柴达木盆地第四纪更新世气候变化及其对有机质富集的影响  

Quaternary Pleistocene climate change in the Qaidam Basin and itseffect on organic matter enrichment

作　　者：刘晓雪 姜振学[1,2] 唐相路[1,2] 徐明帅 邵泽宇 朱军 LIU Xiaoxue;JIANG Zhenxue;TANG Xianglu;XU Mingshuai;SHAO Zeyu;ZHU Jun(Unconventional Petroleum Research Institute,China University of Petroleum-Beijing,Beijing 102249,China;State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum-Beijing,Beijing 102249,China;Research Institute of Exploration and Development,Qinghai Oilfield Company,PetroChina,Jiuquan 736202,China)

机构地区：[1]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [2]中国石油大学(北京)油气资源与工程全国重点实验室,北京102249 [3]中国石油青海油田分公司勘探开发研究院,酒泉736202

出　　处：《石油科学通报》2024年第3期394-407,共14页Petroleum Science Bulletin

基　　金：国家自然科学基金面上项目“陆相页岩储层岩石组构和孔隙结构特征及其对含气性的控制机理”(41872135)资助。

摘　　要：有机质是泥页岩生气的基础,研究柴达木盆地第四纪更新世气候变化及其对有机质富集的影响对于柴达木盆地生物成因气的勘探开发至关重要。本文选取柴达木盆地第四系更新统泥页岩为研究对象,通过主微量元素分析和饱和烃色谱分析等实验手段,从古湿度和古温度两个方面阐明了第四纪更新世气候变化特征,进而从生物生产力和有机质保存条件两个方面分析了气候变化对有机质富集的影响,建立了柴达木盆地第四纪更新世有机质沉积模式。结果表明:(1)第四纪更新世早—中期,气候温凉湿润,草本植物茂盛,草本植物富含纤维素、半纤维素、糖、淀粉和果胶,提高了水体表层的生物生产力;降水量大,水体分层性好,较强的水体分层还可使水体下层的还原性增强,有利于从上层沉积下来的有机物的保存,从而有利于沉积有机物的富集;且温度相对较低,抑制了产甲烷菌的活动,有利于有机质的保存;(2)更新世晚期,在新构造运动下,青藏高原隆升,气候变得干旱,气温上升,木本植物比例增大,产甲烷菌可利用的营养物质减少,生物生产力下降;水体分层性减弱,上层富氧水体和下层贫氧水体混合,导致下层水体还原性被破坏,从上层沉降下来的沉积有机物被破坏,不利于沉积有机物的保存;且温度相对较高,产甲烷菌消耗了大量的有机质,不利于有机质的保存。研究成果对研究区生物成因气的勘探开发具有理论和实践意义。Organic matter is the basis of shale gas generation,and the study of Quaternary Pleistocene climate change in the Qaidam Basin and its effect on organic matter enrichment is crucial for the exploration and development of biogenic gas in the Qaidam Basin.In this paper,the Quaternary shale in the Qaidam Basin is taken as the research object,and Quaternary Pleistocene climate change is clarified in terms of paleo-moisture and paleo-temperature through organic carbon analysis and main and trace element experiments.Then,the influence of climate change on organic matter enrichment is analyzed from two perspectives:biological productivity and organic matter preservation.Finally,the Quaternary Pleistocene organic matter depositional pattern of the Qaidam Basin is established.The results show that(1)in the early-middle Quaternary Pleistocene,the climate was cool and humid,the herbaceous plants were luxuriant,and rich in cellulose,hemicellulose,sugar,starch and pectin,which improved the biological productivity of the surface layer of the water column.The amount of precipitation was high,and the stratification of the water column was good.The strong stratification of the water column also enhanced the reduction level of the lower layer of the water column,which is favorable for the preservation of the organic matter deposited from the upper layer and thus favors the enrichment of sedimentary organic matter.Additionally,relatively low temperatures inhibit the activities of methanogenic bacteria,which is also conducive to the preservation of organic matter.(2)In the late Pleistocene,under the Neotectonic Movement,the Tibetan Plateau uplifted,the climate became arid,and the temperature increased,leading to an increase in the proportion of woody plants and a decrease in the amount of nutrients available to methanogenic bacteria,decreasing the biological productivity of the surface layer of the water column.On the other hand,the stratification of the water column was weakened.The mixing of oxygen-rich water in the upper layer an

关 键 词：第四纪更新世 泥页岩 生物成因气 生物生产力 保存条件 

分 类 号：P618.13[天文地球—矿床学] TE122[天文地球—地质学]