A method for pre-processing a far-detected electromagnetic wave while drilling boundary response data

Abstract

The application discloses a far-detecting while-drilling electromagnetic wave edge-probing response data preprocessing method and relates to the technical field of oil exploration and development. The method comprises the following steps: inputting original logging response data; performing instrument coefficient correction on the signal; performing equivalent source distance calibration, and calculating the correction coefficient of the absolute signal to the relative signal according to the calibration result to realize equivalent amplitude correction; calculating the equivalent mapping proportion coefficient K between the relative signal and the absolute signal to form a discrete mapping coefficient set; based on the discrete mapping coefficient set, the continuous equivalent mapping relationship is constructed by interpolation, and the absolute signal is converted into pseudo relative signal point by point by using the continuous equivalent mapping relationship; and the pseudo relative signal is input into the far-detecting while-drilling electromagnetic wave edge-probing inversion objective function to realize the inversion of the formation boundary and the resistivity parameter. The "double correction and conversion" proposed by the application realizes the unified expression of different types of logging signals in the aspects of instrument response, detection capability and response structure.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration and development technology, and in particular to a method for preprocessing electromagnetic wave edge detection response data during remote drilling. Background Technology

[0002] With the continuous development of azimuth electromagnetic logging (AWP) technology, orthogonal coil instruments and inclined coil instruments have been widely used in reservoir boundary detection and geological steering drilling. Due to the differences in their transmission and reception structures and signal representation methods, orthogonal coil instruments typically output absolute geological signals such as electromotive force, while inclined coil instruments mostly use relative geological signals such as amplitude ratio and phase difference to characterize formation boundary features. During the inversion of AWP data, different types of logging signals exhibit significant differences in dimensions, dynamic range, detection capability, and response structure. Existing methods typically employ empirical scaling, fixed scaling factors, or normalization to uniformly process different types of signals to reduce numerical differences. However, these methods primarily focus on the numerical scale of the signals and do not consider the differences in effective detection range and response structure between different signals. This makes it difficult to simultaneously ensure the consistency of the detection capability and response characteristics of different types of signals, thus affecting the stability and accuracy of subsequent detection inversion.

[0003] Therefore, there is an urgent need to study a preprocessing method for electromagnetic wave edge detection response data that can balance the consistency of detection capability and response structure. Summary of the Invention

[0004] The purpose of this invention is to propose a preprocessing method for electromagnetic wave edge detection response data during remote detection drilling. This method addresses the differences in detection capability and response structure between the absolute signal of orthogonal coil instruments and the relative signal of inclined coil instruments, thereby improving the stability and accuracy of electromagnetic wave edge detection inversion during remote detection drilling.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preprocessing electromagnetic wave edge response data during long-distance drilling includes the following steps:

[0007] s1. Set the instrument frequency, source distance, and other parameters, input the original logging response data of the orthogonal coil type remote detection instrument, and calculate the absolute geological signal and relative geological signal of the orthogonal coil type remote detection instrument at the same frequency and source distance respectively;

[0008] s2. Based on the results of complex instrument response and standard dipole response under air conditions, determine the instrument correction coefficient, perform instrument coefficient correction on the signal, and realize the equivalent conversion of complex instrument response to dipole response;

[0009] s3. Based on the consistent constraint of edge detection capability, the equivalent source distance is calibrated, and the correction coefficient from absolute signal to relative signal is calculated according to the calibration result to realize the equivalent amplitude correction;

[0010] s4. Under the condition of equivalent source distance, taking the effective response area of ​​the high-resistivity side under the preset resistivity contrast as the reference, the absolute signal is projected onto the relative signal at the corresponding position, and the equivalent mapping ratio coefficient K between the relative signal and the absolute signal is calculated to form a discrete mapping coefficient set.

[0011] s5. Based on the discrete mapping coefficient set, interpolation is used to construct a continuous equivalent mapping relationship, and the absolute signal is converted into a pseudo-relative signal point by point using the continuous equivalent mapping relationship;

[0012] s6. Using pseudo-relative signals as the input curves for remote detection while drilling electromagnetic wave edge inversion, combined with multi-initial-value gradient inversion, the formation boundary and resistivity parameters are inverted.

[0013] Optionally, step s2 specifically includes:

[0014] s2.1. Based on the air-suspended calibration results of complex instruments, simulate the theoretical response of the standard dipole under the same conditions, and determine the instrument correction coefficients corresponding to the conversion of the complex instrument response to the standard dipole response;

[0015] s2.2. The original logging response data is corrected using the instrument correction coefficients to achieve an equivalent conversion of the complex instrument response to the standard dipole response.

[0016] Optionally, in step s3, the equivalent source distance calibration and equivalent amplitude correction specifically include:

[0017] s3.1. Calculate the response curves of the absolute signal and the relative signal under the same frequency conditions;

[0018] s3.2. Establish the equivalent source distance relationship based on the effective probe edge distance corresponding to when the absolute signal and relative signal reach their respective detection thresholds. The absolute signal detection threshold is the threshold corresponding to when the absolute signal amplitude drops to the minimum response value that the instrument can recognize, and the relative signal detection threshold is the threshold corresponding to when the relative signal change drops to the minimum recognizable change.

[0019] s3.3. Determine the maximum response value of the relative geological signal based on the established equivalent source distance relationship, and calculate the correction coefficient from the absolute signal to the relative signal to achieve equivalent amplitude correction;

[0020] s3.4. Repeat steps s3.1 to s3.3 under different frequency conditions to obtain the equivalent source distance group and equivalent amplitude correction coefficient at the corresponding frequency.

[0021] Steps s2 and s3 constitute the preprocessing and correction stage of the present invention, which respectively performs correction at the instrument response level and correction at the detection capability level, i.e., the "dual correction" process.

[0022] Optionally, step s4 specifically includes:

[0023] s4.1. Under the condition of equivalent source distance, the effective response region of the high-resistivity side under resistivity contrast is used as the mapping reference region, and a point-to-point correspondence is established at the corresponding positions of the absolute signal response curve and the relative signal response curve.

[0024] s4.2. Calculate the equivalent mapping ratio K between the relative signal and the absolute signal at the corresponding position;

[0025] s4.3. Obtain the discrete mapping coefficient set Gabs / K, which consists of the absolute signal response value and the corresponding equivalent mapping scaling factor K.

[0026] Optionally, step s5 specifically includes:

[0027] s5.1. Based on the distribution range of absolute signal response values ​​in the discrete mapping coefficient set, determine the effective mapping interval corresponding to the continuous equivalent mapping relationship;

[0028] s5.2. Using the absolute signal response value as the independent variable, perform one-dimensional linear interpolation calculation on the discrete mapping coefficient set to establish a continuous equivalent mapping relationship between the absolute signal and the relative signal;

[0029] s5.3. Construct a continuous equivalent mapping function between the absolute signal and the relative signal, i.e., K=f(absolute signal value);

[0030] s5.4. Match the absolute signal response value to be converted with the continuous equivalent mapping relationship to obtain the corresponding scaling coefficient, and perform point-by-point conversion on the absolute signal to obtain a pseudo-relative signal with relative signal response characteristics.

[0031] The beneficial effects of this invention are that it proposes a "dual correction and one conversion" data preprocessing method, which establishes equivalent source distance relationships and continuous equivalent conversion relationships between different types of logging signals to achieve the conversion of absolute signals into pseudo-relative signals. Compared with the traditional fixed scaling factor method, this invention takes into account both the consistency of detection capability and response structure of different types of logging signals, and improves the stability and accuracy of remote detection while drilling electromagnetic wave edge inversion. Attached Figure Description

[0032] Figure 1 This is a flowchart of the overall process for preprocessing electromagnetic wave edge detection response data during drilling, as described in this invention.

[0033] Figure 2This is a schematic diagram illustrating the principle of instrument coefficient correction and equivalent source distance calibration according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram illustrating discrete mapping coefficient extraction according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram illustrating the construction of a continuous mapping relationship according to an embodiment of the present invention;

[0036] Figure 5 This is a comparison diagram showing the conversion effect between the method of the present invention and the fixed scaling method in one embodiment;

[0037] Figure 6 This is a comparison diagram of the inversion results of the method of the present invention and the traditional fixed-coefficient scaling method, as shown in one embodiment. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] A method for preprocessing electromagnetic wave edge response data during long-range drilling, such as... Figure 1 As shown, it includes the following steps:

[0040] s1. Set the instrument frequency, source distance, and other parameters, input the original logging response data of the orthogonal coil type remote detection instrument, and calculate the magnitude of the absolute geological signal and the relative geological signal at the same frequency and source distance of the orthogonal coil type instrument respectively.

[0041] s2. Based on the results of complex instrument responses and standard dipole responses under air conditions, determine the instrument correction coefficients, perform instrument coefficient correction on the signal, and achieve an equivalent conversion from complex instrument responses to dipole responses; specifically including:

[0042] s2.1. Based on the air-suspended calibration results of complex instruments, simulate the theoretical response of the standard dipole under the same conditions, and determine the instrument correction coefficients corresponding to the conversion of the complex instrument response to the standard dipole response;

[0043] s2.2. The original logging response data is corrected using the instrument correction coefficients to achieve an equivalent conversion of the complex instrument response to the standard dipole response.

[0044] s3. Based on the consistent constraint of edge detection capability, perform equivalent source distance calibration, and calculate the correction coefficient from absolute signal to relative signal according to the calibration results to achieve equivalent amplitude correction; the equivalent source distance calibration and equivalent amplitude correction specifically include:

[0045] s3.1. Calculate the response curves of the absolute signal and the relative signal under the same frequency conditions;

[0046] s3.2. Establish the equivalent source distance relationship based on the effective probe edge distance corresponding to when the absolute signal and relative signal reach their respective detection thresholds. The absolute signal detection threshold is the threshold corresponding to when the absolute signal amplitude drops to the minimum response value that the instrument can recognize, and the relative signal detection threshold is the threshold corresponding to when the relative signal change drops to the minimum recognizable change.

[0047] s3.3. Determine the maximum response value of the relative geological signal based on the established equivalent source distance relationship, and calculate the correction coefficient from the absolute signal to the relative signal to achieve equivalent amplitude correction;

[0048] s3.4. Repeat steps s3.1 to s3.3 under different frequency conditions to obtain the equivalent source distance group and equivalent amplitude correction coefficient at the corresponding frequency.

[0049] Steps s2 and s3 constitute the preprocessing and correction stage of the present invention, which respectively performs correction at the instrument response level and correction at the detection capability level, i.e., the "dual correction" process.

[0050] s4. Under the condition of equivalent source distance, taking the effective response region of the high-resistivity side with a resistivity contrast ratio of 100:1 as the reference, the absolute signal is projected onto the relative signal at the corresponding position, and the equivalent mapping ratio coefficient K between the relative signal and the absolute signal is calculated to form a discrete mapping coefficient set; specifically including:

[0051] s4.1. Under the condition of equivalent source distance, the effective response region of the high impedance side is used as the mapping reference region, and a point-to-point correspondence is established at the corresponding positions of the absolute signal response curve and the relative signal response curve.

[0052] s4.2. Calculate the equivalent mapping ratio K between the relative signal and the absolute signal at the corresponding position;

[0053] s4.3. Obtain the discrete mapping coefficient set Gabs / K, which consists of the absolute signal response value and the corresponding equivalent mapping scaling factor K.

[0054] The high-resistivity side refers to the side with high resistance under relative conditions, such as the side with a contrast ratio of 100:1 and a high-resistivity side of 100 Ω·m.

[0055] s5. Based on the discrete mapping coefficient set, interpolation is used to construct a continuous equivalent mapping relationship, and this continuous equivalent mapping relationship is used to convert the absolute signal point by point into a pseudo-relative signal; specifically including:

[0056] s5.1. Based on the distribution range of absolute signal response values ​​in the discrete mapping coefficient set, determine the effective mapping interval corresponding to the continuous equivalent mapping relationship;

[0057] s5.2. Using the absolute signal response value as the independent variable, perform one-dimensional linear interpolation calculation on the discrete mapping coefficient set to establish a continuous equivalent mapping relationship between the absolute signal and the relative signal;

[0058] s5.3. Construct a continuous equivalent mapping function between the absolute signal and the relative signal, i.e., K=f(absolute signal value);

[0059] s5.4. Match the absolute signal response value to be converted with the continuous equivalent mapping relationship to obtain the corresponding scaling coefficient, and perform point-by-point conversion on the absolute signal to obtain a pseudo-relative signal with relative signal response characteristics.

[0060] s6. Using pseudo-relative signals as the input curves for remote detection while drilling electromagnetic wave edge inversion, combined with traditional multi-initial-value gradient inversion, the formation boundary and resistivity parameters are inverted.

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0062] This invention provides a preprocessing method for electromagnetic wave edge detection response data during remote drilling. First, the raw logging response data from orthogonal coil and inclined coil instruments are input, and parameters such as instrument frequency and source distance are set. Then, instrument coefficient correction is performed based on air-drilling calibration results, and equivalent amplitude correction is performed based on edge detection capability consistency constraints. On this basis, a continuous equivalent conversion relationship between absolute and relative signals is established, realizing the conversion of absolute signals to pseudo-relative signals. The preprocessed pseudo-relative signals are then input into the objective function for remote electromagnetic wave edge detection inversion during remote drilling. This method is applicable to both isotropic and anisotropic media. In this embodiment, a one-dimensional two-layer isotropic model is used as the calibration model, with an upper layer resistivity of 1 Ω·m, a lower layer resistivity of 100 Ω·m, and a formation contrast ratio of 1:100. The orthogonal coil instruments operate at frequencies of 20 kHz, 50 kHz, 400 kHz, and 2 MHz, and the inclined coil instruments are calibrated using the corresponding frequencies.

[0063] Figure 2The left and right figures are schematic diagrams of instrument coefficient correction and equivalent source distance calibration, respectively. In this embodiment, a one-dimensional two-layer isotropic formation model is used as the response calculation model, where the resistivity of the low-resistivity layer is set to 1 Ω·m and the resistivity of the high-resistivity layer is set to 10000 Ω·m. The formation interface is located at a fixed distance from the instrument to simulate the boundary response characteristics under high resistivity contrast conditions. First, a standard dipole response model is established based on the 1:10000 high resistivity contrast condition, and air-drilling tests of the complex instrument are conducted to obtain the theoretical response curve of the standard dipole and the actual response curve of the complex instrument. Since the actual instrument response is affected by factors such as coil structure, circuit gain, and receiver sensitivity, there is an amplitude difference between it and the theoretical response of the standard dipole. Therefore, the instrument response correction coefficient is determined based on the amplitude relationship between the two responses. ,in For the standard dipole theory response, This describes the air-borne measured response of a complex instrument. The correction coefficients are used to correct the instrument's response, and the corrected response shows good agreement with the theoretical response of a standard dipole, achieving an equivalent conversion from the complex instrument response to the standard dipole response.

[0064] After completing the instrument coefficient calibration, the absolute signal response curves of the orthogonal coil type instrument and the relative signal response curves of the tilt coil type instrument were calculated under the same frequency conditions. For the absolute signal, the detection threshold was determined using the dynamic range method. First, the response magnitude of the absolute signal was calculated, and then the detection threshold was determined based on the maximum response amplitude and a 70dB dynamic range. The relative signal was detected using a fixed resolution threshold, with an amplitude ratio response threshold of 0.02 dB and a phase difference response threshold of 0.05°. The effective probe distances corresponding to the absolute and relative signals reaching their respective detection thresholds were calculated, and an equivalent source-distance relationship was established using the consistency of the effective probe distances as a constraint. At 20 kHz, when the source distance of the orthogonal coil instrument was 6 m, the effective probe distance corresponding to the absolute signal reaching the detection threshold was consistent with the effective probe distance of the relative signal when the source distance of the tilting coil instrument was 10.5 m. Therefore, these two sets of source distances were determined as an equivalent source distance under this frequency condition. Using the same method, multiple sets of equivalent source-distance relationships under different frequency conditions can be obtained. By changing the frequency and source distance parameters, equivalent source-distance sets for corresponding frequencies can be established, providing a basis for subsequent mapping relationship establishment.

[0065] Combination Figure 3As shown, after obtaining the equivalent source distance set, a two-layer model with a formation contrast of 1:100 is selected as the calibration benchmark model, and the effective response range of the signal is determined according to the detection thresholds of the two types of signals. Using the effective response region on the high-resistivity side as the mapping benchmark region, several sets of response values ​​at corresponding positions of absolute and relative signals are selected within the effective response range to establish a point-to-point correspondence. The equivalent mapping ratio coefficient K between the relative and absolute signals is calculated, forming a discrete mapping coefficient set composed of the absolute signal response values ​​and the corresponding ratio coefficients.

[0066] Combination Figure 4 As shown, using the absolute signal response value as the independent variable, interpolation is performed on the discrete mapping coefficient set to establish a continuous mapping relationship. During signal conversion, the absolute signal response value to be converted is matched with the continuous mapping relationship to obtain the corresponding scaling coefficient, and the point-by-point conversion from absolute signal to pseudo-relative signal is completed.

[0067] Figure 5 The left and right figures in the middle are the results of the equivalent mapping transformation of the absolute signal using the method of this invention and the result processed by the traditional absolute signal amplitude normalization method, respectively, comparing the two methods. The results show that the pseudo-relative signal obtained by the method of this invention has higher consistency with the relative signal within the effective response range, and can better maintain the response structure characteristics of the relative signal, providing more stable input data for the subsequent construction of the inversion objective function.

[0068] Combination Figure 6 As shown, to verify the effectiveness of the method of the present invention, a five-layer, four-boundary formation model was constructed for inversion testing. The model includes five formations with different resistivity and four layer interfaces, with the wellbore trajectory crossing multiple formation boundaries. Figure 6The upper figure shows the inversion result obtained after preprocessing using the traditional fixed scaling factor method, while the lower figure shows the inversion result obtained after preprocessing using the method of this invention. In the figures, the colored areas represent the resistivity distribution obtained through inversion, the black solid lines represent the wellbore trajectory, and the discrete points represent the formation boundary locations. The comparison shows that the inversion result obtained using the traditional fixed scaling factor method exhibits significant local fluctuations and boundary offsets. Using the method of this invention, the inversion result shows better consistency with the model boundary locations, improved layer interface continuity, and a more stable resistivity distribution. To further quantitatively evaluate the impact of the two preprocessing methods on the inversion results, the normalized second norm (N2) between the observed response and the inversion reconstructed response is used as the response fitting error index. A typical edge response channel is selected for calculation. The response reconstruction error obtained using the traditional fixed scaling factor method is 39.94%, while the response reconstruction error is reduced to 32.90% after using the equivalent transformation method of this invention, a reduction of approximately 17.6%. The results indicate that the continuous equivalent mapping relationship established by this invention can effectively improve the response consistency between absolute and relative signals, and enhance the stability of the inversion process. Therefore, the equivalent source distance relationship and continuous equivalent transformation relationship established by this invention can effectively realize the unified expression of absolute and relative signals, and improve the stability, boundary identification ability and inversion accuracy of remote detection while drilling electromagnetic wave edge inversion.

[0069] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preprocessing electromagnetic wave edge detection response data during long-range drilling, characterized in that, Includes the following steps: s1. Input the raw logging response data of the orthogonal coil remote detection instrument, and calculate the absolute geological signal and the relative geological signal of the orthogonal coil remote detection instrument at the same frequency source distance respectively; s2. Based on the results of complex instrument response and standard dipole response under air conditions, determine the instrument correction coefficients and perform instrument coefficient correction on the signal; s3. Based on the consistent constraint of edge detection capability, the equivalent source distance is calibrated, and the correction coefficient from absolute signal to relative signal is calculated according to the calibration result to realize the equivalent amplitude correction; s4. Under the condition of equivalent source distance, taking the effective response area of ​​the high-resistivity side under the preset resistivity contrast as the reference, the absolute signal is projected onto the relative signal at the corresponding position, and the equivalent mapping ratio coefficient K between the relative signal and the absolute signal is calculated to form a discrete mapping coefficient set. s5. Based on the discrete mapping coefficient set, interpolation is used to construct a continuous equivalent mapping relationship, and the absolute signal is converted into a pseudo-relative signal point by point using the continuous equivalent mapping relationship; s6. Using pseudo-relative signals as the input curves for remote detection while drilling electromagnetic wave edge inversion, combined with multi-initial-value gradient inversion, the formation boundary and resistivity parameters are inverted.

2. The method for preprocessing remote detection electromagnetic wave edge response data as described in claim 1, characterized in that, Step s2 specifically includes: s2.

1. Based on the air-suspended calibration results of complex instruments, simulate the theoretical response of the standard dipole under the same conditions, and determine the instrument correction coefficients corresponding to the conversion of the complex instrument response to the standard dipole response; s2.

2. The original logging response data is corrected using the instrument correction coefficients to achieve an equivalent conversion of the complex instrument response to the standard dipole response.

3. The method for preprocessing remote detection electromagnetic wave edge response data as described in claim 1, characterized in that, In step s3, the equivalent source distance calibration and equivalent amplitude correction specifically include: s3.

1. Calculate the response curves of the absolute signal and the relative signal under the same frequency conditions; s3.

2. Establish the equivalent source distance relationship based on the effective detection edge distance corresponding to when the absolute signal and relative signal reach their respective detection thresholds; s3.

3. Determine the maximum response value of the relative geological signal based on the established equivalent source distance relationship, and calculate the correction coefficient from the absolute signal to the relative signal to achieve equivalent amplitude correction; s3.

4. Repeat steps s3.1 to s3.3 under different frequency conditions to obtain the equivalent source distance group and equivalent amplitude correction coefficient at the corresponding frequency.

4. The method for preprocessing remote detection electromagnetic wave edge response data as described in claim 1, characterized in that, Step s4 specifically includes: s4.

1. Under the condition of equivalent source distance, the effective response region of the high-resistivity side under the preset resistivity contrast is used as the mapping reference region, and a point-to-point correspondence is established at the corresponding positions of the absolute signal response curve and the relative signal response curve. s4.

2. Calculate the equivalent mapping ratio K between the relative signal and the absolute signal at the corresponding position; s4.

3. Obtain the set of discrete mapping coefficients consisting of the absolute signal response value and the corresponding equivalent mapping scaling coefficient K.

5. The method for preprocessing remote detection electromagnetic wave edge response data as described in claim 1, characterized in that, Step s5 specifically includes: s5.

1. Based on the distribution range of absolute signal response values ​​in the discrete mapping coefficient set, determine the effective mapping interval corresponding to the continuous equivalent mapping relationship; s5.

2. Using the absolute signal response value as the independent variable, perform one-dimensional linear interpolation calculation on the discrete mapping coefficient set to establish a continuous equivalent mapping relationship between the absolute signal and the relative signal; s5.

3. Construct a continuous equivalent mapping function between the absolute signal and the relative signal, i.e., K=f(absolute signal value); s5.

4. Match the absolute signal response value to be converted with the continuous equivalent mapping relationship to obtain the corresponding scaling coefficient, and perform point-by-point conversion on the absolute signal to obtain a pseudo-relative signal with relative signal response characteristics.

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