2011-10-13_HYDROLOGY - P2008046 - Laserfiche WebLink

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C` paper 00011980, which is included as Attachment 4. The bond index is determined as follows: Left Track Depth Track Middle Track Right Track Attenuation Log — Attenuation 0% BI = Attenuation 100% — Attenuation 0% Where: Attenuation measured = log reading converted to attenuation Attenuation 0% = .5 dB /ft (free pipe) Attenuation 100% = 10 dB /ft (100% bonded) Amplitudes were converted to attenuations with Schlumberger chart M -1. The result of the bond index calibration is shown in Attachment 5 as a graph of Log Amplitude vs. Bond Index. Based upon published data less than 5 feet of continuous 80% Bond Index (BI) will provide hydraulic isolation for 41/2 inch casing. . Longer intervals of lower BI provide hydraulic isolation. Attachment 6 contains the SPWLA paper discussing Bond Index and the intervals required for isolation. DISCUSSION OF CBL -VDL AND BOND INDEX RESULTS Each CBL -VDL log was run from TD to surface. Transit times were reviewed and are relatively constant over the logs at around 255 µsec, as expected for the 4 1/2 inch casing, fresh water and the 3 ft receiver - transmitter spacing. The transit time readings provide log quality control and confirmation that the software detection gates were properly adjusted and properly operating. Repeat sections were reviewed and found to have consistent measurements between with the main logs. The VDL displays the waveform of the 5 foot receiver transmitter pair. The VDL display agrees with the amplitude measurements showing waveform attenuation in areas of low amplitude. Formation arrivals can be seen in many areas of the log. These formation arrivals indicate cement to formation bonding since a physical connection between the cement sheath and the formation is required to transit the formation reflections. The formation arrivals can be seen on the VDL track about mid way between the first arrival and the right hand side of the track as a variable response, . contrasting with the straight line casing and mud arrivals. Formation arrivals can usually be correlated to open -hole sonic and/or resistivity logs. Attachment 7 shows my Bond Index determination for well TM -2, TM -3, TM -5 and TM -6. Individual log plots for each well are included as Attachments 8 through 11. Also identified on the logs are several of the important formations and hydro - stratigraphic units. The log presentation for each well is: Gamma Ray and Transit Time Red Flag indicating Bond Index above 80% CBL Amplitude Bond Index Shading