Controlled Release of Amphoteric Surfactant from Mesoporous Nanosilica To Enhance Natural Gas Production at High Temperatures.

ABSTRACT

Surfactants are widely used as foaming agents to remove liquid accumulation in gas wells, enhancing natural gas production. The surfactant used in traditional foam sticks was dissolved and released as foam in a short period, especially at elevated downhole temperatures. This often requires the addition of foam sticks to maintain foam. To solve this problem, this study studies the utilization of nano silica to incorporate the amphoteric surfactant, cocamidopropyl betaine (CAB), into the mesoporous structure of silica nanocomposite as foam sticks for controlled release of CAB. Mesoporous nano silica was prepared by a sol-gel acid-catalyzed process with a silica precursor. The formation of nanocomposite solid sticks containing the amphoteric surfactant was achieved by aging and drying. The composite was characterized by various techniques infrared spectroscopy, thermogravimetric analysis, energy-dispersive spectrometry, scanning electron microscopy, transmission electron microscopy, and small-angle X-ray diffraction. Results showed that 49.3% of CAB was encapsulated within the mesoporous structure of 30-50 nm nano silica. CAB release over time in aqueous solution at 130 °C exhibited 10.1% surfactant left in the nanocomposite after 72 h, as determined by thermal analysis. Surfactant release was systematically evaluated through foam performance tests. The study revealed that CAB could be control-released over 168 h via CAB diffusion from mesoporous silica. This study provides a longer-lasting foam method to enhance gas production by utilizing mesoporous silica as a control release medium for gas well deliquification.