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

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.acceptedVersio

Inquiry into the temperature changes of rock massif used in energy production in relation to season

This research was undertaken to perform and evaluate the temperature measurement in the ground utilized as an energy source with the goal to determine whether significant temperature variations occur in the subsurface during the heating season. The research infrastructure situated on our University campus was used to assess any variations. The observations were made at the so called "Small Research Polygon " that consists of 8 monitoring boreholes (Borehole Heat Exchangers) situated around a borehole used as an energy source. During the heating season, a series of monthly measurements are made in the monitoring boreholes using a distributed temperature system (DTS). Raman back-scattered light is analysed using Optical Frequency Time Domain Reflectometry (OTDR). Our results indicate that no noticeable changes in temperature occur during the heating season. We have observed an influence of long-term variations of the atmospheric conditions up to the depth of a conventional BHE (& AP;100 m). The resulting uncertainty in related design input parameters (ground thermal conductivity) was evaluated by using a heat production simulation. Production data during one heating season at our research facilities were evaluated against the design of the system. It is possible to construct smaller geothermal installations with appropriate BHE design that will have a minimal impact on the temperature of the surrounding rock mass and the system performance.Web of Science2121art. no. 702