@article{WenzlaffWinterleitnerSchutz2019,
  author    = {Wenzlaff, Christian and Winterleitner, Gerd and Schutz, Felina},
  title     = {Controlling parameters of a mono-well high-temperature aquifer thermal energy storage in porous media, northern Oman},
  series = {Petroleum geoscience},
  volume    = {25},
  journal   = {Petroleum geoscience},
  number    = {3},
  publisher = {Geological Soc. Publ. House},
  address   = {Bath},
  issn      = {1354-0793},
  doi       = {10.1144/petgeo2018-104},
  pages     = {337 -- 349},
  year      = {2019},
  abstract  = {Aquifer thermal energy storage (ATES) as a complement to fluctuating renewable energy systems is a reliable technology to guarantee continuous energy supply for heating and air conditioning. We investigated a high-temperature (HT) mono-well system (c. 100 degrees C), where the well screens are separated vertically within the aquifer, as an alternative to conventional doublet ATES systems for an underground storage in northern Oman. We analysed the impact of thermal inference between injection and extraction well screens on the heat recovery factor (HRF) in order to define the optimal screento-screen distance for best possible systems efficiency. Two controlling interference parameters were considered: the vertical screen-to-screen distance and aquifer heterogeneities. The sensitivity study shows that with decreasing screen-to-screen distances, thermal interference increases storage performance. A turning point is reached if the screen distance is too close, causing either water breakthrough or negative thermal interference between the screens. Our simulations show that a combined heat plume with spherical geometry results in the highest heat recovery factors due to the lowest surface area to volume ratios. Thick aquifers for mono-well HT-ATES are thus not mandatory Our study shows that a HT-ATES mono-well system is a feasible storage design with high heat recovery factors for continuous cooling or heating purposes.},
  language  = {en}
}
@article{WinterleitnerSchuetzWenzlaffetal.2018,
  author    = {Winterleitner, Gerd and Sch{\"u}tz, F. and Wenzlaff, Christian and Huenges, Ernst},
  title     = {The impact of reservoir heterogeneities on High-Temperature aquifer thermal energy storage systems},
  series = {Geothermics : an international journal of geothermal research and its applications},
  volume    = {74},
  journal   = {Geothermics : an international journal of geothermal research and its applications},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0375-6505},
  doi       = {10.1016/j.geothermics.2018.02.005},
  pages     = {150 -- 162},
  year      = {2018},
  abstract  = {We conducted a geoscientific feasibility study for the development of a high-temperature thermal aquifer energy storage system (HT-ATES) outside the capital of Muscat, northern Oman. The aquifer storage is part of a solar geothermal cooling project for the sustainable and continuous cooling of office buildings. The main concept is that excess solar energy will be stored in the subsurface through hot water injection and subsequently utilised as auxiliary energy source during peak demand times. The characterisation of aquifer heterogeneities is thus essential to predict subsurface thermal heat plume development and recovery efficiency of the storage system. We considered two aquifer systems as potential storage horizons, (i) a clastic-dominated alluvial fan system where individual channel systems in combination with diagenetic alterations constitute the main heterogeneities and (ii) a carbonate-dominated system represented by a homogenous layer-cake architecture. The feasibility study included a multidisciplinary approach from initial field work, geocellular reservoir modelling to finite element fluid flow and thermal modelling. Our results show that for the HT-ATES system, with a high frequency of injection and production cycles, heat loss mainly occurs due to heterogeneities in the permeability field of the aquifer in combination with buoyancy driven vertical fluid flow. An impermeable cap-rock is needed to keep the heat plume in place. Conductive heat loss is a minor issue. Highly complex heat plume geometries are apparent in the clastic channel system and ATES well planning is challenging due to the complex and interconnected high permeable channels. The carbonate sequence shows uniform plume geometries due to the layer cake architecture of the system and is tentatively more suitable for ATES development. Based on our findings we propose the general concept of HT-ATES traps, incorporating and building on expertise and knowledge from petroleum and reservoir geology regarding reservoir rocks and suitable trap\&seal geometries. The concept can be used as guideline for future high-temperature aquifer storage exploration and development.},
  language  = {en}
}