Dynamic gel-forming properties of cardanol modified phenolic resin gel system in long snake-like simulation core with heterogeneity matching actual reservoir conditions

Abstract

ABSTRACT Gel system consisting of polymer and phenolic resin cross-linker commonly used for water shutoff is not environmentally friendly enough, and the homogeneity of the simulation core has important influence on the experimental results for evaluating the gel properties in the laboratory. In this paper, a modified cross-linker was obtained by substituting cardanol for phenol in the conventional cross-linker. Environmentally-friendly gel was prepared with polymer and cardanol modified cross-linker. A long snakelike core physical simulation system with multiple nonvolatile fluid sampling ports and core sampling ports was developed by connecting curved sand-packed pipes with straight pipes, and it was used to evaluate the dynamic gel-forming properties of the modified gel. The results showed that the strength and stability of the modified gel were not inferior to those of conventional gel. By intelligently controlling the applied force, the long snakelike core had a heterogeneity that matched the actual formation conditions. When injecting gel-forming solution using modified cross-linker into the snakelike core with porosity of 37.6% and permeability of 16.98 μm2, as the increase of the distance between the sampling port and the injection end, the viscosity of the system formed by placing the sampled gel-forming solution at 45°C for 24 hours decreased but remained consistently above 1000 mPa·s. The gel-forming solution could still form gel dynamically after migrating to 10.2 meters, thereby achieving effective plugging. The proposed long core in this work is helpful to study whether the gel systems can dynamically regulate the deep part of the reservoir, providing guidance for improving the macroscopic application properties of cardanol modified gel and promoting sustainable development for oilfields.