煤层气储层渗透率动态变化规律研究综述

摘要

Permeability is a key parameter for coalbed methane (CBM) development.During the process of gas production, the effective stress of coal bed increases as the gas is released from the reservoir, which results in the decrease of permeability, and the physical property of the coal bed becomes more complex because of its particular way of draining.Now the variation law of coal properties during the process of production is still a difficulty, and its understanding has an important impact on the numerical simulation results verification and the success of draining technology and development plan.The dynamic variation rule of coalbed methane production and permeability was summarized based on the research result of foreign scholars and the existing models for coalbed permeability were analyzed in this paper.The results showed that the dynamic variation of permeability was influenced by many factors, which added to its complexity.The current prediction models for coalbed permeability variation put emphasis on different aspects and each had its own features and limitations.The model for characterization of coalbed permeability dynamic variation should be established with detailed parameters according to the actual situation of the coalbed reservoir.%煤储层渗透率是影响煤层气产量的关键性参数.在实际的煤层气开采过程中发现,随着气体的产出、煤层有效应力的增加,储层煤岩的渗透率下降,但是由于煤岩体本身及排采方式的独特性,其储层物性变化复杂.关于开采过程中煤储层物性的变化规律目前仍是一个难点问题,对其规律认识是否清楚将直接决定数值模拟是否合理可靠、排采制度是否合理乃至一次开发方案的成与败.通过对国外学者煤层气储量渗透率动态变化规律的研究进行总结,以及对前人建立的相关模型进行剖析,了解到煤储层渗透率动态变化规律复杂,受多种因素影响;前人所建模型从不同方面对煤储层物性变化进行了预测,各具特点,也存在一定的不足;建立描述煤层气储层渗透率动态变化的模型必须根据国内煤储层特征的实际情况,细化各种参数研究.