Summary HQ 3D survey was acquired with full azimuth geometry. In order to take full use of its valuable azimuth information, we proposed a full azimuth tomography workflow in OVT domain to build an earth model. After comparing three workflows for velocity modeling, we demonstrate that this new workflow can resolve small scale velocity changes by using the azimuth information from seismic data, while conventional approach for velocity modeling cannot invert these short-wavelength changes due to lack of azimuth data. We can also see that PSDM butterfly gathers using conventional modeling strategy showed obvious azimuthal moveout variations, but those through full azimuth inversion in OVT domain were flattened much better, and hence depth imaging of target carbonate caves was improved greatly. We conclude that OVT-based full azimuth tomography workflow provides a very efficient, effective and high resolution velocity estimation procedure.

This paper introduces horizon control, seismic control, logging control and facies control methods through the application of the least squares fitting of logging curves, seismic inversion and facies-controlled techniques. Based on the microgeology and thin section analyses, the lithology, lithofacies and periods of the Permian igneous rocks are described in detail. The seismic inversion and facies-controlled techniques were used to find the distribution characteristics of the igneous rocks and the 3D velocity volume. The least squares fitting of the logging curves overcome the problem that the work area is short of density logging data. Through analysis of thin sections, the lithofacies can be classified into eruption air-fall subfacies, eruption pyroclastic flow subfacies and eruption facies.

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2013PSDM-oriented processing workflow for topographic PSDM in thrust beltsAuthors: Ying HuLing XuChunming WangYongke HanHuiwen XieChao WuYing HuResearch Institute of Petroleum E & P, PetroChinaSearch for more papers by this author, Ling XuResearch Institute of Petroleum E & P, PetroChinaSearch for more papers by this author, Chunming WangResearch Institute of Petroleum E & P, PetroChinaSearch for more papers by this author, Yongke HanResearch Institute of Petroleum E & P, PetroChinaSearch for more papers by this author, Huiwen XieTarim Oil Field Ltd.Search for more papers by this author, and Chao WuTarim Oil Field Ltd.Search for more papers by this authorhttps://doi.org/10.1190/segam2013-0517.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract PSDM from rugged topography has become an effective solution to complex structure imaging in mountain areas in theory. However, it's hard to achieve reasonable PSDM results in western China thrust belts. The key issues are how to prepare data for PSDM and how to build velocity model from topography. In practice, most of velocity modeling algorithms is based on the curvature features of CMP or CIP gathers processed by conventional data processing workflow which satisfies hyperbolic assumption. The static correction for low velocity zone replacement using a constant velocity could distort the travel time curvature of seismic data in mountain areas, and lead to misunderstanding of the imaging velocity. In this paper, we propose a novel preconditioning workflow for PSDM from topography. Firstly, we pick the first break and inverse the near surface velocity by tomography algorithms. Based on inversed results, we apply a topography-related first break residual static correction to keep the shape of topography and the near surface velocity features in mountain areas. Secondly, we attenuate abnormal strong energy noises, and implement surface consistent amplitude compensation. Thirdly, we combine near surface and subsurface velocity together to build hybrid model. Finally, we apply certain PSDM to update velocity model iteratively. Based on this unconventional preprocessed data, we could build velocity model with higher precision; and achieve high quality PSDM results in western China thrust belt. Compared with PSDM from real topography without any static correction, our processing method is more practical for low signal to noise ratio seismic data in mountain areas with irregular topography. Permalink: https://doi.org/10.1190/segam2013-0517.1FiguresReferencesRelatedDetails SEG Technical Program Expanded Abstracts 2013ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2013 Pages: 5258 Publisher:Society of Exploration Geophysicists HistoryPublished Online: 19 Aug 2013 CITATION INFORMATION Ying Hu, Ling Xu, Chunming Wang, Yongke Han, Huiwen Xie, and Chao Wu, (2013), "PSDM-oriented processing workflow for topographic PSDM in thrust belts," SEG Technical Program Expanded Abstracts : 4076-4079. https://doi.org/10.1190/segam2013-0517.1 Plain-Language Summary PDF DownloadLoading ...

Abstract The Kuqa foreland thrust belt, which has superior petroleum geological conditions and lines of structural belts, is an important target for natural gas exploration in Tarim basin. But owing to the bad surface conditions, the complex deformation of the underground structures and the poor quality of seismic data here, it is difficult to define the trap and evaluate the reservoir. Since the discovery of the Kela 2 gas field and the Dina 2 gas field, there was no further progress at one time. Recently, a serie of technique research aimed at the targeting Cretaceous subsalt rocks strata in Kuqa foreland thrust belt has been carried out: The application of wide line and large geophone array seismic acquisition technique in complex mountainous areas can effectively improve the quality of seismic data; With 3D anisotropy seismic pre-stack migration technique, the seismic imaging and migration homing problem of the complex over-thrust and the irregular object is effectively resolved; The modeling technology of the compressive salt-related structures effectively guides the high and steep complicated structure interpretation; The technique of recognizing and forecasting of the thick conglomerate layer in shallow strata can be applied to build the seismic velocity field and confirm the traps. The great progress in exploration technology has enriched the geological understanding and brought about three major changes in exploration: In Kelasu structure zone, the exploration target turns to deep strata from the shallow ones; In eastern Kuqa depression, it goes to tight sand gas exploration while in the western part it switches to the lithologic hydrocarbon reservoir exploration. In this way, the subsalt layer hydrocarbon exploration has made a great breakthrough, companied with a new gas exploration upsurge. In five years, Dabei-3, Keshen-2, Keshen-5, Bozi-1, Keshen-8 and many other gas reservoirs have been found. 800 billion cubic meters of natural gas has been confirmed and about 30 important traps have been reserved. The total natural gas reserves amount has exceeded 2 trillion.

In this paper,the seismic inversion combined with the well logging,rock physics,seismic facies and the forward modeling was used to comprehensively study the characteristics of the igneous rocks. The rock physics experiment is a useful tool to study the physical property parameters of the igneous rocks. The analysis of the experimental data is helpful to predicting the igneous lithology and velocity. On such a basis,the seismic inversion is used to describe the igneous rocks by the seismic data. The environmental correction and standardization of the original logging curves is the prerequisite for high quality synthetic seismogram and inversion. The constrained sparse spike inversion,the model based inversion and the neural network inversion have higher resolution than the original seismic data. The spatial distribution of igneous rocks can be identified by them,with the model based inversion having the highest resolution. The GR characteristic inversion has higher resolution than the above-mentioned three methods. However,as a single characteristic can hardly be used to describe the characteristics of igneous rocks,the multi-parameter seismic inversion is an efficient way. The seismic facies is also used to obtain the igneous 3D velocity field. The precision of the velocity field is verified by the error analysis and forward modeling.

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2011Application of reverse‐time migration into complex structure image in mountainous areasAuthors: Wenbo SunSam Zandong SunChengzao JiaHuiwen XieShan JiangPei YangDi WangWenbo SunLab for Integration of Geology and Geophysics (LIGG), China University of Petroleum (Beijing)Search for more papers by this author, Sam Zandong SunLab for Integration of Geology and Geophysics (LIGG), China University of Petroleum (Beijing)Search for more papers by this author, Chengzao JiaCNPCSearch for more papers by this author, Huiwen XieTarim Oilfield Co., CNPCSearch for more papers by this author, Shan JiangLab for Integration of Geology and Geophysics (LIGG), China University of Petroleum (Beijing)Search for more papers by this author, Pei YangLab for Integration of Geology and Geophysics (LIGG), China University of Petroleum (Beijing)Search for more papers by this author, and Di WangLab for Integration of Geology and Geophysics (LIGG), China University of Petroleum (Beijing)Search for more papers by this authorhttps://doi.org/10.1190/1.3627870 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract The surface conditions and subsurface structure are quite complicated on the land of western China, so quality of seismic data acquired is rather poor. The problems of noise suppression and static correction are extremely challenging. Correspondingly, the problems above have a significant influence on seismic image. For the reason, the paper adopts a series of pre‐stack processing techniques to focus on the issues. Noise is eliminated in different domains. Meanwhile, different methods are also employed to attenuate noise according to different topography; Analog annealing method is used to solve the problem of static as well, especially suitable to use in the data of mountainous areas. Then, reverse time migration (RTM) is applied on this land data. Subsequently, the image obtained is compared with that of Kirchhoff PSDM. The comparison demonstrates that RTM has some advantages in complex structure image, especially steep dip image. Additionally, angle domain CIGs generated by using RTM, are compared with the offset domain CIGs produced by Kirchhoff migration in the complex velocity zone. It is obvious that quality of angle gathers are better than that of offset gathers, which is potential for discriminating whether velocity is correct or not.Permalink: https://doi.org/10.1190/1.3627870FiguresReferencesRelatedDetailsCited byImproving Complex structure Image by Reverse Time Migration in Mountainous AreasYalin Li, Guangming He, and Chuanwen Sun25 October 2012 SEG Technical Program Expanded Abstracts 2011ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2011 Pages: 4424 Publisher:Society of Exploration Geophysicists HistoryPublished Online: 25 May 2012 CITATION INFORMATION Wenbo Sun, Sam Zandong Sun, Chengzao Jia, Huiwen Xie, Shan Jiang, Pei Yang, and Di Wang, (2011), "Application of reverse‐time migration into complex structure image in mountainous areas," SEG Technical Program Expanded Abstracts : 3248-3252. https://doi.org/10.1190/1.3627870 Plain-Language Summary PDF DownloadLoading ...