淮北杨柳矿区煤系构造热演化对页岩气生成与保存的影响  

Influence of tectono-thermal evolution on coal-bearing shale gas generation and preservation in the Yangliu mining area,Huaibei,China

作　　者：余坤 万志军[1] 琚宜文 王朱亭 赵帅 乔鹏 YU Kun;WAN Zhijun;JU Yiwen;WANG Zhuting;ZHAO Shuai;QIAO Peng(School of Mines,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国矿业大学矿业工程学院,江苏徐州221116 [2]中国科学院大学地球与行星科学学院,北京100049

出　　处：《地质学报》2023年第8期2690-2701,共12页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42202138);江苏省卓越博士后计划(编号2022ZB520);江苏省自然科学基金项目(编号BK20221145、BK20221133)联合资助的成果。

摘　　要：在“双碳”目标背景下,大力发展以页岩气为代表的低碳清洁能源是实现“碳减排”的重要途径。华北南部淮北地区蕴藏着丰富的煤系页岩气资源,但受复杂构造热演化影响,区域内页岩气生成与保存机理尚不清晰。因此,本文采用镜质组反射率、岩石热解、裂变径迹和盆地模拟技术研究了华北南部淮北地区晚古生代以来的构造热演化与生烃过程,讨论了复杂构造热作用下煤系页岩气的生成和保存机理。结果表明,淮北地区煤系页岩气生成过程受到燕山期构造热事件的显著控制,晚侏罗世基性岩浆侵入煤系使得下石盒子组和山西组页岩经历最高古温度达~172℃,对应热流峰值124 mW/m^(2)。煤系页岩Ro值在0.87%~1.74%,最高热解温度(Tmax)在437~563℃,表明有机质进入轻质油—湿气生成阶段。研究区二叠系山西组砂岩磷灰石裂变径迹年龄(60~42 Ma)明显小于所在地层年龄(298~272 Ma),部分锆石裂变径迹年龄略低于地层年龄,证实了研究区发生了强烈的岩浆热活动,导致地温梯度达到峰值~65℃/km。燕山期岩浆热效应促使区域煤系页岩高效生烃成藏,太平洋板块俯冲后撤引起的伸展断裂使得强构造变形区页岩气藏破坏逸散。因此,在淮北地区,弱构造变形区并伴有适度岩浆活动的区域具备页岩气保存的良好条件,具有良好的油气勘探前景。Under the goal of“carbon peak and carbon neutrality”,vigorously developing low-carbon and clean energy represented by shale gas is an important way to achieve carbon emission reduction.The Huaibei area in southern North China is rich in coal-bearing shale gas resources,but the mechanism of shale gas generation and preservation in this area is still unclear due to the influence of complex tectono-thermal evolution.Therefore,by using vitrinite reflectance,rock pyrolysis,fission track,and basin simulation techniques,this study analyzes the tectono-thermal evolution and hydrocarbon generation process of Huaibei area in southern North China since the Late Paleozoic and discusses the generation and preservation mechanism of coal-bearing shale gas under complex tectono-thermal activity.The results show that the generation process of coal-bearing shale gas in the Huaibei area is significantly controlled by the Yanshanian tectono-thermal events.The maximum paleotemperature of the Xiashihezi and the Shanxi shales reached~172℃,corresponding to the peak heat flow of 124 mW/m^(2),due to the intrusion of basic magma into coal measures in the Late Jurassic.The Ro values of coal-bearing shale range from 0.87%to 1.74%,and the maximum pyrolysis temperatures(Tmax)range from 437℃to 563℃,indicating that organic matter has entered the stage of light oil-wet gas stage.The fission track age of sandstone apatite(60~42 Ma)in the Permian Shanxi Formation is significantly lower than that of the strata(298~272 Ma)in the study area,and the fission track age of some zircons is slightly lower than that of the strata,which confirms that a strong magmatic thermal event occurred in this area,resulting in a peak geothermal gradient of~65℃/km.The magmatic thermal effect of the Yanshanian period promote efficient hydrocarbon generation and accumulation of regional coal-bearing shale,and the extensional faults caused by the roll-back subduction of the Pacific plate lead to the destruction and escape of shale gas reservoirs in the strong te

关 键 词：淮北地区 构造热事件 热流 地温场 煤系页岩气 

分 类 号：P618.13[天文地球—矿床学]