Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns

Cap-rock seals can be divided genetically into those that fail by capillary leakage (membrane seals) and those whose capillary entry pressures are so high that seal failure preferentially occurs by fracturing and/or wedging open of faults (hydraulic seals). A given membrane seal can trap a larger oil column than gas column at shallow depths, but below a critical depth (interval), gas is more easily sealed than oil. This critical depth increases with lower API gravity, lower oil GOR and overpressured conditions (for the gas phase). These observations arise from a series of modelling studies of membrane sealing and can be conveniently represented using pressure/ depth (P/D) profiles through sealed hydrocarbon columns. P/D diagrams have been applied to the more complex situation of the membrane sealing of a gas cap underlain by an oil rim; at seal capacity, such a two-phase column will be always greater than if only oil or gas occurs below the seal.These conclusions contrast with those for hydraulic seals where the seal capacity to oil always exceeds that for gas. Moreover, a trapped two-phase column, at hydraulic seal capacity will be less than the maximum-allowed oil-only column, but more than the maximum gas-only column. Unlike membrane seals, hydraulic seal capacity should be directly related to cap-rock thickness, in addition to the magnitude of the minimum effective stress in the sealing layer and the degree of overpressure development in the sequence as a whole.Fault-related seals are effectively analogous to membrane cap-rocks which have been tilted to the angle of the fault plane. Consequently, all of the above conclusions derived for membrane cap-rocks apply to both sealing faults sensu stricto (fault plane itself seals) and juxtaposition faults (hydrocarbon trapped laterally against a juxtaposed sealing unit). The maximum-allowed two-phase column trapped by a sealing fault is greater than for equivalent oil-only and gas-only columns, but less than that predicted for a horizontal membrane cap-rock under similar conditions. Where a two-phase column is present on both sides of a sealing fault (which is at two-phase seal capacity), a deeper oil/water contact (OWC) in one fault block is associated with a deeper gas/oil contact (GOC) compared with the adjacent fault block. If the fault seal is discontinuous in the gas leg, however, the deeper OWC is accompanied by a shallower GOC, whereas a break in the fault seal in the oil leg results in a common OWC in both fault blocks, even though separate GOC's exist. Schematic P/D profiles are provided for each of the above situations from which a series of fundamental equations governing single- and two-phase cap-rock and fault seal capacities can be derived. These relationships may have significant implications for exploration prospect appraisal exercises where more meaningful estimates of differential seal capacities can be made.The membrane sealing theory developed herein assumes that all reservoirs and seals are water-wet and no hydrodynamic flow exists. The conclusions on membrane seal capacity place constraints on the migration efficiency of gas along low-permeabiligy paths at depth where fracturing, wedging open of faults and/or diffusion process may be more important. Contrary to previous assertions, it is speculated that leakage of hydrocarbons through membrane seals occurs in distinct pulses such that the seal is at or near the theoretically calculated seal capacity, once this has been initially attained.Finally, the developed seal theory and P/D profile concepts are applied to a series of development geological problems including the effects of differential depletion, and degree of aquifer support, on sealing fault leakage, and the evaluation of barriers to vertical cross-flow using RFT profiles through depleted reservoirs. It is shown that imbibition processes and dynamic effects related to active cross-flow across such barriers often preclude quantitative analysis and solution of these problems for which simulation studies are usually required.     

盐井二次定向对接连通施工工艺

新汶矿业集团泰山盐化工ZJ03-PJ03井组为一对定向连通采卤井井组，采用二次定向钻井连通施工工艺，技术套管下入深度907．6m（8矿层顶板），有效地阻隔了上部含较多杂质的岩盐矿层，确保了卤水质量能满足盐化工的需要。本对接连通井组，采用随钻测量井斜、方位及钻进轨迹控制技术，为该井组的顺利对接提供了技术保障。     

天目湖流域丘陵山区典型土地利用类型氮流失特征

天目湖丘陵山区农业综合开发持续推进,大量林地转变为茶园,迫切需要认识茶园扩张对流域氮流失的影响.本研究选取茶园、次生马尾松林和毛竹林开展自然降雨条件下的径流小区实验,分析天目湖丘陵山区典型用地类型径流氮流失规律,为评估丘陵山区综合开发的水环境影响提供实测参数.研究表明:茶园、次生马尾松林和毛竹林地表径流TN浓度分别为11.25、2.83和3.60 mg/L,均以溶解态为主;壤中流TN浓度分别为27.16、3.59和1.06 mg/L,茶园和次生马尾松林均以溶解性无机氮(尤其是硝态氮)为主,毛竹林以溶解性有机氮为主;茶园、次生马尾松林和毛竹林的小区尺度地表径流系数均不到0.03,壤中流是丘陵山区径流的主要来源;茶园开发加剧了丘陵山区的氮素流失,茶园径流TN流失强度高达103.08 kg/(hm²·a),分别是次生马尾松林和毛竹林的7.6和23.2倍,壤中流贡献了流失总量的86.7%~99.7%.防治茶园径流氮流失需重点关注壤中流输出,在减量施肥的基础上,采取坡脚构建毛竹林生态缓冲带/在小流域出口布设塘坝等原位拦截措施,实现流域氮流失综合防控.     

VBA的开发

介绍了能够加强Ms Office功能的二次开发工具VBA语言，以及VBA的特点与优点；介绍了在Visul Basic中利用VBA的强大功能来实现具有Office界面、功能的方法。     

PS转换波界面二次源法射线追踪

界面二次源法是最近提出的一种最小走时射线追踪方法,尤其适合层状介质中走时和射线路径的计算.该方法相对于传统的最小走时树方法（如Moser法）,仅在物性界面上设置二次源,射线路径的方向只在层界面处发生改变,该方法最大程度地消除了射线路径的锯齿状现象,同时也避免了低变速区的射线路径多值现象,因此,它具有更高的追踪精度和效率.本文采用界面二次源法在各向同性介质中实现了PS转换波射线追踪,理论模型的计算证实了界面二次源法追踪PS转换波的准确性和高效性,同时该方法在各向异性介质中也很好地追踪出分离的PSV波和PSH波,因此该方法有利于横波分裂在地震勘探中的研究和应用     

梅雨锋生次级环流对暴雨的作用

本文采用了MM4中尺度数值模式对1991年7月5日08时至6日20时发生在江淮流域的梅雨锋暴雨过程进行了模拟。在模拟较理想的基础上，利用模式输出的高分辨率的动力协调资料，就暴雨过程中锋生次级环流各强迫项对暴雨的作用进行了诊断研究。结果表明：锋生次级环流对暴雨形成具有重要的作用，但在暴雨过程不同时期各项的作用差异很大。     

Accuracy assessment of the Mexican National Forest Inventory map: A study in four ecogeographical areas

The accuracy of the Mexican National Forest Inventory (NFI) map is derived in four distinct ecogeographical areas, using an assessment design tailored for the project. A main achievement of the design was to integrate the high diversity of classes encompassed at the most detailed subcommunity level of the classification scheme within a cost‐controlled statistically sound assessment. A hybrid double sampling strategy was applied to the 2.5 million‐ha study area. A total of 5955 reference sites were verified against their NFI map label. The availability of detailed quasi‐synchronous reference data for the 2000 Landsat‐derived NFI and the high diversity of mapped classes allowed a careful thematic analysis on the selected regions, relevant for national extrapolation. Global accuracy estimates of 64–78 per cent were registered among the four ecogeographical areas (two with mainly temperate climate and the other two with mainly tropical climate), with the lower accuracy levels found in areas more densely covered with forests. According to the estimates, the NFI map tends to underestimate the presence of temperate forest (especially oak) and overestimate the presence of tropical forest in the areas investigated. The analysis of confusions reveals difficulties in unambiguously interpreting or labelling forests with secondary vegetation, herbaceous and/or shrub‐like vegetation as well as distinguishing between aquatic vegetation types. The design proved useful from the perspective of accuracy assessments of regional maps in biodiverse regions.     

稠油成因研究综述

在阐述稠油地球化学特征基础上,对稠油的成因及其判识的最新研究进展进行了综述,稠油成因类型分原生型和次生型,其中,次生型稠油主要由生物降解、水洗和氧化作用分解、消耗或氧化原油中的烃类组分,使非烃和沥青质含量相对增加,致使原油密度和黏度增大,油质变稠.最后指出了目前稠油成因机制研究中存在的问题以及今后发展的方向.     

两株南极枝孢霉属真菌Cladosporium sp.NJF4和NJF6的次级代谢产物研究

南极因其独特的自然环境成为潜在、重要的微生物资源库,是产生新型生物活性物质和先导化合物菌株的潜在种源地,南极微生物正在成为创新药物研究新的重要资源。虽然近年来对南极微生物次级代谢产物的研究逐渐增加,但与温带和热带微生物研究相比仍处于初级阶段。对从南极普里兹湾海洋沉积物中获得的两株枝孢霉属真菌Cladosporium sp. NJF4和NJF6进行次级代谢产物分离及结构鉴定,获得20个化合物。化合物结构类型包括甾醇(1)、倍半萜类(7—8)、生物碱类(9—14)、二酮哌嗪(2—5、15—17)、芳香酸(6、18—19)等,其中倍半萜类(7—8)为首次从枝孢霉属真菌中分离得到,以上研究将为丰富南极微生物次级代谢产物库奠定一定的研究基础。     

中国西部局地蒸发水汽贡献率探讨

利用降水、湖水同位素数据并结合相关模型,对我国西部地区的二次蒸发效应以及不同类型水汽对区域降水的贡献率进行了定量的讨论,研究得到以下结论：①夏季风期间,天山-阿勒泰地区所受到的二次蒸发效应较为明显;而青藏高原地区,水体蒸发水汽的向上补给则是影响该区域在全年任何时段下氢氧同位素值发生变化的主要因素.②天山-阿勒泰地区在全年任何时段下均存在二次蒸发效应,且夏季风时的作用程度明显强烈,蒸发比值介于13%~20%,均值为16.7%,远远大于冬季风时的均值4.3%.③青藏高原地区不论是在夏季风还是冬季风期间,上风向水汽对区域降水的贡献率最大,所占比重基本大于50%,贡献率最小的是水体蒸发产生的水汽,其值普遍小于10%;而蒸腾作用产生水汽的贡献率介于两者之间.