ABSTRACT

Geothermal energy is a strategic renewable resource for Indonesia, yet Well XY in Field X is currently facing a critical problem of significant production rate decline. This research aims to analyze the current decline trends and forecast the future production rates of Well XY to ensure the sustainability and efficiency of geothermal power plant operations. The study utilizes a quantitative descriptive method, employing the Spivey Decline Curve Analysis (DCA) approach and the Gauss-Jordan reduction method for data regression. Results indicate that the decline is primarily influenced by operational steam losses at the rock muffler and cooling tower, which disrupt the production cycle. The analysis calculated a loss rate parameter (b) of 0.053, with the regression model demonstrating high accuracy against actual historical data. Forecasting suggests that production will continue to decline, reaching 11.23 t/h by December 2025 if no technical interventions are implemented. In conclusion, the Spivey method provides a reliable projection for predicting well performance, highlighting the necessity of operational adjustments to prevent steam supply shortages.