页岩储层流动机制综述

A Review of Flow Mechanisms in Shale Gas Reservoir

为了研究页岩储层的流动机制,对国内外页岩气流动机理相关文献进行了广泛调研,详细阐述了解吸附、扩散和渗流的数学描述方法、影响因素、适用条件及存在的问题,为流动机制的深入研究提供参考。分析表明:气体在页岩储层中的流动主要经历解吸附、扩散和渗流3个过程。Langmuir等温吸附定律很好地描述了页岩气的解吸附规律,但在描述多组分气体解吸附时仍存在一定问题,需要进一步研究;Fick第二扩散定律能够准确地描述页岩气的扩散过程,如何划分渗流和扩散的流动区间并进行耦合还需进一步研究;气体在天然裂缝网络中的流动遵循滑脱效应的广义达西定律,在压裂诱导裂缝中的流动遵循Forchheimer定律;天然气在页岩储层的流动存在压敏、气水两相流动、温度变化引起的热效应、相变等多种流动机制,需要进一步研究。

This paper reviews the studies both at home and abroad of the gas flow mechanisms in shale gas reservoirs. The mathematical description methods, the influencing factors, the applicability and the disadvantages of the desorption, the diffusion and the seepage are analyzed. It is shown that the gas flow in the shale reservoir includes desorption, diffusion and seepage. The Langmuir isothermal adsorption law could describe the shale gas desorption accurately, but further researches are needed for the law to describe muhi- component gas desorption. The Fick second diffusion law describes the gas diffusion in the matrix effectively, but the coupling between the diffusion and the seepage needs to be further studied. The gas seepage in the natural fractures follows the generalized Darcy＇s law with consideration of the slippage effect, and the gas seepage in the artificial fractures follows the Forchheimer equation. The pressure- sensitive effect, the two-phase flow of gas and water, the thermal effects, and the phase transition are the additional flow mechanisms in the shale gas reservoir that need to be further studied.