MODELING OF A EUROPEAN PROTOTYPE HDR RESERVOIR

The European Hot Dry Rock Geothermal Energy Project, located in the Rh ine graben at Soultz-sous-Forets, Alsace, France, is entering a new ph ase in its development. Over the next few years the existing HDR syste m will be developed to form an operational Scientific Prototype HDR Sy stem. This paper provides an introduction to the collaborative reservo ir modelling studies undertaken as part of the European Programme. In particular the paper addresses the general methodology adopted in the reservoir design process and focuses on one of the preliminary objecti ves of the study, assessment of the minimum HDR doublet separation req uired to meet the thermal performance objectives during circulation. T wo ''preliminary reservoir designs'' are adopted as starting points fo r the study, the first based on exploitation of large scale planar fra ctures, the second on the development of a modular (multi-cell) system based on 3 cells supporting 5l/s production each. Estimates were obta ined using models based on both idealised geometry and empirical obser vations of reservoir circulation at the Camborne School of Mines (CSM) HDR project. The results indicate that a wellbore separation of aroun d 400m would be required for the multi-cell system to achieve the requ ired thermal performance of 10% thermal drawdown, or less, during 10 y ears circulation at 15l/s production. Whereas, the wellbore separation required for the single fracture design would be in excess of 650m.