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5 PART ZV - CDNCLUSI027S - REMINDERS Different pipe weights and cement types will affect the log readings, so be mindful of these factors in wells with varying pipe weights and staged cement or squeeze jobs. Collars generally do not show up on the VDL track in well- bonded sections of casing. Langer (slower) travel time due to cycle skipping or cycle stretch usually suggests good bonding. Shorter (Easter) travel times indicate a de-centered tool ar a fast formation and •.rill provide erroneous amplitude readings that make evaluation impossible through that section of the log. Fast formations do not assure that the cement contacts the forr.:ation all around the borehole. Although the bona :rdex _~ important, you should not base your assessment cf the ~_ement quality on that one factor alone. You should use she vDL to support any indication o! bonding. Also, you must know how each portion of the C8L (VDL, travel time, amplitude, etc.) influences another. Most ]'-5' C8L's cannot id=ntify a 1/2" channel in cement. Therefore, you also need to .:onsider the thickness of a cemented section needed to provide zone isolation. For adequate isolation in injection wells, the log should indicate a continuous eoi or greater bond through the following intervals as seen in TABLE 1, below: TABLE I - IT!'I'ERVALS FOR ADEQUATE BOND PIPE DIAMETER ( in) I COl7TI:IUUUS I27TERVAI, KITH BOND ? 80t (ft~ 4-1/2 I LS 5 15 5-1/2 I 18 ~ ]] 7-5/8 ]6 9-5/8 45 10-3/4 I 54 Adequately bonded cement by itaelt will not prevent fluid movement_ I! the bond log shots adequate bond through as interval there the geology allore fluid to move (permeable and/or fractured zoaee), fluids may move around perfectly bonded tomcat by travelling through the formation. A a s crow-chart your bond log rith open hole loq~ to sus that you have adagnate bonding th=ough the proper iaterval(a!.