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.

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.

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.

The conventional seismic inversion imaging is divided into migration velocity analysis (MVA) and tomography,prestack migration imaging and AVA analysis/inversion.The key techniques in the three inversion imaging methods are the core technologies of modern exploration seismology.Full waveform inversion (FWI) is a complete theoretical framework of seismic inversion imaging,and which can roll up the three conventional inversion imaging methods into one and give a desired imaging result in principle.However,due to the incompleteness of pre-stack seismic data,imperfectness of forward model,inaccuracy of initial model,unknown and spatial variation of seismic wavelet,the practical problems have not yet been solved with FWI method in the strict sense.In this paper we analyze the existing problems of classical FWI method and propose a practical seismic inversion imaging workflow,that is to divide classic FWI into transmissive wave tomography,LS-PSDM imaging and reflections tomography.Aimed at the features of land seismic data,we point out that the establishment of shallow velocity model,background velocity model,velocity model for CIG tomography,LS-PSDM imaging,generation of the incident angle gather and dip angel gather,impedance inversion by small angel CIG gathers are crucial for the promotion of the application and self-development of FWI technique.

Global warming has become a major challenge to human survival and sustainable global development, whereas carbon neutrality and green low-carbon development have become the common consensus and path of action in nearly all countries.The capture, utilization, and storage of carbon dioxide and other greenhouse gases that cannot be reduced is an indispensable technical approach, key backing technology, and final means to achieve the goal of zero carbon or even negative carbon on the path of green low-carbon development.It is also an important supporting technology for the clean use of fossil energy and a key technology in building tenacious and elastic energy systems.Geological carbon sequestration has great potential for large-scale and commercial application, and has a long period of time for technical exploration and demonstration application basis.Geophysical technology plays a unique and indispensable role in the geological storage of carbon dioxide and mainly includes three aspects: the selection and evaluation of geological carbon storage sites, monitoring and evaluation of the effectiveness of geological storage as well as geological storage safety.Geophysical monitoring of geological carbon storage is mainly based on time-lapse geophysical methods, which implies that dynamic monitoring of the carbon storage process is achieved through repeated geophysical observations.Geophysical methods are mainly seismic, including 3D seismic, cross-well seismic, borehole seismic, and microseismic methods; as well as other methods such as satellite remote sensing, time-lapse electromagnetics, time-lapse gravity, and logging.Compared with that of petroleum exploration, the application of geophysical monitoring technology in geological carbon sequestration has special requirements including permanence (long-term repeated and continuous monitoring), dynamics, and low cost.Nevertheless, it still faces a series of technical and economic problems and challenges.Geophysical monitoring technology for geological carbon sequestration is not yet optimal, and requires further improvement and optimization to achieve a comprehensive balance in terms of effectiveness, efficiency, and economy.The joint application of various geophysical monitoring technologies, the permanent deployment of DAS and seismic nodes, passive microseismic monitoring, automatic processing, and intelligent analysis are important future development directions.

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.

 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.”

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.

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。

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 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.

In seismic exploration,because of lack of knowledge on geophone principles and performance there are some improper behaviors about the choice and use of geophone.The relationship between geophone parameters and response characteristics is not clear,as well as the impact of these parameters on seismic signals,which lead to not strong pertinence in comparison test and utilization of geophones.Therefore according to the vibration mechanics theory of geophone,the frequency response characteristics of displacement,velocity and acceleration geophone was analyzed,and the different electromechanical transform principles were elaborated.On this basis,we further analyzed the effect of geophone characteristic parameters on seismic signals and the requirements on geophone performance and parameters in seismic exploration.According to the characteristics of the shock and vibration signal in seismic exploration,it is shown that the geophone with wide frequency band,big dynamic range,small distortion,high sensitivity and small tolerance can satisfy the need for seismic exploration.Meanwhile,the actual use of geophone has been discussed,in particular the problems in geophone comparison test.Comprehensive analysis indicates that only by mastering the principles,performance and parameters of geophone we can properly select and use geophone

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 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.

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.

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.

 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.

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.

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.

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.

Every progress of geophysical exploration techniques in history brings fast increase of hydrocarbon reserves.High-precision seismic exploration technique will inevitably become the main technical means for another great increase of domestic hydrocarbon reserve.We reviewed the first high-precision seismic exploration case in Tianjia area,elaborated its historical position,and showed that its ideas of 3-D high-precision exploration affected the development path of high-precision seismic exploration technologies in Shengli Oilfield and in SINOPEC continuously.The development level of high-precision seismic exploration technique in SINOPEC was analyzed;its application status and application effect was overviewed.Aiming at the exploration requirements in submit reservoir,marine carbonate and piedmont zone,development direction of high-precision seismic exploration technique was proposed,that is continuously promoting and applying 3-D high-precision seismic technique,positively carrying out prior test and innovatively studying corollary processing and interpretation methods for 3-D high-density seismic technique.

Frequency-dependent amplitude attenuation method divides seismic data into different frequency band.Strong-energy noise can be identified by calculating amplitude strength of sampling points within the given frequency band and time window.The amplitude attenuation curve of the seismic sampling could be achieved by calculating every sampling’s amplitude strength which is calibrated by the average absolute amplitude of the seismic sampling group.Then,the strong-energy noise can be effectively suppressed by applying time-variable threshold.The method is applied for noise elimination processing to offshore seismic data in the East China Sea,which shows that the method can completely suppress swell noise,seismic vessels interference and strong-energy noise with high or low frequency,and effectively suppresses the remaining multiples in near traces with great improvement of the S/N of offshore seismic data.