1 ΑΝΘΡΩΠΙΝΑ ΔΙΚΤΥΑ ΕΡΕΥΝΗΤΙΚΗΣ ΚΑΙ ΤΕΧΝΟΛΟΓΙΚΗΣ ΕΠΙΜΟΡΦΩΣΗΣ «ΤΕΧΝΟΛΟΓΙΚΟ ΔΥΝΑΜΙΚΟ ΓΙΑ ΤΗΝ ΜΕΙΩΣΗ ΤΩΝ ΕΚΠΟΜΠΩΝ ΔΙΟΞΕΙΔΙΟΥ ΤΟΥ ΑΝΘΡΑΚΑ ΔΥΝΑΤΟΤΗΤΕΣ ΠΡΟΟΠΤΙΚΕΣ ΤΩΝ ΕΛΛΗΝΙΚΩΝ ΕΠΙΧΕΙΡΗΣΕΩΝ» Δρ. Ν. Κούκουζας Πτολεμαΐδα, Δεκέμβριος 2007
2 Content Εθνικό Κέντρο Έρευνας και Τεχνολογικής Ανάπτυξης / Climate change effects Potential of CCS technologies CO 2 capture technologies and Storage Options Trapping mechanisms Basin-Scale Screening criteria for CO2 geological Storage Types of CO2 Geological Storage Projects CO 2 geological storage potential
4 The increase of atmosphere s natural warming capacity - Global warming - is caused due to the increase of human-induced GHGs.
5 Greenhouse gas effects General temperature increase Ice/glacier/pole cap melting Rise in sea level/coastal flooding Change of ocean ph/ocean life Effect on ocean currents and related large scale climate Regional cloud formation, impact on weather conditions, precipitation changes, floods Severe sectorial meteorological changes, intense storms, extreme droughts
7 Contribution of different gases to the anthropogenic greenhouse effect
8 The greatest increase of CO2 emissions originates from power generation and transport In Europe Energy sector is responsible for 80% of the EU-greenhouse gas (GHG) emission 93% of the EU-CO2 emission million tonnes of CO Power Generation Other Transformation Industry Transport Other Sectors Source: IEA WEO 2004
9 By 2030 energy use forecast to grow by 60% World Primary Energy Demand Fossil fuels projected to remain dominant energy source accounting for almost 90% of the growth in energy demand Source: IEA WEO 2004
10 Global CO 2 emissions grow by about 60% by Mt of CO OECD Transition economies Developing countries Source: IEA WEO 2004
11 CCS will plays a significant role in GHG mitigation 150 In the context of the long term objective of 60 per cent reduction by 2050 CCS is a medium term ( ) technology. Worldwide CO2 emissions (billion ton CO2/year) Energy efficiency Renewable energy CO2 capture and storage Fossil fuels Year Source: GESTCO project, Hendriks, Ecofys
12 Advantages of CCS technologies as a climate change mitigation option Continued use of available fossil fuel resources Sufficient storage capacity Capture technologies involve the highest costs associated with CCS BUT over the next decade the cost of capture could be reduced by %. Health, safety and environment risks for geological storage are low, and the level of risk will decline over time. Potential bridging technology from a current fossil-fuel energy-based world to a renewable energy-based one in the future.
13 Capture Transport Geological Storage
14 Overview of CO2 Capture processes
16 Reservoirs and Seals In general a reservoir / seal pair consist of: Porous and permeable reservoir rock that can contain (a mixture of) gas and liquid - Rocks with porosity of typically 5-30% of volume of the rock Overlain by a seal ( non permeable rock) layer Typical seal permeability is < md Typical Reservoir size is km^3
17 Porosity is the storage space in the rock for fluids and is shown by the blue spaces in this photomicrograph of a thin slice through a reservoir sandstone. Permeability is a measure of the ability of the rock to allow fluid flow. Permeability is strongly affected by the geometry of the porosity inparticular thesizeofthespacesconnecting theporesintherock
18 Suitability of basins for CO2 geological storage Sedimentary basins are suitable for CO2 storage due to the right type of porous and permeable rocks for storage and injection, such as sandstones and carbonates, and the low permeability-toimpermeable rocks needed for sealing, such as shales and evaporitic beds. Igneous and metamorphic rocks generally are not suitable for CO2 storage because they do not possess the necessary porosity and permeability that would allow injection and storage.
19 Sandstone Roughly 20% of sedimentary rocks Consists mainly of quartz, sometimes feldspar and other minerals High permeability Medium porosity Often contain liquids or gases (water, oil or gas)
20 Shale (clay rich rocks) Most abundant sedimentary rock Originates from mechanical and chemical weathering of silicate minerals Transported by water and deposited in quit environments (lakes, floodplains) Very fine particles Very low permeability High porosity Often forms a sealing barrier to liquid movement
21 Limestone Roughly 20% of sedimentary rocks Originates mainly from the precipitation and accumulation of material of biochemical origin Consists mainly of the mineral calcite Transported and deposited in water Low to medium permeability High porosity
22 Rock salt Originates from the precipitation of minerals by the evaporation of seawater Consist mainly of the mineral halite very low permeability and porosity Flows plastically (with very little fracturing) when under pressure Tends to move upwards due to low density and form salt domes (m/year) Capable to serve as a lubricant or as an impermeable seal
23 Trapping mechanisms Hydrogeological trapping - traps the carbon dioxide into flow systems for geological periods of time Phase trapping;- strips out the CO2 as an immobile liquid or gas phase Geochemical trapping - converts the carbon dioxide to aqueous species and carbonate minerals rendering it immobile.
24 Hydrodynamic (hydrogeological) trapping in saline aquifers. Carbon dioxide can be injected into deep aquifers by displacing the saline formation water CO2 is expected to migrate under the force of buoyancy towards the surface If the aquifer is well-bounded by aquitards, migration of the CO2 would be slowly The time needed for a volume of fluid to reach the surface from the deep basin is measured on a geological time scale (more than 10 5 years) Migration paths in hydrodynamic traps in deep saline aquifers: a) trapping in regional-scale systems, b) in interconnected systems through faults and fractures
25 Geologic (hydrogeological) trapping in reservoirs structural traps (anticlines, unconformities or faults) stratigraphic traps (change in type of rock layer) Folding and anticlines Folding and anticlines Faults and unconformities
26 Phase Trapping In the case of injection of CO2, the water will reach irreducible saturation as the CO2 bubble displaces it. The CO2 will reach irreducible saturation after injection ceases and the natural flow of the aquifer displaces the CO2. Irreducible saturation for gases can range from 2 to 25%. Consequently, a CO2 bubble formed around the base of an injection well will be dispersed by any natural water flow through the porous media until all of the CO2 is trapped by stripping, through retention in the form of the irreducible saturation.
27 Geochemical trapping Adsorption the preferential adsorption of gaseous CO2 onto the coal matrix because of its higher affinity to coal than that of methane; Solubility up to 30% of injected CO2 will dissolve in the formation water for an engineering time scale; Ionic Silicate or carbonate minerals present in the aquifer neutralize the acid added to the formation water by the addition of CO2. These reactions fix the CO2 as an ionic species in the formation water. Mineral - Silicate minerals present in the aquifer neutralize the acid added to the formation water by the addition of CO2. These reactions can fix the CO2 as a mineral and result in permanent trapping.
28 Contribution of trapping mechanisms to the security of CO2 geological storage
29 Basin-Scale Screening Criteria Based on: Geological characteristics Hydrodynamic and geothermal regimes Basin resources and maturity Industry maturity and infrastructure Economic and societal aspects
30 More suitable sedimentary basins
31 Basin characteristics important for storage Adequate thickness >1000 m; Strong reservoir and seal pair; Not highly faulted, fractured or located in fold belts; Strongly harmonious sequences; No volcanogenic sediments; No significant diagenesis.
32 Geological characteristics important for CO2 storage sites Adequate porosity, thickness and permeability - The presence of a storage formation of adequate porosity and thickness (for capacity) and permeability (for injectivity) is critical. Depth greater than 800 m for CO2 in supercritical state Confining unit cap - shale, salt or anhydrite beds, to ensure CO2 storage and prevent its escape into overlying, shallower units and ultimately to the surface.
33 Cold Basins: Low surface temperature and/or geothermal gradients more favorable (higher CO2 density, at shallower depths) Warms basins: High surface temperature and geothermal gradients less favorable (lower CO2 density, larger depths needed Geothermal regimes
34 Basin Maturity Fossil-energy potential (oil and gas, coals) and degree of exploration and production Mature: Rich in Energy resources, advanced production Poor: No or poor in hydrocarbon resources
35 Industry Maturity and Infrastructure Developed continental basins: Access roads, pipelines, wells Developed marine basins: Drilling and production platforms
36 Economic and Societal Aspects Cost: Affected by basin location, marine or continental, climatic conditions, transportation distances, injection depth Legal: Jurisdiction over resources, liability, regulatory regime Public Acceptance Proximity to population centers, accept or reject projects
37 Prospective geological storage areas in sedimentary basins
38 How much storage potential is available? Study Location World - Koide 92 World - van der M eer 92 World - IEA 92 Wo rld - H endriks and B lo k 93 Wo rld - H endriks and B lo k 94 World - IEA 94 Wo rld - H endriks 94 World - Hendriks & Blok 95 World - Turkenburg 97 Wo rld - IP C C 01/A rc 00 World - ECOFYS & TNO-NITG 2002 Wo rld - B ruant 02 World 1 - GEOSEQ World 2 - Beecy & Kuuskra 01 World 3 - IEA Wo rld - D o o ley and F riedman World - ECOFYS Euro pe - van der Straaten Europe - Boe et al N W Euro pe - Jo ule R epo rt Western Europe - Dooley amd Friedman Eastern Europe - Dooley and Friedman Former Soviet Union - Dooley and Combined Europe - Dooley and Friedman Western Europe - ECOFYS Eastern Europe - ECOFYS Total Europe - ECOFYS USA - Bergman & Winter )M t Simo n Sandsto ne (Ohio )M t Simo n Sandsto ne (M idwest USA M t Simo n Sandsto ne USA - Dooley and Friedman USA - ECOFYS Alberta Basin (Canada) - Total Alberta Basin (Canada) - Viking Fmn C anada - D o o ley and F riedman C anada - EC OF YS Australia - Bradshaw et al 2002 Australia/NZ - Dooley and Friedman Oceania - ECOFYS Japan - ECOFYS Japan - Dooley and Friedman Japan From Bradshaw et al., 2005: Discussion Paper on CO 2 Storage Capacity Estimation CSLF Task Force on Capacity ,000 GT CO 2 10,000 World WORLD: : , GT Europe : GT EUROPE: GT USA : GT USA: GT Canada : GT CANADA: GT Australia : GT AUSTRALIA: GT Japan : 0 80 GT JAPAN: 0-80 GT 100,000 1,000,000
39 Storage potential The potential storage capacity covers at least several decades of current global CO2 emissions (approx. 30 Gt CO2/year). The estimated range of the economic potential for CCS varies between Gt CO2, which would mean that 15-55% of the world-wide mitigation effort by 2100 could be achieved through the implementation of CCS. Gton CO Gton CO 2 2 Depleted oil fields Depleted gas fields Enhanced oil recovery Unminable coal seams >15 >73 Saline aquifers* , ,000 1 Source: (IEA GHG, 2001) 2 Source: (Edmonds, 2000)
40 European geological storage capacity 200 to up to 1550 Gt CO to 1500 Gt of CO2 in deep saline formations mainly in the North Sea. The total capacity of hydrocarbon fields is estimated at more than 40 Gt CO2, 7 Gt of which can be stored in oil reservoirs. The storage capacity of unmineable coal seams is estimated at 6 Gt CO2.
41 Enhanced oil recovery (EOR) CO2-EOR is applied on commercial scale in the USA, Canada, Turkey and Trinidad and Tobago. The majority of projects are situated in the Permian basin in the USA. Currently about 43 million tonnes/year of CO2 is being injected; the majority (~ 75%) being CO2 from geological reservoirs and the remaining part from industrial sources. CO2 injection into water flooded oil reservoirs could yield an extra of 4-12% OOIP oil production 40% of oil reserves can be recovered through primary (~25 to 30%) and secondary (~10%) processes. The use of CO2 can enhance the recovery of around 10 to 12% of the remaining oil.
42 By injecting CO2 into oil reservoirs oil is mobilized through miscible or immiscible displacement increasing oil recovery. Enhanced oil recovery (EOR) The average retention of the injected CO2 in several reservoirs is around 60% while m3 of CO2 is required to produce 1barrel of oil.
43 Enhanced oil recovery (EOR) When introduced in the reservoir CO2 interacts chemically and physically with the reservoir rock and the contained oil, creating favourable conditions that improve oil recovery such as: (i) the reduction of the capillary forces that inhibit oil flow through the pores of the reservoir by reducing the interfacial tension between oil and the reservoir rock; (ii) the expansion of the volume of the oil (oil swelling) and the subsequent reduction of its viscosity; (iii) the development of favourable complex phase changes in the oil that increase its fluidity; (iv) the maintenance of favourable mobility characteristics for oil and CO2 to improve the volume sweep (replacement) efficiency.
44 Two processes for CO2-EOR: Enhanced oil recovery (EOR) Miscible displacement where the injected gas and the hydrocarbons are completely miscible and form a single-phase fluid. Immiscible displacement occurs at pressures below a minimum miscible pressure (MMP) of the oil, in which there is less interchange of components or mixing zones between the gas injected and the reservoir fluid.
45 Miscible CO2 displacement method A schematic of a WAG miscible CO2-EOR operation
46 Immiscible CO2 displacement method CO2 is typically injected in GSGI mode at slow rates at the crest of the reservoir aiming at filling the pore volume of the reservoir rock. The injected gas creates an artificial gas cap, pushing oil simultaneously downwards and towards the rim of the reservoir where the producing wells are located. The presence of water within the reservoir reduces the effectiveness of the process as it inhibits oil flow. This process may not be effective when applied after significant water flooding.
47 Immiscible displacement technique
48 Criteria Specific to Enhanced Oil Recovery Light oil (25 to 48 API) Reservoir pressure greater than Minimum Miscibility Pressure Preferably thin net pay (<20 m) Homogeneous reservoir
49 Enhanced Gas Recovery (EGR) Using CO2 for enhanced gas recovery (EGR) is a speculative method for repressurizing depleted gas fields that can be applied to certain fields when 80-90% of the gas has been produced. CO2 EGR has not yet been applied anywhere in the world.
50 Enhanced Gas Recovery (EGR) The injected CO2 will flow in the reservoir due to pressure and gravitational effects. CO2 is denser than CH4 at all relevant pressures and temperatures and will tend to flow downwards, displacing CH4 gas and repressurizing the reservoir Given an initial pressure of 120 bar, another 5-15% of the initial gas in place could be recovered using EGR. About 1.8 GJ of gas could be recovered per tonne of CO2 stored, if a whole reservoir was filled with CO2 up to its original pressure. The potential for CO2 use for EGR might be larger than for EOR but the EGR revenues per tonne of CO2 are lower than for EOR.
51 Enhanced Coal Bed Methane Projects (ECBM) Conventional coalbed methane recovery may achieve 40-50% recovery while the recovery increases to % in the case of ECBM. ( ECBM is limited to coal seams that will not be mined The technology is only in the demonstration phase
52 Enhanced Coal Bed Methane Projects (ECBM) Coal contains micro-pores (r = nm) suitable for adsorption of gases, such as CO 2 (r = ca. 0.3 nm) Higher affinity to adsorb CO 2 than CH 4 One methane molecule can be replaced by at least two molecules of o CO 2 Ratio CO 2 /CH 4 depends on the maturity and type of coal Coal plastization and swelling can occur due to the presence of CO 2 and this reduces permeability
53 Enhanced Coal Bed Methane Projects (ECBM) Adsorption-desorption mechanism
54 Enhanced Coal Bed Methane Projects (ECBM) Adsorption of various gases on coal
55 Enhanced Coal Bed Methane Projects (ECBM) Factors affecting coal adsorption Coal rank Peat lignite bituminous coal anthracite Pore structure and size Moist content (rank dependent) Coal composition Presence of different macerals and minerals Moisture content Water molecules block adsorption sites of pore system ph change Temperature adsorption rates decrease with increasing T
56 Enhanced Coal Bed Methane Projects (ECBM) No clear whether supercritical CO2 is adsorbed by coal, occupies the pore space like a fluid with very low viscosity, or infuses into the coal matrix. Thus, CO2 is injected in gaseous phase. For hydrostatic conditions and average geothermal gradients this would correspond to depths in the m range.
57 Enhanced Coal Bed Methane Projects (ECBM) CO2 adsorption related to pressure for wet and dry coal CO2 adsorbed [mmole/g coal daf] Equilibrium Pressure [MPa]
58 Criteria Specific to Enhanced Coalbed Methane Recovery A homogeneous reservoir, laterally continuous and vertically isolated from surrounding strata; Minimally faulted and folded; At least 1-5 millidarcies (md) permeability. High methane content; Stratigraphically concentrated coal seams are preferred over multiple thin seams; A possibility to use or export methane (pipeline) and CO2 availability (local power plant, industry or pipeline).
59 CO2 storage in deep saline aquifers Saline Aquifers are defined as porous and permeable reservoir rocks that contain saline fluid in the pore spaces between the rock grains. They generally occur at depths greater than aquifers that contain potable water. Water in aquifers deep below the ground in sedimentary basins is confined by overlying and underlying aquitards and/or aquicludes, usually has a high content of dissolved solids (brackish water and brine) and may have been there for millions of years. Because of the confined character of these aquifers, they have been proposed as locations for CO2 storage.
60 CO2 storage in deep saline aquifers Storage in confined aquifers relies on trapping of the buoyant CO2 by structural (e.g. anticlines) and /or stratigraphic features, and is closely analogous to gas storage schemes in hydrocarbon fields, or indeed to natural gas storage in subsurface aquifers. In simple structural traps, volumes and migration pathways of the injected CO2 can be predicted and reservoir models constructed with a higher degree of certainty than in an unconfined aquifer.
61 CO2 storage in deep saline aquifers CO2 is injected into large aquifers without specific large structural or stratigraphic closures. The injected CO2 migrates upwards along the most permeable pathway until it reachs the impermeable cap rock. Next CO2 migrates laterally along the cap rock-reservoir reservoir boundary following the most permeable pathways where small domes and undulations trap effectively a proportion of the injected CO2, depending on the average roughness.
62 CO2 storage in deep saline aquifers As these minor structural closures are filled, the CO2 spills out and continues to migrate laterally. In unconfined aquifers over time the CO2 will likely be distributed over a large area and in low concentrations increasing thet volumes that can be stored in these small perturbations on the top reservoir surface. Because of the likely large migration path lengths, the component of storage due to dissolution is increased significantly and thus, probably in many cases with the absence of vertical migration pathways the CO2 is unlikely to reach the surface. This type of storage has been demonstrated at Sleipner
63 . Εθνικό Κέντρο Έρευνας και Τεχνολογικής Ανάπτυξης / Depleted oil and gas fields Established seal and trap.. These structures have effectively stored hydrocarbons for millions of years, proving the integrity of the reservoir seal and the permanence of the fluid trap. Existing Infrastructure.. Some of the equipment installed on the surface or underground for oil or gas recovery may be re-used for injecting and storing CO2 lowering the initial capital requirements for establishing the t CO2 storage facility. Value-Added Products: : The revenues derived from the additional oil production could offset some (or all) of the costs associated with CO2 storage. Legal barriers are less strict for the injection of CO2 into hydrocarbon reservoirs compared to aquifers. Injection of CO2 for EOR is not prohibited under the London and OSPAR treaties.
64 Advantages and disadvantages IEA, GHG, 2004
65 Maximum potential CO2 storage capacity in Prinos offshore depleted oil field compared to the annual emissions from major point sources. Oil field (10 6 t CO2) Total storage capacity (10 6 t CO2) Annual point source CO2 emissions (10 6 t CO2) Number of years storage capacity from current point sources (approx.) (GESTCO PROJECT)
66 CO2 storage capacity in saline aquifers -Greece Aquifer Position Storage capacity (Mt CO2) Prinos W. Thessaloniki W. Thessaloniki sandstone offshore 1343 onshore 459 onshore 145 Alexandria Mesohellenic basin onshore 34 onshore 360 Total 2345 (GESTCO PROJECT)
67 Conclusions With appropriate site selection informed by available subsurface information, a monitoring program to detect problems, a regulatory system, and the appropriate use of remediation methods to stop or control CO2releases if they arise, the local health, safety, and environment risks of geological storage would be comparable to risks of current activities such as natural gas storage, EOR, anddeepundergrounddisposalofacidgas. IPCC, 2005