MITIGATING CLAY SWELLING AND PERMEABILITY LOSS IN THERMAL EOR WITH A QUATERNARY AMMONIUM CLAY STABILIZER UNDER HIGH-TEMPERATURE LOW-SALINITY CONDITIONS

Abstract

Clay swelling and fines migration pose major challenges to thermal enhanced oil recovery (EOR), especially in clay-rich reservoirs like the East Moldabek Field in Kazakhstan. While previous studies offer limited solutions under high-temperature, low-salinity (HTLS) conditions, this study addresses this gap by evaluating three different clay inhibitors to mitigate formation damage. Through static swelling tests, a quaternary ammonium-based inhibitor demonstrated superior performance via ion exchange and surface charge stabilization. Among the inhibitors tested, it achieved the highest permeability retention maintaining 48.89% in distilled water at 100°C, compared to only 17.05% in untreated samples. It also reduced the Critical Salt Concentration (CSC) from 7380 ppm to 4920 ppm. Scanning Electron Microscopy (SEM) confirmed structural integrity in treated clays, contrasting with severe delamination in untreated samples. Dynamic core-flooding tests further validated its effectiveness by reducing pressure drops, minimizing fines migration, and enhancing permeability retention under HTLS conditions. Performance decreased in high-salinity environments due to natural ionic stabilization. While field-scale studies are needed to assess long-term performance and economic viability, the quaternary ammonium inhibitor offers a promising solution for controlling clay swelling, preserving permeability, and improving thermal EOR efficiency in challenging reservoir conditions.