Assessment of a mature hydrocarbon field in SE Czech Republic for a CO2 storage pilot

Abstract

Preparation and execution of a CO2 storage pilot project is one of the first logical steps in the effort to kick-start CCS in the region of Central & Eastern Europe, utilizing onshore geological structures for permanent CO2 storage. The main aims of this activity are to test the suitability of local geological structures and demonstrate the feasibility and safety of the technology to local stakeholders. The Czech-Norwegian CO2-SPICER project is an example of such developments. The target structure of CO2-SPICER – Zar−3 – is a hydrocarbon field situated in an erosional relict of fractured carbonates of Jurassic age on the SE slopes of the Bohemian Massif, covered by Paleogene deposits and Carpathian flysch nappes. The first stage of site assessment has been completed, and the article provides an overview of its results. Construction of a 3D geological model of the storage complex was the first important step on the route, preparing input for subsequent reservoir simulations of the field history and planned CO2 injection. Reservoir assessment is also focusing on specific features of the fractured-vuggy reservoir and accounting for the effects associated with CO2 injection, including geochemistry and geomechanics. Geochemical studies focus on fluid-rock interactions, and geomechanical ones on formation integrity and fracture mechanics under reservoir pressure build-up and cooling of the formation by injected CO2. Risk assessment is another component of the project, aiming at identifying potential leakage pathways and assessing consequences for the area of interest. Preparatory work for the site monitoring plan includes applicability analysis of various monitoring methods, supported by execution of baseline monitoring of selected phenomena, in particular composition of soil gas, natural and induced seismicity and properties of shallow groundwater. The project also includes evaluation of advanced reservoir containment monitoring technologies including time-lapse pressure transient analysis. While the key actions are directed towards the piloting activities, the project also looks beyond to full-field implementation and potential to establish a regional CCS cluster.