DAS-VSP Application to Monitor CO2 Injection Within a Carbonate Saline Aquifer Onshore UAE: A Quantitative Approach

This paper presents the quantitative seismic interpretation aspect of a multidisciplinary study, focusing on the integration of rock physics modelling from well logs with repeated Zero-Offset VSP measurements for monitoring CO2 injection using DAS VSP on a carbonate saline aquifer onshore Abu Dhabi. A complete analysis of the comparison of the monthly recorded ZOVSP before and during CO2 injection is presented. An increase in time delay at the top of a large reflective layer is observed gradually once CO2 injection has started, with an associated change of amplitude. The base and monitor references are then inverted, highlighting a decrease in acoustic impedance with time at the top of the perforation zone, in magnitude comparable to those predicted by the modelling. This quantitative interpretation study based on ZOVSP analysis validates the likelihood of detecting acoustic impedance variations associated with CO2 injection using seismic data in a carbonate saline aquifer. This opens the gate to a similar quantitative analysis to be performed on the 3D DAS-VSP data to monitor spatial changes away from the well provided velocity models are updated accordingly during the processing stage.