This week in the lab, Alex Shand has been working on a soy-based plugging agent. Plugging agents are just what they sound like: they are used to prevent leakage in places where leaks are not wanted (such as wells) by blocking off permeable membranes or zones that liquids can pass through. These agents are made mostly from gels, graded solids or fine vegetable material. One application for these biodegradable agents is sealing and plugging earthen boreholes in oil and gas wells. The soy-based substance forms a filter cake around the wall of the well, preventing the expensive drilling fluid from soaking into the surrounding rock.