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991.
单孔波速测试的传统做法是在地面激振,在孔中接收,但该方法测试深度受限,测试精度较低,且对于海上钻孔来说,根本无法实现激振,故对于海洋工程钻孔的波速测试,则需要新技术来实现横波波速的获取。笔者介绍的悬挂式波速测井法将震源和检波器同时放入井孔中,摆脱了笨重的地面敲击震源,实现了波速测井设备的轻便化,由相距1 m的两个检波器接收S波的传播信号,为一发双收装置,利用传感器接收到震源传来的S波信号到达时间(初至)差,来确定钻孔所在处地层波速的一种新技术。该方法在南堡油田平台场址调查中发挥了重要作用,对120 m深的钻孔进行了横波测井,取得了良好的测试成果,为该工程项目提供了准确的剪切波速,为划分该场址的场地土类别发挥了重要作用。 相似文献
992.
993.
高精度航磁调查在新疆西天山地区的应用 总被引:2,自引:1,他引:1
介绍了高精度航磁调查在西天山地区的应用效果,在高精度航磁图上,磁异常信息极为丰富,不仅已知铁矿在图上反映明显,而且还新发现了50余处铁矿异常,在已经进行了查证的5处异常中,有4处见矿,分别为14号、20号、169号和374号。这4处异常的成功发现不仅带来了巨大的经济效益,也为今后利用高精度航磁调查进行找矿提供了典型的实例。根据该区高精度航磁调查实际效果,笔者认为在新疆西天山地区,乃至整个中国西部勘查程度较低的地区,进行高精度航磁测量,并进行快速的地面查证工作,是寻找铁磁性矿产行之有效的方法。 相似文献
994.
基于大炮初至的近地表层析反演方法研究及应用 总被引:1,自引:0,他引:1
详细研究了射线追踪、层析反演方法原理以及层析反演数值求解算法,提出了利用大炮初至直接建立初始地震模型,由小折射和微测井进行约束的层析反演近地表速度模型的处理流程,提出了基于多次回溯的高精度快速射线追踪算法和层析反演数值求解算法。采用双重网格技术提高正演模拟计算精度和层析反演的成像质量,另外,充分考虑多种质量控制方案,确保最终的反演速度模型精确。设计了10种不同地表地质条件的理论模型,进行模型试算,并在实际生产中应用,理论模型试算和实际资料反演结果证明了本文方法的正确性。 相似文献
995.
996.
997.
Suhas SHETYE Rahul MOHAN Sunil Kumar SHUKLA Sudhakar MARUTHADU Rasik RAVINDRA 《《地质学报》英文版》2011,85(3):549-558
Kongsfjorden is a fjord in Spitsbergen (Svalbard archipelago) that lies adjacent to both Arctic and Atlantic water masses and is therefore a suitable site to understand the effects of climate change on ecosystems. To decipher the effect of the lateral advection of transformed Atlantic water (TAW) within the fjord, spatial variations of foraminiferal tests, their test size variations and stable isotopic composition (δ13C and δ18O) in the surface sediments were studied. Total organic carbon and textural analyses were also carried out. The dominant benthic foraminifera included Nonionellina labradorica, Elphidium excavatum, Cassidulina reniforme, Quinqueloculina stalkeri and Islandiella islandica. Nonionellina labradorica was the predominant species in the outer fjord, whereas Elphidium excavatum and Cassidulina reniforme were dominant in the inner fjord. Total organic carbon and the test size of Nonionellina labradorica within the fjord were highly correlated (r2?=?0.97) and both showed a decreasing trend towards the inner fjord. Based on the distribution and abundance of Nonionellina labradorica as well as temperature profiles, we suggest that there was little or no major change in the lateral advection of TAW within the fjord in the immediate past. 相似文献
998.
A Kinematic Thermal Model for Descending Slabs with Velocity Boundary Layers: A Case Study for the Tonga Subducting Slab 总被引:3,自引:0,他引:3
For the purpose of investigating the influence of metastable olivine (MO) phase transformations on both deep seismicity and stagnation of slabs, we constructed a 2-dimensional finite element thermal model for a 120 Ma-old 50o dipping oceanic lithosphere descending at 10 cm/yr with velocity boundary layers, which would mitigate the interference of constant velocity field for the slab. The resulting temperatures show that most of intermediate and deep earthquakes occurring within the Tonga slab are occurring inside the 800oC and 1200oC isotherm, respectively. The elevation of olivine transformation near ~410 km and respective persistence of metastable olivine and spinel within the transition zone and beneath 660 km would thus result in bimodal positive, zonal, negative density anomalies, respectively. These results together with the resulting pressure anomalies may reflect the stress pattern of the Tonga slab: (i) slab pull force exerts above a depth of ~230 km; (ii) MO existence changes the buoyancy force within the transition zone and facilitates slab stagnation at a depth of 660 km; (iii) as the subducting materials accumulated over 660 km, deepest earthquakes occur due to MO transformation; (iv) a flattened ‘slab’ may penetrate into the lower mantle due to the density increment of Sp transformation. 相似文献
999.
Human Health Risk Assessment Model of Organic Pollution in Groundwater: Shijiazhuang Industrial Zone
In this study, a risk-based management model is developed and applied to an industrial zone. The models proposed by the United States Environmental Protection Agency and Han Bing have been improved by adding a residual ratio of volatile organic compounds (VOC) after boiling and deleting the related parameters in half-life. Using this improved model, an integrated process was used to assess human health risk level in the study area. Compared with water quality analysis, the results highlight the importance of applying an integrated approach for decision making on risk levels and water protection. The results of this study demonstrated that: (1) Compared with these permissible level standards in China (GB 3838-2002) and National Primary Drinking Water Regulations of the United States, the residents’ daily life had not been affected by the groundwater in this area (except for relative bad water quality of HB3-4 and HB3-6); (2) The typical detected organic contaminants of all groundwater samples were chloroform, carbon tetrachloride, trichloroethylene and tetrachloroethene, and the pollution sources were mainly industrial sources by preliminary investigations; (3) As for groundwater, the non-carcinogenic risk values of all samples do not exceed the permissible level of 1.0 and the carcinogenic risk values are relatively lower than the permissible level of 1.00E-06 to 1.00E-04; (4) Drinking water pathway of trichloroethylene and tetrachloroethylene mainly contribute to increasing the health risk of residents’ in study areas; (5) In terms of non-carcinogenic risk and carcinogenic risk, the health risk order for drinking water pathway and dermal contact pathway was: drinking water pathway > dermal contact pathway. 相似文献
1000.
Rayleigh面波各阶模式频散曲线对横波速度和层厚的敏感性探讨 总被引:1,自引:1,他引:0
Rayleigh面波勘探的目的在于有效利用频散曲线反演地层厚度及横波速度,而不同模式的频散曲线对横波速度和层厚的敏感性不同。通过求取介质参数变化10%后与参数不变化时的二组频散曲线的差值,得到各阶模式的频率~相速度差曲线,分析了Rayleigh面波各模式频散曲线对横波速度、层厚的敏感性。试验结果表明,基阶模式对于浅层的横波速度和层厚比较敏感,敏感区域主要集中在较窄的频带范围内。而高阶模式对于相对较深层的横波速度和层厚比较敏感,且频率范围分布较大,敏感性强的频段分布比较分散。研究结果可以为Rayleigh面波多模式联合反演提供理论依据。 相似文献