共查询到19条相似文献，搜索用时 375 毫秒
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《地球物理学进展》2016,(2)
近年来,全球海上油气勘探热点逐渐由浅水走向深水,而地震资料采集和处理是制约深水油气勘探的重要因素.以往资料表明,受采集观测系统的影响,深水盆地陡坡带的地震成像效果往往较差,对边界断层和下伏地层产状的认识造成严重影响.本文根据巴布亚盆地某深水工区实际数据,构建典型深水陡坡带地质模型,通过地震波场正演模拟方法对陡坡带地震采集的观测方式进行优化.结合基于波动方程的单炮照明和多炮照明组合等地震照明方法对目标层进行照明分析,探索影响陡坡带深大断层和上、下盘地层成像效果的原因.最后通过局部炮集数据进行叠前深度偏移处理,进一步验证波场正演模拟和照明分析指导观测系统优化设计的有效性.波场正演模拟和照明分析结果表明,对于拖缆式地震采集,采用左侧激发、长排列接收方式对深水陡坡带成像具有相对较好的效果. 相似文献
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地震照明分析是地震数据采集和实际资料处理解释中的一种辅助手段,指在给定地下地质构造时,采用数值模拟的方法模拟出地震波在地下介质中的能量分布形态.自由表面相关多次波是海上地震数据中重要的波场信息,传统地震数据处理方法一直都将其视为干扰信息而进行去除,错失了很多有意义的构造信息.本文采用基于时间域有限差分法的双程波动方程进行波场数值模拟,将多次波能量考虑到波场照明中,通过单一透镜盐体模型试算表明,与传统一次波照明相比,多次波照明方法的波场信息更丰富、盐下构造照明更清晰、照明阴影区域更小.将多次波照明分析应用到Pluto速度模型,对比分析可以看出多次波照明分析方法更能适应复杂地质构造目标.通过多次波照明分析方法,我们能够对复杂地质构造的采集系统进行评价和优化,并预测地震偏移成像的质量. 相似文献
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基于正演模拟的观测系统优化是提高地震采集资料品质和降低采集成本的重要手段.在常规高斯射线束正演模拟理论的基础上,提出了基于菲涅尔带约束的高斯射线束(菲涅尔高斯束)正演模拟理论,相对于常规高斯射线束正演,菲涅尔高斯束在传播路径上由第一菲涅尔带约束,具有较小的有效半宽度,使得中心射线附近波场的走时和振幅计算更加准确.在中心射线终点处,提取目的层面元接收能量,建立能量均方差和平均能量分析函数,定量化分析评价不同观测系统下各目的层能量分布情况,预测后期偏移成像效果.基于目的层接收能量优化炮点加密方案,进而实现面向复杂地质目标的观测系统优化设计.该方法在胜利探区G94北区块应用,有效弥补了陡坡带上照明阴影区能量,改善了采集资料偏移成像效果. 相似文献
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地震照明分析是在给定地下背景结构的情况下用模拟方法研究采集系统对地下结构的探测能力.对目标照明的影响主要来自观测系统的设置,上覆地质结构的复杂性以及目标倾角等三项因素.我们将上述因素的影响统一纳入到对照明的定量计算中.本文阐述了关于地震照明的一系列基本概念,并基于波动理论给出对不同类型照明的计算方法.首先将入射和散射波分解到局部角度域并导出局部照明矩阵,它包括了在目标附近所有可能的入射和散射方向对照明的贡献.从照明矩阵出发,研究入射和反射波在角度域中与反射面的相互作用,并由此获得对地下结构的不同照明描述.作为例子,具体给出了对局部照明矩阵,空间体照明,反射面定向照明,反射面照明角度覆盖,以及对反射面可视性的计算方法,并给出了相应的数值计算结果. 最后,讨论了照明分析方法在地震采集设计中的一些可能应用. 相似文献
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斜缆采集是近些年发展起来的海上采集技术,主要为了压制虚反射,获得高品质的宽频地震资料。线形斜缆和弧形斜缆是目前最常用的斜缆类型,能够获取较多的高低频信息。针对这两种斜缆采集方式,通过对比不同采集参数的地震记录及其消除虚反射后的数据,发现弧形斜缆采集观测系统明显优于线形斜缆,不仅在波场模拟中表现出较好的特征,而且在虚反射消除的过程中,引入了较小的噪声,能够获得较高信噪比的地震资料。分析模型测试的结果,证明海上地震勘探中更适合采用弧形斜缆。 相似文献
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垂直缆地震法是海洋地震勘探学里新发展起来的一种具有潜在应用前景的观测技术。本文基于射线追踪理论,采用基于不规则单元的双线性走时插值和快速波前扩展的高精度和高效率方法,并以目标层反射点分布密度作为衡量观测系统的主要参数,通过一系列三维海底地层模型和炮点、垂直接收缆及其水听器布设的数值模拟实验,对海洋地震垂直缆观测系统进行照明分析,取得了垂直缆观测系统参数对目标层反射点分布的影响规律,为最佳垂直缆观测系统设计和提高地震成像质量提供参考依据。 相似文献
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海上非零偏VSP技术是一项在地震船井周放炮以实现变井源距激发、井筒中布设三分量检波器进行接收的井筒物探技术.本次试验采集是Walkaway和Walkaround VSP在中国近海海域深层气田的首次非零偏VSP联合试验,为改善海上深层常规拖缆三维地震资料品质提出了新的解决方案.东海盆地存在目的层埋藏深、构造复杂以及储层非均质性强等特殊地质条件,常规拖缆地震采集处理存在多次波发育、信噪比和分辨率低等问题.经过优选试验靶区,开展采集模拟设计,优化采集方式和采集参数等确定了观测系统,在东海深层开展了四个方向的Walkaway VSP以及两个不同半径环线的Walkaround VSP现场作业,通过精细处理获得了井周精细构造及储层信息.同时,利用非零偏地震资料求取衰减因子和多次波模型等相关地震参数,通过井控三维处理得到分辨率和信噪比增强的拖缆三维地震数据.实际应用及分析表明,该项井震结合技术可有效提高地震资料品质,对海上深层气田砂体追踪和气藏描述效果良好. 相似文献
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Directional‐oriented wavefield imaging: a new wave‐based subsurface illumination imaging condition for reverse time migration 
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下载免费PDF全文 The key objective of an imaging algorithm is to produce accurate and high‐resolution images of the subsurface geology. However, significant wavefield distortions occur due to wave propagation through complex structures and irregular acquisition geometries causing uneven wavefield illumination at the target. Therefore, conventional imaging conditions are unable to correctly compensate for variable illumination effects. We propose a generalised wave‐based imaging condition, which incorporates a weighting function based on energy illumination at each subsurface reflection and azimuth angles. Our proposed imaging kernel, named as the directional‐oriented wavefield imaging, compensates for illumination effects produced by possible surface obstructions during acquisition, sparse geometries employed in the field, and complex velocity models. An integral part of the directional‐oriented wavefield imaging condition is a methodology for applying down‐going/up‐going wavefield decomposition to both source and receiver extrapolated wavefields. This type of wavefield decomposition eliminates low‐frequency artefacts and scattering noise caused by the two‐way wave equation and can facilitate the robust estimation for energy fluxes of wavefields required for the seismic illumination analysis. Then, based on the estimation of the respective wavefield propagation vectors and associated directions, we evaluate the illumination energy for each subsurface location as a function of image depth point and subsurface azimuth and reflection angles. Thus, the final directional‐oriented wavefield imaging kernel is a cross‐correlation of the decomposed source and receiver wavefields weighted by the illuminated energy estimated at each depth location. The application of the directional‐oriented wavefield imaging condition can be employed during the generation of both depth‐stacked images and azimuth–reflection angle‐domain common image gathers. Numerical examples using synthetic and real data demonstrate that the new imaging condition can properly image complex wave paths and produce high‐fidelity depth sections. 相似文献
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In recent years, a variety of Marchenko methods for the attenuation of internal multiples has been developed. These methods have been extensively tested on two-dimensional synthetic data and applied to two-dimensional field data, but only little is known about their behaviour on three-dimensional synthetic data and three-dimensional field data. Particularly, it is not known whether Marchenko methods are sufficiently robust for sparse acquisition geometries that are found in practice. Therefore, we start by performing a series of synthetic tests to identify the key acquisition parameters and limitations that affect the result of three-dimensional Marchenko internal multiple prediction and subtraction using an adaptive double-focusing method. Based on these tests, we define an interpolation strategy and use it for the field data application. Starting from a wide azimuth dense grid of sources and receivers, a series of decimation tests are performed until a narrow azimuth streamer geometry remains. We evaluate the effect of the removal of sail lines, near offsets, far offsets and outer cables on the result of the adaptive double-focusing method. These tests show that our method is most sensitive to the limited aperture in the crossline direction and the sail line spacing when applying it to synthetic narrow azimuth streamer data. The sail line spacing can be interpolated, but the aperture in the crossline direction is a limitation of the acquisition. Next, we apply the adaptive Marchenko double-focusing method to the narrow azimuth streamer field data from the Santos Basin, Brazil. Internal multiples are predicted and adaptively subtracted, thereby improving the geological interpretation of the target area. These results imply that our adaptive double-focusing method is sufficiently robust for the application to three-dimensional field data, although the key acquisition parameters and limitations will naturally differ in other geological settings and for other types of acquisition. 相似文献
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采用弹性波全波形反演方法精确重建深部金属矿多参数模型,建模过程采用基于地震照明的反演策略.首先给出基于照明理论的观测系统可视性定义,利用可视性分析构建新的目标函数,对反演目标可视性较高的炮检对接收到的地震记录在波场匹配时占有更高的权重,确保了参与反演计算中的地震数据的有效性;其次将给定观测系统对地下介质的弹性波场照明强度作为优化因子,根据地震波在波阻抗界面处的能量分配特点,自适应补偿波场能量分布和优化速度梯度,以提高弹性波全波形反演过程的稳定性和反演结果的精度.理论模型和金属矿模型反演试验结果表明,基于可视性分析和能量补偿的反演策略可以使弹性波全波形反演更快地收敛到目标函数的全局极小值,获得适用于金属矿高分辨率地震偏移成像的多参数模型. 相似文献
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Gaussian beam depth migration overcomes the single‐wavefront limitation of most implementations of Kirchhoff migration and provides a cost‐effective alternative to full‐wavefield imaging methods such as reverse‐time migration. Common‐offset beam migration was originally derived to exploit symmetries available in marine towed‐streamer acquisition. However, sparse acquisition geometries, such as cross‐spread and ocean bottom, do not easily accommodate requirements for common‐offset, common‐azimuth (or common‐offset‐vector) migration. Seismic data interpolation or regularization can be used to mitigate this problem by forming well‐populated common‐offset‐vector volumes. This procedure is computationally intensive and can, in the case of converted‐wave imaging with sparse receivers, compromise the final image resolution. As an alternative, we introduce a common‐shot (or common‐receiver) beam migration implementation, which allows migration of datasets rich in azimuth, without any regularization pre‐processing required. Using analytic, synthetic, and field data examples, we demonstrate that converted‐wave imaging of ocean‐bottom‐node data benefits from this formulation, particularly in the shallow subsurface where regularization for common‐offset‐vector migration is both necessary and difficult. 相似文献
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控制照明与面向目标成像的观测系统设计 总被引：1，自引：0，他引：1
Liu Shouwei Geng Jianhua Feng Wei 《应用地球物理》2005,2(4):230-234
常规地震观测系统设计方法基于地下水平层 状介质的假设,通常不能适应复杂构造情况。我们 从控制照明的思想出发,提出了一种面向目标成像 的地震观测系统设计方法,该方法需要一个由初步 地震解释得到的速度模型。利用单程傅立叶有限差 分波场传播算子将目标层的平面源延拓到地表,通 过分析从目标层延拓到地表的波场能量的分布,可 以确定目标层成像所需要的炮点或者检波点的位置。 利用SEG-EAGE盐丘模型数值试算结果表明,该方法 用于设计面向目标成像的特定地震采集系统。 相似文献
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河道砂体宽/窄方位三维观测系统地震物理模型分析 总被引：1，自引：0，他引：1
The effect of the wide and narrow azimuth 3D observation systems on seismic imaging precision is becoming a hot area for studies of high precision 3D seismic acquisition methods in recent years. In this paper we utilize 3D physical seismic modeling experiments. A 3D channel sand body physical seismic model is constructed and two acquisition systems are designed with wide azimuth （16 lines） and narrow azimuth （8 lines） to model 3D seismic data acquisition and processing seismic work flows. From analysis of migrated time slice data with high quality and small size, we conclude that when the overlying layers are smooth and lateral velocities have little change, both wide and narrow azimuth observation systems in 3D acquisition can be used for obtaining high precision imaging and equivalent resolution of the channel sand body. 相似文献
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Extending illumination using all multiples: application to 3D acquisition geometry analysis 下载免费PDF全文
下载免费PDF全文 Recent advances in survey design have led to conventional common‐midpoint‐based analysis being replaced by subsurface‐based seismic acquisition analysis, with emphasis on advanced techniques of illumination analysis. Among them is the so‐called focal beam method, which is a wave‐equation‐based seismic illumination analysis method. The objective of the focal beam method is to provide a quantitative insight into the combined influence of acquisition geometry, overburden structure, and migration operators on the resolution and angle‐dependent amplitude fidelity of the image. The method distinguishes between illumination and sensing capability of a particular acquisition geometry by computing the focal source beam and the focal detector beam, respectively. Sensing is related to the detection properties of a detector configuration, whereas illumination is related to the emission properties of a source configuration. The focal source beam analyses the incident wavefield at a specific subsurface grid point from all available sources, whereas the focal detector beam analyses the sensing wavefield reaching at the detector locations from the same subsurface grid point. In the past, this method could only address illumination by primary reflections. In this paper, we will extend the concept of the focal beam method to incorporate the illumination due to the surface and internal multiples. This in fact complies with the trend of including multiples in the imaging process. Multiple reflections can illuminate a target location from other angles compared with primary reflections, resulting in a higher resolution and an improved illumination. We demonstrate how an acquisition‐related footprint can be corrected using both the surface and the internal multiples. 相似文献
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Seismic migration can be formulated in terms of two consecutive downward extrapolation steps: refocusing the receivers and refocusing the sources. Applying only the first focusing step with an estimate of the focusing operators results in a common focal point (CFP) gather for each depth point at a reflecting boundary. The CFP gathers, in combination with the estimates of the focusing operators, can be used in an iterative procedure to obtain the correct operators. However, current 3D seismic data acquisition geometries do not contain the dense spatial sampling required for calculation of full 3D CFP gathers. We report on the construction of full 3D CFP gathers using a non‐full 3D acquisition geometry. The proposed method uses a reflector‐orientated data infill procedure based on the azimuthal redundancy of the reflection data. The results on 3D numerical data in this paper show that full 3D CFP gathers, which are kinematically and dynamically correct for the target event, can be obtained. These gathers can be used for iterative updating of the 3D focusing operators. 相似文献