河北献县地热田地热异常的分布特征及成因机制  

Distribution characteristics and genetic mechanism of the geothermalabnormality in the Xianxian geothermal field,Hebei Province

作　　者：汪新伟[1] 高楠安 王婷灏 刘慧盈 毛小平[2] 黄旭 WANG Xinwei;GAO Nanan;WANG Tinghao;LIU Huiying;MAO Xiaoping;HUANG Xu(Sinopec Star Petroleum Co.Ltd.,Beijing 100083,China;China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国石化集团新星石油有限责任公司,北京100083 [2]中国地质大学(北京),北京100083

出　　处：《地质学报》2022年第7期2611-2625,共15页Acta Geologica Sinica

基　　金：中国石化集团重点科技项目“渤海湾盆地重点地区地热资源评价与开发技术政策”(编号JP19002)资助的成果。

摘　　要：沉积盆地内地热田地热异常成因机制的定量研究对认识盆地浅部不同构造带之间传热与聚热的差异以及指导盆地中低温地热资源的勘探有着重要的理论与现实意义。河北献县地热田在厚1300~1500 m新生界盖层覆盖下发育蓟县系雾迷山组(Jxw)基岩热储,已开发区的井口水温多高达90~95℃,是一个典型的中低温传导型地热资源区。本文基于横穿献县凸起及邻区的地震剖面,运用2D有限元数值模拟技术,定量—半定量地分析了献县凸起带及邻区热传导与热聚集的差异,并简述了对地热勘探的指导意义。模拟表明,献县凸起带盖层内的地热正异常是高热导率的基岩凸起段所引起的热量快速传递、并在盖层内逐渐累积的结果;献县地热田Jxw组热储顶部的地层温度比饶阳凹陷的同深度地层至少高~20℃,与其近3600 m的基岩凸起幅度密切相关。献县凸起带的地温场在纵向上具“非对称镜像”分布特征,且盖层段的平均地温梯度约为热储层段的3倍,表明浅部盖层段的地热正异常越“富集”,则深部基岩热储段的地热负异常越“亏空”。“高导均化深度”代表了基岩凸起段深部与其相邻凹陷区平均地温梯度相等的热传导平衡线位置。有效盖层覆盖下的基岩凸起带是地热勘探的有利区带,基岩热储在凸起段顶部之下的500~800 m深度段是浅部地热开发的甜段区,而位于“高导均化深度”之下的深部高温热储勘探需极力避开基岩凸起带,而优选盆地低凸起带或凹陷带的有利储集相带。The quantitative study of the genetic mechanism of geothermal anomalies in sedimentary basins has important theoretical and practical significance for understanding the difference between heat-conduction and heat-focusing in shallow basins and guiding the exploration of low-medium temperature geothermal resources.The Xianxian geothermal field,Hebei Province,as a typical low-medium temperature conduction geothermal resource area,developed as the carbonate-bedrock geothermal reservoir of the Wumishan Formation of the Jixian system(Jxw) under a Cenozoic cover of 1300~1600 m.The wellhead water temperature of most wells in the development zone is as high as 90~95℃.Here,based on the seismic profile across the Xianxian uplift and adjacent areas,we use 2 D finite element numerical modeling to quantitatively and semi-quantitatively investigate the difference between heat-conduction and heat-focusing in the Xianxian uplift and adjacent zones,then briefly describe the guiding significance for geothermal exploration.Our results show that the geothermal anomaly in the cover layer of the Xianxian uplift resulted from rapid heat transfer in the bedrock and progressive heat accumulation in the cover-rock caused by the high thermal-conductivity of the Jxw bedrock;and that the layer temperature at the top of the Jxw geothermal reservoir in the Xianxian uplift is at least ~20℃ higher than that at the same depth strata in the Raoyang sag,which is closely related to the bedrock uplift amplitude of nearly 3600 m.The temperature distribution in the Xianxian uplift has the characteristics of “an asymmetric mirror-reflection” structure in the longitudinal direction,and the average geothermal gradient of the caprock section is about three times that of the geothermal reservoir section.This indicates that the more “enriched” the positive geothermal anomaly in the shallow caprock section is,the more “deficit” the negative geothermal anomaly in the deep bedrock geothermal reservoir section is.The “homogenization depth of be

关 键 词：地热异常 数值模拟 非对称镜像结构 高导均化深度 献县地热田 

分 类 号：P314[天文地球—固体地球物理学]