Containment and. Pathways. Containment & Pathways. Cap Rocks. Unwanted Leakage. Franz May. IEA GHG Summer School 2011

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Storage Complex Overburden Containment and

GHG Summer School 2011 Cap rock Faults Spill

reservoir Unwanted Leakage Avoiding leakage of :

reservoir fluids (oil, salt water) Cap Rocks

environment www.n24.de/news/newsitem_5301544.

1 Storage Complex Overburden Containment and Containment & Pathways Pathways Franz May IEA GHG Summer School 2011 Cap rock Faults Spill points Overburden Wells reserve aquifer cap rock reservoir Unwanted Leakage Avoiding leakage of : - CO 2 - impurities (corrosive, toxic) - reservoir fluids (oil, salt water) Cap Rocks rock salt Protection of: - human health - atmosphere - potable water aquifers - underground mines and resources - and environment Nuclear waste repository, Asse, Germany Natural gas storage in salt caverns in North Germany 1

Cap Rocks anhydrite, gypsum, clay Cap Rocks (marl, limestone) Egyptian

Switzerland Open pit clay mining, near Eger, Czech Republic Cap Rocks

negligible when well logging and testing, core analysis and seismic

$high capillary entry and frac pressure, suitable mineralogy) coherent$ surroundings greater than seismic resolution acoustic facies contrast to

surroundings greater than seismic resolution acoustic facies contrast to

2 Cap Rocks anhydrite, gypsum, clay Cap Rocks (marl, limestone) Egyptian vase, gypsum anhydrite cap rock, drill core, Altmark natural gas field, Germany Mt. Terri underground test site for radioactive waste deposition, Switzerland Open pit clay mining, near Eger, Czech Republic Cap Rocks argillite, slate: water proof, lasting Tight Cap Rocks Leakage should be negligible when well logging and testing, core analysis and seismic exploration proof: good seal quality (low porosity and permeability, high capillary entry and frac pressure, suitable mineralogy) coherent distribution sufficient thickness distinctive properties storage area & surroundings greater than seismic resolution acoustic facies contrast to adjacent strata natural CO 2 reservoir underneath of villages in Central Germany Foto Öchsen Landschaft slate roofs of medieval houses in Bernkastel, Germany) 2

3 Leakage through Cap Rocks sandy aquifer Chemical Alteration of Cap Rocks dissolution and re-crystalization in rock salt (NaCl) Carnallite KMgCl 3. 6H 2 O Sylvinite KCl clay cap rock CO 2 vent in a clay mine near Eger, Czech Republik 40 cm Merkers, potassium mine, Thuringia, Germany Chemical Alteration of Cap Rocks Chemical Alteration of Cap Rocks Chlorite Kaolinite + Siderite or Goethite + Quartz Kaolinite 0.01 mm 0.1 mm REM image of shale sample from a CO 2 production well in Wehr, Germany un-altered slate compared to chlorite bearing silt stone from a CO 2 production well 3

Chemical Alteration of Cap Rocks Faults NE Otway

of Limestone CaCO 3 + H 2 O and CO 2 Ca 2+ + 2 HCO 3

between moving parts of the Earth s crust - active,

Victoria, Australia 5 km Faults are rarely single

$complex 3-D objects faults fractures joints 1000 km$ overburden, Gerolstein, Germany 30 m 1.

4 Chemical Alteration of Cap Rocks Faults NE Otway Range SW Bambra Fault Zone Kl Qrt 100 m Dissolution of Limestone CaCO 3 + H 2 O and CO 2 Ca HCO 3 - Schrattenkalk, Austrian Alps Tmi Faults are joints between moving parts of the Earth s crust - active, slowly creeping - rupture earthquake fault zone in Victoria, Australia 5 km Faults are rarely single translocation planes, but usually wider fault zones, complex 3-D objects faults fractures joints 1000 km grain size Faults faulted Bunter sandstone and overburden, Gerolstein, Germany 30 m 1.5 m brittle deformation of unconsolidated sand layer, Hambach lignite mine, Germany 4

Faults - natural sources of CO 2 and brine are often linked to faults -

barriers to fluid flow - can confine reservoirs and trap oil and

difference ~10m N S Seeon sonar immage and map of fault-bound CO 2

deformation - fault breccia in brittle rocks - clay smear in plastic

properties - permeable = pathways for leakage of CO 2 and formation

5 Faults - natural sources of CO 2 and brine are often linked to faults - related to recent crustal extension Tight Faults - are often efficient barriers to fluid flow - can confine reservoirs and trap oil and natural gas - can separate reservoir compartments with 100 bar pressure difference ~10m N S Seeon sonar immage and map of fault-bound CO 2 sources in the Eifel, Germany (May, 2005) hydrocarbon fields fault-traps (after Pasternak et al. 2010) Tight Faults Faults usually contain the products of rock deformation - fault breccia in brittle rocks - clay smear in plastic rocks - re-crystallized quartz grains - minerals like calcite or quartz Tight or Permeable? Faults are always a problem: seismic characterization hydraulic properties - permeable = pathways for leakage of CO 2 and formation water - tight faults = geotechnical barrier reducing capacity and injectivity - unknown = risk partly quartz-cemented fault breccia Rhens, Germany calcite vains in shear zone quartz cemented fault breccia 5

Omnipresent Faults Large faults usually are active over long times with repeated cycles of stress

mapping of faults - determination of hydraulic and geo-mechanical properties - investigate neo-tectonic

Röhling, 2000 (after: Baldschuhn and Kockel, 1997) seismic image of crestal faults in an anticlinal

of old impermeable faults could create pathways for CO 2 Recommendation Active faults: stay away if you

conditions and orientation - geo-mecanical models reveal fault strength - Areas of crustal extension

6 Omnipresent Faults Large faults usually are active over long times with repeated cycles of stress build-up, deformation, rupture, fluid percolation, mineral precipitation and sealing (fault valve mechanism). Fault Characterization Fault characterization is essential for storage safety - identification and 3-D mapping of faults - determination of hydraulic and geo-mechanical properties - investigate neo-tectonic activity (past 10 Mio. a) S. Röhling, 2000 (after: Baldschuhn and Kockel, 1997) seismic image of crestal faults in an anticlinal structure, North Sea Reactivation of Faults - Stresses induced by CO 2 injection may cause reactivation of old impermeable faults could create pathways for CO 2 Recommendation Active faults: stay away if you can! - Injection of fluids can trigger seismicity (lubricant) - Reactivation depends on existing stress conditions and orientation - geo-mecanical models reveal fault strength - Areas of crustal extension are less suitable for CO 2 storage Old, sealed faults: a) use reservoir simulator to develop injection strategy b) conduct geo-mechanical analysis to predict reactivation risk and possible leakage rates U.S. fracing of geothermal aquifer fault strenght simulation, Chiaramonte et al

Continuity and structure of Cap Rock Formations Spill points Wredenhagen x

(regional salt / fresh water barrier) 30 km spill points and potential

Field Exploration North Sea Hydrocarbon Field Heriot Watt University

7 Continuity and structure of Cap Rock Formations Spill points Wredenhagen x Zechlin x Netzeband 50 km depth of the Rupel clay barrier in North Germany (regional salt / fresh water barrier) 30 km spill points and potential migration pathways out of a proposed storage structure Knowledge after Field Exploration North Sea Hydrocarbon Field Heriot Watt University Structure after 10 a of Development North Sea Hydrocarbon Field Heriot Watt University 7

Uncertainty Uncertain exploration data and progress in knowledge during operation are a characteristic of all geotechnical activities Mobilization of unconsolidated

updating: Geological model (history matching) Hazard assessment after Utsira sandstone Variety of common phenomena in sedimentary basins, depending on rock

sonar, outcrops: North Sea Hydrocarbon field before and after development Mobilized sediment and fluids can penetrate through low permeable, clay-rich unconsolidated

8 Uncertainty Uncertain exploration data and progress in knowledge during operation are a characteristic of all geotechnical activities Mobilization of unconsolidated sediments in young sedimentary basins by - Fluid pressure - Under-compaction (gravity) - Gas accumulations (buoyancy) - Earthquakes before Legal requirement (EU) for updating: Geological model (history matching) Hazard assessment after Utsira sandstone Variety of common phenomena in sedimentary basins, depending on rock properties, depth: Clastic dikes, mud diapirs, pipes, polygonal faults gas seeps mud, volcanoes and pockmarks under water are visible in seismics, surface features, sonar, outcrops: North Sea Hydrocarbon field before and after development Mobilized sediment and fluids can penetrate through low permeable, clay-rich unconsolidated sediments! Clastic Dyke Mud Volcano b 1 m 1 m sandstone dyke in mudstone (Miocene turbidite, Hikurangi trough, NZ) mud volcano, NZ cold spring, CO 2, CH 4, brine (25 g/l), crude oil 8

9 Well-triggered Mud Volcano Detection of Leakage natural CO 2 spring Carex sp. Spiegel online Mud volcano Lusi, Java CO 2 flux measurement sonar image of lake floor CO 2 vent Leakage Control Few possibilities, little experience e.g. release of reservoir pressure through - lower injection rates - use of other injection wells - production and re-injection of CO 2 into adjacent compartments or reserve aquifers Prevention Preventive Actions - Thorough site exploration - Careful site selection - Reserve aquifers - Risk analysis - Safety and emergency planning - Geotechnical prevention - Monitoring of operations - Adequate well sealing natural CO 2 vent Polygonum arenastrum in mofette Natural gas storage facilities and Olympic Stadium in Berlin 9

5 IEAGHG CCS Summer School. Geological storage of carbon dioxide (a simple solution)

5 IEAGHG CCS Summer School. Geological storage of carbon dioxide (a simple solution) Storage 1- Reservoirs, Traps, Seals and Storage Capacity for Storage Geological storage of carbon dioxide (a simple solution) Professor John Kaldi Chief Scientist, CO2CRC Australian School of Petroleum,