Geothermal reservoir modeling including statistical, lumped, distributed and multiphase models
Reservoir model simulations have become an important tool in the planning and management of geothermal reservoirs, and are essential in ensuring the sustainability of the resources.
The numerical modeling of a geothermal reservoir can typically be separated into three distinctive phases of development and operation.  These phases are separated into model establishment, application and management.  The tools applied in the modeling efforts are chosen to suit the problem at hand, for the most reliable and effective results.  The Mannvit team has extensive experience with a great variety of modeling approaches, including statistical, lumped, distributed and multi-phase models. 

Monte Carlo statistical simulations can be helpful tools in the early stage volumetric estimates of a geothermal reservoir.  With further data established at a site, time dependent lumped models can be established, without spatial variation.  Distributed models are typically applied once enough data have been gathered for more extensive modeling approaches with temporal and spatial variations.  This will, for example, allow for simulations of temperature and pressure changes within the reservoir, siting of injection wells and future predictions of pressure decline.  Mannvit team member  Vatnaskil has developed AQUA3D which has proven to be successful in such modeling efforts.  In two-phase reservoirs the modeling approach may require the establishment of a TOUGH2/iTOUGH2 model, which is a general-purpose numerical simulation program for multi-phase fluid and heat flow in porous and fractured media. 
 
Project example
In 2008, the Mannvit team member Vatnaskil developed a geothermal reservoir model for the National Power Company of Iceland (Landsvirkjun) of the Theistareykir geothermal area in Northeast Iceland.  The work involved setting up a numerical model using the TOUGH2 simulation package and calibrated against production and enthalpy histories, as well as estimated natural state temperature and pressure profiles using the iTOUGH2 tool.