The effect of methylene blue and organic acids on the wettability of sandstone formation: Implications for enhanced oil recovery

Abstract

Fossil fuels are the primary global energy source, and their improved production will ensure a balance between the increasing energy demand and supply. Chemical-enhanced oil recovery has been well thought of as a promising method for increasing hydrocarbon production. However, the effectiveness of this method depends on wettability of rock-oil-brine systems’ Previous studies have shown that oil-wet rock demonstrated a water-wet state when treated with surface active chemicals like surfactants, nanofluids. Moreover, increasing attention has become focused on the application of hazardous pollutants such as methyl orange and methylene blue to enhance the CO2/H2 containment security of the host rock by altering its wettability. Nevertheless, the capacity of methylene blue to modify the rock wettability for the production of trapped hydrocarbons in sandstone reservoirs is yet to be explored. Thus, in the present study, methylene blue is used as a wettability modifier to enhance the oil production from quartz rocks that have been aged with stearic acid solution (10-2 mol/L). First, the organic-aged quartz is treated with various concentrations of methylene blue (10-100 mg/L) for one week at 60 °C. Then, contact angle measurements are performed at different temperatures (25 and 50 °C) under various pressures (10-20 MPa) and brine salinities (0-0.3 M). Thus, the quartz is found to turn hydrophobic when aged in organic acid/n-decane solution at 20 MPa and 50 °C. However, when the rock is treated with various concentrations of methylene blue, the hydrophobicity is found to decrease, thus suggesting that oil recovery will be promoted by methylene blue treatment. Overall, the results demonstrate that the most favourable condition for reducing the hydrophobicity of the sandstone rock is via treatment with 100 mg/L methylene blue. Hence, the injection of methylene blue into deep underground sandstone reservoirs has the potential to produce more residual hydrocarbons.

Document Type: Original article

Cited as: Alhammad, F., Ali, M., Yekeen, N. P., Ali, M., Hoteit, H., Iglauer, S., Keshavarz, A. The effect of methylene blue and organic acids on the wettability of sandstone formation: Implications for enhanced oil recovery. Capillarity, 2024, 10(2): 29-37. https://doi.org/10.46690/capi.2024.02.01