Slimhole well casing design for high-temperature geothermal exploration and reservoir assessment.
Michał Kruszewski, Sverrir Thorhallsson, Mohsen Assadi, Tomasz Śliwa
Vol. 34, no. 2 (2017), s. 465-492, [1]
It is anticipated that utilization of geothermal resources for renewable energy production will continue to grow globally. Since cost of drilling and well construction constitutes a considerable share of the total cost of the geothermal installations, development and evaluation of low-cost alternatives is crucial for expansion of this industry. This paper describes slimhole casing design for geothermal exploration wells, as an alternative for reduced cost and improved environmental performance. The main goal of the paper is to contribute to cost effective casing design program that satisfies severe reservoir conditions of geothermal wells. A case study is presented for casing design for a 2000 m deep vertical well with water level at 200 m, where the New Zealand Code of Practice has been applied. The “worst case scenario”, i.e. when temperature and pressure follow the boiling point depth curve (BPD), has been considered as base case for the casing design, when drilling in a high-temperature geothermal area. Alternative methods are also presented for determining the minimum casing setting depths and the results are compared. Pressure and temperature conditions inside the well were established using X-steam program, an Excel add-in, and the final results, establishing loading criteria that the casing has to withstand i.e.: burst, collapse and tension/compression are presented.