基于波动方程的广义屏叠前深度偏移

地震波传播算子的计算效率和精度是制约三维叠前深度偏移的关键因素. 广义屏传播算子(GSP, Generalized Screen Propagator)是一种在双域中实现的广角单程波传播算子. 这一方法略去了在非均匀体之间发生的交混回响,但它可以正确处理包括聚焦、衍射、折射和干涉在内的各种多次前向散射现象. 通过背景速度下的相移和扰动速度下的陡倾角校正,广义屏算子能够适应地层速度的强烈横向变化. 这种算子可以直接应用于炮集叠前偏移,通过将广义屏算子作用于双平方根方程,还可以获得一种高效率、高精度的炮检距域叠前深度偏移方法,用于二维共炮检距道集和三维共方位角道集的深度域成像. 本文首先简述了炮检距域广义屏传播算子的理论,进而讨论了共照射角成像(CAI, Common Angle Imaging)条件,由此给出各个不同照射角(炮检距射线参数)下的成像结果,进而得到共照射角像集. 由于照射角和炮检距的对应关系,共照射角像集又为偏移速度分析和AVO(振幅随炮检距变化)分析等提供了有力工具.     

雄关漫道真如铁——论中国油气二次创业

半个多世纪以来，中国经历了油气资源的第一次创业，在祖国大陆和近海大陆架地区的新生代陆相碎屑岩沉积盆地中，发现了一批油气田，使原油年产量达1．67亿吨，位居世界第五，天然气疸这241亿立方米，居世界第十五位，成绩是巨大的，但是，1993年开始进口原油3000万吨，2000年进口原油7200万吨，严重影响国家经济建设，而且这种趋势还在不断发展，预测2010年将进口原油1亿吨，天然气200亿立方米，那么，中国油气资源的出路何在？作者指出，从中国大地构造演化来看，前新生代海相残留盆地还有巨大的油气潜力，尽管其勘探的难度是世界级的，但是，只要我们切实地依靠科学技术，进行油气资源的二次创业，困难上，在实践中克服困难，就可以发现更多的石油天然气，支持国家经济建设的持续发展。     

Geographies of Displacement: The Karenni and The Shan Across The Myanmar-Thailand Border

First, central to our analysis is the argument that human movement within and across borders fundamentally challenges the view of geopolitics based upon fixed territorial states, inter-state relations, national identities and citizenship; indeed the whole idea of "national geographic". Using the examples of the Karen and Shan peoples, we explore the processes and patterns of forced relocation, displacement and migration in the border regions of Myanmar and Thailand. Our main concern is with forced displacement as a result of political and ethnic conflict; specifically, how the Burmese military regime's desire for "national unity" within Myanmar's "national space" has influenced the militarily inspired displacements of hundreds of thousands of villagers and civilians within the border zones inhabited mostly by so-called "national minorities". We examine the particular problems of the so-called "internally displaced persons" within "national" boundaries compared with the "refugees" and "undocumented migrants" who make it across "international" space into Thailand. We illustrate the ways displaced people are represented by state agencies and the media as "threats" and "transgressors". We consider some of the "long term" aspects of the displacement problem along the Myanmar-Thai border and the vital contribution geographers can make to the study of displacement.     

Imposing Age and Spatial Structures on Inadequate Migration‐Flow Datasets*

With the elimination of the long‐form questionnaire from future decennial censuses and its replacement by a much smaller continuous monthly sampling survey (the American Community Survey), students of territorial mobility may find it necessary to deal with inadequate, missing, or inaccurate sample data on migration by adopting an approach that “improves” such data using information from different geographical areas, time periods, and data sources. We develop such an approach in this article and illustrate it with interregional migration flow data reported by the U.S. decennial censuses of 1980 and 1990 and by the 1985 Current Population Survey.     

Sectoral Shifts and Occupational Migration in the United States

This research is grounded in notions of differential economic restructuring across employment sectors and geographic space, as well as migration selectivity by occupation. A series of unconstrained competing‐destinations models were employed to analyze the response by workers in thirteen occupational categories to sectoral employment change, average wages, and distance. As was hypothesized, workers in occupations that require high levels of education and skills are more responsive, in terms of migration, to economic opportunities in alternative labor‐market areas. However, the results do not support the hypothesis that highly educated and skilled workers migrate longer distances. Further investigation suggests that opportunities for highly educated and skilled workers may be clustering in relatively few areas that are in relatively close proximity.     

烃类物质微渗漏机制及垂向运移的数值模拟

在前人烃类物质微渗漏机制研究基础上，建立了烃类物质微渗漏的概念模型，并且推导了烃类物质垂向运移的动力学模型。在动力学模型的基础上，通过数值模拟验证了烃类物质胶体气泡上升机制的合理性，并计算了不同情况下烃类物质垂向运移的平衡时间，进一步验证了烃类物质气泡上升机制满足运移速度快、流量少的特点。     

Cascaded Evolution of Mantle Plumes and Metallogenesis of Core- and Mantle-derived Elements

Mineral deposits are unevenly distributed in the Earth's crust, which is closely related to the formation and evolution of the Earth. In the early history of the Earth, controlled by the gravitational contraction and thermal expansion, lighter elements, such as radioactive, halogen-family, rare and rare earth elements and alkali metals, migrated upwards; whereas heavier elements, such as iron-family and platinum-family elements, base metals and noble metals, had a tendency of sinking to the Earth's core, so that the elements iron, nickel, gold and silver are mainly concentrated in the Earth's core. However, during the formation of the stratified structure of the Earth, the existence of temperature, pressure and viscosity differences inside and outside the Earth resulted in vertical material movement manifested mainly by cascaded evolution of mantle plumes in the Earth. The stratifications and vertical movement of the Earth were interdependent and constituted the motive force of the mantle-core movement.     

陕西彬县大佛寺D4钻孔勘察地球化学研究

运用烃类勘察地球化学方法，对鄂尔多斯盆地南部彬县大佛寺井田钻遇中休罗统煤层的耽钻孔，进行了垂向剖面多指标的综合地球化学研究。结果表明：剖面中所有岩样中的烃类物质均为热解烃生成初期演化阶段的煤成烃产物，具明显的同一性；由煤层至地表黄土，所有岩样中的烃类呈明显的、规律性垂直向上运移。这证实地下煤层烃类在近地表具有很好的地球化学信息显示，利用勘察地球化学方法找煤／煤层气是可行的。     

海拉尔盆地贝尔凹陷的油气运聚分析

海拉尔盆地贝尔凹陷是一个以白垩系沉积为主的陆相断陷区。采用条件分析法,对贝尔凹陷的油气运聚条件及其成藏的基本模式进行了系统研究,认为,贝尔凹陷在剖面上有3套成藏组合,其中中部成藏组合最佳;在平面上可分为5个运聚系统,其中以位于凹陷西北部的3个系统为最佳。该凹陷不同构造部位的运聚条件相差较大,生烃洼陷深部位的油气运移以砂岩储集层和断裂为主要输导通道,构造高部位的油气运移以断裂为主,而两者之间的油气输导则以不整合面和断裂为主。在油气运聚和成藏模式分析的基础上,认为贝尔凹陷油气运聚的有利条件主要包括生油凹陷有充足的油源、生油区内有继承性发育的圈闭构造以及各运聚要素间存在良好的时空配置关系3个方面。