天津典型观测井渗透性变化及对玛多7.4级地震响应机理分析  

Permeability Changes of Tianjin Typical Observation Wells and Coseismic Response Mechanism to Maduo M_(S)7.4 Earthquake

作　　者：李悦[1] 马晗宇 刘振辉 王熠熙[1] 邵永新[1] LI Yue;MA Han-yu;LIU Zhen-hui;WANG Yi-xi;SHAO Yong-xin(Tianjin Earthquake Agency,Tianjin 300201,China;Tianjin Geological Environment Monitoring Centre,Tianjin 300191,China)

机构地区：[1]天津市地震局,天津300201 [2]天津市地质环境监测总站,天津300191

出　　处：《地震》2024年第2期33-51,共19页Earthquake

基　　金：天津市地质环境监测项目(津地矿任[2024]1号);天津市地震局科研项目(2021210)。

摘　　要：采用微水试验和固体潮汐反演两种方法计算了王3井、宝坻新井、宁河井不同时期渗透系数,经对比分析发现,两种方法计算含水层渗透系数所得结果在总体量级上是相当的,并且变化趋势是一致的,发育稳定、连续性较好的含水层中的观测井,二者计算结果更加接近。微水试验估算的井含水层渗透系数主要反映了井孔周围局部含水层渗透能力在短时间内水流过程中的渗透性特征,而固体潮汐反演估算的渗透系数则反映了在较长时间内较大范围含水层的平均渗透能力。因而,在观测井同震响应分析、抽(注)水干扰等异常核实分析中,使用微水试验估算的井含水层渗透系数更为合理,而在分析区域应力场变化中使用固体潮汐反演估算的渗透系数则更合理。本文分析了三口观测井水位和渗透性变化特征以及产生原因,并进一步分析了王3井和宝坻新井水位对2021年5月22日青海玛多7.4级地震同震响应机理,以及玛多地震对宁河井水位观测的影响机制,发现应力积累、抽/注水干扰、地震波传播等因素均会对含水介质渗透性造成影响。并且,地震波传播过程对不同含水介质造成的影响不同,而含水层岩性相同的不同观测井对同一地震的响应特征和机理也不相同。This article uses two methods, slug test and tide inversion, to calculate the permeability coefficient of Wang 3 Well, Baodi New Well, and Ninghe Well at different periods. Comparing the calculation results, we find that the results obtained by using two methods are comparable in overall magnitude, and the trend of change is consistent. Especially for observation wells in aquifers with stable development and good continuity, the calculation results of the two methods are closer. The permeability coefficient estimated by slug test mainly reflects the permeability characteristics of the local aquifer around the wellbore during the short-term water flow process. The permeability coefficient estimated by tide inversion reflects the average permeability of a large range of aquifers over a long period of time. Therefore, in the analysis of coseismic response and abnormal verification of water pumping(injection) interference, using slug tests to estimate the permeability coefficient of the well aquifer is more reasonable, and it is more reasonable to use tide inversion to estimate the permeability coefficient in analyzing regional stress field changes.We analyze the characteristics and causes of water level and permeability change characteristics and causes of the three observation wells, as well as, we analyze mechanism of water level coseismic response in Wang 3 Well and Baodi New Well to the Maduo M_(S)7.4 earthquake in Qinghai Province on May 22, 2021, and the impact mechanism of the Maduo earthquake to water level in Ninghe Well. We find that factors, such as stress accumulation, pumping or injection water, and seismic wave propagation, can affect the permeability of aquifer medium. Moreover, the propagation process of seismic waves has different impacts on different aquifer medium, and the response characteristics and mechanisms of observation wells with the same aquifer lithology to the same earthquake are also different.

关 键 词：渗透系数 微水试验 固体潮汐反演 同震响应 2021年玛多7.4级地震 

分 类 号：P315.7[天文地球—地震学]