A New Effective Multiwalled Carbon Nanotube-Foam System for Mobility Control

Abstract

Nanoparticles have improved a surfactant's ability to create long-lasting foam. Recent studies have widely recommended the use of silica nanoparticles to enhance foam stability. This paper presents an experimental investigation of a new and highly effective Alpha Olefin Sulfonate (AOS)-multiwalled carbon nanotube (MWCNT) system for mobility control during gas EOR operations. The new AOS-MWCNT system was evaluated for its foam stability at 150°F using a high-pressure view cell. The MWCNT was obtained as solid particles of aspect ratio up to 100 and silica nanoparticles of median size 118 nm. The foam system was optimized for its maximum half-life by varying the concentration of the AOS and the nanotube from 0.2-1% and 250-1,000 ppm, respectively. Compatibility testing with salts were done as well. Coreflood experiments with 1.5 in. diameter and 6 in. long Berea sandstone cores were run to calculate the mobility reduction factor at 150°F. Nitrogen foam was injected into the core at 80% foam quality in the tertiary recovery mode and the pressure drop across the core was measured. The formation brine had a salinity of 5 wt% NaCl and the foaming solutions were prepared with 2 wt% NaCl. The optimal concentrations of the AOS solution and the nanotubes for maximum foam stability were determined to be 0.5% and 500 ppm, respectively. The optimized AOS-MWCNT system yielded 70% greater nitrogen foam half-life (32 minutes) than an optimized AOS-silica system at 150°F. The foam half-life of a standalone 0.5% AOS solution was 7 minutes. In presence of crude oil, the foam half-life decreased for all the tested systems. Coreflood experiments at 150°F showed a significant increase in the mobility reduction factor when the new AOS-MWCNT system was used as the foamer instead of standalone AOS or AOS-silica system. The new foaming system was stable through the duration of the experiment, yielding foam in the effluent samples. There was no formation damage observed. Salt tolerance for the MWCNT nanofluid was higher than the silica nanofluid. Foam needs to be stable for long periods of time to ensure effective mobility control during gas injection for EOR. This paper investigates a new highly effective AOS-multiwalled carbon nanotube system that outperforms the AOS-silica foaming systems in terms of foam stability and mobility control at 150°F.

Insights into CO2 Foaming Behavior of Ethoxylated Amines

“…The molecular weight of the surfactant was 270 g/mol. The density and viscosity of the surfactant were 0.9 g/cm 3 and 120 cP, respectively. The surfactant solutions were prepared with a salinity of 0-25 wt% sodium chloride and a surfactant concentration of 0.0001-2 wt% using deionized water with a resistivity of 18.2 MΩ-cm at room temperature.…”

“…In foam-assisted CO 2 EOR, the mobility of CO 2 is reduced by increasing the apparent viscosity of the gas phase, stabilizing the displacement process and increasing the sweep efficiency. Moreover, through the formation of foam in high permeability zones/layers, the technique achieves conformance control for CO 2 EOR [2,3]. Gravity segregation, another problem of CO 2 EOR, is also alleviated when foam is applied by shifting the viscous/gravitational force competition [4].…”

From initial treatment design to final disposal of chelating agents: a review of corrosion and degradation mechanisms

“…The corrosiveness of various APCAs on metals has been widely studied as they are usually used as alternatives to the traditional HCl acidizing formulations at high temperatures. 47 APCAs are often used at pH 4 for standalone acidizing. Therefore, understanding chelating agent corrosion is vital when designing the treatment.…”