Experimental investigations to evaluate surfactant role on absorption capacity of nanofluid for CO2 utilization in sustainable crude mobilization

Carbon dioxide (CO2) utilization for oilfield applications is affected by viscous fingering which leads to premature breakthrough without showing any appreciable impact on oil recovery and storage. Therefore, to control these issues, CO2 is often injected with high viscous fluid i.e. nanofluid. However, nanofluid efficacy can be further improved by inclusion of a surfactant that not only increases specific area of CO2 [via interfacial tension (IFT) reduction] but also increases CO2 absorption capacity of nanofluid through formation of foam. Thus, in this study, a new colloidal solution of anionic surfactant (i.e. sodium dodecyl sulfate, SDS, 0.16-0.24 wt%) and polymer based single-step silica nanofluid of varying concentration (0.1-1.0 wt%) was proposed for subsurface carbon utilization in CO2 absorption, IFT reduction, and fossil fuel displacement. CO2 absorption experiments showed that absorption was positively influenced by pressure and NP concentration, while increasing temperature showed reverse impact on CO2 absorption. In addition, SDS ensured formation of a Pickering foam which made CO2 to retain inside for over 10 days (an increase of 67%) in SDS treated nanofluid, higher than 6 days of simple nanofluid. Pickering CO2 foam of SDS treated nanofluids was also envisaged for IFT reduction of crude oil, to identify role of these nanofluids in crude mobilization from porous reservoir. CO2 absorption capacity of nanofluid exhibited inverse relationship with IFT value of crude oil. Finally, displacement experiments were conducted which also support inclusion of SDS in silica nanofluid for reduced water cut and higher fossil fuel recovery from porous media. Initially, the oil recovery was only 42% with water and 52% with 1 wt% NP concentration. However, the highest oil recovery was 61% when 1 wt% NP/0.16 wt% SDS combination was used. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The utilization of CO2 for oilfield applications is affected by viscous fingering, which can be controlled by injecting CO2 with high viscous nanofluid. Adding a surfactant to the nanofluid further improves CO2 absorption and retention capacity. Experiments show that the combination of surfactant and nanofluid can enhance oil recovery and reduce water cut in porous media.