In golf, a great caddie helps tune a professional golfer's performance, matching their skill, choice of club and type of swing to the course and weather conditions.
A recent analysis of drilling records from the Frontier Observatory for Research in Geothermal Energy by Sandia National Laboratories researchers aims to provide this level of guidance to the art of selecting the right drill bit for geothermal well drilling, based on location and depth, to reduce drilling costs. FORGE is a Department of Energy-funded field laboratory in southwestern Utah, dedicated to testing geothermal technologies to reduce risks and accelerate commercial viability.
Geothermal power plants offer the advantage of providing clean electricity all-day everyday regardless of weather conditions, thus balancing intermittent renewable energy sources such as solar panels and wind farms. However, the high startup costs for finding suitable locations and drilling the necessary wells have hindered commercial development. The FORGE project, alongside the Sandia analysis, aims to improve drill bit performance in the challenging conditions of geothermal sites and reduce drilling costs.
"At the FORGE site, a number of wells were drilled to depths of approximately 10,000 feet, and they were largely drilled by polycrystalline diamond compact bits," said David Raymond, a Sandia mechanical engineer and leader of the analysis. "This is one of the largest applications of diamond bits for geothermal drilling in their 40-year history. We produced a compendium of all the drill bits used and how they performed."
The Sandia research team, led by Raymond, analyzed drill rig data from the most recent wells drilled at the FORGE site, looking at the response data and post-operation photos of each polycrystalline diamond compact bit. The results of this analysis were recently shared with the geothermal community. Polycrystalline diamond compact bits have proven to be more cost effective than roller bits for oil and gas drilling, this compendium could help do the same for geothermal drilling.
Analysis for better bits
At the University of Utah-managed FORGE site, four wells were drilled for injection, production and monitoring, primarily using polycrystalline diamond compact bits. These bits use the strength of lab-made diamonds in the form of disc-shaped cutters. Many of these cutters are embedded into the bit in a specific arrangement designed to best cut the rock. The industrial diamonds in these bits are tiny, grown in a lab for strength rather than aesthetics.
