OrcaFlex Examples - B Drilling Risers

B01 Drilling Riser.zip (2.0 MB) – Description PDF (304 KB)

A tensioned drilling riser descends from a semi-submersible drilling vessel to a BOP on the seabed. The semi-sub has been offset 30m from the BOP.

B02 Workover Riser.zip (27.6 MB) – Description PDF (308 KB)

A workover riser is deployed from a semi-submersible drilling vessel. The lubricator assembly is suspended in the drilling derrick and the riser hangs below it, with much of its weight supported by a pair of tensioners hung off the drill floor. Clearance is tight where the riser passes through the drill floor, and this area is an important point of interest in the analysis.

B03 SPAR.zip (2.6 MB) – Description PDF (364 KB)

A riser descends from a Spar to the seabed via a guide down a central moonpool. A constant tension device supports the top of the riser.

B04 Clashing Risers.zip (16.7 MB) – Description PDF (347 KB)

Two drill strings are hung from a MODU. Pairs of strings are used if one string has to be disconnected and drilling is required to continue. In this model one string is connected to the wellhead while the other has been released and is being raised to the drilling vessel.

This simulation looks at a snap-shot of the raising operation, assuming that the total free riser length remains constant, and applies a regular design wave. The risers are close enough together that hydrodynamic effects due to the wake shed by the free riser lead to clashing between the two drill strings. The clashing is analysed, and the effect of the wake behind the free riser is included in the model.

B06 Running BOP.zip (21.5 MB) – Description PDF (310 KB)

A blow out preventer (BOP) stack is lowered to the seabed for connection to the wellhead. Guide wires are used to restrain the BOP while it is lowered.