Thermal-insulation and temperature-resistant foamed gel for thermal management of heavy oil steam flooding

Abstract

Foamed clayey hydrogel Bent-5/PAM-2, with hierarchically double-network structure and abundant CO 2 air chambers inside, maintains low thermal conductivity and good plugging performance at high temperature, effectively reducing heat loss of heavy oil thermal recovery. • Clayey foamed hydrogel, with hierarchically double networks, was synthesized by one-pot method. • Foamed gel shows low thermal conductivity, high strength and good mobility at 300 °C. • Thermal effectiveness of steam flooding is obviously improved after foamed gel injection. Due to the serious gravity overriding and large heat loss, thermally insulated and temperature-resistant plugging agents are highly desired in steam flooding. In this work, a physically-crosslinked clayey foamed hydrogel Bent/PAM, with low thermal conductance, high thermal stability and good mobility, was synthesized by one-pot process, using bentonite as matrix and polyacrylamide as cross-linking agent. Bent/PAM has hierarchically 3D porous structure and double network. Specifically, abundant meso-sized air chambers in gel endows it with low thermal conductivity. And, its outer clay percolated network with micro-sized meshes provides a temperature-resistant coating, while the inner polymer-clay composite network with nano-sized meshes affords a high strength. On the other hand, the easily slidable clay platelets make its outer percolated network turn into a lubricating film, offering the foamed gel with low friction and viscosity. From the core flooding experiments, the Bent-5/PAM-2 gel (the optimal sample) possesses large plugging rate, plugging intensity and oil recovery (EOR), up to 83.7%, 321 KPa and 63.5%, respectively.