| Title | Improved Availability of 5MW Collapse-prone Mahanagdong-B Well in Leyte, Philippines, Since 2014 |
|---|---|
| Authors | Kay Kimberly L. KOBAYASHI, Lorena M. DACO-AG, Danilo B. DACILLO |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | collapse, peripheral, RI inflow, low-pressure operation, thermal recovery, improvement, enthalpy |
| Abstract | Mahanagdong Geothermal Field in Leyte, Philippines, is supplying steam to 2-unit Mahanagdong-A (120MW) and 1-unit Mahanagdong-B (60MW) operations. Mahanagdong-B production wells are also supplying to Mahanagdong-A via steam line interconnection (SLI) to augment its steam available. However, there were identified Mahanagdong-B wells that are prone to collapse resulting to decline in Mahanagdong steam availability. These wells are assessed to be affected by peripheral inflow and cold fluid injection (Peripheral/RI inflow) from the west which have led to thermal decline and collapsing of wells, thus not being able to attain the higher operating wellhead pressure (WHP) requirement. One well in Mahanagdong-B sector, was one of the recorded collapsing wells in 2014 caused by peripheral/RI inflow resulting to 5MW loss in Mahanagdong steam availability. Numerous well discharge attempts were conducted in 2014-2016 but all failed to sustain well discharge and was out of service since. Resource management initiatives and low-pressure operation projects were implemented in 2017-2018 to optimize steam generation. In 2018, the well was included in the Leyte cut-in and recovery program as one of the existing production wells that were out of service for years. The program aims to recover and cut-in all idle production wells using the available resources for additional steam supply to sustain the Mahanagdong 3-unit operation. The well was able to successfully discharge and sustained cut-in contributing additional 5MW since 2018. Well availability is observed to have improved and became more reliable after commissioning of the low-pressure operation and eliminated cold fluid injection in the west. Lowering the separation pressure allows the pressure of newly-recovered well to withstand the two-phase header pressure and continuously flow within the system and stabilized. On the other hand, elimination of RI cold fluid injection leads to thermal recovery and improvement of well enthalpy. |