COMPUTER MODELLING OF MONTSERRAT GEOTHERMAL FIELD

Abstract

A geothermal field on the island of Montserrat is being investigated and considered for development. There have been various geoscientific studies and three wells have been drilled. Temperature profiles are available from two of them. From this information a conceptual model was developed and a computer model was set up. A fairly simple geological model was used with only four major formations and five major faults included.
The model covers an area of 7 km x 6 km and extends to a depth of 4000 m below sea level. An air/water equation of state is used so that the unsaturated vadose zone can be included. Part of the model extends under the ocean. The model contains ~16000 blocks (28 x 24 blocks in most layers, but fewer in the shallow layers that follow the topography and bathymetry).
A natural state model was first manually calibrated and then automated calibration with iTOUGH2 was used to further improve calibration. A good fit to the temperature profiles in Mon-1 and Mon-2 was achieved.