Structural and stratigraphic reservoirs characterized by simple structure and complex lithology are becoming major targets for oil and gas exploration. The difficulties of this kind of reservoirs in exploration are the accuracy of the structural and depositional interpretation of the reservoir, the accuracy in velocity estimation as well as seismic resolution limitation. To deal with these problems, a seismic exploration study for a structural and stratigraphic reservoir in PY Oilfiled, Zhujiankou Basin is carried out. The main problems for PY Oilfield are such as abrupt change of water depth and Quaternary system depth, spatial variation of the velocity field, imaging in gas cloud area, seismic resolution, as well as accuracy of structural and depositional interpretation. The study proves that: multiple attenuation, resolution enhancement with relative amplitude reserved, high precision velocity estimation, isochronous structural framework interpretation, depositional evolution and architecture of sand bodies interpretation, as well as structure mapping with integration of seismic and well logging are critical techniques in structural and stratigraphic reservoir exploration. Lately drilled development wells in the oilfield verify that the depth error of the interpretation is less than 0.1 % for target reservoirs at 3000 m depth.

Based on the principle of seismic structural properties, we elaborate in this paper the definition and characteristics of grey level co-occurrence matrix (GLCM), and propose calculation methods of seismic structural properties.Then we convert images of seismic wave to chromatic difference images with clear geological meanings (energy, entropy, contrast & homogeneity) to identify complex geological units.The application in west slope of Damintun Sag shows that faults can be identified by the contrast attribute, and lithological sedimentary bodies can be recognized by the entropy attribute.All this interpretation coincides very well with the drilling data.So the seismic structural properties analysis can be used in a joint interpretation as a new approach to identify fautt systems and lithological sedimentary units.

An anisotropic velocity analysis based on shift hyperbolic equation is proposed in the paper.In the light of non-elliptical feature of shift hyperbolic NMO formula,this paper discusses the relation between shift parameter and non-ellipse parameter.Two restrained parameters describing reflection hyperbolic curve in local coordinate system are introduced,and related computing formula is deduced.This process sequence of anisotropic highdensity velocity analysis solves NMO problems which cannot be corrected at far offset gathers by NMO,and improves the imaging of prestack time migration.Different examples show that the method can accurately correct far offset reflection wave, and provide high quality CRP gathers for prestack inversion.

Fracture characterization based on azimuthal anisotropy of P-wave amplitudes has been widely used to predict fracture density and azimuth.However,the fracture characterization method based on the amplitude anisotropy often encounters some problems in practical applications.The most serious one is that the prediction results of fracture density are largely influenced by cave and are insensitive to multi-orientation fractures.As a result,this fracture characterization method based on the amplitude anisotropy cannot obtain satisfactory results when dealing with complex fracturedvuggy carbonate reservoirs.To solve this problem,the paper proposed a new method for fracture characterization based on the anisotropy of anttracking attribute volumes to improve the performance on fracture characterization.Firstly,we get the distribution zones of fracture by multi anttracking results and fracture distribution regularity.Then,we can get the fracture density and azimuth based on anisotropy of P-wave amplitudes in the fracture-developed zones.The proposed method solves the problem of influence of cave and insensitivity to multi group fractures.In addition, the proposed method resolves the problem of only producing incomplete fracture distribution maps of the conventional ant-tracking algorithm.Application results to real datasets indicate that the proposed method can accurately characterize complex fracture-vuggy systems and give a quantitative description of fracture density.

Time-frequency analysis can be used to time-frequency decomposition of seismic waves,and thus to obtain absorption attenuation gradient of high-frequency for hydrocarbon detection.However,when there is strong high-frequency interference in seismic records,the absorption attenuation gradient of high frequency is not a very good response to the real absorption attenuation of layer.In this paper,we take the advantage of higher time-frequency resolution of the generalized S transform and use the time-frequency spectrum to obtain seismic absorption attenuation gradient of low-frequency,then compared with the absorption attenuation gradient of high-frequency to better direct hydrocar bon.Results of theoretical derivation,numerical simulation and field data application show that generalized S transform based on absorption attenuation gradient detection of low-frequency and high-frequency can mutually support,and better point the existence of hydrocarbon.

This paper analyzes the structural features ofMeso-Cenozoic typical transfer zones in Jiuquan Basinand discusses transfer zone’s oil-controlling based onseismic and outcrop data. Extensional transfer zones inearly Cretaceous are divided into four types includingsynthetic overlapping, synthetic collateral, conjugateddivergent overlapping and transverse fault type. Com-pressional transfer zones in Cenozoic are divided intotwo types:transverse-slip fault and tear fault. Theyare mainly distributed in the south marginal piedmontfold-thrust belt, and perpendicularly developed to thisbelt, which play the role of compressional deformationand displacement. The transfer zones control on for-mation of hydrocarbon accumulations. The extensionaltransfer zones not only play an important part in struc-tures and traps developing in the rift basin, but alsocontrol the distribution of provenance and sedimentarysystem, and thus control the hydrocarbon gatheringand distribution. As hydrocarbon migration paths, thecompressional transfer zones improve reservoir physicalproperties and they are also rich oil-gas belts in QingxiOilfield.

Wide azimuth data acquisition leads a few problems in data processing,such as velocity variation with azimuth,azimuth-dependence travel time correction,azimuth-dependence anisotropy.For wide azimuth data(not full azimuth data),it is very crucial to form reasonable azimuth sectors which are favorable for processing and interpretation from real data.In this paper we propose a set of solutions including azimuth sector forming,azimuth accurate stack velocity estimation;azimuth-dependence travel time correction and azimuth anisotropic pre-stack migration.Improved results have been achieved with applications of these techniques,and show that our approaches are feasible.

Seismic exploration is one of the most important application areas for high performance computing.By tracking the development trends of high performance computers at home and aboard,analyzing the requirements and application status of geophysical exploration to high performance computing,and forecasting the development trends of the high performance computing,the following conclusions and understandings were obtained in this paper:(1):Multi-cores will be the future development trends for high performance computing,(2):High performance computing is needed in pre-stack depth migration,pre-stack inversion and full waveform inversion,and single point high density exploration in seismic exploration,(3):GPU technology has wide application prospects,especially the newly built CUDA framework which improves the software development environment,(4):The Reconfigurable Technology which is based on FPGAs(Field Programmable Gate Arrays)not only has hardware's calculation performance,but also has software flexibility,application of this technology could greatly raise the computing speed,(5):Constrained by power consumption and traditional Integrated Circuit Technology,there is significant limitation for single CPU performance improvements,developing new materials and improving computer's package structure become the new ways for raising computer's performance,there should be good future for some developments,such as Avalanche Photoelectric Diode(APD)Silicon photonic devices,memory+CPU MCP package structure,(6):Cloud Computing is a totally new mode of data-intensive supercomputing mode which is based on distribution computing,parallel computing and grid computing,the technology will have a good application prospect in high performance computing for vast amount of data.(7):The raising of the computing performance depends on integrated development of hardware and software,compared with fast development in hardware,the development and application of software were left behind,as a result greatly developing the software industry is the only way to solve the above problems.

The reference signal delay on the auxiliarychannels often occurs during vibroseis acquisition.We review in this paper the synchronization con-cept between the seismic recording system and thevibrator，and find out that this delay actually iscaused by seismic data recorded earlier than theauxiliary channel data during the acquisition. Weanalyze the delay affects on first arrivals，energyand frequency of a correlated single shot record，and propose some approaches for asynchronousproblem identification and some solutions to them，which may be helpful for field seismologists.

OVT-domain wide-azimuth prestack seismic attribute analysis is one of the most important approaches in wide azimuth seismic. Based on azimuthal anisotropy analysis, it can excavate geological and fluid information contained in prestack seismic datasets and effectively carry out reservoir prediction. In this paper we first make a brief introduction to OVT and its development history, and its innovations on seismic interpretation, and then discuss four types of OVT-domain prestack seismic attribute analysis, namely, the template-based dynamic OVT gather analysis and stacking imaging, OVT-domain multi-offset and multi-azimuth analysis, AVO analysis, and azimuthal anisotropy analysis. As an advanced prestack seismic interpretation tool, it provides an effective way for reservoir and fluid prediction on prestack seismic data. Real examples in carbonate fracture prediction show that the proposed approach breaks through the limitations of conventional poststack seismic interpretation, realize the high-precision azimuthal anisotropy analysis based on OVT gathers, and improve the accuracy of seismic structure analysis and reservoir characterization.

The Gauss function whose window width changes in inverse proportion with frequency was used in generalized S-transform,while for improved generalized S-transform the variable width window was used,the window's width change with frequency was proportional.That is,the window is narrower for low frequency with the high time resolution,while the window is wider for high frequency with the high frequency resolution.With the new method the lossless generalized S-inverse transform can be conducted and time-dependent Q value can be estimated,so the under-compensation and over compensation which developed in traditional Q compensation method were avoided.After compensation,the variation trend of the timefrequency spectrum are exactly the same at every moment,and the seismic frequency bands are the same.Application of the new method in the field VSP data shows that the new method works very well for absorption and attenuation compensation,it also raises resolution and improves data quality.

Nowadays for most vibroseis acquisition in China,common shot-point gather datasets were acquired by cross-correlating vibroseis scanning signal and the received signal by seismic recording system,this process was normally accomplished by hardware in seismic recording system.For the cross-correlation single shot record,the existence of the coherent noise reduces the signal to noise ratio of the first arrival,so the minimum phase processing for the record is needed before picking up the first arrival.By utilizing scanning signal or surface signal to conduct deconvolution processing for the seismic records,the signal to noise ratio of the first arrival can be improved and the first arrival taking-off can be much more clear so that the first arrival picking up accuracy and static accuracy can be raised.In low signal to noise ratio area,the HCI(Human-computer interaction)mode should be adopted,by changing display mode the first arrival taking-off effect can be improved and the accuracy for the first arrival picking up and the static correction can be raised.

For the seismic data with low signal to noise ratio and large residual static correction,the common surface point residual static correction method in which the residual static correction for shot point and receiver were respectively calculated was proposed in this paper.Based on the NMO common shot point gathers and NMO common receiver point gathers,the residual static correction on both receiver and shot points were respectively estimated by cross-correlating each trace in the gathers with the model traces which were the stacking traces of the NMO common shot point gathers or the NMO common receiver point gathers respectively.The testing for the theoretical and field data shows that the method could solve the static correction problem for the seismic data with low signal to noise ratio and the large residual static correction.

In complex areas data processing,residual normal moveout cannot be ignored as residual normal moveout and residual statics impact seismic data imaging.In this work we propose a residual static correction approach based on traveltime decomposition in multiple time windows.First,we convert the residual normal moveout to the velocity error function.Then by decomposing the traveltime in multiple time windows we get statics on shot points and receiver points,as well as velocity errors.We apply velocity errors for residual normal moveout in the corresponding windows.Finally we apply residual static correction on shot points and receiver points.Real data examples show that this method is effective on residual static correction in complex areas.

In order to identify the thin reservoirs,the low amplitude structures,the small faults and the small scale geological bodies in the reservoir development,the high resolution technique which is aiming at protecting and raising the signal to noise ratio for the high frequency component was studied in this paper.With the technique the wavelet can be effectively compressed for post-stack data and pre-stack data,the frequency band can be expanded so the seismic data resolution can be raised.The application of the technique in the seismic data processing in Yongxin Block of Shengli exploration area show that the seismic resolution was raised,weak reflection became clearer,better imaging quality was achieved for the low amplitude structures,richer geological information were seen,and the main frequency of the exploration target was raised from 20～30Hz to 46～50Hz,the technique is very effective for raising the seismic data processing quality and resolving the imaging problem for the low amplitude structures in the terrestrial thin interbed reservoir.

Conventional methods of 3D seismic geometry design are based on the assumption of horizontal subsurface reflectors,which is not suitable for complex structure.Based on the previous research on two-dimensional problem,this paper develops a 3D target-oriented optimal geometry design method using the seismic illumination.This method uses the one-way Fourier finite-difference wave propagator to extrapolate plane wave sources from the target layer to the surface.By analyzing the wave energy distribution at the surface extrapolated from the target layer,the optimal shot positions for the target best illuminated can be determined.And finally,the imaging quality of the target or the shadow areas can be improved.In the numerical tests,seismic illumination and migration results based on the 3D SEG-EAGE salt model suggest that this 3D optimal geometry design method is effective and available.

Migration deconvolution method is effective for raising resolution of the migrated sections,the Green Function which was needed by migration deconvolution method is based on the assumption in which the acquisition geometry and velocity model only vary with the depth,estimation of migration deconvolution filtering factor takes a large amount of time,especially for 3d datasets.In order to solve the problem a fast algorithm of post-stack migration Green Function which is based on homogenous medium assumption was proposed in this paper,its main idea is as below:For post-stack datasets,the source and the receiver are in a same location,meanwhile by regarding the geometry as regular and based on the assumption of migration Green Function's shift invariance we only need to calculate a migration Green Function at each depth level.Through fast migration deconvolution method,the constant velocity scanning was used to design optimized deconvolution operator which fits the circumstance of lateral velocity variation.The preliminary experiments for different datasets show that the fast migration deconvolution operator could effectively raise the calculation efficiency and the imaging quality of the migrated sections.

The surface conditions in the shipping areas of large-scale harbour are complex,conducting 3D acquisition in those areas will face many challenges,such as serious deficiencies for shot points and receiver points,incomplete target data acquired,severe environment noise,weak effective reflection energy for the middle and deep layers and so on.This paper attempts to conduct special geometry design in those areas and the basic idea is as below: According to the design scheme for swath geometry,considering the features of surface and terrain for the harbor,navigation channel,container storage area and bulk logistics,and by using the high accuracy satellite pictures and field survey results,the targeted solutions,such as reasonable splicing for local land and water areas,off-line survey,multi shooting and receiving at the same physical point,increase of spread density and so on,were utilized,and then a set of special geometry design method for harbor areas was summarized.The Application of the method in the geometry design for acquisition of seismic data in BH harbor area proved its better effectiveness.

There are more and more high density and large trace number(3D) seismic exploration application,which brings new challenge for the field seismic acquisition,for example the current SPS software does not support large trace number acquisition.The SPS file preparation method for over ten thousand trace in seismic exploration was discussed in this paper,at first the difference between the conventional SPS file format and the SPS file format for over ten thousand trace was compared,then the problem for using the conventional SPS file format in acquisition for over ten thousand was analyzed,thirdly the SPS file format was analyzed and summarized,and fourthly the development and realization of the SPS file preparation software for over ten thousand trace were introduced,and at last the SPS file preparation software for over ten thousand trace was used in field seismic data processing,great results were achieved with the method.

柴达木盆地三湖地区地震资料受广泛发育的气云的影响,导致纵波在含气构造部位成像质量较差,而转换波勘探技术可望成为解决气云区成像问题的有效手段。本文以柴达木盆地涩北气田为实例,采用伪谱法对该区气云进行数值正演模拟;通过对模型数据的分析研究,可见到明显的二极化现象,该现象是影响转换波成像质量的重要因素;应用将转换波速度分解为基本速度和速度扰动的二极化校正方法,可消除转换波二极化效应的影响,提高转换波成像质量。采用上述方法对该区二维三分量地震数据进行处理,可在转换波数据上观测到明显的二极化现象,二极化校正方法的应用的确能提高气云区转换波成像质量。

Compared with the routine deconvolution,the spectral modeling deconvolution has better adaptivity for non-white noise reflection coefficient,with the method the better results can be obtained in the processing in which the residual wavelet was compressed so the resolution was raised.However the method has following limitations:(1) The polynomial used in fitting limits the shape of the wavelet amplitude spectrum;(2) It does not consider the color characteristics of the reflection coefficient,the expected blue characteristic of the reflection coefficient amplitude spectrum was not seen in the deconvolution results.In order to compensate the defects,a new way to realize spectral modeling deconvolution was proposed in this paper:(1) Do not use polynomial fitting,regarding the amplitude spectrum of the seismic records as a real sequence,a filter was used to smooth the sequence so the wavelet amplitude spectrum could be estimated;(2) Considering the color characteristic of the reflection coefficient sequence,before modeling the wavelet amplitude spectrum,the color influence of the reflection coefficient sequence was compressed.The theoretical experiment and processing results for the field datasets show that the method is simple and easy to realize,with the method the wavelet amplitude spectrum can be accurately estimated,better deconvolution results can be obtained.

Irregular sampling seismic data could cause problems for multi-channel seismic data processing and also could decrease data processing quality.For 3D irregular seismic data with the limited bandwidth inversion reconstruction was conducted by integration of 2D space non-uniform Fourier transform theory and Bayesian parameter inversion method.At first by using frequency division method and based on minimum apparent velocity for every time frequency the spatial frequency bandwidth was determined for the data which will be reconstructed and the spatial Fourier spectrum of the reconstructed data was estimated from the irregular seismic data,then by regarding the irregular seismic reconstruction as geophysical reverse problem,Bayesian parameter inversion theory was utilized to estimate the spatial Fourier spectrum.In the inversion solution,Delaunay triangle grid subdivision scheme was used to determine the weight value of the irregular sample points.In addition in order to avoid complex matrix inversion pre-condition conjugate gradient algorithm was utilized to insure the stability and convergence speed for the solution.The theory model and processing results for the field data proved the effectiveness and practicality of the method.

The on-shore multi-wavemulti-component seismic acquisition technique has become the hotspot of the technical development in geophysical area.Regarding the technical requirements in reservoir geophysics in Daqing Oilfield,several key techniques,such as multi-wavemulti-component seismic acquisition geometry designing,P-waveS-wave joint surface structure investigation,seismic shooting,3C seismic date receiving and so on were studied in detail,based on the studies the digital 3C seismic acquisition technique series in Daqing Oilfield were formed,by application of the technique in XC area,LMD area and other areas in Daqing exploration area,high quality multi-wave 2D and 3D seismic data were acquired.

Using generalized S-transformation this work analyzes low frequency shadow on zero-offset VSP pre-stack data.With VSP geometry that directly receives up-going and down-going waves near target layers,this analysis quality will be improved.We also give low-frequency shadow attribute analysis process and corresponding processing method in the article.The field data examples show that our low frequency shadow detection method can indicate the existence of oil and gas.

Seismic weak signal is a real big challenge for seismic explorations.Based on amplitude characteristics of seismic weak signal in thick and thin layers,this paper analyzes the spectrum characteristics of seismic weak signal as well as the influence of noise on it.In addition,we conduct preliminary discussions about the detection and identification of weak signal using the singular value decomposition(SVD) and curvelet transform.The results indicate that: 1.It is basically impossible to detect weak signal by visual recognition when S/N0.5;2.For thin reservoirs,the tuning thickness could be identified if the S/N is 2;3.The spectrum of the weak signal involved in the adjacent strong reflection cannot show its characteristic;4.Horizontal weak events mixed with noise can be effectively detected by the SVD method while non-horizontal weak events mixed with noise can be detected by curvelet transform.

Vibroseis acquisition can be divided into 3 categories:conventional,high efficiency and high fidelity(HF).In conventional method,only one fleet of vibrators is used and shot gathers are obtained through cross-correlation.In high efficiency acquisition,two or more fleets of vibrators shoot at same time or at constant time interval,and shot gathers are obtained also by cross-correlation.In HF acquisition,one or more fleets vibrate simultaneously at several shot points with constant interval,and shot gathers are obtained through ground force signal deconvolution.Comparing application examples in the field,we conclude that high efficiency acquisition leads high production and the operation cost is obviously reduced,and one of the development trends might be integration of high efficiency and high fidelity(HF) method.

Based on the assumption of the 1D continuous medium model,the non ray-tracing tomography static correction technique implicitly utilizes the propagation law and the dynamic characteristics of the horizontal surface turning wave to conduct tomography inversion for the surface model.The loess layer in the Loess Plateau,Ordos Basin is very thick with server relief surface,however lateral velocity change in the weathered layer is relatively stable and the velocity showed a continuous variation in vertical direction,so it matches the assumption of the 1D continuous medium model.Due to its relief surface,the time-distance curve characteristics of the turning wave for the horizontal surface can not be established,so the non ray-tracing tomography static correction technique can not be directly utilized.In this paper the basic fundamental of the non ray-tracing tomography static correction technique,its algorithm and suitable conditions were firstly discussed,then regarding the relief surface in the Loess Plateau,the time-distance curve equation of the relief surface in the continuous medium was derived,by integration of the micro-logging method,the polynomial fitting for time-depth curve of the shallow refraction data,and the first arrival time-distance curve exponential fitting for the field single shot,the influence of the relief surface to the first arrival propagation time was removed,then by application of the non ray-tracing tomography static correction technique the static correction problem in the Loess Plateau was successfully solved.

Offset uniform distribution is always the goal in geometry designing for seismic acquisition as the offset distribution has severe influence to velocity analysis and stacking imaging precision.Nowadays our main tool to evaluate a geometry designing and to conduct qualitative analysis for the performance of the geometry is the offset distribution attribute map.In this paper by linking the offset distribution and folds/maximum offset,the quantitative analysis formula and the nonuniformity coefficient new concept were introduced,and they are used to describe the offset uniformity status for each bin.By conducting analysis of offset nonuniformity coefficient for 4 kinds of track group recording geometry and orthogonal geometry with different aspect ratios,the most evenly distributed geometry was quantitatively derived,providing the new method and means for geometry designing in seismic acquisition.

We have developed a deformable-layer tomography method with the joint use of first breaks and shallow reflections (Joint DLT) to calculate static corrections. The method is tested with a synthetic model and a field dataset from Tarim Basin,Western China. The synthetic test shows that our joint DLT method can provide velocity interface geometries with high resolution. The field test result indicates that the method can yield a geologically reasonable near-surface velocity model,and an improved stack section in comparison with the sections from the DLT (using only first breaks) as well as two other kinds of commercial tomostatics software.

For the common offset gathers the multi-path issue of the seismic wave propagation in the complicated medium causes inaccurate reflection points.The common reflection angle gathers overcomes the problem above so the complex subsurface structures can be accurately imaged,the common reflection angle gathers can be used in the AVA analysis and amplitude-preserved migration imaging studies,especially for the complicated structure areas with wide reflection angle and multi-wave arrivals,the amplitude and phase of the reflection events were effectively preserved.Based on the common reflection angle migration method,the common reflection angle gather construction,travel time calculation,and estimation of the geometrical dispersion factor,as well as the influence of the migration stretch to the common reflection angle gather datasets were studied.The trial calculation was conducted with the theoretical model data,2D field seismic data were used to validate the method,excellent results were achieved for imaging the steep structures.The studies results show that application of the common reflection angle gathers could better conduct the velocity modeling optimization and the AVA analysis.

Porosity and gas saturation play a significantrole on AVO responses. We use in this paper AVOforward modeling to create the seismic reflectionfor various assemblages of seal and reservoir withvarious porosity and gas saturation. Then we per-form a quantitative analysis of gas saturation bythe variations of AVO intercept and gradient de-rived from Shuey's two-term approximation andCastagna's classification.It is demonstrated thatboth sand porosity and its gas saturation impact onAVO responses:①AVO intercept decreases withporosity increasing，and gradient decreases withgas saturation increasing.②AVO response variesweakly while gas saturation is bigger than 20%.AVO responses of gas bearing sand transits fromclass Ⅱ to class Ⅲ when the acoustic impedance ofseal is lower than the reservoir matrix impedance，and from class Ⅲ to class Ⅳwhen the acoustic im-pedance of seal and the reservoir matrix impedanceare equivalent，class Ⅳ occupies a dominant posi-tion when the acoustic impedance of seal is higherthan the reservoir matrix impedance.

Based on improved algorithm by liu et al.,thking Morlet wavelet as basic matching wavelet,making fully using of the instantaneous characteristics of seismic signal to determine the scanning range dynamically and creating a dynamic wavelet library according to characteristics of seismic signal itself in determination of controlling parameters;and then determning the several matchng wavelet simultaneously through one iteration,using the matching wavelets to control the relationship among the parameters,the dual-parameter fast matching tracing algorithm was proposed in this paper,which further reduced the number of scanning parameters and greatly raised the calculation efficiency.In order to gain faster convergence of the algorithm,the energy of the residual signal was utilized to effectively control the iteration times for the fast matching tracing algorithm,which not only avoid the meaningless calculation,but also could remove random noise. Finaly,by utilizing independence of each matching wavelet,a variable window short-time Fourier transform method was proposed and used,through which the time-frequency distribution map was obtained.

Based on the PROMAX processing system,a seismic data processing technique which was studied in the relevant documents was applied in the wide azimuth seismic data processing for K Block in Kazakhstan,then the excellent processing results were obtained.Based on the wide azimuth seismic data from K Block,the fidelity processing,static correction,apparent anisotropy NMO and sub-azimuth velocity analysis were studied in detail in this paper,the application results show that application of the wide azimuth seismic data processing technique could better detect the distribution of the fractures.

The conventional 3D seismic geometry designing is based on the horizontally stratified medium presumption,its main objective is to obtain regularly sampled stacking dataset,which can be used to image the geological target through post-stack migration.Different from post-stack migration in which the regular post-stack data volume is used,the pre-stack migration uses irregular offset datasets.The irregular spatial sampling of the 3D geometry could probably result in severe migration noise,which then may partially decrease the effect of the pre-stack migration.Designing the 3D geometry which meets the requirement of pre-stack migration has great significance by fully making use of the advantages of the pre-stack migration and raising the imaging accuracy.The new geometry designing method was introduced in this paper,based on the evenly sampling and bin attribute consistence principle the geometry template was designed,good spatial samples were acquired,the designed geometry were gradually optimized by using focus beam,pre-stack migration response,forward modeling,wave field illumination and other techniques,at last the geometry which could meet the requirement of pre-stack migration and could resolve geological problem was obtained.The new method was applied in QK survey in Dongpu Depression and the excellent results were achieved in the survey.

In this paper the forward modeling for theoretical model and field model of the salt dome structure was conducted by using staggered grid high-order finite difference method of the inhomogeneous medium elastic wave equation and acoustic equation,by application of the single-frequency harmonic source and through the elastic wave equation numerical simulation,the divergence field,the vortex field,the kinetic energy field and the potential energy flow field for the elastic wave were acquired,the energy and the propagation characteristics of the elastic wave were quantitatively delineated.Through the wave field snapshot,single shot record and the zero-offset sections,the influence of the complicated salt dome structure to the seismic response were analyzed in detail.The numerical simulation results for the theoretical model and field model show the following conclusions:(1).The elastic wave divergence field and the vortex field respectively described the P-wave wave-field energy characteristics and the converted wave wave-field characteristics,the kinetic energy field and the potential energy flow field then delineated the total field energy characteristics and its propagation characteristics,compared with the acoustic wave equation,the elastic wave numerical simulation could more realistically characterized the total field energy characteristics and its responses,(2).The salt dome caused obvious energy focusing effects for the reflection wave-field and the scattered wave-field,it imposed great modulation on the wavefront of the transmitted wave,the reflection wave-field and the scattered wave-field which were caused by the salt dome,the energy shielding from the high velocity salt dome could form the energy shadow zone,and then the energy shadow zone may affect the deep reflection signal and lowed down the signal to noise ratio.(3).Compared with the Kirchhoff pre-stack time migration,the Kirchhoff pre-stack depth migration could more accurately image for the steep structures beside the salt dome and under the salt dome,however for the scattered wave from the left side and right side within the salt dome,the imaging quality is not great,this is due to the fact that the Kirchhoff integration migration method is based on the ray tracing algorithm,as a result the imaging method for the scattered wave should be developed.

The major oil-fields in Daqing placanticline already came into late super high water-bearing development period.The urban area in Daqing Oil-field are now the major target for development of the residual oil.Regarding a series of difficulties in the major urban area,such as dense production facilities,dense population,wide distribution of interference source,complicated surface structures,hard geological targets and difficult safety environment and so on,the key technique in seismic shooting was designed in seismic acquisition,the studies on borehole shooting,shooting safety distance,selection of shooting charge in the urban area,the special design for the shooting points and the seismic shooting standardized operation were conducted,the relevant techniques which were involved in the 3D seismic shooting were formed,the remarkable geological effects were acquired.

Based on the research results by Lawton et al.,the influence of water depth to bin attribute and seismic data in OBC exploration was discussed in this paper.By applying conventional PATCH geometry,the fold changing for near offset and far offset under both the wide and the narrow geometries were studied,it was founded out in the studies that in order to meet the need of target zone the geometry designing optimization is needed when the survey was acquired in the relatively deep water area,through forward modeling analysis the specialties of seismic data processing in the relatively deep water area were discussed,the wave field continuation method was proposed to conduct the correction in order to relieve the influence of the deep water.

This paper proposes a seismic random noise suppression method using the predictive filter in the discrete cosine transform(DCT) domain,and then evaluates its performance.In comparison with the discrete Fourier transform(DFT),DCT can represent seismic signals with fewer coefficients,i.e.,DCT has superior energy compaction for seismic signal.That is why DCT can separate seismic signals from random noise better.The results from both synthetic and real data show that the proposed method achieves better performance for random noise suppression and signal preservation compared with the f-x prediction filter.

Regarding the carbonate reservoir in Tazhong Area,wave equation forward modeling were conducted and the finite difference algorithm was used to solve the wave equation in order to disclose the formation mechanism of vertical "long string beads".The study results show that the diffraction wave could be formed by single and big cave,vertical overlap cave,sliding fault and the formation composition,conducting migration imaging for the diffraction wave could form vertical "long string beads" reflection.For the double string bead formed by single cave,the different reflection coefficients between the top layer and bottom layer lead to a top string bead waveform,like two troughs and one peak,and a bottom string bead waveform,like two peaks and one trough.The double string bead formed by double caves is the two string beads with same reflection characteristics,it is easy to distinguish,the combination of strata and the sliding fault could result in the formation of several vertical string beads,the pre-assumption is that there should be obvious inner layers for the carbonate rocks,and the erosion should exist along the sliding fault.Those conclusions could be referred when studying formation mechanism of the complicated seismic response,understanding the geological mode and guiding the exploration and development.

Off-line 3D seismic acquisition,developed on off-line 2D seismic,has advantages of suppressing noise.This paper discusses an off-line 3D seismic acquisition in Jiyuan loess area,Erdos Basin.Source parameters are optimized based on near surface investigation by uphole.Geological target oriented off-line 3D geometry is designed and testified.High quality 3D data cube obtained by our off-line 3D seismic acquisition shows not only its effectivity,but also oil exploration prospect in this area.