逆时偏移双向照明波场分离成像条件

通过对波场分离互相关成像条件与炮-检点双向照明互相关成像条件进行研究,将两种方法在噪声消除和补偿成像振幅畸变方面的优势进行结合,提高成像分辨率,改进现有成像条件。其主要步骤是将震源和检波点波场分离成它们的单程波传播分量,采用双向照明补偿互相关成像条件对需要的波场进行成像。通过对模型试算,验证了笔者提出的成像条件能有效的压制噪音,补偿成像振幅。     

基于能量范数优化的振幅保真逆时成像条件及其应用优势

逆时偏移成像条件的应用是逆时偏移成像中的一个重要环节,直接影响逆时偏移成像效果。为了改善逆时偏移成像效果,提高成像精度,开展逆时偏移成像条件的研究是很有必要的。这里给出了4种逆时偏移成像条件:(1)互相关;(2)归一化互相关;(3)能量聚焦;(4)振幅保真成像条件,提出了一种优化成像条件的策略(组合优化策略),推导出了一种利用能量范数优化的振幅保真逆时偏移成像条件,并将这5种成像条件用于简单模型及复杂模型试算,分别从噪音压制和振幅补偿这两方面对5种成像条件的成像结果进行了比较分析,在成像效果和成像精度的改善方面,阐明了优化的振幅保真成像条件的特点及适用性,突出优化的振幅保真成像条件的优势,并验证了优化策略的可行性。     

地震波逆时偏移中两种成像条件应用效果对比

成像条件是实现地震波场准确成像的关键环节,而优化逆时成像条件在改善逆时成像应用效果中的作用尤为明显。为此,从零井源距和非零井源距脉冲响应出发,系统对比了常规相关法逆时成像条件和基于行波分离法逆时成像条件的逆时偏移脉冲响应波场差异,分析了逆时偏移低波数噪声的成因机理及波场规律,同时以复杂断陷理论模型和SZ工区实际三维地震资料为例,系统对比了两种逆时成像条件的成像应用效果。研究结果表明,采用基于行波分离法逆时成像条件的成像结果能够有效衰减逆时偏移低波数背景噪声,恢复掩盖在这种背景噪声之下的有效地震成像信息,地层细节刻画更加清晰,这可为当前复杂波场和复杂构造高精度地震成像提供方法指导。     

基于VSP的透射PS波成像

利用弹性波动方程进行了非零偏移距VSP波场的数值模拟,通过偏振投影和中值滤波技术相结合进行波场分离,对分离后的反射P波和透射PS波利用动校正(NMO)和VSPCDP叠加技术进行成像。成像结果表明:透射PS波成像与反射P波成像具有同样良好的效果,而且透射PS波成像是反射波成像很好的补充。利用透射PS波成像不需要增加数据采集的成本,所以透射波成像技术将会在石油工业中被广泛采用。     

基于屏方法的弹性波叠前深度偏移

弹性波成像是多分量地震勘探需要解决的关键技术之一。借鉴声波方程中傅立叶有限差分算子中的有限差分补偿方法,对弹性波相屏传播算子进行了大角度校正。在求取成像值时,采用了矢量成像条件,即通过极化矢量,将各分量投影极化方向,然后再成像,从而使波场中的信息得到充分利用,同时解决了P-SV波成像过程中的极性不一致问题。这样,便可以叠加多炮的成像结果,从而提高成像质量。利用模型数据,对大角度相位校正后的弹性屏延拓算子和矢量成像条件进行了试验,成像效果理想。      

地质材料结构与功能射线成像方法与技术

地质材料结构与功能射线成像是采用射线对地球自然物质进行结构与功能成像,是研究地质材料物质组分、结构、特性与功能的重要手段,是认知地质现象、过程与动因的重要途径。在分析射线成像方法的基础上,分别梳理地质材料表面结构成像、三维结构成像与原位结构成像方法技术及适用条件,提出了地质材料功能成像方法与技术,并指出了地质材料结构与功能射线成像适用条件与发展趋势:（1）可见光、红外射线束和电子束射线等可实现地质材料表面的高精度成像;（2）X射线、γ射线和中子射线能量较高,可穿透地质材料实现三维成像;（3）地质材料的颗粒、矿物与基质等三维内部结构的静态成像研究已经比较成熟;地质材料原位（温度、应力和空隙压力等物理场）条件下的结构进行成像,是近年来地质材料结构成像的发展趋势;对地质材料的生成富集、储集、渗流等功能及过程进行射线成像是未来地质资源能源开发的重大需求,目前仍处于初步探索阶段。     

GPU并行加速的多步逆时偏移在东濮前梨园地区的应用

为了解决东濮油田复杂断块成像难题,笔者采用了多步逆时偏移成像方法,并使用了GPU进行并行加速。经过GPU并行加速的多步逆时偏移成像方法解决了RTM计算效率低的应用限制问题,并成功应用于复杂断层成像处理中。通过对前梨园三维地震资料的偏移成像处理,验证了逆时偏移成像技术在处理东濮地下复杂小断块和兰聊大断层上具有成像优越性;偏移效率分析试验证明了基于GPU并行加速的逆时偏移成像方法,能有效地提高计算效率75倍。     

多尺度地震资料联合成像

为改善储层目标区域的成像质量,结合地面地震、VSP和井间地震的各自优势,采用归一化后的自适应叠加方法,实现3种资料偏移结果的联合成像,以达到各种资料优势互补、提高成像精度的目的。为了给联合成像提供精度较高的单种资料成像剖面,采用傅里叶有限差分叠前深度偏移算法实现地面地震资料成像;在VSP和井间地震资料的叠前成像中采用了基于起伏地表直接下延法成像思想,基于傅里叶有限差分延拓算子得到VSP和井间地震偏移结果。模型试算和实际资料的处理验证了多尺度地震资料联合成像法的正确性和有效性。     

逆时偏移中的归一化加权互相关成像条件及应用

成像条件是决定声波方程叠前逆时深度偏移效果的重要因素。常规的归一化互相关成像条件能补偿深部地层的反射波能量,但无法压制地震波逆时偏移过程中产生的偏移噪声。针对归一化互相关成像条件的主要缺陷,从二维声波方程出发,在交错网格空间中推导了声波方程逆时延拓的高阶有限差分格式和PML吸收边界条件,进而在对常规互相关成像条件分析的基础上对其进行改进,给出了一种加权互相关成像条件,即在成像过程中利用炮检波场的夹角进行加权校正,以实现只利用炮点下行波场与接收点上行波场进行成像的目标。模型数据和实测资料偏移结果表明,归一化加权互相关成像条件成像效果明显优于常规归一化互相关成像条件。     

波动方程角度域共成像道集

针对基于波场深度递推的波动方程叠前深度偏移成像方法难以准确地给出如Kirchhoff积分叠前深度偏移成像方法的偏移距域共成像道集的不足,在分析研究现有的各种波动方程偏移成像共成像道集方法的基础上,利用波场外推的单平方根算子和波场的窗口Fourier框架展开与重构方法,提出一种局部角度域共成像道集方法——成像点处反射角共成像道集方法.把这种角度域共成像道集方法应用于国际标准的Marmousi模型数据和一条实际二维地震数据都取得了理想的结果.提出的波动方程反射角度域共成像道集方法可为进一步的叠前偏移数据振幅随角度变化分析和偏移速度分析工作提供基础.     

电磁波CT成像技术在防水工程场地勘查中的应用

电磁波CT成像技术是基于地下介质的物性差异,利用各种波源透视探测目的体及地质现象的一种地球物理方法,文章介绍了电磁波CT成像技术的原理和工作方法、某防水工程场地电磁波CT成像勘查实例及应用效果.     

电磁波CT成像技术在防水工程场地勘查中的应用

电磁波CT成像技术是基于地下介质的物性差异，利用各种波源透视探测目的体及地质现象的一种地球物理方法，文章介绍了电磁波CT成像技术的原理和工作方法、某防水工程场地电磁波CT成像勘查实例及应用效果。     

地震海洋学研究进展

传统船舶调查获取海洋水体温盐资料的方法在水平方向上分辨率较低,而用反射地震探测海洋水体特性的方法--地震海洋学,能有效提高海水温盐资料在水平方向上的分辨率.概述了近5年来地震海洋学的发展过程,重点介绍了地震海洋学方法在海洋锋面观测、水团边界划分、海洋内波分析、中尺度涡旋等方面的研究成果,以及AVO、全波形反演等反射地震处理方法在海洋水体特性研究中的应用.比较了地震海洋学方法与声层析技术、高频声技术等声学方法应用于海洋水体特性研究的异同.并展望了下一步研究工作的重点:①有关地震反射剖面的各种参数与海洋水体温盐结构物理模型的联系及其定量分析;②以研究海洋水体特性为目标的地震反射剖面的处理方法;③海洋地震调查历史数据的应用.     

Subsurface structural features of the basement complex and mineralization zone investigation in the Barramiya area,Eastern Desert of Egypt,using magnetic and gravity data analysis

In the Barramiya area, the majority of gold deposits are generally related with the quartz veins that associated with shear zones cutting the crystalline basement rocks. The quartz vein system is controlled by shear zone and general faults. The present study is to delineate the general faults, shear zones, geological limits, and basement rock relief, using airborne magnetic and gravity data analysis at the Barramiya gold mine and surrounding area, Eastern Desert of Egypt. To achieve our goal, we have applied on magnetic and gravity data the following techniques: reduction to pole (RTP), analytical signal, tilt derivative, total horizontal derivative, 3D Euler deconvolution, downward continuation, and source parameter imagining power spectrum techniques. The analytical signal used to map the types of rock boundaries. Tilt derivative and total horizontal derivative filters helped to delineate fractures and the contact zones of the formations that host the main Barramiya shear zone. 3D Euler deconvolution techniques helped to delineate the fault trends which represented at the following direction: NNE–SSW and NNW–SSE. The average depths of both regional and residual causes have been estimated by applying downward continuation, source parameter imagining, and power spectrum techniques. According to the results of the present study, the depth of the basement rocks is relatively high (~?80-m depth) in the western part of the study area and the basement rocks cropped out in the surface at the rest of the area. Our results are coinciding with the previous geological studies.     

新疆塔县石头城一带中更新世冰碛物的发现及地质意义

笔者首次在塔县的老兵站、石头城和加油站等3处发现了古冰碛物,均呈残留冰碛台地分布,台地高程约为3 100m,表面可见大量正长岩漂砾。漂砾风化穴的主要类型为边墙形、蜂巢型和底穴型。在侵蚀切割该古冰碛物的砂砾层中,得到(62.07±2.44)ka的光释光年龄。同时与附近墓士塔格山和公格尔山古冰川的对比研究,表明该冰碛物时代可能为中更新世倒数第二次冰期,为塔县县城西侧斯顿古冰川向东冰进的产物。该冰碛物的发现具有重要的地质意义:可将斯顿山第四纪冰川遗迹划分为中更新世的倒数第二次冰期、晚更新世的末次冰期,以及全新世的新冰期和小冰期;进一步指示塔什库尔干断裂的左行走滑正断层性质;更新世,斯顿古冰川与墓士塔格冰川各自有明确的界线,不可能形成一个统一的冰盖。     

塔中北斜坡奥陶系鹰山组岩溶储层特征及古岩溶发育模式

塔中北斜坡奥陶系鹰山组碳酸盐岩古岩溶发育,油气资源丰富,具有广阔的勘探开发前景。本次利用岩石化学分析、岩芯钻井、地震测井及成像测井资料,对岩溶储层发育规律及岩溶缝洞发育模式进行研究。认为:鹰一段和鹰二段发育质纯厚层灰岩地层,属强岩溶层组,溶蚀孔,溶蚀裂缝及溶洞均发育,后期古岩溶作用是该区油气聚集的主要场所。垂向岩溶缝洞系统主要发育在鹰山组顶面以下0~50 m及80~180 m范围。同时,溶洞在该区发育,洞穴型岩溶是该区优质岩溶储层,钻井过程常伴有放空、水漏失现象。结合古地貌特征,建立了ZG18~ZG22井区古岩溶缝洞系统发育模式,为岩溶储层预测及勘探开发井位部署提供地质依据。      

From financialization to operations of capital: Historicizing and disentangling the finance–farmland-nexus

This largely programmatic paper offers a new way of thinking through the incorporation of farmland into financial markets. Building on the notion of “operations of capital”, it sketches analytical entry points for scrutinizing the inner workings of agri-finance capital formation. The concept of operations can make two useful contributions to the existing discussion. First, it helps provide a more nuanced historicization of the entanglement between finance and farmland. Finance has a long history of penetrating agriculture and the new quality of the contemporary coupling of finance and farmland only becomes fully visible when adopting a more nuanced historical perspective. Rather than imagining the history of capitalism as one where industrial capitalism gives way to financialized capitalism, the concept of operations sensitizes us for the situated modes, processes and practices of financial economization that have reworked economy, society and nature at specific historical conjunctures.Second, it allows us to move beyond simply treating “financialization” as explanans. Shifting attention to the situated practical activities of global finance, it eventually helps us explore central categories of financial economization (“capital”, “resources”, “property” and “value”) as practical accomplishments rather than taking them for granted. Only then can we come to terms with how finance works through farmland in different geographical settings. Empirical material from an ongoing research project will support my arguments.     

Rethinking responsibility and care for a postcolonial world

Both responsibility and care have much to offer in thinking through the relationalities that make up a postcolonial world. Although contemporary political systems often posit responsibility and care within the context of individuated and autonomous selves, geographers have done much to relocate responsibility and care within narratives of interdependency - spatially and temporally. They have argued that both terms offer a route for thinking about ethical geographical relations between myriad places. In this article we take this project further, by looking at how the nature and shape of these relationships might be construed in a postcolonial world. We suggest that, through a more critical engagement with postcolonial thinking, any exploration of existing practices of responsibility and care will not only reveal the enormous potential of imagining these geographies as forms of existing and evolving relationalities, but will also lead us to interrogate the deployments of these terms in the context of past and present inequalities. We show that routing care and responsibility through postcolonial geographies moves us towards a more pragmatic responsiveness, one that involves a ‘care-full’ recognition of postcolonial interaction.     

Birds as lines: The production of alternative regimes of environmental management in the aftermath of a toxic disaster

This paper analyses how in the aftermath of one of the worst environmental disasters ever to occur in Spain – the Aznalcóllar Disaster – various environmentalist and conservationist groups mobilised migratory birds to bring new insights and the need for new precautions to the controversy elicited by the spill. The case study, thus, revolves around how environmentalists established a “hybrid collective action” to draw attention to unconsidered risks and impacts of the disaster and thereby make the case for open debate. Building upon this, I engage with two different, though interrelated, theoretical debates that contribute to a rethinking of environmental management (EM) as a social and materially situated practice. Drawing on the idea of “tactic” (De Certeau, 1984), I draw attention to the devices, actions and procedures that environmentalists carried out to resist attempts to minimise the spill and to undermine administrations’ assumptions of control, coherence and singularity associated the idea of management. Drawing on Tim Ingold’s latest work (2007, 2008, 2011), I analyse environmentalists’ most successful tactic: the enactment of migratory birds as “lines”. Together with other authors in this special issue, I will use this notion to make an argument against some of the assumptions of the “hybrid ontology”. In contrast to more essentialists and static notions of non-human agency and politics, the idea of line is particularly useful as a way of understanding how nature(s) can be effectuated differently and how this leads to the imagining of new regimes of cohabitation, human and non-human management and intervention.