Ab initio and molecular dynamic simulation of betaine viscoelastic surfactants behavior in presence of ferricchloride ions and its influence on stimulation treatment

Betaine viscoelastic surfactant has a wide range of application in oilfield industry including fracturing fluids, gravel packing, acid treatments, completion fluids, drilling fluids and in applications such as permeability modification, etc. The effect of ions can be detrimental on the properties of betaine solution. Understanding how macroscopic properties depend on intermolecular interactions for complex fluids is the main focus of this study. The objective of this paper is to use first principle approach in studying interaction between different head groups with chloride and ferric ions. Density functional theory (DFT) and classical molecular dynamics (MD) simulations are employed to better understand how Cl- and Fe3+ ions can impact physical properties of viscoelastic surfactants and hence their functionality in stimulation treatment. Complexation of ferricchloride [FeCl4]- with betaine headgroups was also investigated to explain possible mechanism result in formation damage and surfactant precipitation at high ferric concentration (>10,000 ppm).