As a complex two-phase flow in naturally fractured coal formations, the prediction and analysis of CBM production remain challenging. This study presents a discrete fracture approach to modeling coalbed methane (CBM) and water flow in fractured coal reservoirs, particularly the influence of fracture orientation, fracture density, gravity, and fracture skeleton on fluid transport. The discrete fracture model is first verified by two water-flooding cases with multi- and single-fracture configurations. The verified model is then used to simulate CBM production from a discrete fractured reservoir using four different fracture patterns. The results indicate that fluid behavior is significantly affected by orientation, density, and fracture connectivity. Finally, several cases are performed to investigate the influence of gravity and fracture skeleton. The simulation results show that gas migrates upwards to the top reservoir during fluid extraction owing to buoyancy and the connected fracture skeleton plays a dominant role in fluid transport and methane production efficiency. Overall, the developed discrete fracture model provides a powerful tool to study two-phase flow in fractured coal reservoirs.

中文翻译：

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一种用于分析压裂煤层中煤层气和水流的离散裂缝建模方法

作为自然裂缝煤层中复杂的两相流，煤层气生产的预测和分析仍然具有挑战性。本研究提出了一种离散裂缝方法来模拟裂缝煤储层中的煤层气 (CBM) 和水流，特别是裂缝方向、裂缝密度、重力和裂缝骨架对流体输送的影响。离散裂缝模型首先通过具有多裂缝和单裂缝配置的两个注水案例进行验证。然后使用经过验证的模型来模拟使用四种不同裂缝模式的离散裂缝油藏的 CBM 生产。结果表明，流体行为受方向、密度和裂缝连通性的显着影响。最后，通过几个案例来研究重力和断裂骨架的影响。模拟结果表明，在流体开采过程中，由于浮力作用，气体向上运移至顶部储层，连通的裂缝骨架对流体输送和甲烷生产效率起主导作用。总体而言，开发的离散裂缝模型为研究裂缝煤储层中的两相流提供了强大的工具。