Comprehensive Production Casing Stress Evaluation in Directional Geothermal Well

Abstract

Casing stress is calculated in tension condition that is as equal as normal weight of the casing plus drag and slip when casing is running. In directional well, vertical normal weight of the casing is reduced because of the fact that some weight of the casing is handled by the formation in the slant section. However, casing stress increase in directional well that is caused by additional drag force on the casing. Another stress that is added in directional well is bending stress. It is caused by dog leg of the well that affects the casing where it is increasing below kick of point. Dog leg is causing compression and tension stress around the casing. Compression stress usually is neglected from bending stress calculation. Compression stress should be considered in bending stress calculation because it is important to analyze casing failure. Moreover, thermal analysis must be conducted because geothermal well has wellbore temperature above 100°C. This study will focus on calculating casing stress based on drag, dog leg, and thermal analysis in geothermal directional well to prevent casing failure especially in geothermal Indonesia’s field. Mostly, geothermal well is directional well because the reservoir is located below restricted area. The comprehensive casing stress calculation is developed and verified by using Field X data. Therefore, casing design in Field X can be optimized and applied for further usage.