DeepSea EXPRES Subsea Cementing Head

System for Launching Plugs with Subsea Wellheads

The DeepSea EXPRES subsea cementing head comprises the Surface Dart Launcher (SDL) and Subsea Tool (SST).

The SDL contains identical darts launched during cementing. The darts release casing wiper plugs when they reach the SST. Since the SDL is modular, adding segments is easy. This increases the number of darts that can be launched.

Using darts instead of a "free fall" ball helps prevent contamination, provide positive fluid displacement, and save time.

High pumping rates improve and facilitate mud removal

After dart launch, mud flows down the drillpipe, through the sliding sleeve of the SST, and out of the orifices. The dart lands on a rod and continued pumping forces the dart and rod down, pushing the plug out of a basket. A spring retracts the sliding sleeve, allowing complete, unobstructed flow through orifices.

A pressure differential resists rapid rod motion and stops rod movement after plug release. Combined with plug friction, this causes increased pumping pressure and provides indication of plug launch. Spacers prevent plugs from sticking and are retrieved with the tool.

The downhole SST encases plugs inside a basket, eliminating difficulties associated with pumping fluids through the inside of plugs. Simplified plug design allows use of high-performance, easily drillable plugs.

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