Underwater Technology
Vol 22
No 1
Summer 1996
A Personal View
An independent View of the Society
M Crawford
Technical Papers
Simplified First Order Motion Analysis
of a Moored FPSO
D J Smith
Abstract: This paper presents a simplified
method based on a barge shape, for predicting the first order
motion response of a typical moored floating Production Storage
and Offloading (FPSO) vessel. The technique is suitable
for use on a spread sheet and provides rapid optimisation for
any given vessel and environment combination. Results are
presented from a three-dimensional diffraction program showing
that a barge shape can be used to estimate the motions of a FPSO
at an earlier stage of the design process.
Dynamic Seals in HP/HT Wells
R Shepherd and A Stevenson
Abstract: Emerging completion technologies
are placing increased demands on seal systems required for
downhole use. The move towards higher production pressures
and temperatures (HP/HT) means that seal design could become the
limiting factor for the exploitation of HP?HT wells in the North
Sea and elsewhere. Current dynamic seal design practice is
not supported by a fundamental base of knowledge, although there
is experience and empirical data at existing operating
conditions. The basis for predicting seal behaviours under
conditions more extreme than those currently experienced is
therefore limited. For this reason MERL has designed and
built a new instrumented dynamic seal test facility to
investigate the behaviours and mechanisms of failure of seals,
under realistic conditions simulating downhole service.
The test facility that exists is unique in Europe and its
function is illustrated by reference to typical results.
Avoiding the use of Exotic Materials in
Pipeline Design
D H Demetriou
Abstract: The continued exploration and
development of deepwater offshore oil and gas fields presents
greater technical challenges to the pipeline engineer.
Such wells tend to produce very corrosive wellstream
fluids at high wellhead flowing temperatures. This paper
will examine aspects of pipeline materials selection based on
corrosion resistance requirements. A review of alternative
pipeline materials is presented, together with limitations on
the use of each material for corrosive service. Finally,
the paper will demonstrate how a re-evaluation of the
traditional predictive models for assessment of corrosion rates,
in wet CO2
gas pipelines, can avoid the use of
high alloy carbon steels, or exotic materials.
A Technique for Monitoring the
Settlement of Fouling Organisms at Exposed Subtidal Locations —
Technical Note
IS Thompson et al
Meeting Reports
Underwater Research and Discovery
M Breen, C Johnston and S Marine
Offshore Mechanics and Arctic
Engineering
DT Brown
Book Reviews
Remotely Operated Vehicles of the World
Reviewed by John Bevan
Anchor Handling Tugs and Supply Vessels
of the World
Reviewed by John Bevan
Survey Vessels of the World
Reviewed by John Bevan
Underwater
Technology
Vol 22 No
2
Winter 1996-97
A Personal View
The future is subsea but not us for
humans
Dr Rex Gaisford
Technical Papers
The Design and Evaluation of a
Phase-Steered Parametric Sonar System Intended for Sediment
Characterisation
JC Cook, AD Goodson, PA Lepper, B
Woodward
Abstract: The ultimate aim of the
European Commission's MAST-II REBECCA project was to study the
viability of characterising sub-bottom sediment structures
entirely by acoustic means. Part of the system developed
to attempt the realise this aim was a parametric sonar system.
The mode of operation was to insonify the sea bed at different
incidence angles, using a variety of transmitted acoustic
pulses, and subsequently to examine reflected and
forward-scattered signals. The paper describes firstly the
transmitting system designed and developed at Loughborough
University. It then presents the results of static
calibration tests in Lock Duich, Scotland and further results
obtained during sea trials on two French research vessels off
the coast of Brittany, when the parametric sonar array was
integrated into a two-fish with an attached hydrophone streamer.
The sonar transmits a phase-steerable primary beam centred at 75
kHz and generates in the water useful secondary signals at
typically 3 kHz to 7kHz, with a narrow sidelobe-free beam (2.5°
x 2.5°), at Source Levels up to 196 dB re 1
mPa at 1m at 5
KHz.
Weather and Climate Variability Since
Prehistoric Times and Recent Indications of Continuing
Fluctuations in the N.E. Atlantic
N Lynagh
Abstract: Weather and climate are in a
constant state of variation. The time-scales over which
these variations take place range from minutes to millennia and
even longer. Human experience of these variations spans
only a very short period of time. As a consequence, a
change which is actually part of a long-period variation about
the mean can easily be mistaken for a trend in the mean itself.
In recent decades significant variations in the wave climate of
the N.E. Atlantic Ocean have been identified. It is
important to try to identify whether these changes are a
variation about a steady mean or whether they are
indicative of a shift in the mean itself. An examination
of the varying climate of storm systems in the N.E. Atlantic
helps to provide an understanding of why the wave climate
appears to have changed.
Deepwater Geotechnical Investigations
in the Gulf of Mexico
JH Pelletier, EH Doyle and RN Dutt
Abstract: This paper discusses Shell
Offshore Inc.'s current deepwater Gulf of Mexico (GOM)
geotechnical investigation practice. The development of
the geotechnical investigation prognosis and its components are
outlined. The paper discusses the range of water depths,
site soils, platform types, investigation vessels , and in
situ tools that have been used. Both standard and
advanced laboratory testing schemes are presented and their
purposes discussed. The importance of integrated
geophysical studies for defining investigation scopes is
highlighted. The use of the data for the design of surface
and subsea development structure foundations and exploration and
production wells is reviewed. The Mars Tension Leg
Platform (TLP) site is provided as an example of an integrated
geotechnical investigation. Finally, the paper proposes
directions for advances and development in geotechnical
investigations and associated technology for the 21st century.
Meeting Reports:
Climate Change Offshore N.W. Europe ―
An Assessment of the Impact of Changing Meteorological and
Oceanographic (Metocean) Conditions on Offshore Activities
INL Gallett, D Thomas and A J Fyfe
Using the Marine Environment for the
Greater God
AG Senior
An Update on Subsea Tree Technology
SA Hutton and H Howells
Book Reviews
International Offshore Engineering
Reviewed by C Kuo
Titanium Alloys in Subsea and Offshore
Production Systems
Reviewed by WD Loth
Underwater
Technology
Vol 22 No 3
Summer 1997
A Personal View
From manganese nodules to Working Time
Directives
A Read
Technical Papers
Extreme Value Analysis of the
Structural Response of a Single Point Moored Vessel
J Bowers, I Morton and G Mould
Department of Management and Organisation, Faculty of
Management, University of Sterling, Sterling, FK9 4 LA, UK
Reports
Near Seabed Geophysics and Geotechnics: What can they do for
your next subsea pipeline project?
B Tollin
Towards 2000: Metres or Millenium?
J Sommerville and M Cook
ASPECT '96: Advances in Subsea Pipeline
Engineering and Technology
A Kyriacou et al.
Tax Pounds and Toxic Seas: Deep Water
Containment of Pollutants
INL Gallett
Book Reviews
Sea Change : A Message of the Oceans
Reviewed by DA Pilgrim
Dredging : A Handbook for Engineers
Reviewed by LJ Ayling
The Infernal Diver
Reviewed by RL Allwood
Underwater
Technology
Vol 22 No 4
Autumn 1997
A Personal View
The Marine Foresight Report
D Goodrich
Technical Papers
Report of the Marine Technology Foresight Panel Working Group on
Energy
D McKenzie
Introduction: The Marine Foresight Panel came
about in 1995 to represent the cross-cutting interests of the
Marine Markets as the sixteenth panel in the UK Government's
Technology Foresight exercise. The Technology Foresight
process was set up as a national consultation exercise to bring
together industry, academia and government to determine where
the country should invest its science, engineering and
technology spending.
In view of the
range and scope of technologies which underpin the marine
industries in the United Kingdom this Foresight Panel was made
up of five sub-groups, reporting to the Panel Chairman and
resulting in a Final Report made up of their findings.
This paper is the second of two sub-group reports to be covered
in Underwater Technology, selected for their interests to
SUT members.
This report summarises
the initial work of the Energy Sub-Group in identifying those
areas in the fields of marine energy where there is high
potential for innovative and economically significant
developments to be initiated, within the Foresight time-scale of
20―30 years, through research and applied technology.
Is Abyssal Seafloor Isolation an Environmentally Sound Waste
Management Option?
DK Young and PJ Valent
Abstract: This paper
discusses the waste disposal concept of environmentally
isolating industrial wastes (i.e. sewage sludge, fly ash from
municipal incinerators, and dredged material) on the abyssal
seafloor. Environmental acceptability of this concept is
compared with alternative oceanic waste management concepts of
containment and dispersion. Dredged material, containing
contaminants with high particle affinities enabling potential
toxins to be readily sorbed to sediment and be buried within the
seabed, is ideally suited for abyssal seafloor isolation.
Sewage sludge, with low bulk densities, is better suited for
disposal by dispersion. Fly ash, containing high levels of
heavy metals which can be mobilised under certain redox
conditions, is a poor candidate for ocean disposal.
Marine Biological Mapping for Environment Management Using
Acoustic Ground Discrimination Systems and Geographic
Information Systems
J Davies, R Foster-Smith and IS Sotheran
Abstract: Effective marine environmental
management requires base maps of biological resources.
Remote sensing techniques are one of the most cost-effective
methods of resource mapping. Sonar is the optimal method
of remote sensing the seabed in turbid, temperate marine waters.
Acoustic group discrimination systems provide a relatively
simple, low-cost method of sea bed mapping but are designed to
map the physical environmental variables of topography and
seabed type. The BioMar project at the University of
Newcastle-upon-Tyne has developed methods of analysing acoustic
data in conjunction with biological information to produce
biological resource maps. These methods utilise geographic
information systems (GIS). These methods are described and
illustrated with data from two case studies undertaken for the
UK Government conservation agencies.
Fuzzy Yaw Autopilots for Unmanned Underwater Vehicles Tuned
Using Artificial Neural Networks
R Sutton and PJ Craven
Abstract: This paper
describes the application of neuro-fuzzy techniques in the
design of autopilots for controlling the yaw dynamics of an
unmanned underwater vehicle. Autopilots are designed using
an adaptive-network-based fuzzy inference system (ANFIS), a
simulated annealing turning methodology, and a fixed fuzzy
rule-based approach. To describe the yaw dynamic
characteristics of an unmanned underwater vehicle and realistic
simulation model is employed. Results are presented which
demonstrate the superiority of the ANFIS approach. It is
concluded that the approach offers a viable alternative method
for designing such autopilots.
Reports
Report of the Marine Technology Foresight Panel Working Group
on Energy
D McKenzie
New Methods of Subsea Wellhead Control
W Andrews
Behaviour of Offshore Structures '97
DT Brown
Denizens of the Deep: The Marine Life of the Atlantic
Frontier
INL Gallett
Book Reviews
Regional Satellite Oceanography
Reviewed by DJT Carter
Sea Dumped Chemical Weapons: Aspects, Problems and Solutions
Reviewed by M Crawford
Oceanography
K Dyer
