Zenriser

Application

Oil and Gas industry operators; Offshore engineering contractors; Riser, pipeline, flowline, cable and hose manufacturers and installation contractors.

Introduction

Zenriser simulates the dynamic behaviour of single or multiple offshore flexible or rigid riser or pipe systems subject to hydrodynamic loading and vessel motion.

It performs 3D static or dynamic analyses of any pipe system and supports many options and features which make the program both powerful and user-friendly.

Zenriser can assist at any stage in the development of a riser or pipe system from a feasibility study through conceptual and detailed design to installation and operation. It can be used for preliminary static analysis to determine a system layout, for global dynamic response analysis to assess overall system response and for detailed dynamic response analysis to design particular components. It can also be used to determine clearances between flexible risers, mooring lines and pipelines.

As well as being able to study conventional single or multiple flexible riser systems (steep-S, lazy-S, steep wave, lazy wave, free hanging), Zenriser can be used to analyse a generalised multiple pipe situation composed of a series of pipes with any change in weight, stiffness or hydrodynamic properties along their lengths and clamped (tie-in) boundary conditions / bend stiffeners or flexjoints / taper joints.

Any tethered or untethered subsurface body (buoy or weight) and any distributed buoyancy tanks, collars or clump weights may also be attached to the riser system. The motions of up to 2 vessels may be defined (vessel response, time history, etc.) and applied at any end of any pipe as a boundary condition.

In addition, any external environmental loading may be applied to the system from any direction (single wave, irregular seastate, multi-directional current profile). Contact between the pipe and an irregularly shaped surface may also be analysed and both axial and lateral friction are modelled.

Zenriser consists of a static module - for fast determination of system layout, and a dynamic module - for advanced static analysis, global dynamic or detailed dynamic response analysis. The static mode is based on a fast solution scheme and allows efficient determination of system geometry via parametric studies.

Technical capabilities

• Analysis types
  • fast 3D static analysis with optional current loading, vessel offset and axial / lateral seabed friction
  • 3D dynamic response analysis.
• Structural details
  • any number of riser lengths connected between 1 or 2 vessels, fixed points in space or to a common subsurface buoy / weight
  • any riser properties along length (cross-sectional dimensions, bending, axial and torsional stiffness, mass, hydrodynamic properties)
  • any node numbering system for any riser length
  • change in element length along risers
  • content density input separately for each riser length
  • linear change in either bending stiffness or thickness between any 2 nodes on a riser length
  • any number and length of distributed buoyancy tanks or clump weights
  • cable attachments along riser lengths
  • a single subsurface buoy connected at the end of any riser length.
• Boundary conditions
  • analysis started from a static solution or from a configuration that has been saved from a previous analysis
  • pinned, rotational stiffness or clamped end boundary conditions at any end of a riser length
  • specification of each vessel centre of motion allowing easy input of motion phase angles
  • any movement of either or both ends (linear translation, time history)
  • excitation of either or both ends about centre of motion (single wave response, transfer functions of motion, non wave-related cyclic motion)
  • flat seabed with seabed reaction and static and dynamic axial and lateral friction models
  • contact between riser and user-defined irregular surface with surface reaction force and friction models.
• Environmental conditions
  • waves and current applied in any direction
  • single wave (regular Airy, Stoke's 2nd order, Stoke's 5th order wave theories)
  • irregular seastate (Pierson-Moskowitz, JONSWAP, user-defined wave spectra)
  • any multi-directional current profile.

User friendliness

• Analysis execution
  • interactive simulation
  • batch submission of up to 24 jobs.
• Full screen menu-driven interactive input
  • multi-structured menu system
  • full description prompts & input fields
  • help function available for each screen.
• Control of data input, analysis and output
  • all input data entered and modified through the menus and screens (no special text editors required)
  • full automatic error checking at input level with informative error messages
  • input in Metric or Imperial units, with analysis review in either unit system
  • processing and reporting under menu control.

Result output and presentation

• simulation input data reports
• full user selection of contents and range of results
• all results available on screen, file or hard copy (graphically and as tables)
• standard tables and colour coded plots of envelopes (minimum and maximum values), time histories and configuration
• inclusion of wave surface and seabed on relevant plots
• colour coded animated display of riser motion and wave surface with interactive view rotation
• highlighted display of riser sections where results exceed a user-specified limit.

Availability

• Zenriser runs under Windows 98, NT, 2000, XP and requires a USB port
• the program is supplied with a comprehensive User Manual, set of examples and USB hardware lock.

Support service

• software updates
• documentation updates
• telephone, e-mail and web support.

Consultancy

Zentech International Ltd. offers a comprehensive offshore analysis service. Zenriser is one of several products used to meet the demands of the industry. We are always pleased to discuss the addition of new features to meet the particular requirements of a client.

Name change

The Zenriser program was previously known by the name FLEXRISER.