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Memo to Greg Vaughn -2- 27 February 1990 <br /> Kearney OF <br /> casing, it would not be possible to run bond or variable density logs to evaluate <br /> the adequacy of the squeeze job. I have other comments and concerns which are <br /> listed below and must be considered prior to performing the well abandonments. <br /> 1. Cement volumes were not specified. Because there will be limited control <br /> on the placement of cement in the annulus and because of the permeable <br /> conditions of the gravel pack and the intermediate and lower coarse-grained <br /> zones, there should be an extra supply of cement. A rule-of-thumb for <br /> cement use in a squeeze job is two sacks of cement per foot of perforated <br /> interval . However, because of the low pressure and permeable conditions, <br /> even more cement may be necessary. <br /> 2. A slurry of neat cement is inappropriate for the conditions. Accelerators <br /> will probably not be necessary because the heat generated from the firing <br /> of the explosive charges may accelerate the hydration of the cement. <br /> However, because of the low pressure and high permeability conditions, <br /> fluid-loss control of the slurry is crucial . The use of fluid-loss <br /> additives is strongly recommended. Fluid-loss will also be exacerbated <br /> with high water-to-cement ratios. <br /> 3. Pressures were not discussed. Because the plan appears to be a low- <br /> pressure squeeze, the bottom hole treating pressure will be less than the <br /> fracture pressure of the formation and a pressure build-up may not occur <br /> until late in the squeeze job. Final safe squeeze and maximum allowable <br /> surface pressures should be calculated prior to performing the squeeze. <br /> In addition, an injection test using uncontaminated water, can give the <br /> approximate injection rates to be expected at the low pressures. <br /> 4. A report of the well abandonment (or well destruction) must be filed with <br /> the Department of Water Resources. <br /> The 29 January 1990 letter did not contain any plans for the Phase II monitoring <br /> wells to be installed in the shallow water-bearing zone. In our letter of 8 <br /> November 1989, we required that the designs for these shallow monitoring wells <br /> and the well abandonment plans be submitted. The well designs have been <br /> discussed with Hargis since that time. In a meeting with the DHS and Hargis on <br /> 6 December 1989 and in a telephone conversation with Peter Quinlan on 9 February <br /> 1990, it was agreed that the Phase II shallow monitoring wells will be installed <br /> with screen lengths greater than ten feet. In that meeting, I concurred with <br /> Hargis that it would be acceptable to screen the remaining portion of the shallow <br /> water-bearing zone, which could be up to 30 feet in length. However, the shallow <br /> monitoring wells are not to penetrate the intermediate sand. The longer screen <br /> lengths are necessary so that the monitoring wells will be functional in <br /> conditions where there has been a historical regional dewatering of the aquifer. <br /> If the drought continues into 1990, it would cause the ground water levels to <br /> to decline even further. <br /> CKW:jj <br />