| Title | Performance Evaluation of Deepened Wells 420DA and 517DA in the Leyte Geothermal Production Field, Philippines |
|---|---|
| Authors | Rowena ABAPO, Marie Hazel COLO, Romeo ANDRINO, Edwin ALCOBER |
| Year | 2013 |
| Conference | Stanford Geothermal Workshop |
| Keywords | LGPF, Upper Mahiao, Malitbog, enthalpy, acidizing |
| Abstract | The Leyte Geothermal Production Field (LGPF), located in central eastern Philippines, is a key contributor of geothermal power since its operation in 1997. To enhance steam field production, two shallow wells, 420D and 517, were drilled in 2004 with depths of 1200 m and 1700 m respectively. On completion, these wells were poised to meet the steam requirements of the power plants in LGPF contributing a combined output of 4 MWe. Well 420D has been producing since 2004 until it collapsed in June 2007 but was revived through vertical clearing discharge. When 420D reached minimal output in November 2010, well was evaluated for deepening with acidizing. This was implemented in May 2011 resulting to a gain of 8 MWe. Successful deepening of the initially high enthalpy well 420D was achieved by tapping both the shallow two-phase and deep liquid zones of the reservoir resulting to a medium enthalpy discharge. The well also intersected more the Mahiao East Fault and a new structure Litid South Fault in the openhole section providing additional production. On the other hand, 517 was evaluated for re-entry/deepening in July 2011 to increase production and clear the mineral deposits, although output has been stable since 2008. The minimal increase of 1.6 MWe in the post-deepening output of 517DA was expected due to the shallower than programmed total depth cleared and the inability to maximize the target East Fault Line. The LGPF experience in wells 420DA and 517DA highlighted the importance of the productive structures to be intersected, the well’s downhole temperature, enthalpy range, setting depth of the production casing shoe and the length of the openhole section to ensure the improved performance of shallow wells upon deepening. Tapping both the shallow two-phase and deep liquid zones of the reservoir resulting to a medium enthalpy discharge has contributed to the improved performance of the deepened wells. |