Time-lapse Seismic Data Inversion for CO2 Sequestration CO2CRC Otway Project

The second stage of the CO2CRC Otway Project aims to explore the capabilities of various technologies - including time-lapse seismic - for the monitoring of small amounts of supercritical CO2/CH4 mixture. To this end, 15 kt of CO2/CH4 mixture was injected at the depth of 1.5 km into the saline sandstone reservoir in 2015–2016. A part of the monitoring program completed to date consists of a baseline survey followed by three monitor surveys after the injection of 5 kt, 10 kt and 15kt. Time-lapse seismic paired with simultaneous 4D inversion is a proven tool in reservoir monitoring because of its effectiveness in tracking the movement of CO2 and providing quantitative estimation of the changes in reservoir acoustic impedances. Here we demonstrate our workflow and the results of post stack model-based 4D seismic data inversion. The workflow was first tested and calibrated on the 4D synthetic time-lapse data. The calibrated workflow was then applied to the field seismic data.