Distribution of petroleum hydrocarbons and organochlorinated contaminants in marine biota and coastal sediments from the ROPME Sea Area during 2005

The composition and spatial distribution of various petroleum hydrocarbons (PHs), comprising both aliphatic and polycyclic aromatic hydrocarbons (PAHs), and selected chlorinated pesticides and PCBs were measured in biota and coastal sediments from seven countries in the Persian Gulf and the Gulf of Oman (Bahrain, Iran, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates). Evidence of extensive marine contamination with respect to organochlorinated compounds and PHs was not observed. Only one site, namely the BAPCO oil refinery in Bahrain, was considered to be chronically contaminated. Comparison of the results from this survey for Σ DDTs and Σ PCBs in rock oysters from the Gulf of Oman with similar measurements made at the same locations over the past two decades indicates a temporal trend of overall decreasing Σ PCB concentrations in oysters, whereas Σ DDTs levels have little changed during that period.     

Organochlorine contamination (PCBs, DDTs, HCB, HCHs) in sediments from Cienfuegos bay, Cuba

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments from Cienfuegos bay, Cuba. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the residual waters of the city and thermoelectrical power approached the sediment quality guidelines for PCBs and DDTs. Relatively higher ΣDDT concentrations and high DDT/DDE + DDD ratios in two sites near the outfalls of the city indicated a current DDT usage, probably linked to public health emergencies. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment.     

东海盆地西湖凹陷凝析油和轻质油生源母质剖析

东海盆地西湖凹陷所分析的原油样品主要为凝析油和轻质油,黄岩构造带与平湖斜坡带原油的生源母质特征存在明显区别:黄岩构造带原油中C29甾烷占优势,C27、C28甾烷有一定含量,表明母质以陆源高等植物为主,水生生物占一定比例的贡献,二萜类化合物中富含源于裸子植物针叶树脂的成分,原油Pr/Ph值大于5.0,富含升补身烷和重排补身烷,表明其来自富含黏土、沉积环境呈氧化性的泥岩或煤系烃源岩;平湖斜坡带原油中C29甾烷占明显优势,母质中陆源高等植物占重要比例,二萜类化合物中富含源于裸子植物松柏目树脂的成分,原油Pr/Ph值大部分大于4.0,其富含补身烷,重排补身烷含量变化较大,表明原油母质主要形成于氧化环境,源岩岩性有所区别。两个构造带原油均已成熟,但成熟度略有不同。     

Petrological and Organic Geochemical Characteristics of Oil Sands from the Middle Jurassic Yan'an Formation in the Southern Ordos Basin,China

An integrated petrological and geochemical analysis of surface and drilled oil sands was conducted to assess the organic matter origin/type, thermal maturity and paleoenvironment. Petrographic analysis of the oil sand used to establish the relationships between porosity and permeability with bulk density, RQI, NPI and FZI. The strong correlation between reservoir quality index (RQI) and permeability (R² = 0.98) reveal that porosity has a good correlation to RQI. The biomarker signatures of the analyzed oil reveal predominance of subaquatic‐derived source input with mainly land plant materials. This was indicated based on the average concentration of αααC27:C28:C29 sterane 20R of about 38%, 22% and 40% respectively. This interpretation is also supported by high values of tricyclic terpane/αβC30 hopane and regular sterane/αβC30 hopane. An anoxic condition of deposition within a lacustrine paleoenvironment that attributed to the enhancement of the preservation of the organic matters in the area were indicated based on the low Pr/Ph ratios (average 0.74), low values of αβC31‐22R‐hopane/αβC30 hopane ratios and high C26/C25 tricyclic terpane ratios as well as the presence of gammacerane and a low water salinity. Biomarker maturity parameters show that the extracted oil sand has entered the early oil window stage.     

重砂分级-扫描电镜-能谱等技术研究湖南张家界黑色页岩贵金属元素赋存状态

黑色岩系是多种有用元素的重要载体,Cu、Pb、Zn、Ni、Mo、V、U、Au、Ag、稀有和稀土元素在黑色岩系中异常富集,某些黑色岩系的贵金属(铂族元素、Au、Ag)也异常富集,其含量甚至部分超过了基性和超基性岩,这类黑色页岩矿床中铂族元素(PGEs)的赋存状态至今尚未有一个确切的定论。本文采集了湖南张家界属寒武系牛蹄塘组黑色页岩中Mo-Ni矿层作为研究样品,通过化学分析表明矿石中含Pt 531×10~(-9),Pd 514×10~(-9),Os 185×10~(-9),PGEs合量为1259.43×10~(-9),Au 332×10~(-9),Ag 12.2×10~(-6),已富集成矿。进一步利用重砂分级、化学分析、X射线衍射、扫描电镜及能谱技术研究了贵金属元素赋存状态,结果表明:①Ag:主要以独立矿物形式存在,少量以类质同象形式赋存在其他矿物中。独立矿物有砷铜银矿、硫锑铜银矿、硫锑铅银矿、锑银矿、硫银锡矿、硫砷银铅矿、银黄锡矿、辉银矿、锑-银-锡互化物;类质同象主要是银黝铜矿-银砷黝铜矿、含银方铅矿和含银砷铜矿等。②Au:未发现独立矿物,黄铁矿是重要载金矿物。③PGEs:未见独立矿物,在不同重砂分级样品中没有富集,具分散性,推测铂族矿物很可能是以纳米形式存在,建议今后研究选矿工艺时,可考虑从制取纳米材料的思路进行应用研究。本文Ag-Sn-Sb互化物的发现为研究黑色岩系多元素富集成因机制提供了重要物证。     

湘西下寒武统含铀磷块岩中钛铀矿和晶质铀矿的发现及其成因分析

对湘西下寒武统牛蹄塘组黑色页岩系中的含铀多金属磷块岩,笔者通过α径迹法示踪,先后采用电子探针、扫描电镜及透射电镜进行成分和结构分析,首次在其中发现了微晶状的晶质铀矿、斜方钛铀矿和钛铀矿。这3种铀矿物密切共生,也与钼、镍、铅、锌、铜、钒、铁等的硫化物共生,主要赋存于多金属磷块岩的雏晶石墨中,与碳的关系密切;其次也赋存于石英和先期形成的碳硫钼矿碎片中。斜方钛铀矿呈长柱状,钛铀矿呈短柱状和粒状,晶质铀矿多呈它形粒状,少数呈八边形自形、半自形晶。矿物粒径多在1~5μm,集合体可达10~20μm。进一步的成因研究表明,钛铀矿和晶质铀矿由高温铀氢化合物海底气相喷出凝聚所形成。     

大王北洼陷烃源岩有机地球化学特征

根据烃源岩可溶抽提物的色谱和色谱- 质谱分析结果,对大王北洼陷沙四段、沙三段和沙一段烃源岩的饱和烃和芳烃生物标志化合物组合特征进行了对比研究,揭示了三套烃源岩在沉积环境和有机母源输入的不同特征,总结了应用生物标志化合物鉴别三套烃源岩的组合参数特征,为精细的油源对比奠定了基础。研究表明,沙四段烃源岩具有较低的Pr /Ph,4-甲基甾烷同类物中C28 4-甲基系列含量最低、较高的甲藻甾烷含量、较低的重排甾烷含量、异常的C35 升藿烷含量、高伽马蜡烷异常指数、含一定量的奥利烷和较高的硫芴系列化合物含量等特征,反映了沙四段烃源岩形成于高盐度含硫强还原沉积环境,低等水生生物为主,高等植物有明显贡献的混合母源特征。沙三段烃源岩具有较高的Pr /Ph,4-甲基甾烷同类物中C29 4-甲基系列含量最低、几乎不含甲藻甾烷、较高的重排甾烷含量、基本正常的升藿烷分布、低伽马蜡烷异常指数和较低的奥利烷含量等特征,反映了沙三段烃源岩形成于半咸水的一般还原环境,低等水生生物为主,有一定量高等植物有机输入的混合母源特征。沙一段烃源岩具有极低的Pr /Ph,4-甲基甾烷同类物中C28 4-甲基系列含量最低、较高的甲藻甾烷含量、很低的重排甾烷含量、异常的C33 升藿烷含量、高伽马蜡烷异常指数、极低的奥利烷含量和较高的脱羟基维生素E 含量等特征,反映了沙一段烃源岩形成于高盐度强还原沉积环境,低等水生生物占绝对优势的有机母源特征。对研究区烃源岩生物标志化合物成熟度参数随深度的变化进行了分析,结果表明在不同层系中成熟度参数的演化存在显著差异,沉积埋藏历史和沉积环境可能是导致这些差异的原因,为此在应用这些参数进行烃源岩乃至生成石油的成熟度评价时,应使用不同的标准。     

砒砂岩化学成分特征对重力侵蚀的影响

本文以内蒙南部砒砂岩的重力侵蚀为例,研究岩石化学成分与重力侵蚀发育的主要控制因素抗剪强度的之间关系。通过对砒砂岩样品的化学成分、矿物组成、力学性质等参数的测试和试验结果,利用化学蚀变指数(CIA)阐明了岩石的风化程度,分析了岩石中不稳定的化学成分在水的作用下,对岩石的化学风化作用和岩石强度的影响。并对砒砂岩的化学成分含量与其内聚力进行两两相关分析和多元相关分析。这些对砒砂岩区基岩的重力侵蚀机理研究具有一定的参考价值。     

水中挥发性有机物分析的影响因素和常见问题解决办法

应用吹扫捕集-气相色谱-质谱法测定水中挥发性有机物,多种因素影响着定量分析的准确性,包括样品瓶的清洗及标准配制、样品和标准溶液的保存、载气气源的纯度、仪器状态检查及参数选择、分离度及积分方式。本文提出在分析过程中样品瓶必须清洗干净,以免污染样品;样品和标准溶液的保存时间过长会降低目标物的回收率;载气和吹扫气会带入杂质;分离度的大小将影响峰高和峰面积测量的准确度。针对分析中氯乙烯的回收、二氯甲烷的交叉污染、浑浊样品的处理等常见问题提供了解决方案,推荐采用选择扫描方式进行分析,并根据样品基体的情况来选择定量离子,将分析的初始温度降至40℃以下并保持2~3 min,以保证氯乙烯的回收率;实验室保持良好的通风环境,避免二氯甲烷交叉污染;色谱柱的最高温度升至220℃以上并保持2~3 min,可以排除萘及分子烷烃的干扰,保证分析的连续性;对于浑浊样品,推荐在野外取样时进行在线过滤或直接采用静态顶空方式进行测定。     

Origin of the Silurian Crude Oils and Reservoir Formation Characteristics in the Tazhong Uplift

<正>The Silurian stratum in the Tazhong uplift is an important horizon for exploration because it preserves some features of the hydrocarbons produced from multi-stage tectonic evolution.For this reason,the study of the origin of the Silurian oils and their formation characteristics constitutes a major part in revealing the mechanisms for the composite hydrocarbon accumulation zone in the Tazhong area.Geochemical investigations indicate that the physical properties of the Silurian oils in Tazhong vary with belts and blocks,i.e.,heavy oils are distributed in the TZ47-15 well-block in the North Slope while normal and light oils in the No.Ⅰfault belt and the TZ16 well-block,which means that the oil properties are controlled by structural patterns.Most biomarkers in the Silurian oils are similar to that of the Mid-Upper Ordovician source rocks,suggesting a good genetic relationship. However,the compound specific isotope of n-alkanes in the oils and the chemical components of the hydrocarbons in fluid inclusions indicate that these oils are mixed oils derived from both the Mid-Upper Ordovician and the Cambrian-Lower Ordovician source rocks.Most Silurian oils have a record of secondary alterations like earlier biodegradation,including the occurrence of "UCM" humps in the total ion current(TIC) chromatogram of saturated and aromatic hydrocarbons and 25-norhopane in saturated hydrocarbons of the crude oils,and regular changes in the abundances of light and heavy components from the structural low to the structural high.The fact that the Silurian oils are enriched in chain alkanes,e.g.,n-alkanes and 25-norhopane,suggests that they were mixed oils of the earlier degraded oils with the later normal oils.It is suggested that the Silurian oils experienced at least three episodes of petroleum charging according to the composition and distribution as well as the maturity of reservoir crude oils and the oils in fluid inclusions.The migration and accumulation models of these oils in the TZ47-15 well-blocks,the No.Ⅰfault belt and the TZ16 well-block are different from but related to each other.The investigation of the origin of the mixed oils and the hydrocarbon migration and accumulation mechanisms in different charging periods is of great significance to petroleum exploration in this area.