Geothermal Well Design – Casing and Wellhead

Abstract

The Geothermal well design process includes consideration of the objectives and purpose of the well, the subsurface conditions likely to be encountered during the drilling process, and the identification of required equipment, materials, and drilling procedures needed to ensure a satisfactory well completion and an acceptable well life.

The design steps which are necessary to drill and complete a deep geothermal well safely are:
• Subsurface rock and fluid conditions.
• Depths of casings and well completion.
• Casing specification and cementing materials and programmes
• Wellhead specification
• Drilling fluids, drill string assemblies
• The necessary drilling tools and equipment.

Perhaps the most critical aspects of these design steps is the selection of casings, casing specification, casing shoe depths, and how the well is completed. This paper reviews the casing and wellhead specification process.