Unlocking the enormous potential of biological materials: Polymer-assisted foam for enhanced oil recovery in fractured porous media

Abstract

In natural fractured reservoirs, foam serves as an effective method for mobility control, leading to a significant enhancement in oil recovery. However, the harsh conditions of reservoirs present challenges to the strength and stability of foams. In this study, we conducted comprehensive experimental research, employing a combination and screening approach, to successfully develop a super foam using biomacromolecules (Welan gum) and bio-based surfactants (APG). Bulk foam tests were carried out and the performance of foam flooding in fractured porous media was evaluated. The results demonstrated that the introduction of Welan gum significantly increased the strength of the foam and improved its rheological properties. The Welan gum-enhanced foam (WG-foam) exhibited higher flow resistance in fractured reservoirs, resulting in enhanced oil recovery. Compared to traditional hydrophobically associating polymer-enhanced foam (HAPAM-foam), the WG-foam showed a remarkable half-life for drainage of 20 h, which is 13 times longer than that of HAPAM-foam. Furthermore, the ultimate oil recovery of WG-foam was 21% higher than that of HAPAM, reaching 87%. Through molecular dynamics simulations, we uncovered the exceptional water-binding capacity of Welan gum, which significantly delayed the drainage rate in the foam lamella, thus enhancing foam stability. This work not only provides a powerful technical approach for foam-enhanced oil recovery, but also offers new insights into the fabrication of high-performance foams.