Abstract Coalbed methane (CBM) is a form of natural gas that is extracted from coalbeds. Characterization of CBMs is very challenging mostly due to the very complex fracture system leading to ambiguous fluid and petrophysical properties. Among several important factors that control the performance of CBMs, permeability is the most crucial one, which summarizes the global fracture system, intensity, connectivity, and production ratio. As such, accurate characterization of CBMs is coupled with fracture delineation and permeability description, which resulted in the development of a wide range of methods. In this paper, all the necessary steps from imaging, segmentation, and modeling of the fractures to various methods of permeability evaluation are reviewed. This paper presents a critical review of all of the existing relevant and significant techniques and compares their performances with special reference to permeability prediction. Several practical and simplified computational methods for calculating permeability are thus reviewed and compared. Finally, this review paper summarizes the current challenges and possible future research.

中文翻译：

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数字煤层气实验和数值模拟综述：成像、分割、裂缝建模和渗透率预测

摘要 煤层气（CBM）是一种从煤层中提取的天然气。煤层气的表征非常具有挑战性，主要是由于非常复杂的裂缝系统导致不明确的流体和岩石物理特性。在控制煤层气性能的几个重要因素中，渗透率是最关键的一个，它概括了全球裂缝系统、强度、连通性和生产比。因此，煤层气的准确表征与裂缝描绘和渗透率描述相结合，导致了广泛的方法的发展。在本文中，回顾了从裂缝成像、分割和建模到各种渗透率评估方法的所有必要步骤。本文对所有现有的相关和重要技术进行了批判性审查，并特别参考了渗透率预测来比较它们的性能。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 因此，回顾和比较了几种用于计算渗透率的实用且简化的计算方法。最后，这篇综述论文总结了当前的挑战和未来可能的研究。