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OBJECTIVES <br />The objective of this study and report is to review all the available cementing and cement <br />evaluation information for AMSO's TM -1, TM -2, TM -3, TM -4, TM -5 and TM -6 wells <br />and to opine on the quality of hydraulic isolation. AMSO's "TM" wells are tomography <br />wells used to monitor the advancement of the retort process. <br />ISOLATION REQUIREMENTS AND DEPTHS <br />Attachment 2 is a cross section showing the various formations present from ground <br />level down to the RO zone of the Parachute Creek Member (Green River Formation). In <br />addition, Attachment 7 (cement bond logs and calculated cement bond index for wells <br />TM -2, TM -3, TM -5 and TM -6) shows key hydrostratigraphic zones. The depths <br />referenced on the cross section are measured from ground surface. I have added 4 feet to <br />these depths in order to equate them to the various cement evaluation logs which were <br />depth referenced to the drilling rig's kelly bushing at 4 feet above ground level. The <br />most critical areas in which isolation must be achieved are: <br />1. Between the R1 zone and the Dissolution Surface <br />2. Between the L3 hydrostratigraphic unit (HU) and the `B" Groove L6 <br />3. Between the "A" Groove L7 and the Uinta HU <br />4. Above the Uinta HU. <br />Additional isolation can be demonstrated by adequate cement placement and bond in the <br />"R" zones. "R" zones are typically of relatively high kerogen content and exhibit low <br />permeability and are therefore excellent confining intervals. <br />Hydraulic isolation of zones within a wellbore does not require the entire well annulus to <br />be perfectly cemented. While this is a desirable condition, perfect cement jobs are rare. <br />Adequate hydraulic isolation can be achieved with cemented intervals of sufficient length <br />above and below a given zone that prevent fluid movement along the wellbore. <br />AVAILABLE LOGS FOR REVIEW <br />Numerous cement evaluation logs have been run on the tomography wells. Attachment <br />3 summarizes the logs that have been run. Note: additional logs were not possible on the <br />TM -1 and TM-4 due to permanently installed tubing and instrumentation. <br />BACKGROUND INFORMATION ON CEMENT EVALUATION LOGS <br />Halliburton CAST (Circumferential Acoustic Scanning Tool) Log <br />2 <br />