Pore-Scale Spontaneous Imbibition at High Advancing Contact Angles in Mixed-Wet Media: Theory and Experiment

Mixed wettability develops naturally on a pore scale in oil reservoirs after primary drainage. The invading fills interiors that become oil-wet by asphaltene deposition, while the residual water retreats into corners, masking them and retaining their wetness. This alteration hinders mobilization during secondary waterflood. Therefore, proper understanding of conditions controlling pore-scale imbibition mixed-wet pores may lead to substantial increase recovery from portions reservoir rocks bypassed original We use selective silane coating fabricate reservoir-representative capillaries with angular cross-sections. validate our procedure silica glass substrates characterize surfaces atomic force microscopy, scanning electron contact angle measurements. Subsequently, we investigate experimentally invasion against air mixed-wet, water-wet, square compare findings theoretical predictions dynamic (Washburn, Szekely, Bosanquet) quasi-static [Mayer–Stowe–Princen (MSP)] meniscus-invasion models. None models for ducts uniform can fully describe experimental data capillaries. However, results agree MSP theory. discuss similarities differences between experiment theory reasons failure To knowledge, this is first direct validation under such controlled manner. confirm possibility spontaneous piston-type high (>90°) advancing angles pores, given lowered below critical value function geometry saturation. In reservoirs, injection custom-designed brines would be required change values threshold.