Using legacy data from the oil industry to evaluate volcanic formations for geological CO2 storage: A case study from the Campos Basin, Brazil

Abstract

Geological CO₂ Storage (GCS) in basaltic/volcanic formations is a promising avenue for mitigating anthropogenic emissions of greenhouse gases because these regions can effectively trap CO₂ via mineralization. However, implementing CO₂ storage projects in offshore regions demands significant investment due to the requirement to explore vast areas as well as characterize any potential prospects to verify their technical and economic feasibility. Legacy data from the oil industry could be used to provide an initial assessment of potential prospects in sedimentary basins with volcanic formations. In this study, we demonstrate the immense value of legacy products, including seismic and well log data, to identify zones with higher potential for CO₂ storage. This study investigates the unconventional, mature volcanic oil reservoir of the Cabiúnas Formation in the Badejo Field, Campos Basin, Brazil, because the flood basalts that formed these reservoirs represent candidates for GCS projects in shallow water domains. Understanding the mechanism of hydrocarbon migration and accumulation in these reservoirs will provide insights into the factors that control fluid flow in basaltic rocks, helping eventual future investigation focusing CO₂ storage. This investigation employed tools commonly used by the industry for exploratory investigations and reservoir characterization, based on seismic data interpretation and attribute analysis. We also performed porosity distribution estimation with an acoustic impedance inversion method based on a neural network plugin. The legacy data allowed us to characterize the complex relationships between fractures and aspects such as paleo-topography and the control of fault zones on lateral flow. We find that the relationship between faults/fractures and the apparent porosity of the volcanic succession is critical for predicting the reservoir response to CO₂ injection. Legacy data from the oil industry that covers offshore regions that contain volcanic successions thus represents a valuable resource that can help save costs and accelerate the development of GCS projects.