its on team, page-41

So it sounds like the kick could have been for one of two reasons.

1. They used an inappropriately light mud for the known conditions (ie data from other nearby wells, if shared by drillers or logged with national authorities), or expected conditions.

2. The mud weight was appropriate for what could have been expected, but the pressure down hole caught them by surprise!

Maybe Ya or someone else with some technical expertise could either confirm this theisis, or set this armchair expert right.

Opinions appreciated.