| Abstract |
At the Miravalles geothermal field there are wells that produce acid fluids, which have been successfully utilized by treating the acidity using a neutralization system. The system continuously adds sodium hydroxide (NaOH) through a capillary tubing string that reaches the production zones of the wells, to neutralize the acid fluids. Conditions inside the wells can lead to failure of the capillary tubing, causing the neutralization system to operate improperly. This situation is very difficult to detect from the surface, unless an iron meter is installed as part of the neutralization system. When the capillary tubing breaks, fluids are neutralized in only part of the wellbore, causing corrosion inside the well. An iron meter can detect, under these conditions, the amount of iron that enters the brine, which serves as an indirect signal that corrosion has increased due to the broken capillary tubing, even when pH readings are within the normal operating range. The need to have an indirect indicator of a capillary tubing failure has led to the installation of iron meters as a part of the neutralization systems. The first digital equipment and sampling methods used did not work well. Field tests, analysis of the results, modifications and corrections to the sampler have resulted in important improvements in the instrumentation. A description of the iron meters utilized in the geothermal wells and the improvements made in the sampling methods are described in this document. |