Use of Practical Measurement Techniques in the Assessment of Rock Fragmentation Experiments

摘要

Rock fragmentation to form a suitable rubble bed for in situ oil shale retorting involves blasting the shale into or toward the confined volumes of previously created voids. With the high cost of site preparation (e.g., mining of access drifts and experiment rooms) for field experiments in oil shale, each test should be optimized. Appropriate measurements to improve the understanding of what occurred and why it is vital to both the assessment of the experiments and the development of numerical rock fragmentation models. Instrumentation techniques developed at Sandia National Laboratories have provided practical measurements of rock response during explosive fragmentation. Detonation-induced stress waves have been measured with stress gages and accelerometers. Measurements of rock motion over an extended time have been made with accelerometers mounted in ''cages'' of ground-matching grout, borehole extensometers, and photometrics. A special downhole data acquisition/recording system recently developed permits rock motion measurements at increased depths. These measurements have been extremely valuable both for assessment of the individual experiments and for correlation with model simulations of the blasts. 14 refs., 17 figs. (ERA citation 10:050904)