英文摘要

Seismicdatadescription：velocityoracceleration.WEIJidong1.OilGeophysicalProspecting，2019,54(2)：243-253.

In the land seismic survey，mechanical vibration of the ground are recorded as seismic data.Normally this data is described in velocity or acceleration，two are common forms used for onshore petroleum exploration.We discuss in the paper the meaningful frequency band and amplitude range of onshore seismic survey in velo-city and acceleration，and analyze various factors involved in the seismic recording system(sensor，sensor-ground coupling，and seismograph).In land seismic survey，commonly used sensors are geophones，among which the model 20DX geophone is very popular.Another one is MEMS,an acceleration sensor,Sercel’s DSUs for instance.We review velocity and acceleration of typical sensors，compare their consistency of data，and analyze recorded data reasonability and validity with physical and numeric results.Finally more geolo-gical and geophysical factors should be taken into accounts carefully when selecting the description domain of seismic data.

Keywords：seismic data description，physical quantity，velocity，acceleration

1.Shengli Branch，Geophysical Company，SINOPEC，Dongying，Shandong 257100，China

Amethodoffastdetectingshotpointdeviationbasedonthenearestoffsettrace.WEIXinjian1,YANGWuyang1,WANGWanli1,LIDong1,CHENDewu1,andLIShuping1.OilGeophysicalProspecting，2019,54(2)：254-260.

During the seismic acquisition，it is easy to lead to the shotpoint deviation due to rough terrain，staff negligence，and other reasons，which has an adverse impact on the accuracy of normal moveout corrections and stacking data，even causes continuously bad shot records.Based on the property of the nearest-offset trace(shortest first break time and highest energy)，we propose a method for fast detection and correction of shotpoint deviation.In order to improve the efficiency and accuracy，only the seismic information of the nearest-offset trace is used.First，the nearest-offset trace is determined by the theory first break time and the real first break time，and the highest-energy trace is found.If they are the same trace，the shotpoint is normal，otherwise，the shotpoint is deviated.Finally the shotpoint deviation is automatically corrected with the calculated deviation.Field applications show that the proposed method can quickly detect shotpoint deviation and automatically correct it，which fully meets the requirement of real-time QC during the high-productivity seismic acquisition.

Keywords：shotpoint deviation，theoretical first arrival model，nearest-offset trace，multi-window energy ratio，batch first break editing

1.Northwest Branch，Research Institute of Petroleum Exploration & Development，PetroChina，Lanzhou，Gansu 730020，China

Fastnear-surfacemodelbuildingwithturningwave.GUOZhenbo1,SUNPengyuan1,QIANZhongping1,LIPeiming1,TANGBowen1,andXIONGDingyu1.OilGeophysicalProspecting，2019,54(2)：261-267.

Conventional first-arrival travel time tomography based on iterative inversion is computationally intensive and time consuming，especially in a large-scale data processing.In order to improve the efficiency of near-surface modeling，a fast near-surface model building with turning wave is developed by assuming that the near-surface velocity is transversely constant within the maximum offset range and varies linearly with the depth.In order to improve the accuracy of inversion，a multi-datum correction method is adopted to reduce the influence of surface undulation on the inversion results.In order to enhance the stability of inversion，a local weighted ray parameter estimation is developed to increase the robustness with respect to noise.Synthetic and real data tests verify the validity and efficiency of the proposed method.

Keywords：near-surface，tomography，velocity model building，inversion，statics，turning wave

1.Research & Development Center，BGP inc.，CNPC，Zhuozhou，Hebei 072751，China

High-productivityblendedacquireddataseparationbysparseinversion.SONGJiawen1,LIPeiming1,WANGWenchuang1,WANGChengxiang1,LIHequn1,andWANGBaobin1.OilGeophysicalProspecting，2019,54(2)：268-273.

The vibroseis blending acquisition improves greatly acquisition efficiency.However，this acquisition brings serious noise in massive blended seismic data due to the continuous shooting.Therefore accurate，stable，and fast noise-separation algorithms are needed.We propose in this paper an inversion-based de-blending method applied on 3D common receiver gathers.Firstly，temporal-spatial seismic data is transformed into the frequency-wavenumber-wavenumber(FKK) domain data by 3D fast Fourier transform.Then，the hard thresholding algorithm extracts coherent signals，and noise is predicted with the extracted coherent signals.Finally，driven by data residuals，signals are iteratively updated with shrinking thresholds until full noise separation from data is achieved.Tests on both synthetic and field data show that the proposed method can separate high-productivity blended acquired data in an accurate，stable and fast way.

Keywords：high-productivity blending acquisition，signal and noise separation，3D common receiver gather，frequency-wavenumber-wavenumber(FKK) domain，sparse inversion

1.Research & Development Center，BGP Inc.，CNPC，Zhuozhou，Hebei 072750，China

First-breakresidualstaticcorrectionsappliedinthesouthernpartofAnjihaiarea.PANLong1,LIUYiwen1,ZHENGHongming1,ZHAOYong1,andGUOQi1.OilGeophysicalProspecting，2019,54(2)：274-279.

In the southern of Anjiha，mountain front of Junggar Basin southern margin，it is usually very difficult to solve serious field statics problem with conventional datum correction methods due to complex near-surface structures.As a result，residual static corrections cannot be well achieved due to seismic data low signal-to-noise ratio(SNR).To solve the problem we propose first-break residual statics method，which uses statistics of high-SNR data first breaks to calculate residual statics of shotpoints or receivers.This method does not depend on surface models，and has not the limit of statics.We discuss also in the paper favorable conditions for application of 2 residual static corrections：model-curve method and difference method.They achieve good results in the southern of Anjihai area.

Keywords：static corrections，first break，residual static corrections，difference method，model

1.Geophysical Department，Research Institute of Exploration and Development，Xinjiang Oilfield Company,PetroChina，Urumqi，Xinjiang 830013，China

Alocalorthogonalizationforseismicrandomnoisesuppression.XUYankai1,2，CAOSiyuan1,2，PANXiao1，3，YANGGuangming4，andZHANGXianxu4.OilGeophysicalProspecting，2019,54(2)：280-287.

The noise section remains a certain amount of useful signal after random noise attenuation.Therefore，we propose in this paper a new approach to retrieve useful signal from the initial noise section based on local signal-and-noise orthogonalization.We firstly use a conventional method to finish initial signal noise separation.The adaptive singular value decomposition(ASVD) is adopted for obtaining higher signal-to-noise ratio(SNR) on the initially de-noised section.Then we predict and retrieve useful signals from the initial noise via a weighting operator.The weighting operator is optimized by solving a least-squares minimization problem via shaping regularization with a smoothness constraint.The final de-noised section is composed of the retrieved signal and the initially de-noised section.Synthetic and field data examples show that the proposed approach can further retrieve useful signal from the initial noise section and effectively attenuate noise and improve seismic data SNR compared with thef-xfiltering and the singular value decomposition.

Keywords：random noise，local orthogonalization，signal-to-noise ratio，shaping regularization，adaptive singular value decomposition(ASVD)

1.College of Geophysics and Information Engineering，China University of Petroleum(Beijing)，Beijing 102249，China

2.CNPC Key Laboratory of Geophysical Exploration,China University of Petroleum(Beijing)，Beijing 102249，China

3.Department of Earth and Space Sciences，Southern University of Science and Technology，Shenzhen，Guangdong 518055，China

4.Xi’an Research Institute，China Coal Technology & Engineering Group，Xi’an，Shaanxi 710077，China

Rayleighwavedispersioninversionbasedongrasshopperoptimizationalgorithm.YUDongkai1，SONGXianhai1,2，ZHANGXueqiang1,ZHAOSutao1,andCAIWei1.OilGeophysicalProspecting，2019,54(2)：288-301.

As a new algorithm，the grasshopper optimization algorithm(GOA) belongs to swarm intelligent algorithms.It is inspired by the unique foraging behavior of grasshoppers at different stages.The movement of any grasshopper will be impacted by all the other grasshopper,which ensure the accuracy of convergence.In this paper，GOA is applied to invert surface-wave phase velocities.Using synthetic and real Rayleigh wave data，we examine the effectiveness and applicability of the GOA scheme in deducing an S-wave velocity profile for near-surface applications.The objective function in the proposed algorithm is proved to be able to rapidly converge to the global optimization solution.Another advantage of the proposed algorithm is a wide probability distribution of model parameters，which means this algorithm can define the scope of true-value and find the global minimum even in an extensive search space to guarantee the reliability of inversion results.

Keywords：grasshopper optimization algorithm(GOA)，swarm intelligence，Rayleigh wave，dispersion curve，nonlinear inversion

1.Institute of Geophysics & Geomatics，China University of Geosciences(Wuhan)，Wuhan，Hubei 430074，China

2.Hubei Subsurface Multi-scale Imaging Laboratory(SMIL)，China University of Geosciences(Wuhan)，Wuhan，Hubei 430074，China

qP-wavenumericalsimulationinTTImediawithpseudo-spectralmethod.ZHANGQingchao1,ZHUGuowei1,ZHOUJunjie1,ZHUCongcong1,andLIUWeigang1.OilGeophysicalProspecting，2019,54(2)：302-311.

Based on Tsvankin’s exact phase velocity for VTI media，we obtain the exact phase velocity of qP-wave for 3D TTI media with the coordinate transformation.Then following Thomsen anisotropic parameters，we gain the approximate formula of phase velocity for 3D TTI media with Taylor series.The phase velocity analysis shows that the approximate formula could well fit the exact formula.From the approximate formula of phase velocity，we derive the qP-wave dispersion relation and wave equation in the time-wavenumber domain for 3D TTI media.The stability of the wave equation is analyzed.Numerical examples demonstrate that the solution of the wave equation proposed in this paper is stable and free of S-wave artifacts.

Keywords：TTI media，phase velocity，pure qP-wave，finite difference method，pseudo-spectral method

1.State Key Laboratory of Coal Resources and Safe Mining，China University of Mining and Technology(Beijing)，Beijing 100083，China

Originanalysisofthelarge-scaleshallowgas-obscuredzone：anexampleoftheOilfieldA，BohaiBay.MINGJun1,ZOUZhen2，XIATongxing1,CAOSheng2，andLIULei1.OilGeophysicalProspecting，2019,54(2)：312-319.

A large-scale gas cloud zone in the Oilfield A，Bo-

hai Bay causes poor quality of P wave data，so subsurface structures are very difficult to be depicted.Based on multi-discipline information including surface seismic，VSP，and geologic data，we build a number of 2D and 3D models and achieve the forward modeling based on acoustic equation and synthetic data evaluation.According to our research，the seismic wave scattering caused by shallow large-scale heterogeneous stratum(shallow gas zone) is an important reason for blurring seismic imaging of gas cloud zone.The sag structure perpendicular to the long axis direction of shallow gas further aggravates the imaging difficulty on existing 3D seismic data(acquisition along the long axis direction of shallow gas zone).Real data processing shows that the near-surface velocity provided by turning-ray tomography，and wave equation prestack depth migration(PSDM) with multi-wave arrivals can improve the imaging quality of P-wave in the gas cloud zone.

Keywords：gas cloud zone，scatters，simulation，turning-wave tomography，wave-equation prestack depth migration(PSDM)

1.Bohai Oilfield Research Institute，Tianjin Branch，CNOOC，Tianjin 300452，China

2.Geological Research Center，GRI，BGP Inc.，CNPC，Zhuozhou，Hebei 072751，China

SeismicforwardmodelingforcorrectionoffaultshadowzonesinChangyuanOilfield，Daqing.JIANGYan1,CHENGShunguo1,WANGYuanbo1,andLICao1.OilGeophysicalProspecting，2019,54(2)：320-329.

The footwall of large faults in Changyuan Oilfield，Daqing shows a triangular fault shadow zone on seismic sections.Seismic events of the shadow zones are often pulled up，pulled down，or uncontinuous，which lead to a great structural interpretation uncertainty.In order to quantitatively analyze characteristics of the fault shadow zone，a series of 2D forward models are built based on the geological information of the study area.According to our research，the fault shadow zones are caused by lateral velocity changes on both sides of faults，and fault throws and low velocity zones are the main influence factors of the fault shadow zone.The 3D space-variant velocity field is proposed to correct the fault shadow in dense well patterns，which improves effectively structural interpretation nearby the large fault and provides technical support for the future development of Changyuan Oilfield.

Keywords：fault shadow zone，fault throw，low velocity zone，Changyuan Oilfield，dense well pattern

1.Research Institute of Exploration and Development，Daqing Oilfield Company，PetroChina，Daqing，Heilong-jiang 163712，China

Angle-domainprestackdepthmigrationinVTImedia.LIJiang1andLIQingchun2.OilGeophysicalProspecting，2019,54(2)：330-340.

The angle domain migration in VTI media is discussed in this paper.Based on the angle domain migration of isotropic double-square-root equation，a wavefield extension operator of angle domain migration in VTI media is derived from the qP wave dispersion equation.The complex velocity and anisotropic parameter field are divided into two parts，one is lateral uniform background field，and the other is the disturbances of velocity and anisotropic parameters.Then the wave propagated at a uniform velocity and anisotropy field is processed in the frequency wavenumber domain，and the wave propagated at a velocity and anisotropy disturbance field is corrected by time-shift in the spatial domain.So the accuracy of wave field extension is greatly improved.Based on our model and real data tests，the following observation are obtained：A.Because the isotropic migration method does not take into account the influence of anisotropy parameters，the diffraction wave cannot be completely converged and the wavefield is misfocused，which causes low resolution and low signal-to-noise ratio.So conventional migration methods cannot accurately image geological structures，while the VTI media migration can accurately image faults，salt mounds，and small scale geological bodies; B.For the angle domain common imaging gathers(ADCIGs) generated by the prestack migration，the event of the isotropic method cannot be equalized，the residual fault diffraction is wound and the wavefield cannot be properly focused，which cannot correctly reflect local geological characteristics，while the ADCIGs from VTI media migration are relatively straight，the angle range is wider，the wavefield is accurately positioned.So the image accuracy is higher.Therefore，the angle domain migration in VTI media can be suitable for complex-structure accurate imaging.

Keywords：VTI media，angle domain migration，double square-root equation，dispersion equation，wavefield continuation

1.Xi’an Research Institute Co.Ltd.，China Coal Technical & Engineering Group，Xi’an，Shaanxi 710077，China

2.School of Geological Engineering and Geomatics，Chang’an University，Xi’an，Shaanxi 710054，China

ReversetimemigrationinVTImediabasedonADCIGs.QINNing1.OilGeophysicalProspecting，2019,54(2)：341-347.

Conventional isotropic reverse time migration(RTM) method can lead to inaccurate imaging and unfocused seismic event energy when dealing with the anisotropic problem，and the strong amplitude and low frequency noise in the RTM imaging results cannot be completely removed by simple filtering methods such as Laplace filter operator.In order to solve these problems，we apply acoustic approximate equation to simulate the wavefield propagation of qP wave in VTI medium，eliminate the influence of qSV wave through setting smooth isotropic or elliptic anisotropic source ring at source locations.On this basis，the angle domain common imaging gathers(ADCIGs) superposition implementation strategies of RTM in VTI medium has been developed，which use the superposition of imaging results with different angles in ADCIGs to suppress the low-frequency noise and improve the imaging precision.Model tests and real dataset examples verify that the proposed approach can obtain the accurate imaging in complex steep structures with better energy balance and lower low-frequency noise.

Keywords：anisotropy，VTI medium，reverse time migration(RTM)，angle superposition，Poynting vector

1.Geophysical Research Institute，Shengli Oilfield Branch Co.，SINOPEC，Dongying，Shandong 257022，China

Wavelet-independentelasticwavefullwaveforminversioninhybriddomain.YANGTao1,2,3，ZHANGHuixing1,2,3，andSHICaiwang1,2,3.OilGeophysicalProspecting，2019,54(2)：348-355.

The accuracy of seismic wavelet can directly affect the modeling effect of full waveform inversion.In practice，it is very difficult to get the exact wavelet.In view of this problem，we develop a strategy of elastic wave full waveform inversion in hybrid domain based on the convolution for wavelet-influence removal.Based on the second-order elastic wave stress-displacement equation，we carry out a theoretical calculation of full waveform inversion.The objective function of the full waveform inversion of the elastic wave in hybrid domain is obtained by the multiplication of seismic records with characteristic traces of simulated records and the multiplication of simulated records with characteristic traces of seismic records.The theoretical formula of the reverse source is derived.Finally，numerical calculations on the Overthrust model obtain good inversion results，which verify the feasibility of the proposed approach in hybrid domain.

Keywords：full waveform inversion，elastic wave equation，hybrid domain，wavelet，convolution

1.Ocean University of China，Qingdao，Shandong 266100，China

2.Laboratory of Marine Mineral Resource Evaluation and Detection，Qingdao National Laboratory for Marine Science and Technology，Qingdao，Shandong 266071，China

3.Key Laboratory of Submarine Geosciences and Prospecting Techniques，Ministry of Education，Qingdao，Shandong 266100，China

Highgas-saturationreservoirpredictionbasedonfrequency-dependentAVOinversion.LUOXin1,CHENXuehua1,2，ZHANGJie1,JIANGWei1,SUNLeiming3，andXIAOWei3.OilGeophysicalProspecting，2019,54(2)：356-364.

Elastic parameters obtained by conventional pre- or post-stack inversions are not sensitive to gas saturation of reservoirs.Therefore，we use dispersion parameters obtained by frequency-dependent AVO inversion to predict high gas-saturation reservoirs.First the influence of sand-reservoir saturation on viscosity of different fluid mixtures is analyzed with Refutas equation; and the influence of gas-saturation on velocity dispersion and attenuation is analyzed with the dynamic equivalent-medium theory and Wood’s formula.Then the frequency-dependent AVO inversion is achieved based onf-μ-ρAVO approximation; and the sensitive dispersion factor is optimized.The following phenomena are obtained in results：①Different fluids have different dispersion and attenuation，and dispersion and attenuation are dependent on water or gas saturation; ②The optimized dispersion factor is more sensitive to high gas-saturation reservoirs and less affected by the background，which can accurately depict the spatial distribution of high gas-saturation reservoirs.

Keywords：frequency-dependent AVO，dispersion，attenuation，gas saturation，reservoir prediction

1.Key Laboratory of Earth Exploration and Information Techniques，Ministry of Education，Chengdu University of Technology，Chengdu，Sichuan 610059，China

2.State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation，Chengdu University of Technology，Chengdu，Sichuan 610059，China

3.Data Processing Company，Geophysical Branch，China Oilfield Services Limited，CNOOC，Zhanjiang，Guangdong 524057，China

Anisotropicdiffusionedge-preservedfilterbasedonimageentropyandapplicationinfaultidentification.LIJun1,ZHANGJunhua1,LIUYang1,YANGYong2，andDUYushan2.OilGeophysicalProspecting，2019,54(2)：365-370.

Protecting the edge information of geological bodies such as faults is a key of seismic data denoising.In this paper，an anisotropic diffusion edge-preserved filter based on the image entropy method is proposed.Since the entropy information is only related to the overall structure of the data，it can be used to accurately determine special edges of geological bodies including faults.It can quantitatively give the proportion of the second derivative that needs to be added in constructing the structure tensor matrix to judge the diffusion direction more rationally.Model and real data applications show that the proposed method improves the signal-noise ratio and protects small scale edge information of faults，which provides a good foundation for subsequent fault identification on seismic data.

Keywords：edge-preserved denoising，anisotropic diffusion，structure tensor，entropy，continuity factor

1.School of Geosciences，China University of Petroleum(East China)，Qingdao，Shandong 266580，China

2.Research Institute of Exploration & Production，Shengli Oilfield Branch Co.，SINOPEC，Dongying，Shandong 257015，China

First-orderperturbationapproximationofPPwavereflectioncoefficientforHTImediumbasedonazimuthalgeometry.SHANJunzhen1,WUGuochen1,2，andGONGChengcheng1.OilGeophysicalProspecting，2019,54(2)：371-379.

Five-dimensional prestack seismic data contains abundant offset and azimuth information.Newly developed prestack seismic attribute analysis in the offset vector tile(OVT) domain based on five-dimensional seismic data is an effective way to predict reservoirs.In this paper，with the combination of perturbation theory and media decomposition theory，a new first-order perturbation approximation equation of PP wave reflection coefficient for HTI medium based on azimuthal geometry is deduced.The conventional HTI medium reflection coefficient approximation equation is only effective in near offsets，but this newly-deduced equation can better use offset information in five-dimensional seismic data.Calculation results show that the first-order perturbation approximation equation has better accuracy than the conventional linear approximation equation，and AVO characteristics obtained with this approximation are similar with that obtained with the accurate equation，which provides a theoretical basis for five-dimensional seismic inversion with middle and far offset information.

Keywords：five-dimensional seismic data，first-order perturbation，reflection coefficient，azimuthal geometry，amplitude versus offset(AVO)

1.School of Geosciences，China University of Petroleum(East China)，Qingdao，Shandong 266580，China

2.Laboratory for Marine Mineral Resource Evaluation and Detection，Qingdao National Laboratory for Marine Science and Technology，Qingdao，Shandong 266580，China

Remainingoilpredictionbasedontime-lapseseismicdatainLayer1#，ZetaOilfield.LUHongmei1,CHENWenxue1,XUHai1,LUWenming1,andCHENJihua1.OilGeophysicalProspecting，2019,54(2)：380-389,403.

Zeta Oilfield in the deep sea of West Africa has been developed for more than 10 years，and water displacement has been adopted for oil production for some time.However remaining-oil enrichment zones cannot be determined due to unclear directions of water flooding in injection-production well patterns and uneven displacement for different layers.To solve the problem，we carry out a research on the main oil bed，Layer 1#，and predict remaining-oil enrichment zones based on time-lapse seismic data.The adjacent-trace correlation coefficient on the time-lapse seismic data is optimized as a sensitive attribute for remaining oil prediction.Both the dynamic change of water flooding displacement and the water flooding frontier are clearly delineated on time-lapse seismic data.With the integration of geological structures，sand-body distribution，and adjacent-trace correlation coefficient，remaining oil enrichment zones are successfully predicted.And the following understandings are obtained：A.The impedance of oil- or water-content unconsolidated sand reservoirs is smaller than that of overlying deep-sea mudstone; B.The differences of time-lapse seismic data can basically indicate the range and direction of oil-water displacement，in which the correlation coefficient is more sensitive than others，it can better describe the edge position of oil-water displacement in the period of monitor survey acquisition; C.Based on the comprehensive analysis of oilfield structures，sand-body distribution，and correlation coefficient，three remaining oil zones of Layer 1#in 2013 are predicted，among which Zone Ⅲ and the southern part to Well Ⅰ-2 in Zone Ⅱ might be residual oil permanent retention zones.They need to be confirmed by further drilling.

Keywords：time-lapse seismic，liquid displacement，remaining oil，correlation coefficient，injection-production linkage relationship，Zeta Oilfield

1.Research Institute of Petroleum Exploration & Production，SINOPEC，Beijing 100083，China

Cross-wellsand-bodyidentificationintheoilfielddevelopmentlatestage.XULiheng1,MAYaojun2,3，ZHUSuihui3，4，WANGZengcun5，LIZhengxi5，andLIANGYu1.OilGeophysicalProspecting，2019,54(2)：390-397.

After more than 50 years of the exploration and development，Daqing Changyuan Oilfield is now in the stage of dense well pattern and single-bed production.The development geological task is to identify the connectivity of sand bodies and the narrow channel boundary between wells.Based on high-density 3D seismic data and well development information，a sand body prediction model for typical Changyuan Block is established with integrated well-seismic data inversion.Single-channel boundary of composite sands and narrow channel sandbodies between wells are identified by the geologic statistics inversion.It is concluded that the integrated well-seismic data inversion synthesizes the advantages of vertical and lateral high density information，and it is suitable for cross-well sand body identification in the oilfield development late stage.

Keywords：seismic inversion，dense well pattern，integrated well-seismic data inversion，cross-well sand body，oilfield development late stage

1.Research Institute of Exploration and Development，Daqing Oilfield Company，PetroChina，Daqing，Heilongjiang 163712，China

2.Oil Production Plant 5,Qinghai Oilfield Company，PetroChina，Delingha，Qinghai 816400，China

3.School of Geosciences and Technology，Southwest Petroleum University，Chengdu，Sichuan 610500，China

4.Northwest Sichuan Gas Field，Southwest Oil and Gas Field Company，PetroChina，Mianyang，Sichuan 621700，China

5.Laojunmiao Production Plant，Yumen Oilfield Company，PetroChina，Jiuquan，Gansu 735019，China

Seismicresponsecharacteristicsandidentificationoffault-karstreservoirinShunbeiarea，TarimBasin.MANaibai1,JINShenglin2，YANGRuizhao2，MENGLingbin2，WANGLi2，andHUYongzhen2.OilGeophysicalProspecting，2019,54(2)：398-403.

The fault-karst reservoir is a kind of the Ordovician carbonate reservoirs in the Tarim Basin，which is also one of the important targets for the hydrocarbon exploration and development.According to the formation mechanism of fault-karst reservoir combined with real petrophysical parameters，a seismic model of fault-karst reservoir is built，and seismic reflection characteristics of fault-karst reservoir are obtained with seismic forward modeling.The seismic modeling results show that the fault-karst reservoir is centered on large-scale strike-slip faults，forming a bouquet-like seismic reflection.The large-scale strike-slip faults show faulted-fracture on seismic events.Fault-karst fracture-cavity reservoirs show single bead-like reflection，strong or weak bead-like reflection groups.The seismic modeling results agree well with seismic data，which proves that the built fault-karst reservoir model is reliable and can help the identification of fault-karst reservoirs on seismic sections.

Keywords：Shunbei area，fault-karst reservoir，forward modeling，large-scale strike-slip fault，bead-like reflection

1.Research Institute of Exploration and Production，Northwest Oilfield Branch Co.，SINOPEC，Urumqi，Xinjiang 830011，China

2.School of Geosciences and Survey Engineering，China

University of Mining and Technology(Beijing)，Beijing 100083，China

NewunderstandingsofthebasementcharacteristicsandevolutionprocessofErlianBasin.ZHANGYiming1,LIUZhen2，F(xiàn)USheng2，JIANGShuanqi1,YAONing2，andWANGXin1.OilGeophysicalProspecting，2019,54(2)：404-416.

Formers thought Erlian Basin was a Mesozoic-Cenozoic basin developed on a fold basement by wide docking and soft collision during Hercynian period.But they did not specify whether Mengnan Area(namely，Ondor Sum Uplift) belongs to Erlian Basin and only regard it as uplift orogenic belt located in south of the Erlian Basin without analyzing their relationships through basement characteristics and tectonic evolutions.Based on geological and geophysical data，a research of the basement evolution process and tectonic evolution of Erlian Basin is carried out with gravity-magnetic-electric features and sequence stratigraphic cycle correlations.The following understandings are obtained：①The basement evolution of the Erlian Basin experienced six stages including oceanic basin development in Caledonian Period(Stage Ⅰ)，Mengnan area uplifted during Hercynian Period(Stage Ⅱ)，Paleo-Asian ocean-Xing-Meng trough initially developed to finally closed during Hercynian Period(Stage Ⅲ)，unified basement formed during early Indosinian Period(Stage Ⅳ)，unified basin development during late Indosinian to Yanshanian Period(Stage Ⅴ)，and open inland basin development during Himalayan Period(Stage Ⅵ); among which，Ⅱ，Ⅴ，and Ⅵ are key stages; ②The basement of Erlian Basin is characterized by transitional feature，and its north，middle，and south parts were developed respectively in Early Hercynian，Late Hercynian to Indosinian，and Caledonian with distinct features; ③The basement evolution of the Erlian Basin was characterized by unified basement and unified basin，Mengnan area experienced two uplifting periods including Devonian-Permian(Hercynian) and Cenozoic(Himalayan)，and formed unified basin during Late Triassic-Cretaceous(Late Indosinian to Yanshanian) on the unified basement uplift; ④The basement characteristics and basin evolution process of Mengnan area and Erlian Basin are similar，which indicates that Mengnan area is a part of Erlian Basin during geological historical period.

Keywords：Erlian Basin，Mengnan area，basement characteristics，tectonic evolution，gravity-magnetic features，sequence stratigraphic cycle

1.Huabei Oilfield Company，PetroChina，Renqiu，Hebei 062552，China

2.College of Geosciences，China University of Petroleum(Beijing)，Beijing 102249，China

TectoniccharacteristicsanditshydrocarboncontrolintheBlockA，IndusBasin.YANGJianfang1,JIAXue-cheng1,WEIXiaodong1,TANGZichang1,ZHANGDawei1,andLIUCaiqin1.OilGeophysicalProspecting，2019,54(2)：417-422.

Indus Basin is the biggest sedimentary basin in Pa-

kistan，hydrocarbon enrichment zones are mainly in structural traps controlled by faults in Cretaceous.It has a great significance for the hydrocarbon exploration to clarify its tectonic characteristics and evolution.Based on regional tectonic background and abundant seismic data，we analyze structural characteristics and tectonic evaluation，and summarize its control of hydrocarbon accumulations in the Block A of the basin.Based on the tectonic evolution analysis，the study area has undergone three major stages：Gondwanaland continental rift period，Indian plate drift period，and plate collision period.The strike-slip phase of the Indian plate drift period was the main period for trap forming.The tectonic activity after the hydrocarbon accumulation were whole uplift and subsidence，upthrow synthetic fault terrace reservoirs had partially destroyed，while the tectonic activity had very little influence on upthrow antithetic fault terrace reservoirs.As a result，the former hydrocarbon reservoirs are characterized by large closure with small height of hydrocarbon，while the latter hydrocarbon reservoirs are characterized by high filling degree of hydrocarbon.The above observations might provide a guidance of favorable target evaluation in the Block A.

Keywords：Indus Basin，fault pattern，tectonic evolution，structural trap，hydrocarbon accumulation

1.GRI，BGP Inc.，CNPC，Zhuozhou，Hebei 072751，China

Internalstructuresandgeneticmechanismofslumpturbiditefans：anexampleoftheE2l1inWeixinanSag.TAOQianqian1,ZHOUJiaxiong1,SUNWenzhao1,CHENLijun1,andLIDa1.OilGeophysicalProspecting，2019,54(2)：423-432.

Large-scale slump turbidite fans were developed in the upper E2l1of Weixinan Sag，which are favorable targets for the hydrocarbon exploration.A variety of geological and geophysical means such as sedimentary sequence，stratal slice，facies-constrained reservoir prediction，and forward modeling are used to research their internal structures，key controlling factors，and the sedimentary model.The results show that the slump turbidite fan of the upper E2l1in Weixinan Sag has a few incised channels.They show V- or U-shaped wave or short wave with a spot and strip distribution on seismic profile.The lithologic assemblage is characterized by fining-upward sedimentary sequence.The cores have turbidite structures such as deformation bedding，coiling bedding，and impression.Internal structures of turbidite fan in this area are composed of sand bodies with different thickness，different lateral distribution，and variable contact styles.The internal structures and genesis of the turbidite fans were controlled by middle-deep lake facies，its own gravity，and structural slope-break zone of Fault Zone No.2.This study provides references of the slump turbidite fan study for Weixinan Sag and other basins.

Keywords：Weixinan Sag，slump turbidite fan，stratal slice，forward modeling，facies-constrained sparse pulse inversion，internal structure

1.Research Institute，Zhanjiang Branch，CNOOC，Zhanjiang，Guangdong 524057，China

SeismicidentificationoffaultaccommodationzonesinDongxinarea.LUZhiyong1,YANGShaochun1,2,BAIQinglin1,ZHANGShanwen3,YANGKan4,andJINGYayun1.OilGeophysicalProspecting,2019,54(2):433-446,460.

Located in the eastern part of the central uplift belt,Dongxin area in Dongying Sag,10 accommodation zones of subtle faults are identified and classified into 5 types.Structural characteristics of different types of fault accommodation zones and the relationship with the hydrocarbon distribution are detailedly analyzed,and seismic identification marks of different types are constructed.Collateral fault accommodation zones mainly developed in Xinzhen structure are paralleled major faults with step-fault patterns or multiple graben patterns on sections.Overlapping accommodation zones mainly developed in Dongying structure are obliqued with major faults in en echelon arrangement in the plane and their structural style is presented in horsetail patterns and flower structure on sections.Approaching accommodation zones formed by one major fault of Dongying structural belt adjoining other 3 major faults of Xinzhen structural belt are fan-like in plane.On sections,their structural style is presented the patterns of compound flower structure.The accommodation zones controlled by single major fault are divided into the types of inward convergence to hinge zone and divergency in pitching end.The inward convergent accommodation zones developed in northwest part of Dong-ying structure are distributed in the manner of brush convergent to major faults with the patterns of pectination on sections.Whereas,fault accommodation zones of divergency in pitching end developed in the west of Xinzhen structure are distributed in the manner of phoenix tail in plane.On sections,the lower structural style is presented in the patterns of pectination and the upper structural style is presented in pattern of cabbage liking.Collateral accommodation zones and inward convergent accommodation zones can be easily identified with coherence attribute and seismic sections.Then overlapping accommodation zones and approaching accommodation zones can also be identified.The most difficult to be identified is the fault accommodation zones of divergency.The collateral accommodation zones and overlapping zones are the most prolific hydrocarbon areas in Dongxin Fault Zone because their development and activity had a very close relationship with oil source fault activity.The conclusions are instructive and meaningful to fault accommodation zone identification and favorable target optimization in the transtensional fault system.

Keywords: Dongxin area,fault accommodation zone,seismic identification,Dongying Sag,structural characteristics,coupling relationship

1.School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China

2.Laboratory for Marine Mineral Resource Evaluation and Detection,Qingdao National Laboratory for Marine Science and Technology,Qingdao,Shandong 266071,China

3.Shengli Oilfield Branch Co.,SINOPEC,Dongying,Shandong 257001,China

4.Dongxin Oil Production Plant,Shengli Oilfield Branch Co.,SINOPEC,Dongying,Shandong 257001,China

XGBoostalgorithmappliedintheinterpretationoftight-sandgasreservoironwellloggingdata.YANXingyu1,GUHanming1,2，XIAOYifei1,RENHao1,andNIJun1.OilGeophysicalProspecting，2019,54(2)：447-455.

Conventional single-model machine learning methods used in tight-sand gas reservoir interpretation on well logging data have the multi-solution problem.To overcome this problem，we use the XGBoost algorithm.Based on logging data in the Area A，different types of well logging data are used as input variables，and a regression prediction model is established by XGBoost algorithm.The porosity and permeability in this area are predicted.The optimization of various parameters in XGBoost algorithm is also discussed.The classification prediction model established by XGBoost algorithm predicts reservoir types in the area.Based on our prediction results，the XGBoost algorithm achieves a better porosity & permeability prediction and tight-sand gas reservoir identification in the area compared with the random forest method and vector-supported machine algorithms.

Keywords：tight-sand gas reservoir，machine learning，XGBoost algorithm，well logging data interpretation

1.Institute of Geophysics and Geomatics，China University of Geosciences(Wuhan)，Wuhan，Hubei 430074，China

2.Hubei Subsurface Multi-scale Imaging Key Laboratory，Wuhan，Hubei 430074，China

Afractal-basedelectricalconductivitymodelandtheapplication.WANGJingxi1.OilGeophysicalProspecting，2019,54(2)：456-460.

A lot of research works both on theory and experiments have proved that the rock conductivity mainly depends on rock mineral composition and the pore geometry.However，the microstructure and conduction mechanism of real rock are fairly complicated.Factors affecting the changes of electrical characteristics are complex and diverse.As a consequence，it is difficult to characterize them accurately.There is a fractal property in pore space of reservoir rocks，and the variation trend of fractal dimension and porosity are in good agreement.To a certain extent，the fractal dimension can reflect the internal pore structure characteristics，providing an effective mean for quantitatively describing this complex feature.Based on the fractal theory，a conductive model is established for porous media.Practical applications are carried out with core and well logging data.The real data processing shows that the saturation results calculated by the fractal electrical conductivity model are in good agreement with the core analysis data，indicating the feasibility and effectiveness of the proposed method.

Keywords：fractal，electrical conductivity model，resistivity，porosity

1.Tongji University，Shanghai 200092，China

BasementdepthestimationbasedongravityanomaliesinWeiheBasinwith3Dvariabledensitycontrastmodel.FENGXuliang1,YUANBingqiang1,LIYuhong2，ZHANGJin’ai3，ZHANGLin3，andGUORuikun4.OilGeophysicalProspecting，2019,54(2)：461-471.

The depth estimation of the Precambrian basement of Weihe Basin is of great significance for the Paleozoic hydrocarbon exploration in the basin.Unfortunately，there is lack of understanding of the basement depth.The density of each sedimentary layer varies with depth，and it also changes in the horizontal direction.Therefore，the gravity inversion conducted with a constant density contrast cannot accurately delineate the basement depth.We fit the real density contrast of the sediments with 6 different density-depth functions according to 5 integrated geophysical sections and 3 boreholes’ information，which contains the density of every sedimentary layer in different tectonic units.Fitting-error statistical results of different functions indicate that the exponential density contrast-depth function is more coincide with the real density variation in Weihe Basin.Then the decay factorλand the density contrast Δρ0at the surface are extracted from the fitted exponential density contrast-depth functions，and the λ and Δρ0in the whole basin are acquired by gridding the discreteλand Δρ0.Thus，the 3D variable density contrast model is obtained by combination the griddedλand Δρ0in the whole area.Finally，this variable density contrast model is applied in Precambrian basement estimation of Weihe Basin，and the result indicates that the 3D density could be adopted to obtain a more accurate basement relief than the constant density contrast.This approach provides a strong basic data support for the hydrocarbon exploration in the basin and can also be very helpful for solving similar problems in other basins.

Keywords：3D variable density contrast model，gravity exploration，basement，density interface inversion

1.School of Earth Sciences and Engineering，Xi’an Shiyou University，Xi’an，Shaanxi 710065，China

2.Xi’an Center，China Geological Survey，Xi’an，Shaanxi 710054，China

3.Shaanxi Geological Survey Center，Xi’an，Shaanxi 710068，China

4.The 12th Oil Production Plant，Changqing Oilfield Company，PetroChina，Qingyang，Gansu 745400，China

EulerdeconvolutionofgravitygradiometrydataandtheapplicationinVintonDome.HOUZhenlong1,2，WANGEnde1,2，ZHOUWenna3，andWUGuochao4.OilGeophysicalProspecting，2019,54(2)：472-479.

In the mineral exploration and regional geological survey works，the gradiometry data is widely used because of its high precision.A new gradiometry Euler deconvolution is proposed in this paper combining three kinds of tensors of gravity gradiometry data，which can avoid errors from improperly selecting structural index and tensor transformation in calculations.Building theoretical models of single prism and dual prisms in different depths verifies that the proposed method can accurately inverse geological body depth and horizontal location.This method is applied to gradiometry data in Vinton Dome.The shape and distribution of cap rock top are depicted and new small-scale geological bodies are detected.The results agree very well with the known data，further enriches the underground structure information of this area.

Keywords：gravity gradiometry data，Euler deconvolution，joint inversion，Vinton Dome

1.Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines，Northeastern University，Shenyang，Liaoning 110819，China

2.School of Resources and Civil Engineering，Northeastern University，Shenyang，Liaoning 110819，China

3.School of Earth Sciences，Lanzhou University，Lanzhou，Gansu 730000，China

4.School of Earth Sciences，Zhejiang University，Hangzhou，Zhejiang 310058，China

Researchprogressonfracturenetworksimulationinshalereservoirs.LIYalong1,2,3，LIUXiangui2,3，HUZhiming2,3，DUANXianggang2,3，CHANGJin2,3，andZHOUGuangzhao2,3.OilGeophysicalProspecting，2019,54(2)：480-492.

The shale reservoir fracture network charac-terization is one of the most important issues of shale gas exploitation at the present stage.On the basis of the main controlling factors of fracture network expansion，it is an important link to select reasonable and advantageous experimental(test) and simulation methods to effectively promote shale exploitation.Through the investigation of a large number of field tests，laboratory experiments and numerical simulations，and research results of shale fracture network，the development and status quo of various numerical simulation methods are analyzed，the development direction of numerical simulation is predicted，and main controlling factors and influencing mechanism of fracture network are systematically summarized.Based on the above research，the following observations are obtained：A.Three numerical models of fracture network in shale reservoirs embody advantages and sustainable development：extended finite element model based on finite element model，unconventional fracture network model based on discrete fracture network model，and fractal fracture network model based on fractal theory; B.The fracture propagation in real strata is mainly controlled by fracture pressure，rock brittleness，in-situ stress，bedding，and natural fractures.Shale reservoir rocks are characterized by strong brittleness，well-developed bedding，and widely-distributed natural fractures，which greatly increases the complexity of fracture networks.On the whole，the fracture propagation is a result of the combined action of the above factors; C.At present，simulation methods of complex fracture network are based on different methods such as boundary element method，finite element method，discrete element method，and analytical method.Each method is suitable for a specific situation，so numerical methods for different situations are needed.

Keywords：shale，fracturing，fracture network spreading，expanded simulation，present situation，outlook

1.University of Chinese Academy of Sciences，Beijing 100049，China

2.Institute of Porous Flow and Fluid Mechanics，Chinese Academy of Sciences，Langfang，Hebei 065007，China

3.Research Institute of Petroleum Exploration & Development，PetroChina，Langfang，Hebei 065007，China