| Title | Update on the Modelling of the Rotokawa Geothermal System: 2010 - 2014 |
|---|---|
| Authors | Dario HERNANDEZ, Jonathon CLEARWATER, John BURNELL, Peter FRANZ, Lutfhie AZWAR, Andrew MARSH |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Rotokawa, modelling, tough2, simulation |
| Abstract | The Rotokawa geothermal field is located in the Taupo Volcanic Zone, New Zealand. In 1997 an initial 29 MW Ormat power station was commissioned on the field and in 2010 a second 132 MW triple flash plant was added. During 2011, to facilitate optimal field management, a large scale (131 km2) numerical model using TOUGH2 was developed in collaboration between Industrial Research Limited and the Mighty River Power Geoscience Department The numerical model was based on an updated conceptual model and it was calibrated to match the thermodynamic conditions found in the natural state and the evolution during the production period, including the gravity changes. Since 2012 this model has been used in-house by Mighty River Power engineers for predicting make-up well requirements, environmental consent, testing theories about field behaviour and field management. A number of capabilities have been added to the modelling software during the modelling efforts. These include permeability barriers in TOUGH2 to simulate the high degree of heterogeneity in reservoir permeability and the associated pressure compartments, and functionality to enable the integration of wellbore and plant models. The Rotokawa numerical model is capable of simulating fluid take and injection requirements with automatic switching on of make-ups wells and throttling as the reservoir conditions change, making it an effective tool for reservoir management. This paper presents the results from the collaborative effort undertaken in the last four years emphasizing the integration of field data for the coupling of the wellbore and plant models, resulting in an improvement in the matching of pressure and enthalpy evolution. |