Foam stability is a crucial consideration in the view of its numerous applications. Herein, a series of nanocellulose fibrils containing lignin segment (L-NCF) was designed and then utilized for interfacial stabilization of liquid foams for eco-friendly oil recovery applications. The ability to form foams and their stability at bulk scale and bubble scale were thoroughly investigated using a foam scanner. Liquid drainage rate, bubble rupture, interfacial dilational viscoelasticity, and bubble transport in porous media were studied as a function of lignin content. We observed that in a vertical column the addition of L-NCF significantly mitigated the drainage of the liquid foams. The foam volume stability (FVS) index indicated that the stability of the foams in the presence of L-NCF was up to five times higher than that of surfactant-only foam. The hydrophobic interaction between the surfactant (mixture of alkyl polyglycoside (APG) and anion surfactant alpha olefin sulfonate (AOS)) and L-NCF (lignin segment) constructed an elastic interface for the foams, which notably protected the liquid foams from coarsening and coalescence. The L-NCF stabilized foams can appropriately transport in porous media without the plugging issue, during which great differential pressures are simultaneously built up as a result of the yielded elastic interface. It is believed that nanocellulose is very promising in the oil production industry as a green alterative to synthetic chemicals.
The depression of the current global oil market makes the majority of chemical EOR projects worldwide nearly unprofitable, especially in China. Therefore, economic alternative methods and technologies must be quickly developed. This proof of concept research evaluates a chemical flooding method using pre-formed mild O/W emulsions, which were produced by saponification between a low-cost alkali (NaOH) and a petroleum acid-rich oil. Our focus was first given to the dynamics of the saponification with an aim to quantify alkali consumption. Afterward, the composition of the crude oil before and after the reaction was characterized using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) to determine the preferred compounds in saponification. The physiochemical properties of the generated emulsions were further investigated through direct measurements of rheology, morphology, particle size distribution, and stability. Particular attention was placed on the oil displacement mechanisms of the emulsions at pore level. The results showed that fatty acids, naphthenic acids, and aromatic acids were clearly partitioned on the FT-ICR MS spectra of the crude oil, while the C16 and C18 fatty acids (DBE = 1, DBE represents equivalent double bond number) were predominantly saponified, which accordingly produced mild O/W emulsions (pH ≈ 7.0). The viscosity, morphology, and stability of the emulsions were found to strongly depend on the oil–water ratio. The displacement dynamics of three stable emulsions observed in a visual micromodel revealed that the O/W emulsion flooding can enlarge the sweep area and also notably reduce the residual oil saturation when employed as an EOR mode. Emulsification/entrainment, blocking, and stripping were three dominant pore level driving forces for this emulsion flooding. Phase inverse from O/W to W/O occurred when the emulsion of O/W = 3:7 was used and finally caused injectivity issue.
Conformance control in fractured tight formations remains a challenge because of large permeability contrasts between fractures and the matrix. Therefore, there is an emerging interest in particle gels that possess favorable mechanical properties and low production costs. To address this issue, we proposed a kind of nanocellulose-strengthened particle gel, named NC-st-PG, which was prepared by sparsely interpenetrating cellulose nanofibrils (NCF) and nanocrystals (NCC) respectively into a polyacrylamide (PAAm) matrix. The characteristics of NC-st-PG from the chemical structure to mechanical and thermal stability were investigated thoroughly. We noted that the PAAm network was noticeably strengthened and toughened by introducing stiff NC segments without compromising the elasticity of the gels. The optimum amount of NCF and NCC in the PAAm was found to be 0.1 wt %. We cycled the deformation and observed that NC-st-PG exhibited fatigue-resistance and remained highly elastic after 10 cycles of stress load and unload. In addition, the swelling and thermal decomposition of NC-st-PG were restrained by the presence of NCC and NCF. These characteristics render NC-st-PG superior stability under consecutive shearing in fractures and are indicative of the efficiency and durability of conformance treatment using NC-st-PG. The results of this study supplement earlier observations and provide an alternative to conventional gels to address conformance issues in tight formations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.