Acoustic characterization for creep behaviors of marine sandy hydrate-bearing sediment

作者：Yanlong Li, Qiaobo Hu, Nengyou Wu, Hongbin Wang, Xiaofeng Sun, Gaowei Hu, Zhiwen Sun, Yujing Jiang · 发表于：Scientific Reports · 年份：2023 · DOI：10.1038/s41598-023-49523-1 · 被引用次数：36 · 研究领域：Methane Hydrates and Related Phenomena、Atmospheric and Environmental Gas Dynamics、Arctic and Antarctic ice dynamics

Marine natural gas hydrate (NGH) is a promising substitutive low-carbon energy resource, whereas NGH-production induced geoengineering concerns remain challenging. Advanced forecast of possible geoengineering risks is the fundamental for eco-friendly NGH exploitation. Reservoir creep deformation is an early symptom of the geoengineering risks. However, whether the creep deformation behaviors of the NGH-bearing strata is predictable remains controversial. In this study, a series of multi-step loading creep test are conducted for sandy gas hydrate bearing sediment (GHBS) samples, during which the ultrasonic responses are recorded simultaneously. The acoustic velocity, compression-to-shear velocity ratio, Poission's ratio, main frequency, and main frequency amplitude are used to characterize creep failures of the GHBS for the first time. Combining analyses of the creep behaviors and acoustic responses yield the following conclusions. Firstly, the long-term strength derived from creeping test is 0.45-0.60 times of the shear strength derived from triaxial shearing. Ignoring the creep effect might underestimate the scale and intensity of possible geoengineering risks during long-term NGH exploitation. Secondly, the acoustic velocity increases gently and then decreases continuously during creeping. Once the accelerated creep appears, the acoustic velocity plummets significantly, together with a sudden decrease in the compression-to-shear velocity ratio, and fluctuations in the main ...