Experimental study on observation of critical behaiviors and critical points of geofluids by using spectroscopic measurement

Abstract

Spectroscopic measurements in the range from 350 nm to 1050 nm for pure H₂O, CO₂ and C₂H₅OH fluids under high temperatures and pressures were carried out to observe critical phenomena by using visible-type autoclave. Intensity of transmitted light though the fluid became low drastically around the critical point in both cases of H₂O and C₂H₅OH. Intensity of transmitted light through CO₂ was very low under subcritical condition and was high in supercritical region. Differences between experimentally determined critical temperature and reference data in literature of pure fluids were within ca. 1.6°C, and pressure differences were less than 0.3 MPa.