Time-Lapse FWI Using Borehole Seismic Data for CO2-EOR Monitoring in a Carbonate Field Onshore Abu Dhabi

Abstract

Abstract Time-lapse seismic plays a vital role in monitoring the dynamic behavior of reservoirs during carbon dioxide enhanced oil recovery (CO2-EOR). However, its application to carbonate fields onshore Abu Dhabi presents several challenges, necessitating appropriate datasets and analysis tools. For proper understanding of fluid behaviors in a carbonate field onshore Abu Dhabi, the time-lapse vertical seismic profiling (VSP) datasets were acquired with an optimum signal-to-noise ratio. Firstly, pre-processing was performed on baseline and monitoring surveys, resulting in improvement of data quality and repeatability in a quantitative manner. We then applied full waveform inversion (FWI) to estimate time-lapse velocity changes induced by CO2-EOR. After the parameter optimization, the inverted velocity showed updates in the correct direction while minimizing the data residual. To stabilize and optimize the time-lapse FWI application, three different approaches were performed: a parallel approach, a common model approach, and a target-oriented approach. As a result, the time-lapse velocity changes near the injection well were clearly recognizable in the reservoir of interest. This has suggested that time-lapse property changes associated with CO2-EOR operation can be captured through time-lapse FWI. Therefore, time-lapse borehole seismic imaging in conjunction with the applied FWI scheme can be an effective tool for precise monitoring of fluid behavior in a carbonate reservoir during CO2-EOR operations.