Drill-in Wellhead System

Overview

Geoprober has worked closely with Statoil to design a new slim-hole exploration wellhead system that enhances offshore top-hole casing drilling from a semi-submersible vessel. Traditionally, casing drilling has had very little uptake for offshore drilling due to the risk of not being able to land out the casing hanger in the wellhead. Geoprober has eliminated this risk through its breakthrough drill-in wellhead system.

Benefits

By eliminating trips through the water column and reducing the diameter of the exploration well, a dramatic cost saving can be achieved for operators. While part of this cost saving is realised through time savings, a further significant saving comes from reduced well materials and associated logistics.

Our Solution

Geoprober’s solution is a wellhead system that allows the surface casing driller to hang off, seal and cut the casing within the wellhead. The exploration wellhead is run on the surface casing with the bottom hole assembly (BHA) attached and then locked into a pre-installed foundation. The casing is released by the internal grippers and the casing drilling can commence. The cuttings returns are directed to the sea floor through vents in the pre-installed foundation with a low pressure seal preventing cuttings from entering into the wellhead (the cuttings can be recovered to surface if required). Once the target depth is reached, the casing is spaced out and the grippers are activated to hang off the casing.

The BHA is then retrieved on wireline (or drillpipe if desired) before the high pressure seals are activated and tested to ensure well integrity. The surface casing is cemented in and the casing is then cut within the wellhead with excess casing retrieved back to the vessel. The surface casing is now established with the BOP and riser then deployed allowing the first intermediate hole section to be drilled conventionally.