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Underground Injection Control Branch Guidance No. 5 • wy~i wyg://35/h «p://ww w.epa. gov/reg5oh2o/u i c/r5 _O5. h tm curves, and CBLs should include an acoustic variable density log (VDL). The left hand track shoe contain the gamma ray and casing collar log. The right hand tracks should contain the acoustic amplitude and travel-time curves in track 2 and the acoustic VDL in track 3. CETs include a graphical depiction of the cemented area of the well bore in track 3. If available, a shop calibratio record should be attached. The surface pressure under which the log was run should be noted on t log form. In new wells, the cement should be allowed to set for at least 72 hours before logging. D. Procedures for Recording the Cement Bond Log (CBL) or Logs made Using Cement Evaluation Tool (CET) 1. Centralize the tool. Be sure [hat the part of the hole to be logged is liquid filled. Calibrate tl tool; 2. Record the amplitude and travel time measured by the short-spaced receiver in the fixed ga mode; Run the CBL over the entire cemented length of the casing and through at least two joints t the uncemented portion, if any; 4. Check the travel time. If intervals are found having four microseconds less than travel time free pipe, check the tool centralization and relog the well if necessary; If the log indicates poor bond, the log can be run under pressure to eliminate any micro-annulus effect. The pressure used should be minimal to prevent enlargement of the micro-annulus. Often reproduction of the pressure used during cement setting is sufficient. Class I wells (although cement logs are occasionally required at Class I sites, they are not a demonstration of part 2 of MI) pressurizing to the normal annulus pressure may be sufficie eliminate the micro-annulus; and 6. Check the tool calibration. If significant tool drift has occurred, relog the well with the bacl tool. E. Interpretation Interpretation of records Most cement records document the volume of cement emplaced between the casing and the well bore. For demonstrations of MI for Class [[ wells, [he records must indicate [hat cement was emplaced at locations which will prevent upward movement from the injection zone. For demonstrations of MI for Class III wells, the records must indicate that cement was emplaced at locations which will prevent upward movement from [he injection zone and into or between USL Interpretation of CBLs The log is examined to identify the location of cement along [he casing. Only a few feet of sound cement are required to prevent flow along the well bore, but in most cases making judgements ab the adequacy of a few feet of cement will not be required because [here will be more than 10 feet cement indicated to be sound, or there will be no indications of sound cement in critical areas. If ; initial cement bond log does not indicate the presence of cement, often a second log will be run N pressure on the casing. This may show cement while [he earlier log does not. In this case, a ? 1 or?4 5/28/99 I :09 PM