Here are the stages of geothermal development in the Philippines for a 40 to 100 MW geothermal project:
- Project definition and reconnaissance evaluation. This phase involves collecting information from previous geological, geochemical and geophysical studies made in the area with particular emphasis on mapping of young volcanic activity, thermal manifestations such hot springs, steam jets, groundwater boreholes and even known traditional utilization of geothermal resources.
- Detailed exploration – During this phase, detailed mapping of geothermal manifestations and detailed study of geological controls on the distribution of the geothermal resource are very important in developing the conceptual model of the geothermal system. Target structures for drilling are identified after consolidation of the interpreted results of the detailed geological, geochemical and geophysical investigations.
- Exploratory drilling and delineation – Two or three exploratory wells, 2500 to 3000 meters deep, are prioritized based on the conceptual model of the reservoir.
- Resource analysis and assessment of development potential – The final output of this phase is a complete technical and financial feasibility study that can be used to solicit funding from financiers for the development of the project.
- Field development – This phase involves production and reinjection drilling, detailed design, procurement and construction of the fluid collection and reinjection system (FCRS).
- Steam production and resource management – The satisfactory and efficient operation and maintenance of the geothermal production facility and the power plant after the completion and commissioning tests will be the key to the fulfillment of contractual commitments and the realization of cash flows from the project over the long term. In the process of exploitation, the behaviour of each individual well is closely monitored.
- Shutdown and abandonment – As the geothermal reservoir is exploited, it is expected to decline in pressure and steam output over the long term. In addition, the surface equipment may start failing to an extent that it is no longer economical to run the plant, and as such, require to be shut down and abandoned. But this stage seems to be a long, long way into the future for as long as proper resource management is implemented. The first 110 MW geothermal power plants in Tiwi and Makban are already 26 years old. The 112.5 MW Tongonan I and 112.5 MW Palinpinon I are already 23 years old. These geothermal fields and power plants are predicted to last another 25 years.
Here is a time table when developing a 40 – 100 MW geothermal project in the Philippines: