Abstract: To study the conductivity changing rules of low-rank coal reservoir during methane absorption and desorption, this paper, based on a case study on No.4 coal seam in Binchang coal mine, measures the resistivity of different coal samples during methane absorption and desorption, studies the conductivity changing rules and mechanism, and compares their variance of different coal rocks. Conductivity rises during the absorption process with an ascending pressure. Relation among resistivity, absorption quantity and equilibrium pressure can be described as a quadratic function. During pressure-descending-desorption process, conductivity rises slightly; it has linear relation with absorption quantity and equilibrium pressure. Heat-releasing and coal matrix swelling make a rise in conductivity during methane absorption, and vice versa. Methane absorption results in an irreversible change in coal structure; its resistivity cannot be recovered to its original level even after methane desorption. Durain, with high ash, even pore throat structure and less charged particles, is weaker than vitrain in conductivity, but stronger in absorption, leading to a greater and faster decrease in conductivity during methane absorption.

Key words: low-rank coal, coal reservoir, resistivity, coal rock components, absorption and desorption 

摘要： 为了系统探究甲烷吸附解吸过程中低煤阶煤储层导电性变化规律，以彬长地区4#煤层为研究对象，通过测定不同煤岩组分样品甲烷吸附解吸过程中的电阻率，探究吸附和解吸过程中煤的导电性变化规律及机理，并对比分析不同煤岩组分导电性变化差异。研究认为，升压吸附过程中煤的导电性逐渐增强，电阻率与吸附量、平衡压力之间的关系可用一元二次函数描述；降压解吸过程中煤的电阻率小幅度回升，其与吸附量、平衡压力之间为线性关系；甲烷吸附过程中放热和煤基质膨胀变形，使得导电性增强，解吸过程中吸热和煤基质收缩，使得导电性变差；甲烷吸附会导致煤的结构发生不可逆转的变化，即使甲烷解吸后，煤的电阻率也难以恢复到初始水平；暗煤灰分高，孔喉结构相对均匀，双电层带电粒子更少，导电性较镜煤弱，加之暗煤吸附能力强，使得其在吸附过程中电阻率下降幅度和速率更大。 

关键词: 低煤阶；煤储层；电阻率；煤岩组分；吸附解吸