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271.
地热钻井与岩心钻探有着孔径大、钻进进尺深的特点。更易产生坍塌、掉块、吸附等多种影响钻进的因素。本文通过一眼超深地热井(2 500 m)的施工,研究和配制了具有与岩芯钻探泥浆相区别的泥浆体系,保证了2 500 m地热井施工的顺利完成。 相似文献
272.
Mud volcanoes have provided much meaningful information about the deep Earth and the recent crustal and neotectonic movements in an area for over 200 years. However, the triggering mechanisms have puzzled geologists for a long time. This study investigated the factors controlling mud volcano activity and the triggering mechanisms of mud volcano eruptions on the southern margin of the Junggar Basin, NW China. The Baiyanggou, Aiqigou and Dushanzi mud volcanoes are all located along the Dushanzi Anticline, which belongs to the third anticline belt on the southern margin of the basin. The extensive, thick mudstone at depth provides a wealth of material for the formation of mud volcanoes. Simultaneously, the overpressure serves as the driving force for the eruption of the mud volcanoes. The torsional–compressional stress field created by the collision between the Indian and Eurasian plates not only enhanced the abnormal formational pressure in the region but also lead to the development of extensional faults in the core of the Dushanzi Anticline, which served as the conduits for the mud volcanoes. The continuous collision between the Indian and Eurasian plates and the regional torsional–compressional stress field may largely control the cyclical activity of the mud volcanoes and serve as their primary trigger mechanism. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
273.
现代黄河水下三角洲沉积体系中存有许多对工程不利的软土夹层和透镜体,它们主要是由高含水、高孔隙性的粘土质粉砂和粉砂质粘土组成,由于形成时的快速沉积和波浪作用等因素,使其具有明显的欠固结性,且其固结程度随深度变化呈无规律状.另外,因为软土中粘粒含量较高,颗粒问的水胶联结和静电引力与分子引力联结,而使其具有明显的触变性,从而使其较低的强度在受到破坏后也难以恢复. 相似文献
274.
在三疣梭子蟹(Portunus trituberculatus)的单体筐养养殖(SCBC)系统中,研究了不同的饲养空间大小对梭子蟹(幼蟹与成蟹)摄食行为与生长的影响。试验设置了四个饲养空间处理:空间长度分别为养殖蟹平均壳长的1倍、1.5倍、2倍及3倍,宽为长的一半。经6天试验,结果表明,1倍空间的幼蟹摄食行为发生变化,摄食次数[(1.2±0.45)次/d]和总进食时间[(31.2±6.89)min]比2倍与3倍的空间[(2.6±0.45)次/d,(83.1±13.66)min]明显减少,导致摄食量减少[前者为(0.0835±0.0269)g/g BW,后两者最高为(0.2014±0.0114)g/g BW],至第5天全部死亡。其它处理,随着空间的增大,摄食量增大,幼蟹的生长速率(蜕皮率,体重增长率)增加。其中,在2倍空间以上处理中,幼蟹表现有最高的成活率(100%)、蜕皮率(100%)以及体重增长率(86.5%—97.2%),同时有较低的饵料系数(1.31±0.11)。成蟹的试验结果与幼蟹类似,除1.5倍饲养空间外,该处理中幼蟹表现出对生长的胁迫,而成蟹的摄食行为和生长与2倍及3倍空间无差异。不同空间中梭子蟹的摄食与生长的差异与梭子蟹在这些处理中的保护性酶类(SOD,POD,CAT)和消化酶类(淀粉酶,蛋白酶,脂酶)的活性有密切关系。 相似文献
275.
The series connection of multistage pumping module is the common concept of deepwater riserless mud recovery drilling system. In this system, the influence of the mass of pumping module on the vibration of mud recovery line cannot be ignored, and the lumped mass method has been utilized to discretize the mud recovery line. Based on the analysis of different boundary conditions, the paper establishes the axial forced vibration model of the mud recovery line considering the seawater damping, and the vibration model analysis provides the universal solution to the vibration model. An example of the two-stage pumping system has been used to analyze the dynamic response of mud recovery line under different excited frequencies. This paper has the important directive significance for the application of riserless mud recovery drilling technology in deepwater surface drilling. 相似文献
276.
Sediments often occur as non‐normal size distributions composed of discrete, partially aggregated particle populations. These populations reflect provenance, dispersal pathways and their depositional environments. Recent experimental laboratory studies describing mud flocculation in turbulent marine systems prompted this investigation of the potential of aggregates to record size‐sensitive transport dynamics in a terrestrial fluvial system. Here, sediment‐size distributions in their natural condition of particle–aggregate mixtures are analysed by parametric statistics. A practical and freely available decompositional approach is outlined and field tested, which allows sediment to be viewed in both its conventional particulate form and as its naturally occurring mixture of transport‐stable aggregates and elementary particles. From a sequence of upward‐fining slack water couplets in the Flinders Ranges, South Australia, it is demonstrated that the characteristics, provenance and depositional history of fine‐grained sediments consisting of particle‐aggregate mixtures can best be understood fully by quantifying aggregation. 相似文献
277.
278.
通过对福建煤田地层特征及其对钻探影响的分析,阐述了在福建煤田钻探中所遇的主要问题,结合实践论述了低固相泥浆的主要性能和优点、以及低固相泥浆对预防处理水敏性地层的缩径和破碎、松散等不稳定地层的坍塌、掉块现象具有的效果,对保证施工的顺利进行、提高施工质量与效率的重要作用。 相似文献
279.
The Håkon Mosby Mud Volcano (HMMV) is a methane seep that is densely populated by the bacteria Beggiatoa spp. as well as by tubeworms of the Family Siboglinidae. Analyses of samples from seven stations located in five different habitats (bare sediments, bacterial mats, siboglinid fields, sediments with small patches of siboglinids and areas of ‘normal’ sea floor) revealed differences in the density and species‐level diversity of nematode communities. Total densities increased from stations inside the mud volcano and on its rim towards the ‘normal’ areas outside the volcano. Nematode species diversity was similar in samples from the siboglinid fields and the bare HMMV sediments. However, the sediment with patches of siboglinids collected outside the volcano was characterised by a diverse nematode community comprising 47 species, whereas the control sediments without siboglinids yielded only 27 species. The nematode assemblage at the bacterial mat site included only two identified species, Halomonhystera disjuncta and Sabatieria ornata, with H. disjuncta being strongly dominant. Terschellingia distlamphida, S. ornata and Aponema ninae dominated nematode communities at the siboglinid fields and in bare HMMV sediments. Species dominating at stations inside the caldera were found in comparable low densities in the sediment with siboglinid patches collected outside the volcano, but were missing in the background samples, where species of Endeolophos, Acantholaimus and Desmoscolex were dominant. Species diversity generally decreased with sediment depth. A subsurface‐dwelling nematode community was observed in the siboglinid fields and the bare sediments. Background sediments showed a sharp decline with 18–20 species at 0–2 cm versus three species at 3–5 cm sediment depth. The trophic composition of the nematode fauna at the HMMV showed a prevalence of deposit feeders at almost all stations, whereas background sediments exhibited a uniform distribution of non‐selective and selective deposit feeders and epistrate feeders. The high percentage of deposit feeders inside the mud volcano could be related to the grain‐size distribution and the significantly higher bacterial biomass compared to the control sediments. 相似文献
280.
本文运用粒级一标准偏差方法对FJ04孔146cm以上部分进行敏感粒度组分分析与提取,证明选取的敏感粒度组分是本区重要的环境替代性指标,其平均粒径的变化可以用来指示东亚季风的强弱。获得了东海北部泥质区3ka以来东亚冬季风强度的演化过程,结果表明东亚季风经历了两个主要的演变阶段:①3.1.15kaB.P.为东亚冬季风较弱,... 相似文献