ABSTRACTS FROM

THE PROCEEDINGS OF

THE 12^TH OFFSHORE SYMPOSIUM

International Offshore Development

Success and Challenges

Houston, Texas – February 19, 2003

Opening Session

International Offshore Projects – The Challenge of the Legal Road

Scott C. McClure and Lars Ronning, Alan C. McClure Associates, Inc.

An Engineer, an Accountant and a Lawyer walk into a bar...

But seriously folks, expert witness work is no joke. International offshore development projects are challenging both technically and contractually sometimes leading to disputes. Every year millions of dollars are spent by companies taking their dispute through the legal system. While lawyers are the experts on how the legal system works, they often require outside expertise to help them understand how industries, such as the marine industry, work. Sources of such expertise include engineers and forensic accountants. The engineering effort to reconstruct an accident or a time table of events may be extensive. This effort must be carried out under strict fidelity to an open mind to provide an unprejudiced result. In most cases this culminates in an expert opinion which may eventually be used in a court of law.

Coordinating Vendors Internationally

Jason Petten, American Bureau of Shipping

The offshore industry is moving into deeper water. New technology is continually being introduced. Regulatory requirements are ever evolving, and the marketplace is becoming more international and interdependent. This all makes offshore projects increasingly complex and requires the use of more vendors and sub-vendors from around the world. This paper discusses some workable solutions to common challenges faced by vendors and clients when working on offshore projects.

Session A: Student Activity and Contribution

ISODC - The First Year. Lessons Learned

Andrew Breuer, American Bureau of Shipping, John Filson, FSEA

The International Student Offshore Design Competition (ISODC), is a team-based design competition for undergraduate students in various engineering disciplines applicable to the offshore industry. Its main purpose is to develop a heightened awareness in the academic world of the professional opportunities in the offshore industry and likewise to develop in the industry awareness of capable talent. It was originally developed under SNAME sponsorship and was later joined by the OOAE Div of ASME and has most recently been joined by the COPRI Div of ASCE. The paper will give an overview of ISODC and the events of it first competition, “ISODC2002.” In addition the mission and goals of ISODC are given along with an outline of it functional structure. Finally, a key element of ISODC, its mentorship program will be examined.

Oil Rig Classification in Mexican Offshore Industry

Mariano Azzur Hérnandez Contreras and Gustavo Francisco Barreto Sosa, Universidad Veracruzana

In major coastal waters of the world it is a legal requirement that offshore installations hold a valid Certificate of Fitness. The intention of this legislation is to increase the safety of these high-risk installations through an independent check of the design documents and through surveillance during construction and operation. This task is performed by relevant national authorities.

Although it is the ideal case that the Certifying Authority (CA) follows a project from the very beginning, so that he/she can influence in the design with regard to safety, it is also possible, and has already been performed successfully, to certify existing installations. For existing platforms their age and the environmental conditions they have been exposed are to be taken into account. This document shall give a brief outline of the requirements and the procedure for certifying existing offshore installations in Mexico.

Environmental Damages Caused by Oil Spills in the Gulf of Mexico (Causes and Solutions)

Oscar Manuel Gómez Díaz, Universidad Veracruzana

As it is known, the power sector, especially the one of hydrocarbons, has been a fundamental platform for the economic growth of our country. Mexico not only counts on abundant reserves of crude petroleum and gas, also it has developed an oil industry of great complexity and value.

Nevertheless these developments have brought with them the development of new security and environmental protection plans due to the necessity to maintain intact the natural resources of our country .

This presentation has by primary objective to show some technical aspects about oil spills, zones of risk and what actions to take for prevention and fight of this type of environmental contingencies in individual of the Gulf of Mexico.

The program of this presentation includes the following topics:

· Oil spills classification in Mexican offshore industry,

· Causes (oil spill forms and aspects),

· Zones of high risk in the Gulf of Mexico,

· National environmental contingencies plan of Mexico,

· Conclusions.

Session B: Risers and Station Keeping

Latest Developments of Azimuthing Thruster System in the Offshore Market

Roland Schwandt, Jack Chancellor, Schottel

This paper describes the development of thruster systems in the offshore market from fixed installed azimuthing thrusters over retractable thrusters to underwater demountable thrusters. Advantages and disadvantages of the different thruster systems will be shown related to their operational use and be pointed out with specific examples of the offshore market. Aside from the existing thruster systems alternative systems will be shown and their strength and weakness in comparison to the existing once will be pointed out.

Tendon and Riser System Enhancements - The Key to Ultradeepwater

Henrik Hannus, Aker Kvaerner Inc.

TLPs are established as a viable concept for water depths up to about 4000ft. Beyond that, the weight of traditional tendons and risers impose an increase in the hull size, reducing the relative competitiveness. This paper describes alternative tendon systems (composite and stepped diameter) and composite riser systems, their technical status and economical benefit.

Construction Stretch in Polyester Mooring Lines: What Mooring Designers Need to Know

Barbara A. Stone, Sea Engineering Inc., Mark Huntley, Whitehill Manufacturing

Polyester mooring systems are under consideration for an increasing number of deep water developments. While there is an increased knowledge in the mooring design community about the behavior of polyester mooring lines under various environmental loads, there is still a great deal to learn about installation issues. Of particular interest is the behavior of the rope under initial loading conditions during installation.

Results from a simple testing plan on polyester mooring ropes show the effect of various loading levels on removing construction stretch in the polyester rope. Based on these results, a number of installation scenarios can be developed that effectively remove the construction stretch in the polyester rope while minimizing potentially problematic installation issues.

Session C: FPSO

The Latest Trend in Steam Boiler Design and Conversions for the Offshore and FPSO Applications

Hans Matti, Holger Nilesen, Aalborg Industries

Aalborg Industries is one of the leading suppliers of boilers for marine vessels, but also for FPSOs and FSOs. The wide range of products and a strong after sales organisation gives a good platform to work from. Some boilers have been installed in safe area engine rooms, but most of them have been installed on open deck in hazardous areas.

The paper discuss various interesting issues like steam, hotwater or thermal oil as heating media, gas or steam turbine for power production, new boiler or conversion of existing boilers, and whether the boilers should be installed in the engine room or on deck. The paper also gives some interesting case stories.

A Model of the Flow around Bilge Keels of FPSO Hull Sections Subject to Roll Motions

S.A. Kinnas, H. Lee, Y.-H. Yu, and B. Kacham, University of Texas, Austin

FPSO hulls have often been found to be subject to excessive roll motions, with amplitudes larger than anticipated or predicted.

A computational model is being developed at the University of Texas at Austin for the study of the 2-D flow around an FPSO hull section with and without bilge keels. The model is based on a finite volume method (second order in terms of space and time) to solve the unsteady Euler or the Navier-Stokes equations. The linearized kinematic and dynamic boundary conditions are applied on the free-surface.

The method is first being tested in the case of alternating flow past a vertical plate. The predicted inertia and drag coefficients on the plate from the numerical solution of the Euler or the Navier-Stokes equations, are compared with each other and with the measurements from a known experiment, over a range of Keulegan-Carpenter numbers. It is shown that the computed and measured forces are in good agreement with each other.

Finally, the method is being applied in the case of a 2-D FPSO hull section (bare or with variable size bilge keels) subject to forced roll motions, and the corresponding added mass and damping coefficients are compared with those from other methods as well as those reported from known experiments, over a range of Froude numbers. The application of the method on actual FPSO hulls and its potential to understand, and subsequently improve, the effectiveness of bilge keels as roll suppression devices will be discussed.

A Comparison of measured and calculated vessel headings of a turret-moored FPSO

Jeroen van der Cammen, Martijn Hoogeland, Bluewater Energy Services B.V., Jos de Koning, Maritime Research Institute Netherlands (MARIN)

In this paper a comparison is made between measured and calculated vessel headings for a period of more than 3.5 months. The calculation procedure consists of determining the average, stable equilibrium heading in a non-collinear environment by determining the stable angle of the zero yaw moment around the turret from wind, sea waves, swell and current. The full-scale measurement data used in this study is measured onboard Bluewater’s FPSO “Bleo Holm”, located at the Ross & Parry field at the North-Sea UKCS and consists of a continuous log of vessel heading, wind speed and direction and vessel draft and trim. Wave, swell and current data are also necessary as input for the calculations and are obtained through hindcasting. Vessel heading calculations are made for the case when using wind data measured onboard and for the case when using wind data from the hindcast database. A comparison between measurements and calculations is made and it is determined where the calculations match the measurements and where the calculations fall short of them.

Application: Calculation of the vessel heading is the first step in determining the responses of a turret-moored vessel in non-collinear environments. The second step is the calculation of the vessel responses in each sea-state given the vessel heading relative to wind waves and swell. This calculation method is used for the long-term assessment of roll motions and hull fatigue of a weather vaning FPSO.

Results, Observations, and Conclusions: It was found that the calculations matched the measurements reasonably well. When the wind data measured onboard were used as input the calculations matched the measurements better than when hindcasted wind data was used. It was found that the two main reasons for differences between measurements and calculations were changing weather conditions and the accuracy of the hindcast data.

Significance of Subject Matter: The calculation technique to determine vessel headings of turret moored vessels in non-collinear environments is straightforward and simple, but has, as far as the authors know, never been tested against actual measurement data from an FPSO. The algorithm is quick so it can deal with large quantities of data, but the procedure must also have enough accuracy. This paper gives a comparison between full-scale measurements from an FPSO in production against the calculation method and shows how the calculation procedure performs.

Session D: Floating Facilities

Advanced TLP Designs – Strategies for Deepwater Development

Pieter Wybro, Sea Engineering Inc., Ray Koon, MODEC

Recent advances in TLP technology enable TLP systems to be technically viable for development of hydrocarbons in water depths to 7500 ft and beyond. These technology advances consist of: efficient and lightweight topsides; new generation efficient hull and deck designs with superior hydrodynamic performance; accurate numerical prediction of TLP performance; effective strategies for mooring and riser systems design; and novel platform installation methods. The relevant design issues for deepwater TLPs will be discussed, and features of the enabling technologies will be discussed with extensions to water depths of 7500 ft. using existing technology. It will be shown that the performance prediction of the deepwater TLP is well understood, by comparison of numerical predictions to model tests.

TLP designs for mild environments such as West Africa and Brazil can achieve greater efficiencies which will also be discussed.

Design, Analysis and Operation of the ENSCO I Barge on Barge*

Gene Facey, Paul Wildberger, ENSCO International, Inc., Bui Dao, Jim Ochs, Ocean Design Associates, Inc.

In this paper, the design and analysis considerations for the ENSCO I Barge on Barge (BoB) drilling unit are outlined. The BoB is comprised of the ENSCO I drilling barge with a new-build mat (support barge) added on its bottom. The ENSCO I BoB will operate offshore Balikpapan, Indonesia in a very challenging environment described by shallow water with large tidal variation.

The ENSCO I is an existing ABS Classed drilling barge initially designed for use in Lake Maracaibo. In its present configuration, the unit does not have especially shallow draft transit nor adequate deck height to accommodate the highly varying tide. A solution was to design and fabricate a mat to put underneath the drilling barge. The mat is currently under construction at Keppel FELS in Singapore.

The BoB is intended to transit in the afloat mode on the new mat. A significant ocean voyage from Singapore to Balikpapan will be followed by short duration field moves. Drilling operations are conducted with the BoB sitting on the sea bottom. Due to the high tidal variations, a tank-tidal system was designed to avoid excess buoyancy during high tide as well as excess on-bottom weight during low tides.

The design and analysis considerations relating to mat sizing, mat design, global strength in the transit mode and on-bottom mat strength while drilling are outlined in detail. We will also discuss the mechanical systems provided in the mat as well as modifications to the systems of the ENSCO I.

The Marginal Field Deep Draft Semi - A New Application of Proven Technology

H.Hannus, N. Haug, S.Zuhn, Aker Kvaerner Inc.

A deep draft semisubmersible platform will be presented. The concept has been developed for Gulf of Mexico marginal field developments, based on subsea wells and Steel Catenary Risers. The design is driven by the performance required by the SCR's, while maintaining conventional and proven building blocks for the moorings, the pontoons, the columns and the deck. A major driver has also been to complete all integration of the platform quayside, thereby avoiding the cost and risks associated with offshore lifting. Model test results will be presented that confirm the excellent motion characteristics.

Closing Session

Human Factors Engineering and Cultural Calibration for an Offshore Platform Design

Denise B. McCafferty, American Bureau of Shipping, E. Johan Hendrikse, Paragon Engineering Services

“For technology to travel well, it should be culturally calibrated.” This paper will discuss some of the lessons learned during the application of human factors engineering (HFE) onto new offshore installation designs.

Installation production availability is critical and is largely dependent upon the reliability and maintainability of equipment, which in turn is influenced by human operational and maintenance activities. It is for this reason that it is important to incorporate HFE as a part of the design basis.

In order to obtain the best benefit from HFE, it is necessary to look at the unique characteristics of the expected user population for the facility. This would ensure that the design reflected the expected physical, psychological and cultural attributes of the user population.

This paper will highlight the methods and data used to derive criteria as well as the HFE program management methodology. From an HFE technical standpoint, the challenges associated with labeling and signposting with multi-lingual crews will be discussed. The approach used to address traditional HFE concerns including anthropometrics, manual materials handling, access/egress, control panel design, personal protective equipment, etc. will be presented in the paper. The intended result is to provide a road map for maritime design efforts where project teams are designing for user populations in other countries.

Floating Offshore Facilities for the Power Generation Industry

David Waller, Tony Martinez, Waller Marine, Inc.

Stranded offshore gas in remote areas of the world provides opportunities to develop new fuels for electrical power generation plants in developed countries. New gas to liquids technologies (GTL) are becoming available that permit the production of liquid fuels and their transportation to market at prices competitive with traditional technologies, such as LNG. GTL technologies that can produce large quantities of fuel (12,000 tonnes per day) are being designed for installation on floating offshore process vessels, having displacements over 300,000 tons. New, large capacity product tankers (250,000 dwt) are needed to transport product and floating power generation facilities over 500MW capacity are being planned for cities such as New York.

The paper describes the design of a floating 12,000 ton per day GTL facility to be deployed offshore West Africa, the transportation requirements, the design of a floating 520MW combined cycle power plant and overall economies for the generation of electricity for the US market.