Stability of novel cellulose-nanofiber-containing foam as environmentally friendly fracturing fluid

Abstract

Foam-based fracturing is one of the waterless fracturing technologies that can reduce the environmental issues of water-based fracturing. To utilize foam as a fracturing fluid in oil/gas developments, improving foam stability is essential. To examine whether the environmentally friendly and low-cost cellulose nanofiber (CNF) can be a novel foam stabilizer, we investigated the effect of surfactant on the initial foam volume and stability of CNF-containing foam using four types of surfactants with different electrical properties. Then, we investigated the stability of CNF-containing foam under the high-pressure or high-temperature conditions as well as under the laboratory pressure and temperature condition and compared to the stability of foam containing sodium salt of CMC (NaCMC). In addition, we investigated the stability of CNF-containing foam under the presence of salts. As a result, it was concluded that the initial foam volume and stability of CNF-containing foam strongly depend on the type of surfactant because the CNF surface is negatively charged; the CNF is superior to NaCMC as a foam stabilizer, especially in the CNF concentration range above 0.10 wt%; the stability of CNF-containing foam decreases with increasing temperature and increases with increasing pressure, and it is significantly reduced with the addition of salt because the aggregation of the CNFs is formed due to the interaction between the salt cations and CNFs. Further research is expected to use CNF as a stabilizer for foam-based fracturing fluids as CNF is an attractive biomass substance as a foam stabilizer.