Microstructure test on tetrahydrofuran hydrates with microscale sands

For the production of natural gas hydrates with the depressurization method, safety problems may be caused by the existence of hydrates and microscale sands in the flow channels. Thus, it is particularly important to study the influence of microscale sands on the hydrates. For this reason, the hydrate formation and decomposition experiments in the presence of microscale sands were performed with tetrahydrofuran (THF) as an alternative medium. In this way, the morphological structure of hydrates was observed and the effect of microscale sands was analyzed. The results show that the microscale sands coexisting with THF hydrates are present in three forms, i.e., free state, adhesive state, and wrapped state. The presence of microscale sands will affect the agglomeration of hydrates, and the microscale sands entrapped in the hydrate layer during deposition will change the structure and mechanical properties of the hydrate layer. What's more, the microscale sands will accelerate the decomposition of hydrates, change the shedding way of hydrate deposit layer in the pipeline, and further affect the flow safety in the pipelines. Generally, the research results could provide reference for the analysis on deposition characteristics of the hydrates within the flow channels and the flow safety assessment thereof.