Abstract
Salt crystallization will affect the mechanical strength of shale. In the present work, experiments on salt crystallization of shale were carried out, and static and dynamic rock mechanics of shale were analyzed. Meanwhile, the crystallization stress of nanopores and throats with different shapes was calculated. Crystallization stress will induce the initiation and expansion of shale fractures, which will further reduce the mechanical strength of shale. When the pore radius of shale is less than 50 nm, the crystallization stress decreases rapidly. When the pore radius is constant, the larger the throat radius, the smaller the crystallization stress, and the crystallization stress generated when the throat radius is 5 nm is much larger than that generated when the throat radius is greater than 10 nm. Salt crystallization will weaken the mechanical strength of shale, increase the embedding degree of proppant, reduce the effective crack width, and finally hinder the multi-scale transportation of shale gas.
NSTL