Multi-scale Analysis of Surfactant-assisted Enhance Oil Recovery and Carbon Dioxide Geological Utilization
Creators: name: Liu, Benjieming
Publisher: name: Graduate Studies
Year: 2024
Subjects: subject: Surfactant
subject: wettability
subject: miscibility
subject: carbon neutrality
subject: molecular dynamics simulation
subject: reservoir simulation
subject: Engineering--Petroleum
subject: Engineering--Chemical

description: Ever since the first industrial revolution, the rising trend of energy consumption and greenhouse gas (GHG) emissions never stopped, contributing to the pressing global issue of global warming. The society still has a chance to prevent the worst of climate change’s future harm. Therefore, balancing the increase in energy demand while controlling carbon dioxide (CO2) emissions has become a common goal for humanity. In the oil and gas industry, surfactants have been recently regarded as a viable chemical additive to enhance oil recovery (EOR) and carbon capture, utilization, and storage (CCUS). However, the performance of surfactants in engineering fields has often been assessed too simplistically based on observed changes in their behaviors or properties. In order to provide an in-depth fundamental understanding of surfactant-assisted EOR and CCUS processes across multiple scales, in this thesis, essential mechanisms, including displacing performance, adsorption, diffusion, wettability, miscibility, and feasibility in field applications, were studied by experimental methods, molecular dynamics (MD) simulations, and numerical reservoir simulations. In detail, a) the impact of clay minerals on oil detachment from quartz surfaces during surfactant-assisted thermal recovery processes was evaluated; b) a generalized surface modeling procedure of wettability transition on quartz surfaces was proposed to accurately predict a contact angle on sandstone formations; c) the effect of nanoconfinement on the minimum miscibility pressure (MMP) of a CO2/shale oil/surfactant system was investigated; d) a feasibility case study of a novel CO2-switchable surfactant flooding project was conducted on a targeted reservoir. The results of this thesis proved the versatility of surfactants in EOR and CCUS. It is found that clay minerals are not always detrimental to oil recovery. In fact, some clay contents can enhance an oil detachment process by influencing a spatial distribution of surfactant molecules in nanopores. The proposed generalized surface modeling procedure of quartz wettability in this thesis provided more accurate results than a traditional treatment that fully hydroxylates surface atoms. It successfully captured the trend of wettability transition on a quartz surface while considering a series of parameters, including a surface hydroxyl group density, temperature, surfactants, and crude oil. It was also found that the presence of surfactants can reduce the CO2-shale oil MMP. MMP can be further decreased when considering the nanoconfinement effect, as it intensifies CO2-surfactant interactions and inhibits the tendency of CO2 molecules to self-aggregate. Additionally, applying a CO2-switchable surfactant in chemical flooding significantly increased oil recovery, offering an eco-friendly method for oil production. To conclude, this dissertation deepens the understanding of surfactants in EOR and CCUS at multiple scales. It provides helpful guidance on surfactant-assisted engineering processes in the chemical and petroleum industry.