三维地震解释技术及其在苏北盆地溱潼凹陷的应用

反射地震剖面是进行精准油气勘探的手段之一,对勘探目标的精确定位,要求不断提高和发展三维地震资料解释技术.本文以苏北盆地溱潼凹陷的地震解释为例,验证了切片、方差体检测、正演模型、三维可视化及平衡剖面等地震解释技术组合的效果.解释成果刻画出溱潼凹陷古近系是由上、下两个构造层序叠合的、复式层序地层格架,由北向南可划分出北部缓斜坡带、中央深洼带、南部断坡带等沉积古地理单元,为有利油气聚集相带的预测奠定了坚实的基础.     

石臼坨凸起新近系岩性圈闭识别与刻画关键技术

规模性的区域岩性勘探要求高精度、高时效的岩性圈闭识别与刻画.对石臼坨凸起新近系明下段进行层序地层划分,建立层序地层格架,分析体系域内沉积砂体的发育规律,明确砂体的地质-地球物理响应关系.在此基础上,提出了适用于凸起区的岩性圈闭识别与刻画配套技术:基于地震属性提取的定性识别技术和基于地震多属反演的定量评价技术,实现了层序格架下岩性圈闭的快速、精细刻画.经钻井证实,该技术系列在凸起区滚动勘探中取得了很好的应用效果,钻探地质成功率达到100%,再发现一个新的亿吨级油田.     

OpendTect系统在层序地层研究中的应用

在等时层序格架建立的基础上,利用地震资料研究各体系域内部沉积体的空间展布、叠置样式和沉积演化过程,进而预测各体系域中砂体的分布,是层序地层学应用于勘探实践的重要内容.OpendTect系统在三维地震倾角扫描的基础上,①以地震采样点空间信息为导向,实现了层序界面控制下的地震小层自动追踪,可以精细刻画出体系域内部沉积体地震反射结构和空间展布;②通过对各层序单元内部地震小层追踪结果进行层拉平,实现了时间域到Wheeler域的自动变换,可以更加直观地分析地层沉积演化历史;③通过沿沉积体内部小层面提取地震属性,实现了等时地层切片的提取,减少了地震属性多解性,提高了预测精度.OpendTect系统提供了一种新的基于层序地层的地震综合解释技术和思路.     

南美前陆盆地隐蔽油气藏勘探

针对南美西北部前陆盆地斜坡带低幅度构造-岩性复合圈闭隐蔽性强、识别难度大、油藏边界难以准确描述等技术难点,开展了围绕油气藏特征及分布规律、层序地层及沉积微相、地震资料精细处理和解释的综合勘探方法研究.在厄瓜多尔奥连特盆地的研究成功指导了中方区块的勘探实践,并在开发区加密井的优选和部署中发挥了关键作用.形成了一套适用于南美前陆盆地斜坡带复合型隐蔽油气藏的勘探方法和识别技术.     

陇东黄土塬地区中生界石油砂岩储层预测

在鄂尔多斯盆地陇东黄土源地区地震解释中,采用广义S变换地震层序处理解释技术、三叠系顶部古地貌解释技术,以及各种储层横向预测技术,对比分析了应用效果。研究表明,用广义S变换地层层序处理解释技术可识别出约6m的层序界面,进而确认了陇东地区长8段砂体的展布方向,扩大了陇东地区西峰油田的勘探范围。     

基于随机介质建模的生物礁储层评价方法探讨——以南海L盆地生物礁为例

南海L盆地深水区,不仅有新近系生物礁发育的良好环境,更有生物礁油气藏形成的优越条件,是未来深水区勘探的重要领域.在生物礁储层评价、油气预测研究中,由于研究对象多为孔缝洞发育的细微储层结构,常规地震勘探多基于理想均匀介质或层状介质来研究储层结构,这显然容易忽略实际生物礁储层的局部非均质性对地震波响应特征和传播规律影响.本文以L盆地生物礁为例,在层序地层划分及沉积相分析双重约束下利用相对阻抗反演技术有效建立了生物礁储层框架模型,采用孔洞随机介质模拟技术对储层内部孔洞裂缝进行精细雕刻,建立能精细描述生物礁储层内强非均质性及孔缝洞物性特征的随机介质模型.最后通过正演模拟,定量地分析了盆地内生物礁储层的物性特征,从而进一步明确了盆地内寻找优质储层的方向,为勘探目标的寻找与优选提供科学的理论指导.     

惠民凹陷沙三段岩性油藏勘探中地震技术的应用

针对惠民凹陷岩性油藏勘探存在的难题,开展了岩性油藏勘探技术研究。以地震、地质资料为基础,采用井震联合及小波变换技术,完善了层序地层等时格架建立方法,确定了各三角洲的时空展布规律。应用多元综合标定、地震相划分、正演模拟和测井约束反演一系列技术,实现了不同沉积类型有利砂体的描述。形成了适合惠民凹陷沙三段岩性油藏勘探的技术系列,可以指导惠民凹陷沙三段岩性油藏的勘探。     

浊积岩分序级描述技术及其在东营凹陷油气勘探中的应用

浊积岩分序级描述技术是在前人研究与勘探实践基础上,以层序地层学理论为指导,结合较为前沿的地震沉积学理论,分析层序内部结构,明确了浊积岩发育序级的划分原则、对比和划分方法;以地震资料为基础,充分发挥了井震结合的优势,形成了浊积岩的地震识别模式的建立方法.本次研究建立了东营凹陷沙三段和沙四上不同类型浊积岩的地震响应模式,形成了浊积岩分序级描述技术;该技术可以用来预测新的浊积岩发育区.东营凹陷油气勘探实践证明,在浊积岩分序级描述的基础上进行勘探优化部署,可以有效的提高浊积岩油藏的勘探成功率.     

基于时频电磁法的富有机质页岩层系勘探研究

我国地质条件复杂、多样,能否充分发挥出非地震勘探技术成本低、效率高的技术优势,检验电法勘探技术在页岩气勘探中的有效性,是当前在页岩气勘探起步阶段亟待解决的重要问题之一.本文介绍了在研究和总结含气页岩密度、极化率、电阻率等岩石物理特征基础上,在四川盆地南部筠连地区开展的物性调查、时频电磁法勘探试验工作.勘探研究结果表明,本地区分布的富有机质页岩层系-志留系龙马溪组(S1l)具备开展电法勘探工作的物性条件,时频电磁法具有勘探富有机质页岩层系的能力.     

地震勘探信号时频分析方法对比与应用分析

针对地震勘探信号,对非平稳信号时频分析几种适效方法:短时Fourier变换、小波变换、S变换、Wigner分布、平滑伪Wigner分布、锥形核时频分布、AOK(adaptive optimum kernel,自适应最优核函数)分布等进行对比与应用研究.在阐明各种方法基本原理的基础上,进行数值分析与应用研究.首先对非平稳地震勘探模拟信号进行试算及时频属性提取,结合各类方法的信号表示理论,在时频局部化的精度和交叉项抑制等方面对计算结果进行对比分析;进一步应用于实际二维地震数据,提取瞬时频率和瞬时带宽等时频属性,进行比较研究.研究表明:对于地震勘探信号,就本文涉及的几种时频分析方法而言,AOK分布是时频局部化精度最高、交叉项抑制最好、时频匹配最优的方法,值得在地震勘探信号分析和地震属性提取、频谱分解等应用中深入研究和应用.     

地震时频分析与分频解释及频谱分解技术在地震沉积学与储层成像中的应用

基于非平稳信号时频分析及其地震时频属性技术应用的有关研究成果,对地震信号时频分析、分频解释与频谱分解及其在地震沉积学与地震储层成像中的应用进行系统总结与阐述.从时频分析的基本原理出发,探讨地震分频解释和频谱分解的实现方法及其在地震沉积学与储层成像中的应用策略与效果.分析指出,发展高精度时频分析理论和算法,一体化统筹谋划地震资料叠前与叠后处理解释,针对不同地质条件探索相应的时频响应规律等,是分频解释技术及其在地震沉积学和地震储层成像研究中有效应用中值得深入研究的问题.     

Quantitative integration of 3D and 4D seismic impedance into reservoir simulation model updating in the Norne Field

The ultimate goal of reservoir simulation in reservoir surveillance technology is to estimate long-term production forecasting and to plan development and management of petroleum fields. However, maintaining reliable reservoir models which honour available static and dynamic data, involve inherent risks due to the uncertainties in space and time of the distribution of hydrocarbons inside reservoirs. Recent applications have shown that these uncertainties can be reduced by quantitative integration of seismic data into the reservoir modelling workflows to identify which areas and reservoir attributes of the model should be updated. This work aims using seismic data to reduce ambiguity in calibrating reservoir flow simulation model with an uncertain petro-elastic model, proposing a circular workflow of inverted seismic impedance (3D and 4D) and engineering studies, with emphasis on the interface between static and dynamic models. The main contribution is to develop an updating procedure for adjusting reservoir simulation response before using it in the production forecasting and enhance the interpretive capability of reservoir properties. Accordingly, the workflow evaluates consistency of reservoir simulation model and inverted seismic impedance, assisted by production history data, to close the loop between reservoir engineering and seismic domains. The methodology is evaluated in a complex, faulted, sandstone reservoir, the Norne benchmark field, where a significant reservoir behaviour understanding (about the static and dynamic reservoir properties) is obtained towards the quantitative integration of seismic impedance data. This leads to diagnosis of the reservoir flow simulation reliability and generation of an updated simulation model consistent with observed seismic and well production history data, as well as a calibrated petro-elastic model. Furthermore, as Norne Field is a benchmark case, this study can be considered to enrich the discussions over deterministic or probabilistic history matching studies.     

频谱成像技术研究进展

频谱成像技术是近年来发展起来的一项基于频率谱分解的储层特色解释技术,是地震属性分析中重要组成部分.频谱成像技术具有在空间横向上分辨率高的特点,是一种利用三维地震资料的多尺度信息对储层进行高分辨率成像、检测储层时间厚度变化的工具.地震数据振幅谱可以识别地层的时间厚度变化,相位谱可以检测地质体横向不连续性,在确定油藏边界、计算地层厚度方面比传统地震属性研究方法具有更大的优势.频谱成像技术的核心模块是信号的时频分析,本文回顾了频谱成像技术的基本概念和目前在频谱成像中广泛应用的时频分析方法,简单介绍了几种新的时频分析方法:广义S变换和改进的匹配追踪算法.     

地震低频伴影的数值模拟与应用

Strong low-frequency energy beneath a hydrocarbon reservoir is called a seismic low-frequency shadow and can be used as a hydrocarbon indicator （Tarter et al., 1979） bu the physical mechanism of the observed low-frequency shadow is still unclear. To stud） the mechanism, we performed seismic numerical simulation of geological models with a hydrocarbon-bearing zone using the 2-D diffusive-viscous wave equation which car effectively model the characteristics of velocity dispersion and transform the seismic dat~ centered in a target layer slice within a time window to the time-frequency domain by usinl time-frequency signal analysis and sort the frequency gathers to common frequency cubes. Then, we observe the characteristics of the seismic low-frequency shadow in the common frequency cubes. The numerical simulations reveal that the main mechanism of seismic lowfrequency shadows is attributed to high attenuation of the medium to high seismic frequency components caused by absorption in the hydrocarbon-filled reservoir. Results from a practical example of seismic low-frequency shadows show that it is possible to identify the reservoir by the low-frequency shadow with high S/N seismic data.     

紫坪铺水库诱发地震与构造地震波谱时频特征差异性研究

利用紫坪铺水库2004～2007年记录的实际地震数据,通过比较多种滤波方法,发展出一种既能有效滤除地震数据中本底噪音、又对有效信号损伤较小的比值滤波方法。对去噪后的水库诱发地震和构造地震数据,利用小波变换方法,分别进行时频分析获得两类地震的时频谱,并提取可以反映地震发生前后能量分布和聚集情况的时频属性,最后根据各个属性的响应效果,组合得到新的属性。将时频谱与时频属性相结合,总结归纳紫坪铺水库诱发地震与构造地震波谱时频特征的差异性,为地震监测分析提供基础依据。     

叠前反演和地震吸收技术在复杂天然气藏地震预测中的应用

针对某复杂断块天然气目标储层,在岩石物理分析的指导下,综合利用地质、地震、测井等资料,提出了一套面向复杂天然气藏的叠前地震预测技术.首先基于地震岩石物理分析得到的初始横波信息,采用叠前贝叶斯非线性三参数反演得到了井旁控制点处精确纵横波速度和密度信息,然后通过叠前/叠后联合反演技术实现了面向目标的弹性阻抗体反演及含气储层敏感参数直接提取,最后结合小波变换时频谱分析的方法从叠前地震资料中估算地层吸收参数值,提高天然气藏识别精度.实际应用表明,综合各种叠前地震预测技术,可以大大提高对复杂天然气藏的识别精度,降低勘探风险.     

Intra-survey reservoir fluctuations – implications for quantitative 4D seismic analysis

During the time taken for seismic data to be acquired, reservoir pressure may fluctuate as a consequence of field production and operational procedures and fluid fronts may move significantly. These variations prevent accurate quantitative measurement of the reservoir change using 4D seismic data. Modelling studies on the Norne field simulation model using acquisition data from ocean-bottom seismometer and towed streamer systems indicate that the pre-stack intra-survey reservoir fluctuations are important and cannot be neglected. Similarly, the time-lapse seismic image in the post-stack domain does not represent a difference between two states of the reservoir at a unique base and monitor time, but is a mixed version of reality that depends on the sequence and timing of seismic shooting. The outcome is a lack of accuracy in the measurement of reservoir changes using the resulting processed and stacked 4D seismic data. Even for perfect spatial repeatability between surveys, a spatially variant noise floor is still anticipated to remain. For our particular North Sea acquisition data, we find that towed streamer data are more affected than the ocean-bottom seismometer data. We think that this may be typical for towed streamers due to their restricted aperture compared to ocean-bottom seismometer acquisitions, even for a favourable time sequence of shooting and spatial repeatability. Importantly, the pressure signals on the near and far offset stacks commonly used in quantitative 4D seismic inversion are found to be inconsistent due to the acquisition timestamp. Saturation changes at the boundaries of fluid fronts appear to show a similar inconsistency across sub-stacks. We recommend that 4D data are shot in a consistent manner to optimize aerial time coverage, and that additionally, the timestamp of the acquisition should be used to optimize pre-stack quantitative reservoir analysis.     

盐下特低孔渗碳酸盐岩油藏高产带地震预测方法研究

肯吉亚克油田石炭系油藏属持低孔渗、异常高压碳酸盐岩油藏，它除了具有埋深大，非均质性强，油气成藏控制因素复杂等特点外，其上还覆盖巨厚盐丘，造成盐下地震反射时间和振幅畸变严重，地震成像差、信噪比低和分辨率低，给储层预测工作带来极大困难。如何正确预测油藏高产带分布规律是高效开发这类油藏的关键，本文研究从分析形成碳酸盐岩油藏高产带的主控因素入手，通过井震标定，优选反映碳酸盐岩岩相、岩溶、物性和裂缝的地震属性，结合地震、地质、测井、油藏工程和钻井资料，把盐下特低孔渗碳酸盐岩油藏高产带预测问题分解成构造解释、岩相预测、岩溶预测、物性预测、裂缝预测和综合评价等六个环节。宏观上，通过建立断裂、岩相、岩溶模式，定性预测储层分布有利区带；微观上，通过多参数储层特征反演和多属性综合分析，定量、半定量预测有利储层分布，有效解决盐下碳酸盐岩油藏高产带预测难题，基本搞清本区碳酸盐岩油藏高产带分布规律，为优选有利勘探和开发目标提供依据。文中提出的方法和技术对解决国内外碳酸盐岩油藏高产带预测和其他复杂储层预测问题有借鉴作用。     

Analysis of reservoir heterogeneity-induced amplification effect on time-lapse seismic responses of fluid substitution: A physical modelling study

Seismic wave propagation through a fluid-saturated poroelastic layer might be strongly affected by media heterogeneities. Via incorporating controlled laboratory simulation experiments, we extend previous studies of time-lapse seismic effects to evaluate the wave scattering influence of the heterogeneous nature of porous permeable media and the associated amplification effects on 4D seismic response characteristics of reservoir fluid substitution. A physical model consisted of stratified thin layers of shale and porous sandstone reservoir with rock heterogeneities was built based on the geological data of a real hydrocarbon-saturated reservoir in Northeast China. Multi-surveys data of good quality were acquired by filling poroelastic reservoir layers with gas, water and oil in sequence. Experimental observations show that reservoir heterogeneity effect causes significantly magnified abnormal responses to the fluid-saturated media. Specifically, reflection signatures of the gas-filled reservoir are dramatically deviated from those of the liquid fluid-filled reservoir, compared with ones of the homogeneous media. By removing the influences unrelated to reservoir property alterations, 4D seismic estimates of travel-time and frequency-dependent characteristic are reasonably consistent with fluid variations. Nevertheless, strong 4D amplitude difference anomalies might not correspond to the regions where fluid variations occur. We also find that 4D seismic difference attributes are evident between oil- and water-filled models, whereas significant between oil- and gas-filled models. Meanwhile, rock physics modelling results reveal the predicted 4D seismic differences are obviously smaller than those calculated from seismic observations. The results in this paper, therefore, implicate that the effect of a reservoir's heterogeneous nature might be beneficial for hydrocarbons detection as well as monitoring small variations in pore fluids.     

Uncertainties in quantitative time-lapse seismic analysis

Most seismic time-lapse studies so far have been of a qualitative nature. Identification of areas with minor or no seismic changes has been used to plan new infill drilling targets. Increased accuracy in seismic acquisition methods, in both conventional streamer surveys and newer methods such as multicomponent sea-bed seismic and permanent sensors, opens possibilities for the next step: quantitative time-lapse analysis. Quantitative methods here mean the estimation of, for instance, a change in fluid saturation from 20% water to 90% water or the estimation of a pore pressure change of 5 MPa. Explicit expressions for the uncertainties associated with estimated changes in, for instance, reservoir pressure and fluid saturation are derived. These formulae can be used to compare relative uncertainties between estimated parameters as well as to identify the critical factors in various estimation techniques. The importance of accurate rock physics input, as well as that of highly repeatable time-lapse seismic data, is emphasized. Furthermore, uncertainty analysis can be used to find optimal weight factors when the same parameter (e.g. saturation change) is estimated by two or three different techniques.