Subsurface Geology of the Paraná-Etendeka Large Igneous Province: Implications to Province Stratigraphy and CO2 Storage

Abstract

Volcanic reservoirs represent an important target for CO₂ storage and large-scale deployment. We accessed the volcanic stratigraphy of the Paraná-Etendeka Large Igneous Province (PELIP) in South America through the analysis of petrophysical data from 9 exploration wells and regional seismic data. This approach enables the development of a refined geological model of the subsurface, offering new insights into facies distribution and reservoir characteristics. Stratigraphically, the PELIP consists of two major volcanic sequences: an older low-Ti (LT) sequence in the southern region and a younger high-Ti (HT) sequence in the central-northern area. Seven distinct lava formations have been identified based on their architecture and geochemical signatures, with the Vale do Sol, Pitanga and Paranapanema formations accounting for over 80% of the stratigraphy. The province is formed by thick (c. 25 m) tabular lavas with well-developed vesicular and brecciated upper crusts and subordinately compound lavas and volcaniclastic/siliciclastic deposits. Petrophysical analyses reveal a strong correlation between rock facies and reservoir properties (i.e., porosity and permeability). Lava flow tops exhibit high porosities comprising c. 10%–40% of the total flow thickness and represent viable targets for CO₂ injection. In contrast, massive flow cores are low in porosity and may act as effective seals. The PELIP is geologically similar to other large igneous provinces currently hosting CCS (carbon capture and storage) projects (Carbfix, Iceland and Wallula, USA). The large volume of basaltic rocks, along with high porosity facies and reactive compositions, makes the Paraná-Etendeka LIP a potential target for CCS developments in South America.