Table T4. Quality control characteristics and sonic log data, Hole C0001D. (See table notes.)
| Depth interval (m LSF) |
Zone | Quality | Comments | |
|---|---|---|---|---|
| Top | Bottom | |||
| –12 | 0 | 1 | 0 | Strong arrivals at ~203 µs/ft. No apparent change in the arrivals as the tool crosses the seafloor. |
| 0 | 31 | 1 | 0 | Strong arrivals at ~203 µs/ft. No apparent coherence at slowness less than mud velocity (Fig. F7). |
| 31 | 84 | 1 | 0 | Strong arrivals at ~200 µs/ft. Not clear if this is due to change in mud velocity. Occasional short (~1 m) increases in slowness of the mud arrival. |
| 84 | 175 | 1 | 0 | Strong arrivals at ~195 µs/ft. Not clear if this is mud velocity or the emergence of formation velocity. |
| 175 | 192 | 1 | 1 | Distinct formation and mud arrivals. Formation arrival variable around 180 µs/ft (Fig. F8). |
| 192 | 202 | 1 | 0 | No distinct separation between formation and mud arrival. Slowness varies around 195 µs/ft. |
| 202 | 325 | 1 | 1 | Distinct formation and mud arrivals. Formation slowness variable around 180 µs/ft and dropping gradually with depth (Fig. F9). |
| 325 | 476 | 1 | 2 | Distinct formation and mud arrivals. Coherence decreases, with occasional gaps several meters thick, in which picks are not clear. Formation slowness more variable with depth (Fig. F10). |
| 476 | 524 | 1 | 2 | Arrivals are more broken up in depth. The picks seem to be skipping between distinct arrivals creating noisy data with large slowness swings on a scale of 1–5 m. |
| 524 | 589 | 2 | 2 | Arrivals are broken up in depth. The picks seem to be skipping between distinct arrivals creating noisy data with large slowness swings on a scale of 1–5 m. |
| 589 | 822 | 2 | 2 | Arrivals are broken up in depth. The picks seem to be skipping between distinct arrivals creating noisy data with large slowness swings on a scale of 1–5 m. However, there seem to be longer sections 5–15 m that show continuous coherency and perhaps represent real slowness variability. |
| 822 | 874 | 2 | 2 | Large (10–20 m) gaps in coherent arrivals. Picks in this range are only sporadically reliable (Fig. F11). |
| 874 | 964 | 1 | 2 | Return to reasonable signal strength and coherence. There are still intervals with data gaps, but 10–20 m sections have continuous reliable data (Fig. F12). |
Notes: LSF = LWD depth below seafloor. See “Data and log quality.”
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