井间地震技术在松南油气开发中的初步应用研究

为了研究松南地区陆相砂泥岩薄互层储层岩石物性横向变化、微构造等对油气聚集的影响和探索利用高分辨率井间地震技术直接指示油气分布的可能性,开展了井间地震及地面小三维地震、VSP、测井等立体地震观测．使用了自行研制的井中炸药震源和常规地震记录仪器．采用层析成像方法、反射资料叠前偏移成像方法等对采集到的资料进行研究,得到了不同分辨率的地下构造和岩石物性信息,展示出不同方法技术在分辨薄储层能力上的差异．高分辨率的井间地震成果较好地实现了井间地层对比,查清了两井间储层横向变化和油气分布情况．层析速度与构造信息等的综合应用解释了两井油气产能差异的原因,建立了油气地质模型．所得成果显示出井间地震技术在油气开发中的潜力．     

内蒙古准苏吉花钼矿及外围反射地震和层析成像探测

由于金属矿区地质构造的复杂性,地震反射方法在金属矿区的应用效果一般较差.为解决金属矿勘查中的方法技术问题,在内蒙古准苏吉花斑岩型钼矿床及其外围地区开展了地震层析成像和高精度反射地震联合勘探的方法技术研究.高精度反射地震采用2台套大功率可控震源激发,5m道间距,960道接收,80次水平叠加的工作方法;地震层析成像采用了1000道采集,10m道间距,9990m接收排列长度,采用炸药震源激发,炮间距约2500m,最小炮检距10m,最大炮检距10500m,采用排列中间或单边激发的相遇观测系统.两种探测方法均获得了能清晰反映深部地质结构和构造的反射地震和层析速度剖面.试验研究结果表明,地震层析成像不但可弥补反射地震资料在探测浅表层方面的不足,而且还可为反射地震资料偏移处理提供有用的速度信息,从而提高反射地震资料的处理效果;该联合勘探结果还为在该区寻找深部隐伏金属矿指明了新的找矿靶区.     

井间地震资料精细解释方法研究与应用

井间地震资料分辨率很高,但是缺乏成熟的解释方法,本文针对井间地震资料的特点,借鉴地面地震解释技术对井间地震资料开展了精细解释方法研究.首先在深度域资料特点分析的基础上,利用区域速度和层析成像速度将深度域井间地震资料转换到时间域进行研究,并通过粗化降频建立起井间地震资料与地面地震资料之间的相似性联系,得到对井间地震低频反射特征的认识,结合井旁道合成地震记录标定建立起井间地震资料的反射特征,准确的解释了井间地震的反射层位.采用地震瞬时属性分析和时频属性分析得到了对沉积环境的认识,进一步通过波阻抗反演更好的认识井间储层特征.在实际应用中综合多种方法进行解释,并结合测井资料对比落实了井间砂体展布特征,得到对井间储层的精细描述结果,解决了两口井之间储层分布范围、横向连通性及厚度变化等问题,取得了较好的应用效果.     

天然地震层析成像技术在油气勘探中的应用

天然地震层析成像技术,主要是利用布设地震台阵记录天然地震事件体波到时信息,通过反演得到研究区域的三维速度结构分布.全国油气资源战略选区调查与评价项目在柴达木盆地西部复杂地区进行的天然地震层析成像试验结果表明,根据层析成像结果所推断的构造分布与其它方法的勘探结果相比具有一定的相似性,波速异常与测井得到的岩性特征有较好的对...     

井间地震资料测井约束层析成像

利用井间地震资料进行层析成像,由于受观测角的限制,其成像过程具有很强的不稳定性.为了提高成像过程的稳定性,本文将测井资料引入到反演过程中,利用测井资料约束井间地震反演成像过程.采用假设模型进行数值模拟和反演实验,并与无约束反演方法进行对比实验,多种反演结果对比表明,测井约束反演方法改善了层析成像过程的稳定性,提高了成像结果的精度.     

横向非一致地震激励下埋地管道的动力响应分析

为研究埋地管道在地震激励时管-土相互作用的动力响应问题,研发双向层状剪切连续体模型土箱,建立管G土相互作用有限元分析模型,对横向非一致地震激励下埋地管道地震响应进行数值模拟分析,并与试验结果进行对比.结果表明:数值模拟和振动台试验结果中的管道应变峰值均呈现出沿管道中间大两端小的现象,管道中间应变峰值最小达到两端的1．6倍左右;管道加速度、 土体加速度峰值均随着加载等级的提高而增大,涨幅愈加明显,多峰频率由0~10Hz逐渐向10~ 20Hz频域扩散,管道运动更为自由;土体位移随着加载等级的提高呈现逐级增大的现象,在加载等级增加到0．4g 时位移曲线斜率减小,土体非线性表现明显.数值模拟和振动台试验对比分析的结论表明数值模拟分析的合理性和试验结果的可靠性,为研究横向非一致激励对埋地管道地震响应的影响提供了依据.     

利用井间地震层析成像方法探测隐伏断层

针对目前隐伏断层探测中存在的技术难题,提出了在地面反射地震勘探初步确定的断点附近,用井间地震层析成像方法探测隐伏断层及其上断点的埋深。首先介绍井间地震技术的应用现状和井间地震层析成像的基本原理,并结合实例讨论了井间初至走时层析成像的野外数据采集和室内资料处理方法。芦花台隐伏断层的井间地震层析成像结果表明,采用弯曲射线追踪方法反演得到的跨芦花台隐伏断层的井间纵波速度结构图像与钻孔联合剖面揭示的断层特征相吻合。      

矿井电阻率成像技术的现状与展望

主要介绍国内外关于矿井电阻率层析成像技术在矿井生产中应用的相关资料,综合论述了矿井电阻率成像技术发展现状,介绍了矿井电阻率层析成像技术的特殊问题、井下勘探主要方法和数值模拟技术,并提出了作者对矿井电阻率成像技术发展趋势的展望．     

挡土墙地震反应非线性波动模拟

本文运用解耦近场非线性波动数值模拟方法研究挡土墙地震反应，为反映墙土体系在地震作用下的位移机制，引入了Desai薄层单元模拟墙土间接触面，并采用双线型本构关系作为接触面单元和土体的非线性模型，在此基础上给出了解决P—SV问题的非线性显式有限元时域递推公式，为进一步发展非线性波动数值模拟技术提供了有益经验。为验证本文方法及适用性，将数值模拟结果与Zeng，X．和Madabhushi，X．P．G．等的离心机试验和弹塑性数值模拟结果进行对比。结果表明：墙土体系加速度、挡土墙顶底相对滑移、沉降和墙体倾角等同离心机试验模拟结果基本吻合，与弹塑性数值模拟结果相似。     

地壳测深的地震数据的收集与处理方法的最新进展

地壳测深的地震数据的收集与处理方法的最新进展５．１宽角地震数据方法与结果５．１．１用宽角地震数据进行速度和界面的同时成像由于技术的进步，海洋宽角地震数据现在可以用类似于常规反射测量的炮点密度进行采集。数据的大量增加超过了现有的正向模拟方法的能力。英国...     

高分辨折射和浅层反射地震方法在活断层探测中的联合应用

浅层反射地震方法是城市活断层探测常用的技术,但在基岩埋深比较浅的地区,往往只能识别出基岩顶面的反射波,而仅根据反射地震剖面上单个同相轴的变化很难准确判定断层是否存在.浅层地层的错断往往会引起速度的横向变化,利用高分辨折射地震方法采集的数据,应用层析成像方法获得的速度剖面,能够反映地下速度结构的变化,可以从另一方面揭示浅层断层存在的可能性.在四川某地,将这两种方法同时应用于活断层浅层地震勘探中.结果表明,两种方法联合应用可在一定程度上弥补浅层反射地震勘探方法在基岩埋深较浅地区的不足.     

A METHOD TO DETERMINE THE VELOCITIES OF THE SEAFLOOR AND NEAR-SURFACE SEDIMENTS*

Shotpoint gathers from conventional reflection seismic surveys contain both reflected and refracted waves. In this study shot records were processed and analyzed, and the data were modeled with reflected, refracted, and reflected-refracted waves to fit the recorded data. The result is a detailed velocity model. The inverse problem for refracted waves was solved by using the Wiechert-Herglotz inversion. A 500-km-long 26-fold reflection seismic line from the Barents Sea, north of Norway, has been investigated. The data show high velocities, multiple reflections, and various types of noise. To test the method a total of 34 shot gathers were analyzed along this line. The aim of the interpretation was to determine the velocity in the seafloor and the near-surface sediments. It is possible to map the vertical as well as the lateral velocity distribution in detail. Depending on the length of the streamer and the velocity gradient in the sediments, the calculated depth varies between 300 and 500 m below the seafloor. These velocities were also compared to the stacking velocities obtained from the reflection seismic data to see how the velocities determined by different methods were related. The velocity distribution in the sediments is one of the key factors in seismic interpretation. The technique discussed in this paper can contribute to velocity information both in the processing and interpretation of seismic data.     

直接找油气的地球物理新原理的进展现状

近年来,国际上利用地震反射波勘探技术直接找油气的探索研究受到普遍重视.本文试图针对这一发展历史作一综述. 首先,介绍Knott（1899）和Zoeppritz（1919）分别导出的反射波振幅公式进行的数值计算,从而发现振幅与入射角的变化关系及其受反射面两侧岩层泊松比值的影响.然后,列举了几处油气区地震波勘探直接找油气的实例,以试验此项新原理在实践中所遇到的问题,说明直接找油气的地球物理新方法是可取的,是有前途的,但目前还不够有效,要达到实用还有一段较长的距离,因此,有进一步加强基础性实验研究的必要.     

再论地震数据偏移成像

利用地震波正向传播方程对属于波形线性反演问题近似求解方法的地震数据偏移成像进行重新推导,得到了适合散射地震数据的散射偏移成像方法和适合反射地震数据的反射偏移成像方法.以地震波传播的散射理论为出发点,首先根据描述一次散射波正向传播的线性方程研究建立散射地震数据的偏移成像方法理论;利用高频近似对产生散射波场的地下速度扰动函数的空间变化进行近似,推导出地下反射率函数,再由散射波传播方程推导出基于反射率函数的反射波传播方程,然后根据描述一次反射波正向传播的线性方程研究建立反射地震数据的偏移成像方法理论.本文指出和修正了Claerbout偏移成像方法中的不足,提出的地震数据偏移成像方法是对当前偏移成像方法理论的完善,使反射地震数据偏移成像具有了更坚实的数学物理理论基础,得到的偏移成像结果相位正确、位置准确、分辨率提高.     

由地震反射波剖面研究圣安德烈斯断层带的结构

1978年,在美国中加利福尼亚完成了一条横跨圣安德烈斯断层带的地震反射波剖面.由于断层带存在着强烈的侧向非均匀性和低速结构,观测结果极为复杂.这种断层带上的侧向速度急剧变化还有其它表征,诸如震中定位的偏移、地震节平面的变形等等.在这种情况下,处理反射波资料的常规计算与解释方法,已经难以实施.本文采用 May 和 Covey(1981)[11]的射线反演方法,根据其它地球物理资料建立初始模型,再利用真实振幅的迭加剖面,推断出其阻抗对比的分布,通过反复迭代反演,获得了速度模型.反演计算的非唯一性固然存在,但该结果与断层带地区的各种地球物理证据是一致的,并揭示了圣安德烈斯断层带的细致结构.      

Lithology-dependent seismic anisotropic amplitude variation with offset correction in transversely isotropic media

Analysis of amplitude variation with offset is an essential step for reservoir characterization. For an accurate reservoir characterization, the amplitude obtained with an isotropic assumption of the reservoir must be corrected for the anisotropic effects. The objective is seismic anisotropic amplitude correction in an effective medium, and, to this end, values and signs of anisotropic parameter differences (Δδ and Δε) across the reflection interfaces are needed. These parameters can be identified by seismic and well log data. A new technique for anisotropic amplitude correction was developed to modify amplitude changes in seismic data in transversely isotropic media with a vertical axis of symmetry. The results show that characteristics of pre-stack seismic data, that is, amplitude variation with offset gradient, can be potentially related to the sign of anisotropic parameter differences (Δδ and Δε) between two layers of the reflection boundary. The proposed methodology is designed to attain a proper fit between modelled and observed amplitude variation with offset responses, after anisotropic correction, for all possible lithofacies at the reservoir boundary. We first estimate anisotropic parameters, that is, δ and ε, away from the wells through Backus averaging of elastic properties resulted from the first pass of isotropic pre-stack seismic inversion, on input data with no amplitude correction. Next, we estimate the anisotropic parameter differences at reflection interfaces (values and signs of Δδ and Δε). We then generate seismic angle gather data after anisotropic amplitude correction using Rüger's equation for the P-P reflection coefficient. The second pass of isotropic pre-stack seismic inversion is then performed on the amplitude-corrected data, and elastic properties are estimated. Final outcome demonstrates how introduced methodology helps to reduce the uncertainty of elastic property prediction. Pre-stack seismic inversion on amplitude-corrected seismic data results in more accurate elastic property prediction than what can be obtained from non-corrected data. Moreover, a new anisotropy attribute (ν) is presented for improvement of lithology identification.     

地震海洋学研究进展

地震海洋学是利用反射地震方法探测海水温盐结构的一门新兴交叉学科．其主要优势在于水平方向的分辨率较高,能够弥补传统物理海洋学观测在时空尺度上的缺陷,为研究温盐结构、海洋动力过程提供了一种可视化手段．本文将追溯地震海洋学的发展历程,详细阐述近年在地震剖面和海水温盐结构的关系、内波、地中海涡旋、潜流等海洋学现象研究以及在海水温度结构反演、地震波模拟等定量研究方面的最新进展．最后展望地震海洋学今后的发展,阐述了未来可能取得突破的7个研究领域,如混合,内波的3D波包等．     

COMPUTING FIELD STATICS WITH THE HELP OF SEISMIC TOMOGRAPHY*

Field static corrections in general need be applied to all onshore seismic reflection data to eliminate the disturbing effects a weathering layer or near-surface low velocity zone has on the continuity of deep seismic reflections. The traveltimes of waves refracted at the bottom of the low velocity zone (or intermediate refracting interfaces) can often be observed as first breaks on shot records and used to develop a laterally inhomogeneous velocity model for this layer, from which the field static corrections can then be obtained. A simple method is described for computing accurate field statics from first breaks. It is based on a linearization principal for traveltimes and leads to the algorithms that are widely and successfully applied within the framework of seismic tomography. We refine an initial model for the low velocity layer (estimated by a standard traveltime inversion technique) by minimizing the errors between the observed first arrivals on field records and those computed by ray theory through an initial model of the low velocity layer. Thus, one can include more lateral velocity variations within the low velocity layers, which are important to obtain good field static corrections. Traditional first break traveltime inversion methods cannot, in general, provide such refined velocity values. The technique is successfully applied to seismic data from the Amazon Basin. It is based on a simple model for the low velocity layer that consists of an undulating earth surface and one planar horizontal refractor overlain by a laterally changing velocity field.     

AN ATTEMPT AT THE INVERSION OF REFLECTION DATA*

The main problem in seismic prospecting is to infer from the observed reflection response the distribution of density and seismic velocity with depth. This process is generally called the inversion of the reflection data. For plane waves propagating through plane parallel stratification, it can be shown that at any depth the ratio between the amplitude of the transmitted and reflected wave satisfies the Riccati equation. Based on this equation we have formulated an iterative inversion method, which is found to be suitable for numerical computations. We have applied this method on synthetic reflection data, and found that it provides a very fast and accurate inversion.     

Reflection point sideslip and smear in imaging below dipping anisotropic media

Dipping anisotropic clastic strata are ubiquitous in fold and thrust belts. Geological structures below these strata will be mispositioned laterally and vertically on seismic images if we do not properly correct for seismic anisotropy during migration. The magnitude of this lateral mispositioning of a target structure varies with source‐receiver offset, so reflection points will be smeared in the final stacked image. Raytracing demonstrates the lateral‐position and smear phenomena when imaging structures below tilted transversely isotropic media. Analysis of the raytracing results predicts the quantity of lateral‐position error and reflection‐point smear on a seismic image. We created numerical‐model seismic data to show reflection‐point smear on synthetic seismic images and to evaluate the accuracy of the predictions from raytracing.