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Quick Search     Advanced Search OGP   2023 Vol.58 Issue.6 Published 2023-12-15 ACQUISITION TECHNIQUE PROCESSING TECHNIQUE SEISMIC SIMULATION MIGRATION AND IMAGING COMPREHENSIVE RESEARCH SEISMIC GEOLOGY NON-SEISMIC REVIEW INTELLIGENT GEOPHYSICAL TECHNIQUE PESONEGY 0 2023 Vol. 58 (6): 0-0 [Abstract] ( 122 ) [HTML 1KB] [ PDF 1138KB] ( 173 ) 1445 2023 Vol. 58 (6): 1445-1445 [Abstract] ( 64 ) [HTML 1KB] [ PDF 455KB] ( 223 ) 1471 2023 Vol. 58 (6): 1471-1471 [Abstract] ( 51 ) [HTML 1KB] [ PDF 1156KB] ( 170 ) 1534 2023 Vol. 58 (6): 1534-1534 [Abstract] ( 60 ) [HTML 1KB] [ PDF 905KB] ( 183 ) INTELLIGENT GEOPHYSICAL TECHNIQUE 1299 Loss function comparison for fault interpretation of three-dimensional seismic data based on deep neural network ZHANG Miaomiao, WU Bangyu, MA Debo, WANG Zhiguo Fault interpretation is one of the key steps for seismic data interpretation.The rapid development of deep learning，represented by neural networks，has greatly improved the efficiency and accuracy of seismic fault interpretation.The neural networks are trained by stochastic gradient descent optimization.The parameters of the network model are updated iteratively by using the loss function to measure the error of the model.The selection of the loss function is crucial for the seismic fault interpretation.In this paper，to interpret 3D seismic fault，we use the 3D U-Net model as the network structure and Adam as the optimizer to train the network with 3D synthetic samples.In terms of fault interpretation effects，we compare 10 loss functions including Balanced Cross-Entropy （BCE），Dice，Focal，Cosine，Log-Cosh Dice，Tversky，Focal-Tversky，Wasserstein，BCE-Dice，and BCE-Cosine.Normalization and data augmentation are applied to the trained data to mitigate the discrepancy between synthetic and field data.With the same network model，training parameters，and stopping criteria，we compare the convergence speed，calculation efficiency，and anti-noise performance of the 10 loss functions on 3D U-Net and analyze the fault prediction effect by using actual seismic data of the F3 field from offshore Netherlands.The experimental results show that 3D U-Net trained by Tversky and focal-Tversky loss functions can predict fault with better continuity.When crossed or parallel faults are densely distributed，and adjacent fault features can influence each other，the 3D U-Net prediction faults trained by BCE，BCE-dice，and BCE-cosine loss functions are complete，clear，and rich in detail.The research can provide a reference for selecting appropriate loss functions in different scenarios for seismic fault interpretation. 2023 Vol. 58 (6): 1299-1312 [Abstract] ( 154 ) [HTML 1KB] [ PDF 6877KB] ( 270 ) 1313 Wavelet shaping deconvolution based on deep learning Ni Wenjun, Liu Shaoyong, Wang Liping, Han Bingkai, Sheng Shen Seismic data migration imaging is one of the important methods for estimating the reflectivity of underground media.However，the imaging results are often affected by the wavelet，with limited wavenumber band distribution.Effectively extending the wavenumber band of the imaging results to improve the spatial resolution is a key objective in broadband reflectivity estimation.To achieve this，we firstly point out that the wavelet and the illumination of the geometry system are two important factors that affect the resolution of imaging results from an inversion imaging perspective.Then，based on convolutional neural networks （CNN），we use broadband wavelets to construct labels and employ conventional imaging results as input features to explore the mapping relationship using CNN.We also develop a corresponding deep learning algorithm，namely the wavelet shaping deconvolution method，and design a solution to the problem of inaccurate initial wavelet estimation in deconvolution by concatenating，iterating，and updating wavelets and reflectivity.Customized broadband wavelets can take into account both low-wavenumber and high-wavenumber information and can better restore broadband reflectivity during network training.Finally，we use a known model for network pre-training，extract effective wavelets based on the target data as the initial wavelets for deconvolution of the target data，carry out wavelet shaping deconvolution processing，and test the correctness and reliability of the method through thin-layer model testing.The filed data processing results indicate that this method has great potential for practical applications. 2023 Vol. 58 (6): 1313-1321 [Abstract] ( 88 ) [HTML 1KB] [ PDF 5681KB] ( 224 ) 1322 An unsupervised random noise suppression method in frequency domain for 3D seismic data XUE Yaru, SU Junli, FENG Luyu, ZHANG Cheng, LIANG Qi Improving the signal-to-noise ratio is a key step in seismic data processing. The current deep learning-based noise reduction methods have achieved better results. However，these methods are carried out in the temporal-spatial domain based on the local similarity of the seismic data and the processing efficiency is low. In view of the lateral continuity of geological structure，the shot gathers are very similar. Thus， an unsupervised rank-reduction denoise method in frequency domain is proposed based on the low-rank feature of the same frequency component of 3D data. The low-rank principle in frequency domain of 3D data is expounded and the singular value decomposition theory is used to guide the establishment of autoencoding network； Considering the characteristics of random noise distribution in frequency domain，K-L（Kullback-Leibler） divergence is used to constrain the loss function to improve the denoising effect. The experiments on synthetic and field data verified the advantages of the proposed method in denoising performance and computational efficiency compared with the multichannel singular spectrum analysis （MSSA） and K-SVD （K-Singular Value Decomposition） methods. 2023 Vol. 58 (6): 1322-1331 [Abstract] ( 89 ) [HTML 1KB] [ PDF 9480KB] ( 222 ) 1332 Background noise attenuation method of DAS seismic data based on multiscale enhanced cascade residual network ZHONG Tie, WANG Weiyu, WANG Wei, DONG Shiqi, LU Shaoping, DONG Xintong Seismic records collected through distributed optical fiber acoustic sensing （DAS） typically exhibit a low signal-to-noise ratio （SNR） due to the pervasive influence of complex and intense background noise. How to effectively suppress background noise，restore weak upgoing reflection information，and substantially improve the SNR of DAS records havs become a prominent challenge in seismic data processing. To address the issue of complex DAS background noise attenuation，this paper proposes a multiscale enhanced cascade residual network （MECRN），which employs a dual-path cascade residual network structure to extract shallow information from DAS records. On this basis，dilated convolutional layers and multiscale modules are introduced to extract the multiscale features existing in DAS records. Additionally，skip connections are introduced to import shallow features，which enhances the feature extraction capability of MECRN and avoids effective feature loss. Finally，the local and global features are integrated by residual learning，and the reconstructed features are refined to improve the denoising capabilities of MECRN. The processing results from both simulated and field DAS data demonstrate that MECRN can effectively suppresses complex DAS background noise and accurately restores weak reflection signals，which enhances the processing capacity of DAS data significantly. 2023 Vol. 58 (6): 1332-1342 [Abstract] ( 123 ) [HTML 1KB] [ PDF 7069KB] ( 174 ) ACQUISITION TECHNIQUE 1343 The influence of seismic data quality by seasonal permafrost CHEN Jingguo, YUAN Shenghui, TANG Chuanzhang, CUI Hongliang, LI Jingye, DENG Zhiwen Due to the protection of surface vegetation in most farmland and grassland areas， seismic exploration can only be carried out in winter after the harvest of crops. People in northern China typically irrigate their farmland around mid-October each year， resulting in high water content in the soil and low winter temperatures. As the soil freezes on the surface， a set of high-speed permafrost layers form， adding complexity to near-surface structures. Vibroseis excite signals at the surface， and seismic wave propagation in frozen soil will be affected by the resonance frequency of frozen soil medium， weakening the energy of low-frequency seismic wave signals.The Results indicate that after the permafrost layer is covered， the received low-frequency information weakers and the overall spectrum shifts towards high-frequency section. In view of the complex near-surface structure caused by seasonal frozen soil， the seismic wave propagation mechanism of frozen soil layer and the actual data analysis are carried out in this paper， which can provide a solution for improving the quality of vibroseis acquisition data in seasonal frozen soil area. 2023 Vol. 58 (6): 1343-1348 [Abstract] ( 57 ) [HTML 1KB] [ PDF 5842KB] ( 244 ) 1349 Numerical simulation of shear-wave seismic vibrator-ground coupled vibration system PENG Xun, HAO Lei The interaction between the shear-wave seismic vibrator and the ground is complicated， and involves uneven contact， soil plasticity， friction， and burial depth. However， there are rare references in the systematic research on the coupled vibration of the shear-wave vibrator-ground systems. Thus， this paper builds a three-dimensional numerical simulation model of a shear-wave seismic vibrator-ground system considering multiple nonlinear factors. The coupled vibration characteristics of the system are analyzed from aspects of the strain distribution and deformation at the contact interfaces， the vibration output force， the shear wave propagation， and the energy transfer characteristics. Meanwhile， the effects of soil types， elastic modulus， and cohesion on the response characteristics of the system are investigated. The results show that there is contact asymmetry between the vibrator plate and ground due to the load mode and the soil plastic deformation， which can bring about local decoupling of the plate. The effective output force of the vibrator is only a part of the contact force， and there are obvious harmonic distortions in the generated seismic waves. The effective energy transferred from the shear-wave vibrator to the ground is limited， with a low effective energy transfer ratio of the coupling system. The soil parameters have a significant influence on the vibrator output and energy transfer characteristics， and the vibrator operates better in clay soil. Additionally， the soil elastic modulus is the main controlling factor for the vibrator plate decoupling， while increasing the soil cohesion can improve the energy transfer characteristics of the system. Therefore， numerical simulation can analyze the coupled vibration characteristics of the shear-wave vibrator-ground system， providing theoretical references for the structural design and optimization of the vibrators. 2023 Vol. 58 (6): 1349-1358 [Abstract] ( 46 ) [HTML 1KB] [ PDF 6835KB] ( 164 ) SEISMIC SIMULATION 1359 Construction of 3D geophysical model for overthrust nappe structure in the northern section of Longmen Mountain WANG Qingeng, HU Shanzheng, HUANG Youhui, DU Junguo, HE Wei, ZHOU Ming The northern section of Longmen Mountain in the Sichuan Basin is a typical overthrust nappe structure with significant potential for oil and gas exploration.In order to obtain high-quality raw seismic data，it is necessary to optimize the seismic acquisition and observation system based on the results of forward modeling of the 3D model，which depends on the construction of a 3D geophysical model.To this end，based on the interpretation results of 2D and 3D seismic data，as well as near-surface survey data，different methods are used to construct geological models according to different geological and seismic reflection characteristics in different regions.Micrologging survey results and VSP data are used to assign velocity values to the model； the accuracy of the constructed 3D geophysical model is verified by using elastic wave equation simulation.The 3D geophysical model built using this method intuitively and accurately reflects the changes in nearsurface structure and underground velocity field.The simulated single-shot records are highly consistent with the actual single-shot records，providing a model basis for the argument of geometry system parameters. 2023 Vol. 58 (6): 1359-1364 [Abstract] ( 94 ) [HTML 1KB] [ PDF 8276KB] ( 248 ) PROCESSING TECHNIQUE 1365 Method of cable floating correction based on combination of gather coherence and ghost reflection traveltime YAN Zhonghui, WANG Xiaojie, XU Huaning, CHEN Shanshan, YANG Jiajia, YANG Chuansheng In the high-resolution and small trace distance marine acquisition，due to the inherent problems of equipment，the cable unequal floating effect will be caused，there are some problems，for instance，phase axistremor and uneven NMO correction will be shown on the gather，which cannot achieve the effect of in-phase superposition，and reduce the imaging accuracy of seismic data.The conventional residual moveout correction method is difficult to accurately identify whether residual moveout is caused by the unequal floating of the cable，which will cause errors in the correction results. This paper presents a cable floating correction method based on combination of gather coherence and ghost reflection traveltime. Firstly，the sinking depth of the actual cable is calculated by using the interactive pick-up ghost reflection travel time，and then the initial moveout correction is obtained.Then the reference moveout correction is obtained by the gather coherence and the model reference trace.Finally，the moveout correction is weighted selected by the cross-correlation analysis between the two，and the moveout is applied after smoothing，the phase axis of the data achieves the effect of phase stacking，in order to improve the resolution and imaging accuracy of seismic data. In this paper，combined with the test analysis of model data and actual processing，compared with the conventional cross-correlation cable float correction method，the results show that the correction method in this paper is more accurate and effective in float correction. 2023 Vol. 58 (6): 1365-1373 [Abstract] ( 45 ) [HTML 1KB] [ PDF 5014KB] ( 177 ) 1374 S1P/S2P wave separation and shear wave splitting correction for SVP data YUE Yuanyuan, QIAN Zhongping, NIE Hongmei, SUN Pengyuan, DENG Zhiwen, LI Jianfeng For shear（S）-wave source seismic exploration， extracting fracture information from the data and performing fast/slow S-wave separation and S-wave splitting correction are of great significance for S-wave seismic data imaging with azimuthal anisotropy. The difference between SP converted wave （P-wave converted from S-wave） in S-wave source exploration data and PS converted wave （S-wave converted from P-wave） is that the S-wave splitting occurs in the process of downgoing wave or upgoing wave propagation. Therefore， the S-wave splitting characteristics of the SP wave are similar to those of the PS wave. In this paper， the tangent energy minimization method of PS wave is applied to the S-wave splitting analysis of SP wave to find the direction of underground cracks. In the application of 3D nine-component （3D9C） actual data， a technical process is formed based on the preprocessing of SP wave seismic data including common conversion point （CCP） gather extraction and NMO correction， and the corresponding crack direction of CCP is obtained by azimuthal superposition. In addition， the fast and slow converted （S1P and S2P） wave separation is carried out. At the same time， a strategy is proposed to obtain the time difference by picking up the horizon on the fast and slow wave superimposed profile. After the time difference is applied to the S-wave splitting correction， SVP without the S-wave splitting effect is obtained， and the image quality of the profile is improved. The application results of synthetic data and actual data show that the imaging profiles of S1P and S2P waves are significantly improved compared with those before separation， and the SVP reflection energy is improved after S-wave splitting correction， which verifies the feasibility of the proposed method for fast and slow wave separation and S-wave splitting correction in actual SP wave seismic data. 2023 Vol. 58 (6): 1374-1381 [Abstract] ( 52 ) [HTML 1KB] [ PDF 7462KB] ( 180 ) MIGRATION AND IMAGING 1382 Viscoacoustic FWI with a stable Q-compensated gradient JIANG Shuqi, ZHOU Hui, CHEN Hanming, ZHANG Mingkun, FU Yuxin, LI Honghui The full-waveform inversion （FWI） based on attenuation medium usually adopts the viscoacoustic wave equation，and calculates the gradient of an objective function with respect to the velocity of the media by the adjoint state method. Since both the source wavefield and adjoint wavefield are attenuated，the gradient weakens with depth resulting in reducing the modification of subsurface parameters，which slows down the convergence of the inversion. To speed up the inversion efficiency，this paper develops a viscoacoustic FWI based on the decoupled fractional Laplacian （DFL） wave equation，and provides a new gradient compensation strategy based on a stabilization factor. The new compensation strategy achieves stable compensation by setting one stabilized factor in compensation，balances the amplitudes in the recovered gradient，meanwhile maintains correct kinematics. Compared with the conventional viscoacoustic FWI，the viscoacoustic FWI with this gradient compensation strategy has faster convergence speed and higher inversion accuracy. 2023 Vol. 58 (6): 1382-1391 [Abstract] ( 128 ) [HTML 1KB] [ PDF 7437KB] ( 226 ) 1392 Application of constrained tomographic inversion in seismic velocity modeling of glutenite bodies JIN Changkun, QIN Ning, GUAN Jian, ZONG Zhaoyun, LI Kun, LIU Qunqiang Glutenite bodies widely exist in steep slope zones of faulting depression basins，and they can develop various hydrocarbon reservoir types with great exploration potential.However，due to their complex spatial distribution and overlap relationship，and large velocity differences with the surrounding rocks，it is difficult to employ the conventional grid tomographic modeling methods in the imaging domain to obtain their refined models.Thus，based on the grid tomographic inversion method in the imaging domain，this paper proposes a constrained tomographic inversion method in the imaging domain to improve the modeling accuracy of glutenite bodies.The thought of layer constraints is adopted，and the spatial distribution information of glutenite bodies obtained from seismic interpretation is combined to delineate key inversion regions.Meanwhile，it introduces the logarithmic barrier function and limits the velocity variation range of the glutenite bodies by applying inequality constraints to improve the modeling accuracy of the bodies.The application results in the BS work area indicate that compared with the original grid tomographic model，the velocity model built by this method is more consistent with the glutenite body distribution in the imaging section.Compared with the results of the fusion model，it can reveal the velocity changes inside the glutenite body，and the quality of its corresponding imaging section is also improved. 2023 Vol. 58 (6): 1392-1397 [Abstract] ( 124 ) [HTML 1KB] [ PDF 4813KB] ( 234 ) COMPREHENSIVE RESEARCH 1398 Prestack seismic inversion with reweighted L1-norm sparse constraints ZHAO Yun, WEN Xiaotao, YIN Chuan, HAN Wenming, LI Chenlong Low sparsity pseudo-layers and low resolution of traditional sparse-constrained inversion lead to difficulty in thin-layer identification.To this end，we propose a prestack seismic inversion method based on reweighted L1-norm sparse constraints，namely to combine the reflection coefficients of the formation with the elements of the reweighted matrix，and the reflection coefficients are further reweighted to optimize and construct the inversion objective function.In addition，the alternating direction method of multipliers （ADMM） is used to transform the nonlinear inversion objective function containing multiple parameters into multiple easily solvable single-parameter linear subproblems，and iterative shrinkage thresholding algorithm （ISTA） is introduced to solve the mixed norm optimal solution of the subproblems.Unlike the traditional L1-norm sparse constraints，which only consider the position information of the reflection boundary，the reweighted L1-norm exploits the amplitude information of the reflection boundary，which can more fully utilize the sparsity of the L1-norm to obtain more accurate formation velocity boundary and density boundary through the prestack seismic inversion and weaken the velocity pseudo-layer phenomenon existing in the traditional L1-norm inversion results.The model test and the application of the measured data in the field data demonstrate that the profile boundaries of P- and S-wave velocities and density obtained by the proposed method are more accurate，with higher resolution，better identification ability for thin layers，and the pseudo-layer phenomenon is greatly reduced.It can provide a more accurate data basis for the subsequent prediction of other geophysical parameters. 2023 Vol. 58 (6): 1398-1409 [Abstract] ( 60 ) [HTML 1KB] [ PDF 8214KB] ( 204 ) 1410 Sweet spot prediction in thick gas reservoirs with low permeability in Huagang Formation of Z gasfield in Xihu Sag， East China Sea Shelf Basin HE Xianke, LOU Min, TU Qicui, LI Bingying, CAI Hua The Xihu Sag of the East China Sea Shelf Basin is an area with great potential for exploring thick gas reservoirs with low permeability.The prediction of sweet spots is the key to the development of the reservoir.However，it is difficult to predict sweet spots of thick reservoirs with strong heterogeneity.The geophysical prediction technology and methods of different types of sweet spots are established for offshore thick gas reservoirs with low permeability.Firstly，based on the classification of sweet spots，rock physics and seismic forward modeling analyses are carried out to clarify the sensitive rock physics parameters and seismic response characteristics of sweet spots.Then，the appropriate pre-stack elastic inversion methods are selected to predict the spatial distribution of different types of sweet spots.The research results show that sweet spots of class I can be well characterized by direct inversion of P-wave modulus，and sweet spots of class Ⅱ can be well characterized by pseudo P-and S-wave velocity ratio inversion.The predicted thickness of the sweet spot before drilling is highly consistent with the actual drilling thickness of the development well.In addition，the coincidence rate of the sweet spot of class I is more than 80%，and that of class Ⅱis more than 70%.In conclusion，the method for sweet spot prediction is effective and highly accurate，and it has certain reference significance in the development of similar gas fields. 2023 Vol. 58 (6): 1410-1422 [Abstract] ( 57 ) [HTML 1KB] [ PDF 11561KB] ( 165 ) 1423 Amplitude ratio average method in frequency domain for Q estimation of extrinsic attenuation based on Taylor series expansion with different orders ZHANG Jin, WANG Yanguo, LAN Huitian, ZHANG Guoshu, PAN Yeli In the actual quality factor Q estimation， it is prone to have a large estimation error due to factors such as frequency band selection， wavelet superposition， noise interference， and extrinsic attenuation. Thus， the amplitude ratio average method in the frequency domain （FARA） for Q estimation based on Taylor series expansion with different orders considering extrinsic attenuation is presented. Firstly， the continuous multiplication of the amplitude ratio in the reference frequency band is utilized to eliminate the effect of extrinsic attenuation. Then， based on the 1st-4th order Taylor series expansion expression of the amplitude factor at the reference frequency point， the single-frequency point Q estimation formula for the seismic records with extrinsic attenuation is derived. Secondly， the combination of high and low reference frequency bands is adopted to weaken the impact of reference frequency bands. Finally， the average processing of all frequency points average in dominant frequency bands is leveraged to improve the algorithm’s stability. The model test shows that the combination of high and low reference frequency bands can significantly improve the Q estimation accuracy of this method， and the proposed method is less sensitive to the time difference， time window， and noise interference than the logarithmic spectral area double difference （LSADD） method. The example application shows that the Q value estimated by the FARA method with different orders has good consistency， with greater overall Q value than that of the LSADD method. This is consistent with the model test results， indicating that the Q value estimated by the FARA method is more reliable. 2023 Vol. 58 (6): 1423-1435 [Abstract] ( 95 ) [HTML 1KB] [ PDF 4719KB] ( 134 ) 1436 Seismic and well logs integration for reservoir parameter prediction and uncertainty evaluation based on relevance vector machine optimized by particle swarm optimization DAI Shiming, LI Min, TANG Jinliang, ZHU Tong, LI Jingnan, HU Huafeng There are three types of methods for predicting porosity and saturation， which are rock physics， geostatistics， and seismic multi-attribute. The first type with clear physical meaning is widely used， but it has certain limitations. The second type can improve resolution compared with conventional methods， yet it is difficult to predict reservoir parameters in complex structural areas. The support vector machine （SVM） belongs to the third type. Its computational complexity increases with the rise of sample quantity. Meanwhile， it is difficult to evaluate the uncertainty. The relevance vector machine （RVM） in the third type lacks a clear theory for selecting kernel parameters. To improve this， particle swarm optimization （PSO） is applied to guide the selection of kernel parameters. The reservoir parameters are quantitatively predicted on the basis of obtaining the optimal kernel parameters. Then， the coefficient of variation is introduced to eliminate the influence of dimension and quantify the uncertainty of prediction results. With the help of a stepwise regression algorithm to screen seismic attributes， this paper proposes a quantitative porosity and saturation prediction method based on RVM optimized by PSO （PSO-RVM）. The results of numerical simulation and field application show that： ①PSO-RVM has good learning performance， satisfying genera-lization ability， and a certain ability of anti-noise. The RMS error of PSO-RVM prediction results is lower than that of RVM， and the prediction accuracy is higher， which indicates that PSO can effectively guide the selection of RVM kernel parameters and improve the algorithm performance. ②PSO-RVM provides a posterior probability， and it can quantify uncertainty by introducing a coefficient of variation. ③From seismic and well logs data， the porosity and gas saturation are quantitatively predicted by PSO-RVM with high prediction accuracy. Additionally， the accuracy of porosity prediction is higher， and the uncertainty is lower. 2023 Vol. 58 (6): 1436-1445 [Abstract] ( 45 ) [HTML 1KB] [ PDF 4136KB] ( 161 ) 1446 Adaptive directional enhancement detection and application of seismic discontinuity information LI Kangyi, CHEN Xuehua, WU Haojie, LYU Bingnan, ZHAO Chenfei In actual seismic data， discontinuous information such as cracks and river channels often varies in diffe-rent directions and is also affected by various noises， which brings difficulties and challenges to the extraction of high-precision geological anomaly information. Therefore， based on previous methods， an adaptive direction enhancement method for seismic discontinuity information is proposed， and a Gaussian filter direction is selected according to the crack direction to perform secondary iterative filtering on seismic data. The specific steps are as follows. ①The input seismic data through a Gaussian window in all given directions within the range of 0°~180° is scanned， and the processing results in the direction of the maximum value of sum of amplitudes at each position are selected. ②A time window is chosen to scan and process data， and mapped to L-level grayscale to form seismic texture primitives. ③Texture parameters of the co-occurrence matrix for any specific direction of data within the time window are obtained， and the specific direction of processing data is determined. ④The determined crack direction is substituted into the anisotropic Gaussian filtering direction matrix for secondary iteration. ⑤The enhanced final image is obtained by employing the attribute analysis method of anisotropic volume curvature for processing data. The results show that the proposed method suppresses interference information in different directions from fractures， greatly highlights geological structural features， and better reflects the structural details and discontinuities in specific directions. Meanwhile， this method can select one or more specific directions on its own， displaying only the structural information of the selected direction. Finally， technical support is provided for structural interpretation， understan- ding of fault distribution patterns， and reservoir prediction. 2023 Vol. 58 (6): 1446-1453 [Abstract] ( 44 ) [HTML 1KB] [ PDF 7935KB] ( 159 ) 1454 Application of multi-component seismic technology in fine description of tight gas reservoirs ZHANG Ming, ZHANG Xin, LIANG Jing, JIANG Xiaoyu, GAN Lideng, YU Xiaowei The channel sandstone of Shaximiao Formation in Qiulin area of the central Sichuan Basin has the geological characteristics of multiple stages and superimposed sand bodies. The fine description of sand bodies and their superimposed relationships plays a crucial role in the deployment of horizontal wells. Since the conventional seismic exploration method is difficult to obtain the ideal effect，the multi-component seismic exploration has been carried out in the study area. The results show that：① The P wave velocity of sandstone and mudstone in Shaximiao Formation is basically the same，while the S wave velocity is highly different，so the converted wave has a great advantage in distinguishing lithology. ② The P wave data are not sensitive to the change of sand bodies，and the seismic waveform cannot reflect the superimposed relationship of sand bodies. Although the main frequency of the converted wave is lower than that of the P wave，it is sensitive to the change of lithology，and the seismic waveform has a good correspondence with the change of sand bodies. ③ The S wave velocity accuracy by the P wave pre-stack inversion is low，while the S wave velocity by joint PP-PS wave inversion has high prediction accuracy，which can accurately characterize the sand body and its superimposed relationship. The study shows that multi-component seismic technology has the potential to accurately describe sandstone reservoirs，which provides a data basis for accurate and efficient development of tight sandstone gas reservoirs in Shaximiao Formation. 2023 Vol. 58 (6): 1454-1462 [Abstract] ( 56 ) [HTML 1KB] [ PDF 15196KB] ( 191 ) 1463 Pre-stack and post-stack seismic comprehensive prediction method and its application in carbonate fractured-vuggy reservoirs LIU Tao, WANG Tieyi, SUN Ke, HAN Dong The deep carbonate fractured-vuggy reservoir in Tarim Basin is characterized by rapid lateral changes，strong heterogeneity，and complex contact relationship between fractures and caves，which seriously restrict the subsequent exploration and development.Thus，this paper studies a comprehensive prediction method of fractured-vuggy reservoirs based on pre-stack and post-stack seismic multi-attribute analysis.Based on the post-stack seismic data，we firstly select the multispectral geosteering coherence attributes as the sensitive attributes for large fault and cave prediction through multi-attribute comparative analysis.Secondly，based on pre-stack wide-azimuth seismic data，we propose an anisotropic strength characterization method based on the wide-azimuth geosteering phase attributes.The singular value decomposition （SVD） is used to calculate the ratio of the maximum singular value to the sum of singular values from different azimuth geosteering phase attributes.The obtained results can be used to characterize the distributions of anisotropic strength in the target reservoir and taken as underground fracture prediction results.Finally，the post-stack large fault and cave characterization results are combined with the pre-stack fracture prediction results for analysis，and the results can be applied to the prediction of carbonate fractured-vuggy reservoirs in Tarim Basin.The contact relationship between fractures and caves can be clearly characterized，which is more consistent with the real drilling results，thus providing a favorable basis for subsequent exploration and development. 2023 Vol. 58 (6): 1463-1471 [Abstract] ( 141 ) [HTML 1KB] [ PDF 10734KB] ( 262 ) SEISMIC GEOLOGY 1472 A study on differences of shale gas enrichment and preservation conditions：Taking the Jiaoshiba-Wulong area as an example DING Jiatong, CHEN Kongquan, TANG Jiguang, TUO Xiusong, ZHANG Douzhong Jiaoshiba-Wulong area is located in the eastern margin of Sichuan Basin， which has a good geological basis for shale gas reservoir. However， there is a significant difference in shale gas productivity between the inner and outer margin of the eastern Sichuan basin during field operation. Based on the tectonic differences， the Qiyueshan fault is taken as the boundary， and the study area is divided into Jiaoshiba tectonic belt and Wulong tectonic belt. For the study of tectonic deformation in the area differences with shale gas preservation conditions， geological data of tectonic area， in fine interpretation of seismic data， drilling data， the result shows that the coke structure of rockfill dam with rich gas are mainly distributed in the structure of positive structure—a box-like anticline and weak type circular anticline， wulong structural belt in development have negative structure—residual syncline. In this paper， a differential enrichment model is established to compare the differences in the preservation conditions of shale gas under different tectonic forms. The main controlling factor of shale gas preservation in box anticlines is fault， the fault of weakly modified arc anticlines is related to derived tensile structures， and the main controlling factor of residual synclines is the normal stress of foliation plane. 2023 Vol. 58 (6): 1472-1480 [Abstract] ( 42 ) [HTML 1KB] [ PDF 3942KB] ( 135 ) NON-SEISMIC 1481 Non-seismic target-oriented interpretation techniques and application in the western edge of Ordos Basin LI Mingrui, WANG Xuegang, YU Bo, YAO Zhichun, ZHANG Yadong, HUANG Xianghu The geology on the western edge of the Ordos Basin is complex，and the interpretation of complex underground structures and the prediction results of deep stratigraphic distribution based on existing seismic data are inconsistent with the actual drilling results.To this end，the technical idea of non-seismic interpretation is proposed.In other words，based on conventional non-seismic processing，the specific processing and interpretation focusing on geologic requirements will be reinforced.In view of the strike-slip fault development feature，the enhancement of gravity and magnetic anomaly and body display techniques are used to highlight weak anomalies，and then lighting analysis is carried out in different orientations to extract non-seismic anomalies that can reflect the strike-slip fault.The results can be used to explain the horizontal distribution of the strike-slip fault.In the case of the ‘continuous axis but breaking layer’ phenomenon on the seismic reflection layer，or in other words，the same reflective layer reflects different strata，the time-frequency electromagnetic interpretive processing technology is used to identify the strata attributes after the precise inversion of the target layer，and the result of comprehensive analysis of various information makes the stratigraphic attribution more accurate.For the deep strata where seismic reflective imaging is difficult to realize，gravity–seismic combined stripping can be applied to Lower Paleozoic strata，and the results can be used to predict the deep source rocks of the Changchengian system. 2023 Vol. 58 (6): 1481-1488 [Abstract] ( 52 ) [HTML 1KB] [ PDF 7975KB] ( 156 ) 1489 Applicable conditions and effects of remote reference method of magnetotelluric electric field WANG Peijie, CHEN Xiaobin, ZHANG Yunyun, YANG Jing, DONG Zeyi The remote reference method is effective for processing magnetotelluric （MT） time series data.It is generally believed that magnetic fields yield better effects as reference channels，but electric fields are not suitable as remote reference channels due to their susceptibility to underground structures.Based on actual data processing，this paper explores the utilization of electric fields as reference channels for processing MT data and finds that they perform well in the high-frequency range above 1 Hz but poorly in the low-frequency range.Then，it puts forward a new approach that employs electric fields as reference channels for processing high-frequency data.Fine processing of audio magnetotelluric （AMT） data confirms the validity of electric fields as reference channels in the high-frequency range （> 1 Hz）.Application of this approach to AMT data processing indicates that the results obtained by adopting electric fields as reference channels are comparable to those by utilizing magnetic fields as reference channels，with sound improvement in data processing of AMT “dead band”（1k~5k Hz）.AMT data collection typically involves multiple measurement points sharing a set of magnetic channels，and the electric channel number greatly exceeds that of magnetic channels.Thus，processing of remote reference channel electric fields can significantly improve AMT data processing results and can be popularized as a conventional processing method.Analysis of natural source electromagnetic fields and MT dimensionality parameters shows that the limited influence of high-frequency electric fields on underground structures is the underlying reason for the remote reference channel data effectiveness of electric fields.This research also provides guidance for the location selection of remote reference stations，suggesting that the stations should be situated in areas with simple geoelectric structures to minimize interference of underground electrical structures on natural electromagnetic field signals from the same source as the survey area. 2023 Vol. 58 (6): 1489-1498 [Abstract] ( 53 ) [HTML 1KB] [ PDF 2529KB] ( 176 ) REVIEW 1499 Progress and prospects of brittleness research in unconventional reservoirs LIU Zhen, ZHANG Junhua, YU Zhengjun, REN Ruijun, SUN Youzhuang This paper briefly reviews the current domestic and international research status and influencing factors related to brittleness. On this basis， we summarize seven main expressions for brittleness indices and expound upon their respective physical interpretations. Brittleness prediction methods for reservoirs are categorized into seismic brittleness inversion based on conventional approaches and brittleness prediction based on deep learning techniques. Meanwhile， the advantages and disadvantages of the two methods are evaluated. Conventional methods are characterized by wide applications， relatively mature algorithms， stability and reliability， and requirements for substantial prior knowledge with limited effects in complex geological conditions. Conversely， deep learning methods feature adaptability to intricate geological conditions， no need for prior information， and straightforward principles and procedures. However， the training process demands significant computational resources and time. Additionally， we introduce new technologies such as direct inversion of Bayesian AVAZ brittleness， machine learning brittleness prediction based on well-logging derivatives and volatility attributes， and hybrid neural network brittleness prediction by employing CNN-LSTM models. Finally， this study provides an outlook on the future development of brittleness prediction techniques. 2023 Vol. 58 (6): 1499-1507 [Abstract] ( 66 ) [HTML 1KB] [ PDF 4508KB] ( 211 ) 1508 Research progress on fracture detection technology of hydraulic fracturing based on electromagnetic methods MENG Jin, LIU Dejun, ZHAI Ying, LI Yang, LIU Sitong, PENG Na Hydraulic fracturing is an important tool to improve the production of stratigraphic oil and gas reservoirs， and is of significance to the exploration and development of oil and gas fields. Hydraulic fractures are the main see-page channels and effective storage space for oil and gas reservoirs， and fracture identification is an important link in exploration and development. Scholars have proposed many practical technical solutions for hydraulic fracture detection by electromagnetic methods. Firstly， this paper classifies and summarizes the main geometric shapes of hydraulic fractures from the perspective of spatial development， and analyzes the advantages and disadvantages of electromagnetic monitoring methods for hydraulic fractures. Based on induction logging theory， new methods and technologies for monitoring and identifying hydraulic fractures filled with conductive proppants by electromagnetic methods are introduced. Secondly， the research status and development trend of hydraulic fractures are reviewed in detail of vertical wells， horizontal wells， and multiple wells. Finally， the main problems and difficulties in electromagnetic detection research on hydraulic fractures are discussed. Currently， the main technical difficulty is that it is hard to master complex fracture morphology， and fracture morphology research is affected by many factors. Thus， multiple electromagnetic simulation methods should be combined for the distribution and characteristics of hydraulic fractures with multi-scale characteristics. 2023 Vol. 58 (6): 1508-1521 [Abstract] ( 120 ) [HTML 1KB] [ PDF 4224KB] ( 150 ) 1522 Progress on joint inversion of electromagnetic constraints combined with multiple methods and multiple information ZHANG Shuoning, YU Guo, HE Zhanxiang Electromagnetic exploration plays an important role in oil and gas exploration，deep mineral resources survey，geothermal groundwater exploration，imaging of deep earth structures，and underwater military target reconnaissance.This paper systematically summarizes the research progress on joint inversion of electromagnetic constraints combined with multiple methods and information，introduces the research status from the perspective of method application，and focuses on the construction form，existing problems，and technical difficulties of the objective function for different inversion methods.In areas with more known information such as seismic data，different types of constraint functions are constructed by utilizing priori information to improve the tectonic imaging accuracy in saline and igneous rock development areas and reduce the inversion non-uniqueness.In areas where the magnetotelluric （MT） and controlled source electromagnetic （CSEM） data have been collected，the two methods can be employed to carry out joint inversion with their respective advantages.Various forms such as joint inversion with sequential constraints and joint inversion based on a unified objective function are developed.Additionally，CSEM and MT make up for each other in-depth inversion to improve the target inversion accuracy and reduce non-uniqueness.This paper discusses the selection of objective functions and weighting factors for this type of joint inversion.According to actual application effects，the most important and potential joint inversion is the inversion of electromagnetic and seismic data.Joint inversion has gone through from seismic constrained electromagnetic inversion to physical model-based and cross-gradient method-based joint inversion.This paper also analyzes the difficulty in constructing a reasonable connection between velocity and resistivity models and explains that the weighting factor setting of velocity and resistivity models in the objective functions is still the key and difficult points.Finally，this paper proposes to combine electromagnetic joint inversion，artificial intelligence algorithms，and three-dimensional visualization analysis.It also points out that large-scale parallel computation and other new methods and technologies can be adopted in the future，and joint acquisition systems can be developed to provide more effective data volumes for the multi-physical field joint inversion. 2023 Vol. 58 (6): 1522-1534 [Abstract] ( 68 ) [HTML 1KB] [ PDF 1913KB] ( 164 ) PESONEGY 1535 Geophyisist LIU Yike 2023 Vol. 58 (6): 1535-1535 [Abstract] ( 60 ) [HTML 1KB] [ PDF 334KB] ( 237 )

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