共查询到20条相似文献，搜索用时 62 毫秒
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山西省清徐县区域地质调查项目设计800、2000、3000 m科学钻探孔，以调查填补新生界底板埋深控制空白区，各孔钻入基岩30 m完钻。要求全孔取心，岩心采取率≮85%，岩心直径≮60 mm，采用塑料保护管采取原状岩样。针对超深软土层、各组地层特性及厚度未知、钻遇基岩完钻深度未知、大直径高保真全孔取心、项目价格远低于目前市场成本等难题，经过“水源钻机+大提钻取心+长裸眼孔段”实施800 m孔、“岩心钻机+绳索取心+套管固井”实施640 m参数对比孔，创新性使用“水源钻机+绳索取心+长裸眼孔段”工艺完成了2000 m孔的施工。该工艺岩心采取率达到93%，孔径和孔斜符合地质要求，为3000 m孔顺利施工打下了坚实的基础，为同类型项目提供了经验和借鉴。 相似文献
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针对硬岩及复杂地层取心钻进效率低、钻头寿命短的问题,依托“深海钻探技术与工程支撑”项目研制了?215.9 mm四牙轮取心钻头。通过合理布置牙轮角度与分布、优化取心结构,有效提高岩心采取率,保证钻头在硬岩中的钻进速度与可靠性。在之前进行了陆地试验和海洋试验并不断优化改进的基础上,本次在内蒙古自治区呼和浩特市清水河县首次进行了实验性的地热勘探取心施工,全段地层均为高研磨性、高硬度花岗岩,取心困难。采用?215.9 mm牙轮取心钻头配合常规的取心钻具,钻进效率达1.2 m/h,岩心采取率为70%~90%,取得了较好的应用效果,为海洋钻探硬岩取心提供了技术保障。 相似文献
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豫北地区施工的煤层气参数井试1井,要求在井深1 072～1 109 m处取心37 m,取心率达到90%以上,取心时间小于2min/hm,以准确获取山西组二1煤层的储层参数.为满足设计要求,选择平顶山五环实业有限公司研制的大口径绳索取心器,并根据地层特点,设计了81/2胎体式三阶梯PDC复合片绳索取心钻头及钢体式多阶梯硬质合金取煤钻头.在施工过程中选择了合理的钻进参数和泥浆性能,并按照拟定的操作程序采取了相应的技术措施,实际岩心采取率在煤岩段达到91.3%,在基岩段高达95.8%,完全满足了煤层气参数井对目的层取心的要求. 相似文献
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石山金矿钻探施工存在一个突出的技术难题，就是取心困难，达不到地质要求。过去在该区使用大口径钻进，平均采取率不足61％；80年底，我队一机台在该区采用小口径金刚石钻进，施工的ZK1孔，孔深95.39米，90％工作量采取率低于规程要求，30余米无岩心，平均采取率31.9％，矿心采取率28％，地质不能利用。事故停待多，纯钻利用率仅14.1％，施工周期一个半月。1981年6月，我分队三号机在该区进行普查钻探。地质设计了四个85°斜孔，共700米工作量。要求岩心采取率不低于65％，不得有岩心为零的回次；矿 相似文献
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CSAMT 法在辽西康杖子区深部探矿中的应用 总被引：5，自引：0，他引：5
可控源音频大地电磁法(CSAMT)具有探测深度大、横向分辨率高、抗干扰能力强的特点,在深部找矿勘探中有着重要的指导意义。肖家营子铜钼矿床是辽西地区一个大型矽卡岩型金属矿床,大部分矿体是隐伏矿体,矿区外围的康杖子区与本区有相似的成矿地质环境,成矿地质条件优越.矿体与围岩电性差异明显,通过应用CSAMT,矿体具有低电阻特点,根据成果推断解释,对深部有利成矿部位进行了钻探验证,取得了理想的探矿效果,在矿区外围取得第二深度空间找矿重大突破。 相似文献
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Trends in landslide occurrence in Nepal 总被引：2，自引：0，他引：2
David N. Petley Gareth J. Hearn Andrew Hart Nicholas J. Rosser Stuart A. Dunning Katie Oven Wishart A. Mitchell 《Natural Hazards》2007,43(1):23-44
Nepal is a mountainous, less developed kingdom that straddles the boundary between the Indian and Himalayan tectonic plates.
In Nepal, landslides represent a major constraint on development, causing high levels of economic loss and substantial numbers
of fatalities each year. There is a general consensus that the impacts of landslides in countries such as Nepal are increasing
with time, but until now there has been little or no quantitative data to support this view, or to explain the causes of the
increases. In this paper, a database of landslide fatalities in Nepal has been compiled and analysed for the period 1978–2005.
The database suggests that there is a high level of variability in the occurrence of landslides from year to year, but that
the overall trend is upward. Analyses of the trends in the data suggest that there is a cyclicity in the occurrence of landslide
fatalities that strongly mirrors the cyclicity observed in the SW (summer) monsoon in South Asia. Perhaps surprisingly the
relationship is inverse, but this is explained through an inverse relationship between monsoon strength and the amount of
precipitation in the Hill District areas of Nepal. It is also clear that in recent years the number of fatalities has increased
dramatically over and above the effects of the monsoon cycle. Three explanations are explored for this: land-use change, the
effects of the ongoing civil war in Nepal, and road building. It is concluded that a major component of the generally upward
trend in landslide impact probably results from the rural road-building programme, and its attendant changes to physical and
natural systems. 相似文献
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2010年,美国铀矿总共施工7 209个钻孔,总进尺1 493 520 m;生产铀1 628.55 t;铀矿业总支出费用为2.773亿美元,其中铀矿地勘费支出为3 450万美元,占铀矿业总费用的12.44%。铀矿地勘钻探费用为4 460万美元,占铀矿业总费用的16.08%。 相似文献
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环境和灾害是威胁人类生存的两大挑战性问题。由人类活动导致的自然环境破坏和恶化是一个长期累积的过程,类似于人体所患的慢性疾病,对其认识和解决不仅依靠多种条件,也需要很长时间的持久努力。自然灾害的发生一般是短时间内的突然事件,类似人体的急性疾病。为最大限度地减轻自然灾害给人类社会造成的损失,需要实施事先预防、灾前预警、灾时应急和灾后重建的系统工程,其中地球科学家的责任之一是找出有效的宣传演练,使社会各界充分认识灾害的危险性,做好必要的防灾准备。最近20 a来中国的减灾实践经验还说明,为进一步提高减灾的效益,要用科学观念指导各领域的减灾工作,在国家一级层次上要实行多部门协调、多学科合作的综合管理,并注重对灾害发生的规律性研究。例如对群发性灾害链过程及其潜在影响的估计,这对制定区域性可持续发展规划具有重要意义。 相似文献
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环境地球化学学科在中国生态文明和美丽中国建设、国际环境公约履约及过去全球变化研究中发挥着越来越大的作用。本文简要回顾了中国过去十年在环境地球化学领域的部分研究进展,介绍了汞、持久性有机污染物和其他重金属污染物长距离传输研究进展;总结了汞、镉、锑、铊等非传统稳定同位素在地表生物地球化学循环过程中的同位素分馏规律及污染来源和环境过程示踪方面的研究进展;回顾了传统稳定同位素地球化学与污染示踪及过去全球变化方面的研究进展。指出了以上研究方向还存在的问题及未来研究方向。 相似文献
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Radon is a radioactive gas emanating naturally from uranium rich granites and shales. It may be emitted from the ground surface into the atmosphere as a gas, or it may be dissolved into stream water and transported over distance. The levels of radon gas in soils at ground surface depend on a number of factors relating to the source of the gas and to its transmission. Igneous rocks contain the highest mean concentrations of radium and uranium. The depth of cover is relevant also. Surveys over the years by the National Radiological Protection Board (NRPB) and others have indicated that the highest concentrations in the United Kingdom occur in Cornwall, Devon and northeast Scotland. However, recent reports have indicated that high concentrations of the gas may be detected in small pockets in counties outside of those considered at high risk. This survey relates to a series of measurements taken in and around Darlington, County Durham. The results showed the presence of small areas with strong concentrations of radon in soil gas, but only minor levels of dissolved gas in stream waters. 相似文献
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