Effect of Aquifer Heterogeneity, Brine Withdrawal, and Well-Completion Strategy on CO2 Injectivity in Shallow Saline Aquifer
- Olanrewaju Moshood Tiamiyu (Missouri U of Science & Tech) | Runar Nygaard (Missouri U of Science & Tech) | Baojun Bai (Chevron)
- Document ID
- Society of Petroleum Engineers
- SPE International Conference on CO2 Capture, Storage, and Utilization, 10-12 November, New Orleans, Louisiana, USA
- Publication Date
- Document Type
- Conference Paper
- 2010. Society of Petroleum Engineers
- 5.1.1 Exploration, Development, Structural Geology, 4.6 Natural Gas, 2.2.2 Perforating, 6.5.7 Climate Change, 5.4 Enhanced Recovery, 6.5.1 Air Emissions, 6.5.3 Waste Management, 5.8.3 Coal Seam Gas, 2 Well Completion, 5.5 Reservoir Simulation, 5.4.2 Gas Injection Methods, 5.10.1 CO2 Capture and Sequestration
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The most promising near term solution to reduce CO2 emissions is to capture the CO2 produced from coal and gas fired power plants and inject it into deeply buried saline aquifers. However a large amount of these plants are far away from deep sedimentary basins and therefore alternative solutions have to be sought. Detailed computer simulation, using compositional numerical model software CMG-GEMGHG, was used to study the effects of aquifer anisotropy (heterogeneity), well completion technique (perforation and well orientation), brine production and injection rates on CO2 injectivity, and capability to retain and store reasonably large amount of CO2 for an extended period of time. The objective of this study is to find the optimal combination of operational parameters (injection rates, well completion techniques and brine withdrawal strategy), and how the interplay of these parameters with aquifer anisotropy (heterogeneity) affects, and can be manipulated to optimally harness CO2 storage potential and leakage risk mitigation in shallow saline aquifers.
Injected CO2 exists in three main forms in the aquifer, supercritical, dissolved and aqueous forms with amount depending largely on prevailing formation pressure and the depth of well placement. Without brine withdrawal, horizontal injector wells with the vertical sections closed have higher CO2 injectivity compared to vertical and deviated wells with bottom half perforated. With brine withdrawal more CO2 was injected and anisotropy (heterogeneity) (Kv/Kh ratio) has significant effect on CO2 injectivity, but well perforation and orientation has negligible effect, except for an extended (85 years) injection period when aquifer pressure has reached the maximum allowable. The impact of anisotropy (heterogeneity) on CO2 injectivity was observed to decrease with increase on injection rate for injection well placed in uppermost layers. This study shows CO2 sequestration in shallow saline aquifer has significant potential. Results from this study can potentially provide guideline for well completion technique, injection rate and brine withdrawal strategy, depending on aquifer properties, that can be applied in CO2 sequestration in shallow saline aquifer.
Global warming and its attendant consequences have become a major concern to the world. The primary source of this phenomenon has long been attributed to the burning of fossil fuel (automobile, gas and coal fired power plants), which results in the emission of excessive amount of CO2 into the atmosphere. One of the major sources of emission into the atmosphere is from the coal fired power plants. A potential solution to this particular source of CO2 emission is to capture the CO2 produced from these power plants and inject it into geological formations, namely depleted oil, gas and coalbed methane (CBM) reservoirs, and underground saline aquifer. The potential CO2 storage capacity of these geological formations in the Southeast Carbon Sequestration Partnership alone have been estimated to be 2,369.4 to 9,235.5 gigatonnes, with saline aquifers accounting for 95% of this storage capacity (Petrusak et al. 2009). The SECARB partnership comprises Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and east Texas. The Plains CO2 Reduction (PCOR) Partnership, comprising of regions in Canada (Alberta, British Columbia, Manitoba, Saskatchewan,) and United States (Iowa, Minnesota, Missouri, Montana, , Nebraska, North Dakota, South Dakota, Wisconsin, Wyoming), have also been estimated to have geologic CO2 storage potential of 242 billion tonnes; 91% of which is in the saline aquifers (UND-EERC, 2009). However for many states, including the State of Missouri, lies far away from the deep sedimentary basins and would likely be subject to the highest transportation costs for CO2 disposal. Therefore for many utility companies which are faced with the prospect of federal and state regulation of CO2 emissions, need to develop an effective, economical means to capture and sequester CO2 in the proximity of the power plants.
|File Size||3 MB||Number of Pages||15|