Pore-scale analysis of the effects of contact angle hysteresis on blob mobilisation in a pore doublet

The mobilisation of residual oil blobs in porous media is hampered by the so-called Jamin effect. We studied the Jamin effect experimentally in a pore doublet model and explain it through contact angle hysteresis. We measured the contact angles (in 2D and 3D) and the mean curvatures of a blob trapped in the pore doublet model. Due to gravity effects and hysteresis, the contact angles were initially (subject to zero pressure gradient) non-uniform and exhibited a pronounced altitude dependence. As the pressure gradient was increased, both the altitude dependence and non-uniformity of contact angles decreased, and the mean curvature of the drainage and imbibition interfaces increased and decreased, respectively. The predicted pressure drops inferred from our theory were in line with the directly measured ones. We also developed methods to measure contact angles and mean curvatures in 3D [Received: June 02, 2011; Accepted: September 07, 2011]