Mamoun Naciri

SBM Offshore · Engineering - Hydrodynamics

Mooring Integrity Management (MIM) is a key operational aspect for FPSO operators, mooring system designers and Recognized Classification Societies (RCS). MIM programs should include the capability to detect a mooring line failure. When direct or indirect measurement of line tension is available continuously and reliably over time, this requirement...

For decades now, wave basin model tests have been the cornerstone of the verification of new concept global performance. Model tests are also the preferred approach to shed light on complex hydrodynamics phenomena that cannot be correctly handled by the conventional seakeeping engineer’s toolbox. Two decades ago, model tests were performed on a see...

Mooring Integrity Management (MIM) is a key operational aspect for FPSO operators, mooring system designers and Recognized Classification Societies (RCS). MIM programs should include the capability to detect a mooring line failure. When direct or indirect measurement of line tension is available continuously and reliably over time, this requirement...

For decades now, wave basin model tests have been the cornerstone of the verification of new concept global performance. Model tests are also the preferred approach to shed light on complex hydrodynamics phenomena that cannot be correctly handled by the conventional seakeeping engineer’s toolbox. Two decades ago, model tests were performed on a see...

Mooring failures have been a recurring issue in the offshore industry, and failures continue to occur across the offshore Floating Production System (FPS) fleet. Many of these recurring failures appear to be from similar degradation mechanisms as past events. To better understand these trends and learn from these events, DeepStar® Project 20401 - D...

The Turret Mooring System (TMS) for the Shell Prelude FLNG (Floating Liquefied Natural Gas) facility consists of a Top Mounted Internal Turret (TMIT) integrated at the bow of the FLNG hull. Permanently connected to the seabed through a dedicated mooring system, this Turret allows the FLNG facility to passively weathervane in response to prevailing...

The design of mooring systems in West of Africa is often dominated by squall events. These are episodes of rapidly increasing wind speeds accompanied with sudden and significant wind direction changes. The response of weathervaning systems (offloading tankers moored to an export system or turret moored FPSO’s) to such transient and violent environm...

The Skarv field, located 210 km offshore Norway, has been developed by BP using a turret moored FPSO, with first oil production achieved in December 2012. This paper presents the station keeping philosophy adopted for the FPSO, and gives an overview of the turret system design, and the challenges involved. In addition, based on four years of offsho...

The prediction of ship motions in extreme seastates is very complex as it involves strong nonlinearities. It deals with high motions of the ship and implies strong mooring system loads. These seastates are usually modeled in tank tests but an alternative in the near future could be CFD computations. In this article, all required steps to setup and...

The prediction of ship motions in extreme seastates is very complex as it involves strong nonlinearities. It deals with high motions of the ship and implies strong mooring system loads. These seastates are usually modeled in tank tests but an alternative in the near future could be CFD computations. In this article, all required steps to setup and...

Owing to friction in the weathervaning system and in the swivel stack of a turret-moored FPSO, the turret can be locked to the FPSO in day-to-day environments meaning that no relative yaw motions occur in such conditions. When the FPSO yaws sufficiently, the mooring yaw restoring moment builds up to a point where the friction torque is overcome fre...

The maximum displacement of turret moored floating production and storage units (FPSO, FLNG) has been steadily increasing over the past decades and is likely to increase even further in the future. Furthermore, some of these turret moored units are designed to keep position in even the harshest of environments (e.g. 10,000-year storms) and very dee...

Development of Turret Mooring Systems (TMS) for harsh environment and large number of risers has led to a drastic increase of the size of the chaintable and consequently of the turret cylinder diameter. Furthermore, harsh environments usually require relatively deep drafts. As a consequence, the volume of entrapped water in large turrets increases...

The reported presence of one third of remaining fossil reserves in the Arctic has sparked a lot of interest from energy companies. This has raised the necessity of developing specific engineering tools to design safely and accurately arctic-compliant offshore structures. The mooring system design of a turret-moored vessel in ice-infested waters is...

A new method of direction-wise interpolation is proposed. Its merits are first presented by considering the interpolation of 1st order motion Response Amplitude Operators (RAOs) and 3D (ω1 , ω2 , θ) wave drift load Quadratic Transfer Functions (QTFs). In a recent publication (see Ref. [1]), the importance of wave spreading on the spectral density o...

Model tests are widely thought as a reliable means of obtaining answers to questions beyond the realm of state-of-the art simulation tools. The author’s experience, no doubt shared with others, has been that whilst providing many answers model tests sometimes raise new questions and unveil phenomena not anticipated at the start. Sometimes these phe...

BP intends to develop the Skarv Field located about 210 km West of Sandnessjøen offshore Norway using a turret moored new-build FPSO. The field is in approximately 375meters of water depth located in the Haltenbanken area of the Norwegian Sea. The Skarv FPSO is provided with a heading control system as the turret, being positioned at 1/3 of ship le...

The need for LNG export and import terminals is anticipated to grow as natural gas progressively accounts for a larger fraction of worldwide consumed energy. These terminals are preferably located nearshore i.e. in relatively shallow water. Design of floating structures is most of the time performed assuming long-crested waves. In shallow water, di...

Recent discoveries in the deep waters of the Santos Basin Offshore Brazil are paving the way for field developments based on spread or turret moored FPSO’s. For decades, model testing of moored floating structures has been a corner stone during project execution. There were mainly two reasons 1) to obtain design loads to feed into the structural de...

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1992. Includes bibliographical references.

The HAWAI (sHAllow WAter Initiative) JIP was launched in 2005. The objective was to improve the reliability of Offshore (LNG) Terminals by combining the expertise of offshore hydrodynamics and coastal engineering to better address key issues regarding motion and mooring prediction methods in shallow water. One of the key issues identified was the d...

The prediction of slow drift motions for the design of a mooring system is usually made using the Newman approximation [1], based on the assumption of a very low resonance frequency of the system and small contribution of the second order wave fields. This hypothesis is commonly satisfied for most parts of the mooring systems in deep water. However...

MURPHY Sabah Oil Co. Ltd. has developed the Kikeh Field located offshore Malaysia in the South China Sea in a water depth of 1325m. This field development is based on a Floating Production Storage and Offloading unit (FPSO) and a Spar Dry Tree Unit (DTU). Fluids are transported in fluid transfer lines (FTL) using SBM’s newly developed and patented...

Extensive model tests of a soft moored LNG carrier in shallow water have been performed in 2004. The focus of this test campaign was on the hydrodynamics of non wall-sided, low drag vessels and the characterization of the model basin performance. The motivations behind this test campaign have been discussed in ref [1] and [2]. Numerical calculation...

This paper describes work done within the EU FP5 Project EXPRO-CFD to develop a system to couple commercial CFD software to existing hydromechanics tools to allow prediction of the response of floating structures in waves and currents, including viscous effects. Its focus is the use of this system to improve the prediction of CALM buoy response in...

The Soft Yoke Mooring and Offloading system (SYMO® ) has been developed in SBM to allow the tandem mooring of an LNG carrier to the stern of an LNG FPSO or a Floating, Storage & Regasification Unit in harsh environments. The SYMO® system consists of two mooring legs supported by a crane. A yoke structure is suspended at the bottom of the two moorin...

fax 01-972-952-9435. Abstract With the LN G market booming, the need for a reliable and safe means of transferring LNG from a producing floating facility to an LNG carrier and from this carrier to a near-shore terminal is becoming acute. In this context, the SYMO ® (Soft Yoke Mooring and Offloading) system has been developed and recently tested in...

With the LNG market booming, the need for a reliable and safe means of transferring LNG from a producing floating facility to an LNG carrier and from this carrier to a near-shore terminal is becoming acute. In this context, the SYMO® (Soft Yoke Mooring and Offloading) system has been developed and recently tested in MARIN's offshore basin. Importan...

With the LNG market booming, the need for reliable and safe means of transferring LNG from a producing, floating facility to an LNG carrier and from this carrier to a near-shore terminal is becoming acute. The Soft Yoke Mooring and Offloading (SYMO© ) system has recently been model tested in MARIN’s offshore basin. Results of these tests are presen...

The ever-rising need for energy and environmental issues have propelled LNG as one of the most promising source of clean energy for the near future. LNG differs greatly from oil when it comes to loading and offloading in at least two respects. Firstly, owing to its temperature at atmospheric pressure (−162°C), Liquefied Natural Gas does not lend it...

Today hard riser, dry tree systems not carried on a bottom founded structure are supported by either a TLP or Spar. Both of these systems directly or indirectly use buoyancy to achieve the riser tensioning. The use of buoyancy requires that the relative motions of the buoyancy and the risers be kept small. The TLP does this by tendon restraining th...

Since the pioneering work of Huse (1986, 'Influence of Mooring Line Damping Upon Rig Motions,' Proc., 18th OTC Conference), it is well known that mooring lines may account for a large fraction of the overall damping present in a moored floating structure. This paper is concerned with the mooring line damping induced by the low-frequency, quasi-stat...

Today hard riser, dry tree systems not carried on a bottom founded structure are supported by either a TLP or Spar. Both of these systems directly or indirectly use buoyancy to achieve the riser tensioning. The use of buoyancy requires that the relative motions of the buoyancy and the risers be kept small. The TLP does this by tendon restraining th...

This paper reviews several approaches to wave drift damping experienced by floating bodies. A heuristic approach first introduced by Aranha giving the wave drift damping tensor for the surge and sway modes of motion in finite depth is used. Results for the surge wave drift damping are compared with experimental results from model tests. These tests...

We study the effects of a long wave of finite amplitude on a short wave propagating in a different direction. To facilitate analytical treatment, the long wave is modelled by Gerstner's exact solution, and Lagrangian coordinates are used. Focus is first on the moderately long-scale modulation within a duration comparable to the period of the long w...

The propagation of plane sound waves, generated from an underwater line source, and strongly scattered by surface waves directly above the source, is examined. The depth of water is shallow enough so that only one guided mode of sound is present. It is shown that, except in the immediate vicinity of the source, outgoing radiated waves are scattered...

The evolution of short gravity waves on long gravity waves on the surface of deep water is studied. Both wave trains are assumed to be irrotational, mild in slope, and slowly modulated in space and time, but their scales are so different that the short wavelength is very much less than the long-wave amplitude. Here, it is shown that the use of Lagr...

To facilitate the theoretical prediction of the evolution of a short gravity wave on a long wave of finite amplitude, we consider a model where the long wave is represented by Gerstner's exact but rotational solution in Lagrangian coordinates. Analytical formulae for the modulation of an infinitesimal irrotational short wave are shown to be qualita...

Part 1: Bragg scattering of sound from a line source by surface waves. The strong scattering of plane sound waves from a line source in a waveguide is analysed for a hard bottom and a soft undulatory surface representing one or two uniform surface waves. In the presence of one surface wave, sound is radiated and scattered in the same two directions...

We present a theory of Bragg scattering of sound by surface gravity waves which are nearly periodic with a slowly varying envelope. Through several examples we illustrate how the resonant scattering of sound from a CW source in shallow water can reveal the characteristics of weak surface waves. Only plane sound waves of a guided mode are studied in...

Recent field experiments have shown that inside the Kelvin wake of a moving ship there can be two soliton-like envelopes, which extend to a long distance behind the ship. The source mechanism of these solitons has so far been attributed to the steady advance of a ship. In this note we suggest that ship oscillations, induced by ambient sea waves, pr...

We extend the recent work on Bragg scattering of water waves by one-dimensional parallel bars of sinusoidal profile to two-dimensional, doubly sinusoidal bed waves. The resonance condition governing the phase matching between the incident, scattered and bed waves is now more complicated and a much richer variety of resonant reflection can occur. In...

A recent theory of Bragg scattering of surface waves by sinusoidal sandbars on a sea bed was applied to three cases: oblique incidence on a strip of infinitely long bars; oblique incidence on the corner of a bar field and sea bed with a mean slope. The Bragg mechanism can be a basis for breakwaters where the soil is not strong enough to support a s...

Time domain simulations are used extensively to assess the availability of turret moored terminals for offloading operations. The availability analysis provides a key input when assessing the economical viability of a project. In this context, it was deemed important to perform a benchmark study. Three programs have been used: AQWA-DRIFT – an ANSYS...

Supervised by Chiang C. Mei. Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1987. Includes bibliographical references (leaf 255).