A preliminary evaluation of the CO2 storage capacity of the Italian geological reservoirs based on the interpretation of deep well data.

Abstract

A preliminary study of the CO2 storage potential of Italian geological reservoirs based on the interpretation of deep well data

F.Moia, E.Rondena, G.Locatelli -CESI RICERCA SpA- Milano F.Quattrocchi, M.Buttinelli, B.Cantucci, M. Procesi (*) – INGV Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 1, (*) now PhD Roma tre University

Abstract

Several technological options have been proposed to stabilize and reduce the atmospheric concentrations of carbon dioxide (CO2) among which, the most promising for Zero Emission Fossil Fuel Power Plants (ZEFFPP European Platform), are the CCS technologies (Carbon Capture and Storage). The remedy proposed for large stationary CO2 sources as thermoelectric power plants is to separate the flue gas capturing CO2 and to store it into deep subsurface geological formations (more than 800 meters of depth). In order to support the identification of potential CO2 storage reservoirs in Italy, a detailed reworking of available geological, geophysical, geochemical and seismological data is under development by our partnership, in the framework of the project “Identification of Italian CO2 geological storage sites”. This research started from the study of the 7575 wells drilled on Italian territory during the last 50 years for gas/oil and geothermal exploration. Among the data-set as a whole, a selection of 1688 wells deeper than 800 m was accomplished. Only 1290 of these wells have a public-available stratigraphy and fit with the basic prerequisites for further deepening of their CO2 reservoir potential, mostly as saline aquifers. The wells data have been extracted and organized into a geological data base, that contains information about the nature and the thickness of geological formations, the presence of fresh, saline or brackish water, brine, gas and oil, the underground temperature, the seismic velocity and electric resistance of geological materials from different logs, the permeability, porosity and geochemical characteristics. The most important parameter to be considered to classify the selected wells into different “caprock quality” classes, is the caprock thickness and lithology (alias permeability), covering the saline aquifer/s. To quantify the quality of the caprock of a single well, we clustered 5 different classes of “Impervious Factor Reliability” (Fbp= Fattore Bontà Pozzo, in italian), function of the estimated permeability. A second variable has been assigned to each well named “Aquifers Availability”, sub-divided in 5 “trapping factor reliability” as a preliminary sum of all the parameters considered.