Rock core-based pre-stress evaluation experimental validation: A case study on Yutengping Sandstone as CO2 storage reservoir rock

摘要

Yutengping Sandstone in Tieh-chan-shan, Taiwan is a potential reservoir for geological CO2 storage. Cyclic loadings were applied to rock samples taken from an outcrop to create artificial pre-stress. The pre-stress evaluation accuracies using two core-based techniques, acoustic emission (AE) and deformation rate analysis (DRA), were investigated under different pre-stresses, delay times and curing temperatures. The experimental results validate the pre-stress evaluations using AE and DRA. The delay time and curing temperature were shown to have minor impacts on the measurement accuracy. However, although both axial strain and lateral strain can be used in DRA, the stress memory fades as the delay time increases. Therefore, delay time, which represents the time from the borehole drilling to the DRA test, must be carefully considered when applying these techniques to evaluate the in situ stress of Yutengping sandstone.