Abstract High performance water removal plays a significant role in restoring the gas production when water invasion happens to tight gas reservoirs. In this paper, core samples with the air permeability in range of 0.01–1 mD were selected to investigate water removal behavior in tight gas reservoirs. Meanwhile, the gas flow capability during the process of water removal was discussed. The water desaturation curves generally experienced two stages of water removal in a drainage process: a fast water decline stage induced by immiscible displacement, followed by a long period of slow water saturation reduction stage via the gas flow-through drying. It pointed out that the immiscible displacement mainly affects water removal during the drainage process in which period continuous gas flow channel was built. Once the generation of continuous gas flow channel was accomplished during the immiscible displacement stage, a proper increase of displacement pressure difference can efficiently enhance the gas flow-through drying rate. Normally, it was easy for high permeable tight core sample to experience a short immiscible displacement dominant stage and step into gas flow-through drying dominant stage afterwards. Besides, it was found that the enlargement in water invasion depth will weaken gas flow capacity from water removal. These findings help in understanding the physical process of water removal in tight gas reservoirs, as well as designing a better performance of water removal in a tight gas flied.

中文翻译：

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致密岩体排水过程中除水与气流的实验研究

摘要 致密气藏发生水侵时，高效除水对恢复产气具有重要作用。本文选取透气率在 0.01~1 mD 范围内的岩心样品，研究致密气藏的除水行为。同时，讨论了除水过程中的气体流动能力。水饱和度曲线在排水过程中通常经历两个除水阶段：由不混溶驱替引起的快速水下降阶段，然后是通过气流干燥的长时间缓慢水饱和度下降阶段。指出非混相驱替主要影响排水过程中的除水，该过程中建立了连续气流通道。一旦在非混相驱替阶段完成连续气流通道的生成，适当增加驱替压差可以有效提高气流干燥速率。通常情况下，高渗透致密岩心样品很容易经历短暂的不混溶驱替主导阶段，然后进入气流干燥主导阶段。此外，发现水侵深度的增加会削弱去除水的气体流动能力。这些发现有助于了解致密气藏中除水的物理过程，以及设计出更好的致密气除水性能。适当增大置换压差可以有效提高气流干燥速率。通常情况下，高渗透致密岩心样品很容易经历短暂的不混溶驱替主导阶段，然后进入气流干燥主导阶段。此外，发现水侵深度的增加会削弱除水的气体流动能力。这些发现有助于了解致密气藏中除水的物理过程，以及设计出更好的致密气除水性能。适当增大置换压差可以有效提高气流干燥速率。通常情况下，高渗透致密岩心样品很容易经历短暂的不混溶驱替主导阶段，然后进入气流干燥主导阶段。此外，发现水侵深度的增加会削弱除水的气体流动能力。这些发现有助于了解致密气藏中除水的物理过程，以及设计出更好的致密气除水性能。研究发现，水侵深度的增加会削弱除水的气体流动能力。这些发现有助于了解致密气藏中除水的物理过程，以及设计出更好的致密气除水性能。研究发现，水侵深度的增加会削弱除水的气体流动能力。这些发现有助于了解致密气藏中除水的物理过程，以及设计出更好的致密气除水性能。