The periodic layered porous media is used to present the fractured porous media with mesoscopic inhomogeneities.Based on quasi-static poroelastic theory and White model,the effective medium model of P-wave propagating normal to the layer is given.The thinner layer in the periodic layered porous media can be substituted by a very thin and highly compliant layer to model fractures in a porous background.Compared with linear-slip fracture model,a dispersion equation for a P-wave propagating normal to fracture is given.The magnitude of velocity dispersion and energy attenuation of P-wave caused by wave induced pore fluid flow between pores and fractures are apparently larger than that of Biot fluid,and their peak value often lies in the seismic frequency band.The magnitude of velocity dispersion and attenuation of P-wave will increase monotonically with the increase of fracture weakness (fracture density).The characteristic frequency of the attenuation and velocity dispersion of P-wave depends both on the permeability and fluid viscosity of background porous media and on the fracture weakness and spacing.

 Full waveform inversion(FWI)is one of the hot issue in the geophysics exploration. The new round study involvees in many deeper issues,such as wavefield simulation,gradient estimation,data pre-processing,objective function and so on. Those further studies reveal the limtations of geometry and seismic data, as well as the potiential of FWI,through an overall investigation on the FWI theory,technology and application status,we introduce FWI development,from time domain to frequency domain and Laplace domain,especially to the hybrid domain. It is shown that FWI has been already successfully used in the marine data,however it is still a challenge in land data application;bottlenecks of the land data application are analyzed,such as limitation of geometry,lack of low-frequency component of data,the challenge of data pre-processing,the near surface conditions and source-receiver limitation of land acquisition;Finally it is concluded that step-by-step hierarchical multi-scale strategies and combination of different methods would be available to realize the land data FWI application.

Rock physical model is an important basis of petrophysical research and S-wave velocity estimation.Based on Xu-White sand-clay mixed model,by using core testing data,P-wave and density log,clay content and porosity measurement,we calculated bulk and shear modulus of dry rock;then,the effective elastic modulus in different fluids with different saturation was calculated;finally,the P-wave velocity and S-wave velocity were computed.By comparison with actual density and P-wave data,we constantly modified parameters and carried out iterative computation.By this means,the S-wave velocity can be obtained.Through S-wave velocity estimation by using rock physical model,the problem of missing S-wave data in conventional logging data of Fangheting structure in Pinghu Gasfield was solved,which provided reliable basic data for AVP forward modeling and pre-stack AVO/AVA simultaneous inversion.

The full waveform inversion (FWI) method makes use of the kinematic and dynamic information of pre-stack seismic data to rebuild underground geophysical parameters.Due to its high resolution,it has the potential of revealing structure details and lithology characteristic under complex geological background.We present some methodological and algorithmic developments of 3D acoustic full waveform inversion by frequency-domain inversion combined with time-domain forward.The FWI algorithm relies on a pseudo-conservative form of the velocity-stress acoustic wave equation.The numerical simulation data of 3D SEG/EAGE target model verified 3D acoustic full waveform inversion algorithm.

P-wave velocity and S-wave velocity are two important parameters in reservoirs evaluation and fluid identification.Well log is an efficient approach to obtain these parameters.Velocity inversion based on rock physics model is proposed for the case of a lack of velocity logging data in exploration.Firstly,we introduce the relationship between velocity and porosity and velocity estimation process based on rock physics model,and then establish the rock physics relationship between logging data and rock elastic parameters on the basis of rock pore parameters.Finally,we reconstruct objective function and obtain reliable P-wave and S-wave vecolities by simulated annealing inversion.The results based on experimental data and actual logging data show P-wave and S-wave predictions based on rock physics model are reliable without velocity logging data as priori constraints,which offers an efficient method for accurate reservoir evaluation.

Fracture identification and prediction is significant in hydrocarbon exploration. Corresponding theory and experiments have
shown that the anisotropy caused by fracture will affect seismic reflection features during wave propagation. For this
reason,it is feasible to characterize fracture trend,intensity and distribution by using seismic data. For fracture
prediction,seismic technology is characterized by low cost,extensive coverage area and large probing depth compared with
other methods,which can be divided into three types,including multi-component converted-wave fracture
characterization,azimuth anisotropy detection of P-wave response and post-stack seismic attribute analysis. Various
techniques have different popularity and efficiency because of the difference from data source,data requirement and technique
maturity. With the development of surveying and processing techniques,multi-component converted-wave fracture
characterization and azimuth anisotropy detection of P-wave response will be more widely used in fracture characterization.
For the same reason,seismic attribute anomaly detection will also be more important in using various dataset to recognize
fractured reservoirs.

Petrophysical parameters inversion based on geophysical data is an important step in reservoir prediction and comprehensive evaluation. We proposed a new petrophysical parameter inversion method based on Bayesian classification. This method involves multiple theories and techniques, such as statistical rock physical model, Monte Carlo simulation technology. The posterior probability distribution of petrophysical parameters is calculated based on Bayesian classification algorithm and can realize multiple petrophysical parameters joint inversion based on Bayesian inversion framework. This method does not need to carry out complex model initialization. It obtains the relationship between petrophysical parameters and elastic parameters through statistical rock physics model, and then combined with pre-stack seismic inversion. This method can not only simulate geophysical stochastic properties, but also can well solve the problem of excessive dependence on log data in conventional petrophysical parameters inversion methods. The practice shows that it can provide various petrophysical parameters for fine reservoir description and quantitatively evaluate the errors of inversion result.

在研究前三代地震相干算法的基础上，提出了一种基于地震数据结构张量的相干属性计算方法和流程。该方法将地震数据瞬时相位作为数据输入，利用复地震道数据信息对地震数据结构张量的偏导数求取进行平滑处理，较好地解决了由于地震资料中噪声的存在而产生的计算不稳定性，且利用纵、横向的瞬时波数计算可以得到地震数据的视倾角和方位角属性体。实际三维地震数据的计算结果验证了地震数据结构张量相干计算方法的有效性，计算出的相干属性体分辨率更高，断层的展布形态更清晰。

塔里木盆地顺托果勒西区块中下奥陶统碳酸盐岩储层埋藏深度大，非均质性强，岩体孔缝洞发育，但规模总体较小，井-震响应关系复杂，“串珠”状反射不明显，储层预测难度大。在地震反射特征和岩石物理分析的基础上，综合利用地质、地震和测井等资料，进行研究区奥陶系储层地震波阻抗反演，在有利区寻找低阻抗对应的缝洞发育线索，识别以蜂窝状密集分布但不足以形成“串珠”反射的小尺度、非规则溶蚀孔缝洞，结合敏感地震属性的综合分析，预测顺西区块奥陶系有利储集体的分布规律，为优选勘探目标提供依据。

Through-wall imaging techniques with Ultra-WideBand (UWB) radar are promising candidates for non-destructive detection, especially in disaster areas like calamity rescue scenarios, counter-terrorism and so on. These applications always require high-resolution target imaging to identify the object shape. Based on this requirement, a complex target boundary imaging algorithm for UWB radar is proposed to realize the shape estimation and identification of the target behind walls. As the application is a near field problem, the algorithm offsets the influence from walls using the incident angle of the radar echo calculated by the time-delay difference curve, and estimates the target boundary effectively. Simulation and experimental results of targets behind walls with different shapes show that the proposed algorithm can remove the influence from walls, estimate the target boundary effectively and realize the basic target identification.

In order to confirm the effectiveness and application value of high-frequency information outside of seismic wave pass band for sand body prediction, the convolution model was used to verify that seismic wave high-frequency is the basis of fine delineation of geological body spatial structure for sand body. De-noising processing is the key of retaining high-frequency information in the course of seismic data processing flow. We put forward the methods, which on the minimal impacting effective signal conditions, utilizing Curvelet transform that is characteristic by minimal overlap in Curvelet transform domain for effective signal and noise, attenuate noise and retain effective high-frequency components of seismic wave, and using the adjustable flexible and aggregation time-frequency properties of self-adapting S transform (SAST) to extract high-frequency information, obtaining high-quality single-frequency data for sand body prediction. The processing result on actual data in TH area showed along horizon lateral iso-frequency slices of high-frequency. Meanwhile, outside the pass band, the spatial distribution and boundary of the sand body was clearly depicted.

Wide azimuth seismic is a kind of 3-D seismic data acquisition-processing technique with the ratio between transverse and
longitudinal receiver unit larger than 0.5. Wide azimuth seismic is characterized by whole distribution of azimuth angle and
even distribution of offset. Thus wide azimuth seismic data contains more information,which is helpful for identifying micro
-relief structure,small faults and high-angle fractures. We introduced the wide azimuth seismic acquisition and processing
examples in Luo42 area and Shang741 area of Jiyang Depression,and Zhuang1 well area in central Junggar Basin. Moreover,wide
azimuth seismic data was applied for predicting shale fractured reservoir and igneous rock fracture development belt,as well
as characterizing the sand bodies in Zhuang1 well area. Results indicate that wide azimuth seismic is effective for the
geologic bodies with anisotropy and strong heterogeneity,but there is no advantage for identifying sand bodies and inversing
physical properties by using wide azimuth seismic data when the geologic target of reservoir prediction is sand bodies and
the reservoirs without strong anisotropy.

To detect the tilt fracture of carbonate reservoirs in Tahe Oilfield,fracture prediction technique based on P-wave residual time-difference of TTI model with tilt axis symmetry is developed and validated.The basic theory of TTI media and NMO residual time-difference are reviewed and the phase velocity of P-wave in 3D TTI media is computed.A fracture prediction technique for P-wave residual time-difference applied for prestack seismic gathers is developed,of which the technical procedures and steps are shown in details.A three-layer numerical model containing one TTI fracture interlayer is designed,with which synthetically seismic azimuth gathers are simulated with finite difference method.The fracture development intensity and fracture angles are inversed by extracted NMO residual time-difference,which are almost the same with the model design parameters.It validates the fracture prediction technology using P-wave residual time-difference based on TTI model.

Matching pursuit time-frequency characterization method based on traditional Morlet time-frequency atoms dictionary cannot adjust the time-frequency resolution, which limits the application on actual data. In order to solve the problem, we introduced resolution adjustment parameter to make the time-frequency resolution of Morlet wavelet flexible and controllable. On this basis, the variable resolution matching pursuit time-frequency characterization method was developed to realize adjustable for time resolution and frequency resolution. In the spectrum imaging of thin reservoir, our method was used to enhance the time resolution of matching pursuit time-frequency distribution, which can effectively avoid the interference of complex geological background and achieve a clear image of thin reservoir.

The paper described comprehensive 3D seismic data interpretation. The author pointed out that interpretation of seismic section should be performed using sequence stratigraphy and techniques of balance section, under the guidance of structure styles and filling model, and the resulted interpretation then be converted into geology interpretation by using well and field geology data. Interpretations should be verified by model computation and balance section technique. Desired results have been achieved by applying the method in the interpretation of complex structures in Biyang Depression.

Local structures are the places where hydrocarbon concentrates in basins. The study of geometry, genesis, and spatial distribution of the local structures helps to understand the regularity of hydrocarbon concentration and characteristics of hydrocarbon reservoirs, which are valuable information for the success of drilling. This paper summarizes the basic regularities of local structures in Zengmu Basin, Beikang Basin, and Nanweixi Basin, and studies the configurations of local structures and the types of hydrocarbon traps. The author believes that the south part of South China Sea has a regional tectonic setting that is favorable for the growth of local structures. The local structures in different sedimentary basins are closely related to fault controls. The configuration of local structures and trap types are controlled from the positions of the local structures and the degree of reformation from regional tectonic movement.

 Research of oil and gas artificial intelligence can be divided into two levels,academic and industrial research,which faces different problems and challenges.Academic oil and gas artificial intelligence application scenarios are mainly concerned with algorithms and their related theoretical applications,focusing on solving the local problems of intelligent points.Industrial-grade artificial intelligence applications are mainly concerned with data sets,platforms,multi-source multi-scale data fusion modeling,data-driven and mechanism model fusion modeling,and machine learning model explanatory issues.In this study,three suggestions are put forward for data-driven and mechanism model fusion:algorithm fusion,evaluation method fusion and data set fusion,and experimental verification is given.In view of the problems of oil and gas artificial intelligence models,the author illustrates that industrial-grade oil and gas artificial intelligence must be explanatory and puts forward some preliminary solutions,including multi-level interpretation,pre-modeling,in-modeling,and post-modeling.Finally,the author suggests that,to explore the development of industrial-grade artificial intelligence theory and application scenarios,we must clarify the interaction between the “physical world,” “digital world,” “the world recognized by humans,” “the world recognized by machines,” and “the world in which machines are being transformed.”

 Compressed sensing (CS) has been given full attention in the domain of oil and gas seismic exploration.The idea of CS is mainly implemented in two aspects,one is random-sampling based applications,such as seismic acquisition design and evaluation,de-blending of simultaneous-source data,regularization of seismic data,denoising and compression of seismic data; the other is the characteristic expression of data and model parameters,and the corresponding forward modeling and sparse inversion methods (including multi-scale inversion).The former one can be solved by using various methods developed in signal and image processing fields while the latter one need geophysicists to develop new ideas and methods.Both the reflection scattering waves and layered models are compressible,which make is possible for the successful application of CS in exploration seismology.The basic idea of CS is concisely sketched and it is pointed out that CS is a theoretical frame of random sampling.And then we demonstrate that both the prestack seismic data and its migration results can be sparsely expressed.CS can be reasonably used in seismic exploration.We show its applications in random sampling,de-blending of simultaneous-source data and regularization of multi- dimensional seismic data.It is indicate that the current seismic data acquisition technology development should be focused on how to truly implement the so-called “broadband and wide-azimuth and high sampling density” seismic data acquisition.At last,the application of CS in characteristic data extraction,encoding shot gathers imaging and characteristic wavefield imaging are enumerated.

The formation quality value Q reflects the absorption and attenuation characteristics of medium,which is an important parameter for gas detection.When the geologic conditions are complex,for example,existing high-impedance geologic bodies such as igneous rock,it is difficult to distinguish the strong amplitude caused by gas or high-impedance geologic bodies.In order to solve the problem,firstly,pre-processing is carried out on seismic data by using the similar background separation technique to remove the information irrelevant to stratigraphic characteristics. Then,time-frequency spectrum in S domain is obtained by applying the S transform on pre-stack seismic data,combined with spectral ratio method in S domain,the slope of spectral ratio.Finally,by linear regression we can obtain the Q value of zero-offset seismic data.This method makes full use of the advantages of the pre-stack seismic data containing more information than the post-stack seismic data and high time-frequency resolution of the S transform.Moreover,the method was applied to extract the Q value of actual seismic data.The results show that Q values in the gas-bearing zone are relatively low and anomalies are obvious;on the contrary,in the non-gas-bearing zone such as high-impedance geologic bodies,Q values are relatively high,and there is no anomaly.Thus,the technique can better reflect the absorption characteristics of formation and improves the prediction accuracy of gas-bearing reservoir.

Seismic migration started out with a humble goal:trying to position lateral subsurface reflectors accurately enough for exploration with a drill bit.Over time,migration became more ambitious.With the advent of prestack depth migration,we began to think of seismic imaging as a process to provide a picture of the interior of the earth.We give an overview of prestack depth migration,its theoretical foundations,application status,and technological evolution in response to production demands.Based on true amplitude migration theory,we review all the main trends of depth imaging techniques,such as Kirchhoff migration,beam migration,and one-way wave equation migration.Particularly,we focus on reverse time migration (RTM),introducing its theory and applications.We address a few important topics in RTM development,such as common imaging gather output,anisotropic migration,anelastic attenuation compensation,migrating simultaneous shooting records,ghost compensation within an RTM,and the imaging of multiples.We then discuss the theory of least-squares migration (LSM),its implementations,and the main practical issues,and compare migration deconvolution with LSM.Full waveform inversion (FWI) has been a hot topic in exploration geophysics in the past decade.We show that true amplitude migration theory plays an important role in building up the connection between imaging and inversion,and an inversion-based true amplitude RTM stays as the kernel of a FWI.We discuss several challenging topics in FWI implementation,such as cycle skipping caused by missing low frequencies in data,FWI based on only travel-time information,reflection-based FWI,and multi-parameter FWI.Much progress has been made to solve those problems.A fully automated FWI will significantly simplify processing workflow,greatly reduce production cost,and improve imaging resolution.More importantly,it will help geophysicists to approach the ultimate goal:rendering quantitatively accurate earth models with high resolution.

In accordance with the characteristics of Putaohua oil reservoir of thin deltaic interbeded sedimentary layers in Songliao basin, we study the relation among sandstones of different microfacies log characters, and seismic attributes to try qualitatively predict the sandstone reservoir development zone in terms of sedimentary microfacies and waveform characters. It is concluded that there is high degree of correlation between the total thickness of sandstone oil reservoir and seismic attributes. Thick sandstones can be predicted with high reliability and the thickness of sandstone reservoirs is predicted.

By the development and application of high-precision seismic,reverse-time migration,seismic attributes analysis and seismic inversion,etc,SINOPEC has achieved good results in the fine exploration at mature oilfields and exploration breakthroughs in new areas,especially in fine characterization for complex faulted blocks,continental sandstone lithologic reservoirs identification,marine carbonate reservoir characterization,tight sandstone reservoir detailed prediction and shale gas comprehensive evaluation,etc.However,some challenges exist in the hydrocarbon exploration for SINOPEC,including unidentified scaled strategic replacing resources,difficult in natural gas exploration,deep-buried and lower-grade new added reserves,and engineering techniques lacking in supporting seismic exploration.Facing the challenges and difficulties,in the hydrocarbon exploration of mature oilfields,on the one hand,we should focus on the development of high-precision seismic,reservoir geophysical techniques,continuously improve the identification and characterization precision of complex geological bodies,and strengthen the reliability of complex reservoir evaluation;on the other hand,we should carry out the research of high-efficiency environmental protection geophysical techniques,innovatively apply equipment manufacturing,information technology,computer technology,reduce the hydrocarbon exploration costs.In the hydrocarbon exploration of new areas,the basic seismic theory research should be deepened to explore the shooting and receiving rule for seismic signals in complex exploration areas;the innovation of geophysical technology should be strengthened,especially on overcoming the seismic acquisition technical problems at the areas with extremely complex surface conditions and subsurface conditions,to improve the quality of seismic data with low S/N,and prove powerful technical support for hydrocarbon discovery.

通过分析研究8L4S176T正交束线观测系统及其在复杂滩浅海区域施工时对接收设备、震源激发、二次定位和采集方法的要求，论证了该观测系统对于实现以提高中深层复杂构造成像精度和分辨率、衰减采集脚印为目的的地震采集在复杂海底应用的可行性。正交观测系统横向一次只滚动一个排列，有效避免了采集脚印的产生；根据不同水深采用不同的激发和接收方式，提高了轻型海底电缆地震资料的品质；声学定位、沿检波线激发等措施保障了采集效率。实际应用结果表明，该观测系统及其采集方法有效提高了地震资料信噪比，获得了更加丰富的波场信息，改善了成像精度。

地震勘探装备和技术的飞速发展为高密度单点地震采集技术的应用提供了可能。通过对比分析贵州中部某山区盒子波资料、单点采集与组合接收野外试验资料以及叠加剖面，探讨了单点采集与组合接收的差异性。研究表明，组合接收会造成地震波主频降低，进而会影响叠加剖面的分辨率；单点采集有利于保护有效波的频率成分，但地震资料的信噪比较低。

According to apparent absorption and attenuation characteristics of the hydrocarbon-bearing reservoir, a characteristic attribute reconstructing method based on seismic wave attenuation has been developed to identify the reservoir fluids. The seismic absorption and attenuation theory is the foundation of this method. A seismic characteristic attribute function has been deduced by changing the strata quality factor expression. According to this function, we reconstruct new seismic attributes by using the common seismic attributes of amplitude class, frequency class and absorption & attenuation class. Based on the designed viscoelastic medium model, the examine result shows that the new attributes can emphasize the changing characteristics of reservoirs fluid-bearing and verify the new method. Applied the technique to Lao168 well block to identify the reservoir hydrocarbon-bearing of channel sandstone, we achieved a good result that the distribution of the fluid was accurately depicted.

Prestack time migration (PSTM) is useful in imaging and velocity analysis.Amplitude-preserving prestack migration before amplitude versus offset (AVO) can improve the AVO analysis effectively. We present a 2D frequency-wavenumber constant-offset prestack time migration algorithm, which can not only make better imaging of reflectors with steep dips and preserve amplitudes correctly, but also has high computation efficiency. Velocity analysis is performed on common image point (CIP) gathers after migration.

陕北富县黄土塬侵蚀地貌区地表巨厚的黄土盖层沟壑纵横，高程变化剧烈，复杂的近地表结构、严重的高频吸收衰减和多种类型的干扰波，导致常规处理方法获得的地震资料信噪比和分辨率较低，无法满足后续地震成像处理和储层预测的需求。针对黄土塬区复杂地表静校正难题，提出了“先低频、后中高频，逐步逼近”的静校正思路并取得了明显效果；针对该区噪声类型多、分布范围广的特点，采用“多域联合，先强后弱”的串联去噪配套技术进行叠前高保真噪声衰减；利用保持振幅的一致性处理技术，消除地震资料的振幅、频率差异，统一资料的品质；通过三维地表一致性反褶积和叠后进一步拓宽频带处理，提高地震资料的分辨率。处理结果表明，研究区地震资料的信噪比、分辨率和保真度得到了有效提高。