摘要
将不同相态的二氧化碳(CO_(2))注入难以开采的煤层过程中,会引发复杂的物理与化学反应,由此导致的煤层储层渗流特性变化规律仍存在显著研究空白。为解决这一问题,本文以内蒙古敏东一矿矿区为研究对象,将敏东一矿的煤样放入自制的三轴吸附渗透仪中,通过调控温度和压力进行不同相态CO_(2)对煤样的吸附试验,以模拟复杂地应力条件下不同相态CO_(2)在赋存条件差的煤层中的吸附过程。首先通过测量吸附后煤样的渗透率和波速,得到渗透率与孔隙压力、有效应力间的关系,然后依据裂隙隔断效应,通过波速衰减率表征了CO_(2)对煤样的劣化程度。试验结果表明:1)煤样的渗透率演化受控于吸附CO_(2)相态差异引起的基质膨胀效应,以及有效应力变化导致的裂隙闭合行为的耦合作用。2)随着煤样吸附CO_(2)相态从气态经液态过渡到超临界态,渗透率因基质-裂隙耦合作用的增强而逐渐增大。3)煤样吸附CO_(2)时,内部裂隙扩大并连通,导致煤样的声波传播速度与CO_(2)注入压力呈负相关。4)随相态由气态至液态再至超临界态的转变,煤样的声波衰减率逐渐增大,使煤样内部渗流通道得到改善。
During the injection of carbon dioxide(CO_(2))in different phases into hard-to-reach coal seams,complex physical and chemical reactions occur,and the variation laws of the seepage characteristics of the coal seam reservoirs caused by this remain significant research gaps.To address these issues,this paper took the mining area of Mindong No.1 Mine in Inner Mongolia as the research object.Coal samples from Mindong No.1 Mine were placed in a self-made triaxial adsorption and permeability instrument.The adsorption experiments of different phases of CO_(2) on the coal samples were conducted by regulating temperature and pressure to simulate the adsorption process of different phases of CO_(2) in coal seams with poor storage conditions under complex in-situ stress conditions.Firstly,the relationship of permeability with pore pressure and effective stress was obtained by measuring the permeability and wave velocity of the coal samples after adsorption.Then,based on the fracture isolation effect,the deterioration degree of the coal body caused by CO_(2) was characterized by the wave velocity attenuation rate.The experimental results show that:1)The evolution of the permeability of the coal samples is controlled by the coupling effect of the matrix expansion effect caused by the phase difference of adsorbed CO_(2) and the fracture closure behavior caused by the change of effective stress.2)As the phase of CO_(2) adsorbed by the coal samples transitions from gaseous to liquid and then to supercritical,the permeability gradually increases due to the enhanced coupling effect of the matrix and fractures.3)When the coal body adsorbs CO_(2),internal fractures expand and connect,resulting in a negative correlation between the acoustic wave propagation velocity of the coal body and the injection pressure of CO_(2).4)As the phase changes from gaseous to liquid and then to supercritical,the acoustic wave attenuation rate of the coal body gradually increases,improving the internal seepage channels of the coal body.
作者
唐巨鹏
张枭
赖堂锐
余泓浩
TANG Jupeng;ZHANG Xiao;LAI Tangrui;YU Honghao(School of Mechanics and Engineering,Liaoning Technical University,Fuxin 123000,Liaoning,China;New Energy Research Center,Liaoning Technical University,Fuxin 123000,Liaoning,China)
出处
《实验力学》
北大核心
2025年第2期221-232,共12页
Journal of Experimental Mechanics
基金
国家自然科学基金面上项目(51874165)
辽宁省兴辽英才计划项目(XLYC1902106)
内蒙古科技重大专项(2021ZD0034-2)。
