Hazardous subsurface flow processes monitoring by Shear(S-) Waves for better control and mitigation

What is it about?

Such situations in engineering practices may arise where light oils, or other toxic fluids such as concentrated solutions as brines may be spilled or get infiltrated into the unconsolidated near surface sediments. They may pose both environmental and engineering problems. This is to say that the infiltrated sediments may become toxic where the infiltrate may spread by several transportation mechanisms too, to adverse effects. Also, there physical presence and an interaction could alter the surrounding sediment strengths over time. The infiltrates may become complex as they may tend to mix in several situations. One analogous process to evaluate for a broader understanding of such situations is immiscible displacement. Further a non destructive monitoring method offers better evaluation as it ensures that the probed sediments remain undisturbed and more realistic results may anticipated. Hence, S-wave method or survey application for monitoring and evaluating such situations is described.

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Why is it important?

An immiscible displacement process, in well planned experiments, was thus investigated in laboratory settings using such data ( ultrasonic and electrical) as acquired integrated, including presented S-wave results, too. Presented S-wave results were validated also by other methods and data which are not explained in this article. Explained S-wave results assume certain peculiarities. The results, spectrograms in essence, definitely help fix and discriminate macro morphologies of the porous immiscible flow as invading brine fraction, invaded oil fraction and an evolving interface. The significance of the method is that, somehow counter intuitively, S-wave spatio-temporal windows offer better resolution or more detail of flow-structure compared to similar methods as for example P-wave. In this regard the interface and its morphological strength aspect can also be inferred as a monolayer with some resolvable resilience property.

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