Monitoring techniques developed at CO2 natural laboratories to improve risks assessment and safety strategy

Transcription

1 Monitoring techniques developed at CO2 natural laboratories to improve risks assessment and safety strategy Sabina Bigi Dipartimento di Scienze della Terra Sapienza Università di Roma 3 rd International Workshop «Promoting CCS in», March Craiova, 1

2 Fluid Chemistry Laboratory Earth Science Department University of Rome La Sapienza Salvatore Lombardi Stan Beaubien Stefano Graziani Aldo Annunziatellis Annalisa Alemanni 3 rd International Workshop «Promoting CCS in», March Craiova,

3 Summary Introduction Example of monitoring techniques at Natural Laboratory in Italy Offshore and Onshore Modality of CO2 Migration through Faults and Fractures Conclusion 3 rd International Workshop «Promoting CCS in», March Craiova,

4 Introduction Carbon capture and storage (CCS) has been shown to be a realistic and safe approach to rapidly decrease manmade greenhouse gas emissions Weyburn Sleipner In Salah However a lack of public support, due to concerns over risks, could potentially stop the wide-spread implementation of this promising technology 3 rd International Workshop «Promoting CCS in», March Craiova,

5 People should know that : Introduction scientific knowledge exists to select the best and safest sites, techniques and approaches exist to monitor the safety of these sites during operation and post-injection; and technologies exist if it is necessary to remediate a leak. In other words, that all potential risks have been examined and minimised. One of the principle concerns is CO 2 migration towards the surface and its potential leakage to the atmosphere The study of these NATURAL LABORATORIES, where the release of deep gases occurs naturally can be used to help us: to understand gas migration mechanisms in real geological systems in terms of scale, long time periods, structure, complexity, etc. over a range of flow rates and thus to help suggest criteria to assess risk and define safety standard 3 rd International Workshop «Promoting CCS in», March Craiova,

6 Introduction These types of sites are particularly common in Italy, due to its active tectonics and high seismicity Seismic risk in Europe Risk Management Solutions, Inc. (2008) gas accumulations have been found in all different geological settings some of which are well sealed (CH 4 or CO 2 reservoirs) others leak varying amounts of deep-origin CO 2, CH 4, or He to the atmosphere (e.g. geothermal areas). 3 rd International Workshop «Promoting CCS in», March Craiova,

7 Introduction Gas migration has been studied by our group for more than 25 years using experiments and soil gas surveys (>40,000 samples) Green areas represent soil gas surveys performed above gas reservoirs in all different geological settings Red dots indicate areas with significant CO2 emanations Adriatic Sea Total area covered by CO 2 soil gas surveys 5800 km 2 Area with CO 2 > 20% (v/v) 0.85 km 2 (0.01%) Area with CO 2 > 10% (v/v) 3.3 km 2 (0.06%) Tyrrhenian Sea Surveyed areas. CO2 emanations (soil gas samples collected at 80cm depth) 3 rd International Workshop «Promoting CCS in», March Craiova,

8 CO2 leaking sites The Latera Caldera geothermal area with localised macroleakage visible impact The Vasto area natural gas field with diffuse microleakage only found with sensitive geochemical instruments The Panarea island Underwater Geothermal area macro and microleakage Submarine impact simplified geological map of Italy showing the location of the major CO2 point sources Bertello et al., rd International Workshop «Promoting CCS in», March Craiova,

9 The Latera Caldera CO2 production by thermo-metamorphic processes Gas seeps (95% CO 2 ) occur throughout the valley Gas migration along fault - Emissions localized in vents and distributed along faults Just one tectonic phase The high flux seeps are visible on surface due to their impact on vegetation, while low flux seeps are not visible 3 rd International Workshop «Promoting CCS in», March Craiova,

10 In the Latera Caldera field Lab is possible to observe and measure the fault-controlled gas migration process directly in the field. Integration of different field data at different scale Build a migration model Soil gas surveys at regional and local scale Structural geology (field data) Conceptual migration model Modeling fracture network (Autocad and Petrel) Fluid flow simulation (Comsol Multiphysics) October 17-19, 3 rd International 2011 Workshop «Promoting CCS in 2 nd CGS», March Europe Knowledge 2012 Sharing Craiova, Workshop Maria Laach, Germany Natural Analogues

11 Latera regional CO 2 leakage Local N-S trends Regional SW-NE trend Even in this area with continual CO 2 production and faults, the total leakage area is small: Total area covered by CO 2 soil gas surveys (soil gas samples collected at 80cm depth) 50 km 2 Area with CO 2 > 20% (v/v) 0.01 km 2 (0.02%) Area with CO 2 > 10% (v/v) 0.08 km 2 (0.16%) 3 rd International Workshop «Promoting CCS in», March Craiova,

12 Latera percentage of leakage site CO2 flux (g/d) locations account for 97.5% of CO 2 flux total rd International Workshop «Promoting CCS in», March Craiova,

13 Main fault systems at regional and local scale Two main different fault zone architectures internal geometry of the fault zone different permeability distribution 3 rd International Workshop «Promoting CCS in», March Craiova,

14 An high permeability fault network Feldspar and Kaoline quarry-latera caldera Conjugate normal fault systems Well developed damage zone Homogenous Fracture Spacing and density Repeated every 5-10m in the quarry extensional fractures normal fault conjugate fault system dip-slip normal faults 3 rd International Workshop «Promoting CCS in», March Craiova,

15 A well developed fault core (low permeability) Feldspar and Kaoline quarry-latera caldera 3 rd International Workshop «Promoting CCS in», March Craiova,

16 A well developed fault core (low permeability) 1000 g/m 2 day CO2 flux rd International Workshop «Promoting CCS in», March Craiova,

17 The conceptual model Fault zone permeability evolution Fracture network fault Well developed fault core Annunziatellis et al., 2008 Faults can develop both these architectures as a function of competition of strain localization vs. strain distribution in time and in space along the fault trace 3 rd International Workshop «Promoting CCS in», March Craiova,

18 CO2 flux (g m-2 d-1) Latera leakage pathways CO 2 flux - leakage only at permeable points along faults m 3 rd International Workshop «Promoting CCS in», March Craiova,

19 Main faults and CO2 leakage distribution along strike 3 rd International Workshop «Promoting CCS in», March Craiova,

20 Vasto The Vasto Basin is a wide area (of about 2000 km 2 ) located in the Adriatic Foredeep (central Italy) The basin, filled by about 2500 m of Plio- Pleistocene marine sediments, is characterized by both extensive and compressive buried tectonics which facilitated the formation of hydrocarbon traps. Geological, geomorphological, structural and geochemical studies have been carried out to study gas migration along brittle deformation masked by sandstones and clays sedimentary cover Apennines frontal thrust 3 rd International Workshop «Promoting CCS in», March Craiova,

21 Vasto Contour map of CO2 concentrations (Regional sampling) 3 rd International Workshop «Promoting CCS in», March Craiova,

22 Tectonic lineaments and gas correlation Vasto area, periadriatic basin VASTO Top of Apulia Platform isochrones map VASTO (1987/88) contour map of He concentration (Regional sampling) VASTO (2004/05) contour map of He concentration (Regional sampling) 3 rd International Workshop «Promoting CCS in», March Craiova,

23 Eolian archipelago Panarea island Volcanic island with six periods of explosive and effusive activity (last emission activity years). Outcrop of a large volcanic apparatus that rises from the surrounding seabed (1.000 meters deep). Presence of faults along local and regional alignments (NW-SE, NE-SW). Strong hydrothermal/volcanic submarine gas vent system. Gas vents aligned mainly along the tectonic features. 3 rd International Workshop «Promoting CCS in», March Craiova,

24 Panarea gas permeable structures Esposito et al. (2006) bubbles underwater fractures Mapped lineaments (left) and measured fracture orientations (right). Principle direction is SW-NE, in agreement with regional Panarea-Stromboli direction. 3 rd International Workshop «Promoting CCS in», March Craiova,

25 3 rd International Workshop «Promoting CCS in», March Craiova,

26 Continuous measurements A continuous monitoring station was installed by URS, with a central control station on land linked by cable to 6 underwater pco2 probes. Station transmits in real-time to internet server 3 rd International Workshop «Promoting CCS in», March Craiova,

27 Continuous measurements Each probe has two CO2 sensors with different measurement ranges (0-5%, 0-100%) Probes deployed at background, moderate flux, and high flux areas. October 17-19, 3 rd International 2011 Workshop «Promoting CCS in 2 nd CGS», March Europe Knowledge 2012 Sharing Craiova, Workshop Maria Laach, Germany Natural Analogues

28 Continuous measurements Two sensors in one probe give good correlation Temporal variability of system is clearly seen Probes deployed 10 m apart at the moderate flux site show the same events Large difference in response between the probes at the seep and background sites Correlation with other kind of events 3 rd International Workshop «Promoting CCS in», March Craiova,

29 Conclusions The study of natural analogues, like the two that I have described here, help us understand the migration mechanisms, pathways, and geological controls that influence the potential for CO2 leakage. This knowledge gives us a powerful tool to make CCS as safe as possible, because it establishes criteria that can be used for risk assessment and safety strategy Site assessment methods developed at natural laboratories are used to show if there are any potential migration pathways at a site considered for CO2 storage - ie what is the potential risk at this site? Monitoring knowing where and how CO2 might leak helps us define a safety strategy, both by focusing work on highest risk areas and for planning any eventual remediation plan 3 rd International Workshop «Promoting CCS in», March Craiova,

30 Thank you for your attention 3 rd International Workshop «Promoting CCS in», March Craiova,