G Geothermal well drilling technology adopts many oil and gas well drilling technologies. Geothermal wells are usually drilled with a larger diameter, deeper, and intended for a longer production time than oil and gas wells. Good planning is the key to success in casing and liner installation operations. In geothermal drilling, one of the problems faced is that the liner used cannot withstand the load of the programmed circuit for the production process, and the high temperature of the formation. Field O GEB-10 well is a geothermal field, so the selection of appropriate grade (material) casing is needed to be able to withstand formation temperatures. Evaluation of the installation of the liner to determine whether the liner has buckling or not, and know the steps to prevent buckling. The calculation used to determine the type of casing grade is by calculating the Compressive load, buckling limit and Thermal Elongation. In the calculation of the liner 10 3/4 "with a length of 917 m, the compressive load results are 125994.37 lbs and the buckling limit is 71402.48 lbs and thermal elongation is 2.27 m, while on the liner 8 5/8" the length of the route is 1195 m obtained the results of a compressive load of 97298.45 lbs and the buckling limit of 38515.1 lbs and thermal elongation of 2.96 m. From the calculations on the 10 3/4 "and 8 5/8" liners, there is an indication of helical buckling so it must be anticipated by reducing the length of the liner to 537 m for the 10 3/4 and 444 m for the 8 5/8 liner, or by replacing higher grade liner.