Shear induced structure additives and nonlinear pressure drop effects in permeable flow.

In classical flow through permeable rock, the pressure drop is linearly distributed through the medium. Shear induced structure materials, surfactant/co-solute pairs, were added to retard flow in higher permeability rock samples. A novel core holder allows the axial pressure distribution along the flow direction to be measured. This enables the pressure drop to be measured as a function of distance along the core. The results show the spatial scale and the effect on pressure distribution associated with varying concentrations of shear induced structure additives. Subsequent flushing with water leads to restoration of the original flow level. The rate of recovery is dependent on the pressure of flushing which determines shear--showing that break up of the shear induced structure materials deposited in the porous rock is also dependent on shear.