The effect of temperature on 3D rock structure of andesite rock sample from potential geothermal area, Sulawesi-Indonesia

Abstract

Abstract An andesite rock sample was taken from potential geothermal area on Lili-Sepporaki, west Sulawesi. The sample is an impermeable cap rock with a high silica mineral at alteration zone around a manifestation. Its Three-dimensional rock structure was analyzed to see its deformation due to temperature change. Change of temperature from 24˚C to 100˚C, 150˚C, 200˚C, and 250˚C was applied to the sample. Subsequent to each change of temperature, the sample was scanned using a micro-Computed Tomography Scan (μ-CT Scan). From the scanning process, a sub-volume 300 pixels were reconstructed, and its 3D pore and mineral structure were characterized. It is found that porosity {φ (T)}, specific surface area {SsA (T)} decrease polynomial for pore structure and increase polynomial as temperature increases. This result show that as temperature increases the volume of mineral is bigger make the pore volume smaller. The Fractal dimension for pore structure (2.65 ± 0.02) and for mineral structure (2.89 ± 0.015).