CN-122018023-A - Well periphery full-resolution electromagnetic imaging method and system

CN122018023ACN 122018023 ACN122018023 ACN 122018023ACN-122018023-A

Abstract

The invention relates to the technical field of electromagnetic detection and imaging, in particular to a well periphery full-resolution electromagnetic imaging method and system; the method comprises the steps of obtaining well stratum response through low-invasion transient electromagnetic excitation, extracting propagation state parameters, introducing spatial resolvable measurement to form well periphery spatial resolvable distribution, generating self-adaptive electromagnetic excitation configuration, achieving low resolvable area response enhancement and high resolvable area energy optimization through time-frequency azimuth phase multi-dimensional modulation, collecting multi-configuration response under the self-adaptive excitation effect, constructing time-frequency azimuth multi-dimensional fingerprints, performing sparse decoupling and normalization processing to form high-resolution multi-dimensional distinguishable fingerprint fields, constructing spatial fingerprint consistency relation by taking the fingerprint fields as cores, evolving stable interpretable full-well Zhou Dianci imaging results through consistency propagation and abnormal constraint, and synchronously calculating imaging reliability. The invention effectively improves the resolution and reliability of electromagnetic imaging under the complex well Zhou Huanjing.

Inventors

NIU DONG
SHAO LILIANG
BIAN CHENXU
HUANG HUI
LU NING
SHEN YUYING

Assignees

吉林瑞荣德能源科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260227

Claims (10)

1. The well periphery full-resolution electromagnetic imaging method is characterized by comprising the following specific implementation steps: s1, obtaining well surrounding stratum response by applying low-invasion transient electromagnetic excitation in a well, extracting propagation state parameters, calculating electromagnetic resolvable indexes, and forming well surrounding space resolvable distribution; S2, mapping to generate a space excitation demand function based on well circumference space resolvable distribution, and then adaptively adjusting time parameters, frequency parameters and phase parameters of different azimuth intervals of electromagnetic excitation signals to generate an adaptive electromagnetic excitation configuration set containing multiple excitations; S3, acquiring multi-configuration well Zhou Dianci responses under the action of a self-adaptive electromagnetic excitation configuration set, performing time-frequency analysis on the responses of all the spatial positions to construct a multi-dimensional response fingerprint vector, and performing spatial sparse decoupling and normalization on the multi-dimensional response fingerprint vector to form a decoupled normalized well Zhou Dianci response fingerprint field; S4, constructing a spatial fingerprint consistency kernel based on a well Zhou Dianci response fingerprint field, enabling structural information to be diffused in a high consistency area and suppressed in a low consistency area through an iterative propagation model, introducing local fingerprint deviation degree as an abnormal constraint factor to enhance abnormal area characteristics, and finally evolving and outputting a full well Zhou Dianci imaging result and corresponding imaging credibility distribution.
2. The well periphery full-resolution electromagnetic imaging method according to claim 1, wherein in the step S1, the propagation state parameter is extracted specifically, an equivalent propagation delay factor, an equivalent energy attenuation coefficient, a response diffusion factor and a direction consistency factor are extracted from electromagnetic response signals of all receiving directions; The equivalent propagation delay factor is used for describing the time delay of the electromagnetic disturbance propagation to the main response area; the equivalent energy attenuation coefficient is obtained by fitting the attenuation characteristic of the amplitude of the response signal along with time; the response diffusion factor is used for describing the unfolding width of the electromagnetic response in the time domain; The direction consistency factor is used to describe how similar the azimuth response modality is to an adjacent azimuth response modality.
3. The well periphery full resolution electromagnetic imaging method according to claim 2, wherein in step S2, the mapping generation spatial excitation demand function is specifically: And converting the resolvable value of each position in the well periphery spatial resolvable distribution into the excitation demand intensity required by the position through an inverse mapping relation, and weighting by combining a spatial weight function determined by well section geometry and well fluid distribution factors to form quantized spatial excitation demand distribution.
4. The well periphery full-resolution electromagnetic imaging method according to claim 3, wherein in step S2, the time parameter and the frequency parameter of the adaptively adjusting electromagnetic excitation signal are specifically: According to the space excitation demand function, the decay time constant of each excitation signal is dynamically adjusted, and the excitation angular frequency of the sub-excitation signal is synchronously adjusted, so that excitation in a low-resolution area has more sufficient time domain broadening and proper frequency domain offset.
5. The well periphery full resolution electromagnetic imaging method according to claim 4, wherein in step S2, the phase setting for the different azimuth intervals is specifically: Dividing the well periphery space into a plurality of sections along azimuth, calculating the average value of all space unit excitation demand intensities in each azimuth section as the comprehensive excitation demand weight of the section, and distributing different phase offset values on each azimuth section according to the excitation signals with different orders by the weight, so as to form a controllable phase difference of azimuth dimension.
6. The well periphery full resolution electromagnetic imaging method according to claim 5, wherein in step S3, constructing a multidimensional response fingerprint vector specifically includes: And converting the original electromagnetic response time sequence acquired by each spatial position under each excitation configuration and each azimuth by a time-frequency feature extraction operator to obtain a feature representation containing frequency spectrum, energy distribution or instantaneous frequency information, and combining the feature representations of the spatial position under all excitation configurations and all azimuth to form a multidimensional response fingerprint vector of the spatial position.
7. The well periphery full resolution electromagnetic imaging method according to claim 6, wherein in step S3, the spatial sparse decoupling of the multidimensional response fingerprint vector is specifically: Combining fingerprint vectors of the spatial units of the well Zhou Suoyou into a fingerprint matrix, and calculating the similarity of the fingerprint vector of each target spatial unit and fingerprint vectors of all other units to construct a spatial interference constraint matrix describing interference intensity; Obtaining a group of sparse projection coefficients by solving an optimization problem with regularization constraint, and linearly combining fingerprint vectors of other units by using the coefficients to approach the target unit fingerprint; subtracting the approximation result from the original fingerprint vector of the target unit to obtain a fingerprint vector with minimized interference and decoupling.
8. The well periphery full resolution electromagnetic imaging method according to claim 7, wherein in step S4, the construction of the spatial fingerprint consistency kernel is specifically: for any two spatial positions in the well periphery space, calculating the difference measurement between the corresponding decoupling normalized fingerprint vectors, inputting the difference measurement into a kernel function taking fingerprint scale parameters as control factors, wherein the output value of the kernel function is a consistency kernel value representing the similarity degree of the electromagnetic structure between the two points, and the smaller the difference is, the larger the consistency kernel value is.
9. The well periphery full resolution electromagnetic imaging method according to claim 8, wherein in step S4, the local fingerprint deviation degree is introduced as an anomaly constraint factor specifically as follows: For each spatial position, calculating the difference strength of the decoupling normalized fingerprint vector and the average value of the fingerprint vectors of all positions in the neighborhood of the spatial position to obtain the fingerprint deviation degree of the position; mapping the fingerprint deviation degree into an abnormal weight factor through a nonlinear function; in the iterative propagation process, the abnormal weight factors are used as an enhancement coefficient to act on the structural propagation field of the corresponding position, so that the fingerprint characteristics of the position are enhanced and reserved in the propagation process.
10. A well-periphery full resolution electromagnetic imaging system for performing a well-periphery full resolution electromagnetic imaging method as claimed in any one of claims 1 to 9, comprising: The well Zhou Dianci acquisition and environment sensing module is provided with an underground multidirectional adjustable excitation source and an integrated intelligent multidirectional sensor array, and is used for transmitting self-adaptive electromagnetic signals to the periphery of the well, synchronously acquiring multidirectional electromagnetic responses, carrying out local noise suppression and signal preprocessing, and outputting an initial electromagnetic response characteristic data stream with high signal-to-noise ratio; The multi-configuration excitation and space fingerprint construction module is connected to the well Zhou Dianci acquisition and environment sensing module and is used for receiving an initial electromagnetic response characteristic data stream, implementing generation and control of a multi-configuration excitation strategy, and constructing and outputting a decoupling normalized well periphery space fingerprint field by performing time-frequency analysis, characteristic extraction, space sparse decoupling and normalization on response data; The spatial fingerprint consistency evolution and anomaly enhancement module is connected with the multi-configuration excitation and spatial fingerprint construction module and is used for receiving a spatial fingerprint field, constructing a spatial consistency core based on fingerprint similarity, operating an iterative propagation algorithm to diffuse structural information in a high consistency region and enhancing local anomaly characteristics by utilizing anomaly weight factors, and finally evolving to generate a stable well periphery spatial structural field; quan Jingzhou imaging output and reliability evaluation module connected to the space fingerprint consistency evolution and anomaly enhancement module for receiving space structure field, normalizing to generate Quan Jingzhou continuous electromagnetic imaging diagram, synchronously calculating imaging reliability index of each space unit and labeling anomaly region, and outputting imaging result and reliability distribution diagram for engineering decision.

Description

Well periphery full-resolution electromagnetic imaging method and system Technical Field The invention relates to the technical field of electromagnetic detection and imaging, in particular to a well periphery full-resolution electromagnetic imaging method and system. Background In the field of oil and gas resource exploration and development, the fine mastering of the geological structure around the well is important for reservoir evaluation, well drilling safety and production increasing measure optimization, and the electromagnetic detection and imaging technology is an important geophysical means, and is sensitive to the electrical parameters of the stratum and controllable in detection range, so that the electromagnetic detection and imaging technology is continuously valued and applied to the characterization of the geological structure in the well. The invention patent with publication number CN113447990B discloses a method for observing well site electrical anomalies, which comprises the steps of transmitting near-steady electromagnetic signals to a target stratum in a well through a line source excitation signal source, collecting electromagnetic response signals through a ground receiver arranged on the ground, counting the electromagnetic response signals collected at different moments, extracting underground electrical anomalies information according to differences of different electromagnetic response signals, constructing an underground active and stratum condition electrical anomalies model based on a quasi-steady electromagnetic field characteristic response equation and a finite element numerical simulation technology, calculating to obtain ground electromagnetic theory response signals, analyzing sensitivity of different electromagnetic components to underground electrical anomalies, and optimizing an excitation mode and an arrangement mode of the ground receiver. In recent years, with the progress of sensor technology, signal processing and calculation methods, in-well electromagnetic detection is developing towards higher resolution, stronger environmental adaptability and more intelligent interpretation, and in order to better serve the fine detection requirements of complex oil and gas reservoirs and heterogeneous strata, the industry expects to develop an advanced technical method capable of fully mining electromagnetic response space information, adapting to underground complex environments and realizing high-reliability automatic imaging. Disclosure of Invention The invention aims at solving the problems in the background technology and provides a well periphery full-resolution electromagnetic imaging method and system. The technical scheme of the invention is that the well periphery full-resolution electromagnetic imaging method comprises the following specific implementation steps: s1, obtaining well surrounding stratum response by applying low-invasion transient electromagnetic excitation in a well, extracting propagation state parameters, calculating electromagnetic resolvable indexes, and forming well surrounding space resolvable distribution; S2, mapping to generate a space excitation demand function based on well circumference space resolvable distribution, and then adaptively adjusting time parameters, frequency parameters and phase parameters of different azimuth intervals of electromagnetic excitation signals to generate an adaptive electromagnetic excitation configuration set containing multiple excitations; S3, acquiring multi-configuration well Zhou Dianci responses under the action of a self-adaptive electromagnetic excitation configuration set, performing time-frequency analysis on the responses of all the spatial positions to construct a multi-dimensional response fingerprint vector, and performing spatial sparse decoupling and normalization on the multi-dimensional response fingerprint vector to form a decoupled normalized well Zhou Dianci response fingerprint field; S4, constructing a spatial fingerprint consistency kernel based on a well Zhou Dianci response fingerprint field, enabling structural information to be diffused in a high consistency area and suppressed in a low consistency area through an iterative propagation model, introducing local fingerprint deviation degree as an abnormal constraint factor to enhance abnormal area characteristics, and finally evolving and outputting a full well Zhou Dianci imaging result and corresponding imaging credibility distribution. Preferably, in the step S1, the extraction of the propagation state parameters is specifically that an equivalent propagation delay factor, an equivalent energy attenuation coefficient, a response diffusion factor and a direction consistency factor are extracted from electromagnetic response signals of all receiving directions; The equivalent propagation delay factor is used for describing the time delay of the electromagnetic disturbance propagation to the main response area; the equivalent ene