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551.
成因机理控制下的低电阻率油层发育特征及地质目标优选 总被引:3,自引:0,他引:3
通过建立低阻油层各种岩石物理成因与地质成因之间的关系,结合沉积环境、成岩作用、构造特征和成藏动力因素等综合分析低阻油层的发育特征,提出了5种具有典型意义的低阻油层有利勘探目标区带:(1)小规模、低幅度构造发育区,(2)天然水淹等构造运动活跃、流体非均质严重的区带,(3)岩性细、粘土矿物组合中蒙脱石含量高的区带,(4)弱水动力环境下砂泥岩薄互层发育区,(5)与火山碎屑沉积演化有关的黄铁矿等导电性矿物富集区。以上区带都是低阻油层的勘探目标优选区。由于钻井泥浆与地层水性质不同等侵入原因而造成的油、水层电性标准模糊则属于工程原因所导致的低阻。 相似文献
552.
基于空间语义角色的自然语言空间概念提取 总被引:5,自引:1,他引:4
根据空间信息的特点,从定义的空间语义角色入手,通过语义角色标注、短语识别以及概念模式匹配等手段,具体分析了自然语言中的空间实体、实体间空间关系以及空间过程的表达与提取方法。 相似文献
553.
弥散度是刻画孔隙介质中溶质运移和扩散的重要参数,对于污染物的预测和修复至关重要,但野外示踪试验往往会选择忽略真实存在的井内混合效应。通过室内砂槽实验方法,模拟具有水平分层结构的含水层,该含水层主要由3种介质充填而成。采用埋藏传感器和井中布设传感器2种监测方式,对比在有/无混合效应情况下,穿透曲线的形态差异,进而探究井内混合效应对弥散尺度依赖性的影响情况。实验结果表明,井内混合效应会使穿透曲线呈现阶梯式增长,并伴有显著的拖尾现象;当使用对流弥散方程进行计算时,混合效应会导致弥散度被高估;观测到的弥散度与真实弥散度的差异会随着注入井和观测井间距离的增加而增大;此外,2种观测方式(埋藏/井内)均能发现弥散的尺度依赖性,且井内混合效应显著增强了弥散尺度效应,该实验结果可为污染物运移的评价和预测提供参考。 相似文献
554.
泥页岩评价是油气地球化学研究的重要内容,是了解油气资源潜力的基础.以长岭凹陷吉页油1井青一段泥页岩为研究对象,在对其有机质丰度、有机质类型及成熟度等特征分析研究的基础上,结合测井曲线,对其非均质性进行刻画描述和分级评价.得到认识如下:1)泥页岩以Ⅰ型、Ⅱ型干酪根为主,成熟度处于低成熟-成熟阶段;2)建立了非均质性刻画模型,并对泥页岩进行了分级评价,青一段暗色泥页岩以Ⅱ级资源为主,部分为Ⅰ级资源,Ⅲ级资源较少,青一上段烃源岩整体资源级别要优于青一下段. 相似文献
555.
556.
西南印度洋中脊(SWIR)平均扩张速率约为14 mm/yr,是全球洋中脊系统的重要组成端元,因其具有慢速-超慢速扩张特征,引起全球科学家的广泛关注。基于前人对SWIR的综合研究成果,从构造和岩浆作用两个角度出发,系统地回顾了SWIR的形成和演化历史,探讨了岩浆的分布特征和地幔不均一性成因。SWIR的形成始于冈瓦纳大陆的裂解,中段洋脊区域(26~42°E)是印度洋最早开启的窗口,历经多次洋脊跃迁和扩展作用形成了斜向扩张展布,多分段的构造格局。地幔热点在冈瓦纳大陆裂解过程中扮演了关键角色,并对SWIR的洋底地貌和岩浆作用具有显著影响,其中Bouvet和 Marion热点在SWIR的西段和中段岩浆均留下了地球化学印迹。SWIR西段岩浆除却Bouvet热点影响之外表现出与大西洋-太平洋型玄武岩相似的同位素地球化学特征。在SWIR中段,39~41°E附近的岩浆具有显著的DUPAL异常特征,与冈瓦纳大陆的初始形成、裂解紧密相关。受俯冲改造的中—新元古代的造山带岩石圈地幔拆沉是造成SWIR中段地幔不均一性的重要根源。在SWIR东段,46~52°E区域内的局部岩浆组成异常,推测具有大陆地壳物质混染的成因。而在Melville转换断层以东,洋脊形成时间最晚,玄武岩的地幔源区受到了富集组分的交代作用,其同位素组成与相邻的中印度洋中脊(CIR)和东南印度洋中脊(SEIR)地幔源区具有亲缘性。 相似文献
557.
1990-2005年广州城市土地覆被景观变化 总被引:5,自引:1,他引:4
Urbanization has been the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbanization to understand landscape quantitative characteristics and its changes. Based on four land-cover type maps interpreted from remote sensing TM images of 1990, 1995, 2000 and 2005, combining gradient analysis with landscape metrics, the quantified spatial pattern and its dynamics of urbanization in Guangzhou was got. Three landscape metrics were computed within different regional areas including the whole study area, two transects along two highways (one N-S and the other W-E) and radiation zones with equal distance outwards the city center were set. Buffer zones for transects N-S and W-E were outlined along highways. The following questions should be answered in this paper: What responses were implied with changing spatial grain size or extent for landscape pattern analysis? Could gradient progress of urbanization be characterized by landscape pattern analysis? Did landscape metrics reveal urban expanding gradually? Were there directional differences in land cover landscape pattern during urbanizing development? The results gave some affirmative answers. Landscape pattern exhibited obviously scale-dependent to grain size and extent. The landscape metrics with gradient analysis could quantitatively approach spatial pattern of urbanization. A precise location for urbanized area, like city center and sub-center, could be identified by multiple landscape metrics. Multiple adjunctive centers occurred as indicated by analysis of radiation zones around the city center. Directional differences of landscape pattern along the two transects (N-S and W-E) came into being. For example, fragmentation of landscape in the transect W-E was obviously higher than that in the transect N-S. All in all, some interesting and important ecological implications were revealed under landscape patterns of two transects or radiation zones, and that was the important step to link pattern with processes in urban ecological studies and the basis to improve urban environment. 相似文献
558.
We describe the temporal and spatial litterfall and test the accuracy of different litter collection devices in a Sonoran Desert community. Two low-lying PVC litter trap designs were tested and compared against a standard IBP trap. The test traps collected significantly more plant litter than the IBP traps, which failed to capture most of the litter of ephemerals and low shrubs. The largest differences between the traps appeared after the pulses of growth of ephemeral plants. Data collection for a period of almost 2 years showed an annual total litterfall of 3·43 Mg ha−1for the test traps and 2·77 Mg ha−1for the IBP traps. These values are well above the average for deserts and fit better into the lower range of tropical dry forests. The test PVC traps are inexpensive, economical in collecting and sorting effort, and less prone to vandalism. Also, they can be laid in higher numbers than IBP traps, thus providing a better representation of the highly heterogeneous desert environment. 相似文献
559.
560.
Preferential flow pathways, such as soil pipes, are usually present in the soil of slopes. Subsurface flow through the soil pipes affects the subsurface drainage system and is responsible for sediment removal from slopes. However, a record of the inner structure of soil pipes has rarely been reported for slopes. A fibrescope examination of the morphology and flow phases in soil pipes in hillslopes underlain by a Quaternary sand–gravel formation provided the following information: the main pores of the soil pipes ran mostly parallel with the slope gradient; the cross‐sections of the soil pipes were approximately circular; and occurred on a few occasions; with some triple junctions being present. In addition, both full flow and partly full‐depth conditions occurred simultaneously in the soil pipe. The full flow condition has long been used in hydrological studies to model the pipe flow mechanism. Both the full flow condition and the partly full‐depth condition, however, must be examined closely in order to evaluate the subsurface hydrology in heterogeneous soil and the hydrogeomorphological processes of subsurface hydraulic erosion. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献