Corrosion, Scaling and Material Selection in Deep Geothermal Wells – Application to IDDP-2

Abstract

In order to make the world’s energy consumption sustainable there is a need for reducing emissions of CO2 and to shift towards renewable energy sources. Geothermal energy has a large potential in certain parts of the world. One example is Iceland, where the reservoir in IDDP-2 is around 427°C and 340 bar at a final well depth of 4650 m. This makes it attractive as a geothermal reservoir of high enthalpy supercritical water with the potential for conversion of large amounts of high temperature deep geothermal energy. Production from the IDDP-2 is scheduled to start in 2019, and hence the fluid composition is not known. Using available data for nearby wells, and in particular IDDP-1, an estimate can still be made. A combination of high temperature and pressure, the presence of corrosive agents (such as HCl and H2S), a low pH and reducing conditions gives rise to challenges related to material selections. This paper summarizes part of a desktop case study that addresses corrosion and scaling issues for conditions relevant for the IDDP-2 geothermal well. The reservoir and well data are based on temperature measurements inside the well and assumptions on a hydrostatic reservoir. The total depth of the well is 4650 meters. Based on this a model is set up for temperature and pressure profile along the well. Knowledge gaps, such as lacking solubility data and corrosion rates at supercritical conditions are pointed out. Paper reproduced with permission from CORROSION/2019 Annual Conference and Exhibition. www.nace.org