bluuebunny/crossref_metadata_2025 huggingface dataset:
Benefits of using assisted DP for Deepwater Mooring Systems
Authors: Wichers Johan , van Dijk Radboud
Published: October 2008

For the exploration and production in deeper water use may be made of semi-submersibles and ship shaped types of structures. In the production phase the floaters are normally permanently moored and the mooring system is designed to withstand the local extreme environmental conditions.

Due to the risers and mooring lines in deep water a considerable amount of damping can be induced to counteract partly the low frequency motions. The mooring system however has to take the ultimate forces to keep the vessel on station. In these water depths the length of the mooring lines may be considerable. The cost effect by reducing the mooring system in terms of less mooring lines or a lighter system by applying assisted DP is worth to consider.

As an example a 200 kDWT tanker based FPSO system moored by means of a turret system has been considered. A water depth of 1200 m has been taken. The heavy mooring system may withstand survival conditions e.g. 100-year storm condition.

The same tanker is now provided with a class 3 assisted DP system, consisting of 4 azimuthing thrusters. The size of the passive mooring system (no DP) can be reduced and may withstand a much lower seastate e.g. 1-year storm condition.

It will be shown that the light mooring system including the DP system may be equivalent to withstand the same survival condition e.g. the 100-year storm as the heavy passive mooring system. The results show the effectiveness and benefit in using DP to assist the mooring system in survival conditions.

INTRODUCTION

At present DP assisted tanker based FPSO units are used mostly for heading control. In these designs the location of the turret is located closer to midship than to the bow. Due to the osition close to midship the heading of the FPSO with regard to the environment may become unstable and heading control may be necessary, see Ref.1. For FPSO units with bow turrets permitting weathervaning, the application of DP assistance to reduce the mooring forces is worth to consider.

In deep and ultra deep water not only the costs of the long length of the mooring leg are large, but also the installation costs increase considerably with the water depth.

In applying assisted DP to reduce the mooring forces, the design of the mooring system may be reduced to a passive system to withstand the 1-year or 5-year storm. In higher seastate the DP system must be activated. The average percentage of times of the occurrence of seastates higher than e.g. a 1-year or 5-year storm is relatively small. If a passive mooring system is designed to cope with the 100-year storm, the mooring system will be a heavy one. This heavy system will encounter during the full life cycle a large number of oscillations and different load levels, effecting the strength and fatigue of turret and mooring legs.

In this paper an attempt is carried out to show the benefits of DP assisted turret moored FPSO units in deep water. For deep to ultra deep water computer programs are valuable design tools.
Wave Measurements Using Upward-Looking Sonar for Continental Shelf Applications
Authors: Fiseel David B. , Birch J. Richard , Borg Keath , Melling Humfrey
Published: October 2008

An upward looking sonar instrument the Ice Profiling Sonar (IPS), has been developed, and successfully used for obtaining time series measurements of ice keel depths over the continental shelves of the Arctic in support of scientific research. Since the winter of 1996/97, it has been extensively used off the coast of Sakhalin Island, Russian Federation, in support of offshore oil and gas research aimed at characterizing the seasonal sea-ice regime. The IPS instrument has now been modified to extend its capabilities to provide accurate measurement of ocean waves. The instrument uses a high frequency acoustic transducer (420 kHx). It has a very narrow conical beam (2 degrees width at -3 dB) to minimize the spatial smoothing of surface waves across the sonar footprint. With reduced power consumption, and an expanded internal storage capacity of 64 Mbytes (flash EPROM), the new instrument is capable of continuous measurements of wave amplitude at a sampling rate of 1 Hz over deployments of up to nine months duration. During March to April 1998, an evaluation of the performance of the modified IPS instrument through intercomparison with a wave-rider buoy, was conducted in open ocean conditions off the Pacific west coast. Instantaneous wave heights of up to 11.5 m were measured. The results indicate good agreement between the measurements obtained from the IPS instrument and those measured using the wave-rider buoy. The subsea IPS instrument is very well suited to wave measurement in areas where sea ice or shipping are hazards to surface installations.

Introduction

Measurement of waves at continental shelf depths has been addressed with a variety of ocean instrumentaticns (Stewart1). For some applications, such as where information on the waves encountering an offshore platform are required, rigmounted sensors offer the beat solution. However, often wave data are required before the oil and gas platforms are in an idea, or for the purpose of providing inputs to, or validation of, wave models. For these applications, accelerometers operated within surface buoys are used with data relayed to receivers at shore stations, or via satellite. However, wave buoys are prone to damage from the large waves themselves, from ice if it is present in the area, from vessel traffic or from vandalism. As well, under extreme wave conditions, wave buoys are prone to errors arising from limitations in the response of the accelerometer due to pitch and roil of the buoys (Sky et al.2) and possibly due to the buoys not following the waves themselves under such examines conditions.

An alternate approach is to obtain wave measurements from the comparative safe and calm conditions of the bottom of tie ocean. Bottom-mounted, internally recording instruments, that sample the wave-induced fluctuations of pressure and velocity, are widely used for this purpose.
Deepwater Mooring and Riser Analysis for Depths to 10,000 Feet
Authors: Ward E.G. , Haring R.E. , Devlin P.V.
Published: October 2008

The purpose of this paper is to identify technology needs for analysis tools and methods for designing Floating Production Systems in depths to 10,000 feet. The authors and their colleagues specifically addressed analysis tools and experimental methods needed to establish design values for surface vessel motions and dynamics, riser motions and loads, mooring systems and loads, and the coupled response of the vessel, risers, and moorings for deepwater Floating Production Systems. The identified technology needs were prioritized, and suggested approaches to achieve the desired results are presented.

Introduction

The industry has developed design analyses tools for deepwater Floating Production Systems. These tools were first calibrated and validated with model tests, and in some cases field data and experience from Floating Production Systems installed water depths to 3,000 feet are being used to validate design analyses. As the industry progresses to deeper and deeper depths, these design tools cannot be directly validated or calibrated against data due to limitations in capabilities to conduct directly scaled model tests, and the natural lack of field data or experience in these new depths. The good correlation observed to date provides a strong basis for extrapolating these analysis tools to these new depths. However, data to calibrate or validate these tools in these newdepths, or to identify aspects requiring refinement or further development, are needed. When planning for Phase IV of the DeepStar joint industry project, the Mooring and Riser Committee recognized this need and made it one of the highest priorities for work to be accomplished during 1998–1999.

A workshop process was selected as the most effective means of obtaining input from many experts. Experts representing a broad range of expertise, experience, and perspectives were invited to participate along with Texaco DeepStar JIP members. Some 65 people from 40 companies and institutions participated in the two day workshop, which was held on October 29–30, 1998. Technical presentations and a survey of ongoing relevant research were used to introduce and focus the workshop sessions. Three workshop sessions provided the opportunity for all participants to introduce and discuss technology needs in the areas of FPS motions, FPS risers, and FPS Moorings. Some 70 technology needs were identified and discussed. The technology needs in each area were prioritized, and the final workshop session developed an overall prioritization of the needs identified. This project was conducted by the Offshore Technology Research Center of Texas A&M and the University of Texas on behalf of Texaco's DeepStar Joint Industry Program.
Efficient Integrated Analysis Methods for Deepwater Platforms
Authors: Løken Arne E. , Sødahl Nils , Hagen Øistein
Published: October 2008

Deep Water Floating Production Systems is an integrated dynamic system of risers, moorings and a floater responding in a complex way to loading from wind, waves and currents. The great challenge in selecting the proper strategies for efficient analysis is addressed in terms of analysis techniques and principles of selecting analysis approach. Available analysis methods are discussed with emphasis on treatment of important non-linear effects. A large potential for reduction of the computational efforts involved has been identified based on a careful selection of response model and method of analysis. Efficient analysis will therefore to a large extent depend on the analysts? experience regarding physical system behavior and insight on available analysis methods. A userfriendly computer implementation of advanced as well as simplified methods is hence the basis for cost efficient analysis of Deep Water Production Platforms. Structural reliability analysis is a consistent way of handling uncertainties. This methodology provides a probabilistic basis for decision making under uncertainty with due consideration of cost. Application of methodologies for tension leg platforms, semi-submersibles, deep draft floaters and more conventional ship shaped units are discussed.

Introduction

Efficient Analysis Methods for Dynamics of Floater, Risers and Mooring Systems often constitute the balance between due consideration of different factors affecting reliability and cost of predictions versus the need of the industry. Important questions may be raised such as: How to allocate given resources so that best accuracy is achieved? How to obtain required accuracy by adequate use of resources?

The following efficiency factors for method selection can be summarized as:New designs and design environment for deep water.Design code requirements.Method used can be a function phase of project (i.e. Research and Development, Design and Verification etc.).Physical and statistical model approximation versus confidence to the estimates.Method tailor made for specific object.Tailor made Numerical Solution Methods.Experience feed back from model tests and full-scale information.User-friendly pre-processors and post-processors including graphics.Use of maintained and verified software with cost share and many users. The most important change when working in deep waters up to 2000 meters and beyond is the change in riser and mooring systems, materials, length, weight and increased exposure to fluid forces, see Refs. 1 and 2.
Integrated Mooring & Riser Design: Analysis Methodology
Authors: Connaire Adrian , Kavanagh Kieran , Ahilan R.V. , Goodwin Paul
Published: October 2008

The integrated design of deepwater risers and moorings has the potential to bring substantial benefits in terms of overall system response, cost and safety to a offshore development. Existing design methods, with their origin in shallower water design, have typically not considered design integration. The associated design assumptions need to be reassessed in deeper water, where substantial benetits can accrue from integrated design. The justification for integrated design methods lies in the importance of hydrodynamic loads, stiffness, damping, added mass and potential compliant effects of risers as partof a moored system and also in the need to recognise the precise station keeping requirements of riser systems.

This paper presents the work of a JIP managed by MCS International and Noble Denton Europe and supported by 20 participant operators, contractors, manufacturers and regulators, which has investigated methods of integrated mooring and riser design over 2 1/2 years between 1997 and 1999.

Several altenative innovative riser and mooring analysis methodologies, corresponding to varying levels of design integration, have been developed and investigated for five selected FPS/FPSO systems to evaluate alternative design approaches. The vessels were selected to represent recent state-of-the-art mooring and riser designs in water depths up to 2000m.

Introduction

A comparison of alternative methodologies for the analysis of integrated mooring and riser system designs, representing several different levels of design integration, are described, together with their design assumptions. Their results and relative merits are evafuated against the results of mooring model tests and original design calculations.

Finafly, observations are made on appropriate integrated design methodologies, particularly for deeper waters.

Each of the design methods under review represent increasing levels of complexity and integration of the mooring and riser design. The objective of their evaluation was to investigate the analysis methodology which is robust in representing actual conditions while still being a practical design tool.

The five vessels considered throughout the investigation include a Central North Sea (CNS) FPSO in 150m water depth, a West of Shetland (WOS) FPSO in 400m water depth, a Northern North Sea (NNS) semi-submersible located in 350m water depth, a Brazilian FPSO in 1000m water depth and a generic Gulf of Mexico (GOM) floating production unit (FPU) located in 1700m water depth. The vessels and their associated mooring and riser systems, which are briefly described in Table 1, incorporate a variety of water depths, mooring system types, riser system designs and environmental conditions.
JIP-DEEPER: Deepwater Analysis Tools
Authors: Nestegård Arne , Krokstad Jørgen R.
Published: October 2008

New technical challenges arise when moving to deeper water locations for oil exploration. In order to meet some of these challenges, Det Norske Veritas and Marintek are jointly carrying out a three year research project on Deep Water Analysis Tools - DEEPER under the auspices of the Royal Norwegian Council for Scientific and Industrial Research.

The DEEPER project aims at improving existing procedures for design and verification of deepwater floating production units with emphasis on development of software analysis tools. The most important technical challenges treated in the project are:Strong current loading and viscous forces due to the longer exposed risers and moorings implying that flow induced vibration phenomena may increase.Interaction between mooring/riser dynamics and floater motions requiring coupled solution of mooring dynamics and floater motions. Other aspects covered by the project are improved methods for prediction of low-frequency floater motion, ringing of deepwater tension leg platforms and improved statistical methods for prediction of extreme floater motion and related non-linear responses. The project results will be included in a handbook with practical procedures for use by engineers when analysing deepwater floating structures.

A status and review of methods, corresponding computer tools and analysis procedures developed in the project will be presented. Applications on a deepwater SPAR, TLP and FPSO. will also be included.

Introduction

The Royal Norwegian Council for Scientific and Industrial Research (NFR) has invited Det Norske Veritas (DNV) and Marintek to carry out a Joint Industry Project on "Deep Water Analysis Tools" (DEEPER). The project was started in November 1996 and will terminate December 1999. The total budget is 16 MNOK, of which 40% is financed by NFR. The remaining funding comes from oil companies and engineering companies. The work is carried out by DNV and Marintek. The project also supports three Dr. students, one at University of Oslo and two at Norwegian University of Science and Technology.

The project aims at improving existing procedures for design and verification with emphasis on development of software tools. The need for improved analysis capabilities is emphasised by the fact that depth limitations of existing laboratories make it difficult to carry out model tests with required accuracy for design verification of deep water installations (above 800–1000 m). To enhance and improve existing software tools for use in both the design and verification phase of a deepwater development, is therefore deemed necessary in order to maintain the overall safety and meet the cost reduction challenge of the industry. Supplementary, the so-called hybrid verification techniques, utilising numerical simulations closely linked with model tests can improve the verification reliability even more, see Ref. 1.
Application of Titanium and FRP in Deep Water
Authors: Tørstad Elisabeth H. , Echtermeyer Andreas
Published: October 2008

The offshore industry is moving into new and technically challenging applications due to:The extension of exploration into very deep water.The discovery of high-pressure, high temperature wells.The possibility of wells becoming sour in the long term. Materials with lower weight, better corrosion resistance, and lower stiffness than steel can have considerable advantages for these new applications. Titanium and fiber reinforced plastics are materials that can meet these challenges and interest in the two materials has increased considerably over the last years.

The most prominent application at the moment is risers, because of the great advantage of weight reduction. One titanium riser has already been installed in 1995 and further applications are considered in the North Sea. Composite risers have been tested extensively in various research programs and the first prototypes should be installed very soon. DNV has been deeply involved in the qualification programs and selection of the materials for these risers.

Extensive test experience and theoretical knowledge of titanium exists today. Test-programs have included mechanical and fracture mechanical testing as well as fatigue testing and corrosion testing. Both base materials and weldments (TIG and EB) have been tested in realistic environments at elevated temperatures. The materials microstructural features have also been documented and compared to other properties.

Composite materials are also well understood, but the documentation of especially long-term performance has only been achieved recently in some cases. An FRP design guideline is currently being developed in a JIP. This work should provide a widely accepted basis for the safe use of FRP in many applications.

It is believed that exploration of deep-water fields with more aggressive and sour well fluids keeping high temperature and pressure will further emphasize the need for materials with outstanding properties.

Introduction

DNV has worked with the materials in question in a number of projects.

The main interest in titanium for deep water applications was initiated when Conoco considered it a possibility for the drilling riser on the Heidrun field. DNV performed a series of qualification projects in the years 1992 – 1994 concerning fatigue life and fracture toughness of titanium Grade 23. Finally, titanium was chosen for the entire Heidrun drilling riser except for the top section. The riser is rated to 300 bar, and the gas and oil extracted are expected to become sour in the long term.

Figure 1.-The Heidrun platform (Available in full paper)
Spacer Design and Fabrication for Sakhalin II Project
Authors: Bruce J.C. , McCaslin B.T. , Hollowell J.A.
Published: October 2008

Sakhalin Energy Investment Company has refurbished and redeployed the Molikpaq, an arctic offshore drilling caisson originally designed for use in the Canadian Beaufort Sea. The original structure has been deepened by adding a new pontoon base, named the "Spacer", and converted into a drilling and production unit. It is now placed 16 km off the coast of Sakhalin Island as the first production unit in the Russian subarctic. This paper describes the design of the 15,000 tonne Spacer unit, its fabrication in Russia and the mating of the Spacer to the 35,000 tonne modified Molikpaq structure at a Korean shipyard. The paper also describes the interrelationships among the participants involved in this fast track project; the challenges of designing for a new frontier area with severe wave, seismic and ice loadings; and the challenges for the Russians and the Owners of building a new type of structure in a yard designed for building submarines.

Project Overview

The Piltun-Astokhskoye (PA) Field, located in the Russian Far East in the Sea of Okhotsk, was discovered by Sakhalinmorneftegas (SMNG) in 1985. Subsequently, SMNG drilled 13 additional parametric wells on the structure. Members of the consortium now called Sakhalin Energy Investment Company Ltd. (Sakhalin Energy) were awarded the rights to further explore the PA Field in March 1992.

In 1995, the Upstream Operator, Marathon Upstream Sakhalin Services Ltd., with the aid of several engineering contractors, evaluated the use of the "Molikpaq" (or platform PA-A) as a way to bring early production to the PA Field. The Molikpaq, a massive, octagonal, Mobile Arctic Drilling caisson, was constructed in the early 1980s for Gulf Canada Resources Inc. and used as a drilling platform at several locations in the Canadian Beaufort Sea (ref: 1, 2). Although the Molikpaq was constructed specifically as a mobile offshore drilling unit, the engineering studies indicated that it could be modified to support additional wells and process facilities and become a full production platform operating safely in the challenging wave, ice, and seismic conditions characteristic of the Sakhalin region.

Figure 1: Modified Molikpaq Platform at the PA Field (Available in full paper)

The Sea of Okhotsk presents enormous challenges for offshore production. Ice-covered for half the year, it generates severe waves during the open-water season and is one of the world's most seismically active regions. The challenge was to develop a platform that could accommodate the environmental forces and yet be brought on stream on a fast track basis.

To accommodate the 30 m water depths and harsh wave climate, the Molikpaq had to be deepened. After assessing a number of alternatives, the solution chosen was to design a pontoon-type steel base, ultimately named the "Spacer", which added 15 m to the platform depth.
Britannia Export Pipelines: Pushing The Boundaries
Authors: Baker Dave
Published: October 2008

This paper will outline the significant design improvements and cost savings made possible by a successful alliance of owner, pipeline designer and pipelay contractor on a major export pipeline development in the UK Sector of the North Sea. It will describe the areas where the majority of the cost savings were made and how the internal workings of the alliance, within an integrated team environment, used their combined resources to achieve a superior result. Technology advances discussed include Limit State Design methodologies, the use of high strength linepipe steel, non-standard pipeline size, simplified crossing design and trenching versus wall thickness versus concrete weight coating.

Introduction

In December 1994 the British government granted approval of the Britannia Development Plan following the formation earlier that year of a new company, Britannia Operator Limited (BOL), established between Conoco and Chevron.

The creation of BOL, a limited company with no employees and shareholdings and accounts available for public scrutiny, was seen as the best way to form an operating entity that will look and function as a single operator company. This approach brings clear accountability and decision making within an integrated management structure that simplifies the agreement reaching process between Chevron and Conoco which, between them, hold nearly 73% shareholding in the field.

This unique partnership between two operators and the philosophy developed by the original management team in April 1993, has been continued throughout the project by the formation of a number of alliance based contracts, as well as the more traditional form of reimbursable/lump sum contract.

One such alliance contract is that responsible for the export pipelines scope of work and it is this element of the Britannia Project that is the principal focus of this paper.

The Britannia Export Pipelines

The Britannia Field is a gas condensate reservoir located 130miles (210km) north east of Aberdeen in Scotland in 450feet (135m) of water and some 30miles (45km) north of BP's Forties Field. Dry, dewpoint controlled gas is exported in dense phase mode through a 27-inch nominal diameter trunkline, 116 miles (186kms) long to an extension of the Mobil SAGE Terminal at St. Fergus. At the terminal the gas is processed for delivery into the British Gas National Transmission System. The condensate is transported through a 14-inch interfield pipeline 27 miles (44kms) long to the BP Forties Unity Platform. (The pipeline schematic is shown in Figure 1 with the Pipeline Parameters summarised in Table 1).

Table 1 Pipeline Parameters (Available in full paper)
Managing Patent Quality: Examples/Advice for Offshore/Marine Technology
Authors: Groover Robert
Published: October 2008

With patents, as with blowout preventers, failure in the field is an expensive way to obtain the necessary feedback for quality control. However, where quality and reliability issues are concerned, engineering and corporate managers typically understand better how to communicate with engineers that with lawyers. This talk presents some tools for managers to communicate with their patent lawyers regarding patent quality.

A valuable invention does not necessarily lead to a valuable patent: a patent which is known to be invalid, or which will never be infringed, is worthless. The value of any number of patents does not indicate the value of your portfolio. However, correction for invalidity and noninfringement is not easy, because these are legal conclusions on which good lawyers can argue both ways. This talk presents a more usable analysis, based on forecasting costs and risks.

Introduction

All patents are not created equal. Any experienced patent attorney has had the sad experience of reviewing a patent which was filed on the right invention on the right time, but which can't be asserted against the people who are now using that invention. Such experiences are often very damaging to the company, but are hard to learn from: the relevant mistakes are typically far in the past by the time the loss is discovered.

Optimal management of patent activity can be critical to preserving a company's strategic position. However, the trade-off between the short-term constraints of finite cash flows and the long-term strategic goals of the company is difficult to manage. This talk will attempt to provide some theoretical foundations which will help non-attorney managers to optimize their patent programs. In particular, this talk addresses the difficult problems of managing patent quality. (Of course this talk presents only general points, and does not state or imply any advice as to anyone's particular situation.)

Distinctive aspects of patents, as a management problem, include: long time horizons; rapidly changing legal climate; and returns which are very heavily concentrated on a small percentage of patents. This article presents an approach to patent management, and particularly to patent quality management, within the conceptual framework of risk management - both offensive and defensive. Specifically, this article uses a "gray-scale" analysis of vulnerability to argument, which can be useful in communicating with your lawyers. Note that the long time scales and highly skewed distribution of patent value mean that patent quality management must be treated as an "open-loop" problem. With patent management, as with disaster management, learning from one's own mistakes is too slow and too expensive a learning process.

This paper will first review some of the ways patents can impact your business, some basics of the patenting process, and some features of the distribution of returns on patenting; all of these preliminaries will serve to provide context and motivation for the quality guidelines which follow.
The Disposal of Oil Produced During Offshore Well Tests on Wildcats Without Facilities
Authors: Glotin Bernard
Published: October 2008

1. Abstract

Weather conditions, difficulties in programming tests and problems of storage security on the drilling barge often make it impossible to carry out offshore well tests if there are no means of disposing of the oil.

FLOPETROL has made a study of the destruction of the oil produced during initial tests by means of specially designed burners.

Particular characteristics of this oil are the unsteady rate of production and heavy pollution by water, mud and solid particles (sand and Capsule gun debris).

The burning device produced as a result of FLOPETROL's research enables the polluted oil to be burned and is designed in such a way that the platform is completely protected from the heat given out on combustion.

2. Introduction

Well tests both on and offshore are carried out on more or less the same principle. Offshore, however, tests should be completed as quickly as possible for the obvious reasons of cost.

At the present time there is no particular difficulty in carrying out tests on wells producing dry gas, even on a drilling platform. In the North Sea it is common to obtain gas flow rates of 30 MMSCFD and, for security reasons, to burn off the gas without any ill effects on the equipment.

The case of oil wells or wells producing an effluent rich in condensate is not the same and disposing of the effluent creates a real problem.

For drill stem tests of short duration it is possible to stock the small quantities of effluent produced on the platform and afterwards to arrange for the transport of the full tanks to land by a supply boat.

If the tests are to last for some length of time and the flow rate is high, it is not possible to stock the oil on the platform due to lack of space, maximum loading restrictions and for reasons of safety.

Various solutions can be considered to solve this problem but none is particularly satisfactory.

One solution is to transport the oil to land by means of a tanker. The boat must be positioned near the well and loaded by gravity, the oil having first been passed through a low pressure separator. A flexible hose is required and the boat must have an excellent anchoring system.

This method is often employed for large quantities of oil, in the Middle East for example. But the system is not sufficiently adaptable - a boat of the required capacity must be chartered in time and there is always the possibility of the boat's arrival being delayed by bad weather. It is also necessary to be in an area where there are adequate unloading facilities on land and that there should be no customs or administrative problems. These difficulties often render this operation very costly.

Another solution is simply to dispose of the oil directly into the sea. All countries forbid this practise but, for very small quantities several companies resort to this method in cases of absolute necessity. This procedure can be dangerous.
Morpeth Export System
Authors: Kennefick Jonathan , Lang Peter , Hervey Donald
Published: October 2008

British-Borneo Exploration Inc.'s Morpeth export system introduces two industry firsts -- the use of a diverless piggableb tie-in sled installed in a stacked orientation through a stinger and the installation of the first dynamic steel catenary riser (SCR) employing Slay techniques. Careful design and installation planning resulted in successful on-bottom positioning of the sleds within 5° of vertical without any rectification. The pipeline and SCR Slay work was performed from a conventional, moored barge in water depths ranging from 360 to 1650 feet along the 19.5-mile route.

Introduction

The Morpeth field is located in Ewing Banks Block 965. The field layout is illustrated in Figure 1. Oil and gas from the field are produced from three subsea wells in 1750 feet of water via flexible catenary risers to the Atlantia-designed SeaStar® mini-TLP located in EW 921 in 1650 feet of water. Product is then exported through a 12" and 8" gas steel catenary riser and pipeline system to a conventional platform in GI 115 in 360 feet of water. The subsea facilities are operated remotely from the TLP.

The installation of the export system was performed with J. Ray McDermott's combination lay/crane barge DB28 in two phases to maintain the 21-month fast-track schedule. The bulk of the pipeline was laid in the first phase in the Slay configuration, terminating at the piggable tie-in sled location. The sled, the remaining 2 miles of each pipeline, and the SCRs were laid in the second phase in the S-lay and the J-lay configurations, completing the export system installation.

Figure 1 Morpeth Field Layout (Available in full paper)
Cantarell Oilfield Optimization and Surface Infrastructure Enhancement.
Authors: Aguilar A. Aguirre , Crookshanks M.
Published: October 2008

PEMEX owns the Cantarell Offshore Oilfield, one of the biggest oil reservoirs in the world. It's located in Campeche Bay, in the Gulf of Mexico.

The purpose of this paper is to explain the optimization and surface infrastructure enhancement program, tht is one of the programs involve in the project This program includes using the EPC model and worldwide known engineering, certification and construction companies are participating to increase the reliability of the facilities, in order to obtain a world class quality.

The optimization and surface infrastructure enhancement program, includes the elimination of the existing bottle necks (Debotlle-necking). As well it, includes the expansion and modernization of the actual infrastructure, decreasing the gas flare and obtaining the maximum, flexibility and reliability increasing the capability of oil and gas management.

These works involve a great deal of efforts including very large scope jobs on the oil facilities complex currently in operation. At the same time includes a nitrogen plant facility which will produce 1,200 million cubic feet of gas per day. Also included is 23 new platforms; nine drilling platforms (eight octapodes and one tetrapode), two oil production platforms, four compression platforms, one process platform, six offshore living platforms and the construction of fifty five pipelines, that means a total of 357 kilometers of lines. And finally, the construction of an offshore floating storage and offloading system (FSO).

Introduction

The Cantarell offshore oilfield is the more important in México as for the volume of reservoir because is considerated the sixth in worldwide position as its aportation to National production. It's located to 80 kilometers from shoreline of Campeche State and has a extension of 161 square kilometers. The Cantarell oilfield is integrated by several oilfields named AKAL, NOHOCH, CHAC and KUTZ or bloks limited by a faults which to make an anticline with NW-SE orientation. It's located between depth water from 33 meters in the south to 55 meters in the north of the oilfield, the marine soil is composed by soft lime clay and high soft lime clay.

The quality of the Cantarell's crude oil is from 19° to 22° API.

The Cantarell oilfield has been working from the 1979 year and currently has three complex in operation, 38 peripheral platforms and 1960 kilometers of pipelines, with a total production of 1,400 MBD in crude oil and 760 MMCFSD in gas.

The Cantarell Project is the biggest ambitious project stablished by PEMEX, the above made to development previous studies or analysis to assure the feasibility of the proyect.
Nigeria Deepwater Geophysics for Exploration and Development
Authors: Ghosh Deva
Published: October 2008

SNEPCO on behalf of a consortium including ELF, AGIP, ESSO acquired a large 3D survey of 3500 sq.km in water depths ranging up to 1500m, in OPL 212 and 219 in deep offshore Nigeria. The early application of state of the art 3D technology has given SNEPCO and its partners sufficient lead-time to drill the first discovery well in less than two years in this frontier.

Geophysical Issues.

Innovative ideas have been implemented in acquisition and processing yielding high technical standards in a cost effective manner without jeopardizing either quality or turnaround. This includes 3D DMO for imaging and infilling, wavefield reconstruction for multiple elimination and constrained phase/true amplitude preservation.

Long 6km cable in AvO played a strong role not only in hydrocarbon porefill prediction but also in ranking and classifying leads and prospects. The 3D prestack migrated data allowed for accurate AvO prediction & resulted in the discovery well, Bonga. This was further followed up by static and dynamic modeling and inversion studies.

Appraisal & Development.

Geophysics has played a very strong role in the appraisal campaign, which included the drilling of three wells in the Bonga field. Our finds were in line with prediction from AvO/Inversion studies made in terms of depths, thickness of reservoir and fluid content. 4D seismic is planned for fluid monitoring.

SNEPCO is making an extensive campaign exploring and developing acreages offshore Nigeria by utilizing its worldwide experience.

Introduction

Sedimentary basins in deep waters from 500m to 2000m and beyond are currently the subject of intensive exploration for hydrocarbon potential as evidenced by big finds along the West Coast of Africa.

SNEPCO on behalf of a consortium including ELF, AGIP, ESSO acquired a large 3D survey of 3500 sq.km in water depths ranging up to 1500m, in OPL 212 and 219 in deep offshore Nigeria. The early application of state of the art 3D technology has played a major role in enhancing SNEPCO and partners' position in this frontier area giving sufficient lead time to drill the first well in less than two years.

The new acreage provided a challenge to Geophysicists in acquiring/processing and evaluating seismic data in a relative short time frame. Innovative ideas have been implemented in acquisition and processing yielding high technical standards in a cost-effective manner without jeopardizing either quality or turnaround.
Quad 204 - Using Competitive Advantage to Deliver Value
Authors: McHugh Pat
Published: October 2008

This paper presents a general description of the UK Atlantic Margin and an overview of the first two developments in the area, BP Amoco's Foinaven and Schiehallion fields.

BP Amoco operates the Foinaven Development on behalf of BP Amoco and Shell Exploration & Production, and operates the Schiehallion Development on behalf of BP Amoco, Shell Exploration & Production, Amerada Hess, Statoil, OMV and Murphy.

It discusses the knowledge and insights we have gained from the experience of bringing these two fields into production and assesses the real value of the innovation in the application of technology and new relationships within the industry which has been central to both Foinaven and Schiehallion. It also introduces the papers which follow in this section:

Development Drilling Innovations for the Foinaven and Schiehallion fields, in the UK Atlantic Margin

Walder DR, Mountford CF, Howes D, Parr RS

Lessons Learned from the Schiehallion FPSO's Design and Construction

Green J.M.

Successful Delivery of Deep water Subsea Developments in the UK Atlantic Margin

Smith T, Pettigrew G, Worsley M, Walls B, Clark E, Brookes D

Deep water FPSO and Subsea Facilities - installation, hook-up and commissioning in Schiehallion, on the UK Atlantic Margin

Dick M (SSOL), Sen P (Fuel), Metcalf P (KOG)

Operating on the Frontier - over two years of FPSO operating experience in the harsh UK Atlantic Margin region

Krafft H (Golar Nor), Thomson L (BP)

Three years ago, BP Amoco presented a similar series of papers to the Offshore Technology Conference, describing the status of our Atlantic Margin activities - progress with the Foinaven project, our plans for Schiehallion, our hopes for further activity and developments in the area and above all how we saw the technological, commercial and environmental challenges which lay ahead.

Three years on, we now have two successful operations in the Atlantic Margin with 18 months experience of production from the Foinaven field and 10 months of Schiehallion production. We are achieving stable production of 85,000 bpd from Foinaven which came on stream in November 1997 and over 100,000 bpd from Schiehallion which began producing last July.

Both fields use similar floating production systems - moored FPSOs equipped with internal turrets and swivel stacks as the most cost effective way of exploiting the relatively shallow reservoirs.
High-power Subsea Electrical Connector Technology: Meeting the Challenge
Authors: Musker F.
Published: October 2008

Subsea electrical connectors are now common place for low voltage data communications with subsea control modules, sensors and actuators. This patented and proven technology, based on pressure balancing techniques, is now being applied to higher power applications, feeding electrical power to a variety of pumps. separators and pipe line heating systems. This paper details the advances in materials, connector design, testing and analysis which have been addressed to support voltages to 36,000V and current up to 1000A.

Applications for this technology first arose in 1987 when an 11,000V connector was developed for the SBS project for AGIP, followed by the SISL project (OTC paper 7289, 1993 by J.A. Nicholson1), which was the basis of the well head connector design for Petrobras RJS 221, the world's first subsea ESP project.

Since then, Amoco Liuhua - the first commercial ESP project, has provided reliability data for medium power connector systems across 20 wells, and many other projects are emerging. This paper outlines the various applications (past, present and future) and addresses the challenges now being faced by the connector manufacturer.

The demand for more power and smaller space envelopes has driven materials development to produce polymers which have high dielectric strength combined with tolerance of high temperatures and good mechanical stability. The paper will include an overview of material advances and will detail the significant impact which these new materials have made on the overall performance of power connectors. The subtle differences between varied applications are also described, including advanced termination practices.

The high power electrical connector represents key enabling technology and is of strategic importance to the industry as a whole as higher power pumps, complete multi element subsea distribution systems and separators proliferate.

Introduction

The development of subsea power connectors has been a continuously ongoing process for more than 10 years. The early designs concentrated on dry mateable subsea deployed connectors.

To appreciate the next steps we need to review the history of the development by a potted history of the progress attained to date.

From Tronic's viewpoint a major technological step towards wet mateable subsea connectors came with the successful qualification testing of the Controlled Environment (CE) principle.

The initial development of a 6.6kV single pin wet mateable connector (funded by AGIP) began in 1989, the project was successfully completed and fully tested in 1991. This successful completion led to the extension of the project to include an 11kV 400A 3 pin subsea mateable connector, this development was completed in 1992 after a stringent and successful test regime.

In 1991 the development of a wellhead power connector for ESP application was initiated by Subsea Intervention Systems Ltd, a joint venture between a number of oil companies and manufacturers.
Turret Mooring System: The Key to Oil Production in the Extreme Atlantic Frontier Environment
Authors: Vogt Christoph , Goodman Martin L. , Han Commandeur J.A.
Published: October 2008

This paper describes the engineering solutions for the mooring and fluid transfer system meeting the challenges for the Schiehallion FPSO installed West of the Shetlands Islands in the UK sector for BP Exploration. It will also highlight some of the related aspects met during the construction and installation of the system.

This FPSO was installed in summer 98 and started producing oil on the 29 July 1998, 27 months after project sanction. It will remain on station in this harsh environment for 25 years, weathervaning around a turret anchored to the seabed by means of an array of 14 composite anchor legs. The turret mooring system belongs to the family of the "passive free weathervaning internal turrets" and allows the installation of up to 24 risers for oil production, gas lift, water injection and well control.

The turret incorporates two novel design features including:–The main weathervaning system of the "passive internal turret" consisting of a sophisticated bogie arrangement instead of the more conventional single roller bearing solution.For the combined requirements for strength (extremely large mooring loads), space (multiple risers) and redundancy, the bogie solution, derived from crane technologies have now been applied.–The swivel-stack, which is inverted and is suspended from the gantry structure, so reducing the overall height of the turret manifold and gantry structure.The FPSO is now at its location for approximately 4 months. The turret mooring system has proven to be the ideal solution for applications in extreme environmental conditions, for large field developments and high production rates.

Introduction

A contract was signed in June 1995 between BP and an Alliance comprising B&R, Harland and Wolff and SBM to develop the FPSO for Schiehallion. Sanction was given to the project by BP and his partners in February 1996.

The harsh environment encountered in the Schiehallion field, offshore the Shetland Islands in the Atlantic Frontier area, in combination with the 24 risers, required a new dimension of a mooring system. An Internal Turret was chosen to allow the vessel to freely weathervane and to transfer the fluids and services from subsea to the vessel and reverse. The required turret diameter to accommodate 24 risers precluded the use of a conventional slewing ring arrangement as used in the previously built SBM turrets for the North Sea. Two designs were studied and compared, a split rollerbearing of 12m diameter, mounted at the vessel maindeck level and a bogey arrangement derived from previously used systems in the large Offshore cranes delivered by IHC' Gusto yard. The bogey system was chosen for the application, design features and some of the challenges for the construction are described in the following chapters.