摘要
流体运移时携带热量,会产生温度变化.温度作为地下流体的示踪剂得到了广泛应用,但通常需要事先确定热扩散系数.实际上,基于浅层地壳不同深度的周期性温度-时间序列,利用流体运动对振幅和相位的影响,可以同步获取热扩散系数和地下流体运移信息.本文以新疆喀什地区5个钻孔不同深度的基岩温度数据为基础,获取了热扩散系数和流体运移特征.主要成果有:(1)获得了不同测点的热扩散系数α,以及视热扩散系αA和αΦ(即单独通过振幅或相位获得的热扩散系数).其中,α、αA和αΦ的值分别为1.52~8.91、0.79~1.71和(1.53~33.1)×10^(-6) m 2·s^(-1).另外,当流体热效应不明显时,通过相位获得的视热扩散系αΦ更接近真实的热扩散系数α.(2)获得了不同测点的流体流向和流速信息.测点的流体流向均向上,靠近天山地区的测点流体流速为(0.10~1.94)×10^(-7) m·s^(-1),靠近昆仑山地区的测点流体流速为(8.56~9.71)×10^(-7) m·s^(-1),不同地区测点流体流速的差异可能与区域水文地质环境有关.总之,通过多深度的连续基岩温度观测,有望获得浅层地壳的热扩散系数及流体运移特征.
When fluid flows,it carries heat,which causes temperature changes.Temperature has been widely used as a tracer of underground fluid,however,it is usually necessary to determine the thermal diffusivity in advance.In fact,based on the periodic temperature-time series of different depths in the shallow crust,the effects of fluid flow on amplitude and phase can be used to simultaneously estimate thermal diffusivity and migration information of underground fluid.Based on observation data of bedrock temperature at different depths of 5 boreholes in Kashi,Xinjiang,thermal diffusivity and migration characteristics of fluid are simultaneously estimated in this paper.And the main results obtained are as follows:(1)Thermal diffusivityα,and the apparent thermal diffusivityαA andαΦ(that is,the thermal diffusivity deduced by the amplitude and phase alone)of different measurement stations are obtained.The values ofα,αA andαΦare 1.52~8.91,0.79~1.71 and(1.53~33.1)×10^(-6) m 2·s^(-1).In addition,when the thermal effect generated by fluid migration is not obvious,the apparent thermal diffusivity obtained from the phase is closer to the true thermal diffusivity.(2)We estimate velocity and direction of underground fluid flow at different measurement stations.The flow direction of fluid in the measurement station area is all upward,the fluid velocity of the measurement stations near Tianshan area ranges from 0.10×10^(-7) to 1.94×10^(-7) m·s^(-1),and the fluid velocity of the measurement stations near Kunlun Mountain area various from 8.56×10^(-7) to 9.71×10^(-7) m·s^(-1).The difference among the estimated fluid velocities at different measurement stations in different regions may be related to the hydrogeological environment.In sum,it is expected that the thermal diffusivity and fluid migration characteristics of the shallow crust can be estimated simultaneously from continuous bedrock temperature observations at multiple depths.
作者
卢丽莉
陈顺云
刘琼颖
闫玮
刘培洵
宋春燕
冯嘉辉
陈立春
LU LiLi;CHEN ShunYun;LIU QiongYing;YAN Wei;LIU PeiXun;SONG ChunYan;FENG JiaHui;CHEN LiChun(Xinjiang Pamir Intracontinental Subduction National Field Scientific Observation and Research Station,Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Earthquake Administration of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Guilin University of Technology,Guilin 541006,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第12期4594-4606,共13页
Chinese Journal of Geophysics
基金
国家重点研发计划(2018YFC1503304)
中央级公益性科研院所基本科研业务专项(IGCEA1815,IGCEA1910)
国家自然科学基金面上项目(41474162)共同资助.
