New Challenges in casing design for deep geothermal well

Abstract

The new challenges in drilling deeper geothermal wells in the Cerro Prieto field, Baja California, Mexico, force the different areas to reengineer the selection of the casing settling depth with a new well structure, by incorporating a contingency casing, a new diameter using an integral connection. This configuration is planned to isolate areas that cause cross-flow contribution of water with different temperatures, causing problems of hole instability that directly increase operative time and drilling costs.

This solution consists of isolating the problematic area, maintaining the same completion clearance of the well. The design incorporates the corresponding adjustments due to the phenomenon of thermal degradation of materials, which causes a reduction of the pipe’s yield strength, and as a consequence, a direct reduction in the mechanical properties of the materials; this occurs under dynamic conditions during the steam production, mainly on the production casing. In addition, an adequate material selection to resist corrosion by CO2 is required, this phenomenon is a given during steam production, for instance, these materials have been successfully tested in the laboratory and in the field