Praxisseminar - Reservoirtechnologien

Prof. Dr. Peter E. Malin

Institute of Earth Science and Engineering, University of Auckland

Auckland, New Zealand

This seminar briefly introduces the Institute of Earth Science and Engineering’s research themes, operation, and staff.  The discussion then turns to IESE’s efforts to profile and model crustal reservoirs – especially geothermal ones – and thereby produce meaningful “resource index maps” for scientific and practical purposes.      

The idea of a resource index map comes about from the complicated, multidimensionality of fluid-bearing rock and fluid flow in time and space.  Such a map needs to represent more than a single physical and/or chemical characteristic in a 3-D volume – characteristics that might also be changing with time. 

In the case of reservoirs, the dimensions are several fold, including porosity, permeability, and fluid composition.  These are intimately mixed up with the erratic fracture-networks.  The combination of these factors determines, for example, the balances between advective, conductive, and convective heat transfer.  Providing a theory for the complex fluid/rock interactions will yield methods for observing these combinations and understanding their distributions, which is what index mapping is all about. 

In the practical sense, resource index mapping for geothermal reservoirs is about finding highly productive zones for drilling.  The extra dimensions here are temperature, porosity, permeability, chemistry and fracture density. Any place with high temperatures, plenty of porosity, good permeability, and relatively pure water would have a high resource index. 

The members of the Institute of Earth Science and Engineering are working toward such maps, progress in which is reported on in this presentation.  Seismic and electromagnetic profiling and interpretation methods are being used to find permeable fracture zones with abundant hydrothermal waters.  The manner in which these vary is being modeled with ideas from critical phenomena physics.  The models are being applied to numerical representations of fluid flow. 

The practical value of these efforts is being demonstrated by drilling success in Kenya, Iceland, and the US.

Finally resource, EGS and seismicity aspects from the Basel project will be discussed.