基于CDOM光谱特征的泥页岩产气特征评价  

Evaluation of the characteristics of biogenic gas production based on the CDOM spectral characteristics of shales

作　　者：郑晓璇 田继先[2] 田聪 蒋峥文 杨磊 贺秋芳 薛红蕾 ZHENG Xiaoxuan;TIAN Jixian;TIAN Cong;JIANG Zhengwen;YANG Lei;HE Qiufang;XUE Honglei(Chongqing Key Laboratory of Karst Environment,School of Geographic Sciences,Southwest University,Chongqing 400715,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;Research Institute of Exploration and Development,Qinghai Oilfield Company,PetroChina,Dunhuang Gansu 736202,China;Yantai Penglai District Agricultural Technology Promotion Center,Yantai Shandong 265600,China)

机构地区：[1]西南大学地理科学学院/岩溶环境重庆市重点实验室,重庆400715 [2]中国石油勘探开发研究院,北京100083 [3]中国石油青海油田公司勘探开发研究院,甘肃敦煌736202 [4]烟台市蓬莱区农业技术推广中心,山东烟台265600

出　　处：《地质科技通报》2024年第4期128-140,共13页Bulletin of Geological Science and Technology

基　　金：中国石油天然气股份有限公司前瞻性与基础性重大科技项目“不同类型大气田(区)成藏主控因素及邻域评价”(2021DJ0605)。

摘　　要：泥页岩中可溶有机质(DOM)组成和可降解性是影响生物气形成的重要因素,开发简便有效的方法来评估可溶有机质的组成、官能团特征和微生物活性等,可为泥页岩生物气田产气机制分析提供关键的基础信息。采集了柴达木盆地涩探1井1219~1309 m泥质岩心,基于有色可溶有机质(CDOM)的三维荧光(EEM)和紫外可见吸收光谱特征,分析了可溶有机质的组分、官能团特征和易降解程度,了解了产甲烷菌可利用底物的分布情况。结果表明:涩探1井岩心有机质以易降解的类色氨酸荧光组分C1和C3为主,占比70.54%;荧光组分、荧光参数HIX、BIX和吸光系数E_(253)/E_(203)、SUVA_(254)共同指示1219~1222 m和1285~1301 m2个层位有机质腐殖化程度较低,芳香性较弱,为潜在的产气活跃层位。研究表明CDOM光谱可以作为分析泥页岩可溶有机质特征的有效方法,其结果反映了产甲烷菌可利用底物和微生物活性等特征,为烃源层系内生物产气预测提供有效的重要信息。[Objective]The composition and degradability of dissolved organic matter(DOM)play a critical role in evaluating biogenic gas production during shale gas exploration.A simple and effective method needs to be developed to assess the composition,functional groups and microbial activity of DOM,which will provide crucial valuable information concerning the gas production mechanism in the field of biogenic shale gas.[Methods]Shale samples were collected from depths of 1219 m to 1309 m from the ST1 exploration well located at the edge of the Sebei No.1 gas field in the Qaidam Basin.According to the 3D fluorescence of the extraction and emission matrix(EEM)and the UV visible absorption spectrum characteristics of chromophoric dissolved organic matter(CDOM),the composition,functional group and degradation characteristics of CDOM were analysed to determine the distribution of methanol formation substrates.[Results]The DOM in the samples mainly consisted of the small molecular tryptophan-like fluorescent components C1 and C3,which are readily degradable by biotic processes and account for 70.54%of the total fluorescence intensity.The fluorescence components,fluorescence parameters(HIX,BIX),and absorbance ratios(E_(253)/E_(203),SUVA_(254))confirmed that the core layers at depths of 1219-1222 m and 1285-1301 m were potential effective gas-generating formations.These layers contain low amounts of humified organic matter,weak aromaticity and high amounts of methanol functional groups.The active gas-generating formations are generally consistent with those in previous reports.[Conclusion]The results indicated that the CDOM spectrum is a valuable method for exploring the methanol formation substrate distribution and microbial activity.The CDOM-EEM method has the potential to serve as an effective indicator of the methanol formation characteristics of DOM in mud shale and provides an effective and essential way to assess geochemical-based gas production capacity in hydrocarbon source rocks.

关 键 词：生物气 可溶有机质(DOM) CDOM三维荧光光谱 紫外-可见吸收光谱 柴达木盆地 泥页岩 

分 类 号：P618.13[天文地球—矿床学]