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clock Created with Sketch. 24/06/14
17:59
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Originally posted by spawk
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I don't believe the hydrates explanation can be relevant here simply because the 10 June ann stated that the 13 3/8ths csg had been set prior to the rig undergoing unscheduled maint. When casing is set it is cemented to the surrounding formations and an integrity test run to check that the cementing job has no discernable flaws. As part of this process a cement floor is placed in the well (casing shoe). This means the well had been totally isolated from the surrounding formations and not subject to inflow of any combination of methane, water, or any other fluids. Any comment about hydrates could still be relevant but they would relate to sea floor conditions imo. Occasionally, rig anchors or placement of the surface conductor can disturb the sea floor in such a way that methane hydrates can spontaneously dissociate and methane bubbles to the surface. This is of course a major safety hazard for the rig.
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Just to add: this is a new generation semi-sub rig and I don't know if they use anchors or dynamic thrusters to maintain position over the well bore. Depth at 1427m subsea with brand new rig suggest they might be using thrusters (normally built into the rigs 'legs').
(20min delay)