水-岩作用对富有机质页岩损伤敏感性机理研究

Study on the Sensitivity Mechanism of Water-Rock Interaction to the Damage of Organic-rich Shale

富有机质页岩水化是在黏土矿物发生表面水化、离子水化与渗透水化的基础上,水对岩石微观破坏逐步演化成宏观破坏造成岩石局部连续性丧失的过程,是水-岩相互接触时发生的一系列物理化学作用与力学作用的共同结果。因各种黏土矿物水化时产生的应力不均,将出现局部应力集中现象,导致页岩中原有裂缝扩展,无序裂纹增多,而出现的宏观裂纹又为工作液的持续进入提供通道,水分子可通过该通道加速与页岩内部黏土颗粒接触,颗粒间的胶结作用将被削弱,宏观表现为岩石内聚力和内摩擦角降低,抗压强度等下降。无机盐溶液质量浓度越高,抑制性越好。蒙脱石的层间距随着浸泡时间的增加而增大,而对温度和压力的敏感性较小。

Organic-rich shale hydration is based on the surface hydration,ion hydration,and osmotic hydration of clay minerals.The microscopic damage of water to the rock gradually evolves into a process of macroscopic damage resulting in the loss of local continuity of the rock.It is the result of a series of physical and chemical interactions and mechanical interactions that occur when water and rock are in contact with each other.Due to the uneven stress generated during the hydration of various clay minerals,local stress concentration will occur,leading to the expansion of the original cracks in the shale and the increase of disordered cracks.The macro cracks provide channels for the continuous entry of working fluid.Molecules can accelerate contact with the clay particles inside the shale through this channel,and the cementation between the particles will be weakened.The macroscopic performance is that the cohesion and internal friction angle of the rock are reduced,and the compressive strength is reduced.The higher the mass concentration of the inorganic salt solution,the better the inhibition.The interlayer spacing of montmorillonite increases with the increase of immersion time,but it is less sensitive to temperature and pressure.