Application of Raman spectroscopy for analyzing the behavior of gases in sandstone reservoirs

The behavior of gases within subsurface pores determines the oil and gas recovery and CO₂ storage in the region. In this study, we report a novel method based on Raman spectroscopy for observing the distributions of CH₄ and CO₂ gases in the pores of sandstone reservoirs. First, we designed a pressure-cell to inject gases into a sample. Then, CH₄ and CO₂ gases were injected into the sample using the pressure-cell placed on the Raman spectroscopy system sample stage. Quartz and feldspar were the predominant minerals in the sample. The CH₄-occupied pores exhibited a Raman peak at 2917 cm⁻¹. Two-dimensional (2D) and three-dimensional (3D) mapping of the pores depicted the geometry of the CH₄ gas-filled pores. After injecting CO₂ gas, we observed an intensity peak at 1388 cm⁻¹; we obtained 2D and 3D maps of the CO₂ gas-filled pores based on this peak value. This study demonstrates the potential use of Raman spectroscopy as a visualization tool to reveal the pore geometry of sandstone reservoirs and determine the distribution of gases within such reservoirs. Our study can serve as a foundation for understanding the behavior of gases in subsurface reservoirs, improving oil and gas prospecting and exploration, and assessing CO₂ storage.

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