3-D seismic interpretation of stratigraphic and structural features in the Upper Jurassic to Lower Cretaceous sequence of the Gullfaks Field,Norwegian North Sea:A case study of reservoir development

The 3-D seismic dataset is a key tool to analyze and understand the mechanism of structural and stratigraphic hydrocarbon(HC)trapping in the subsurface.Conventionally used subsurface seismic characterization methods for fractures are based on the theory of effective anisotropy medium.The aim of this work is to improve the structural images with dense sampling of 3-D survey to evaluate structural and stratigraphic models for reservoir development to predict reservoir quality.The present study of the Gullfaks Field,located in the Norwegian North Sea Gullfaks sector,identifies the shallowest structural elements.The steepness of westward structural dip decreases eastward during the Upper Jurassic to Lower Cretaceous deposition.Reservoir sands consist of the Middle Jurassic deltaic deposits and Lower Jurassic fluvial channel and delta plain deposits.Sediment supply steadily prevails on sea-level rise and the succession displays a regressive trend indicated by a good continuous stacking pattern.The key factor for the development of reservoirs in the Gullfaks Field is fault transmissibility with spatially distributed pressure.The majority of mapped faults with sand-to-sand contacts are non-sealing,which provide restriction for the HC flow between the fault blocks.The traps for HC accumulation occur between the post-rift and syn-rift strata,i.e.antiform set by extensional system,unconformity trap at the top of syndeposition,and structural trap due to normal faults.Overall reservoir quality in the studied area is generally excellent with average 35%porosity and permeability in the Darcy range.Our findings are useful to better understand the development of siliciclastic reservoirs in similar geological settings worldwide.

Moderate Interpretation with Attribute Analysis and 3d Visualization for Deeper Prospects of Balkassar Field, Central Potwar, Upper Indus Basin, Pakistan

Balkassar is an old field with considerable remaining potential. The 2d, 3d seismic and earlier vintages show that Balkassar is composed of two folds that impart heart shaped geometry. It appears likely the early Eocene age Bhadrar formation may provide commercial production with lower water cuts from the eastern lobe (yet untapped) of the structure that may have at least 30 million barrels of unrecovered oil. Horizontal drilling may have promise as an optimum technique for recovery of oil from Paleogene reservoirs. Encouraging oil indications have also been recorded from the early Permian age tobra formation from Balkassar oxy-1 that was not tested by Oxy. Tobra sandstone reservoir can have a matrix porosity approaching 8%. When fractured recoveries from it can be relatively better than the Paleogene reservoirs. The 2D and 3D seismic acquisition has confirmed that the eastern lobe (yet untapped) of the Balkassar field is structurally higher and steeper than the Western lobe which has thus far produced over 30 million barrels. The Eastern lobe thus offers good potential for recovery of oil from the Bhadrar reservoir. The entire field is likely to have potential for recovery of oil from the early Eocene aged Tobra formation. 2-d and 3-D Seismic data interpretation, attribute analysis and visualization for deeper prospect carried in Balksasar field. Tobra and Khewra formation studied for deeper potential drilling. Time contour and depth contour map shows potential for deeper prospects. Also attribute analysis and 3d visualization show good results for deeper potential of Tobra and Khewar formations. Seismic amplitude, Reflection strength, Apparent polarity attribute are visualized and interpreted to find the potential for Tobra and Khewra formation. 3-D visualization also showed positive results for Tobra and Khewra formations.

3-D Geological Modeling-Concept,Methods and Key Techniques

3-D geological modeling plays an increasingly important role in Petroleum Geology, Mining Geology and Engineering Geology. The complexity of geological conditions requires different modeling methods in different situations. This paper summarizes the general concept of geological modeling; compares the characteristics of borehole-based modeling, cross-section based modeling and multi- source interactive modeling; analyses key techniques in 3-D geological modeling; and highlights the main difficulties and directions of future studies.

A study on 3-D velocity structure of crust and upper mantle in Sichuan -Yunnan region, China

Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others show the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the SichuanYunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the India and the Asia plates. The crustal velocity in the SichuanYunnan rhombic block generally shows normal value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below.

Scattering of seismic waves by three-dimensional large-scale hill topography simulated by a fast parallel IBEM

To solve seismic wave scattering by a large-scale three-dimensional(3-D) hill topography, a fast parallel indirect boundary element method(IBEM) is developed by proposing a new construction method for the wave field, modifying the generalized minimum residual(GMRES) algorithm and constructing an Open MP plus MPI parallel model. The validations of accuracy and efficiency show that this method can solve 3-D seismic response of a large-scale hill topography for broadband waves, and overcome the weakness of large storage and low efficiency of the traditional IBEM. Based on this new algorithm architecture, taking the broadband scattering of plane SV waves by a large-scale Gaussian-shaped hill of thousands-meters height as an example, the influence of several important parameters is investigated, including the incident frequency, the incident angle and the height-width and length-width ratio of the hill. The numerical results illustrate that the amplification effect on the ground motion by a near-hemispherical hill is more significant than the narrow hill. For low-frequency waves, the scattering effect of the higher hill is more pronounced, and there is only a single peak near the top of the hill. However, for high-frequency waves, rapid spatial variation of displacement amplitude appears on the hill surface.

Structural Interpretation and Petrophysical Analysis for Reservoir Sand of Lower Goru, Miano Area, Central Indus Basin, Pakistan

The main purpose of this research is to estimate the structural analysis and hydrocarbon potential of Miano Block by using seismic and well log techniques. Miano area hosts a number of gas fields with structural and stratigraphic traps. The area is located in Central Indus Basin which is a part of an extensional regime exhibiting normal faulting due to the split of the Indian Plate firstly from Africa and then from Madagascar and Seychelles. Miano area recognized as a proven petroleum province which has complex tectonic history of Cretaceous extensional and overprints of Tertiary strike-slip tectonics. The area has prospect with accumulation of hydrocarbons in structural and stratigraphic traps including pinchouts. NW-SE oriented Khairpur and Mari Highs are main structural features with impact on the fault system. The sands of Lower Goru of Lower Cretaceous age are acting as a reservoir in the area. The area has great potential of hydrocarbons for which more exploratory wells are required to be drilled with better insight of structural and stratigraphic traps.

Determination of 3-D Velocity Anomalies of the Nanbei Tectonic Zone of China Based on Local Earthquakes

In this paper, 3-D velocity images of the crust and upper mantle beneath the Nanbei tectonic zone of China are constructed using P-wave travel time residuals of earthquakes, with the data supplied by China's seismic networks and the International Seismic Centre.

3-D Modelling of the Confederation Bridge Using Data of Full Scale Tests

Long-span bridges are special structures that require advanced analysis techniques to examine their performance. This paper presents a procedure developed to model the Confederation Bridge using 3-D beam elements. The model was validated using the data collected before the opening of the bridge to the public. The bridge was instrumented to conduct fullscale static and dynamic tests. The static tests were to measure the deflection of the bridge pier while the dynamic tests to measure the free vibrations of the pier due to a sudden release of the static load. Confederation Bridge is one of the longest reinforced concrete bridges in the world. It connects the province of Prince Edward Island and the province of New Brunswick in Canada. Due to its strategic location and vital role as a transportation link between these two provinces, it was designed using higher safety factors than those for typical highway bridges. After validating the present numerical model, a procedure was developed to evaluate the performance of similar bridges subjected to traffic and seismic loads. It is of interest to note that the foundation stiffness and the modulus of elasticity of the concrete have significant effects on the structural responses of the Confederation Bridge.

鄂尔多斯盆地陕231井区盒_8储层预测

陕 2 31井区三维地震勘探是鄂尔多斯盆地的第一块大面积三维地震区块 ,部署的主要目的是准确地描述盒 8砂岩储层 ,提供水平井的钻探井位。本文在综合分析研究区地质、钻井、测井、地震资料的基础上 ,采用精细的构造解释技术及属性分析、地震相分析、地震反演等多种方法综合的储层预测技术 ,对该区的构造及储层做出精确的解释与预测 ,提出水平井的建议井位 ,为下一步天然气的开发提供了可靠依据。

Deep seismic sounding investigation into the deep structure of the magma system in Changbaishan-Tianchi volcanic region

The magma system of Changbaishan-Tianchi Volcanic region is studied with three-dimensional deep seismic sounding (DSS) technique. The results show that the magma system of Changbaishan-Tianchi volcanic region, mainly characterized by low velocity of P wave, can be divided into three parts in terms of depth. At the depth range of 9-15 km, the distribution of the magma system is characterized by extensiveness, large scale and near-SN orientation. This layer is the major place for magma storage. From the depth of 15 km down to the lower crust, it is characterized by small lateral scale, which indicates the 'trace' of magma intrusion from the upper mantle into the crust and also implies that the magma system most probably extends to the upper mantle, or even deeper.(less than 8-9 km deep), the range of magma distribution is even smaller, centering on an SN-oriented area just north of the Tianchi crater. If low velocity of P wave is related to the magma system, it then reflects that the magma here is still in a state of relatively high temperature. In this sense, the magma system of Changbaishan-Tianchi volcanic region is at least not 'remains', in other words, it is in an 'active' state.

Tectonic characteristics and structural styles of a continental rifted basin:Revelation from deep seismic reflection profiles

The Fushan Depression is a half-graben rifted sub-basin located in the southeast of the Beibuwan Basin, South China Sea. The Paleogene Liushagang sequence is the main hydrocarbon-bearing stratigraphic unit in the sub-basin. Using three-dimensional（3-D）seismic data and logging data over the sub-basin, we analyzed structural styles and sedimentary characteristics of the Liushagang sequence. Five types of structural styles were defined： ancient horst, traditional slope, flexure slope-break, faulted slope-break and multiple-stage faults slope, and interpretations for positions, background and development formations of each structural style were discussed. Structural framework across the sub-basin reveals that the most remarkable tectonic setting is represented by the central transfer zone（CTZ） which divides the sub-basin into two independent depressions, and two kinds of sequence architectures are summarized：（i） the western multi-stage faults slope;（ii） the eastern flexure slope break belt. Combined with regional stress field of the Fushan Depression, we got plane combinations of the faults, and finally built up plan distribution maps of structural system for main sequence. Also, we discussed the controlling factors mainly focused on subsidence history and background tectonic activities such as volcanic activity and earthquakes. The analysis of structural styles and tectonic evolution provides strong theoretical support for future prospecting in the Fushan subbasin and other similar rifted basins of the Beibuwan Basin in South China Sea.

3-D Seismic Identification and Characterization of Ancient Channel Morphology

It is easy to identify ancient fluvial morphologic types by the outcrop,log and core data.However,the horizontal distribution and geometry of the channels can only be identified and predicted by relying on the 3-D seismic data.The 3-D seismic horizon slices,especially,can play an important role in the sandstone prediction of meandering rivers,distributary channels and low-sinuosity channels.Every microfacies unit,including main channels,such as sinuous or branching channels,levee,crevasse channels,ligule crevasse splay and floodplain etc.can be identified.Braided channel sandstones are planar tabular lateral-connected sandbodies and the distribution of thick main channel belts can only be identified from 3-D seismic data.As the braided sandstones are ubiquitous,their occurrence and distribution do not need to be predicted.Generally,the coal velocity is so low that it can create a strong amplitude reflection in coal strata.It consequently conceals the amplitude respondence to anastomosing channel sandstone which could be identified from 3-D seismic inversion data sometimes.Case studies of mud-rich low-sinuosity rivers identified with 3-D seismic data indicate that the scales and width-to-thickness ratio of such sandbodies are small,laterally unconnected,and generally occurred on distant or further parts of an alluvial fan under dry climate conditions.Sometimes extraction of seismic attributes of every reflection event along horizons is expected to maximize expression of the spatial evolutions of ancient channels.

A Preconditioned 3-DMulti-Region Fast Multipole Solver for Seismic Wave Propagation in Complex Geometries

The analysis of seismic wave propagation and amplification in complex geological structures requires efficient numerical methods.In this article,following up on recent studies devoted to the formulation,implementation and evaluation of 3-D single-and multi-region elastodynamic fast multipole boundary element methods(FM-BEMs),a simple preconditioning strategy is proposed.Its efficiency is demonstrated on both the single-andmulti-region versions using benchmark examples(scattering of plane waves by canyons and basins).Finally,the preconditioned FM-BEM is applied to the scattering of plane seismic waves in an actual configuration(alpine basin of Grenoble,France),for which the high velocity contrast is seen to significantly affect the overall efficiency of the multi-region FM-BEM.

基于反射层的变层速度模型时深转换方法

基于反射波法的地震勘探技术是在时间域中认识地下地质情况的 ,由于地震波传播速度场的变化 ,反射成像和地下地质体间并非是一个简单的镜像对称关系 ,而是一种变异的镜像结果。要正确的认识地下地质体 ,必须把时间域中的地震数据恢复到深度域中。在断裂发育的断块区或复杂的逆掩构造区 ,由于断层错动及地层褶皱等因素 ,具有不同速度特征的地层在断层处相互接触或同一套地层多次重复。在这些地方地下空间速度场在短距离内会产生很大的变化 ,速度场变得相当复杂 ,准确的时深转换成为一件非常困难的事情。文章以反射层、断层面等时间域中的地质边界为约束条件 ,以钻井资料建立基础速度结构 ,采用“基于反射层的变层速度模型结构建立时深转换速度场”方法 ,实现精确时深转换。该方法应用灵活、建场方式直观 。

塔河油田典型地震相

奥陶系—三叠系是塔河油田的勘探目的层,寒武系—奥陶系的原油沿断裂进入以上各时代的储层中,形成构造、岩性、地层及各种复合油气藏。综合分析三维地震资料与测井、岩心等资料,识别和预测各种沉积相所控制的砂岩和岩溶储层空间展布规律成为塔河油田油气勘探与开发中的一项重要技术。在该区共识别和确定了三叠系的辫状河、曲流河典型地震相,石炭系卡拉沙依组的低弯度河和巴楚组的潟湖—障壁相,泥盆系的三角洲相及奥陶系的岩溶相共六种地震相。三维地震资料的沿层振幅切片、反射强度斜率、波形分类、测井曲线是了解沉积体系格架、骨架砂体和储层展布的主要手段。

高精度三维地震在泌阳凹陷北部复杂断块群勘探中的应用

泌阳凹陷北部斜坡带构造破碎,圈闭面积小,油藏埋深70～1200 m.为了得到断层和地质层位信息齐全的地震资料,从采集、处理和解释等方面进行了探讨。设计了基于模型的三维地震观测系统.采用新工艺解决了古河道和河床区激发接收条件差的问题,采用小道距、小线距、小偏移距和小炮线距技术解决了大规模障碍区浅层信息不全的问题;采用精细速度分析和叠前时间偏移等技术.提高了成像精度.剖面上断层清楚、信息丰富;采用三维可视化、面块切片和相干体分析等技术,搞清了断裂系统和断层的空间展布;采用综合评价技术,评价了有利含油气圈闭。通过以上技术的应用,目的层主频由原来的35 Hz提高到70～80 Hz.分辨出10 m左右的断层和单砂层.发现和落实了面积大于0.05 km2的小断鼻、断块和地层不整合圈闭.部署了15口预探井.有13口井钻遇油层。

塔中Ⅰ号坡折带奥陶系凝析气田勘探中的古地貌学方法

针对塔中地区碳酸盐岩埋藏深度大、横向非均质性强、岩层顶面地震反射强而内幕地震反射弱且分辨率低等地震地质特点,充分利用三维地震信息,精细解释了上奥陶统桑塔木组内部地震反射强振幅、强连续等时界面和碳酸盐岩顶界面,刻画了塔中Ⅰ号坡折带奥陶系碳酸盐岩台地—陆棚边缘高能礁滩体的地貌学特征,建立了碳酸盐岩建隆的地震地质模式。该模式为全面认识该区碳酸盐岩建隆沉积体系的发育特征和分布范围提供了重要依据,并在该区奥陶系凝析气田勘探、有利勘探区带评价和储量评估中得到了成功应用,取得了良好的经济效益。

高分辨率三维地震技术在油田开发中的应用

针对松辽盆地北部砂泥岩薄互层的地质特点 ,结合三维地震和高分辨率地震的优势 ,开展了高分辨率三维地震的研究工作。采集上在确保资料信噪比的前提下拓宽有效频带 ;处理上实现了在高信噪比基础上的高分辨率处理 ,使得地震资料在纵向和三度空间上能够更准确可靠地反映地下地质情况。地震解释采用先进的全三维构造精细解释和多信息多方法的综合地震岩性解释技术 ,提高了小断层、小幅度构造和储层预测的精度 ,经开发井验证 ,取得了较好的地质效果和经济效益。

龙门山中段山前彭县隐伏活动断裂三维构造特征

彭县隐伏断裂是龙门山中段山前的一条典型活动断裂,其构造特征对认识龙门山构造带向四川盆地生长的方式和过程具有重要的参考价值,但因其被四川盆地晚新生代较厚地层所覆盖,该断裂的构造样式、三维空间展布、形成机制以及发震能力等问题尚不明确。文中利用多条高精度三维地震反射剖面,结合区域地质与钻井资料,对彭县隐伏断裂的几何结构进行综合分析,建立了三维断层模型;同时根据断层相关褶皱与褶皱调节断层原理,对彭县隐伏构造的形成机制进行了探讨。研究结果表明,龙门山山前的浅层构造变形与中下三叠统的滑脱层f 1密切相关。该滑脱层一直向E延伸至四川盆地西部的龙泉山,彭县隐伏背斜为该滑脱层f 1之上的低角度断层转折褶皱,彭县隐伏断裂则发育在彭县隐伏背斜膝折带的前翼,是一条高角度(50°~60°)的逆断裂,走向NE-SW,总长约50km;彭县隐伏断裂与龙门山南段大邑隐伏断裂并不相连,非同一条断裂。彭县隐伏断裂与彭县隐伏背斜褶皱轴的走向一致且断距较小,该断裂的形成与背斜前翼褶皱变形有关,分析认为是一条褶皱调节性断层。文中系统地揭示了彭县隐伏活动断裂的几何学和运动学特征,对进一步分析断层活动性和危险性提供了依据。

用可视化技术分析虚拟现实环境下三维地震数据场的研究

目的 用可视化方法分析三维地震数据,直接观察数据中隐藏的地质现象。方法:将每个反射子波用一个粒子模型表示,来自同一反射面的子波粒子相互叠合成一个同相面。为加快显示速度,将一个三维地震数据体转换为三维二值图像,用有序扩展算法追踪同相面所在的三维连通域,细化后得到反射面的坐标数据。再在虚拟现实系统下对反射面进行立体显示,直观地分析地下地层的结构。结果 实际数据试验得到了反射面的三维形态及断层的分布规律,立体显示更深刻地揭示了复杂地质现象及其规律。结论 只有在虚拟现实系统中进行三维地震数据的可视化,才能直观地看到地下地层的真实场景,真正实现三维数据的全三维解释,所提出的方法是有效的。。