ABSTRACT There have been radical changes in perceptions of global oil and gas market futures in the last ten years. These changes in expectations of reserves, demand, prices and supply sources have triggered revolutions in technological and commercial practices in the offshore business. These new concepts are designed to protect and enhance oil company profitability in their upstream activity, but they also bring daunting challenges for service and contracting companies and for their investors and shareholders. This paper looks at the reasons for these changes, the evidence of the pace of change, examines some of the consequences and explores where the changes may lead in the future. The evidence used to illustrate these themes is drawn from the work of Petrodata Research which has been carrying out analysis and forecasting in global offshore markets for more than 13 years New Wars, New Weapons The battle for shares of oil company capital spending in the offshore market in the decade to 2005 will be fought across a technological and contractual landscape radically different from the familiar terrain of the last 20 years. The winning companies will therefore be quite different too, whether they have the same names as the players of the last decade or not. It is no foregone conclusion that the leaders in offshore contracting in the 1970s and the 1980s will also be the main players in the year 2000. The evidence is that the market for new field development contracting which has already changed dramatically, will change further still and that the companies which dominated the business in the last ten years are finding it hard to adapt quickly enough and more difficult still to make money. If there is one single factor which is forcing more change more quickly than at any time in the last 20 years of offshore contracting, that factor is the oil industry's huge and very rapid achievement in squeezing much more oil out of every dollar spent during the last five years or so. The subsea revolution plays a big role in that achievement. The North Sea is the front line in that revolution but the changes are moving fast worldwide, especially in water depths of 70 metres and more. Indeed, production in very deep water is likely to spread beyong Brazil to the US Gulf of Mexico, to the West of Shetland play and elsewhere. The winning contractors which will lead the market through the next ten years will be those which follow and match the changing mix in capital expenditure on new offshore production systems. The capital spend profile of the 1970s and 1980s was shaped by fixed platforms and their topsides and their associated installation and hookup techniques and equipment. The profile of the winning contractors was naturally the same. The profile for the next ten year is different. There is a much wider spread of field development categories. There are many more projects, mostly much smaller in size, shorter in lead time and deliveries

ABSTRACT This paper reviews the results of the Technology for Unmanned Underwater Vehicles (TUUV) program. It compares the initial objectives as stated in the program's prospectus with the published principle results. The paper also reviews the status of each project with respect to the potential for commercialization of the research work. INTRODUCTION The TUUV program is join Marine Technology Directorate (MTD) and industry-sponsored research and development program managed by the MTD. The sponsoring companies are Rockwater Ltd, Shell UK Exploration and Production, DTI Offshore Supplies Office, Defence Research Agency, Health and Safety Executive, Mobil North Sea Limited, Lockheed Aeronautical Systems Co, Simrad Osprey Ltd. The program consists of 11 University research projects based at 5 universities with a total budget of approximately £14 million. The program started in 1992 and was completed in mid 1995. All the project are designed to further the development of unmanned underwater vehicles (UUV). The project falls into three broad categories, new project to investigate promising ideal, mid life project which require more investigation and well developed projects which need to be pushed nearer commercialization. This paper reviews the results of the project as reported in the Executive Summary Report ref(1) and compares them to the objectives as set out in the Research Project Prospectus ref (2). Initial Objectives The overall objectives of the TUUV program were based on a two-part technical brief Six typical missions Pipeline survery Offshore platform IRM Wellhead and Satellite Wellhead IRM Seabed Object Detection and Classification Seabed Construction Wet Salvage An operational cycle Lift off the deck of the support vessel Deployment through the splash zone Navigation to the work site Navigation around the work site Perform the work task Return to the recovery point Recover through the splash zone Land on the supply vessel Universities were invited to submit proposals aimed at improving the capability of unmanned vehicles in these areas 54 proposals were received, however restrictions in funding allowed only 11 to proceed. Comparison Of Objective With Results TUO1Techniques for the processing of side scan sonar from large data sets This program is designed to improve the collection and storage of many types of data. It is the continuation of work started under the Automation of Subsea Tasks (AST) Original Objectives To develop new techniques to process the large data sets obtained from sidescan sonar surveys of the seabed To establish a standard database of textures of the seabed from sidescan sonar surveys. The TUUV Program This project has achieved the first objective, and a data compression algorithm has been developed which compresses sidescan data with an average compression ratio of 100 1. The second objective was not achieved. However as in many research projects, several other objectives became obvious as the work developed. To develop algorithms for delineating sediment boundaries from sidescan data records. To ensure these algorithms are robust and operate in real time on IBM PC compatible machines

ABSTRACT In 1991, in a collaborative venture under the auspices of the DTI, GEC-Marconi developed a test-bed Autonomous Underwater Vehicle. In line with the tenets of the CRINE initiative this vehicle is currently being developed (through JIP funding) to undertake autonomous oilfield pipeline survey missions, with minimal weather dependence and without the need for surface support vessels. This paper reviews the available AUV sub-system technology and described the aims and activities of the current project. INTRODUCTION The North Sea represents a mature hydrocarbon production asset with an extensive infrastructure of major trunklines, interfiled pipelines and intrafield flowlines. The integrity of this vital hydrocarbon transportation system is monitored by the Operators through surveys specified by "in-house" procedures and statutory regulations. These surveys are currently executed by surface vessels deploying ROVs or towed instrumentation arrays. Over the last few years considerable non "oil and gas" related research effort has been expended to successfully develop Autonomous Underwater Vehicles (AUVs) for oceanographic data gathering on the continental shelf and in specialized military applications. This work (now aimed primarily at extended "cross ocean" missions in ultra deep water) continues, but the technological know-how generated could be adapted for the less onerous task of subsea hydrocarbon pipeline survey. In the spirit of CRINE (Cost Reduction Initiative for the New Era) a Joint Industry Project (JIP) has been initiated with the aim of defining, developing, testing and bringing to the market place an autonomous (free swimming) pipeline survey vehicle. By launching (and recovering) the survey AUV from the offshore platform (or pipeline landfall) the requirement for surface support vessels and associated weather downtime is eliminated. This provides an opportunity to achieve a substantial reduction in operating costs. The JIP itself is perhaps unique in that it is neither a paper exercise nor a high cost hardware development programme. The bas vehicle has been built and tested by GEV-Marconi Naval Systems Ltd., and is being made available to the project. Work will therefore centre on the attainable and specifically defined goals of optimising offshore launch and recovery, and navigation techniques, and selecting suitable data gathering instrumentation. The following paper details the project aims and activities and discusses possible future developments. Background And Rationable GEC-Marconi Naval Systems Ltd are the UK's leading naval weapons research and development contractor dealing primarily in advanced torpedo technology. In 1991, in a collaborative venture under the auspices of the Department of Trade and Industry, the company allocated substantial funds to initiate work on the design and construction of an Autonomous Underwater Vehicle to be used as a test-bed for oceanographic instrumentation packages for long range missions. The resulting vehicle system, ODAS (ocean Data Acquisition System, ref. fig 1), has been extensively tested and refined and is now available to be tailored to specific mission requirements. In bringing this technology to the offshore industry annual pipeline integrity surveys are seen as being a suitable "first step" task for the AUV systems.

ABSTRACT Within the next few years, the offshore oil industry will being seeking to exploit hydrocarbon reserves at depths inaccessible to saturation divers, and at which the welding processes currently in offshore use will not operate. Alternative processes exist for the water depth range 500 to 1000 metres, and these have been shown to be viable in laboratory trials. Further work is required to bring them to full operational status, and to integrate them with the wide range of other equipment required to carry out complete underwater fabrication procedure without diver intervention. Although alternative fabrication techniques exist, it is generally agreed that if hyperbaric welding can be shown to be reliable, and to produce acceptable joints, it will continue to be used by the offshore industry. At present, no facilities exist for hyperbaric welding research at depths significantly greater than 1000 metres. Cranfield is currently commissioning a 250bar research facility, which is capable of undertaking studies into the performance and properties of arc welding at pressures equivalent to a water depth of 2.5km. INTRODUCTION In general, most of the fabrication and repair of underwater pipelines takes place in Continental Shelf water depths, which are usually less than 200 metres. For these situations, manual welding techniques are used, with gas tungsten arc welding (GTAW) for root welds and hot passes, shielded metal arc welding (SMAW) being employed to fill the bulk of the weld. In the early 1980's, a requirement arose to provide a repair capability for pipelines being laid across the Norwegian Trench, an area of the North Sea in which the depth can approach 400 metres. It was appreciated that the physical capabilities of saturation divers became more limited as depth increased, and welding, as a skill requiring long term dexterity and concentration, was particularly vulnerable to this effect. It seemed unlikely that conventional manual welding techniques would produce consistently acceptable results at the increased depth of the Norwegian Trench. For the relatively simple weld geometries required to join pipes, automated orbital welding systems were developed. Although several of these exist, developed by Sub Sea international (OTTO, Lyons and Middleton, 1984), Comex (THOR 1 and 2, Blight and Baylot, 197) and Statoil (PRS, Styve and Andersen, 1994), they have many similarities. All use some form of tractor, controlled from the surface, crawling round a track installed on the pipe, and upon which is mounted a welding torch and manipulator, consumable fees unit, and weld pool viewing system. All utilize the GTA welding process, with filler addition. The task of the saturation driver is to install and remove these systems, and to replace consumable spools and tungsten electrodes as required. Such systems have been used for the past ten years, generally successfully, and are currently being considered for operations at shallower depths, and for an increasingly wide range of pipeline materials (Malone and Ralston, 1992). Although the pace of development of offshore hydrocarbon reserves has been irregular, and greatly influenced by the low price of crude oil, it is generally agreed

ABSTRACT Snap Lay? is a method of laying rigid steel pipelines using mechanical connectors to join spoolpieces together. This paper outlines its applications including the laying of pipe from a barge or constructions vessel, laying from an drilling rig and laying pipe by snapping spools together on the seabed. Finally the paper will review the most recent installation of two kilometers of twenty four inch diameter pipe on the Harding field for BP. INTRODUCTION Snap Lay? is a pipelay system which can fundamentally changes the way in which oil field are developed because it offers new opportunities in the configuration and installation of pipelines. An alliance to promote Snap Lay? was formed by SubSea Offshore, Hunting Oilfield Services and Uglands Offshore which offers a complete installation capability SnapLay projects will normally be led by SubSea Offshore. The Merlin? Connector The heart of the Snap Lay?system is the Merlin? Connector. The connector has been in use for over twelve years primarily in conductor and casing applications but it was also used as the connection medium for the tendons for the Shell Auger and Mars TLP's in the Gulf of Mexico (Figure 1) the Merlin? is a box and pin type of connector with a series of parallel teeth on the outside of the pin and a corresponding set on the inside of the box (figure 2) (It should be noted that these are not threads and no rotation is required for make-up). Each component has a nib and recess which form the sealing elements. The connector is currently produced in sizes ranging from 16 to 48′ but larger and smaller diameters are possible. There are over two thousand Merlins?in use and there is an exhaustive history of testing to draw on (figure 3 shows a pipe test piece with an early Merlin type connector being tested and demonstrating that the connector is stronger than the pipe). Connector Operation The connectors are welded onto the pipe spools as shown in Figure 4. The method of make-up is shown in Figure 5. The pin is inserted into the box until the nibs on both components engage on the corresponding profiles prior to the entry into the sealing recess. The teeth are configured such that they will not engage until the final make up position a makeup clamp is fitted around the two connector components and a hydraulic injection line is installed. Hydraulic fluid is injected into the void bounded by the two nib/profile seals. The effect of this injection is to compress the pin and expand and with an axial force of up to 400 tons the two components are forced together until the nibs engage in the recess. The hydraulic pressure is then released and the teeth engage. This makeup sequence is fully reversible. Once made up clamp and hydraulic line are removed and plugs fitted. The connector offers four metal to metal seals between the bore of the pipe and the surrounding environment with each nib forming a metal to metal seal on its inner and outer faces.

ABSTRACT The need for clear communication between diver and topside is obvious, safe practices depend on good communications as do efficient operations and effective response to an emergency. The requirements of communications systems have only recently been formalized. The rationale behind the design of communications tests are specific problems of helium speech are discussed. Tests made on commercial diving installations show that all parts of the system are important. No matter how good the unscramble good performance may sometimes only be achieved by using it in conjunction with a particular microphone. Results of tests will be presented to demonstrate this and to demonstrate that the commonly held belief that speech is more intelligible without the unscrambler may sometimes be true. The acoustic characteristics of the space from which the sound is being transmitted influences the intelligibility and two identical systems, used in different chambers, give very different performances. These results suggest that investing large sums of money to design new unscramblers may be wasteful and much smaller investments, which produce intergrated systems to suit the particular space in which each will be used, will give much greater improvements in intelligibility. INTRODUCTION It has become accepted practice to evaluate diver communications systems using a Modified Rhyme Test (MRT). The MRT is a modification of the Rhyme Test devised by Fairbanks (1958) and was suggested and evaluated by House et al (1965) for use where it is not possible to devote a great deal of time to training the readers and listeners. A further modification, that of Griffiths, is the format used by the industry. The MRT of house et al is widely accepted as a means of evaluating speech communication and was accepted by the American Standards Committee for Acoustics (1989) The usual procedure is to play pre-recorded test tapes through each communications link and to use a team of listeners to score the tests "live", "on location" in the control room. This is carried out in the presence of an independent observer who marks the score sheets and calculates the average intelligibility for each link. The presence of helium in the breathing gas distorts speech and unscramblers are used to restore this distorted speech to a form which can be recognized by the listener. Over the years a great deal of time, money and ingenuity has been expended to improve the design of unscramblers the experience gained from testing communications systems in recent years suggests that the main problems do not now arise from the performance of the unscrambler in that those available make a good job of unscrambling helium speech. The balance of the evidence seems to indicate that distortions generated by the rest of the communications link, which the unscramblers were not designed to correct, are the main cause of loss of intelligibility. Communication Testing Rationale Behind The Design of Communications Tests The earliest suggestion for intelligibility testing was made by Campbell in 1910 for testing the new telephone system of communication.

ABSTRACT A review of the advances made in the Control Depth Tow Method (CDTM) of installing pipeline bundles, including an outline of the design philosophy, the way in which the design was implemented and a summary of the experience gained during the installation. The paper described the changes to the CDTM process which reduced the size of the fleet required to install the bundle and outlines the way in which parts of the installation process were achieved remotely, without the use of divers or ROVs. Reduction in installation cost and improved operational flexibility are also highlighted. INTRODUCTION Rockwater has a long history of building and installing pipeline bundles in the North Sea using the well known CDTM. As with all technologies it is continuously developing, rising to the challenges of competition and continuing low oil prices. Rockwater builds bundles at the Wester fabrication facility located near wick in Caithness. The site is 66 km in length and is equipped with fabrication shop facilities and two rail tracks. The bundle is manufactured from carrier pipe, flowlines, service lines and umbilicals, and is launched from the railway track into Sinclairs Bay. After a series of engineering checks the bundle is towed to the installation site using CDTM. The Cyrus bundle is designed to carry oil and services between the Andrew and Cyrus fields. The bundle is approximately 65 km long and consists of a 10″ flowline insulated with 2″ of low density PU foam, which in turn are protected by a 14″ sleeve pipe. This combination provides very effective low cost pipe line insulation. The bundle also contained a 4″ gas lift pipe, a 2″ service line, 9 hydraulic control tubes, 2 electrical power cables and 2 electrical signal cables. Several developments of the standard bundle launch, tow and installation methodology were used on the Cyrus project. This document highlights these developments and the reasons for their use. Design Philosophy In a conventional CDTM tow the depth and the shape of the bundle are monitored using transponders which communicate acoustically with a survey vessel travelling alongside the bundle. Limitations in acoustic range in the medium frequency band (MF) mean that for a bundle longer than 45 km two survey vessels are required to monitor the bundle during tow. Thus a typical towing fleet for "long" bundles consists of One or more leading tugs to provide the forward towing force Trailing tug to provide the back tension Two survey vessels stationed alongside the bundle to monitor bundle depth One patrol vessel to prevent other vessels from crossing the bundle during tow The Cyrus project made use of an internal "data highway" to transmit data from depth sensors positioned along the bundle to any transponder on the bundle. This decision decoupled the depth and shape monitoring from the survey vessels, since either the leading or the trailing tugs could monitor the depth using acoustic telemetry. It also removed the requirement for one of the survey vessels

ABSTRACT The removal of the Fulmar Single Anchor Leg Mooring (SALM) Buoy was carried out by Stolt Comex Seaway Ltd within a ten day period during July 1994. The removal of the SALM was achieved by cold cutting the buoy from its base utilising underwater Jet Abrasive Cutting (JAC) equipment. The cutting was achieved by mixing a water/grit slurry on the surface and pumping it through a hose to a nozzle positioned within certain parameters from the face of the steel being cut. The nozzle was manipulated to achieve the required cutting line by utilising a number of track systems developed specifically for the project. The objective was to remove the SALM in a safe and controlled manner. The buoy had In excess of 2000T upward buoyancy when attached to the seabed so once a certain amount of cutting was completed the buoy broke free Safe access and prediction of breakaway were all considered when deciding on the cutting sequence A safety case was prepared by Shell UK Exploration and Production for the work. A total of 24 metres of 65mm to 75mm thick steel plate was cut using this cold cutting method. The result of the cutting process was the ultimate breakaway of the Fulmar SALM Buoy from its fixed seabed base Once the SALM was released and was free floating it was towed to a storage site In a Norwegian Fjord. INTRODUCTION In November of 1993, Shell Expro contracted Stolt Comex Seaway Ltd to remove the Fulmar SALM Buoy from its anchored position in the Fulmar field. This work formed part of the overall decommissioning of the Fulmar floating storage and offloading facility The Fulmar SALM Buoy itself consisted of a rigid buoy structure connected to a base on the seabed by a universal joint arrangement. When the SALM Buoy was operational, a topside articulated rigid arm permanently moored a Tanker Storage. Vessel Prior to the removal of the SALM Buoy by Stolt Comex Seaway the rigid arm and tanker were removed by others, leaving only the top structure of the SALM Buoy visible above the surface (See Fig 1). This paper describes the application of Jet Abrasive Cutting for the SALM Removal Works. APPLICATION OF COLD CUTTING Equipment Design Methodology During the pre-engineering phase it was established by Shell Expro that following upon the removal of the rigid arm assembly, a net upward buoyancy of around 2000 tonnes would be acting on the SALM Buoy Base. This meant that during the process of removal of the Buoy these forces would at some point cause the buoy to ‘break free’ from its seabed base. The design for removal had to take this into consideration and it was imperative that the possibility of the SALM Buoy only being partly removed and therefore greatly weakened to the elements was eliminated by a safe, reliable and predicable system of removal. During the conceptual engineering phase for the removal of the Fulmar SALM Shell Expro considered various approaches for release of the buoy from the buoy base

ABSTRACT This paper briefly discusses Digital Terrain Modeling (DTM) techniques. Then, by presenting applications of DTM to Route Optimisation and Presweeping, it is suggested that over-engineering, normally introduced as safety factors to allow for limitations in the mapping of seabed topography, could be reduced with consequent savings In capital costs Similarly, it is shown that DTM-enhanced engineering techniques can be applied to trend monitoring of Pipeline Survey data, and that this approach can reduce rectification and its associated operating costs Indeed, if DTM-enhanced engineering IS applied through the life of a pipeline, this can have additional benefits at the end of life The paper closes with a discussion of future developments. INTRODUCTION All operators and offshore contractors are continually striving for two things reduction in costs, and improvement in safety In many ways it might appear that these two aims are mutually exclusive However, by applying DTM techniques to enhance subsea engineering, it is possible to reduce overall costs while maintaining and even improving the level of safety These aims are achieved through a better comprehension of the operating environment Unlike the civil engineer on land, the subsea engineer cannot step back and observe the lay of the land, or the details of the location of a subsea structure The range and field of view of a subsea video camera is very limited so that it is not possible to reference one feature to another, or to appreciate gradients of the sea floor. The real time output of echo sounders and sonars does not generally give an adequately comprehensive picture This is not a limitation if the seabed is flat but, in an area of rugged terrain, the subsea engineer must rely on visualization techniques The resulting unknowns have been compensated for by the application of safety margins or factors In this way safety has been maintained, but almost certainly at the expense of over engineering. However, this deficiency can be mitigated by the ability to visualise the subsea environment by graphical models The value of this approach depends upon two main criteria the quantity and quality of the input data, and the agility and speed with which these can be assembled into a usable graphical form, and then manipulated. The use of a Digital Terrain Model to visualize the seabed means that submarine pipelines can be designed much more accurately and subsequently monitored throughout then lives Indeed, it is possible to consider five stages In the life of a submarine pipeline design, installation, operating life, life extension, and abandonment This paper demonstrates how DTM techniques can be utilised to enhance engineering during all these stages DIGITAL TERRAIN MODELLING The Admiralty Chart can be seen as a form of seabed terrain model It shows depths and contours and the positions of seabed hazards It also presents information on the seabed material It IS actually quite limited, however, so far as seabed modeling IS concerned because, until very recently, depths were obtained from single readings taken at intervals along survey lines whose positional accuracy was limited

ABSTRACT This paper reviews proposals by the Health and Safety Executive for changes to the General Certificates of Exemption Issued under the Delving Operations at Work Regulations 1981 and current attitudes to the use of Nitrox in inshore commercial diving GENERAL CERTIFICATES OF EXEMPTION By the introduction of the Diving Operations at Work Regulations 1981 (DOWR), which covered all commercial diving operations, various groups of divers which had not previously been regulated under the Diving Operations Special Regulations 1960 came within the regulatory net In particular DOWR brought archaeologists, journalists, scientists and instructors of amateur divers within the scope of regulations For these groups probably the most onerous and controversial requirement in DOWR was the requirement for all divers "at work" to hold diver training certificates (Regulation 7(l)(a)) One of the main underwater archaeological projects of that time was the Mary Rose Project and archaeologists working on that project took the lead the In opposing the introduction of DOWR The main thrust of their objection concerned the difficulties presented by DOWR for them to include amateur divers In their work Because of financial constraints, underwater archaeology greatly depends on the activities of amateur divers to supplement the work of a few professional underwater archaeologists The result of their objection was the granting by HSE of a Certificate of Exemption from DOWR for archaeological diving This was immediately followed by the Issue of Certificates of Exemption for journalism, diving for the purposes of scientific research and the "commercial" instruction of amateur divers The latter is a slightly different category of diving operation and is dealt with separately in the paper The Certificates of Exemption for archaeologists, journalists and the instruction of amateurs dating from 1981 are still in force but the Certificate of Exemption for diving in connection with scientific research has been revised a number of times - most recently in 1988 When the original Certificates of Exemption were Issued HSE undertook to review them at an unspecified time In the future In the time since they were issued, a number of problems have arisen which the Health & Safety Executive (HSE) now consider collectively to be of sufficient importance to justify their review These problems Include the scope and definition of the diving operations covered by the Certificates of Exemption changes to particular regulations in DOWR from which exemption was granted - for example Regulation 5 which has been extended by recent amendments to DOWR, problems In enforcement and changes in diving technology HSE also considered that dependence by employers on the use of recreational training and qualifications when dealing with an occupational hazard, such as is the case with diving scientists, could be considered not to be In keeping the spirit of Section 2 of the Health and Safety at Work Act in the field of commercial instruction of amateurs, problems have arisen with the training of employees and with amateur divers being taught non-diving topics such as underwater photography

ABSTRACT Lord Cullen's report on the Piper Alpha disaster docs not recommend a mandatory requirement for all hydrocarbon pipelines to have subsea isolation valves(SSIVs) However, the requirement of SSlVs will be determined through a Formal Safety Audit This paper briefly reviews the impact of the Cullen report on the pipeline system design and the requirement of SSIVs including preliminary proposals to dispose off the mapped hydrocarbon Inventory An overview of the SSIV system design identifies the cost effective approach without affecting the SSIV reliability After identifying testing, inspection and maintenance requirements, the paper discusses their impact on the design Finally, a conceptual design of a maintenance frame is presented which should help In reducing diving time during SSIV maintenance. INTRODUCTION Unfortunate events In the North Sea over the past few years lead the U K Government to review safety policies and practices of North Sea operators and regulatory bodies As a result of this review, Statutory Instrument No 1029 was introduced which makes it mandatory for all offshore installations which Import or export hydrocarbons to incorporate Emergency Shutdown Valves Into the risers at locations above the splash zone These valves arc required to have a positive safe control system to close the valves which detects and responds to an emergency There are, however no mandatory requirements for pipeline operators to incorporate subsea emergency/isolation valves The report by Lord Cullen following the Public Inquiry Into the Piper Alpha disaster makes comprehensive recommendations for improving overall safety of North Sea installations The whole safety process should start at the conceptual design stage by way of a Formal Safety Audit (FSA) and finally lead to a Safety Case which also includes safety management systems The inquiry looked Into the hydrocarbon pipeline operations and makes certain recommendations The Cullen report endorses Statutory Instrument no 1029 and docs not recommend a blanket requirement for subsea isolation valves(SS1Vs) The need of such valves would depend upon the Safety Case developed for each offshore installation Although neither the Department of Energy nor the Cullen report spell out mandatory installation of SSIVs, it is expected that most pipelines transporting gas and many transporting oil will be fitted with some form of barrier system Many new and operational pipelines have already been fitted or planned to be fitted with isolation valves The purpose of this paper is to briefly review the Impact of the Cullen report on the pipelines system design and to identify situations where SSIVs can lead to an improvement In the safety of the pipeline systems and hence that of the installation and the personnel working on oil Some modifications to riser design have been identified in this paper which would lead to rapid evacuation of the product, particularly the gas, trapped between the SSIV and the riser topsides ESDV during an emergency shutdown The paper presents a brief overview of the SSIV design and associated control and protection systems An Important aspect of the design should be its implicitly without sacrificing the integrity and operability

ABSTRACT This paper looks back to the early development of dynamically positioned vessels, showing how a system of suitability and safety assessment has been developed. The applications of DP have spread to a wide range of operations, and as the vessels and the systems have become more sophisticated the methods of suitability assessment have changed little, and up to now have been based upon a combination of charterers requirements and specific guidelines. The established means of assessment takes the form of a DP audit and trial, this is not a standard assessment throughout the industry, and In many cases does not take fully into account the suitability of the vessel for the work proposed, only it suitability as a dynamically positioned vessel. The current situation gives a great deal of scope for improvement and proposals outlined In this paper will give details of how a standardised system of suitability and DP safety assessment can be developed and introduced. 1. INTRODUCTION - Past to Present Dynamic positioning systems were originally developed In the 1960's as a means of position keeping for drill ships, operating In deep waters and where it was not desirable to have mooring systems deployed. These early systems were normally developed as single computer, non-redundant facilities which In the event of a single failure would normally result In the loss of position. A large number of DP vessels at the time were not purpose built and were often converted from cargo vessels no longer fit for their purpose. As a result the DP systems which were installed had to be adapted to the design of the vessel, inheriting some of the problems which the original hull shape would produce. A major difference between a cargo ship and DP vessel is the fact that the hulls are designed for different purposes, one is designed for high speed and least resistance, whereas the other is designed to remain stationary with the minimum amount of roll, pitch and heave. So it can be seen that from the early development of these vessels the best potential of DP system was not being harnessed. Hybrid vessels were being produced to carry out completely new work, under conditions which were highly demanding and potentially dangerous, yet the vessels were not intended nor fully tested for the purpose proposed. During this early period, DP audits and trials were not fully developed lf at all used. As incidents occurred and more was learnt about potential hazards and failures of the systems, the need for regular audits and trials of vessels was identified. The real need for these audits and trials was only really recognised when dynamic positioning was to be used for the station keeping of dive support vessels. Prior to this development, DP vessels had only really been involved in open water drilling operations where the effects of DP failure were, at that tune, feat to be minimal and insignificant in comparison with potential drilling hazards.

ABSTRACT In this paper Seaway's development project "Underwater Support Vessel for the 1990'ies" is described The vessel is being armed for both the diving and the ROV/ROT market The main characteristic of the vessel is presented, as well as the main topics being studied In the project Further, the following systems have been described more In detail, which partly already are in operation on existing vessels A new concept for hyperbaric diving system (patent pending) The concept consists of 8 vertical identical amber cells configured In a circle, and a turret-based handling system for the bells The DIVEROV concept This diving assisting vehicle, based on a standard ROY has now been In operation over one year The DIVEROV is flexible in the sense that it also can function as an advanced ROV for stand-alone tasks The module handling system now In operation on the DSV "Seaway Condor" This system incorporates both active and passive heave compensation for safe and efficient installation and retrieval of modules on subsea production systems 1. Introduction The development project "Subsea Support Vessel for the 1990'1es" was started In 1988 In order to coordinate our development efforts within several areas related to diving and ROV operations The aim has been to provide results from the different development areas In such a form that they can be applied to specify Seaway's underwater support vessel and work procedures for the future Some sub-projects have already resulted In systems and methods In operation on our existing vessels Primary functions for the vessel have been defined as follows. Diving related to IMR, construction work and contingency, especially for deep water diving ROV-operations related to the diving operations and intervention work where the ROV is used as a stand-alone vehicle Also module handling, well services and laying of cables and flexible flowliness have been defined as functions possible to adopt to the vessel 2. Subsea Support Vessel - Main Characteristics The following main characteristics/requirements have been defined for the vessel Mono-hull vessel, approx 100 x 20 m Diving system and other equipment dimensioned for state of the art diving to 450 msw, and optimized for diving to 350 msw (continuous diving possible). Deck area min. 800 m 2 Lifting capacity min 150 tons, active heave compensated (We are challenging the crane manufacturers to produce a 250 tons crane with same weight and dimensions) Accommodation for min 100 persons Hell-deck Two diving bells, also to be used simultaneously Air diving to be arranged for Work moon-pool min 7 x 6 m Two ROVs on board One for observation purposes and one advanced work-ROV with diving assisting capabilities (DIVEROV, ref Ch 5) Weather criteria for operation of vessel min 40 knots wind and 1, 5 knots current Transits peed min 12 knots Dynamic positioning system to fulfill requirements from authorities and clients as a minimum Active stabilization/compensation heave and rolling movements to be arranged for

ABSTRACT Sonsub North Sea Ltd IS a part of the Sonsub group of companies which has been involved in the application of remote systems technology to the subsea environment for a number of years. Primarily, Sonsub has been supporting the various requirements of the Offshore oil and Gas Exploration and Production industry. The use of robotics and other remote systems technology to successfully complete work tasks In the subsea environment, has presented challenges that have required an innovative approach to the use of telerobotics. Remotely Operated Vehicles (ROV's) are a form of robotics that have been utilised In the Offshore oil and Gas Industry since the early 1970's. However, until recently, their use has been restricted to observation and light manipulator work, utilising a variety of rate feed, spatially correspondent or tactile feedback manipulator systems. The Challenge remains to develop systems that have the ability to carry out human equivalent tasks presently performed by divers, thus enabling personnel to be removed from this hazardous environment. There are numerous difficulties to be overcome In meeting this challenge and this paper addresses a particular philosophy and methodology adopted by one company to service the needs of its customers. The Problems Taking telerobotics and remote handling technology into the subsea environment presents its own unique problems. The most obvious problem is ensuring that all electric, electronic and mechanical components are suitably protected against seawater and the pressures encountered when working at depth. Other less obvious, but equally critical problems related to the operating environment are as follows. Sea Surface Conditions This affects the launch and recovery of the relevant ROV systems and can cause considerable delay to operations whilst waiting for weather conditions within the system's launch and recovery limits. If work IS taking place from a floating vessel rather than a fixed offshore structure, unfavourable surface conditions can also have a dramatic effect on the station-keeping ability of the vessel. The need to carry out repair and maintenance to quite sophisticated electronic equipment on the deck of a heaving vessel In a severe storm, can challenge the skill and patience of the most qualified and experienced Technician. Ocean Currents The business end of an ROV system IS basically a vehicle which IS able to "fly" through water on the end of a control tether or umbilical carrying all power, signal and data conductors. An ROV is flown In a similar fashion to a helicopter, In that it IS free to move In all planes and has the ability to hover. The ROV IS subject to prevailing ocean currents as a helicopter is subject to prevailing winds. One major difference IS that the helicopter pilot has the advantage of "presence" and a feel for the conditions affecting the machine. The ROV pilot does not have this added dimension and can only fly and operate manipulators by vision with limited assistance from tactile sensors. It IS this lack of direct "presence" or "feel" that can make the performance of manipulative tasks extremely difficult.

ABSTRACT The recent trend toward Diverless intervention in the Offshore Industry has resulted In the development of remotely operated variants of a number of basic Items of equipment. TRONIC LTD In co-operation with SUB SEA OFFSHORE are currently engaged In the manufacture and test of an ROV Mateable connector based on existing technology where possible. The significant criteria addressed during the programme include tolerance to misalignments In various planes, rough handling, ease of assembly, and repeatable electrical properties to name but a few. The project is seen by the participants as on-going and a number of improvements have already been identified as being desirable In the flush product. 1. Introduction This paper is intended to provide an overview of the progress to date In the development of an ROV mateable connector. The programme is still In its early stages and, whilst significant features have still to be proven by long-term testing, recent tests have established the basic soundness of the design. The project began In December 1990 following initial discussions with Sub-sea Offshore. Whilst the basic requirement for diverless systems has been long established and was the stimulus behind the replacement of manned submersibles with ROVs In the late 1970's, it is only within the past 5 years that the design of conductive couplers has progressed to a stage where sub-sea mating is achievable with consistency. Whilst sub-sea mateable connectors existed prior to 5 years ago, In general they were unable to provide respectable and repeatable results or lacked the considerable robustness required to withstand handling by ROV. Additionally, none of the existing connectors were designed with 20 year+ immersion In mind, being either Neoprene moulded or constructed from unsuitable materials. The design, therefore, needed to bring together the features of several basic connector types, and to Introduce the robustness and tolerance to mis-handling inevitable with remote connection. In addition to the improvements achieved In connector design, certain other parallel developments had to take place to allow the requirement to be addressed. The most significant of these is the establishment of versatile handling systems, manipulators, tools etc, to allow the precise connection and disconnection of couplers (both hydraulic and electrical). Also of great importance to the project is the development by various ROV manufacturers of docking systems which can reduce the necessary dexterity of manipulation and increase the mating force available. Two separate approaches to remote connection are to be considered: Provision of ‘Stab Plates’ to enable connection to be made concurrent with equipment installation subsea. Provision of fixed connectors on one half of the structure with the mating being carried out by ROV following installation of the remainder of the equipment Whilst both systems have their merits and limitations, it was considered that, notwithstanding the necessity for ‘Stab Plates’, it was the ROV mateable connector that provided the most versatility. The perceived limitation of the ‘Stab Plate’ system is that, as it forms part of the structure being assembled, without careful design the coupling can be subject to high, non axial, mating forces and approach rates.

ABSTRACT The current classification of the decompression disorders, from which our diagnostic" labels" are derived, has shortcomings In particular, it requires the diagnosticiation make difficult decisions with respect to the location of presumed neurological lesions and the mechanism of the disease process It is now recognised that In the great majority of clinical settings, these decisions are virtually impossible to make with certainty In addition, it is considered that the dichotorny between ‘Type 1’ decompression sickness (DCS) and ‘Type 11’ DCS is artificial Each group contains a variety of conditions within known commonality of pathophysiology, it is widely recognised that symptoms from the two categories may coexist and that ‘Type I’ may progress to ‘Type 11’ The consequences of these shortcomings are that treatment algorithms are applied inconsistently, the epidemiology of these conditions remains obscure and occasionally, cases are managed inappropriately A solution is to abandon the current terminology In favour of a descriptive system In this presentation such a system IS proposed It IS considered that the adoption of such a system will lead, through better understanding, to improved management of the decompression disorder 1. INTRODUCTION The current means by which we classify decompression sickness dates back only 30 years to the experience gamed during the construction of the Dartford Tunnel in London Goldinger a1 [I] proposed a system for decompression sickness based upon perceived severity of the cases which arose In the cases on workers employed In the construction of the tunnel Only symptoms considered sufficiently severe to bring the man back for treatment' were considered to be decompression sickness They divided the cases Into two types Type 1, or simple ‘bends’ and Type 11, which were more serious or complicated cases which displayed vertigo (a spinning sensation), shock, paralysis, epigastric pain and shortness of breath Their system is st111 in use today essentially unchanged Traditionally, decompression sickness has been distinguished from the barotraumata and a summary of the current classification of the decompression disorders is presented In Table 1 TABLE 1 The present classification of the decompression disorders (after Elliott & Kindwall [2] and Farmer [3]) (Available in full paper) 2. Problems with the Current Classification The deficiencies and consequences of this classification have been reviewed previously [4] In summary, it requires the diagnostician to make difficult decisions, particularly where the nervous system is involved These Include determining the location of the lesion (e g "cerebral" or "spinal cord") and the mechanism of Injury (e g "decompression sickness" or "arterial gas embolism") At a recent Undersea and Hyperbaric Medical Society Workshop [5] it was recognised that In the great majority of clinical settings, such decisions are virtually impossible to make with certainty The consequence of this is that the existing diagnostic "labels" can not be applied rigorously As a result, treatment algorithms are inconsistently applied and communication between divers, physicians and medical researchers is compromised The existing dichotomy between ‘Type I’ or mild decompression sickness (DCS) and ‘Type II’ or serious DCS is spurious

ABSTRACT A new air decompression table has been developed for a dive to 40 msw for one hour, which employs a switch to a helium and oxygen mixture and oxygen during decompression The safety of the table has been validated using two types of ultrasonic monitoring 1. INTRODUCTION The problem of neurological decompression sickness In the air range has now been acknowledged In the UK and action taken to limit exposures to both compressed-air and nitrox mixtures[1] However the restrictions applied to in-water and surface-decompression air dives severely limit the useful work that can be done They also force more dives to be undertaken In order to complete the same amount of work increasing the number of dives Increases the risks from hazards other than decompression sickness [2] About half of all the diving fatalities in the oil and gas Industry have been related to surface-orientated diving Fortunately this has led to the successful development of transfer-under-pressure techniques in the air diving range Unfortunately, dlving on air well within the current limits as not guarantee that subtle neurological damage will not occur and, from an examination of the data there IS no safety margin The recommended limits for in-water decompression only slightly exceed the no-stop decompression curve for air dives However even adherence to the no-stop decompression limit doses not provide protection against neurological decompression sickness as the case of a diver who developed symptoms after a dive of 30 minutes at 30 fsw has demonstrated [3] A second problem is that the therapy of decompression illness, especially In the air range, is unsatisfactory In 1964 it was found that the air therapy tables recorded a failure rate of about 46% In the treatment of serious decompression sickness [4] The minimal-recompression oxygen breathing tables USN 5 and 6 were Introduced to solve this problem In 1965 It was soon recognised that oxygen at an equivalent pressure to 18 msw (60fsw) may paradoxically cause deterioration of a diver suffering from decompression sickness and this was recorded In the US Navy Diving Manual released In 1970 Both human and experimental studies indicate that there may be an irreversible component of severe dysbaric illness Currently, therefore, the Industry has both unsatisfactory working procedures and Inadequate schedules for therapy Compressed-air as a diving gas has been limited to 50 msw (165 fsw) by UK legislation, because of decompression sickness, but because at greater depths narcosis becomes significant Clearly, because it IS inexpensive and the diving equipment needed IS simple, many would st111 prefer to retain compressed-air In shallow-water diving However, it can only be retained if the problem of decompression sickness can be solved 2 Decompression Sickness and Decompression Tables The risk of decompression sickness was recognised by Bert In 1875 [5] to be due to nitrogen being released from solution that is, gas phase, due to super saturation He observed bubbles In the blood from a severed jugular vein in a dog following a decompression

ABSTRACT Photogrammetry has been In regular use since 1980 to produce three dimensional measurements underwater, for a variety of tasks The paper will briefly summarise the history of The technique, from its inspection orientated origins to the latest engineering related, deep water, ROV surveys, In order to analyse the strengths and weaknesses of the technique This analysis will Introduce the technological Improvements, leading to the satisfactory of market demands, that can be made possible with advancing technology The development of Real Time Photogrammetry, from the feasibility study to offshore trials, will then be introduced, emphasising the enormous possibilities of the technique and its component technologies electronic still Imaging, digital Image data transmission and storage, real time and still stereo viewing, and near Instant three dimensional measurements of complex objects The by-products of the development will also be Introduced, which Include total electronic reporting systems and the database controlled replay of visual data within a networked computer system, with suggestions as to how these could influence structural and pipeline Inspection, as well as engineering surveys In today's, as well as tomorrow's, world 1. INTRODUCTION 1.1 What is Photogrammetry? Photogrammetry IS a visual imaging technique for the acquisition of accurate three-dimensional measurements without contact with the subject Photogrammetry IS not a new technique, and has been In use for more than 100 years for the compilation of maps from aerial photography, for topographical surveying and for industrial uses, such as the quality control of large castings 1.2 Why isit used Underwater? Underwater Photogrammetry provides a fast and cost effective method of obtaining precise three dimensional measurements, for Inspection or engineering purposes It is necessary only to photograph a subject with a pair of photogrammetric cameras, or with a single photogrammetnc camera from two or more camera positions, in such a way as to achieve stereo coverage, to allow accurate measurements to be taken from the photographs It is a non-contact technique, and so there is little or no contact or Interference with the subject It allows measurements of subjects that are difficult to measure by conventional techniques, because of their shape or position It uses separate data acquisition and data processing phases and so it keeps underwater operational time to a minimum Its use is not complicated by a more complex shapes, for example lf many measurements are required to accurately define ihe shape of Impact damage which Included multiple Impacts, tears etc Total effort does not Increase proportionally with the number of points to be measured The analysis process is select we, and so can be tailored to the exact requirement of the application, even though the information density stored on photographic film is enormous The information can be stored archivally on the photographic film, to be extracted, or redefined, at any time The information may be presented In many forms as discrete measurements, sections, contours, plan and elevation drawings, isometrics, contours etc, to best suit the exact requirements of the end user

ABSTRACT This paper provides a discussion of the many points which should be considered when planning the engineering aspects of subsea development wells. The multi-discipline Issues In a subsea project are presented together In order to emphasise the requirement for effective project management and close teamwork. Drilling activities Including well design and rig selection are considered along with downhole completion design. This Includes the differing requirements of exploration wells and development wells with respect to subsequent well utilization. The requirements of the subsea completion, installation equipment and subsea facilities and their Impact on other well design Issues are presented. Recent industry efforts on subsea equipment standardization through API 17D and other North Sea initiatives and the potential for further industry standardisation are discussed. The paper should form a useful reference for those Involved In subsea projects by way of highlighting the Issues which must be considered, without always presenting solutions. Information has been drawn from many references reflecting primarily North Sea operations In addition to the author's own experience. INTRODUCTION The Issues presented are arranged under the following seven headings; Exploration and development well design Issues, rig selection, downhole completion, subsea completion, subsea facilities, standardisation and project management. Subsea well production technology is the theme for the paper and it is Intended to compliment Reference 1 which concentrates on drilling related subsea development well Issues. The nature of a subsea development implicitly involves many disciplines and it is essential that from the earl lest planning phase the potentially conflicting requirements of all the disciplines are taken Into account. This paper presents these Issues In order that they can be considered by personnel Involved with subsea projects and together can form a coordinated approach to production technology for subsea development wells. 1. EXPLORATION AND DEVELOPMENT WELL DESIGN ISSUES The suitability of a subsea well for completion is dependent on its nature as an exploration or development well and more specifically on the way the well was planned. This section highlights various key points which, lf considered early in the well design, can help to make the well more suitable for re-entry and completion should it be required. Seabed Location One of the earliest design decisions for any well is the seabed location. In the case of an exploration well the seabed location re often chosen to be vertically above the target. This is usually no problem, unless other wells have been drilled or are planned close by, in which case future operations may be significantly complicated by overlapping mooring patterns or seabed wellhead obstructions. (Reference 1). As wells become more appraisal rn nature then the seabed location becomes more of an Issue. A decision has to be taken on an optimum location or locations to group wells together In order to avoid the problems mentioned above. If this decision is not taken and wells are drilled individually then the potential savings from being able to reuse existing wells for either a subsea development or a platform development are reduced.

ABSTRACT Since the TROLL FIELD was declared commercial, many different development concepts have been considered based on a fully integrated offshore drilling, production and accommodation platform. Norske Shell has, as development operator and with Partners consent, decided to change this concept to include three main elements. The new concept consists of a less complex offshore platform, pipelines for transport of wet gas to shore, and an onshore processing and compression plant. In the processing plant the gas will first be treated and then compressed for export by pipeline to the European Continent. Land based processing was chosen to improve safety, increase the ability to meet a growing demand for TROLL gas and improve the economic potential of the project. Figure 1. INTRODUCTION A/S Norske Shell discovered hydrocarbons in Block 31/2 west of Beryen in 1979. Figure 2. In the early eighties several appraisal wells were drilled, indicating substantial volumes of gas with some underlying oil, particularly in the West. Neighbouring blocks were also explored and together blocks 31/2,/3,/5 and /6 became known as the Troll Field and was unitised in 1986 and is the largest offshore field in Europe. That same year Norske Shell was appointed Operator for Phase I gas development in Troll East gas province. Figure 3. The ‘troll’ is a creature which often appears in Norwegian folk-lore. The modern troll, however, is located on the Norwegian continental shelf in the North Sea. When gas begins to flow from the Troll field in 1996 it will provide for more than ten percent of Europe's total energy needs far into the 21st century. In fact Troll gas will be exported through several transport systems to a number of countries on the European Continent. The Troll field can be divided into three areas-Troll East gas, Troll West gas and Troll West oil. Oil and gas production from Troll has already started. In 1986 it was decided to export gas from Troll East to the Oseberg field from a subsea production module to enhance oil production from that field. The TOGI (Troll Oseberg Gas Injection) project came on stream in January 1991 and will deliver a total of 25 billion cubic metres of Troll gas for the next 10–12 years. Norsk Hydro is operator for TOGI. In 1989 the Troll Unit Partners decided to test oil production in Troll West. Two horizontal wells have been drilled - the first well was 500 metres and the second was 800 metres long. Both tests indicate that some of the large oil accumulations in the West can be exploited. The oil produced during these tests has generated income to the Partnership and partly covered the cost for testing. Norsk Hydro is also Operator for the oil test project TROLL UNIT PARTNERS The production license for block 31/2 was originally awarded to a group of companies comprising Statoil(SO%), Norske She11(35%), Norske Conoco(5%) and Mobil Exploration Norway(5%). The three adjacent blocks 31/3,/5 and /6 were awarded to Statoi1(85%), Norsk Hydro(9%) and Saga Petroleum(5%).