Near-Wellbore Salinity Effect on Sand Control Plugging by Fines Migration in Steam-Assisted Gravity Drainage Producer Wells

Abstract

Sand control screens are necessary for steam-assisted gravity drainage (SAGD) wells drilled into oil sands to prevent sand production. However, the accumulation of mobilized fine particles near the wellbore can result in screen plugging, adversely affecting the well's flow performance. This research assesses the effects of formation water salinity on fines migration and the flow performance of sand control screens in SAGD wells. The study primarily examines these effects through sand retention testing (SRT) conducted under representative rock and multi-phase flow conditions. This research developed a novel SRT methodology, which implemented the salinity effect in multi-phase flow through sand pack and sand control screen. Two sand retention tests were designed using identical procedures in two-phase fluid flow (oil and brine), flow rate, and water cut. The first test used constant salinity, emulating existing SRT procedures in the literature. The second test, however, used gradually reducing salinity levels to emulate declining salinities around SAGD production wells caused by the flow of condensed steam. The results indicated a significant decrease in the retained permeability of the screen coupon due to fines migration triggered by the reduction of salinity. Single-phase oil flow stages did not show noticeable produced fine particles at the outlet. In two-phase flow conditions, high flow rate and water cut stages induced higher produced fine particles under constant salinity, reflecting the hydrodynamic effects in fines migration. However, observations confirmed that a substantial mass concentration of fine particles was mobilized, retained, and produced by reducing salinity. The findings of this study reveal the importance of the salinity effect on fines migration and the flow performance of SAGD wells where high saline formation water is diluted by low saline condensate steam. Testing results indicate the necessity of incorporating the chemical effects in sand retention tests. Further research considering high-pressure and high-temperature conditions around SAGD wells and interactions with other formation damage mechanisms would extend this research.