Bentonite gel mud was used exclusively during the leg. The immediate concern was to use up the 10 MT of excess bentonite stored in P-Tank #7 that was delivered to our embarkation port call in Cape Town I . Since P-tank #7 is normally a sepiolite tank, we needed to empty it prior to arrival back in Cape Town so the additional 27 MT of stored sepiolite could be loaded aboard. Once the tank was emptied, we continued using the gel mud from P-tank #1 for the following reasons: this was a less expensive sweep mud, we were drilling in a hard-rock (basement) hole without expanding clay concerns, and the Bentonite gel appeared to be effective because we were not seeing fill on connections or between bit trips.

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