Photoacoustic microscopy of sandstone reservoirs rocks

The porosity of materials is an important parameter in several areas, ranging from industry to biomedicine. For sandstone rocks, the mineral composition is interesting in the oil industry and could be related to porosity and permeability. For example, the amount of rigid grains, such as quartz and feldspar, in sandstone composition can support the overload pressure, preserving the primary pores. Furthermore, the amount of feldspar could be positively correlated with porosity. On the other hand, mixtures of illite/smectite could reduce porosity. With the goal to investigate alternative techniques to analyze porous media, this work studies the application of photoacoustic microscopy in sandstone rocks. Photoacoustic microscopy is based on the photoacoustic effect, converting optical absorption into acoustic waves, and carrying both mechanical and optical information of the sample. Thus, the difference in optical absorption among the different minerals in sandstones could act as a contrast agent in the photoacoustic signal, allowing differentiation. Photoacoustic microscopy images were acquired in eleven sandstone rock samples to evaluate the intensity and frequency of the photoacoustic signal. The signal intensity was compared with photographs to analyze the mineral composition, and the signal frequency was used in morphology analysis. © 2023 IEEE.