Enhanced flow diversion using combined nanoparticles and biodegradable zwitterionic viscoelastic surfactants

Abstract

Efficient oil recovery in low-permeability reservoirs is often hindered by the inability of hydrocarbons to migrate from the matrix to the wellbore. To address this challenge, petroleum engineers utilize viscoelastic surfactant (VES)-based diverters for any injection by the purpose of Well Stimulation or Enhanced Oil Recovery (EOR), particularly in reservoirs with complex permeability variations. VES molecules self-assemble into worm-like micelles (WLMs) at concentrations above a critical micelle concentration (CMC), forming dynamic networks that impart viscoelasticity and enhance fluid diversion efficiency. This study introduces a novel approach by optimizing an Environmentally Friendly, Biodegradable, and Cost-Effective Zwitterionic VES formulation through nanoparticle incorporation, enabling a reduction in VES concentration (2 and 3 wt% instead of 6 wt%) while maintaining or enhancing performance. Key innovations include (1) improving the rheological properties of VES, (2) reducing chemical usage by integrating nanoparticles, and (3) employing micromodel screening to minimize costly core-flooding experiments. Experimental evaluations examined the impact of colloidal silica (SiO2) and magnesium oxide (MgO) on zwitterionic VES solutions under standard oilfield brine conditions. Results demonstrated that SiO2 significantly improved viscosity retention and thermal stability up to 95 °C, whereas the MgO-VES combination failed to meet performance criteria. Notably, SiO2-enhanced VES successfully diverted over 81 % of the injected fluid from high- to low-permeability zones, underscoring its potential for optimizing oil recovery in heterogeneous reservoirs. This study provides a cost-effective and thermally stable VES formulation, offering a promising solution for fluid diversion in complex reservoir conditions.