Injection well KA44 at the Kawerau Geothermal Field was acidised with 10% HCOOH (Formic Acid) / 5% HF (Hydroflouric Acid) in April 2019. This work, along with a previous acid stimulation of injection well PK4a in 2017, was conducted to improve the well’s injection capacity while also providing information to a wider investigation to address silica management at Mercury’s geothermal fields. Several of Mercury’s geothermal fields operate with silica saturation indices in excess of 1.7, as described in Addison et al. (2015). Despite the use of various plant designs to reduce the risk of silica polymerization and deposition, injection well decline continues to be an issue. KA44 was selected as a candidate well for acid stimulation, as it is shown through reactive modelling and laboratory testing that the injection decline is a result of silica scaling in the near wellbore formation. KA44 was acidised previously in 2010 using 10% HCl (Hydrochloric acid)/ 5% HF, however the initial improvement in injectivity was short lived. The 2019 KA44 acidisation program was optimised based on lessons learned from the previous stimulation in 2010 and from the acid stimulation of PK4a in 2017 in order to improve the chance of success. The results of this acid stimulation of KA44 are compared against the first acid stimulation of this well in 2010, as well the results of the acid stimulation of PK4a in 2017.

Press the Back button in your browser, or search again.

Copyright 2020, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.