OrcaFlex examples

Below is a list of links to OrcaFlex example topics. Within each topic are a number of examples which each comprise one or more simulation files, a description pdf file, workspace files and sometimes other supporting files. The files for each example are zipped for easy download. The simulation files can be opened and viewed with the demonstration version of OrcaFlex.

Production risers

A01 Catenary and wave systems

In this example, four types of riser system are shown: a simple catenary, a lazy wave, a steep wave and a pliant wave.

The examples illustrate:

  • Variation of drag coefficient with Reynolds number.
  • Bend stiffener modelling.
  • Modelling of buoyancy modules.
  • Extending the simulation.
  • Modelling tethers and their clamps.

A02 Midwater arch systems

In this set of examples, three types of riser system are shown: a lazy S (both simple and detailed), a steep S and a pliant S. Generally, an S configuration is similar to a catenary but has support provided by an arch structure at a midwater depth.

The examples also show:

  • Modelling of midwater arches.
  • Contact between lines and with shapes, including friction.
  • Modelling bridles and tethers.
  • Using supports to model arch gutters.
  • Setting the model North pointer.

A03 Jumper to high tower

Flexible jumpers connect a spread-moored FPSO to a high riser tower in deep water, i.e. the tower top is close to the surface. The lines descend to the seabed as rigid structures clamped around the tower. An installation of this type can be found in the Girassol field.

The example illustrates:

  • Modelling bellmouths.
  • Multiple wave trains.
  • Modelling a riser tower.
  • Modelling slug flow.
  • Line contact.

A04 Disconnecting turret system

This model represents an FPSO system with a releasable turret. Disconnecting systems are found in regions where typhoons or ice flows are common. It allows the vessel to be removed until conditions improve.

The turret can be lowered from the vessel with winches. However, downtime is expensive, so operators prefer to keep producing until the last moment before disconnecting the turret and departing the field. The turret drops below the severe weather until the FPSO returns to reconnect.

The turret system needs to be designed so there are acceptable responses in all three phases.

  • Connected - the turret is attached to the vessel and moves with it.
  • Disconnecting - the flexibles are disconnected from topside and the turret is released.
  • Disconnected - the turret is settled deeper in the water.

A05 Steel catenary riser systems

This example contains three examples of steel catenary risers (SCRs).

These are:

  • Catenary with spar.
  • Catenary with semisub.
  • Lazy wave with FPSO.

The example also illustrates:

  • User specified units.
  • Homogeneous pipe properties.
  • Adding coatings and linings to lines.
  • Modelling strakes.
  • Modelling tapered stress joints (TSJs).
  • Modelling flex joints.
  • API RP 2RD stress code check.
  • Vessel drawing techniques.

A06 SHEAR7 interface

This example illustrates how to access the OrcaFlex interface to SHEAR7, using the steel catenary riser system considered in the A05 Catenary with spar example.

SHEAR7 is a third-party program, distributed by AMOG, which performs frequency domain VIV analysis. A separate licence is required to run SHEAR7 through the interface. However, the example results can be viewed without a SHEAR7 licence.

The purpose of the example is to demonstrate how to access the interface, what input data are required and how to access the VIV results. The example does not address how to choose appropriate values for the SHEAR7 data inputs, as these relate to SHEAR7 itself, rather than the OrcaFlex interface.