Encapsulation of xanthan gum for controlled release at water producer zones of oil reservoirs

Abstract

Tolerating the harsh conditions of reservoirs is one of the main challenges for the application of chemicals in field operations. Polymers are one of the chemical agents with extensive utilization in reservoirs. They could be used to control water conformance, though there are some limitations like low thermal tolerance and low chemical stability, which restrict their applications. To overcome these limitations, encapsulation of xanthan gum by silica nanoparticles and lecithin has been investigated in this research. Using the inverse emulsion method, xanthan gum is encapsulated and the stability of capsules at various conditions is assessed. It is illustrated that the stability of silica-shelled capsules is greater than that of lecithin. Based on the results of this study, the encapsulation of xanthan gum improved its thermal resistivity. Besides, formed capsules reflect fair stability against high salinity conditions. Finally, the formed capsules were injected into two artificial Berea sandstone cores and it was found that the lecithin-shelled capsules can reduce the permeability of cores up to 92%. Silica-shelled capsules are also capable of blocking the porous medium partially and reduce the permeability by around 33%.