Finite Element Modelling of a Novel Casing Protection for High Temperature Geothermal Wells

Abstract

Geothermal energy is widely used in Iceland from electricity generation in power plants to direct utilisation in greenhouses and swimming pools. Although the operational costs of utilising geothermal energy is low, the maintenance of geothermal wells can be costly. A novel casing protection, the Sacrificial Casing, could be used to decrease the maintenance costs of high temperature geothermal wells, as well as protecting them from corrosion and high loads due to constrained thermal expansion effects of the geothermal well environment. This paper investigates the advantages of using the sacrificial casing in high temperature geothermal wells by using finite element methods. Multiple axisymmetric 2D thermal and structural analyses were conducted using the programme ANSYS Mechanical. Pressure and temperature data from a geothermal well in Iceland (HE-61) was used to analyse and compare three different drilling and production scenarios with and without the sacrificial casing in the well. Materials with varying thermal conductivity, specific heat and density values are also analysed to compare the sacrificial casing s effects on temperature and stress distributions in each scenario.