溶蚀作用对破碎泥岩渗透特性的影响

为研究溶蚀作用对破碎岩石渗透特性的影响,研制一种可测量质量流失条件下破碎岩石渗透特性的试验系统.在破碎泥岩的渗透试验中掺入岩盐模拟自然条件下存在的溶蚀现象,加速溶蚀过程.讨论溶蚀作用下破碎泥岩渗透特性的演化规律,分析溶蚀作用下渗透压力、岩盐质量和泥岩颗粒粒径对破碎泥岩渗透特性的影响.结果表明:溶蚀作用导致破碎岩石内易溶物质和细小颗粒的流失极易破坏岩样内部的孔隙结构和骨架结构,由此造成结构内部导水通道的扩大和渗透参数的突增.其渗透参数基本与渗透压力、岩盐质量和泥岩颗粒粒径呈正相关关系.且对于渗透压力较大、岩盐质量较高和泥岩颗粒粒径较大的岩样,由于溶蚀作用的存在容易发生更明显的导水通道扩大现象.此外,在岩样的渗流过程中,也存在由于颗粒迁移导致的导水通道堵塞造成的渗透参数逐渐减小的现象.
In order to study the effect of dissolution on the seepage property of broken rock, an experimental system for testing the seepage property of broken rock under the condition of mass loss was designed. The halite was added in the broken mudstone to simulate the dissolution phenomena in nature, which can accelerate the dissolution process. The evolution law of seepage property of broken mudstone under dissolution was discussed. The effects of seepage pressure, halite content, and particle size of mudstone on the permeability of broken mudstone under dissolution were analyzed. The results show that dissolution caused loss of soluble matters and fine particles in broken rock to damage the pore structure and framework structure inside that specimen easily, thereby resulting in the expansion of underground watercourse in structure and the sharp increase of permeability parameters. The permeability parameters were positively related to the seepage pressure, halite content, and particle size of mudstone. For the rock specimen with greater seepage pressure, higher halite content, and larger particle size of mudstone, the more obvious expansion of underground watercourse tended to occur due to dissolution. In addition, in the seepage process of rock specimens, the watercourse blockage caused by the particles migrations also occurred, which results in the gradual decrease of permeability parameters.