Controlled releases of asphaltene inhibitors by nanoemulsions

Asphaltene precipitation is usually responsible for many flow assurance problems such as wettability changes and pore clogging in reservoirs, fouling in wellbore tubing and production surface facilities. This study develops a novel approach by using nanoemulsions (NE) for controlled delivery and release of asphaltene inhibitors (AI) to minimize asphaltene precipitation with reduced AI amount. LUMiSizer was utilised to study the effectiveness and performance of controlled release by three cases on asphaltene sedimentation: i) strong organic acids (dodecyl benzene sulfonic acid, DBSA), ii) nanoemulsions (blank NEs), and iii) nanoemulsions loaded with DBSA (DBSA NEs). The experiments suggested that the optimum inhibitor concentration for completely stabilizing asphaltene were 4 vol% for DBSA. This amount of inhibitor can be significantly reduced by ∼20 times by using the DBSA NEs, and the release time can be greatly extended. A mechanistic understanding of the controlled release effect is proposed based on interfacial properties and electron microscopic studies, which is related to the hydrophilicity of DBSA and the strong intermolecular interactions among all DBSA NE's components and the asphaltene molecules.