DEVELOPMENT OF AN ITALIAN CATALOGUE OF POTENTIAL CO 2 STORAGE SITES: an approach from deep wells data DEVELOPMENT OF AN ITALIAN CATALOGUE OF POTENTIAL CO 2 STORAGE SITES: an approach from deep wells data Quattrocchi F. (1), Buttinelli M. (1,2) , Procesi M. (2), Cantucci B. (1), Moia F. (3) contacts: quattrocchi@ingv.it, barbara.cantucci@ingv.it; mauro.buttinelli@ingv.it; mprocesi@uniroma3.it; fabio.moia@cesiricerca.it (3) CESI RICERCA S.p.A., Via R. Rubattino 54, 20134 Milano, Italy (2) Università degli studi Roma3, Geological Science Department, L.go S. L. Murialdo 1, 00146 Rome, Italy (1) INGV, Department of Seismology and Tectonophysics, UF Fluids Geochemistry, Geological Storage & Geothermics, Via di Vigna Murata 605, 00143 Rome, Italy European Geosciences Union General Assembly 2008 Vienna, Austria, 13 – 18 April European Geosciences Union General Assembly 2008 Vienna, Austria, 13 – 18 April This research started from the analysis of the 7575 wells drilled on Italian ter- ritory during the last 50 years for gas/oil exploration. A sub-dataset of 1291 wells (deeper than 800 m) have been selected. The evaluation of the caprock and aquifer/s presence and quality has been done on these selected wells. wells with depth greater than 800m WORKING DATA Stabilize and reduce the atmospheric concen- tration of anthropogenic greenhouse gases is one of the principal goal that have to be accom- plished in short time, in order to reduce the cli- mate changes and the global warming, follow- ing the World Energy Outlook 2007 program by IEA. The most promising remedy, proposed for large CO 2 sources like thermoelectric power plants, refineries and cement industries, is to separate the flue gas capturing the CO 2 and to store it into deep sub-surface geological reservoirs, such as deep saline aquifers, depleted oil and gas fields and unminable coal beds. Among these options, deep saline aquifers are consid- ered the reservoirs with the larger storage po- tentiality (about 10 4 GtC), as a consequence of a wide availability with respect to deep coal seems, depleted oil fields and gas reservoirs. EUROPE OVERVIEW ON GEOLOGICAL STORAGE OF CO 2 ITALY DISTRIBUTION OF SEISMICITY The identification of a possible site of CO 2 injection necessarily must consider the distance from seismogenetic structures, preferably in a low seimicity area. INGV - “ISIDE” SEISMIC EVENT CATALOGUE April 2005 - March 2008 Best caprock situations Fbp INGV DISS 3.0.2.2 (Database of Individual Seismogenetic Sources) Seismogenetic areas - events with M>5.5 sources from hystorical earthquakes sources from geological/geophysical data sources from hystorical seismicity sources from hystorical earthquakes number of observations Magnitude sub-dataset of 45774 events registered from 01/01/1981 to 03/03/2008. 88,4% have a low magnitude between 1,5 and 3. some statistics on italian seismicity (January 1981-March 2008) number of observations ipocentral depth (km) costs/benefits of CO 2 injection (between 800 and 2500m of depth): - LOW SEISMICITY - 97906 registeres events 5,6% between 1 and 3 km depth=0 is a database NO-DATA The identification of a possible storage site necessarily passes through the demonstration that CO 2 can be injected in ex- tremely safe conditions (T=38°C and P=78 atm, under the criti- cal point of CO 2 ). It is also necessary to consider some geological\economical factors as: Aim of this work is to establish some site selection criteria to demonstrate the pos- sibility of the geological storage of CO 2 in Italy, even if It is located in an active geo- dynamical domain. - impermeable caprock - aquifer/s presence - seismicity - Diffuse degassing structures - Heat Flow - costs/befits of injection - distance from power plants (CO 2 transport costs) Caprock classification Fb p - count 1 A classification based on the permeability of the lithologies encountered during drilling processes has been done. We cluster the lithotypes in 5 classes (Cl i ). Cl i =1 belong to per- meable lithologies. Cl i =5 to impermeable lithologies Lithotype Permeability Cl i class Conglomerates, gravels and alluvial deposits Very high 1 Sandstones, Limestones, intrusive rocks, metamorphic rocks High 2 Marls and flyschoid sediments (clayish sandstones) Medium 3 Clayish marls, Sandy clays, Schistose clays Low 4 Clays, Chalky Clays, Evaporitic rocks Very Low 5 2 3 Using the classification of the lithologies by the Fb i param- eter (Lithotype quality factor), also the thickness of a lithotype (Sp i ) has been considered, with respect to an ideal thickness of impermeable lithology (Sp c ) fixed to 800m c i i i Sp Sp Cl Fb ⋅ = Wells analysis show that many lithologies contribute to the efficiency of the caprock. A single analysis of each caprock situation has been accomplished to define the Fb p factor (CAPROCK QUALITY FACTOR) CAPROCK QUALITY DEFINITION Description Permeability Caprock efficiency Fb p Caprock absence with/or superficial aquifer Maximum Absent 0 que caprock lithology or lithotype series with predominant Fb i =1 Very high Very low 1 que caprock lithology or lithotype series with predominant Fb i =2 High Low 2 que caprock lithology or lithotype series with predominant Fb i =3 Medium Medium 3 ique caprock lithology or lithotype series with predominant Fb i =4 Lithotype with Cl i =4 and Sp i >400m setted at a depth >800m Low High 4 ique caprock lithology or lithotype series with predominant Fb i =5 - Lithotype with Cl i =5 and Sp i >400m setted at a depth >800m Very Low (Maximum security) Very high 5 Fb p distribution (caprock quality) on the Italian territory Best caprock situations Fbp ON 1291 ANALYSED WELLS, 421 HAVE A GOOD OR OPTIMAL CAPROCK QUALITY (Fb P = 4-5) Uni Uni Uniq Uniq Uniq - The identification of a possibile site of injection must consider the relative dis- tance from the DDS (Diffuse Degassing Structures - areas with high fracturing, where exist preferential pathways for rising fluids (as natural as injected CO 2 ) and the relative closeness to anthropogenic CO 2 sources(transport costs) DISTRIBUTION OF DDS AND ANTHROPOGENIC CO 2 EMISSIONS Power Plants CO2 emissions (kton/year) Anthropogenic CO2 sources CO2 emissions (kton/year) Best caprock situations Fbp Best caprock situations Fbp DDS (Diffuse Degassing Structures) Final aim is to apply this model to real CO 2 storage feasibility studies in Italy , in areas with appropriate cap-rock nature, thickness, and quality of deep aquifer/s. In these cases it is necessary to implement the knowledge by: i) better evaluation of saline aquifer quality; ii) estimation of CO 2 storage ca- pacity by 3D-modeling of deep crustal structures; iii) fluid-dynamic and geo- chemical modelling of water-rock-CO 2 interaction paths. CONCLUSIONS DISTRIBUTION OF DEEP AQUIFERS it has been created a geodatabase on the nature and quality of deep aquifers for the high-ranking wells sub-dataset (Fb p = 4-5, where aquifers data are available), contain- ing the following parameters: i) presence of one or more aquifers deeper than 800 meters; ii) thickness of the aquifer/s; iii) lithology of the reservoir/s; iv) available chemical analysis; v) distance from closer power plants or other anthropogenic CO 2 sources. aquifers distribution with depth >800m symbol - count some statistics on italian deep aquifers 199 wells have informations about aquifer/s. 58% have at least one aquifer 62% of the aquifers is “easily” accessible (top setted between 800 and 1800m) number of aquifers setted at depth >800m ONLY 199 well logs report informations about a deep aquifer 63% of aquifers are hosted in sands and limestones Approximately 50% of the aquifers have a thickness between 75 and 400 m distribution of the depth of the top af acquifers ON 421 WELLS WITH Fb P = 4-5, APPROXIMATIVELY 30% HAVE POTENTIAL AQUIFERS SUITABLE TO CO 2 STORAGE distribution of aquifers-lithologies distribution of thickness of the aquifers thickness (m) sandstones claystones Clays and M ar ls Clays and sands Gravels M ar ly limest ones Arenaceous Limest ones Limest ones B reccias M ar ls Sands number of observations number of observations number of observations number of observations top of the aquifer (depth - m)