Silica Deposition in High Enthalpy Well: A Phenomenon Encountered in Palinpinon Geothermal Field, Philippines

Abstract

Mineral deposition along the wellbore can cause output decline of geothermal production wells. A well in Palinpinon-2 sector was initially discharging two-phase fluid, however, due to pressure drawdown, it eventually dried up in 2010. A steep decline in output was observed in the well and the suspected cause is wellbore deposition based on downhole survey. Mineral deposits composed mostly of amorphous silica were also present along the branchline during the inspection of the two-phase line in 2012. Geochemical modelling and evaluation were conducted and the results showed that a transient increase in the brine loading of the reinjection (RI) well from a nearby sector is the likely source of the silica rich fluid that flashed and deposited as it reaches the wellbore. Previous naphthalene disulfonate (NDS) tracer study conducted also confirmed the reservoir connection between well and the reinjection (RI) well.