Case Study of Asphaltene Flow Assurance Risk Mitigation - Emerging Numerical Model to Evaluate Inhibitor Efficiency

Abstract

Summary This work was motivated for establishing a robust asphaltene flow assurance engineering in an onshore oil field that has a high risk of asphaltene precipitation in tubing. A typical counter measure was considered to apply asphaltene inhibitor, therefore, the best candidate IB-23 was selected through the two staged asphaltene dispersant test (ADT) from total nineteen samples. The IB-23 revealed high inhibiting efficiency more than 80 % at 200 ppm concentration and maintained its efficiency more than 70 % even at 10 ppm. For further evaluating persistent of inhibiting efficiency during entire field life in which operating condition in tubing is varied, an emerging technique was developed to numerically model inhibitor. Currently, any commercial software is not available for allowing such modelling of asphaltene inhibitor due to confidentiality for inhibitor’s physical data. This study achieved to model inhibiting efficiency by treating inhibitor as pseudo-resin. It could be defined using limited physical data that was available in public accessible material safety data sheet (MSDS). Consequently, the inhibiting efficiency was expressed as size-reduction of asphaltene precipitation envelope (APE) on thermodynamic plot. Comparison between APEs and vertical lift curves could provide a comprehensive prediction of the inhibitor effect at early and late field life.