Investigation of Asphaltene Instability Under Gas Injection in Unconventional Reservoirs and its Impact on Oil Recovery Performance
"Unconventional reservoirs, such as shale gas and tight oil formations, have become an important source of energy in recent years. However, these reservoirs often contain high levels of asphaltenes, which can lead to deposition and blockages in production wells and reduce the flow of hydrocarbons during gas enhanced oil recovery (GEOR) techniques. This study aims to experimentally evaluate the impact of miscible and immiscible carbon dioxide (CO₂) and nitrogen (N₂) on asphaltene deposition and its impact on oil recovery performance in unconventional shale reservoirs. This research began with a comprehensive literature review and data analysis of GEOR methods in unconventional reservoirs. Following this, the minimum miscible pressure of CO₂ and N₂ was determined using the slim tube technique. Two gas injection methods were implemented in this research, including continuous and cyclic (huff-n-puff) modes. In the continuous mode, filter paper membranes which represent shale structure were utilized to demonstrate the severity of the asphaltene deposition rate under different scenarios. For the huff-n-puff mode, various Eagle Ford shale cores were used to understand the potential of this mode on asphaltene instability in real shale structures and its influence on oil recovery performance. The plugging impact of asphaltene particles in continuous mode was evaluated using various methods including optical microscopy and scanning electron microscopy (SEM) imaging. Chromatography analysis of crude oil, wettability alteration, and pore size distribution were used to validate and support the findings of this research"-- Abstract, p. iv
Asphaltene deposition, asphaltene instability, enhanced oil recovery, minimum miscible pressure, miscible and immiscible gas injection, unconventional shale, Chemical Engineering, Engineering, Petroleum Engineering
Missouri University of Science and Technology
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