Chemicals Systems Used in the Exploitation at the Miravalles Geothermal Field, Costa Rica: Calcium Carbonate Inhibition Systems for Neutral Wells and Neutralization Systems for Acid Wells

Abstract

The reservoir fluids are over-saturated with respect to calcium carbonate at the flashing zone in most of the Geothermal Field. Without a calcium carbonate inhibition system, the mineral is deposited on the production casing of the well, lost flow (and energy) in few time is a fact. The implementation of the inhibition system has been successfully applied since 1994. Therefore production problems by obstruction and mechanical cleanouts are minimized by optimizing the process (like an appropriate dose). On the other hand, has managed to optimize the products used, both in quality and price. Furthermore, about 5 wells have acidic fluids with a pH value between 2.3 to 3.2. However, two of them are in production today (PGM-07 since 2001 and PGM-02 since 2006) by the neutralization system implementation, which has been used successfully, allowing the use of the resource to generate 10 MW in plants. There are 22 systems for inhibition of calcium carbonate scale and 3 neutralization systems (two of them on line). Some economic aspects are discussed under the appropriate sections