25 December 2013, Volume 48 Issue 增刊1

    

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  Noise suppression with box-wave in Tuolamu-Shenggen area, Qiangtang Basin

  Li Zhongxiong, Shi Dai, Lei Yang, Yu Wenke, Ma Long

  OGP. 2013, 48(增刊1): 1-6.

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  This paper discusses noise investigation by box wave method in Tuolamu-Shenggen area, Qiangtang Basin. Different kinds of noises can be found on Common receiver gathers. Using time slice and radar image scanning analysis, noise velocity, its propagation direction and its relative energy on the raw records can be obtained along with signal-noise ratio. Apart from ambient noise, we have found also four kinds of ground rolls, two kinds of linear noise, multi-refraction and refraction wave in this area. Meantime the results of suppressing noises by different geophone array lengths are analyzed and compared on the basis of areal analysis of box wave. The following conclusions can be drawn: A.The noises cannot be suppressed when geophone array length is zero; B.The ambient noises can be partly suppressed when geophone array length is 40 meters; C.The ground rolls can be primarily suppressed when geophone array length is 120 meters; D.Both the ambient noises and ground rolls can be suppressed much better when geophone array length is 160 meters; E.But for linear noise, multi-refraction and refraction wave, good suppressed results cannot be obtained even when geophone array length is 160 meters.
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  Intelligent quality control in high efficiency seismic data acquisition

  Shi Shuanghu, Deng Zhiwen, Duan Yingjie, Luofei, Zhou Heng, Li Bimin

  OGP. 2013, 48(增刊1): 7-11,46.

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  Simultaneous multi-vibrator-fleet shooting is a new and developing technology of high efficiency seismic acquisition. The paper focuses on quality control of high efficiency seismic acquisition based on conventional quality control methods in order to level up quality control and efficiency of data acquisition and processing. Usually massive supporting data files recorded by a recording system during high efficiency data acquisition need to be edited manually. This kind of workload is huge while its efficiency is low. To solve this problem, we firstly mentioned and realized the "integration of many quality control programs", and then embed the intelligent quality system in all the kinds of quality control methods such as vibrator attributes, COG (centre of gravity) of vibrators, sweep length, sweep type, geometry checking, and operation efficiency analysis. This intelligent quality system allows us to basically achieve "one-click" quality control. Field applications of this technology show that the intelligent quality system not only ensures seismic data quality but also improves operation efficiency.
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  Velocity model building based on grid tomography

  Li Hui, Cheng Dean, Jin Jing

  OGP. 2013, 48(增刊1): 12-16.

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  In the paper, we propose an optimized grid-tomography based velocity model building method for pre-stack depth migration. This method can make up limitations of the conventional tomography for vertical velocity model optimum. Usually it is very difficult to track horizons and velocity interfaces in low S/N ratio areas. In this case, this method is efficient. Applications in Daqing Oilfield indicate that the velocity model building method based on grid tomography is accurate and the algorithm is stable.
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  Anisotropic prestack depth migration imaging in deepwater area

  Xu Ziqiang, Dan Zhiwei, Wang Xinling, Fang Zhongyu, Li Sanfu, Guan Weilong

  OGP. 2013, 48(增刊1): 17-22.

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  Prestack depth migration is the most effective method for deepwater complex seafloor. This method can restore contorts and distortion of the subsurface caused by rough ocean bottom, and show true structures. At the same time it can solve bow-tie-effects in prestack time migration. However, due to the anisotropy of medium, seismic velocity changes with different incident angles. The isotropic depth migration often results in large depth errors with well logs. And the common imaging gathers are not flattened at far offsets. Therefore, anisotropic prestack depth migration shall be applied in deepwater seismic data processing. In this paper anisotropic prestack depth migration is applies to seismic data in South China Sea. In this paper, we focus on initial velocity field building and anisotropic parameter analysis, and analyze results of the anisotropic depth migration in the deep water area.
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  OBC dual-sensor data processing on the Echos processing system

  Xue Weizhong, Wang Shurong, Yang Xiaoyan, Liu Zhihua, Su Yan

  OGP. 2013, 48(增刊1): 23-26.

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  In this paper, we discuss an approach for reverberation suppression of OBC dual-sensor data. Based on analysis of its signal-to-noise ratio, phase and amplitude, field dual-sensor data are processed using reverberation suppression method of the Echos processing system. Dual-sensor data combined processing results show that both on single-shot stack record (two sensor data) and on stack sections, reverberations are well suppressed, and OBC data quality is greatly improved. Besides a combined processing flow for dual-sensor seismic data is formed.
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  Prestack migration imaging in a complex fault block of Dongpu Depression

  Li Chuanqiang, Meng Fanbing, Duan Xiaoyan, Li Shaokang, Ma Jianbo

  OGP. 2013, 48(增刊1): 27-30.

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  Dongpu Depression is geologically characterized by deeply-buried targets, complex fracture systems and thin beds. In order to accurately depict complex subsurface fracture system, we have conducted prestack migration imaging approach including prestack data regularization, high density automatic velocity picking, anisotropic migration and curved ray migration etc. Based on high density 3D seismic data, this approach improves greatly 3D seismic data imaging, and provides reliable final results for future exploration and development.
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  2D seismic data processing methods in the Block D, West China

  Zhang Gaocheng, Zhou Gang, Si Wei, Zhang Juan, Yang Dan

  OGP. 2013, 48(增刊1): 31-35.

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  This paper discusses some seismic data processing methods in the Block D of West China. In order to improve seismic data imaging, first we use to mographic static correction, apply multi signal reconstruction to eliminate the surface waves and multi-domain combination to remove linear noise, and adopt high-precision Radon transform to remove multiples. Then, using constant phase rotation and surface-consistent approach, we perform wavelet shaping due to different seismic source such as dynamite and vibroseis. For enhancing the precision of migrated imaging, we build accurate velocity model, and use Kirchhoff prestack time migration. On final seismic sections, the signal-to-noise ratio is greatly improved, the imaging is accurate, and both wave group characteristics and various structural shapes are clear.
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  Multiple attenuation by prestack migration in the OVT domain

  Duan Wensheng, Li Fei, Li Shiji, Huang Luzhong, Peng Gengxin

  OGP. 2013, 48(增刊1): 36-41.

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  Through research on the OVT, we have found that prestack migration in the OVT domain can suppress multiples. Using high density seismic data (small trace interval), we extract offset vector tiles and analyze reasons of multiple attenuation by prestack migration in the OVT domain. We conclude that the main roles of multiple attenuation by prestack migration in the OVT domain is that the OVT gathers have larger offset range than common offset gathers.
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  Shot domain wave equation in foothill seismic data processing

  Xu hui

  OGP. 2013, 48(增刊1): 42-46.

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  Complicated foothill areas have some geological characteristics such as undulating surface, large angle of underground overthrust nappe structure, stratigraphic inversion overlap and complex fault formation. On seismic data, we see mainly low signal-to-noise ratio and huge velocity vertical and horizontal variation. It is difficult to build high precision velocity modeling, and conventional seismic imaging method does not work. Therefore, we have adopted some approaches. We use constrained velocity inversion (CVI) to establish the initial velocity model for solving the problem of unstable velocity field. We build velocity model with 3D tomography and well constrained velocity modeling. We use shot domain wave equation prestack depth migration to the full aperture migration in order to solve the structural imaging problem in complicated foothill area.
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  Tight thin reservoir prediction in Maling Oilfield

  Zhang Jie, Zhao Deyong, Zhao Yuhua, Wang Daxing, Wang Yongli, Huang Ligang

  OGP. 2013, 48(增刊1): 47-52.

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  In the Chang 81 formation, Maling Oilfield, Ordos Basin, there are two sets of tight sands, viz. Chang 811 and Chang 813. The tight sands are thin with sharp lateral variation. This paper discusses some approaches for tight thin sand prediction. Using both self-organizing neural network waveform classification and frequency decomposition, we characterize this kind of thin reservoirs based on seismic forward modeling, and also predict their distributions. The predictions are mutual corroborated by these two approaches. Results show that our approaches are efficient.
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  Application of prestack joint inversion of P-and S-waves

  Guo Ping, Zhang Shumei, Zhang Gao, Zhong Qiang

  OGP. 2013, 48(增刊1): 53-57.

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  Prestack joint inversion of P-and S-waves makes full use of the prestack AVO information and other information provided by well logging, drilling and geological data, such as the structure, horizon, lithology information. So this approach can obtain more accurate elastic parameters of oil bearing lithology, and improve reservoir characterization. Gainan-Longwangmiao structural belt of Liaohe Oilfield is located in multiple sediment source junction area. Dongying formation reservoir changes greatly in lateral direction. It is difficult to identify spatial distribution and the source direction of hydrocarbon-bearing sand bodies. This directly affects sedimentary system analysis. Conventional seismic inversion cannot meet the requirements of sand body distribution prediction. Therefore, we have conducted prestack joint inversion of P-and S-waves with rock physics analysis. The results show that this approach has obtained abundant elastic parameters and revealed the reservoir distribution.
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  Coalbed methane prediction in Huhehu Depression, Hailar Basin

  Xie Chunlin, Guan Xiaowei, Zhang Guangying, Wang Jinwei, Zhang Wanting

  OGP. 2013, 48(增刊1): 58-63.

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  Huhehu Depression in Hailar Basin is characterized by thick coal seams at moderate depth, which shows good conditions for coalbed methane reservoir forming. However, coal seam characteristics on seismic sections are not clear. In this paper we propose approaches to predict coal seams and coalbed methane distribution on seismic data. First we analyze petrophysical characteristics of coal seams and coalbed methane, and then we apply impedance inversion to predict coal seam thickness. We also analyze AVO characteristics of coal seams in this area and predict coalbed methane distribution by AVO inversion. Hopefully these approaches will provide necessary preparations for coalbed methane exploration in Huhehu Depression, Hailar Basin.
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  Total organic carbon content prediction of gas-bearing shale with geophysical methods

  Xu Jie, He Zhiliang, Dong Ning, Huo Zhizhou, Lu Jing, Zhang Jinqiang, Li Pei

  OGP. 2013, 48(增刊1): 64-68.

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  According to Jurassic continental shale gas in JN area, the eastern Sichuan Basin, this paper discusses difficulties and problems in predicting total organic carbon content (TOC) of gas-bearing shale, and puts forward some geophysical prediction methods. Based on organic matter characteristics, we first discuss rock physics analysis and TOC prediction conditions, and use a geostatistical inversion to calculate TOC. Using TOC curve building, seismic interpretation, constrained sparse spike inversion and geostatistical inversion, TOC distribution in vertical and lateral are calculated. This technique is successfully applied in JN area and above 90% predictions are proved. The results show that this technique can effectively identify TOC distribution, and will support for horizontal well drilling in shale gas.
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  Shale brittleness prediction by geophysical methods

  Dong Ning, Xu Jie, Sun Zandong, Lu Jing, Zhou Gang, Liu Zhishui

  OGP. 2013, 48(增刊1): 69-74.

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  Taking the Jurassic continental shale gas of the JN area on the Eastern Sichuan Basin as an example, this paper discusses difficulties and problems in predicting shale brittleness, and puts forward some geophysical prediction approaches. Based on shale rock physics modeling and analysis of shale brittleness characteristics, a pre-stack elastic parameter inversion is applied to calculate the shale brittleness. Based on approximate Zoeppritz equation and Bayesian parameter estimation theory, this method uses the covariance matrix to describe parameter correlation degree. And then the inversion results are constraints by rock physical relationship between parameters, and get shale information about longitudinal wave, shear wave and density, and finally obtain quantitative description of shale brittleness. The brittleness index of seismic prediction has better consistency with brittleness mineral content by examining.
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  Geological grid technology for 3D geology modeling in complex fault-block reservoirs

  Xu Fang, Zhang Wenqi, Li Juhong, He Shumei, Liu Tianhe

  OGP. 2013, 48(增刊1): 75-81.

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  3D geological model is one of the reservoir geology study final results.However,there are many limitations in establishing an accurate complex structural model and properties model of strong heterogeneity reservoir using common modeling softwares and mathematical algorithms. In this paper, we propose geological grid approach for structural model. This approach is used in Z fault block of Dagang Oilfield. This approach has no grid distortions as the conventional PILLAR grid system has. Moreover, it ensures structure completeness and accuracy. Using facies-controlled multi-variogram analysis, reservoir spatial distribution and physical changes are accurately characterized. Therefore, fast micro-faices change and strong he-terogeneity in reservoirs are well described. And a more realistic reservoir geological model is provided for future oilfield development.
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  Red layer reservoir characterization in the Dongying Depression

  Pan Xingxiang

  OGP. 2013, 48(增刊1): 82-88.

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  Many sets of red clastic rock formations are developed in Ek3 to Es4s in the southern part of Dongying Depression. They are inter-beds of sandstone and mudstone interspersed with multi-period basalt. Low seismic data resolution and small velocity difference between the deeply buried inter-beds make reservoir prediction very difficult. Based on the rock physics analysis, we obtain the reflection characteristics by well logging and seismic calibration, and choose sensitive seismic attributes by the forward modeling. As the result, a series of seismic reservoir prediction approaches are formed for red layer with different facies in different plays. Based on our research, using multi-attributes can identify reservoirs from the surrounding rocks in the basin. On slope denuded belts, the sandstone velocity is obviously higher than the mudstone velocity, and the instantaneous amplitude reflects the distribution pattern of sandstone. On step-fault belts and sags, the prestack attribute such as the velocity ratio between P-wave to S-wave reflects sandstone features, and the sandstone distribution is predicted with prestack AVO attributes and other information.
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  Integrated fluid prediction for carbonate reservoir

  Zhang Junlin, Tian Shicheng, Zheng Duoming, Lu Jianlin

  OGP. 2013, 48(增刊1): 89-94.

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  It is a real challenge to predict hydrocarbon in carbonate reservoir in the western Northern Tarim Uplift because carbonates in the region have strong heterogeneity. According to our experience, the Probe AVO software is more effective to predict fluid in fracture-cavity carbonate reservoir than conventional post-stack fluid attributes. Using automatic residual NMO, median filter and amplitude equalization, we reduce partially AVO pseudomorph caused by non-reservoir and non-hydrocarbon. It proves that AVO response aroused by hydrocarbon bearings is more obviously than water bearings in carbonate reservoir after utilizing fluid substitution and AVO forward modeling. Meanwhile, we utilize well logging data interpretation to predict fluid in carbonate reservoir to reduce prediction risks.
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  The characterization of fractures in carbonate reservoirs by full azimuth seismic data

  Ji Xuelin

  OGP. 2013, 48(增刊1): 95-98.

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  In onshore seismic exploration, standard migration technologies have traditionally been unable to provide sufficient detail and accuracy when imaging subsurface carbonate reservoirs. A new method was required to provide higher-quality depth images and reservoir characteristics, to both enable a more correct placement of exploration and production wells, and to improve production flow.
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  “Sweet spot” prediction of inter-salt argillaceous dolomite reservoir in Wangchang area

  Zha Shugui, He Youxiong, Mo Li, Han Bing, Niu Lihuan

  OGP. 2013, 48(增刊1): 99-103.

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  In Qianjiang Depression, China, inter-salt argillaceous dolomite covers an area of 1800km², and there are 193 cyclothems of grade Ⅲ. According to the third resource evaluation, oil generation volume may have as much as 43×10⁸ tones in the argillaceous dolomite in Qianjiang Depression. And oil resources can reach 1.68×10⁸ tones. The Wangchang area in Qianjiang Depression is considered as the most favorable area for inter-salt argillaceous dolomite reservoir-forming. Inter-salt argillaceous dolomite in the area is a typical unconventional reservoir. "Sweet Spot" is mainly controlled by oil-bearing property and reservoir conditions. Through petro-physics, seismic facies, pre-stack elastic parameter inversion, azimuth anisotropy research, and combined with the geological knowledge, "sweet spots" of 10th rhythm member in Qian 3 oil formation is predicted in Wangchang area.
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  Identification and characterization of carbonate cavern system, and its genetic analysis

  Gao Jun, Yang Yu, Dai Shuanghe, Xu Pan, Qian Junxin, Guo Zenghu, Tang Yanhong

  OGP. 2013, 48(增刊1): 104-108.

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  In this paper, we conduct identifications, characterizations and genetic analysis for the Cretaceous Kh1-Ma3 carbonate cavern system in AD Oilfield in the Middle East. The cavern system is comprised of sink holes, underground streams, and fissure distributes in spatially reticular structure. And the cavern system is characterized by multiple stages (at least 3 stages), zonality and low porosity and permeability. This kind of characteristics in the cavern system plays a role of vertical sealing and lateral barrier against hydrocarbon migration, thus forming an enclosed area that is nearly "box-like". Consequently, in Mi1-Ma3 layers of the Well B1-C1 Block where the cavern system is developed, hydrocarbons are hard to be filled and accumulated. In contrast, Karst is not developed from shallow to deep layers in the Well A1 Block, which is good for preservation of porous reservoirs with bioclastic limestone matrix and for multi-series hydrocarbon accumulation. The analysis of reticulated cavern system and its impact on hydrocarbon accumulation has been effectively verified by drilling data.
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  Hydrocarbon detection with AVO in Block Su-75

  Liu Dongqin, Li Xiaoheng, Wang Guanmei, Liu Liangqiong, Li Haiying, Zhang Chenyu

  OGP. 2013, 48(增刊1): 109-114.

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  Sedimentary difference between the eastern and western of Block Su-75 in Sulige Gasfield causes characteristic differences in seismic data, gas reservoirs position, and AVO response. It is difficult to predict reservoir using single parameter and hydrocarbon indictor attributes obtained from AVO analysis. Based on CMP gathers analysis, forward modeling of gas-reservoirs theoretical model and gas-reservoirs actual model passing through a well, the absolute amplitude value of reflections from gas reservoirs increases with the offset no matter what AVO response polarity is from the reservoir top and bottom. So AVO can be used to detect effectively the thicker gas-bearing. Our research identifies the gas bearing distribution in Block Su-75 using pseudo poisson's ratio and pseudo shear wave reflective coefficient. The result is highly consistent with the well drilling data, which provides a strong support for the future oil and gas exploitation in the area.
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  Glacial reservoir identification and evaluation

  Xie Jielai, Zhang Yuxiao, Li Zhengzhong, Dai Shuanghe, Chen Yuanzhong, Guo Zenghu

  OGP. 2013, 48(增刊1): 115-119.

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  Glacial reservoir rocks are characterized by their variable thickness, quickly-varied lithology and highly lateral heterogeneity. So it is difficult to identify and evaluate this kind of reservoir rocks in oil & gas exploration. According to the reservoir features of glacial sand in D'M layer of Ordovician in the Block X, Algeria, first we have accurately identified the thickness and the distribution of sands using seismic half energy time attribute. Then we have evaluated reservoir efficiency using fluid mobility. Results are proved as a breakthrough of deep stratum oil & gas exploration in this block.
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  Geometric attribute improved-processing in fault interpretation

  Fang Haifei, Zhou Shang, Wang Yongli, Han Tianbao, Cheng Peng, Feng Ruowu, Zhang Ying, Li Changfen

  OGP. 2013, 48(增刊1): 120-124.

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  As geometry attributes describe the spatial pattern of seismic reflection, so it is widely used for fault identification in structural interpretation. However, a single geometric attribute cannot accurately characterize all the kinds of faults. This paper reviews a series of seismic attribute improved-processing technology developed in recent years such as seismic data filter processing, curvature cube, attribute-proportion fusion, multi-attribute cube fusion, and imaging-based fusion. Applications of these approaches improve effectively fault identification.
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  Structural-lithological reservoir interpretation in Lixian gentle slope belt, Raoyang Sag

  Wang Yongli, Zhou Shang, Li Nan, Gao Xiaoli, Zhang Wanfu, Zhang Ying

  OGP. 2013, 48(增刊1): 125-130.

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  This paper focuses on structural-lithological reservoir interpretation on Lixian slope in Raoyang sag, Jizhong Depression, Bohai Bay Basin. According to stratigraphic-lithologic reservoir characteristics of gentle slope belt and geologic characteristic of Lixian slope, we use four technical series. Firstly, using virtual reality technology, we conduct fine structure interpretation of tectonic setting of Lixian slope. We have found 3 large nosing structures with east-west direction. Secondly, using the sequence stratigraphy method, we describe exactly strati-lithologic traps, and we have found favorable facies belt of lithologic reservoir under the control of sequence stratigraphic framework. Thirdly, using multi-attributes such as coherence, curvature, edge detection, and attribute fusion, we describe minor faults and low-relief traps. Fourthly, using logging-constrained inversion and seismic attributes, we predict exactly reservoir boundaries. Finaly, this study has made a great success in the area, and one hundred million tons of oil reserves have been discovered.
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  Seismic stochastic inversion based on logging sensitive attributes reconstruction

  Che Tingxin, Huang Yanzhang, Liu He

  OGP. 2013, 48(增刊1): 131-138.

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  Taking Wunan Depression in Hailar Basin as an example in this paper, a stochastic inversion based on logging sensitive attributes-reconstruction is used for reservoir prediction, and all the key aspects of data processing in the course of inversion are discussed, such as logging curve editing and correction, determining sensitive logging parameters and the logging sensitive attributes-reconstruction-based stochastic inversion. Inversion results show that this method improves the resolution and accuracy of reservoir prediction, and the predicted sandstone thickness is consistent with the drilling results.
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  Identification and characterization of lithological traps within sequence stratigraphicframework -a case study of South Turgay Basin, Kazakhstan

  Yan Geng, Kong Linghong

  OGP. 2013, 48(增刊1): 139-145.

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  Stratigraphic/lithologic traps are playing an increasingly important role as hydrocarbon reserves and productions from them are growing. Focusing on three dominating types of lithological traps in South Turgay Basin, i.e. channel sand body, up dip wedge-out and buried hills, this paper introduces a two-step work flow for identification and characterization of lithological traps. The first step is to setup the sequence stratigraphic framework and to qualitatively describe the type, characteristics and distribution of lithological traps. The second step is to quantitatively characterize the shape, thickness and physical properties of the traps by some seismic reservoir prediction approaches. This work flow has been proved to be effective in the exploration practice in South Turgay Basin for above-mentioned three types of lithological traps.
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  Exploration potential in the Block X in South Turgay Basin, Kazakhstan

  Li Haiying, Hong Yueying, Mo Aling, Ding Changhui, Zhang Xiuqi

  OGP. 2013, 48(增刊1): 146-150.

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  Based on merged 3D seismic data, we conduct a study of stratighaphy, faults and structures in the Block X, South Turgay Basin, Kazakhstan. Using seismic attributes, we analyze amplitude anomalies of some layers. The following observations are obtained: A. A continuously developed uplift in the Paleozoic basement might be a preferable target for hydrocarbon migration; faults together with unconformity and permeable sandstones in the area form a nice dredge system for hydrocarbon. B. Adjacent to oil source and presented as high, buried hills with developed fractures in the basement may be favorable drilling targets. C. Structures or traps close to oil source at shallow depth may be also favorable targets for the future exploration.
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  An enhanced method for modeling internal architecture of point bar sand bodyin meandering alluvial rivers

  Shu Xiao, Zhao Yongjun, Wang Bingjie

  OGP. 2013, 48(增刊1): 151-156.

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  This paper proposes an enhanced method for modeling internal arechitecture of point barsand body. First a migration model of meandering rivers is established based on hydraulic equations. Then the location of point bar sand body generated is determined according to the curvature of centerlines. And the lateral accretion beddings and lateral accretion body are sequentially simulated under the control of erosion coefficient. Finally, the coupled numerical model is established. The applications in Nen River show that this method reproduces not only the curving geometries of channels, but also accurately characterize the shape of point bar and the arrangement relationship of internal architecture elements. At the same time, the simulation result coincide with real geological case as this method can incorporate geological data as much as possible by using erosion coefficient map. So this method is an effective modeling method.
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  Tectonic evolution characteristics and mechanism in Western Hunan-Hubei

  Chen Yuming, Gao Xingxing, Sheng Xiancai

  OGP. 2013, 48(增刊1): 157-162.

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  This study is conducted based on 2-D seismic data and field geological survey data in Western Hunan-Hubei. The following observations are obtained: A.The area is a complex mountain-basin system formed by the Jiangnan-Xuefeng Orogenic belt and its foreland thrust belts, and the East Qingling-Dabie Orogenic belt and its foreland thrust belts, which comprises a regional geologic structure with a basin intervening between two mountains; B.The multi-phase tectonic movements since the basement formed resulted in a complicated tectonic evolution history and characteristics with a variety of tectonic styles. As a whole, structures are characterized by ramp fringe, north-south zonation, and vertical superimposition. Locally, two-layer structures occur. In addition, the mechanism for evolution and formation is summarized in the paper.
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  Fine evaluation of extra-low permeability reservoirs based on the multi-well logging evaluation

  Li Xia, Shi Yujiang, Li Changxi, Hu Song

  OGP. 2013, 48(增刊1): 163-169.

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  With a strong heterogeneity and oil-bearing property, the member Chang 8 reservoir of Yanchang Formation in Jiyuan area, Ordos Basin is characterized by typical extra-low permeability. And it has complex reservoir parameters and reservoir distribution. This paper proposes an approach for evaluation of this kind of reservoirs. Based on core calibrating logging data, we build fine interpretation models of reservoir parameters according to logging data standardization. Through multi-well logging interpretation, the reservoir distribution and oil-bearing property are determined. Small sand bodies are identified based on different logging facies, and lithologic reservoir contrast is obtained by different physical and oil-bearing properties. Finally the control factors and distribution rules of extra-low permeability reservoirs in the area are defined. Therefore fine evaluation of extra-low permeability reservoir is realized based on multi-well logging.
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  Petrophysical evaluation on multi-layer sandstone reservoirs in GU Oilfield

  Yang Jingqiang, Liu Ru-hong, Zhang Liqiu, Peng Dandan, Wang Chunyang

  OGP. 2013, 48(增刊1): 170-174,185.

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  This paper introduces petrophysical evaluation on multi-layers sandstone reservoirs in GU area by logging data QC and data preprocessing, multi-mineral model selection, saturation model selection and cutoff determination. Actual data analysis suggests that cross-plots and frequency graphs are very useful in data QC and cutoff determination. Dues to lack of core analyzed saturation data in the work area, in this paper we focus on the comparison between the water saturation calculated by resistivity model and that derived by J-function. Based on the universally-adopted workflow of thickness division, the thicknesses of gross sand, net sand and net pay are reasonably divided using cutoff of clay volume, porosity and water saturation.
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  Application of multi-mine soft model in a shale oil & gas reservoir logging evaluation

  Qin Ruibao, Yu Jie

  OGP. 2013, 48(增刊1): 175-180.

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  Logging response characteristics in shale oil & gas reservoirs are different from that in conventional reservoirs, mudstones and calcareous rocks. Shale oil & gas reservoirs usually have the response characteristics of high natural gamma, high compensated neutron, high resistivity, high compressional wave slowness, low bulk density and low photoelectric absorption index. And their rock physical volume models are more complex than that of conventional reservoirs. Using conventional well logging data the accuracy of reservoir parameter interpretation cannot be good. In this paper, an optimized approach from multi-mine soft model is applied to calculate mineral volumes, porosity, water saturation and total organic content through jointly using conventional logging and elemental capture spectroscopy logging data and establishing the mineral volume model. We also discuss evaluation methods of shale oil & gas reservoir parameter and these parameters are important in the evaluation of shale oil & gas reservoir.
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  Joint inversion of logging and seismic data for geosteering risk control

  Zhu Weixing, Yang Yuqing, Zhao Yongsheng, Peng Jinyong, Zhang Chunze, Lin Longsheng

  OGP. 2013, 48(增刊1): 181-185.

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  Using current geology data and reservoir data near the drill bit, geosteering can adjust horizon well drilling trajectory to guide the bit lateral drilling in oil reservoir. Logs simulated by the geosteering model for the current well are interpolated directly from logs of the adjacent well. These simulated logs cannot show layer heterogeneity, therefore it cannot ensure the horizon well drilling trajectory in a good reservoir. For this reason, the article inducts a log-constraint seismic impedance inversion method to modify geosteering model and predict target heterogeneity, so that it can control the drilling trajectory in the good physical property place of reservoir. The geosteering results of real horizon well drilling indicate that geosteering model modified by log-constraint seismic impedance inversion can well guide horizon well drilling trajectory, reduce risks, and increase the reservoir drilling rate.
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  Reservoir characteristics of Sha-1 member in C9 block, CYT Oilfield, Liaohe Basin

  Xiao Xiong, Xu Xiaohong

  OGP. 2013, 48(增刊1): 186-190.

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  The member Es₁ of C9 block in CYT Oilfield is a major hydrocarbon containing target, which is mainly the fan delta front deposits. Based on core analysis, log interpretation, and sedimentary microfacies, we conduct a research on lithology characteristics, physical property and reservoir heterogeneity. The results show that the reservoir rock of C9 block is mostly quartz sandstone and reservoir physical property is a sandstone reservoir with medium-high pore and medium-high permeability. Affected by sediment source, physical property gradually become worse from northeast to southwest. The reservoir shows a strong heterogeneity according to the analysis of permeability variation coefficient, onrush coefficient, permeability differences. This study provides useful information for the future reservoir development.