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not be obtained at this pumping elevation. It is recommended that the pump <br />be reset at a lower elevation and a second pump test be conducted. It is <br />impossible to estimate o-ihat elevation will be reouired, however, fron exper- <br />- fence, it is believed that a pump depth of 500 feet or more may be <br />needed. <br />NNG-21 <br />Test well NNG-21 is located near the east-west axis of the synclinal <br />basin mentioned above. This hole was drilled for exploration purposes to <br />a depth of 1600 feet. In addition, NNG-2]C, a core hole, was drilled 20.95 <br />feet south of NNG-21. NNG-21C is cased and cemented to a depth of 2790 feet. <br />The casing in NNG-21C was perforated in fourteen sand zones at two shots per <br />foot. The zones of perforation are as follows: <br />262-293 feet 1125-1135 feet <br />320-385 1140-1148 <br />420-435 1224-1289 <br />530-542 1340-1355 <br />617-628 1366-1385 <br />690-700 1430-1445 <br />838-850 1475-1525 <br />The sand zone at depth 320 to 385 feet was selected to be perforated <br />' prior to perforation of all zones. Pressure data was collected by 11r. D. <br />R. Dudrey of Northern Natural Gas Company for approximately 1.5 hours, and <br />is included in Table 2. Data was also collected after all the zones had <br />been perforated, and is included in Table 3. Review of the data indicates <br />that approximately 26 percent of the total aquifer head is provided by the <br />• sand zone between depths 320 and 385 feet. It was noted by Mr. Dudrey, that <br />a temporary pressure drop appeared when the sand zone between depths 530 and <br />-2- <br />