Refinement of the Micro‐Distillation Technique for Isotopic Analysis of Geological Samples with pg‐Level Osmium Contents     

Nao Nakanishi  Tetsuya Yokoyama  Akira Ishikawa 《Geostandards and Geoanalytical Research》2019,43(2):231-243

In recent years, the ¹⁸⁷Re–¹⁸⁷Os isotope system has been increasingly used to study samples containing very small quantities of Os. For such samples, optimisation of measurement procedures is essential to minimise the loss of Os before mass spectrometric measurements. Micro‐distillation is a necessary purification step that is applied after the main Os chemical separation procedure, prior to Os isotope ratio measurements by negative‐thermal ionisation mass spectrometry (N‐TIMS). However, unlike the other separation steps, this procedure has not yet been optimised for small samples. In this study, we present a refined micro‐distillation method that achieved higher yields and allowed high‐precision R(¹⁸⁷Os/¹⁸⁸Os) expressed as ¹⁸⁷Os/¹⁸⁸Os measurements for small‐sized geological samples that contain only a few pg Os. The Os recovery in the micro‐distillation step was tested by changing the operating conditions including heating time and temperature, and amounts of oxidant and reductant. Recoveries were measured by the isotope dilution ICP‐MS method after the addition of ¹⁹⁰Os‐enriched spike solution. We found that the most critical factor controlling the chemical yield of Os during micro‐distillation is the extent of dilution of the reductant (HBr) by H₂O evaporated from the oxidant. A refined micro‐distillation method, in which the amount of oxidant solution is reduced from the conventional method, achieved an improved chemical yield of Os (~ 90%). This refined method was applied to the measurement of ¹⁸⁷Os/¹⁸⁸Os by N‐TIMS of varying test portions of the geological reference material BIR‐1a. The resulting ¹⁸⁷Os/¹⁸⁸Os ratios of BIR‐1a matched the literature data, with propagated uncertainties of 0.2, 1.1 and 11% digested sample quantities containing 150, 10 and 1 pg of Os, respectively.  相似文献   

天然海水硝酸盐氮同位素组成的蒸馏法测定     

杨志  陈敏  曹建平  邱雨生 《海洋学报》2012,34(3):72-79

建立了测定天然海水中硝酸盐氮同位素组成的蒸馏法,该方法主要是在碱性条件下利用戴氏合金将海水中的硝酸盐还原为氨,后利用稀盐酸吸收生产的氨,将得到的氨吸收液浓缩后干燥结晶,利用同位素比值质谱仪测定所得晶体的氮同位素组成。研究中开展了戴氏合金添加量及氨吸收溶液在不同条件下干燥结晶对氮同位素测值的影响研究。结果表明,戴氏合金添加量为3.0 g及60 ℃下直接干燥结晶为最佳的实验条件。所建立的氨蒸馏法氮空白值仅为(0.90±0.19) μmol,低于此前文献报道的氮空白值;氮同位素组成(δ15N)空白值为(-14.7±4.1)×10-3。运用所建立的氨蒸馏法实测得到的硝酸盐δ15N值与氨扩散法、硝酸盐直接测定法得到的数值非常吻合,进一步证明所建立氨蒸馏法的可靠性。改进后的氨蒸馏法适用于硝酸盐浓度在2~50 μmol/dm3内的天然海水硝酸盐氮同位素组成的测定,方法的标准偏差为±0.3×10-3。  相似文献   

四川攀西地区钒钛磁铁矿成矿元素富集过程模拟与资源潜力评价     

刘才泽  秦建华  李明雄  张启明 《吉林大学学报(地球科学版)》2013,43(3):758-764,775

根据层状含钒钛磁铁矿岩体的韵律特征及其铁质量分数变化规律,探索性地应用瑞利分馏模型模拟四川攀西地区攀枝花、红格、白马、太和等岩体成矿元素富集过程,分别建立了各岩体的统计模型和理想模型,并据此估算了铁矿石以及伴生钒、钛资源量。其中:攀枝花、红格、太和等岩体的数学模型比较一致,可能与这些岩体岩浆结晶分异比较彻底、成矿性好有关;而白马岩体的模型参数有较大差异,充分体现了该岩体结晶分异不彻底、成矿性相对较差的特点。  相似文献   

稠油油藏井间泥岩夹层对双水平井SAGD开发效果的影响     

唐帅  刘鹏程  潘莉莉  吴永彬  张金川 《现代地质》2016,30(2):388-393

为定量描述稠油油藏蒸汽辅助重力泄油(SAGD)开采过程中注采井间夹层对双水平井泄油通道与开发效果的影响,针对新疆油田A区块,利用CMG数值模拟软件建立了表征SAGD注采井间夹层的数值模拟模型,对注采井间存在不同大小、间距及物性夹层情况下的SAGD蒸汽腔发育形态与开发效果进行对比,得到了稠油油藏夹层非均质影响SAGD开发的临界特征参数。矿场实际的非均质SAGD井组夹层展布特征、蒸汽腔发育特征及生产效果对比结果表明,得到的结论与矿场实践一致,因此可用于指导并实现经济、高效的稠油油藏双水平井SAGD开发。  相似文献   

流水下切的动力学机制、物理侵蚀过程和影响因素:评述和展望   总被引：17，自引：11，他引：6  

程绍平  邓起东  李传友  杨桂枝 《第四纪研究》2004,24(4):421-429

流水下切是指河流河道在基岩中的垂直切割。自20世纪90年代以来,由于对全球尺度的气候、地表过程和构造之间相互作用的认识,以及工程建设和天然资源管理决策的需要,流水下切成为构造地貌学的理论研究前缘。文章从动力学机制、物理侵蚀过程、三大外来变量构造、气候和基准面变化的影响,以及区分这些变量影响的可能性等方面,对流水下切研究的最新进展予以评述。未来流水下切研究要在流水动力学和地球动力学两方面探索更多的科学问题  相似文献   

注蒸汽开采冻土区天然气水合物数值计算与野外应用          下载免费PDF全文

李宽  张永勤  孙友宏  郭威  李冰 《探矿工程》2014,41(5):14-16

试开采研究是天然气水合物从理论研究走向商业化开采的必经之路。提出的注蒸汽开采是一种综合开采方法,是在降压开采的基础上,往孔内注入热蒸汽对水合物目标开采层进行激振往复式热激发。注蒸汽开采能够避免“自保护效应”,促进水合物进一步分解,理论上能够扩大开采范围、提高产气量。利用FLUENT数值模拟软件对蒸汽加热水合物层动态过程进行数值计算,通过模拟计算结果对比分析,在满足开采要求的前提下确定最佳的注蒸汽功率为20 kW,注热时长为38 h。在青海木里盆地天然气水合物试采项目中,注蒸汽开采进行了5.2 h开采试验,产气量为3.25 m3。  相似文献   

超稠油油藏溶剂辅助蒸汽重力泄油室内实验研究     

王连刚  石兰香  袁哲  李秀峦  刘鹏程 《现代地质》2018,32(6):1203

以国内某超稠油油藏为基础,应用二维物理模拟装置开展了蒸汽辅助重力泄油(SAGD)对比实验,研究了溶剂辅助SAGD技术对SAGD蒸汽腔发育特征、原油产量以及采收率的影响。研究结果表明,溶剂辅助SAGD中,溶剂以液相和气相共同存于油藏中,溶剂浓度越高,气相组分含量越高;溶剂中的气相组分在油藏中可以减少蒸汽在上覆岩层的热损失,提高蒸汽腔垂向扩展均匀性;合理溶剂浓度下,溶剂辅助SAGD可以显著提高峰值产量;低浓度溶剂辅助SAGD的单位原油产量的能耗明显低于纯蒸汽SAGD。实验结果表明,低浓度溶剂辅助SAGD对于开采超稠油油藏具有较大的应用潜力。  相似文献   

低温多效蒸馏海水淡化技术   总被引：12，自引：0，他引：12  

尹建华  吕庆春  阮国岭 《海洋技术学报》2002,21(4):22-26

文章介绍了低温多效海水淡化技术的原理、技术优势和应用方式。并比较了几种主要海水淡化技术的投资、运行费用及技术性能。最后分析了低温多效海水淡化技术的发展趋势 ,提出设备规模大型化、采用新材料新工艺、和可再生能源及新能源的结合如低温核反应堆是低温多效海水淡化技术未来的发展方向  相似文献   

Traveling waves in a finite condensation rate model for steam injection     

J. Bruining  C. J. van Duijn 《Computational Geosciences》2006,10(4):373-387

Steam drive recovery of oil is an economical way of producing oil even in times of low oil prices and is used worldwide. This paper focuses on the one-dimensional setting, where steam is injected into a core initially containing oil and connate water while oil and water are produced at the other end. A three-phase (oil, water, steam) hot zone develops, which is abruptly separated from the two-phase (oil + water) cold zone by the steam condensation front. The oil, water and energy balance equations (Rankine–Hugoniot conditions) cannot uniquely solve the system of equations at the steam condensation front. In a previous study, we showed that two additional constraints follow from an analysis of the traveling wave equation representing the shock; however, within the shock, we assumed local thermodynamic equilibrium. Here we extend the previous study and include finite condensation rates; using that appropriate scaling requires that the Peclet number and the Damkohler number are of the same order of magnitude. We give a numerical proof, using a color-coding technique, that, given the capillary diffusion behavior and the rate equation, a unique solution can be obtained. It is proven analytically that the solution for large condensation rates tends to the solution obtained assuming local thermodynamic equilibrium. Computations with realistic values to describe the viscous and capillary effects show that the condensation rate can have a significant effect on the global saturation profile, e.g. the oil saturation just upstream of the steam condensation front.  相似文献   

深孔电极载体蒸馏光谱法测定化探样品中八个易挥发元素   总被引：2，自引：2，他引：2  

熊艳 《岩矿测试》2007,26(5):425-427

以碘化铵、硫酸钠、硫粉、碳粉、氧化钙、二氧化硅混合物为缓冲剂，深孔电极，截取曝光，以谱带背景作内标，一次摄谱同时测定化探样品中As、Sb、Bi、Ag、Pb、Cd、Tl、Sn等微量元素。方法精密度（RSD，n=10）为1．2％-5．0％，检出限为0．013—1．0μg／g。方法经国家一级标准物质验证，测定结果与标准值基本相符。  相似文献