A Cost-efficient Way to Produce a Geothermal Well

Approximately 70 % of the budget of a geothermal project is spent for the construction of the wells. Therefore, the aim of the Geothermal Energy and High Performance Drilling Research Program (gebo) is to reduce the costs for the production of power through geothermal energy. To minimize these drilling costs the drilling time and the time needed for the deployment of the casing have to be decreased as possible. The basic concept herein is to decrease the well diameter by creating a monobore well. Essential in accomplishing this is a special type of casing, structured from the folded tubulars for expandable casing applications featuring clover-like cross sections, expandable to a cylindrical form, when the casing is at its downhole position. This enables to increase the drilling speed and leads to less completion work.

The handling of these special tubulars with conventional manipulators is rather unfeasible. Therefore, a Casing-Running-Tool (CRT) was modeled in such way so as to be insertable from the upper end and grab the complex shape of the novel folded tubulars from the inside. This tool form provides minimum space requirements while at the same time allowing the tool to descend into the well.