Experimental Investigation on Corrosion and Emulsification During CO2 Injection in Heavy Oil Reservoirs

Abstract

ABSTRACT Carbon dioxide (CO2) injection possesses an immense potential for production improvement in heavy oil reservoirs. The primary interest of this work is to investigate the corrosion effect of carbonated water formed by CO2 and formation water on reservoir rock, and the emulsification of crude oil. This study used the scanning electron microscope and interfacial tension (IFT) setup to research the core micro-structure and oil-water IFT. The results showed that the corrosion ability of carbonated water gradually increased as pressure increased within a certain range of pressure. When the pressure increased from 8MPa to 16MPa, the average corrosion rate increased from 0.45% to 0.66%. Moreover, the injection of CO2 caused the appearance of corrosion pits and cracks, surface particles peeled off and dissolved, and cracks extending as pressure increased. The dynamic IFT between the decyl trimethyl ammonium bromide solution and crude oil changed less and stabilized in less quickly without CO2 injection. The dynamic IFT decreased faster with pressure increase after CO2 injection, which was favorable for crude oil emulsification and emulsion stabilization. There is a positive correlation between Equilibrium IFT and temperature at the condition of low temperature. INTRODUCTION The global heavy oil resources are abundant. The proven recoverable heavy oil resources are 126.74 billion tons, 71% of which are distributed in the Americas and the Middle East (Liu et al., 2019; Shah et al., 2010). The key to exploiting heavy oil is to reduce viscosity and improve fluidity(Al-Samhan et al., 2022; Wang et al., 2023). Thermal recovery is the most commonly used method for heavy oil extraction at home and abroad (Bueno & Mejía, 2022). However, in heavy oil thermal recovery, the large reservoir depth, strong formation heterogeneity, and high crude viscosity, will lead to low thermal energy utilization, high development cost, and low extraction efficiency (Khelkhal et al., 2022). CO2 is a commonly used replacement medium, with various special mechanisms such as replenishing formation energy, reducing crude oil viscosity, extracting light components and blending (Kumar et al., 2022). Meanwhile, CO2 as a greenhouse gas seriously impacts on global climate, and CO2 utilization and storage can effectively reduce carbon emissions, so CO2 is of great significance for thick oil development (Lan et al., 2019).