江浙沿海平原全新世浅层生物气气源岩地球化学特征研究

发布时间：2018-07-06 18:01

本文选题：浅层生物气 + 全新世　；参考：《南京大学》2017年硕士论文

【摘要】：全新世浅层生物气研究已经受到国内外诸多学者的重视,在湖相、河漫滩相、河口湾相、三角洲相以及浅海相等沉积环境中均有发现,其分布广、埋藏浅、易预测、成本低、见效快、前景好。江浙沿海平原地区全新世浅层生物气资源量丰富,以长江三角洲地区和杭州湾地区分布最为广泛。江浙沿海平原全新世浅层生物气研究精细程度不高,系统性差。本区全新统气源岩地球化学特征研究有利于进一步丰富生物气源岩评价指标和标准;为生物气的来源提供依据、丰富成藏理论和油气地球化学理论;此外,为发现新的气源岩、寻找有利富集带、计算生气量、部署勘探提供现实指导意义。本研究通过对江浙沿海平原中较为典型的长江三角洲启东地区和杭州湾萧山地区典型钻孔ZK01井、SE02井全新统气源岩的系统采样,对生物气气源岩的沉积特征、沉积环境、有机地球化学特征进行了较为系统的研究。以有机碳含量(TOC)、氯仿沥青"A"含量分别代表可溶有机质、不溶有机质丰度,二者共同表征有机质丰度。依据干酪根有机元素组成、干酪根镜检特征确定不溶有机质类型;依据氯仿沥青"A"族组成和饱和烃气相色谱特征确定可溶有机质类型。结合饱和烃气相色谱、岩石热解、镜质体反射率(Ro)相应参数特征,分析气源岩有机质成熟度。总结和探讨了江浙沿海平原晚第四纪浅层生物气地球化学特征及生气控制因素。研究认为长江三角洲启东地区全新统河口湾—河漫滩相灰色黏土及粉砂质黏土与浅海相深灰色淤泥质黏土为浅层生物气两套气源岩;杭州湾萧山地区全新统河口湾—河漫滩相灰及灰黄色黏土和粉砂质黏土与浅海相青灰色淤泥质黏土浅层生物气两套气源岩。江浙沿海平原气源岩处于较为理想的还原环境,有利于生气。江浙沿海平原河口湾—河漫滩相气源岩有机质丰度高于后者,生气能力略强;杭州湾地区同层位气源岩有机质丰度高于长江三角洲地区。全新统气源岩有机质来源由低等水生生物和陆源高等植物两部分组成,属于混源输入,且以陆源高等植物有机质为主,有机质类型为含草本腐殖型、含草本腐泥腐殖型。全新统气源岩中有机质尚处于未成熟阶段,浅层生物气主要为生物化学作用阶段的产物。江浙沿海平原晚第四纪浅层天然气为典型CO2还原生物化学作用形成的生物气。江浙沿海平原晚第四纪以来大幅度海平面升降、持续构造沉降、快速沉积、河口地区有利沉积环境为生物气的形成提供了必要的地质条件,其次,全新统气源岩具有良好的物质条件,再次,气源岩所处的还原环境、淡水—微咸水—咸水水介质、较低硫酸盐含量,适宜的酸碱度,利于产甲烷菌的生长。这些因素相互作用,相互补充,相互制约,有利于生物气的生成。
[Abstract]:The study of shallow biogas in Holocene has been paid much attention by many scholars at home and abroad. It has been found in lake facies, floodplain facies, estuarine bay facies, delta facies and the equivalent sedimentary environment of shallow sea. They are widely distributed, shallow buried, easy to predict and low in cost. The results are quick and the prospects are good. The shallow biogas resources of the Holocene in Jiangsu and Zhejiang coastal plain areas are abundant, and the Yangtze River Delta and Hangzhou Bay are the most widely distributed areas. The study of shallow biogas of Holocene in Jiangsu and Zhejiang coastal plains is of low precision and poor systematicness. The study of geochemical characteristics of new gas source rocks in this area is conducive to further enriching the evaluation indexes and standards of biogenic gas source rocks, providing the basis for the source of biogas, enriching the theory of reservoir formation and oil and gas geochemistry, in addition, for the discovery of new gas source rocks, Looking for favorable enrichment zones, calculating the amount of gas generated, and deploying exploration provide practical guidance significance. In this study, the sedimentary characteristics and sedimentary environment of biogas source rocks were studied through systematic sampling of the new gas source rocks in the typical borehole ZK01 well ZK01 well in Qidong area of Yangtze River Delta and in Xiaoshan region of Hangzhou Bay in Jiangsu and Zhejiang coastal plains, as well as the sedimentary environment of biogas source rocks. The organic geochemical characteristics have been systematically studied. Organic carbon content (TOC) and chloroform asphalt "A" content represent soluble organic matter and insoluble organic matter abundance respectively. The type of insoluble organic matter was determined according to the composition of organic elements in kerogen, the type of insoluble organic matter was determined by microscopic examination of kerogen, and the type of soluble organic matter was determined according to the composition of "A" group of chloroform asphalt and the gas chromatographic characteristics of saturated hydrocarbon. The maturity of organic matter in gas source rocks is analyzed by means of saturated hydrocarbon gas chromatography pyrolysis and vitrinite reflectance (Ro) parameters. Geochemical characteristics of shallow biogas in late Quaternary and controlling factors of gas generation in Jiangsu and Zhejiang coastal plains are summarized and discussed. It is considered that the grey clay and silty clay and dark gray silt clay in Qidong area of the Yangtze River Delta are two sets of shallow biogas gas source rocks. In Xiaoshan area of Hangzhou Bay two sets of gas source rocks such as greyish-yellow clay and silty clay and shallow marine greyish muddy clay shallow biogas are formed in the new Estuary and floodplain facies of Hangzhou Bay. The gas source rocks in Jiangsu and Zhejiang coastal plains are in an ideal environment for gas generation. The organic matter abundance of estuarine and floodplain gas source rocks in Jiangsu and Zhejiang coastal plains is higher than that of the latter, and the organic matter abundance of the same layer gas source rocks in Hangzhou Bay is higher than that in the Yangtze River Delta. The source of organic matter in the gas source rocks of the new series is composed of two parts: low aquatic organisms and higher terrestrial plants. It belongs to mixed source input and is mainly composed of terrestrial higher plant organic matter. The organic matter type is herbaceous humic type and herbaceous saprophytic mud humus type. The organic matter in the new gas source rocks is still in the immature stage, and the shallow biogas is mainly the product of biochemical process. The late Quaternary shallow natural gas in Jiangsu and Zhejiang coastal plains is a kind of biogas formed by the typical biochemical process of CO _ 2 reduction. Since the late Quaternary, the coastal plain of Jiangsu and Zhejiang has experienced large sea level rise and fall, sustained tectonic subsidence, rapid sedimentation and favorable sedimentary environment in estuarine areas, which provide the necessary geological conditions for the formation of biogas. The gas source rocks of the new series have good material conditions. Thirdly, the reduction environment of the gas source rocks, the medium of fresh water, brackish water and salt water, the lower sulfate content and the suitable acidity and alkalinity are beneficial to the growth of methanogenic bacteria. These factors interact, complement and restrict each other, which is beneficial to the formation of biogas.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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