Research on the distribution characteristics of a novel oil displacement system for conformance control in microporous media

Abstract

This study aims to investigate the distribution characteristics of a novel hydrogel system (HDS) for in-depth conformance control. Through a combination of static gelation experiments and core flow experiments, the thickening performance and seepage characteristics in porous media of the novel HDS system was studied. Considering the viscosity changes and dynamic chain extension reactions of the HDS system, the Darcy-Brinkman-Stokes (DBS) micro-continuum approach was applied to develop a multi-physical mathematical model for the migration of HDS system in a pore-throat network. Therefore, a 4-meter core experiment and multi-scale numerical modeling were conducted to analyze the dynamic chain extension efficiency and spatial distribution characteristics of the HDS system. Additionally, machine learning techniques were used to define the dynamic chain extension reaction index (RI) and identify its critical threshold, exploring the effects of varying injection parameters, solution concentrations, and permeabilities on the chain extension behavior. Results show that HDS molecular chains form aggregated structures that evolve into a unique spatial network. As the network structure becomes denser, the viscosity of HDS system increases rapidly. As the core permeability increases, the core throat size enlarges, and the compatibility between the HDS system molecular aggregates and the pore throat improves. HDS system shows good transmission performance during migration in the long core. Numerical simulations and machine learning techniques were employed to define the dynamic chain extension RI, examining how RI changes under varying injection parameters, solution concentrations, and permeabilities. As permeability, HDS system concentration, and injection rate increase, the RI also increases. The results are presented in the RI graph, offering theoretical insights for deep profile adjustment and the development of reagent systems.