Well materials ageing in H_2S-CO_2 environment at high pressure and high temperature - experiments and modelling

摘要

The ageing of deep well construction materials (cement and steel) analogues has been investigated by laboratory experiments under 500 bar-120°C and 500 bar-200°C in an H_2S-CO_2 environment. New experimental and analysis procedures were designed for this study. The materials have been aged within three fluids: 1) a brine with dissolved H_2S-CO_2; 2) a biphasic fluid; 3) a dry supercritical H_2S-CO_2 phase. Different carbonation features were observed according to the three exposures conditions. The cement carbonation was maximal when occuring within the dry supercritical phase (without liquid water) for the proposed experimental procedure. A numerical reactive transport model was designed with HYTEC to reproduce the front observed after ageing in brine with dissolved H_2S-CO_2. The results confirmed the ageing processes evidenced by the experiments. The results of this study could be used for further numerical models calibration required for upscaling; Nevertheless, the validity of such upscaling of the results in a well configuration will require further assessment and studies.