Operating Envelope
The typical operating envelope is illustrated below. This will be extended with the commercial introduction of the first expandible and then mono-bore wells. In shallower waters the casing for more than one well can be carried on the vessell The surface casing ( 7-5/8" ) is set as deep as possible. This is to maximise the operating envelope which is limited by the ability of the surface formations to support the pressure of mud circulation to the surafce.
Kick tolerance modelling carried out by Argonauta Drilling Services shows the well control operating envelope for the system.
The example id for a well depth of 17,000ft (5,180m) a water dpth of 8,000ft (2,438) and an initial mud weight of 9.5ppg (1.14 sg).
The fracture gradient used is typical for deepwater. The 7-5/8" surface casing is set at 3,000ft (914m) BML, the 5-1/2" liner set at 6,000ft (1,828m) bml and the well drilling at 9,000ft (2,743m BML) |
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