Tariq Ali Chandio

This study presents the utilisation of Propylene Carbonate (PC), along with an alkali-based solution, to modify the Hydroxyethyl Methyl Cellulose (HEMC) polymer to mitigate the thermal degradation of cellulose ether. The experimental results from FTIR and XRD analysis confirmed the addition of a new function group to the HEMC backbone and the formation of a new organic carbonate-based cellulose ether. Shear viscosity experiments were conducted at concentrations of 0.50-wt.% to 2-wt.% at ambient and elevated temperatures ranging from 80°C-110°C using a rheometer. All polymeric solutions exhibited shear-thinning behaviour, and the viscosity of polymeric solutions was enhanced by increasing the concentration of modified HEMC solutions. The modified HEMC solutions exhibited higher viscosity at 1000 s-1 shear rate at 110ºC compared to the native HEMC solutions, confirming the enhanced thermal stability of the PC-based modified HEMC solution. Alkali-based modified HEMC solution exhibited low shear viscosity at ambient temperature. The alkali-based polymeric solution’s viscosity was increased by 48% at a high shear rate at 110ºC. In conclusion, 0.50-wt.% and 01-wt.% concentration of alkali-based PC-modified HEMC solution proved efficient in maintaining viscosity under ambient conditions, increasing solubility and exhibiting improved thermal stability at geothermal conditions for oil field applications.

Nanofluids as an EOR technique are reported to enhance oil recoveries. Among all the nanomaterial silica with promising lab results, economic and environmental acceptability are an ideal material for future applications. Despite the potential to enhance recoveries, understanding the two-fold impact of parameters such as concentration, salinity, stability, injection rate, and irreproducibility of results has arisen ambiguities that have delayed field applications. This integrated study is conducted to ascertain two-fold impacts of concentration and salinity on recovery and stability and evaluates corresponding changes in the recovery mechanism with variance in the parameters. Initially, silica nanofluids’ recovery potential was evaluated by tertiary flooding at different concentrations (0.02, 0.05, 0.07, 0.1) wt. % at 20,000 ppm salinity. The optimum concentration of 0.05 wt. % with the highest potential in terms of recovery, wettability change, and IFT reduction was selected. Then nano-flooding was carried out at higher salinities at a nanomaterial concentration of 0.05 wt. %. For the mechanism’s evaluation, the contact angle, IFT and porosity reduction, along with differential profile changes were analyzed. The recovery potential was found at its highest for 0.05 wt. %, which reduced when concentrations were further increased as the recovery mechanisms changed and compromised stability. Whereas salinity also had a two-fold impact with salinity at 30,000 ppm resulting in lower recovery, higher salinity destabilized the solution but enhanced recoveries by enhancing macroscopic mechanisms of pore throat plugging.