芳烃分析在油气化探中的作用和意义

三维荧光光谱具有指纹特征,分析钻井岩屑的荧光光谱,可以判别是否含油气或煤;分析油气样品的固定波长同步荧光光谱,可以推断油气是海相或陆相成因;根据荧光光谱的非油气特征,可以辩识污染或干扰.恒定能量同步荧光光谱技术能够消除拉曼光干扰,用于芳烃及石油分析,优于固定波长同步荧光光谱,是油气化探中有应用前途的方法.     

荧光分析法在油气化探中的应用

荧光光谱法是分析芳烃的灵敏、快速、高效的方法,通过样品的同步荧光光谱和三维荧光光谱特征,可以进行油气属性的判断;区别油气信息和煤信息,区分油气信息和泥浆污染信息,提高钻井预测的准确度。某些情况下,可以用简单、便捷的同步荧光光谱取代三维荧光光谱分析,达到事半功倍的效果。     

油气勘探荧光光谱法在土壤与其上方积雪的对比实验

荧光光谱法是多环芳烃分析常用的方法,可以判定油气运移及地下原油属性。新疆位于我国西部,冬天积雪覆盖,根据它的地理气候环境,结合荧光光谱法的检测限低,灵敏度高等特点,在新疆某已知油区的一条剖面上,对积雪及其下方土壤进行荧光光谱法分析,主要从二维荧光光谱、固定波长同步荧光光谱、三维荧光光谱的分析结果进行对比,发现积雪对稠环芳烃存在较好的吸附作用,对地下油气藏也有较好的异常指示。     

油气化探同步荧光技术中的若干问题

在试验的基础上,对油气化探固定波长同步荧光测试技术中光谱图的认识、波长差与方法灵敏度的关系以及同步荧光与其他荧光方法的内在关系等问题作了深入的研究和探讨,澄清了该技术在实际应用工作中较易产生混淆的几个问题,旨在推动该项技术在油气化探工作中的进一步应用和发展.     

利用三维荧光技术判识油气属性

芳烃是原油和生油岩中重要的组成部分,芳烃化合物较为复杂、稳定,可用来进行油源对比及油气属性的鉴别,是油气化探指示油气存在及油气属性的主要指标.三维荧光图谱具有“指纹图”的特征,不同性质的样品,其三维荧光光谱的各特征参量存在明显的差异,而同源样品,其参量又存在着较大程度的共性.通过对某探区近地表土壤样品的三维荧光分析表明,三维荧光光谱对油气属性具有较好的指示作用,据其可推断下覆圈闭的含油气性质,是地面化探研究油气运移及指示油气属性的有效指标.     

近地表荧光光谱特征及其与烃源岩关系初探--以合肥盆地为例

合肥盆地是我国东部油气勘探程度很低的沉积盆地.首次应用同步荧光和三维荧光技术方法在近地表检测芳烃化合物,通过主峰位置、峰匹配特征、荧光强度及二维图形特征等参数,结合地质、地球物理及钻井烃源岩资料,研究荧光光谱分类与分布特征,预测本区发育有下古生界、上古生界、中一新生界三套性质有别的烃源岩及其空间分布范围,为油气勘探提供了信息.     

以PC1井三维荧光光谱分析结果论油气垂向运移

本文以Pcl并不同深度岩心和地表土壤作为分析样品，通过三维全扫描荧光光谱等分析。揭示了该区油气垂向运移规律和地下油气的某些分布特征。研究表明，芳烃三维荧光光谱方法是研究芳烃组成变化最理想的手段之一，可以有效地解决油气运移等问题。     

山东蒙阴钻石的三维荧光光谱特征及其与紫外荧光特征的对比

三维荧光光谱是20世纪80年代发展起来的一种新的荧光分析技术,其与紫外荧光光谱相比,前者能获得激发波长和发射波长同时变化时的荧光强度信息,在多组分混合物的定性与定量分析、在环境、生物、化学等方面的应用较成熟,而在珠宝玉石的测试与研究中则应用较少。选取山东蒙阴矿区产出的25颗钻石样品作为研究对象,采用三维荧光和紫外荧光对其进行了测试与分析。结果表明,该钻石样品的三维荧光光谱特征可分为无荧光谱峰、单荧光谱峰、双荧光谱峰和3个荧光谱峰4种类型,与其紫外荧光特征呈一一对应关系。     

利用油包裹体微束荧光光谱判识油气充注期次

基于石油的荧光性, 通过常规荧光光谱方法, 对油包裹体的荧光光谱进行定量化描述, 利用其主峰波长、最大荧光强度及红/绿商等属性参数, 根据主峰波长与最大荧光强度、主峰波长与红/绿商的相关关系特征, 可以便捷而有效地开展油气充注期次的判识.民丰洼陷沙三段岩性油气藏储层的15块流体包裹体样品检测结果表明, 发黄色荧光的油包裹体荧光光谱结构和形态相似, 其主峰波长一致; 而发蓝白色荧光的油包裹体荧光光谱具有2种类型: 一类与黄色荧光油包裹体荧光光谱结构和形态相似, 主峰波长一致, 表现出同源特征; 另一类明显发生"蓝移", 表现出异源特征.主峰波长与最大荧光强度, 以及主峰波长与红/绿商的相关关系均表现出3种特征类型.因此, 可判定民丰洼陷沙三段岩性油气藏在其地质历史时期共经历了3期油气充注.      

塔里木盆地北部油气地球化学特征及异常成因探讨

为了发挥油气化探“迅速掌握全局快速缩小靶区”的战略性作用，服务油气化探全国扫面计划，选择塔里木含油气盆地北部开展低密度（1点/25km2）油气地球化学填图试点。油气化探填图指标土壤酸解烃、顶空气轻烃、荧光光谱、紫外吸收光谱和蚀变碳酸盐在大型油气田、油气富集区带上方均发育地球化学省异常，异常平面空间分布与地下油气富集区带具有良好的套合关系，对油气富集具有指示意义。区域性的荧光光谱等指标异常浓集中心沿轮台断裂等主干断裂带分布，与地下断裂位置良好的匹配性指示了油气大规模的运聚。甲烷碳同位素证实研究区油气地球化学省异常成因为热解成因，土壤样品三维荧光光谱发育共性峰，三维荧光光谱指纹特征反映了近地表土壤烃类异常与地下油气运移和油气藏类型相关。塔里木盆地北部地区油气地球化学填图试点结果表明，大型盆地可以采用甚低密度油气地球化学填图技术，圈出寻找大、中型油气田和油气富集区带的异常区，发挥油气化探“迅速掌握全局快速缩小靶区”的战略性作用。     

6种不同产地柯巴树脂的谱学特征探究

收集了来自俄罗斯、新西兰、婆罗洲、马达加斯加、哥伦比亚和苏门答腊6个不同产地的柯巴树脂,采用宝石显微镜、红外光谱、紫外荧光观察和三维荧光光谱等测试方法对柯巴树脂谱学特征进行了对比研究。婆罗洲、苏门答腊柯巴树脂的红外光谱主要特征为存在3000~2800 cm^-1范围内4个吸收峰,1732 cm^-1肩峰和1708 cm^-1吸收峰,888 cm^-1处的弱吸收峰。新西兰柯巴树脂红外光谱主要特征为存在3000~2800 cm^-1范围内3个吸收峰,1642 cm^-1和888 cm^-1处的弱吸收峰。马达加斯加、哥伦比亚和俄罗斯柯巴树脂的红外光谱相似,主要特征为存在与C=C相关的3处组合特征吸收峰以及1270 cm^-1和1180 cm^-1处的2个吸收峰。在长波紫外荧光下,婆罗洲和新西兰柯巴树脂荧光强度明显强于其他产地样品,马达加斯加柯巴树脂荧光强度最弱。由三维荧光光谱可知,婆罗洲和苏门答腊柯巴树脂中存在445、474、505 nm 3个发射峰,可被416、447 nm波长有效激发;新西兰柯巴树脂的最强发射峰位于385 nm,其最佳激发波长352 nm;俄罗斯柯巴树脂最强发射峰在399 nm,可被354 nm波长最佳激发;哥伦比亚柯巴树脂的最强发射峰为470 nm,被400 nm波长最佳激发;马达加斯加柯巴树脂的最强荧光峰在465 nm,被378 nm波长最佳激发。综合分析认为,三维荧光光谱特征和红外光谱特征可为柯巴树脂的鉴别和分类提供依据。     

Fluorescence excitation-emission matrix characterization of a commercial humic acid

Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0-0.05 moL/L KClO4 ) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100mg/L) of FHA and pH (2-12 ) had significant effects. A red shift in the longer wavelength peak region was observed when the coneentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH = 5.0. The protonation constants ( lgK^ HL ) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r(A/B) values range from 0.61 to 2.59. A strong linear relationship between r(A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.     

Fluorescence micro-spectrometry of synthetic and natural hydrocarbon fluid inclusions: crude oil chemistry,density and application to petroleum migration

The fluorescence spectra of crude oils, synthesized as hydrocarbon fluid inclusions (hcfi) in NaCI crystals, have been recorded and correlated with crude oil chemical analysis. The crude oils represent a wide range in total hydrocarbons, saturate and aromatic fractions, and resin-asphaltene concentration. The fluorescence properties (Lambda max and Q) of the hydrocarbon fluid inclusions display a systematic red shift to longer wavelengths from 440 nm to 595 nm with increasing aromatic content and increasing concentration of NSO-bearing compounds. A positive correlation also exists between Lmax-Q and the thermal maturity parameters nC17/pristane and nC₁₈/phytane. First order linear regression equations provide a method for constraining the chemical composition of natural hydrocarbon fluid inclusions. Lmax and Q correlate positively with oil density (°API), providing for an indirect method of estimating the API of a natural hydrocarbon fluid inclusion assemblage. Fluorescence spectra of non-biodegraded crude oils from the Upper Devonian Birdbear Formation, Saskatchewan, Canada, have been correlated with regionally widespread hcfi within carbonate carrier beds and reservoir rocks of the same formation. The two most dominant types of hcfi spectra match well with the fluorescence spectra from crude oils within the Birdbear Formation. A third, less common population of very-blue fluorescing hcfi (Lmax=415440 nm, Q ≤ 0.10) also occur within fractures, intercrystalfne cements or in fossil overgrowths. The Lmax-Q-API-chemical correlations establised for the synthetic hcfi suggests that the °API of these inclusions is probably > 45° and the saturate/aromatic ratio ranges from 3.2 to 5.1. Spectra from hcfi within quartz overgrowths and cements, fractures and carbonate cements from sandstone reservoirs in the Jeanne d'Arc Basin offshore Newfoundland, compared with fluorescence spectra of crude oils suggests that some of the reservoirs may have been filled by a relatively low maturity oil and then a higher maturity oil. This is reflected in the intermediate spectra of the crude oils relative to the spectra of two separate hcfi events. Other reservoirs appear to have been charged with a relatively high gravity oil which was later biodegraded. This is marked by a blue region spectra for the hcfi compared with a red-shifted spectra for the crude oil (°API = 19). The API of the original unaltered oil which charged the reservoir is estimated to be between 32 and 38° using the Lmax-Q-API relationship established for the synthetic hcfi.     

Geochemical constraints on mixed source and hydrocarbon filling process in the Yingjisu Sag,Tarim Basin,Xinjiang

The Yingjisu Sag was petroliferous for normal oil, condensate oil, reservoir bitumen and natural gases. Geochemical studies showed that natural gases in the Yingjisu Sag were a gas mixture consisting mainly of Cambrian pyrolysis gas, Jurassic condensate oil in well Yingnan 2 and normal oil in well Tadong 2, reflecting the characteristics of marine-phase gases and oils, while crude oils in well Longkou 1 demonstrated the characteristics of both marine and terrestrial oils, which were derived from lower algae and higher plants. Jurassic oils from wells Longkou 1 and Huayingcan 1 and Cambrian crude oils from well Tadong 2 were derived mainly from Cambrian-Lower Ordovician source rocks. Jurassic and Silurian reservoir bitumens from well Yingnan 2 were biodegradated, suggesting they are of marine and terrestrial origins. The bitumens have similar geochemical characteristics, which are correlated well with Ordovician crude oils from well Tadong 2 and Jurassic condensate oil from well Yingnan 2. Based on the characteristics of tectonic evolution in this area and the analysis of hydrocarbon accumulation, the constraints on the mixed source and hydrocarbon filling process in the Yingjisu Sag were brought forward.     

Detection of organic biomarkers in crude oils using ToF-SIMS

In this study, we show that time of flight-secondary ion mass spectrometry (ToF-SIMS) can be used to detect organic biomarkers, such as hopanes and steranes, in non-fractionated crude oils, without extraction and chemical preparation. Hopanes and steranes may provide valuable information on the history of life on early Earth, particularly if they are present in fluid inclusions in ancient rocks. Due to the presence of different generations of inclusions in even very small rock samples, it would be advantageous to find a method capable of detecting biomarkers in single oil rich fluid inclusions. The capability of ToF-SIMS for detailed chemical analysis of very small sample amounts makes it a potential technique for such analysis, and in this work this possibility is explored. The presence of hopanes and steranes in four different crude oils of different ages and stages of biodegradation was investigated using ToF-SIMS and GC–MS. By combining analyses of biomarker standards, crude oils and chromatographic oil fractions, specific peaks for the different biomarkers were identified in the ToF-SIMS spectra. The presence of these peaks in the spectra from the crude oil samples could be attributed to the biomarkers based on exact mass determination and by comparison with the spectra from the biomarker containing and biomarker lacking fractions, respectively. In addition, the results show that a significant biomarker signal may be obtained from a 10 μm² oil sample, demonstrating the potential of ToF-SIMS for analysis of single oil bearing fluid inclusions, which in turn may contribute to a better understanding of the early history of life on Earth.     

Simulation of the fluorescence evolution of “live” oils from kerogens in a diamond anvil cell: Application to inclusion oils in terms of maturity and source

The evolution of fluorescence has been measured for “live” oils generated from 14 oil-prone kerogens or coals from varying depositional environments during closed system pyrolysis in a diamond anvil cell at three heating rates (3, 8, and 25 °C/min), and temperatures up to 600 °C. The measured fluorescence intensities of the samples, employing using violet excitation at 405 nm, increases significantly during maturation intervals within the oil window, while the fluorescence spectra of oils generated from all studied kerogens exhibit progressive blue-shift of peak wavelengths (λ_max) and red/green quotients (I₆₅₀/I₅₀₀) upon increasing maturity. The observed trend is consistent with a maturity dependence of the spectral shift, which is widely recognized in natural hydrocarbon inclusions and crude oils using ultraviolet (UV) excitation (365 nm). The data presented herein suggest that the λ_max of spectra for inclusion oils shift in similar direction despite differences in composition or source kerogen. This implies that the reverse or anomalous trends reported for inclusion oils in nature may be attributed to other processes, which significantly alters the fluorescence properties of oils subsequent to their generation. Oils with the similar color (λ_max or I₆₅₀/I₅₀₀) can be derived from diverse kerogens with maturities that vary by ±0.3% Ro, suggesting that the fluorescent colors of crude and inclusion oils are both maturity- and source-dependent, and therefore cannot be used as universal maturity indicators. In addition, the blue-shifts observed for cumulative oils generated from all kerogens approaches similar minima λ_max values around the green-yellow wavelength (564 nm) and at I₆₅₀/I₅₀₀ values around 0.6, at maturities close to the middle or late stage of oil generation. This suggests that most late-stage cumulative oils will exhibit similar colors. Oils generated during late-stage maturity intervals, however, can exhibit colors with shorter wavelengths.     

CONTRIBUTION TO THE GEOCHEMISTRY OF CRUDE OILS AND GASES FROM THE MUD VOLCANO ZONE OF THE KEYMIR-CHIKISHLYAR AREA OF WESTERN TURKMENIA

The paper describes crude oils and gases from mud volcanoes and oils and gases from producing horizons at depth in the same area. It is shown that the mud volcano gases and oils (the oils particularly) can be correlated with those in strata from 500 m. to more than 2,600 m deep. The mud volcano gases are somewhat modified by hypergene processes. Analytical data in tabular form is given.--B. W. Nelson.