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APPENDIX E <br />Outline for Recommended Full-Scale Monitoring System <br />Access and Settings of TRT Monitoring System <br />Technically, the only access for a seismic monitoring system is through the two steel <br />pipes in a single well, as for the surveyed We1128-21. <br />For a mine zone 400 to 600 feet thick, three combinations of source and receiver sets are <br />recommended: <br />1. In the first set (figure A3), the string of 10 hydrophones should be installed at the <br />bottom of the production pipe*. The sources should be fired in l O locations at 20- <br />ft intervals starting from the bottom of the injection pipe. This configuration <br />should target mainly the inner boundaries of the extraction zone with emphasis on <br />the horizontal extent of structural changes. <br />2. In the second set (figure A4), the location of hydrophones should remain <br />unchanged and 10 sources should be fired in 20-ft intervals over a depth range of <br />180 to 200 feet below the Gas Cap. The depths of the shots should be set so the <br />shots overlapping the hydrophone array be fired half way between the <br />hydrophones. This configuration of sources and receivers should target the upper <br />part of the extraction zone and the vertical features below the line of sources. <br />3. In the third set (figure AS), 10 shots should be fired in 20-ft intervals over a range <br />of 180 feet up starting from 20 ft above the Gas Cap. The hydrophones should be <br />located above the line of shots, with the bottom phone 220 feet above the Gas <br />Cap. This configuration of sources and receivers is intended mainly to target the <br />Gas Cap and the top of the extraction zone. <br />* It maybe beneficial to modify the hydrophone cable so the first five bottom phones are <br />spaced 10 feet apart, with the remaining phones spaced 20 feet apart. This arrangement <br />should increase the number of phones below the Gas Cap and would be useful for <br />reflections inside the system of caverns within the solution mining zone. <br />The presented sequence appears to offer an optimal approach for sufficient <br />characterization ofthe solution caverns developing around a single well. <br />Construction and Handling of the Hydrophone Cable <br />The internal structure and hook-up of individual hydrophones needs to be improved to <br />reduce the possibility of mechanical damage to the seal of the phone installation and <br />subsequent malfunction of the hydrophones. This particularly applies to the parts marked <br />as 13 and 29 in the section view of a hydrophone shown in Appendix B. <br />The bottom eyelet needs to have a strain relief, possibly protected by a stretchable rubber <br />boot to keep the bottom of the cable sealed, even for loads up to 1001b, as the elasticity <br />of the Kevlar core is higher than that of the seismic cable. <br />10 <br />