四川盆地西部致密砂岩气来源及运移地球化学示踪

通过典型钻井天然气组分、轻烃、碳同位素以及烃源岩抽提轻烃的系统测试,研究了四川盆地西部致密砂岩气的成因类型和来源。研究表明,研究区致密砂岩气以煤型气为主,须二段（T₃x²）存在部分混合气。天然气来源具有下生上储的特征,其中须二段（T₃x²）天然气主要来源于须二段（T₃x²）自身的烃源岩以及下伏小塘子-马鞍塘组（T₃m+t）烃源岩,须四段（T₃x⁴）天然气主要来源于须三段（T₃x³）烃源岩,天然气运移距离短;而侏罗系天然气则主要来源于下伏须五段（T₃x⁵）烃源岩以及须家河组早期气藏的贡献,天然气运移距离长。在此基础上,优选了3组9类天然气运移地球化学指标,分别为：①天然气运移方向和距离指标为甲烷含量［W（CH₄）］、乙烷含量［W（C₂H₆）］、非烃含量［W（CO₂）］,［W（N₂）］、甲烷碳同位素（δ¹³C₁）;②天然气运移相态指标为苯/正己烷、苯/环己烷;③天然气运移通道指标为iC₄/nC₄和iC₅/nC₅。对研究区陆相天然气的运移进行了示踪,明确了研究区致密砂岩气的运移方向、运移相态以及运移通道。结果表明：研究区上侏罗统天然气主要由下部须家河组天然气沿高速优势通道窜层渗流运移而来,断裂是其最重要的运移通道;中侏罗统部分天然气由须家河组气源沿高速运移通道运移而来,而部分天然气为下部气源以水溶相的方式运移聚集成藏;须四段（T₃x⁴）天然气成藏时,储层相对致密,运移通道发育不佳,天然气以扩散相短距离运移为主;须二段（T₃x²）天然气主要通过断裂及其伴生裂缝以游离相和水溶相短距离运移为主。     

四川盆地中侏罗统沙溪庙组天然气地球化学特征及成因

四川盆地中侏罗统沙溪庙组是低油价形势下四川盆地天然气勘探的重要领域,但盆地内不同地区天然气来源尚不明确,影响下一步勘探部署决策,为此开展侏罗系沙溪庙组天然气地球化学特征及成因研究。结果表明：①沙溪庙组天然气属于干酪根降解气,甲烷含量>84%,含少量乙烷、丙烷等烃类气体及少量的氮气、二氧化碳等非烃气体,不含硫化氢,不同区域的天然气成熟度存在差别;②天然气δ¹³C₁值为-39.2‰~-31.2‰、δ¹³C₂值为-32.8‰~-22.3‰、δ¹³C₃值为 -28.7‰~-19.5‰,天然气碳同位素未发生倒转,川西地区为煤成气,川中地区为油型气,川东地区为煤成气和油型气混合气,以油型气为主;③不同区域天然气δ¹³C₁值、δ¹³C₂值的差异,与其来源于不同类型烃源岩贡献比例大小有关。川西、川西南地区主力烃源岩为须五段煤系烃源岩,川中地区为下侏罗统湖相烃源岩,川东地区天然气来源于须五段和下侏罗统烃源岩。研究结果对四川盆地侏罗系沙溪庙组下一步天然气勘探部署决策具有重要的指导意义。     

东濮凹陷CO2气源岩及地球化学特征

东濮凹陷在下古生界奥陶系风化壳与下第三系Es¹₃地层发现了高含CO₂气层(显示)。通过气源对比分析证实,该凹陷文留构造文33块、文269块Es¹₃中的有机气体是来源于下第三系碎屑岩地层生成的油型气,其CO₂则是石炭系-二叠系的煤在二次生烃中伴生的CO₂与下古生界奥陶系灰岩高温分解生成的无机CO₂混合而成。对东濮凹陷这2类CO₂气源岩进行高温模拟实验发现,石炭系-二叠系的煤生气能力是奥陶系灰岩的9倍,煤生成的气体70％~80%为甲烷,少量为CO₂;而灰岩所生气中95%以上为CO₂气;单位质量的煤与灰岩生成的气体中CO2体积相当,煤是东濮凹陷最重要的气源岩。     

Hydrogeological and geochemical studies of the Efteni and Derdin geothermal areas,Turkey

The Efteni and Derdin geothermal areas are located in northwestern Turkey. Relatively low-temperature springs emerge from the Duzce Fault, a normal-component-dominated fault segment of the North Anatolian Fault System. The thermal waters of the Efteni and Derdin Springs show distinct geochemical and isotopic characteristics since they originate from different geothermal reservoirs and reflect the effects of different water–rock interaction processes. Geothermometry revealed higher reservoir temperatures for the Efteni system, however a strong δ¹⁸O shift, interpreted as being the result of isotopic exchange at high temperatures, was observed in the Derdin system. Hydrogeological and geochemical techniques are applied to identify recharge mechanisms, water–rock interaction processes and to construct conceptual models of these geothermal systems.     

叠合盆地油气运聚期次研究方法及应用

我国多为陆相叠合盆地,具有多期生排烃、运移、成藏、调整和破坏的特点。归纳有关油气运移方面的文献,将油气运聚期次的研究方法归纳为４种：即以分析构造运动后地层表现形式的构造分析法、以研究流体包裹体为主要内容的储集层有机岩石学分析法、储集层成岩矿物（主要是伊利石）同位素地质年代法和用于推断储集层中烃类流体充注史、烃类注入方向和时间的油藏地球化学－油藏非均质性研究法。４种方法分别具不同的分析原理和应用效果,并在吐哈盆地分别进行了应用。构造分析法和储集层有机岩石学分析法得出葡北油田主要经历了侏罗纪末─早白垩世和晚第三纪两期油气大规模运移;葡北油田同位素地质定年分析只反映出油气第二期运移成藏时期,其原因是第一期油气没有充满取样层位所造成;油藏地球化学－油藏非均质性分析得出鲁克沁构造油藏是油气先稠化后成藏的结论。     

Geochemistry of the upper Han River basin, China: 2: Seasonal variations in major ion compositions and contribution of precipitation chemistry to the dissolved load

A total of 252 water samples were collected from 42 sites across the upper Han River basin during the time period from 2005–2006. Major ions (Cl⁻, NO₃⁻, SO₄²⁻, HCO₃⁻, Na⁺, K⁺, Ca²⁺ and Mg²⁺), Si, water temperature, pH, EC and TDS were determined and consequently correlation matrix, analysis of variance, factor analysis and principal component analysis were performed in order to identify their seasonal variations and atmospheric inputs into river solutes. The results reveal that pH, EC, TDS, Cl⁻, SO₄²⁻, HCO₃⁻, Ca²⁺ and Mg²⁺, K⁺ and Si generally tend to show the minimum compositions in months belong to the rainy season, while the dry season for NO₃⁻ and Na⁺. NO₃⁻, Mg²⁺ and Si have the maximum concentrations in months belong to the rainy season. By comparing the major ions relating to hydrological regime, NO₃⁻, contrary to other elements, has higher concentration in the rainy season. The overall water quality is non-polluted, while there are indications of enrichment of inorganic anions including NO₃⁻ causing water entrophication in the near future. The atmospheric inputs contribute to river solutes is limited with a mean inputs of approximate 1% in the basin. The understanding of the major ion dynamics would help water quality conservation in the basin for China's interbasin water transfer project.     

东濮凹陷桥口深层气地球化学特征及勘探潜力

深层天然气勘探在桥口东翼取得重大突破,该地区油气呈上油下气倒置的特征,Es2-Es3^1地层为油,天然气一般富集于3600m Es3^3以下的地层。通过天然气成分、碳同位素、Ar^40/Ar^36等地化指标分析认为,其气源主要为油型气,也有部分煤型气输入。桥24井油气注入史分析认为,该地区油气有2期注入,第一期以油为主,第二期以气为主,第二期油气注入形成了桥口深层天然气藏。桥口东民办深层天然气的勘探前梨园洼陷一侧比葛岗集洼陷一侧更为有利。     

Riparian zone influence on stream water chemistry at different spatial scales: a GIS-based modelling approach, an example for the Dee, NE Scotland

A geographical information system (GIS-ARC/INFO) was used to collate existing spatial data sets on catchment characteristics to predict stream water quality using simple empirical models. The study, based on the river Dee catchment in NE Scotland, found that geological maps and associated geochemical information provided a suitable framework for predicting chemical parameters associated with acidification sensitivity (including alkalinity and base cation concentrations). In particular, it was found that in relatively undisturbed catchments, the parent material and geochemistry of the riparian zone, when combined with a simple hydrological flow path model, could be used to accurately predict stream water chemistry at a range of flows (Q95 to > Q5) and spatial scales (1-1000 km2). This probably reflects the importance of the riparian zone as an area where hydrological inputs to stream systems occur via flow paths in the soil and groundwater zones. Thus, evolution of drainage water chemistry appears to retain the geochemical characteristics of the riparian area as it enters the channel network. In more intensively managed catchments, riparian land use is a further influential factor, which can be incorporated into models to improve predictions for certain base cations. The utility in providing simple hydrochemical models, based on readily available data sets, to assist environmental managers in planning land use in catchment systems is discussed.     

一种基于GIS的地球化学数据处理新方法及应用

快速准确有效的数据处理方法是日益增长的地学数据为成矿预测工作提出的迫切要求。提出了一种基于GIS的地球化学数据处理新方法,克服了传统统计分析方法对样本数据要求服从正态或对数正态分布,处理结果受少数特高品位数据影响的缺点。通过凤凰山铜矿地球化学数据处理的对比分析,认为该方法具有较好的抗干扰和致矿异常分辨能力。     

松辽盆地滨北地区生物气源岩酸性含氧化合物的分布及其地球化学意义

松辽盆地滨北地区白垩系源岩有机质演化程度低(Ro值为0.33%～0.70%),可溶有机质酸性非烃主要由正构一元酸、正构二元酸、姥鲛烷酸、植烷酸、藿烷酸和甾烷酸等化合物组成。其中正构一元酸含量占绝对优势并呈两种分布形态(一为单峰型,以C16为主峰,C18、C14丰度较高,生源母质主要为藻类等水生生物;二为双峰型,前峰群以C16为主峰,后峰群为次主峰,以C24为主,前峰群表征水生生物输入,后峰群表征有陆源高等植物输入),各形态均呈现偶奇优势(与生物脂肪酸合成酶合成双碳乙酰单元有关);正构二元酸含量较低;藿烷酸含量高于甾烷酸。随着埋藏深度的增加,多数样品的姥鲛烷酸/植烷酸的比值及甾烷酸/藿烷酸的比值均减小,表明沉积环境逐渐向还原环境转化。认为由于酸性含氧化合物尤其是正构烷基脂肪酸的脱羧反应,故在形成正构烷烃的同时形成CO2,不仅为产甲烷菌提供了大量营养能源,而且也提供了呼吸代谢的基质;在青山口组和嫩江组时期,湖盆面积扩大,水体加深,区域内出现滨浅湖―半深湖相沉积,因此滨北地区局部时空范围内可形成商业性生物气田。