| Title | Optimization of Water and Two-Phase Components in the Openhole Section for Extraction Strategy in Leyte Geothermal Production Field |
|---|---|
| Authors | Rowena N. ABAPO, Jaime Jemuel C. AUSTRIA, Francis Xavier M. STA. ANA |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | peripheral, two-phase, liquid-dominated, steam-dominated, extraction, openhole |
| Abstract | The Tongonan or Leyte Geothermal Production Field (LGPF) is one of the larger liquid-dominated reservoirs in the world; however with continuous extraction since commissioning in 1983 and expansion in 1996, reservoir pressures declined that led to depression of the water level in the reservoir, most particularly in the central sections of the production field. Most of the wells in the central section of the fields have become two-phase or steam-dominated, while near the periphery of the field, the wells mostly remain liquid-dominated. One of management strategies to sustain steam supply to power plants was deep drilling of make-up wells drilled deeper towards the periphery of the reservoir to distribute the mass extraction and allow recovery in the drawn down central portion of the field. The additional data provided by the new wells drilled have supplemented our evaluation of the reservoir, particularly the contrasting results in terms of output produced among these peripheral wells. This has led us to investigate the different parameters (permeability, physical and chemical data) which could have affected the performance of the new wells. Preliminary evaluation showed that the major difference is the discharge enthalpy of the wells, which depends on the contribution of the two-phase and water components in the reservoir. In this study, wells with high mass flows having medium enthalpy are able to produce higher output compared to wells with low enthalpy. The result of this study is being incorporated into the assessment of the well design where production casing shoe (PCS) setting depth takes into account balanced contribution of the two-phase and water components in the openhole section for optimum extraction. This was also applied on the preliminary prediction of the likely output of a new well based on the outputs of offset wells with comparable percentage of openhole section above water level. Amongst others, well performance may still vary depending on the structures, reservoir temperature and pressure, and fluid chemistry of the reservoir where the well is drilled. |