CO2 storage algorithms involving the hybrid geological reservoir of the Irati Formation, Parana Basin

Abstract

The injection and permanent storage of carbon dioxide (CO2) in depleted hydrocarbon reservoirs is a norm in atmospheric CO2 reduction practices. Currently, in the Irati Formation, there are no hydrocarbon production events; therefore, this study applies detailed petrophysical and seismic evaluations to present the algorithms for predicting CO2 storage potentials of the shale and carbonate reservoirs. There are studies involving the overview of the CO2 storage potential of the study location; however, an exhaustive presentation such as this is novel in the region. It proposes the shale-carbonate hybrid geological reservoir to maximise the storage capacity by reducing the geological constraints associated with thin-bedded layers, inadequate overburdens, water saturation (Sw), fault distributions, total organic content (TOC), and porosity (Ф). It reveals that the geological and other carbon capture and storage (CCS) related parameters presented for the conceived hybrid reservoir conform to the CO2 storage criteria considering the research results and existing atlases. The study shows average values for Ф (8.2% in shale and 13.1% in carbonates), TOC (8.8% in shale and 5.6% in carbonate) and reservoir thickness (13.7 m for shale and 15.4 m for carbonate) involving an estimated area of 4.3 × 109 m2. It presents an average value of 13.0% for Sw at depths ≥950 m, and the estimated CO2 storage capacity of the hybrid geological reservoir is 13.58 Gt. Therefore, the results of this study will assist in making an informed decision concerning the actualisation of CO2 storage within the Irati Formation and related geological units, especially in the absence of pre-determined data from hydrocarbon production.