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circuit shown in the lower left portion of the <br />figure. Electricity flows down the steel casing, <br />into the "pencil" connected to "good juice" in the <br />fracture, then into coke in the body of the fracture, <br />and finally out through a similar pathway on the <br />other side. With this approach successful <br />connections were made to both Electrofracs. The <br />final pipe-to-pipe resistances of EF1 and EF3 were <br />165 and 51.7 Ohms respectively. Based on its <br />lower resistance, EF3 was selected for a low- <br />temperature heating experiment. <br />lniecfinp III <br />Spueezina <br />Electrofrac Heating Circuit Schematic <br />Fig inn _ <br />M/ne R/b <br />I Insulated Coating on <br />Steel Pipes <br />Flexible Porous Piston Assembly <br />1 <br />"Pencil" Electrical Connection <br />t_ <br />rigure IL. squeezing the graphite "good juice" completes the Electrofrac circuit. <br />9. ELECTROFRAC POWER SHAKEDOWN <br />Before drilling instrumentation holes and <br />installing instruments for a low-temperature <br />experiment, Electrofrac EF3 was put through a <br />short power shakedown test. A voltage of 573 <br />VAC was applied to EF3 in an hour-long test <br />using a large variable transformer. The results of <br />this test are displayed in Figure 13. It is <br />noteworthy that the behavior of the fracture is <br />linear and that the current in one leg of the circuit <br />is larger than the other. This is indicative of a <br />connection through ground back to the <br />transformer. As a result of this observation the <br />heating power system for the low-temperature <br />experiment was designed to allow the voltage on <br />the two electrodes to float with respect to ground, <br />resulting in equal currents in the two legs. <br />Connection <br />Treatments <br />Coke•?pe ?/ecrro <br />d <br />c <br />? <br /> <br />12 <br /> <br />10 <br />N <br />d <br />a <br />E <br />a <br /> <br />C 6 <br /> <br />v <br />4 <br /> ? Amperage-OB9 <br /> ¦ <br />Amperage-OB4 <br />2 - 51.7 Ohm Line <br /> <br />0 <br />0 100 200 300 400 500 600 <br />Voltage, volts <br />Figure 13. Results of Electrofrac power shakedown test. <br />10. EXPERIMENT INSTRUMENTATION <br />Instrumentation holes for the low-temperature <br />heating experiment at EF3 are shown in Figure 14. <br />Most of the instrumentation measures temperature. <br />Sixteen holes roughly normal to the fracture <br />contain 21 thermocouples each to capture <br />29th oil Shale Symposium Page 9 of 13 October 19-23, 2009