Geomechanical Modeling for Thermal Spallation Drilling

Abstract

Wells for Engineered Geothermal Systems (EGS) typically occur in conditions presenting significant challenges for conventional rotary and percussive drilling technologies: granitic rocks that reduce drilling speeds and cause substantial equipment wear. Thermal spallation drilling, in which rock is fragmented by high temperature rather than mechanical means, offers a potential solution to these problems. However, much of the knowledge surrounding this drilling technique is empirical - based on laboratory experiments that may or may not represent field conditions. This paper outlines a new numerical modeling effort investigating the grain-scale processes governing thermal spallation drilling. Several factors affect spall production at the mesoscale, including grain size and size distribution, surface temperatures and material heterogeneity. To investigate the relative influence of these factors, we have conducted a series of simulations using GEODYN - a parallel Eulerian solid and fluid dynamics code. In this paper, we describe a two-dimensional model used to simulate the grain-scale processes and present preliminary results from this modeling effort.

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Additional Info

DOE Project Name: Geomechanical Modeling for Thermal Spallation Drilling
DOE Project Number: LLNL FY11 AOP2
DOE Project Lead: Greg Stillman
Last Updated: over a year ago
Aug
2011
Data from August, 2011
Submitted Feb 13, 2013

Contact

Lawrence Livermore National Laboratory


Status

Publicly accessible License 

Authors

Stuart D.C. Walsh
Lawrence Livermore National Laboratory
Ilya Lomov
Lawrence Livermore National Laboratory
Jeffery J. Roberts
Lawrence Livermore National Laboratory

Keywords

geothermal, geomechanical modeling, thermal spallation drilling, engineered geothermal systems, egs, geodyn, numerical modeling

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