风化校正作用在烃源岩有机地化研究中的应用

Application of Weathering Correction in Organic Geochemistry of Source Rocks

米伟伟 王腾 李娜 郭晓丹 谢小飞

MIWeiwei WANGTeng LINa GUOXiaodan XIEXiaofei

陕西延长石油集团研究院, 陕西 西安 710075 长安大学地球科学与资源学院, 陕西 西安 710061

Research Institute of Yanchang Petroleum(Group) Co. Ltd., Xi'an, Shaanxi 710075, China School of Earth and Resources Science, Chang'an University, Xi'an, Shaanxi 710061, China

通过对哈密拗陷下二叠统野外剖面观察和样品采集，运用岩石热解、有机碳测试、干酪根分析及饱和烃气相色谱等技术进行室内样品测试，在与前人分析数据相结合的基础上，利用风化校正作用对哈密拗陷下二叠统露头烃源岩有机质丰度、有机质类型进行评价，同时探讨了有机质成熟度、原始沉积环境和生源特征。结果表明，哈密拗陷下二叠统烃源岩属于好-很好的烃源岩，有机质类型以腐泥腐殖型（Ⅱ）为主，少部分腐殖型（Ⅲ）；有机质热演化程度高，处于高成熟阶段低-中期；烃源岩正构烷烃分布变化较大，呈前低后高的双峰特征，与很低的轻重烃比值相映，反映出有机质受陆源生物影响较大。低Pr/Ph比值显示出强烈的植烷优势，沉积环境具有较强的还原性，盐度较高，应属于半封闭水体。

Through field profile observation and sample collection of the Lower Permian in Hami Depression, the laboratory test was carried out by using rock pyrolysis, organic carbon test, kerogen analysis, gas chromatograms of saturated hydrocarbonand other technologies. On the basis of a combination with existing analysis data, this paper gives systematic evaluation about abundance of organic matter, type and maturity grade of Lower Permian Hami Depression source rocks, discusses the primary sedimentary environment and source characteristics of organic materials. Relevant results show that Lower Permian Hami Depression source rocks are very good source rock. The major type of organic materials give priority is sapropel humus type (Ⅱ), with a small amount of humus types (Ⅲ); the organic materials are the low-medium period of highly mature stage with high grande of evolution; n-alkanes of source rocks present great changes in distribution, a twin-peak feature of low first and high later. The contrast with quite low light-heavy hydrocarbon ratio reflects that organic materials are significantly influenced by terrigenous organisms. The low Pr/Ph ratio shows strong phytane advantages. Sedimentary environment presents relatively strong reducibility with high salinity, so it is semi-closed water.

10.11885/j.issn.1674-5086.2019.07.04.02