Tied up

What is the meaning of tied up in this sentence/

"This viscous mechanism should be such that water is tied up and the mechanical and capillary forces of invasion are overcome.

thank you for your help.

What’s the wider context?

A primary role of the high yield stress shear thinning system is that of stopping invasion by creating a viscous resistance to flow. This viscous mechanism should be such that water is [color=red]tied up and the mechanical and capillary forces of invasion are overcome. In order to complete the invasion control and minimize penetration of the formation, many favor the creation of a filter cake using solids to bridge at the formation openings. This filter or wall cake is effective in controlling losses to permeable sands or small openings, and less effective in stopping losses to fractured or vugular zones.

It’s too technical, sorry.