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Underground Injection Control Branch Guidance No. 5 <br />.L • <br />wy~ yg://35/htt p://w w w.e pa. gov/reg Soh2o/u i s/r5_O5. h t m <br />The scaling of logs is a matter of importance. Features of significance are emphasized by <br />compressing the depth scale and expanding the temperature scale. A depth scale of one or two inc <br />per 100 feet, and a temperature scale of one inch to two degrees Fahrenheit are appropriate in alrr <br />every case. <br />If multiple logs aze run while shut in, they should be displayed on the same axes (depth scale) for <br />comparison. To avoid confusion, it may be necessary to reduce the temperature scale, but reducin <br />to less than four degrees per inch should be done only when necessary to avoid superimposing <br />logging traces which cannot then be followed. <br />It is very helpful if a gamma ray log is run simultaneously with the temperature log. Collar locato <br />logs are less helpful, but one or the other is necessary for adequate depth control. If a pre-injectio <br />temperature log is available from a well in the area, i[ should also be submitted or referenced if <br />already in possession of the USEPA. <br />D. Procedures for Running the Temperature Log <br />The following steps should be followed for effective temperature logging: <br />1. Shut well in for sufficient time for temperature effects resulting from well constrvction Peal <br />to dissipate. This typically requires at least 36 hours in Region 5. If 36 hours prior to loggir <br />are not available, proof that sufficient time has elapsed can be demonstrated by comparisor <br />with another log of a well at the same site. The second log may have been made previously <br />second log may be made six hours after the first; <br />2. Calibrate the log if at all possible. This can be done by comparing measurements made usil <br />the tool in any two liquids to the known temperatures of those liquids. For instance, both a <br />thermometer and the thermistor to be used for the logging may be used to measure the <br />temperature of water at ambient conditions and a bucket of ice water. Even a single <br />measurement made in a well-mixed bucket of ice water may be very helpful; <br />3. Log the well from the surface downward, lowering the tool at a rate of no more than 30 fee <br />minute. The 30 feet per minute limitation is a practical balance between the tool response t <br />and normal time constraints, slower speeds provide increasing detail. Time coding of the Ic <br />either a tick or gap in the log grid at one minute intervals or a logging-speed trace, should t <br />used [o confirm the tool speed; <br />4. If the well has not been shut in for at least 36 hours before the log is run, comparison with <br />either a second log run six hours before the time the log of record is started or a log from <br />another well at the same site showing no anomalies should be available to demonstrate nor <br />patterns of temperature change. <br />E. Interpretation <br />Confirm the validity of the log at the well site by comparing two logs made at [he same site. Whe <br />lithology and injectate characteristics are similar, then thermal effects along the well bore should <br />be very similar. After the temperature effects caused by casing joints, packers, well diameter, casi <br />string differences, and cement have dissipated, the temperature profiles should be similar, althoul <br />no[ identical. If construction features are evident, a longer shut-in period is probably needed. <br />20 0(34 5/28/99 I :09 PM <br />