本研究聚焦于CO2地质封存，鉴于其在实现“双碳”目标中的关键作用，以及监测其有效性和安全性的重要性，开展不同封存阶段CO2的地震数值模拟意义重大。文中先阐述了选题背景、国内外研究现状，点明当前研究面临的难题。随后，基于多孔介质渗流理论，运用Julia语言对CO2地质封存过程进行数值模拟，分析了不同阶段CO2的运移规律。接着，依据Biot双相介质动力学理论，采用有限差分法和PML边界条件进行双相介质地震数值模拟实验，研究了不同地质封存时期地震波的传播特性。结果表明，在不同封存阶段，地震波的传播特征存在显著差异，如慢纵波在遇到CO2注入点后会产生绕射波，且随着CO2运移范围扩大，透射慢纵波的波形变化加剧。同时，分析了渗透率和CO2饱和度对相速度及逆品质因子的影响，发现低渗含高CO2饱和度层在地震频带内具有较强的衰减和频散特征。本研究为CO2地质封存运移时移地震检测提供参考。
关键词
CO?地质封存；双相介质；地震数值模拟；Biot理论
Abstract
ThisstudyfocusesonCO?geologicalsequestration.Givenitscrucialroleinachievingthedual-carbongoalsandtheimportanceofmonitoringitseffectivenessandsafety,conductingseismicnumericalsimulationsofCO?atdifferentsequestrationstagesisofgreatsignificance.Thispaperfirstexpoundsontheresearchbackgroundandtheresearchstatusathomeandabroad,pointingoutthechallengesfacedbycurrentresearch.Subsequently,basedontheporousmediaseepagetheory,JulialanguageisusedtonumericallysimulatetheCO?geologicalsequestrationprocess,andthemigrationlawsofCO?atdifferentstagesareanalyzed.Then,basedonBiotstwo-phasemediumdynamicstheory,thefinitedifferencemethodandPMLboundaryconditionsareadoptedtoconductseismicnumericalsimulationexperimentsoftwo-phasemedia,andthepropagationcharacteristicsofseismicwavesindifferentgeologicalsequestrationperiodsarestudied.Theresultsshowthattherearesignificantdifferencesinthepropagationcharacteristicsofseismicwavesatdifferentsequestrationstages.Forexample,theslowP-wavegeneratesdiffractedwaveswhenitencounterstheCO?injectionpoint,andasthemigrationrangeofCO?expands,thewaveformofthetransmittedslowP-wavechangesmoreseverely.Atthesametime,theinfluencesofpermeabilityandCO?saturationonthephasevelocityandinversequalityfactorareanalyzed.Itisfoundthatthelow-permeabilitylayerwithhighCO?saturationhasstrongattenuationanddispersioncharacteristicswit