High Throughput Prescreening of Asphaltene Chemical Inhibitors Using Molecular Dynamics Approach

Choosing an effective chemical inhibitor to prevent asphaltene precipitation and deposition in oil reservoirs is crucial for flow assurance management in the oil industry. Traditional laboratory screening methods are time-consuming and expensive. Therefore, we propose an alternative, which is employing molecular dynamics (MD) simulations for efficient prescreening of asphaltene inhibitors. In this study, MD is employed to screen six potential inhibitors, including cetyltrimethylammonium bromide (CTAB), octylphenol (OP), Triton X-100, 1-butyl-3-methylimidazolium bromide ([BMIM][Br]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), and 1-octyl-3-methylimidazolium chloride ([OMIM][Cl]). The results conclude that CTAB has the highest inhibitory effect on asphaltene precipitation in n-heptane and heptol at both atmospheric and elevated thermodynamic conditions (pressure of 60 bar and temperature of 360 K). OP is selected as the second-ranked inhibitor in n-heptane, while Triton X-100 prevents asphaltene precipitation better than OP when heptol is the carrying fluid. Ionic liquids show weaker inhibitory effects compared to surfactants. Nevertheless, [OMIM][Cl] is selected as the best ionic liquid to prevent asphaltene precipitation in n-heptane at atmospheric conditions, while [BMIM][Cl] is selected as the best one in heptol. Hence, inhibitor screening tests for asphaltene precipitation consistently demonstrate CTAB as the most effective inhibitor. Subsequently, the CTAB performance is studied on the prevention of asphaltene deposition in a calcite pore. The results show that the presence of CTAB reduces the asphaltene deposition by about 30%. The lab scale cost ranking of inhibitors, from low to high, is as follows: Triton X-100, CTAB, [BMIM][Cl], [BMIM][Br], [OMIM][Cl], and OP. This shows CTAB has economic benefit over the others, while further field scale cost evaluation is needed before a final decision. This research introduces a cost-effective and efficient screening method for selecting chemical compounds based on molecular interactions. The introduced method for inhibitor screening is less expensive and faster than regular experimental approaches, while it provides proven accuracy compared with experimental techniques.