Quantifying the Production of the Miravalles Geothermal Field According to the Evolution of the Productivity Characteristics and the Increasing in Installed Capacity

Abstract

Before the commissioning of the Miravalles Geothermal Field, the calculation of the amount of steam available for each well and the whole field based on the original output curves data was complicated. A way of making the procedure easier and automating the process of calculating mass flow rates and storing the results in spreadsheets was to develop software specially designed for those purposes.
As the installed generation capacity has increased and the behavior of the geothermal reservoir evolves, the calculation software should evolve too. After 15 years of continuous production the changing field characteristics forced a change in the way the calculations were made. The current parameters of the output curve were modified in order to reconcile the differences between the accuracy of the venturis measurements and the calculated steam by the output curves calculation. A new parameter called “percentage of opening” is defined based on the throttling of the side valve of the production well and is used instead of the wellhead pressure. The output curve is now redefined as the “evaluation curve”. All the changes performed in the calculation software are described in the present paper.