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10+ years of the IEA-GHG Weyburn-Midale CO2 monitoring and storage project: Successes and lessons learned from multiple hydrogeological investigations
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Energy Procedia
Energy Procedia 4 (2011) 3636–3643 Energy Procedia 00 (2010) 000–000
www.elsevier.com/locate/procedia www.elsevier.com/locate/XXX
GHGT-10
10+ years of the IEA-GHG Weyburn-Midale CO2 monitoring and storage project: successes and lessons learned from multiple hydrogeological investigations. Ben Rostrona, Steve Whittakerb a1 b
University of Alberta, 1-26 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3,
Petroleum Technology Research Centre, 6 Research Drive, Regina, Saskatchewan, Canada, S4S 7J7. Elsevier use only: Received date here; revised date here; accepted date here
Abstract
In July 2000, the IEA-GHG Weyburn CO2 monitoring and storage project was initiated to study the geological storage of CO2 as part of an EOR project planned for the Weyburn Field in Saskatchewan, Canada. Over the period 2000-present, a diverse group of researchers have worked on: assessing the integrity of the geosphere encompassing the Weyburn oil pool for effective long-term storage of CO2; monitoring the movement of the injected CO2, and assessing the risk of migration of CO2 from the injection zone to the surface. Learnings from 10+ years of hydrogeological investigations include: i) low flow rates and favourable flow directions indicate the Weyburn reservoir is an excellent place to store CO2; ii) shallow groundwater monitoring reveals no significant changes in water chemistry that can be attributed to storage operations (interactions); and iii) co-ordination and integration of multiple hydrogeological research programs on the same site can be rewarding but challenging. c 2010 © Ltd. rightsLtd. reserved ⃝ 2011 Elsevier Published by All Elsevier Keywords: Weyburn-Midale Project; CO2 sequestration; hydrogeology, hydrochemistry, site characterization.
1. Introduction In July 2000, a major research project was initiated to study the geological storage of CO2 as part of a 5000 tonnes/day EOR project planned for the Weyburn Field in Saskatchewan, Canada (Figure 1). Major objectives of the IEA-GHG Weyburn CO2 monitoring and storage project included: assessing the integrity of the geosphere encompassing the Weyburn oil pool for effective long-term storage of CO2; monitoring the movement of the injected CO2, and assessing the risk of migration of CO2 from the injection zone (approximately 1500 metres depth) to the
doi:10.1016/j.egypro.2011.02.294
B. Rostron, S. Whittaker / Energy Procedia 4 (2011) 3636–3643
3637
surface. Initial injection of CO2 began in October 2000 and continues to date. By June 2010, more than 16 Mtonnes of CO2 have been stored in the Weyburn reservoir, at a current injection rate over 250 mmscf/day (~13,000 tonnes/day). An operational overview is included elsewhere in this volume [1]. Hydrogeological investigations played a key role in the IEA-GHG Weyburn CO2 monitoring and storage project. Over the period 2000-present, a diverse group of researchers worked on hydrogeological/hydrochemical monitoring above the field and hydrogeological characterizations at both the regional (100 km beyond the field; Figure 1) and detailed scale (10 km in and around the field); on shallow (less than 250 m) and deep (>250 m) aquifers; and a detailed examination of the hydraulics of the injection horizon (Midale Aquifer) and adjacent units (Ratcliffe and Frobisher aquifers; Figure 2). A parallel hydrogeological study was also conducted on the area for a European Union (EU) study. For the most part, research has been conducted in two major phases: Phase I (2000-2004) and the Final Phase (2007-2011), with some monitoring and on-going research conducted in between. Project findings including hydrogeological results from Phase I have been previously reported (e.g., [2], [3]). Initial results from the Final Phase of the project have also been reported (e.g., [4], [5], [6], [7]). A summary of the long-term findings from over 10 years of hydrogeology research forms the basis of this paper. 2. Results Results of the 2000-2004 hydrogeological characterizations ([3], [8]) showed: i) a strong regional aquitard (Watrous) separates the deep hydrogeological system, including the Midale Aquifer, from a shallow (1000 to 300 m depth) hydrogeologic system. There is no evidence for regional flow of formation waters from the Midale Aquifer across the Watrous Aquitard into the upper aquifers within the project area. The Watrous Aquitard serves as an excellent primary seal for CO2 injected into the Midale reservoir at the Weyburn Field; ii) low flow velocities (<1 m/yr) and favourable (horizontal) flow directions in the Midale Aquifer (e.g., Figure 3) prevent formation water flow from acting as an effective transport agent, thus hydrodynamically trapping injected CO2; iii) the steep salinity gradient (TDS <50 to >150 g/L) across the CO2 injection area must be accounted for in geochemical modelling and risk assessment; iv) the deep hydrogeological regime beneath the reservoir may be neglected in order to simplify the Risk Assessment system models; v) high flow velocities in overlying aquifers (1-10 m/yr) are important input parameters to the system model for scenario analysis of any CO2 leakage into overlying horizons. Results of the hydrogeological characterizations were used for a performance assessment in the Phase I of the project that concluded the risk of CO2 movement to the biosphere was very small [2]. A shallow water-well monitoring and sampling program was initiated in 2000 over the Phase 1A CO2 injection area to provide background water levels and groundwater chemistry data for ongoing monitoring. Over the period 2000-2009, sampling programs have been conducted seven times, (2000 twice, 2001 twice, 2002, 2006, 2009) on approximately 60 different wells mostly domestic water wells. Results show the background water chemistry in the area is highly variable, generally of the Ca-Mg/SO4-HCO3 type with Total Dissolved Solids (TDS) ranging
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from approximately 300 – 2000 mg/L, and typically elevated in nitrate. Due to well use-changes and access/other issues approximately 20 of the sites have been sampled multiple times between 2000-2009. Of the wells that have a time series of samples: over 70% exhibit no significant changes in water chemistry over time, approximately 20% exhibit variability from one sampling round to the next, and the remainder demonstrate a change over time that is either “improving” the water quality (i.e., TDS lower) or a result of increasing SO4 and hence TDS. In all cases, the wells that show variability and/or significant changes in chemistry are shallow (<30 m depth) farm wells where the chemistry changes are attributed to near surface operations. In none of the shallow wells sampled was a significant, long-term increase in CO2/HCO3 detected. One area of research that proved challenging was the co-ordination between the various groups working on the hydrogeology of the area, both in terms of spatial overlap (vertically and horizontally), and consistency of results. Spatial overlap was managed successfully by careful integration between the “shallow” and “deep” hydrogeological studies (e.g., [8]). On the other hand, integration of the multiple “regional” investigations, in particular with the European Union study proved problematic and was never resolved. The unfortunate result of this was that the EU hydrogeology study utilized an out-dated hydrostratigraphic framework, in particular for the injection aquifer (Midale). The EU study (e.g., [9]) relied on an older regional hydrogeological study [10] that grouped all Mississippian-aged aquifers in the basin into one flow unit. In contrast, geological mapping results from Phase I of the project [8] enabled the creation of separate (i.e., geologically-based) Mississippian aquifers, including the Midale Aquifer injection horizon [3]. One unfortunate result of this was that later CO2 migration modelling based on the “combined” Mississippian aquifer (e.g., [9], [11]) predicts migration directions (Figure 4) that are physically impossible: the Midale Aquifer does not exist in the area predicted by the modelling. This can be seen by a comparison of Figure 3 (in particular the position of the zero edge of the Midale Aquifer), and the northeastern migration directions shown in Figure 4. Clearly the modelled CO2 migration rates, and times, on Figure 4 have no meaning if the aquifer does not exist in that are. This unfortunate situation is being rectified in the Final Phase of the research program. 3. Conclusions Over the period 2000-present, a diverse group of researchers have contributed to the understanding of the hydrogeology and hydrochemistry of the Weyburn oil field and surrounding area for the IEA-GHG Weyburn CO2 monitoring and storage project. Main learnings from 10+ years of hydrogeological investigations at this site include: i) low flow rates and favourable flow directions indicate the Weyburn reservoir is an excellent place to store CO2; ii) shallow groundwater monitoring reveals no significant changes in water chemistry that can be attributed to storage operations (interactions); and iii) co-ordination and integration of multiple hydrogeological research programs on the same site improved the understanding of the site, but proved challenging to manage. In the Final Phase of the project (2007-2011) further hydrogeology investigations are underway aiming to enhance the knowledge of the site, and to capture the results as part of a “Best Practises Manual” [4].
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4. References 1. Whittaker S, Rostron B, Hawkes C, Gardner C, White J, Johnson J, et al. A decade of CO2 injection into depleting oil fields: monitoring and research activities of the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project. Energy Procedia 2010; this volume. 2. Wilson M, Monea, M (eds.). IEA-GHG Weyburn CO2 Monitoring & Storage Project Summary Report 2000-2004. Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, 2004, Volume 3, 273 p. 3. Khan, DK, Rostron, BJ. Regional hydrogeological investigation around the IEA-GHG Weyburn CO2 Monitoring and Storage Project Site. In: Rubin, E.S., Keith, D.W., and C.F. Gilboy (eds.), Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, Volume 1, Peer Reviewed Papers and Overviews, p. 741-750. 4. Preston C, Whittaker S, Rostron B, Chalaturnyk R, White D, Hawkes C, et al. IEA GHG Weyburn-Midale CO2 monitoring and storage project – moving forward with the Final Phase. Energy Procedia 2009; 1:1742-1750. 5. Jensen GKS, Nickel EH, Whittaker S, Rostron BJ. Geological model and hydrogeological framework of an active CO2 sequestration project in the WeyburnMidale area, Saskatchewan: Leading to a further understanding of possible CO2 migration. Energy Procedia 2009; 1:2983-2989. 6. Nickel E, Jensen J, Rostron B. Refinement of the Weyburn geological model: Overcoming challenges in data compilation and management. Energy Procedia 2010; this volume. 7. Jensen J, Nickel E, Rostron B. Site assessment update at Weyburn-Midale CO2 sequestration project, Saskatchewan Canada: new results at an active CO2 sequestration site. Energy Procedia 2010; this volume. 8. Whittaker SG, Rostron B, Khan D, Maathuis H, Hajnal Z, Qing H, et al. Theme 1: Geological Characterization. In: M. Wilson and M. Monea (eds.), IEA-GHG Weyburn Monitoring and Storage Project Summary Report 2000-2004. Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, Volume 3, p. 15-69. 9. Riding JB, Rochelle CA. Subsurface characterization and geological monitoring of the CO2 injection operation at Weyburn, Saskatchewan, Canada. Geological Society, London, Special Publications 2009; 313:227-256. 10. Bachu S, Hitchon B. Regional-scale flow of formation waters in the Williston Basin. AAPG Bulletin 1996; 80:248-264. 11. Audigane P, Le-Nindre YM. Hydrodynamic modelling of the Mississippian aquifer at Weyburn, Saskatchewan, Canada. Bureau de Recherches Geologiques et Minieres Report BRGM/RP-52786-FR.
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Figure 1: Location of the Weyburn oilfield within the Williston Basin (Canada-USA). Modified from Preston et al, 2009.
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Figure 2: Stratigraphy and hydrostratigraphy used for the IEA-GHG Weyburn-Midale CO2 monitoring and storage project.
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Figure 3: Regional flow directions in the Midale Aquifer (injection horizon). Contours are metres of equivalent freshwater head (EFWH) derived from Drill-Stem-Tests and other pressure measurements. Black vectors are flow directions inferred from the gradient of EFWH. Density-corrected water driving-force (WDF) vectors are shown in grey. Shaded areas indicate significant density-related flow effects, where there is a large divergence between flow directions inferred from the EFWH versus WDF. Solid black outline is the Weyburn field. Modified from Khan and Rostron, 2005.
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Figure 4: Modelled CO2 migration pathways and distances after 100,000 and 630,000 years in the Mississippian Aquifer. Weyburn field outline is shown in black. Colors are the observed salinity distribution. After Riding and Rochelle, 2009 modified from Audigane and LeNindre, 2004.
Energy Procedia
Energy Procedia 4 (2011) 3636–3643 Energy Procedia 00 (2010) 000–000
www.elsevier.com/locate/procedia www.elsevier.com/locate/XXX
GHGT-10
10+ years of the IEA-GHG Weyburn-Midale CO2 monitoring and storage project: successes and lessons learned from multiple hydrogeological investigations. Ben Rostrona, Steve Whittakerb a1 b
University of Alberta, 1-26 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3,
Petroleum Technology Research Centre, 6 Research Drive, Regina, Saskatchewan, Canada, S4S 7J7. Elsevier use only: Received date here; revised date here; accepted date here
Abstract
In July 2000, the IEA-GHG Weyburn CO2 monitoring and storage project was initiated to study the geological storage of CO2 as part of an EOR project planned for the Weyburn Field in Saskatchewan, Canada. Over the period 2000-present, a diverse group of researchers have worked on: assessing the integrity of the geosphere encompassing the Weyburn oil pool for effective long-term storage of CO2; monitoring the movement of the injected CO2, and assessing the risk of migration of CO2 from the injection zone to the surface. Learnings from 10+ years of hydrogeological investigations include: i) low flow rates and favourable flow directions indicate the Weyburn reservoir is an excellent place to store CO2; ii) shallow groundwater monitoring reveals no significant changes in water chemistry that can be attributed to storage operations (interactions); and iii) co-ordination and integration of multiple hydrogeological research programs on the same site can be rewarding but challenging. c 2010 © Ltd. rightsLtd. reserved ⃝ 2011 Elsevier Published by All Elsevier Keywords: Weyburn-Midale Project; CO2 sequestration; hydrogeology, hydrochemistry, site characterization.
1. Introduction In July 2000, a major research project was initiated to study the geological storage of CO2 as part of a 5000 tonnes/day EOR project planned for the Weyburn Field in Saskatchewan, Canada (Figure 1). Major objectives of the IEA-GHG Weyburn CO2 monitoring and storage project included: assessing the integrity of the geosphere encompassing the Weyburn oil pool for effective long-term storage of CO2; monitoring the movement of the injected CO2, and assessing the risk of migration of CO2 from the injection zone (approximately 1500 metres depth) to the
doi:10.1016/j.egypro.2011.02.294
B. Rostron, S. Whittaker / Energy Procedia 4 (2011) 3636–3643
3637
surface. Initial injection of CO2 began in October 2000 and continues to date. By June 2010, more than 16 Mtonnes of CO2 have been stored in the Weyburn reservoir, at a current injection rate over 250 mmscf/day (~13,000 tonnes/day). An operational overview is included elsewhere in this volume [1]. Hydrogeological investigations played a key role in the IEA-GHG Weyburn CO2 monitoring and storage project. Over the period 2000-present, a diverse group of researchers worked on hydrogeological/hydrochemical monitoring above the field and hydrogeological characterizations at both the regional (100 km beyond the field; Figure 1) and detailed scale (10 km in and around the field); on shallow (less than 250 m) and deep (>250 m) aquifers; and a detailed examination of the hydraulics of the injection horizon (Midale Aquifer) and adjacent units (Ratcliffe and Frobisher aquifers; Figure 2). A parallel hydrogeological study was also conducted on the area for a European Union (EU) study. For the most part, research has been conducted in two major phases: Phase I (2000-2004) and the Final Phase (2007-2011), with some monitoring and on-going research conducted in between. Project findings including hydrogeological results from Phase I have been previously reported (e.g., [2], [3]). Initial results from the Final Phase of the project have also been reported (e.g., [4], [5], [6], [7]). A summary of the long-term findings from over 10 years of hydrogeology research forms the basis of this paper. 2. Results Results of the 2000-2004 hydrogeological characterizations ([3], [8]) showed: i) a strong regional aquitard (Watrous) separates the deep hydrogeological system, including the Midale Aquifer, from a shallow (1000 to 300 m depth) hydrogeologic system. There is no evidence for regional flow of formation waters from the Midale Aquifer across the Watrous Aquitard into the upper aquifers within the project area. The Watrous Aquitard serves as an excellent primary seal for CO2 injected into the Midale reservoir at the Weyburn Field; ii) low flow velocities (<1 m/yr) and favourable (horizontal) flow directions in the Midale Aquifer (e.g., Figure 3) prevent formation water flow from acting as an effective transport agent, thus hydrodynamically trapping injected CO2; iii) the steep salinity gradient (TDS <50 to >150 g/L) across the CO2 injection area must be accounted for in geochemical modelling and risk assessment; iv) the deep hydrogeological regime beneath the reservoir may be neglected in order to simplify the Risk Assessment system models; v) high flow velocities in overlying aquifers (1-10 m/yr) are important input parameters to the system model for scenario analysis of any CO2 leakage into overlying horizons. Results of the hydrogeological characterizations were used for a performance assessment in the Phase I of the project that concluded the risk of CO2 movement to the biosphere was very small [2]. A shallow water-well monitoring and sampling program was initiated in 2000 over the Phase 1A CO2 injection area to provide background water levels and groundwater chemistry data for ongoing monitoring. Over the period 2000-2009, sampling programs have been conducted seven times, (2000 twice, 2001 twice, 2002, 2006, 2009) on approximately 60 different wells mostly domestic water wells. Results show the background water chemistry in the area is highly variable, generally of the Ca-Mg/SO4-HCO3 type with Total Dissolved Solids (TDS) ranging
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from approximately 300 – 2000 mg/L, and typically elevated in nitrate. Due to well use-changes and access/other issues approximately 20 of the sites have been sampled multiple times between 2000-2009. Of the wells that have a time series of samples: over 70% exhibit no significant changes in water chemistry over time, approximately 20% exhibit variability from one sampling round to the next, and the remainder demonstrate a change over time that is either “improving” the water quality (i.e., TDS lower) or a result of increasing SO4 and hence TDS. In all cases, the wells that show variability and/or significant changes in chemistry are shallow (<30 m depth) farm wells where the chemistry changes are attributed to near surface operations. In none of the shallow wells sampled was a significant, long-term increase in CO2/HCO3 detected. One area of research that proved challenging was the co-ordination between the various groups working on the hydrogeology of the area, both in terms of spatial overlap (vertically and horizontally), and consistency of results. Spatial overlap was managed successfully by careful integration between the “shallow” and “deep” hydrogeological studies (e.g., [8]). On the other hand, integration of the multiple “regional” investigations, in particular with the European Union study proved problematic and was never resolved. The unfortunate result of this was that the EU hydrogeology study utilized an out-dated hydrostratigraphic framework, in particular for the injection aquifer (Midale). The EU study (e.g., [9]) relied on an older regional hydrogeological study [10] that grouped all Mississippian-aged aquifers in the basin into one flow unit. In contrast, geological mapping results from Phase I of the project [8] enabled the creation of separate (i.e., geologically-based) Mississippian aquifers, including the Midale Aquifer injection horizon [3]. One unfortunate result of this was that later CO2 migration modelling based on the “combined” Mississippian aquifer (e.g., [9], [11]) predicts migration directions (Figure 4) that are physically impossible: the Midale Aquifer does not exist in the area predicted by the modelling. This can be seen by a comparison of Figure 3 (in particular the position of the zero edge of the Midale Aquifer), and the northeastern migration directions shown in Figure 4. Clearly the modelled CO2 migration rates, and times, on Figure 4 have no meaning if the aquifer does not exist in that are. This unfortunate situation is being rectified in the Final Phase of the research program. 3. Conclusions Over the period 2000-present, a diverse group of researchers have contributed to the understanding of the hydrogeology and hydrochemistry of the Weyburn oil field and surrounding area for the IEA-GHG Weyburn CO2 monitoring and storage project. Main learnings from 10+ years of hydrogeological investigations at this site include: i) low flow rates and favourable flow directions indicate the Weyburn reservoir is an excellent place to store CO2; ii) shallow groundwater monitoring reveals no significant changes in water chemistry that can be attributed to storage operations (interactions); and iii) co-ordination and integration of multiple hydrogeological research programs on the same site improved the understanding of the site, but proved challenging to manage. In the Final Phase of the project (2007-2011) further hydrogeology investigations are underway aiming to enhance the knowledge of the site, and to capture the results as part of a “Best Practises Manual” [4].
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4. References 1. Whittaker S, Rostron B, Hawkes C, Gardner C, White J, Johnson J, et al. A decade of CO2 injection into depleting oil fields: monitoring and research activities of the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project. Energy Procedia 2010; this volume. 2. Wilson M, Monea, M (eds.). IEA-GHG Weyburn CO2 Monitoring & Storage Project Summary Report 2000-2004. Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, 2004, Volume 3, 273 p. 3. Khan, DK, Rostron, BJ. Regional hydrogeological investigation around the IEA-GHG Weyburn CO2 Monitoring and Storage Project Site. In: Rubin, E.S., Keith, D.W., and C.F. Gilboy (eds.), Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, Volume 1, Peer Reviewed Papers and Overviews, p. 741-750. 4. Preston C, Whittaker S, Rostron B, Chalaturnyk R, White D, Hawkes C, et al. IEA GHG Weyburn-Midale CO2 monitoring and storage project – moving forward with the Final Phase. Energy Procedia 2009; 1:1742-1750. 5. Jensen GKS, Nickel EH, Whittaker S, Rostron BJ. Geological model and hydrogeological framework of an active CO2 sequestration project in the WeyburnMidale area, Saskatchewan: Leading to a further understanding of possible CO2 migration. Energy Procedia 2009; 1:2983-2989. 6. Nickel E, Jensen J, Rostron B. Refinement of the Weyburn geological model: Overcoming challenges in data compilation and management. Energy Procedia 2010; this volume. 7. Jensen J, Nickel E, Rostron B. Site assessment update at Weyburn-Midale CO2 sequestration project, Saskatchewan Canada: new results at an active CO2 sequestration site. Energy Procedia 2010; this volume. 8. Whittaker SG, Rostron B, Khan D, Maathuis H, Hajnal Z, Qing H, et al. Theme 1: Geological Characterization. In: M. Wilson and M. Monea (eds.), IEA-GHG Weyburn Monitoring and Storage Project Summary Report 2000-2004. Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, 2004, Vancouver, Canada, Volume 3, p. 15-69. 9. Riding JB, Rochelle CA. Subsurface characterization and geological monitoring of the CO2 injection operation at Weyburn, Saskatchewan, Canada. Geological Society, London, Special Publications 2009; 313:227-256. 10. Bachu S, Hitchon B. Regional-scale flow of formation waters in the Williston Basin. AAPG Bulletin 1996; 80:248-264. 11. Audigane P, Le-Nindre YM. Hydrodynamic modelling of the Mississippian aquifer at Weyburn, Saskatchewan, Canada. Bureau de Recherches Geologiques et Minieres Report BRGM/RP-52786-FR.
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Figure 1: Location of the Weyburn oilfield within the Williston Basin (Canada-USA). Modified from Preston et al, 2009.
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Figure 2: Stratigraphy and hydrostratigraphy used for the IEA-GHG Weyburn-Midale CO2 monitoring and storage project.
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Figure 3: Regional flow directions in the Midale Aquifer (injection horizon). Contours are metres of equivalent freshwater head (EFWH) derived from Drill-Stem-Tests and other pressure measurements. Black vectors are flow directions inferred from the gradient of EFWH. Density-corrected water driving-force (WDF) vectors are shown in grey. Shaded areas indicate significant density-related flow effects, where there is a large divergence between flow directions inferred from the EFWH versus WDF. Solid black outline is the Weyburn field. Modified from Khan and Rostron, 2005.
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Figure 4: Modelled CO2 migration pathways and distances after 100,000 and 630,000 years in the Mississippian Aquifer. Weyburn field outline is shown in black. Colors are the observed salinity distribution. After Riding and Rochelle, 2009 modified from Audigane and LeNindre, 2004.