Laboratory Simulation of Vertical Hydrocarbon Microseepage

Based on a conceptual model of hydrocarbon microseepage, a macro-sized experimental equipment used the matched mixtures of cement and quartz sand as simulated caprock and its overlying strata is first set up to simulate the processes of hydrocarbon microseepage and its near-surface expressions. The results of the simulation experiments suggest that simulated caprock and its overlying strata have a certain sealed capability; hydrocarbon microseepage is dominated by the pressure of point gas source, and temperature plays only a subordinate role; on the path of hydrocarbon microseepage, the distribution of hydrocarbon concentration is fan-shaped; differential adsorption of alkanes by the simulated caprock and its overlying strata results in the occurrence of a chromatographic effect. Different migrating patterns within simulated caprock are shown by the ratio of i-butane to n-butane. The concentration of hydrocarbon in the surface soil has good correspondence with the pressure of point gas source. These simulation results are significant to further study of the mechanism of anomalies recovered in surface geochemistry exploration.     

壤中游离气方法及其在油气化探中的应用

油气藏中的轻烃气体能够以微弱但可检出的量近似垂直地渗漏到地表土壤中,其中一部分烃类以游离态赋存在土壤或岩石颗粒空隙中.壤中游离气中的烃类能反映深部油气藏烃类的现代补偿性活跃微渗漏,被认为是油气地球化学勘探的最可靠方法之一.壤中游离气采集是获得第四系沉积层中微渗漏烃类地球化学异常的关键技术.自行研制了便携式游离气采集新装...     

井中油气化探异常模式及现场快速评价系统

井中化探有效地解决了近地表化探较难回答的生、储、盖及烃类垂向微渗逸等问题。使油气化探工作从近地表研究油气渗逸“痕迹”和晕圈异常进而预测目的层在平面上的位置转向直接对目的层进行研究和预测。为了适应现场快速及时预报及进一步完善井中化探方法系列，设计和编制了与井中化探方法系列相应的评价软件系统，通过在塔北某井现场检验，效果良好     

Magnetic, Geochemical and Mineralogical Charac teristics of Soils in Qiangtang Basin, Tibet, China: Implications for Prospective Oil and Gas Land

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Integrated geo-microbial and trace metal anomalies for detection of hydrocarbon microseepage in Ahmedabad block of Cambay basin,India

The aim of the present work is to define the geo-microbial signatures along with trace metals, and to investigate whether the geo-microbial anomalies have correlation with trace metal anomalies in Ahmedabad block of Cambay basin. The surface geochemical techniques are based on seepage of light hydrocarbon gases from the oil and gas pools to the shallow surface and can bring up near-surface oxidation reduction zones that favor the development of a diverse array of chemical and mineralogical changes. The paper reports the role of hydrocarbon microseepage in surface alterations of trace metal concentrations and hydrocarbon oxidizing bacteria and its interrelationship. For the purpose a total of 90 soil samples are collected in grid pattern of 2 x 2 km interval. The paper reports the chemical alterations associated with trace metals in soils that are related to hydrocarbon microseepages above some of the major oil and gas fields of this petroliferous region. The concentrations of V (0 to149 ppm), Cr (2 to 192 ppm), Cu (4 to 171 ppm), Se (98 to 440 ppm), Zn (56 to 1215 ppm) are obtained. It is observed that the concentrations of trace elements are tremendously increased when they are compared with their normal concentrations in soils. In this study the hydrocarbon oxidizing bacterial counts ranged between 1.0 x 10³ and 1.59 x 10⁶ cfu/g of soil sample respectively. The attempt has made for the first time, which revealed good correlation as both these anomalies are found as apical in relation. Integrated studies between trace elements and hydrocarbon oxidizing bacterial anomalies showed positive correlation with existing oil and gas wells in the study area.     

油气化探技术在川西坳陷油气勘探中的应用

自“七五”以来,为配合四川盆地的油气勘探,在川西坳陷开展了一系列油气化探工作,对该区油气的发现起到了重要作用。川西坳陷的地质条件有利于微渗漏烃类以较高浓度赋存于土壤中,从而有利于油气地球化学探测方法的使用。选择有代表性的大型气田——新场气田进行近地表地球化学场特征与石油地质关系解剖,结果表明气田上方近地表地球化学异常是客观存在的,与本区独特的地质环境相对应,并优选出勘探天然气的有效指标组合。这些有效的油气化探方法在川西天然气富集区的预测中同样效果显著,以川西新都-金堂地区油气化探详查为例,许多化探异常经钻探后证实具有工业油气流。上述研究表明,油气化探技术在川西坳陷具有良好的应用前景。     

微生物勘探技术在潮汕坳陷油气勘探中的应用初探

东沙海域潮汕坳陷中生界研究程度相对较低,油气分布规律不明,为了加强对该区油气分布和富集规律的研究,针对潮汕坳陷西部地质目标首次应用微生物地球化学勘探技术(MGCE),探讨其含油气性。MGCE技术以轻烃微渗漏理论为基础,采用地质微生物学方法和地球化学方法检测研究区海底表层的微生物异常和吸附烃异常,预测研究区下伏地层中油气的富集区及其油气性质。检测结果显示研究区西部凹陷的斜坡区微生物异常呈块状发育,轻烃微渗漏强度变化大,可能为潜在油气富集区,酸解吸附烃成果显示可能的油气性质为干气和凝析油气。     

烃类垂向微渗漏及其地表异常显示

烃类以微泡、水动力、扩散和渗透方式向地表迁移过程中,其效能、方式与油气藏的盖层、断裂与裂隙系统、储层的流体性质、地层压力等地质因素密切相关.通过对塔里木盆地雅克拉凝析气田上的地表、井中化探资料与地质资料的综合分析,认为该气田的井中垂向地球化学特征、控制烃类垂向微渗漏地质因素、地表化探异常显示之间呈现出很好的内在联系.     

中国油气化探的近期进展和发展方向

近10多年来,中国油气化探理念发生了重要转变,并取得了重大进展。开展了油气化探异常类型及成因机理研究,进行了烃类垂向微渗漏模拟试验,提出了“气相压驱裂隙渗透”理论;在酸解烃、蚀变碳酸盐、荧光、紫外等传统方法的基础上,开发了热释烃、高效液相色谱芳烃、物理吸附气、微生物专性烃菌等新方法;进行了非常规油气资源,尤其是天然气水合物、无机成因气的油气化探应用研究;开展了复杂地表区如沙漠、戈壁、黄土塬、山区等化探技术方法的研究;进行了雪样地球化学方法试验;海上化探蓬勃发展,尤其在南海、东海、黄海、渤海和台湾海峡开展了大量油气化探工作;研发了新的数据处理和解释评价技术,如决策分析、分形几何、人工神经网络等得到应用,建立了中国主要含油气盆地油气化探数据库。在总结经验的基础上,对油气化探的发展方向提出了一些见解。     

烃类垂向微渗漏理论研究现状及发展趋势

烃类垂向微渗漏理论是油气化探的基础理论,研究一直处于薄弱环节,影响了油气化探的深入研究和广泛应用.因此加强烃类垂向微渗漏理论研究是油气化探发展的重要方向.笔者以油气微渗漏作用的概念为切入点,论述了烃类垂向微渗漏过程的复杂性.从烃类垂向微渗漏基本理论研究方法方面,综述了研究现状和主要进展,提出了目前存在的问题,展望了烃类垂向微渗漏理论研究的发展趋势.     

Application of trace metal anomalies for recognition of petroleum prospects in surface sediments of Kutch and Saurashtra Basins, India

Seepage of hydrocarbons, either as macroseepage or microseepage, can set up near-surface oxidation-reduction zones that favour the development of a diverse array of chemical and mineralogic changes. In this study trace metal alterations were mapped that appear to be associated with hydrocarbon microseepages in the oil/gas fields. A total of 210 soil samples were collected from near surface sediments of Kutch and Saurashtra Basins, India. The soil samples were collected from a depth of 2–2.5 m. The paper reports the chemical alterations associated with trace metals in soils that are related to hydrocarbon microseepages above the Kutch and Saurashtra Basins, India. The soil samples for trace metals; Scandium (Sc), Vanadium (V), Chromium (Cr), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Barium (Ba) and Strontium (Sr) were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The concentrations of the trace elements ranged between for Sc (12.69 to 21.91 ppm), V (109.20 to 436.05 ppm), Cr (87.15 to 481.57 ppm), Co (18.25 to 64.31 ppm), Ni (57.55 to 263.15 ppm), Cu (44.88 to 143.96 ppm), Zn (137.60 to 502.31 ppm), Ba (149.27 to 921.46 ppm) and Sr (143.93 to 425.63 ppm) were obtained. It was observed that trace elements concentrations were tremendously increased when compared with normal concentration in the soils. The adsorbed soil gas analysis showed the presence of high concentrations of ΣC₂₊ (C₂H₆, C₃H₈ and n-C₄H₁₀) ranged between 1 to 121 ppb respectively. Integrated studies of trace elements over adsorbed light gaseous hydrocarbon (ΣC₂₊) anomalies showed good correlation. The carbon isotopic composition of δ¹³C₁ of the samples ranges between — 36.6 ‰ to ?22.7‰ (Pee Dee Belemnite) suggest thermogenic source for hydrocarbon gases. The increase in trace metal concentrations near oil/gas producing areas, suggests that soil chemical change to a reducing environment, presumably due to the influence of hydrocarbon microseepage, which could be applied with other geo-scientific data to identify areas of future hydrocarbon exploration in the frontier areas.     

含油气盆地油气同位素地球化学研究概述

以气体地球化学国家重点实验室工作为主，简要概述了对我国含油气的同位素地球化学研究。1．烃气的同位素地球化学：讨论了天然气成因新模式与气藏烃气同位素组成的关系，低演化阶段天然气同位素分馏的二阶段模式，云南中小盆地天然气低演化系列同位素特征及用储层解析气作油气源对比。2．稀有气体同位素地球化学：阐述了^3He/^4He值与中国构造分区，幔源氮的复合成藏和幔源甲烷问题以及气源对比等。3．液态烃同位素地球化学：简述了轻烃碳氢同位素特征及氢同位素作为判别古沉积介质盐度的指标，概述了未熟一低熟油同位素特征及在自然剖面上油和源油抽提物碳同位素分馏特征及其机理。     

利用近地表化探资料研究油气藏的保存条件及埋藏深度

利用地面化探资料能够有效地圈定出化探异常,指出烃类垂向运移发生的范围。但对于油、气勘探的需要,这仅仅是最基本的,是远远不够的。本文通过对垂向化探资料及地面游离烃化探资料的分析,对利用地化动力学指标判断油、气藏的保存条件及埋藏深度进行了初步的探讨。     

含油气盆地油气同位素地球化学研究概述①

以气体地球化学国家重点实验室工作为主,简要概述了对我国含油气的同位素地球化学研究。1. 烃气的同位素地球化学:讨论了天然气成因新模式与气藏烃气同位素组成的关系,低演化阶段天然气同位素分馏的二阶段模式,云南中小盆地天然气低演化系列同位素特征及用储层解析气作油气源对比。2. 稀有气体同位素地球化学:阐述了3He/4He值与中国构造分区, 幔源氦的复合成藏和幔源甲烷问题以及气源对比等。3. 液态烃同位素地球化学:简述了轻烃碳氢同位素特征及氢同位素作为判别古沉积介质盐度的指标,概述了未熟-低熟油同位素特征及在自然剖面上油和源岩抽提物碳同位素分馏特征及其机理。     

油气优势运移通道的类型及其物理模拟实验研究

地质分析和物理模拟实验证实地质条件下油气总是沿着浮力最大和阻力最小的的方向和通道运移,形成油气优势运移通道有5种基本模式:级差优势、分隔优势、流向优势、流压优势和断面优势。物理模拟实验结果表明油气运移实际通道只占输导层的1%~10%,但却运输了油气的绝大部分;输导层物性的差异、盖层沉降中心的偏移、流体动力、断层倾角及断层面几何形态控制了油气运移的优势通道;实际地质条件下油气运移所形成的优势通道是上述5种模式综合作用的结果。由于优势通道是大部分油气运移的实际路径,其研究对追踪油气来源、预测有利圈闭有着十分重要的作用。     

油气资源遥感勘查新方法

地下深处的油气藏中的烃类物质,在压力梯度下会向地表产生微渗漏,导致地表物质产生一系列理化异常,在地表形成吸附烃异常、红层退色、粘土化、碳酸盐化、放射性异常和地植物异常等标志。根据这些地表标志的地物波谱特征,选择出油气资源遥感勘查的最佳工作波段,在此基础上,以机载遥感信息为主,以星载遥感信息为辅,以地表地球化学、地植物学、地面遥感勘查作为验证手段,最终施行多元信息复合分析,可达到寻找油气藏的目的。     

浅谈吸附烃找油气方法中的干扰因素

吸附烃是油气化探的主要指标之一，它直接反映从油气藏运移出来的烃类气体。应用吸附烃法找地下油气藏应排除地层、地形、地貌景观的干扰异常。不同地层上方土壤中吸附烃含量变化可能与地层沉积时间、沉积环境有关；不同地形、地貌景观下土壤中吸附烃含量异则是由于地化环境（ｐＨ值等）所致。消除这些干扰因素的最简单方法是分区统计背景值，或者用不同异常下限或用衬度值圈定异常。经校正后的异常能更真实可靠地反映油气藏，已在四     

钻井现场有机地球化学录井与油气识别评价技术

在现场钻进过程中，尤其是在油基泥浆及各种添加剂烃类污染、地质录井难以确定真假油气显示的情况下，有机地球化学录井对确定油气显示有独特的作用。但由于其烃类污染对岩屑罐顶气、岩石冷溶烃、岩石热解等常规地球化学录井技术有不同程度的影响，其检测数据通过校正污染后才能用于含油气性评价。为此，在现场开展了钻井泥浆及各种添加剂中烃类有机地化检测试验，对泥浆中轻烃（C1－C12）、萃取烃（C1－C35）和岩石冷溶烃进行动态检测，研究其烃类组成及变化特征，对钻进中真假油气显示、油气层质量及产能大小、油气烃类母质类型、储油层确定等及时作出解释与评价，为油气勘探与开发快速提供地球化学依据。     

新疆伊犁盆地巩留凹陷航空高光谱油气探测

为了进一步了解伊犁盆地巩留凹陷油气勘探潜力,为该地区下一步油气勘查提供依据和新的技术支持,利用航空高光谱SASI数据,采用混合调制匹配滤波(MTMF)方法,在伊犁盆地阿吾拉勒西段山前提取了油气烃信息,主要分布在二叠系晓山萨依组,反映了油页岩层的分布和油气渗漏地段,地表油气渗漏主要受断裂控制,与油气渗漏有关的蚀变主要为粘土化,碳酸盐化次之。在巩留凹陷提取了粘土化和碳酸盐化信息,主要分布在拜石墩与阿克吐别克乡之间,通过干扰因素的排除,在拜石墩南部筛选了四片油气微渗漏区。最后,结合区域地质、物探资料综合分析,认为该地区油气成藏和排烃可能始于燕山早期,在喜山期遭到严重破坏,盆地的不对称压陷,加速了油气的垂直和侧向运移,在盆地内部形成微渗漏,在阿吾拉勒山前沿着断裂逸散至地表形成宏渗漏,巩留凹陷拜石墩南部微渗漏地区对应深部二叠系褶皱带是下一步油气勘查有利目标区。     

A Method for Eliminating Caprock Thickness Influence on Anomaly Intensities in Geochemical Surface Survey for Hydrocarbons

All petroliferous basins exhibit near-surface anomalous signals. The successful use of these signals must lead to great development in petroleum exploration. However, oil/gas fields cannot be effectively predicted in the case of intensive influence of caprock thickness on intensities of anomalies in a geochemical survey for hydrocarbons. In this paper, we first study the features of the influence of caprock thickness and then establish digital conceptual models for the influence in one and two dimensions. Finally, we develop techniques for eliminating this influence with wavelet analysis, based on the digital conceptual models. The newly developed techniques are applied to the actual data of acid-extractable hydrocarbons of soils in the southern slope of the Dongying Depression, East China where the anomaly intensities are considerably influenced by caprock thickness. The results illustrate that this new approach enables us to satisfactorily eliminate the influence of caprock thickness on anomaly intensities and thus can greatly improve the predictive capability of the existing geochemical data.