Nuclear magnetic resonance technology can be used to simulate the T2 spectrum distribution characteristics of different fracture parameters of fractured shale. Based on scanning electron microscope data of lacustrine shale strata, a petrophysical model of fractured shale is established, and the shapes of pores and fractures are simplified into spheres and ellipsoids, respectively. According to the aspect ratio of the ellipsoid and the log Gaussian function to control the crack shape. The simulation results show that the NMR response of fractured shale is unique, which is related to fracture shape, fracture width and fracture density. The fracture width has a greater influence on the T2 spectrum distribution of fractured shale. With the increase of the crack width, the T2 spectrum distribution shows a “double peak”-“single peak”-“double peak” trend. As the crack density increases, the T2 spectrum distribution changes from “single peak” to “double peak”. The shale model with needle-shaped fractures contributes the most to the connectivity of the pore-fracture model, and the shale model with pie-shaped fractures contributes the least to the connectivity of the pore-fracture model.

The nucleation mechanism of the hydrate is still not fully understood and is a challenge to the hydrate evaluation. We synthesized the low consolidated hydrate bearing sediments by the tetrahydrofuran (THF) and water, and monitored the nucleation process of THF hydrate using the two dimensional longitudinal relaxation-transversal relaxation (T1-T2) nuclear magnetic resonance (NMR) method. It is observed that the nucleation rate of the right peak is higher than the left peak at low THF hydrate concentration, while is opposite when the THF hydrate concentration is high, revealing that the hydrate forms preferentially in larger pores and then forms gradually in smaller pores. In addition, ratio of longitudinal relaxation time to transversal relaxation time (T1/T2) of the left peak is increased with the increase of hydrate concentration, while the right peak remains unchanged, indicating that hydrate saturation can be estimated by T1/T2.