defined as follows:

[0099] ;

[0100] Where angle represents the angle and satisfies the following formula:

[0101] .

[0102] In the embodiment of the present invention, the amplitude ratio and phase difference of the signal are expressed by the component parameter ratio under the same transmitting and receiving antennas and the same wellbore conditions, so that the signal can amplify the edge detection capability while offsetting other interferences.Figure 5 and Figure 6 As shown, the horizontal axis TVD represents the vertical depth, the vertical axis Att represents the amplitude ratio, and the vertical axis Phd represents the phase difference. The amplitude ratio and phase difference results of the measured signal after the electric field attenuation coefficient method is directly used for compensation. Figure 5 and Figure 6 It can be seen that directly using the electric field attenuation coefficient method for compensation enhances the electromagnetic field coupling effect at the signal formation boundary, causing the response amplitude-phase curve to exhibit non-monotonic oscillation characteristics, with the overall amplitude only approaching 0.04dB / 1.6°. In practical applications, it is difficult to distinguish values ​​with such small amplitudes, which reduces measurement accuracy. Therefore, it is necessary to further combine the symmetrical compensation method and use positive / negative compensation strategies to separate the resistivity and anisotropy contributions and suppress the interference of non-ideal responses.

[0103] Step 2: By adding a symmetrical compensation combination to the measurement modes at multiple groups of different source distances in step 1, symmetrical positive compensation and symmetrical inverse compensation are performed on the signal, and a joint strategy of multi-source distance focusing and symmetrical compensation combination is constructed.

[0104] To address the problems of non-monotonic oscillation characteristics of the signal and too small amplitude, the present invention adds a symmetrical compensation combination method to the measurement modes under multiple groups of different source distances. This method has the application advantages of distinguishing the sensitivity of the component to the resistivity and its anisotropy and the response at the boundary, and overcoming the asymmetry of the coil system amplitude ratio and phase difference curve.

[0105] In the embodiment of the present invention, step 2 includes:

[0106] The signal amplitude ratio and phase difference generated by the two symmetrical transmitting coils are averaged, and combined with the operating frequency of the azimuth logging while drilling tool, a symmetrical compensation combination based on the azimuth logging while drilling tool is defined;

[0107] a. The expressions for symmetric positive compensation and symmetric inverse compensation are:

[0108] ;

[0109] ;

[0110] in, and It represents the response of two symmetrical antenna systems at the receiving antenna. Indicates the operating frequency of the azimuth logging while drilling tool, express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, ; Ta represents the transmitting antenna, Rb represents the receiving antenna;

[0111] Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression for the symmetrical positive compensation definition is transformed into:

[0112] ;

[0113] ;

[0114] ;

[0115] b. The expression of symmetric inverse compensation is transformed into:

[0116] ;

[0117] ;

[0118] ;

[0119] This results in a combined strategy of multi-source distance focusing and symmetric compensation, and the expression for signal construction is:

[0120] ;

[0121] ;

[0122] in, Indicates the selection parameters of symmetrical forward and reverse compensation, ,when When , it is symmetrical positive compensation. When , it is the symmetric inverse compensation method.

[0123] In this embodiment of the present invention, the measurement signals of symmetric positive compensation and symmetric inverse compensation enhance the difference between the front and back signals and eliminate non-monotonic oscillations. Symmetric positive compensation is used to eliminate anisotropic effects and enhance boundary information, while symmetric inverse compensation enhances anisotropic information.

[0124] The simulation results are as follows Figure 7 As shown, the horizontal axis TVD represents vertical depth, the vertical axis Att represents amplitude ratio, and the vertical axis Phd represents phase difference; Figure 7 In (a) and (b), symmetric positive compensation is used. Compared with the signal without symmetric compensation, the response value is amplified by more than 100 times, showing opposite peak characteristics at the upper and lower interfaces of the target layer, enhancing the formation boundary information. The response is zero in the anisotropic target layer, eliminating the anisotropic effect. Figure 7 (c) and (d) in the figure use symmetric inverse compensation. Compared with the signal without symmetric compensation, not only the response value is amplified and monotonic, but the response amplitude of the anisotropic coefficient in the anisotropic target layer is also increased by more than 100 times, enhancing the anisotropic information.

[0125] To further verify the anti-interference performance and stability advantages of the signal construction method proposed in the present invention in a noisy environment, the present invention compares and analyzes the signal-to-noise ratio performance and error statistical characteristics of the signals obtained by various construction methods under different Gaussian random noise backgrounds. The signal type and parameter settings used in the experiment are consistent with the above content. Low noise, medium noise, and high noise interference conditions are simulated under three different Gaussian random noise environments with noise variances of 0.2, 0.5, and 0.8. In addition, to comprehensively evaluate the stability of the signal under random noise perturbations, the present invention generates 1000 random noise samples for each group of noise levels.

[0126] In the embodiment of the present invention, Figure 8 As shown in (a), (b), (c) and (d), the blue, red and black symbols represent the signal-to-noise ratio under the conditions of noise variance of 0.2, 0.5 and 0.8 respectively. The error distribution and root mean square error (RMSE) of the statistical signal are normalized and the percentage of RMSE is obtained. Figure 9 The signal-to-noise error comparison chart shows the average signal-to-noise ratio and RMSE percentage, as shown in Table 1.

[0127] Table 1 Average signal-to-noise ratio and RMSE percentage

[0128] ;

[0129] Depend on Figure 8 、 Figure 9As shown in Table 1, the signal-to-noise ratio (SNR) of the signals obtained by all construction methods decreases with noise intensity. The SNR variation ranges of the signal obtained by single-source distance measurement in low-noise, medium-noise, and high-noise conditions are 9-11dB, 7-10dB, and 3-7dB, respectively. The SNR variation ranges of the signal obtained by using only multi-source distance focusing or symmetric compensation combination are similar, with SNR variation ranges of 14-16dB, 12-15dB, and 7.5-11dB in low-noise, medium-noise, and high-noise conditions, respectively. The signal-to-noise ratio of the signal obtained by the combined strategy of multi-source distance focusing and symmetric compensation combination is significantly improved compared to the signals obtained by other methods, with SNR variation ranges of 18-19dB, 15.5-18dB, and 13.5-16dB in low-noise, medium-noise, and high-noise conditions, respectively. The experimental results show that in the layered interlayer model, the noise resistance of the signal obtained by using a single method can be improved by about 6dB compared with that obtained by single-source distance measurement. The noise resistance of the signal obtained by further combining the two methods can be further improved by about 3dB. According to the signal-noise error comparison and RMSE percentage, the RMSE of the signal obtained by using the combined construction method in a high-intensity noise environment does not exceed 5%, the RMSE of the signal obtained by using only a single construction method is about 7%, and the RMSE of the signal measured using a single source distance exceeds 8%, which proves that the combined application of the methods of the present invention can improve the signal anti-interference performance and thus improve the data stability of formation detection.

[0130] Step 3: Define geological signals based on the joint strategy in step 2.

[0131] As the key response quantity for stratum interface identification and real-time trajectory adjustment, the present invention further defines the geological signal by adopting the proposed combined strategy of multi-source distance focusing and symmetric compensation.

[0132] In this embodiment of the present invention, step 3 includes:

[0133] In order to effectively enhance the geological interface signal, suppress background interference and improve the edge detection capability, the symmetrical positive compensation method is used to symmetrically combine the multi-source distance measurement results. , defining the geological signal, then the amplitude ratio signal and phase difference signal The expressions are:

[0134] ;

[0135] Similarly,

[0136] ;

[0137] in, represents the imaginary unit; Indicates the operating frequency of the azimuth logging while drilling tool, express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, ; and denote the real and imaginary parts of the voltage component respectively;

[0138] .

[0139] To verify the edge detection capability of geological signals in noisy environments, we simulated low, medium, and high noise interference conditions under three different Gaussian random noise environments with noise variances of 0.2, 0.5, and 0.8. For each noise level, we generated 1000 random noise samples and analyzed the error distribution and RMSE of the signal edge detection distance. and The average edge detection distance and RMSE percentage are shown in Table 2. The edge detection distances in low, medium and high noise environments are shown in Table 2. Figure 10 As shown in (a) and (b).

[0140] Table 2 Average edge detection distance and RMSE percentage

[0141] ;

[0142] according to Figure 10 As shown in Table 2, in the layered interlayer model, the signal amplitude is Phase difference with the signal Because an identifiable response is generated at a minimum of approximately 8.9 m or 9.1 m in front of the interface, the maximum RMSE percentage does not exceed 6%, and the minimum detection distance is not less than 8.4 m, which is 1.6 m higher than the farthest detection distance of similar instruments under the same conditions, it demonstrates the geological signal's ability to detect the formation interface. By generating opposite relative peaks at the formation interface, it can be used to assist in indicating the instrument's orientation. It also has the ability to resist anisotropy and meets the geological signal requirements of the three-dimensional holographic while-drilling azimuth electromagnetic wave resistivity instrument.

[0143] To further verify the effectiveness of the geological signal constructed based on the combined strategy of multi-source focusing and symmetric compensation in applications, rotational imaging analysis of the geological signals under different stratum thickness settings in a typical sandstone-mudstone interbedded model was performed.

[0144] Because strata of varying thickness vary in their sensitivity to electromagnetic waves, and the multi-source focusing method and symmetrical compensation combination method offer the flexibility to combine different source distances and directional components, this paper employs two geological signal detection modes: one for a typical sandstone-mudstone interbedded model and one for a thick sandstone-mudstone interbedded model. Mode 1 utilizes a source distance range of 12 to 34 inches; Mode 2 uses a source distance range of 40 to 96 inches.

[0145] First, the azimuthal resistivity response of the LWD tool was imaged using the same typical sandstone-mudstone interbed model. The specific parameters of the typical sandstone-mudstone interbed model are shown in Table 3.

[0146] Table 3 Parameters of typical sandstone-mudstone interbed model

[0147] ;

[0148] In the embodiment of the present invention, Figure 11 As shown, from top to bottom, the first track is the formation model and wellbore trajectory, and the second track is the phase difference of mode 1 signal The response curve is the third track, which is the geological signal rotation imaging diagram of the signal combined with the rotation azimuth. Figure 11 As can be seen from the imaging, when the well trajectory passes through a formation interface, the azimuthal characteristics of the instrument are characterized by bright and dark spots. During the TVD value decline phase, when the azimuthal logging while drilling tool is located in layer 1, the imaging is featureless. When the well trajectory passes from layer 1 to anisotropic layer 2, the imaging signal peaks, and a dark spot appears approximately 1 meter in advance, indicating entry into a new formation. When drilling from layer 2 to layer 3, the imaging signal peaks, and a symmetrical bright spot appears next, indicating that the azimuthal logging while drilling tool is about to leave this layer and enter the next one. During the TVD rise phase, such as when the well trajectory passes from layer 5 back to layer 4, the signal response is symmetrical with that during drilling, and the same bright spot appears, indicating that the azimuthal logging while drilling tool is passing through the same formation but in opposite directions. In the subsequent trajectory, the imaging continues to follow the regular pattern and remains featureless at any non-interface locations.

[0149] The thick sand-mudstone interbed model was used to image the azimuthal resistivity response of the LWD tool. The specific parameters of the thick sand-mudstone interbed model are shown in Table 4.

[0150] Table 4 Parameters of thick sandstone-mudstone interbed model

[0151] ;

[0152] In the embodiment of the present invention, Figure 12 As shown, from top to bottom, the first track is the formation model and wellbore trajectory, and the second track is the signal amplitude ratio of mode 2. The response curve is as follows; the third track is the geological signal rotation imaging diagram of the signal combined with the rotation azimuth. Using the same drilling trajectory and rotation imaging method, the geological signal imaging of the while drilling azimuth logging tool is formed. Figure 12 From the imaging, it can be seen that the basic characteristics of geological signal imaging in Mode 2 are consistent with those in Mode 1. Bright and dark spots are generated according to the layer interface to indicate the instrument's orientation, and the imaging remains featureless away from the boundary. However, the bright and dark spots in Mode 2 appear in advance at a maximum of 9.6 m, indicating a longer detection distance.

[0153] The geological signal rotation imaging results constructed by the present invention based on the combined strategy of multi-source distance focusing and symmetric compensation combination have normal bright spot distribution, and the response curve is highly consistent with the formation model, which verifies the effectiveness of the combined strategy under conditions of different formation thicknesses.

[0154] This invention, based on the multi-transmitter and multi-receiver antenna system of the azimuth logging while drilling instrument, constructs multiple measurement modes at different source distances. The calculation definition of the compensation voltage component verifies the superiority of the multi-source focusing method in capturing formation information more easily than the single-source method. When using the electric field attenuation coefficient method, the results lack sufficient anisotropy compensation capability, resulting in an asymmetric response amplitude-phase curve, poor measurement accuracy, and large errors. A symmetrical compensation combination method is added to the multi-source focusing method, a measurement mode at multiple source distances. A combined strategy of multi-source focusing and symmetrical compensation is proposed, which performs symmetrical positive compensation and symmetrical inverse compensation on the signal. The symmetrical positive and symmetrical inverse compensation measurements enhance the difference between the front and back signals and eliminate non-monotonic oscillations. Symmetrical positive compensation is used to eliminate anisotropic effects and enhance boundary information; symmetric inverse compensation enhances anisotropic information. Noise addition experiments were conducted using the proposed multi-source focusing and symmetric compensation strategy, using only the multi-source focusing signal, using only the symmetric compensation combination method, and a single-source focusing method. The proposed method demonstrated superior noise immunity. Based on the proposed multi-source focusing and symmetric compensation strategy, a new geological signal was defined. Noise addition experiments were conducted to verify the noise immunity of the newly defined signal. The effectiveness of the geological signal was verified in a typical sandstone-mudstone interbedded model and a thick sandstone-mudstone interbedded model, demonstrating accurate representation of stratigraphic information.

[0155] In the technical solution provided by the present invention, the method includes forming a multi-transmitter and multi-receiver antenna system based on a while-drilling azimuth logging instrument to form multiple groups of measurement modes at different source distances, and a calculation definition formula for the compensation voltage component; by adding a symmetrical compensation combination to the measurement modes at multiple groups of different source distances, symmetrical positive compensation and symmetrical inverse compensation are performed on the signal, and a joint strategy of multi-source distance focusing and symmetrical compensation combination is constructed; according to the joint strategy, the geological signal is defined, and the method reduces errors and improves measurement accuracy.

[0156] Each step of the embodiment of the present invention may be performed by an electronic device, including but not limited to a tablet computer, a portable PC, a desktop computer, etc.

[0157] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program. When the program runs, the electronic device where the computer-readable storage medium is located is controlled to execute the above-mentioned embodiment of the signal construction method based on the while-drilling azimuth logging tool.

[0158] Figure 13 A schematic diagram of an electronic device provided by an embodiment of the present invention is shown in FIG. Figure 13 As shown, the electronic device 21 includes: a processor 211, a memory 212, and a computer program 213 stored in the memory 212 and executable on the processor 211. When the computer program 213 is executed by the processor 211, the signal construction method based on the downhole azimuth logging instrument in the embodiment is implemented. To avoid repetition, they are not described here one by one.

[0159] The electronic device 21 includes, but is not limited to, a processor 211 and a memory 212. Those skilled in the art will understand that Figure 13 It is only an example of the electronic device 21 and does not constitute a limitation of the electronic device 21. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0160] The processor 211 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0161] The memory 212 can be an internal storage unit of the electronic device 21, such as the hard drive or memory of the electronic device 21. The memory 212 can also be an external storage device of the electronic device 21, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the electronic device 21. Furthermore, the memory 212 can include both the internal storage unit of the electronic device 21 and an external storage device. The memory 212 is used to store computer programs and other programs and data required by the network device. The memory 212 can also be used to temporarily store data that has been output or is about to be output.

[0162] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0163] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A signal construction method based on a while-drilling azimuth logging tool, characterized in that: The method comprises: Step 1: Based on the multi-transmitter and multi-receiver antenna system of the azimuth logging while drilling tool, multiple measurement modes with different source distances are formed, and the calculation definition formula of the compensation voltage component is obtained; Step 2: By adding a symmetrical compensation combination to the measurement modes of multiple groups at different source distances in step 1, symmetrical positive compensation and symmetrical inverse compensation are performed on the signal, thereby constructing a joint strategy of multi-source distance focusing and symmetrical compensation combination; Step 3: Define geological signals based on the joint strategy in step 2; The calculation definition of the compensation voltage component in step 1 includes: In order to resist the noise of antenna electronic circuit, the electric field attenuation coefficient is used to characterize the measured value for interference compensation. First, the voltage component Decompose it, the expression is: ； in, and are the cosine term decomposition coefficients of the real and imaginary parts of the voltage components respectively; and are the sin term decomposition coefficients of the real and imaginary parts of the voltage components, respectively. The order of the coefficient is identified by the subscript i. ; By taking the logarithmic ratio and the angle difference, the electric field coefficient attenuation of the signal is defined, and its expression is: ； Where angle represents the angle and satisfies the following formula: ； The step 2 includes: The signal amplitude ratio and phase difference generated by the two symmetrical transmitting coils are averaged, and combined with the operating frequency of the azimuth logging while drilling tool, a symmetrical compensation combination based on the azimuth logging while drilling tool is defined; a. The expressions for symmetric positive compensation and symmetric inverse compensation are: ； ； in, and It represents the response of two symmetrical antenna systems at the receiving antenna. Indicates the operating frequency of the azimuth logging while drilling tool, express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, ; Ta represents the transmitting antenna, Rb represents the receiving antenna; Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression for the symmetrical positive compensation definition is transformed into: ； ； ； b. The expression of symmetric inverse compensation is transformed into: ； ； ； This results in a combined strategy of multi-source distance focusing and symmetric compensation, and the expression for signal construction is: ； ； in, Indicates the selection parameters of symmetrical forward and reverse compensation, ,when When , it is symmetrical positive compensation. When , it is the symmetric inverse compensation method; The step 3 comprises: The symmetrical positive compensation method is used to symmetrically combine the multi-source distance measurement results, so , defining the geological signal, then the amplitude ratio signal and phase difference signal The expressions are: ； Similarly, ； in, represents the imaginary unit; Indicates the operating frequency of the azimuth logging while drilling tool, express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, ; and denote the real and imaginary parts of the voltage components respectively; ； Among them, the coordinate system of the azimuth logging while drilling tool is introduced , set the 3-direction unit magnetic moment transmitting-3-direction unit magnetic moment receiving antenna system, the received signal voltage has a total of 9 voltage components of the eigenvalue, express When the unit magnetic moment is emitted in the direction, The eigenvalue of the voltage signal received per unit magnetic moment in the direction, ; Represents the combining coefficients used when calculating the responses of different receive antennas.

2. The method according to claim 1, characterized in that The formation of multiple groups of measurement modes at different source distances in step 1 includes: Introducing the coordinate system of the azimuth logging while drilling tool , assuming a 3-directional unit magnetic moment transmitting-3-directional unit magnetic moment receiving antenna system, the eigenvalues ​​of the received signal voltage are a total of 9 voltage components, which are expressed using a component matrix, and the expression is: ； in, express When the unit magnetic moment is emitted in the direction, The eigenvalue of the voltage signal received per unit magnetic moment in the direction, The nine voltage components contain the voltage signals of all transmitting and receiving combinations in the three axial directions in three-dimensional space, thus providing omnidirectional formation information in the bottom space, serving as the basic components of the azimuth logging while drilling tool signal. Combined with the operating frequency of the azimuth logging while drilling tool, the expression of the measurement mode under multiple groups of different source distances, namely multi-source distance focusing, is: ； in, and denote the real and imaginary parts of the voltage components, respectively. express Operating frequency Directional unit magnetic moment emission, The voltage signal received per unit magnetic moment in the direction, Indicates the operating frequency of the azimuth logging while drilling tool, which are 100kHz, 400kHz, and 2MHz respectively. ; Ta represents the transmitting antenna, Rb represents the receiving antenna, , Indicates 6 types of transmission and 6 types of reception, a total of 36 antenna system modes; Represents the combination coefficient used when calculating the response of different receiving antennas, satisfying , represents the source distance between the first group of transmitting antennas Ta and receiving antennas Rb, represents the source distance between the second group of transmitting antennas Ta and receiving antennas Rb; Since the operating frequencies of the azimuth logging while drilling tool are 100kHz, 400kHz, and 2MHz, the expression of multi-source focusing is transformed into: ； ； ； in, 、 、 These correspond to the voltage components at 100kHz, 400kHz, and 2MHz respectively.

3. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the signal construction method based on the while-drilling azimuth logging tool according to any one of claims 1 to 2.

4. An electronic device, characterized in that: include: one or more processors; Memory; and one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs include instructions, which, when executed by the device, enable the device to perform the signal construction method based on the while drilling azimuth logging tool according to any one of claims 1 to 2.

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