Casing setting depth and design of production well in water-dominated geothermal system with 330 °C reservoir temperature

Abstract

Casing, with its two main elements: casing setting depth and casing design, is one of well barrier elements playing a significant role for geothermal well integrity. All of the internal and external loads experienced by the casing from its installation into the well until the end phase of well, called plug and abandonment, have to be calculated precisely. Moreover, the casing must be able to withstand the geothermal environment: high-temperature, high-strength rock, highly-fractured formation, corrosive fluid, and under-saturated pressure. Therefore, the casing specification can be properly determined based on the technical and economic considerations to achieve a high quality of well integrity and endurance starting from drilling and completion, production, maintenance (well intervention, and workover), conversion into an injection well or vice-versa, and plug and abandon (P&A).This research study discussed the production well HCE29 in Dieng Field, Indonesia, characterized by a water-dominated geothermal system with temperature of up to 330 °C and pressure of up to 19.4 MPa. After the well was drilled and completed, the casing failure was identified. This study consisted of analysis and re-calculation of this well at the phases of drilling, completion, production, and maintenance to improve the casing setting depth and design method. The results show that the casing failure occurred in this well. In addition, this study improved the Philippines’ method used for re-calculation of casing setting depth and the casing design evaluation method.