Complex fluid flow revealed by monitoring CO2 injection in a fluvial formation

At Cranfield, Mississippi, United States, a large‐scale carbon dioxide (CO2) injection through an injection well (∼3,080 m deep) was continuously monitored using U‐tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which c...

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Bibliographic Details
Published in:Journal of Geophysical Research: Solid Earth 2012-03, Vol.117 (B3), p.n/a
Main Authors: Lu, Jiemin, Cook, Paul J., Hosseini, Seyyed A., Yang, Changbing, Romanak, Katherine D., Zhang, Tongwei, Freifeld, Barry M., Smyth, Rebecca C., Zeng, Hongliu, Hovorka, Susan D.
Format: Article
Language:English
Subjects:
CO2 injection
Earth sciences
Earth, ocean, space
Exact sciences and technology
flow path
flow simulation
fluid flow
Geomorphology
Geophysics
Hydrology
Mineralogy
Petrology
Physical properties
reservoir fluid composition
Scientific apparatus & instruments
Tuscaloosa Formation
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Summary:At Cranfield, Mississippi, United States, a large‐scale carbon dioxide (CO2) injection through an injection well (∼3,080 m deep) was continuously monitored using U‐tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which consists of amalgamated fluvial point‐bar and channel‐fill deposits, presents an interesting environment for studying fluid flow in heterogeneous formations. Continual fluid sampling was carried out during the first month of CO2 injection. Two subsequent tracer tests using sulfur hexafluoride (SF6) and krypton were conducted at different injection rates to measure flow velocity change. The field observations showed significant heterogeneity of fluid flow and for the first time clearly demonstrated that fluid flow evolved with time and injection rate. It was found the wells were connected through numerous, separate flow pathways. CO2 flowed through an increasing fraction of the reservoir and sweep efficiency improved with time. The field study also first documented in situ component exchange between brine and gas phases during CO2 injection. It was found that CH4 degassed from brine and is enriched along the gas–water contact. Multiple injectate flow fronts with high CH4 concentration arrived at different times and led to gas composition fluctuations in the observation wells. The findings provide valuable insights into heterogeneous multiphase flow in rock formations and show that conventional geological models and static fluid flow simulations are unable to fully describe the heterogeneous and dynamic flow during fluid injection. Key Points We continually monitored CO2 injection in a fluvial reservoir Fluid flow showed tremendous heterogeneity and evolved with time Sweep efficiency increased with time
ISSN:0148-0227
2169-9313
2156-2202
2169-9356
DOI:10.1029/2011JB008939