双真空炉管的研制及其在岩石加热脱气气体组分测试中的应用

分析岩石矿物中的气体化学组成,可为岩石圈地幔的不同地球化学过程、地球内部氧化还原环境以及水在深部地球中的循环等研究提供重要的信息与约束条件。对岩矿样品加热使气体脱出是一种常用的实验手段,使用单石英玻璃管作为样品管,石英玻璃结构中不规则的空隙使得气体在高温下易发生扩散与渗透;由钼、钽坩埚组成的双真空炉管一般用于稀有气体同位素组成分析,较少用于气体化学组成分析,且该装置结构复杂,不易组装拆解,也易被损坏。针对以上问题,本文研制了石英玻璃与金属零件组成的双真空盛样炉管,该炉管具有体积小、易于组装、拆解和移动等特点。在相同的实验条件下与单石英玻璃管进行对照实验。根据实验结果,尤其是H_2浓度的测量结果表明:不论哪种类型的样品在500℃和950℃加热脱气时,应用本文研制的双真空盛样炉管,测量的H_2浓度均高于同等实验条件下应用单石英玻璃管测量的H_2浓度,该双真空炉管的气密性优于单石英玻璃管,有利于获得样品中更加真实的气体化学组成。     

岩石脱气微升量气体自动进样系统的研制

<正>在气体地球化学研究过程中,有时要求对气体量较多(如10ml以上)的气体中的微量成分进行定量,如天然气体;有时须要对实验产物100μl以下微升量气体中的成分进行定量,如岩石真空热解或真空机械破碎脱出气体。气体质谱仪一般工作在高真空状态,工作压强往往低于1×10-3Pa。因此,需要一个进样系统将上述气体量较多的气体或100μl以下微升量气体,转化为压强低于1×10-3Pa的气体,才能使用气体质谱     

烃源岩解析气获取新方法研究

新研制的解析气脱气集气装置,避免了前人装置的缺点,具有样品适应范围广、进样量大,真空破碎时间短、温度低,高真空脱气,无水集气等明显优势,从而确保了获取气体样品能够真实反映烃源岩解析气的地球化学特征。获取的解析气主要以烃类气体及二氧化碳气体为主,烃类气体相对百分含量最高可达到80%以上,可稳定检测出δ13C₁~δ13C₃数据,部分样品检测出δ13C₄~δ13C₅数据,所含地化信息丰富,完全满足了解析气地球化学研究和应用的需要。本次研究利用上述新的解析气实验地球化学技术,把气-源对比研究提升到一个崭新的境界,建立天然气气源直接对比的新方法和新思路,证实前人运用天然气碳同位素间接进行气源对比是科学可行的。同时,反证了新的解析气脱气集气装置的科学性和可靠性,为烃源岩解析气的研究和应用打下了科学的实验基础。
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本期文章导读

正469双真空炉管的研制及其在岩石加热脱气气体组分测试中的应用高梓涵1,2,3,李立武1,2*,王玉慧1,2,3,曹春辉1,2,贺坚1,2(1.中国科学院西北生态环境资源研究院,甘肃兰州730000;2.甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,甘肃兰州730000;3.中国科学院大学,北京100049)针对岩石矿物等固体样品中所包含的流体挥发份化学组成的分析测试,可提供多种地球化学信息,因而具有重要的研究意义。对岩矿样品加热使其脱气是一种重要的实验技术手段,但是通过此方法获得的气体     

矿物包裹体中气体成分的真空提取装置

为了得到矿物包裹体中气体成分的定量数据,对不同类型矿物包裹体中气体成分的提取是目前需要解决的关健问题。我们于1981年底研制了“真空热爆裂和真空研磨提取装置”,并建立了“真空热爆裂提取-气相色谱测定”和“真空研唐提取-气相色谱测定”方法,解决了不同类型矿物包裹体中气体成分的提取与测定问题。     

金在气相中迁移与有机质演化生烃关系的实验研究

火山喷气沉积物中微米级金的发现、化探地气测量检测出金等现象表明 ,在自然界金可在气相内存在。但是金以何种形式存在及其迁移机理尚待探讨。本项研究选取并制备了有地质意义的含硫有机金属化合物———烷基硫醇衍生纳米金 ,将其添加至含有机物质的自然样品中 ,在专门设计的真空加热装置中用泡塑收集其在不同温度条件下的气相产物 ,分析对比实验中产生的气相带出金的含量和气体成分 ,并与金的氯金酸水溶液作用过的样品进行对比。模拟与有机质密切相关的金在气相中迁移的地质过程。实验结果表明 ,含十二烷基硫醇衍生纳米金样品及其纯物质在升高温度条件下的气相产物带出金高于同样条件下用氯金酸处理过的含金样品。金的迁移与升高温度时产生的烃类气体有关。该实验为与有机质演化生烃有关的金气相迁移成矿过程提供了实验依据 ,由于十二烷基硫醇衍生纳米金中纳米金团簇是稳定存在于烷基硫醇结构内 ,因而实验也说明了金的纳米簇团迁移与有机质之间的密切关联。与有机质及其气相演化产物密切相关的金的气相迁移 ,是金在自然界呈气相迁移的重要形式之一。     

瓦斯样品中气体成分分析

将野外装入解吸罐中的煤芯样,用真空脱气装置脱气,脱出的气体通过GC4008B气相色谱仪进行组份浓度测定,记录的数据经A5000气相色谱工作站数据处理软件处理。从而快速、准确地测定出CO、CO2、CH4、C2H4、C2H6、C3H8以及重烃等气体成分的含量。用于大批量实际样品测定,符合质量管理的要求。     

气体快速监测系统的组建及其在漠河冻土区天然气水合物钻探工程MK-2孔中的应用

本文结合非动力型脱气器与动力型脱气器的优点,研制出一种适用于低流量、低流速等小型钻探工程的飞溅离心式钻井泥浆脱气设备,并组建一套陆域天然气水合物钻井气体的快速监测系统。此套系统中,钻井泥浆在脱气筒内自动采集气体并将气体样本通过导管引入实验室,通过阀切换、多柱分离、双检测器的气相色谱分析系统,可同时检测C_H__4、C_2H__6、C_2H_4、C_3H_8、C_3H_6、n-C_4H_(10)、i-C_4H_(10)、n-C_5H_(12)、i-C_5H_(12)、O_2、N_2、C_O2、CO等多种气体。其中,烃类气体的方法检出限为0.10~1.00μL/L,非烃气体的检出限为100μL/L~0.01%,方法精密度为1.65%~11.6%,样品分析周期约10min。该系统通过在黑龙江省漠河盆地开展的东北冻土区天然气水合物科学钻探工程MK-2孔的试运行,实现了钻井气体的在线快速监测,方法灵敏、稳定可靠,具有较好的精密度和较低的检出限,能够基本满足天然气水合物等气体钻探现场检测的需要。     

新型沙漠土壤水分真空抽提装置的研制与应用

稳定同位素分析技术是解译干旱-半干旱区沙漠土壤水分运动信息的较好工具。该技术难点不是同位素测试本身,而是用于同位素分析的土壤水分抽提。针对这一难点,本研究对传统抽提装置进行改进。改进型土壤水分抽提装置为支路并联玻璃管路结构,采用真空抽提和液氮冷凝结合收集土壤水分。新装置工作时真空度高且稳定,由实验室原装置的5 Pa提高到0.5 Pa,水分抽提回收率接近100%;其样品装载最多可达600 g,水分收集最大容量为15 mL,显著优于国外典型装置。条件实验显示,相应水分同位素δ值的标准偏差<1‰,表明新装置性能良好,满足测试要求;105℃条件下沙漠水分真空蒸馏抽提时间最少只需要20min,就能保证水分的充分收集及其同位素没有明显分馏。新型装置的显著特点是适合不同湿度类型、不同质量的样品抽提,且水分抽提回收率高,还具有造价低廉、操作灵活及易维护等特点,与实验室原装置相比,工作效率提高了一倍。野外沙样土壤水分抽提实验及其同位素分析进一步证实了改进型新装置在同位素水文研究中具有重要的应用价值。     

岩石热脱气单体碳／氢同位素组成分析装置

研制了一套岩石热脱气装置，并将它与稳定同位素比质谱计连接，实现了岩石吸附气或包裹体气的单体碳、氢同位素组成分析。该装置的加热温度可达1100℃。样品收集过程中碳同位素基本不发生分馏。碳同位素组成测量结果的标准偏差≤1．1‰，氢同位素组成测量结果的标准偏差≤9‰。     

Formation of Pt-bearing Western Pana pluton on the Kola Peninsula: Fluid regime as deduced from helium and argon isotopic compositions

The distribution of He and Ar isotopes has been studied in 41 rock samples and seven monomineralic fractions from ore-bearing layered units and poorly differentiated host gabbronorite of the Western Pana mafic–ultramafic pluton on the Kola Peninsula. The gases assigned for mass-spectrometric analysis were released by means of whole-rock sample melting and by comminution mainly from fluid microinclusions. The data show that the present-day isotopic composition of noble gases in rocks from the pluton is caused by many factors: the degree of melt degassing, various concentrations and retention of the trapped isotopes, the contents of radioactive elements, and the generation and loss of radiogenic gases. The hypabyssal conditions of pluton formation facilitate the loss of primary mantle-derived volatile components and the dilution of magmatic fluid with near-surface paleometeoric waters containing air dissolved therein. The correlation of noble gas isotopes and ore-forming chemical elements does not suggest derivation of the latter from crustal material and evidences their mantle origin. Variations in the geochemical indices of the gas corroborate previously established or proposed multistage formation of the pluton, mainly, the autometamorphic character of postmagmatic processes and the participation of fluids in ore formation.     

Volcanic degassing at Somma–Vesuvio (Italy) inferred by chemical and isotopic signatures of groundwater

A geochemical model is proposed for water evolution at Somma–Vesuvio, based on the chemical and isotopic composition of groundwaters, submarine gas emission and chemical composition of the dissolved gases. The active degassing processes, present in the highest part of the volcano edifice, strongly influence the groundwater evolution. The geological–volcanological setting of the volcano forces the waters infiltrating at Somma–Vesuvio caldera, enriched in volcanic gases, to flow towards the southern sector to an area of high pCO₂ groundwaters. Reaction path modelling applied to this conceptual model, involving gas–water–rock interaction, highlights an intense degassing process in the aquifer controlling the chemical and isotopic composition of dissolved gases, total dissolved inorganic C (TDIC) and submarine gas emission. Mapping of TDIC shows a unique area of high values situated SSE of Vesuvio volcano with an average TDIC value of 0.039 mol/L, i.e., one order of magnitude higher than groundwaters from other sectors of the volcano. On the basis of TDIC values, the amount of CO₂ transported by Vesuvio groundwaters was estimated at about 150 t/d. This estimate does not take into account the fraction of gas loss by degassing, however, it represents a relevant part of the CO₂ emitted in this quiescent period by the Vesuvio volcanic system, being of the same order of magnitude as the CO₂ diffusely degassed from the crater area.     

Innovation of experimental methodology for adsorbed gases on hydrocarbon-source rocks

As compared to the device developed by our predecessors, the newly developed adsorbed gas degasification-collection device has a series of advantages such as wide sample application range, large sample inlet, high vacuum, short-time sample smashing, low crushing temperature and water-free gas collection, which ensure the geochemical characteristics of acquired adsorbed gas samples to be the same as those of the adsorbed gases on corresponding hydrocarbon-source rocks. The results showed that the acquired adsorbed gases are composed mainly of hydrocarbon gas and carbon dioxide gas, with the hydrocarbon gas accounting for more than 80%, and can be measured reliably for their δ13C1-δ13C3 data, even δ13C4-δ13C5 data. The results of carbon isotope test and analysis satisfy the needs for the geochemical study and application of adsorbed gases. The above new techniques of experimental geochemistry are helpful for establishing the new direct natural gas-source correlation method, proving that the previous usual method of indirect natural gas-source correlation is scientific and authentic, thus providing the experimental basis for the study and application of adsorbed gases on hydrocarbon-source rocks.     

Genesis of the mineral groundwaters of the Razdol’nenskii occurrence in Primorye

Original isotopic and chemical data are reported on the groundwater and gases from the unique occurrence of mineral water in the coastal zone of southern Primorye. Results of the δ¹⁸O and δ²H analysis of the underground and surface water of the area integrated with their δ¹³C composition made it possible to solve the problem of the genesis and evolution of groundwater and gases in the coastal part of the Sea of Japan. It was established that meteoric waters penetrate into the Mesozoic terrigenous rocks and changed their chemical composition under the influence of transformation of organic matter from the host rocks. CO₂ released owing to reactions provides multiple enrichment of the water in HCO₃ and stimulates Na influx via dissolution of aluminosilicates.     

陆地水热系统气体地球化学研究进展

地表水热活动常伴有通量不等的气体释放，作为水-岩反应和地球深部脱气的产物，泉气的化学和同位素组成因其热储所处的大地构造单元、岩性和应力状态的差异而有所不同。对泉气化学和同位素组成时空变化的观测和研究是了解地壳-岩石圈动力学的重要方面，有助于地震、火山活动等地质灾害的监测和地热资源的开发利用。     

天然气运移的气体组分的地球化学示踪

本文通过我国不同含油气盆地典型地区岩石酸解气、罐顶气和天然气中化学组分分析,结合天然气的形成和盆地的地质演化,研究了天然气运移时组分的变化。结果表明,天然气通过地层孔隙系统运移时,组分会发生明显分馏,表现在甲烷相对重烃、异构丁烷相对正构丁烷的优先迁移。酸解气、罐顶气和成藏天然气中C₁/C₂+、iC₄/nC₄及总烃/非烃等比值,是天然气运移示踪的有效指标。     

Free hydrogen-hydrocarbon gases from the Lovozero loparite deposit (Kola Peninsula,NW Russia)

The Lovozero nepheline-syenite massif in the north-eastern Fennoscandian Shield, well-known to mineralogists and petrologists, is also interesting with its high contents of hydrogen-hydrocarbon gases in different forms of presence, which is untypical of magmatic rocks. The article systematizes and generalizes little known and unpublished data on the composition, location, character and scale (intensity) of the free gases (FG) emission within a major loparite deposit confined to the massif. СН₄ and Н₂ are dominant in the FG composition. The molecular weight distribution of hydrocarbon gas components corresponds to the classic Anderson–Schulz–Flory distribution with a steep gradient. Carbon and hydrogen of the gases are characterized by rather heavy isotope compositions, becoming lighter from the transition of methane to ethane. The FG volume has been estimated as 0.2–1.6 m³ of gas per 1 m³ of undisturbed rock. The gas recovery of walls in underground workings has been up to 0.2 ml/min/m² for СН₄ and 0.5 ml/min/m² for Н₂ in several years after their heading. The discharge of some shot holes that characterizes the gas emission intensity (1.8–2 m deep and 40 mm in diameter) is up to 300 ml/min, but its 1–2 orders lesser values dominate. The discharge time in some sections varies from several days to 20 years. The overpressure of gases towards the air mainly does not increase 100 hPa, sometimes reaching 120 kPa. It has been defined, that FG distribute irregularly (at the distance of centimeters to hundreds of meters) and their composition and particularly emission intensity perform different temporal fluctuations. The abiogenic origin of FG has been proposed, with FG appearing as a mixture of gases in various proportions: (a) gases remaining in microfissures at the massif's consolidation after the capture by fluid inclusions and those lost during degassing and (b) gases occurred in mechanic-chemical reactions, partial emission and concentration of occluded and diffusely scattered gases under the unstable stress-strain mode of the rock mass. Combustible and explosive hydrogen-hydrocarbon FG can accumulate in the air of underground workings and cause accidents, disrupting the workflow. The background for using characteristics of spatial-temporal variations of the FG emission as precursors of dangerous geodynamic phenomena has been indicated.     

松辽盆地北部火山岩CO2脱气参数及其对CO2资源量估算的意义

为了定量评价火山岩脱CO2气量的潜力，选择松辽盆地北部火山岩进行了低温脱气实验。将火山岩加热到250℃时，脱出挥发份总量为0.0299～0.0790ml/g；其中CO2脱出量为0.0218～0.0706 ml/g（0.429～1.387wt％）。脱挥发份总量与其中CO2量具有良好的正线性相关；挥发份以CO2气为主，其次是Ｎ2气，还伴有H2、CO、CH4等还原性气体，以及更少量的低碳烷烃；基性火山岩比中、酸性火山岩脱出CO2数量较多。火山岩吸附大量CO2气，成为充足气源，火山岩脱出的吸附气主要是辗转而来的深源气，火山岩成为探索幔源气成藏的主要源岩，尤其是基性火山岩。估算CO2资源量，可将250℃时火山岩挥发份含量作为岩石挥发份及残余CO2量的下限值，而全岩分析的总碳含量可作为CO2脱出量的上限值。     

Geochemistry of reduced gas related to serpentinization of the Zambales ophiolite, Philippines

Methane-hydrogen gas seeps with mantle-like C and noble gas isotopic characteristics issue from partially serpentinized ultramafic rocks in the Zambales ophiolite, Philippines. New measurements of noble gas and ¹⁴C isotope abundances, rock/mixed-volatile equilibrium calculations, and previous chemical and isotopic data suggest that these reduced gases are products of periodotite hydration. The gas seeps are produced in rock-dominated zones of serpentinization, and similar gases may be ubiquitous in ultramafic terranes undergoing serpentinization.     

深部物质运动的气体地球化学特征

根据氦同位素地球化学资料讨论了中国东部和云南腾冲地区上地幔的脱气。尽管地球脱气作用主要发生在地球形成时的十亿年间，但是后期的脱气作用仍是影响大气圈演化的主要因素。在两种力学性质不同的构造带──中国东部大陆裂谷和位于欧亚板块与印度板块缝合带的腾冲火山区，采集了天然气样，并分析了气体组分和氦同位素组成，较高的３Ｈｅ／４Ｈｅ值和地质、地球物理资料表明天然气和温泉气中的氦相当一部分是来自上地幔。来自上地幔的氦和其他气体自第三纪以来不断在气藏中聚集或向大气中逃逸。伴有源于上地幔的岩浆活动的地幔脱气是深部物质运动的具体表现形式，它对新生代气候演变可能有直接影响。