共查询到20条相似文献，搜索用时 375 毫秒
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不提钻换钻头钻进技术是目前钻探施工中比较先进的技术,我队引进了BH—75不提钻换钻头钻具,在生产使用中发现钻具的悬挂机构及瞄向定位机构易损容坏,针对这种情况我们进行了改进,将悬挂机构改为圆环面接触,瞄向定位机构采用偏心圆切线滑动原理实现定位,经生产试验,改进后的钴具结构合理、性能可靠。 相似文献
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在分析各国整体切削具不提钻可换式钻头结构及存在主要问题的基础上,提出采用整体旋转切削具可换式钻头。在结构上采用弹簧、顶杆、球形铰组合来控制可换钻头的定位;使用一套输送器控制钻头的升降。这种设计结构克服了已有钻具结构复杂、不可靠等缺点,钻进效率高于普通绳索取心钻具10%~50%。 相似文献
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C. R. Twidale 《Australian Journal of Earth Sciences》2013,60(1-2):195-208
Some bornhardts are of lithological origin, others are tectonic (horsts), but most are not susceptible of explanation in either of these terms. They are developed in granite or gneiss that apparently is mineralogically similar to that underlying the adjacent plains, and they are not obviously defined by fault dislocations. For these bornhardts two major hypotheses have been advanced. According to many workers bornhardts are the last residuals surviving after long distance scarp retreat. For others they are structural forms developed on massive compartments that stand in marked contrast with the well‐jointed rocks that have been weathered and worn down to form the plains. Both of these hypotheses are theoretically feasible, but the field evidence (in particular the observed contrasts in fracture density between the granite of hill and plain; the evidence of subsurface initiation of both major and minor forms; the occurrence of bornhardts in narrow valleys within upland complexes and at all levels within the landscape, not just on divides; the fracture‐delineated outlines of the residuals; the association of bornhardts and multicyclic landscapes; the evidence of phased exposure; and the antiquity of the forms) are all consistent with the two‐stage concept. On the other hand, there is no evidence of long‐distance scarp retreat, and much of the field evidence is difficult to explain in such terms. 相似文献
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宝石的透明度 总被引：2，自引：0，他引：2
刘庆祥 《矿物岩石地球化学通报》1999,(4)
１ 宝石透明度的含义与分类宝石透明度与矿物的一样,均是指其透过可见光波的能力,主要与它们对光的吸收强弱有关,其大小可用透射系数来说明。宝石与矿物的区别也是显而易见的。矿物透明度仅划分为透明、半透明和不透明三类,并以０－０３ｍｍ厚的矿物薄片透光能力作为划分的依据。而透明度是评价宝石质量的标准之一,细分为透明、半透明、亚透明、微透明、不透明五类。２ 宝石透明度的影响因素宝石透明度的划分无厚度标准,既可以是不同厚度的戒指,也可以是不同厚度的雕件、挂件。而厚度是影响宝石透明度的因素之一,同种材料的宝石,… 相似文献
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Zeolites are present in altered pyroclastic rocks at many localities in Greece, and large deposits of potential economic interest are present in three areas: (1) the Evros region of the province of Thrace in the north-eastern part of the Greek mainland; (2) the islands of Kimolos and Poliegos in the western Aegean; and (3) the island of Samos in the eastern Aegean Sea. The deposits in Thrace are of Eocene-Oligocene age and are rich in heulandite and/or clinoptilolite. Those of Kimolos and Poliegos are mainly Quaternary and are rich in mordenite. Those of Samos are Miocene, and are rich in clinoptilolite and/or analcime. The deposits in Thrace are believed to have formed in an open hydrological system by the action of meteoric water, and those of the western Aegean islands in a similar way but under conditions of high heat flow, whereas the deposits in Samos were formed in a saline-alkaline lake. 相似文献
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Gregory H. Sambrook Smith Andrew P. Nicholas James L. Best Jonathan M. Bull Simon J. Dixon Steven Goodbred Maminul H. Sarker Mark E. Vardy 《Sedimentology》2019,66(2):391-407
Channel confluences are key nodes within large river networks, and yet surprisingly little is known about their spatial and temporal evolution. Moreover, because confluences are associated with vertical scour that typically extends to several times the mean channel depth, the deposits associated with such scours should have a high preservation potential within the rock record. Paradoxically, such scours are rarely observed, and their preservation and sedimentological interpretation are poorly understood. The present study details results from a physically‐based morphodynamic model that is applied to simulate the evolution and alluvial architecture of large river junctions. Boundary conditions within the model were defined to approximate the junction of the Ganges and Jamuna rivers, Bangladesh, with the model output being supplemented by geophysical datasets collected at this junction. The numerical simulations reveal several distinct styles of sedimentary fill that are related to the morphodynamic behaviour of bars, confluence scour downstream of braid bars, bend scour and major junction scour. Comparison with existing, largely qualitative, conceptual models reveals that none of these can be applied simply, although elements of each are evident in the deposits generated by the numerical simulation and observed in the geophysical data. The characteristics of the simulated scour deposits are found to vary according to the degree of reworking caused by channel migration, a factor not considered adequately in current conceptual models of confluence sedimentology. The alluvial architecture of major junction scours is thus characterized by the prevalence of erosion surfaces in conjunction with the thickest depositional sets. Confluence scour downstream of braid bar and bend scour sites may preserve some large individual sets, but these locations are typically characterized by lower average set thickness compared to major junction scour and by a lack of large‐scale erosional surfaces. Areas of deposition not related to any of the specific scour types highlighted above record the thinnest depositional sets. This variety in the alluvial architecture of scours may go some way towards explaining the paradox of ancient junction scours, that while abundant large scours are likely in the rock record, they have been reported rarely. The present results outline the likely range of confluence sedimentology and will serve as a new tool for recognizing and interpreting these deposits in the ancient fluvial record. 相似文献
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论松辽盆地地下水动力场演化与油气运移、聚集 总被引：15，自引：1，他引：15
松辽盆地地下水动力场具有明显的不对称性:盆地北部大气水下渗形成向心流；中央坳陷区发育泥岩压榨水形成的离心流和越流泄水；盆地南部以越流-蒸发泄水为特征，只有盆地边缘和隆起区的顶部有大气水下渗。泥岩压榨水形成的离心流是松辽盆地油气运移的主要动力。古水文地质的旋回性和离心流的阶段性，决定了油气的阶段性运移和在一个独立水动力体系内多个油环在内，气环在外，与沉积凹陷同心的阶梯式-环带状油气分布规律. 相似文献
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The thermal springs alongside Wadi Araba, Dead Sea and Jordan valley, Jordan, were investigated and sampled in a comprehensive field study of 2 weeks. Conventional physicochemical properties were measured in situ; dissolved solids and isotopic composition were analyzed. Two main spring locations on the east side of the Dead Sea were mapped. It became evident, that the hottest springs are among the closest to prominent faults; some springs are controlled by gas lift. Jordan’s hot springs are described by means of a broad hydrochemical and physicochemical data set and several figures are presented. Based on their hydrochemistry, the thermal springs are classified into four thermal provinces. Water genesis is discussed. Several geothermometers are applied to estimate reservoir temperatures. Observed discharge rate, water temperature and isotopic composition are compared with data from the literature. Although discharge and water temperature are reported to be constant over the last decades, groundwater overexploitation led to a shift of the isotopic composition, what is documented for the first time in Jordan. Thus, the effect of groundwater mining on Jordan’s hot springs can be stated as a fact. 相似文献
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Herman van der Wusten 《GeoJournal》2000,51(1-2):129-133
Capital cities are politico-administrative centers. They are command centers, they symbolize authority and also the unit that is governed. Primarily they are capitals of states, but other governance systems may also have capitals. In the European context there are now regional capital cities and at least the concept of a European capital. Particularly on account of their symbolic function but also for the uses made of its appearance in political life, the cityscape of capital cities is an interesting topic for research. There are different types of capital cities in Europe that give rise to different cityscapes. Existing urban networks and types of political regime are important in this respect. Although cityscapes are pretty stable, they are differently perceived over time and uses made of them also change. A research agenda for this intersection of historical, cultural and political geography should concentrate on the evolution of these cityscapes, their perception and the uses made of them in the acting out of politics. 相似文献
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《International Geology Review》2012,54(12):2184-2196
The controlling tectonic features of Sakhalin are the East Sakhalin horst, the northern fold belt, the western flank of the Tatar Strait geosyncline and the block-faulted area east and north of Aniwa Bay. The linear folds are associated with the Tatar Strait geosyncline. The block faulting is treated as Miocene, and earlier than the folding. — M. E. Burgunker. 相似文献