As well as Ultimate Cement Placement, many users have recognised multiple other inherent benefits of this technology, but the one which will be explored in this discussion is the capability to remove the requirement for overside work within the moonpool when running a casing string.
Fast response cover
If an operator wishes to circulate through their casing in the open hole with the traditional poor-boy inner string set-up, whereby open-ended pipe is run beneath the wellhead running tool, it is required for the ball/snorkel valve through the running tool to be closed and sealed.
Traditionally, it is done by running the wellhead as close to the sea level as practical within the moonpool, whilst establishing circulation through the top drive system (TDS), after having connected to the first stand of landing string. The circulation through the float shoe lifts the seawater level within the casing to the wellhead running tool ball valve, flushing the air within the casing and allowing the engineer to close the ball valve in preparation for running in the hole, with the capability to circulate down.
Having an engineer in position to go and close the ball valve is not as straight forward as it may sound, as more often than not this process requires over-side cover in order to ensure the safety of the engineer working over the open water.
If the sea-state is in excess of the safe limits for a fast response craft to provide the necessary over-side cover, the operations may be impacted, with the operators potentially forced to wait on weather until suitably favourable conditions exist. Alternatively, a subsea system, such as a Remotely Operated Vehicle (ROV), might be utilised to close the ball valve after the air has flooded, which introduces risk of not being able to circulate in the open hole until that operation has been complete.
When utilising SeaCure®, the casing string is sealed by the inner string once the SeaCure Bottom Hole Assembly (BHA) is engaged into the float shoe, enabling for top filling of the air gap at the rotary table.
The flushing of the air gap at the rotary table and subsequent non-reliance of closing the ball valve can mitigate the requirement to obtain over-side cover when running certain casing strings, eliminating risk, saving time as well as cost, and ultimately delivering more efficient operations.