Effect of residual oil saturation on CO2 injectivity-A case study from Nini West Depleted Oil Field

To contribute to global warming by reducing the greenhouse gases in the atmosphere, CO2 needs to be stored after capturing. Different examinations should be conducted on the reservoir material to ensure safe storage of CO2 in the geological infrastructure, such as reservoir capacity estimation, injectivity, and fluid-rock interactions. Depleted oil fields are among the options for storage, as well as saline aquifers. Injectivity of Nini West Depleted Oil Field situated in Siri Canyon is evaluated in the current study. For this purpose, the sandstone reservoir samples have been restored to the same condition as in the oil leg of the depleted field by establishing the initial water saturation, ensuring the ageing time of one month for wettability restoration, followed by water flooding to reach irreducible oil saturation in the samples. After water flooding the samples with Nini synthetic brine, supercritical CO2 was injected at reservoir conditions of 60 °C and 200 bara pressure. Supercritical CO2 was injected through the samples in a cyclic injection manner to mimic the operational condition for storing the CO2 in the subsurface by transporting the CO2 by ship. This way of transport results in intermittent injection of supercritical CO2 instead of continuous.