bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure Probability Analysis Techniques for Long Mooring Lines
Authors: Flory J.F. , Hearle J.W.S. , Stonor Richard , Luo Yong
Published: October 2008

This paper describes statistical techniques for analyzing failure probabilities of long mooring lines. The long line is treated as a series of segments, each as long as the break or fatigue test specimens. Termination failure statistics are treated separately.

The analysis techniques are applicable to mooring lines comprised of chain, Wire, or fiber rope. They are also appropriate for long electrical and control cables, hoses, and umbilicals. Examples are given to illustrate the techniques.

INTRODUCTION

There is much interest in assessing the reliability of deepwater mooring systems.! Mooring lines are typically much longer than the short test specimens used in determining breakmg strength and fatigue life statistics. For example, each ofseveral mooring lines used on a floating platform in deep water might be over 1000 m (3000 ft) long, but the specimens used m break and fatigue testing might only be 10 m (30 ft) long., This paper addresses problems in relating break and fatigue test .data obtained from tests on short specimens to the reliability of the same type of line in very long lengths. It includes the effects of terminations with different statisticalproperties than the body of the line.

. "A chain is. only as strong as it's weakest link". For simplicity chain will be used as a model in this paper. The technique s also apply to wire and fiber ropes, in which performance IS determined from tests on short specimens and the ropes used in service are much longer. "Short rope" can be substituted for 'link', and long rope" can be substituted for 'chain' throughout this paper. Here the word termination means any component or method used to connect parts of the mooring line together or to connect the entire mooring line to a vessel or an anchor. Examples include chain connector links shackles and splices in wire or fiber rope. "

The probability of failure at any given load increases as the total line length and the number of terminations increase. Of course. It also depends on the mean strength and the strength variability of these components. If sufficient statistical data for the components are available, the analysis techniques described m this paper can be used to design a system with an acceptable risk of failure.

The prediction of reliability for a length of chain based on the statistics of individual links is first considered. The effects of terminations on the reliability of this length of chain areintroduced later.

STATISTICAL CONCEPTS

The Chain Link Model

A theoretical chain comprised of individual links is shown in Figure la. It is analogous to a long length of chain made upof shorter lengths equivalent to the test specimen length, as shown in Figure lb. It is also analogous to a long length of rope, again made up of shorter lengths equivalent to the test" specimen length, as shown in Figure lc.

The breaking strength of the long chain can be determined from the strengths of individual links.
Calculating Remaining Useful Life of Ships
Authors: Egan G.A. , Andrews B.V.
Published: October 2008

Recent developments of engineering analysis methods enable useful forecasts of physical life of ship hull structures, piping, and machinery. Economic analyses of the costs of rehabilitation and increasing maintenance costs can demonstrate that the useful life of tankers can be extended many years at significant savings over replacing 15- to 20year old vessels.

THE TANK SHIP OWNERS' OUESTION: VESSEL USEFUL LIFE?

The last two decades have been hectic for tank ship owners and their builders. Business and revenue boomed in the early 1970s, faltered in the mid-1970s, and rose again at thestart of the 1980s. Prospects crashed to depression by the mid-1980s and only now are returning to normal. Theproximate cause for these demand fluctuations were the double OPEC oil price shocks of 1973 and 1979 that caused worldwide economic disruptions.

Crude oil tankers, and especially the very large crude carriers (VLCC) and even larger tankers were being over orderedand over-built from 1968 to 1975. Then in 1973, the Persian Gulf OPEC countries raised prices from $3 to $13 per barrel for crude oil cutting oil transport demand quite sharply. Even though tanker capacity supply was suddenly about 35% excess over demand, more tankers were ordered later. As shown in Figure I, most of the VLCC/ULCCs (that represent about two-thirds of all tanker capacity) were delivered between 1973 to 1978(1).

Over 100 million deadweight tons (dwt) of tank ships were scrapped in the early 1980s to reduce the excess fleet. Crude oil prices have plummeted since 1986; therefore, demand has escalated and the gap between excess tanker supply and demand has narrowed. Ship charter hire rates have at last escalated to profitable levels for existing tankers for the first time in 20 years.

Since the last major ship orders in the late 1970s, extensive cuts have been made in the world shipbuilding industrycapacity. Few shipyards are now able to build large ships and are quoting increasingly high prices. (These prices should go up even more when state subsidies are discontinued by international agreement.) For example, a 1971 vintage VLCC that originally cost $15 to $20 million will now cost nearly $100 million to replace. If a double hull is required, the new building cost is over $110 million. Therefore, charter rates must increase even more to make profitable investment in expensive new tankers.

In summary, ship charter rates now are not adequate to pay for building and operating new tankers. In addition, not enough ships of each kind have been built in the last decade. As a result, economics forces most owners to keep using their existing ships longer than their typical 16- to 20-year life span.

BASIS FOR LIFE EXTENSION

During the last two decades, many tank ships and other vessels have been laid up or slow-steaming and extended porttimes, some for several years and in varying degrees of care. As a result, they have not been worked hard nor overstressed.
A Vertical Connection System To Attach Flexible Pipeline to a Subsea Manifold
Authors: Brandao Maxwell , Couto Paulo
Published: October 2008

This paper presents a vertical guidelineless system for connecting flexible pipelines to a subsea manifold. The system uses only field proven components and allows the operator to test many different installation methods. The installation tool may be run by cable or drill pipe. Hydraulic control is supplied by umbilical or through a ROV hot stab. Field test results will be used to determine the optimum installation methods and to optimize the equipment design that will establish a new generation of subsea connection system that is simpler, more reliable and cost effective.

INTRODUCTION

The vertical guidelineless connection system to attach flexible pipeline to subsea manifold has been developed as alternative to existingsystems which use horizontal connection and pull-in system.

The project was based on the deepwater guidelineless drilling and completion experience in Brazil, resulting an equipment fullycompatible with operational requirements for a dynamically positioned drilling vessel. The main system components are:Temporary Abandonment Base (TAB)Vertical Connection Module (VCM)Running and Connection Tool (RCT)

A prototype is being developed to simulate, in a field test, the actual conditions of thevarious installation methods, in order to obtain enough data feedback for future improvement.

INSTALLATION METHODS

For better understanding, the operation can be divided in two phases:(AVAILABLE IN FULL PAPER)

ABANDONMENT METHODS

Two temporary abandonment methods of the VCM and TAB were established. These methods depend onthe type of vessel involved in the abandonment operation, as described below:

Abandonment with DP drilling vessel

This method, illustrated in fig. 1, requires the VCM to run connected to the TAB. The running operation of the VCM!TAB is made by means of a cable passed over a side of the drilling vessel while the guidelineless Christmas Tree runs through the moon pool. This method is only applicable in the case that requires the use of a short flexible jumper between the satellite Christmas Tree and the manifold (less than 100 meters). The great advantage of this method is that there is no need to use the pipe lay vessel to accomplish a layaway operation. The use of short jumper can also introduce a new concept of subsea layout with the satellite wells very close to the manifold.

Abandonment with the pipelay vessel

This method of abandonment using a pipe lay vessel, illustrated in fig. 2, also requires the VCM to run connected to the TAB. The running operation of VCO/TAB is made by means of a cable operated by the vessel while the GLL Christmas Tree runs through the moon pool of the DP drilling vessel using the layaway methods. Therefore the VCM/TAB should be fully compatible with the handling conditions of the pipe lay vessels. This method is necessary for longer distances between the satellite Christmas Tree and the manifold but may be applicable to any distance.
An Assessment of Unmanned Lightweight Platforms for Satellite Field Development
Authors: Power K.M. , Ford J.T. , Tweedie J.A.
Published: October 2008

The use of subsea technology for small field (400 mmbbls) development is now well established. However, there are a number of technical and economic reasons for preferring platform completion to the subsea completion of offshore wells. It is possible to construct a fixed platform for the majority of water depths encountered in the North Sea but to compete on an economic basis with subsea development options the platform needs to be lightweight and capable of unmanned operation,

Although minimal platforms have been used extensively in the Gulf of Mexico over the past decade they have rarely bea used iu the North Sea. However, recently there has been growing interest in the application of these development techniques inthe North Sea.

The work presented in this paper, which is a summary of an MSC. Subsea Engineering thesis at Heriot-Watt University, utilised cost and technical information from Asean Brown Boveri (ABB) Global Engineering Ltd. to analyse the economic and technical feasibility of applying these development techniques in the North Sea. This study examines a range of lightweight platform designs which could be used as alternatives to subsea facilities and then compares, on a techno-economic basis, two specific types of platform and the subsea technique for a range of water depths and field sizes

Introduction

The primary goal of a North Sea operator, in the developmentof a field, is to maximise his return on investment. In an effort to achieve this he will investigate development techniques which will reduce capital expenditure and if possible accelerate production. However, he will also have a long term view and therefore technical considerations such as thefollowing in mind: maximum flexibility for future.

Expansion, maximum use of proven technology, minimizing production downtime and minimizing abandonment cost. Theapplication of these principles is particularly important in the development of marginal and sub-marginal fields.

The use of subsea technology for marginal field development is now well established, However, there are many advantagesof completing such wells above sea level from a platform. It is of course technically possible to produce via a conventional four legged fixed platform but to compete economically with subsea technology in these types of development the platform needs to be designed with minimal facilities and capable of Unmanned operation.

The purpose of this project was to determine whether 'minimalplatforms', and specifically the new tripod structures, are a viable alternative to subsea development techniques for marginrd fields in the British Sector of the North Sea.

For the purposes of this study marginal fields are defined asthose having reserves less than 100 mmbbls and submarginal fields less than 50 mmbbls.

DEVELOPMENT OPTIONS

The relative techno-economic merits of three development schemes for a satellite field were assessed.
Installation of an Internally Clad Pipeline Using the J-Lay Method
Authors: van der Heijden Harry , van der Butler Peter
Published: October 2008

A J-lay system for deep and shallow water application was built by HeereMac and used on SSCV Balder to install a 316 L internally clad pipeline in the Maui field offshore New Zealand. The paper describes investment justification, concept development, system specifications, as well as Maui project welding process selection and offshore experience gained with the system.

INTRODUCTION

HeereMac operate four of the five large Semi Submersible Crane Vessels (SSCV'S) which are sailing the world's seas. Their employment is basically limited to the super heavy lift market, of which the total volume, worldwide, is not sufficient to ensure an optimum utilization level of these vessels, and therefore HeereMac seek enhy to other market segments. At the same time HeereMac look for participation in the deepwater developments which start to emerge around the world. Deepwater construction projects require deepwater lift capability, and deepwater pipeline installation equipment, and HeereMac are preparing to offer this in a total package centered around its SSCV Balder. In 1991 HeereMac built and commissioned the world's first J-lay system, designed to the requirements of all deepwater projects which can be envisaged for the next decade. In addition, the system can handle SIUJ1OWwater pipelines, for the reason that Balder is to be bid for total constructionprojects involving heavy lift and pipelay work in remote areas all around the world, including those in shallow water (see figure 1).

The J-lay system was first used only recently on the Maui B to Maui A pipeline installation project offshore New Zealand, which presented three technical c.q. managerial hurdles :Constructing the J-lay system in a very tight schedule, with little room for experiments or mishaps.Applying the J-lay system in swell-dominated shallow water, which is the most difficult from an operational viewpoint.Welding 316 L internally clad carbon steel pipe in the 6G position.

Having to face these problems, and bearing in mind that the J-lay system was to be seen as a long term investment adequate for all the ext decade's projects, required a high level of quality and reliability incorporated in the design and construction. With specific rules for design and construction of such equipment lacking, HeereMac chose to have Lloyd's certify the system along the lines of the Code for Lifting Appliances, As far as the selection c.q. development of the welding procedures and equipment were concerned, the focus was mainly on reliability and quality reproducibility rather than on welding speed. This was permitted by the length of the Maui pipeline being only 15 km.

A description of the system development and specifications, development of the welding procedure and equipment, as well as operational experience from the Maui B pipeline project are now presented.

CONCEPT DEVELOPM17NT OF THE J-LAY SYSTEM

HeereMac's market approach philosophy, as stipulated in the introduction, led to two stringent design requirements to be incorporated in the J-lay system:
Horizontal Wells in a Steamdrive in the Midway Sunset Field
Authors: Carpenter D.E. , Dazet S.C.
Published: October 2008

Three horizontal wells have been drilled in a low pressure, mature steam drive at the D&E Unit of the Midway Sunset Field, Kern County, California. Simulation studies indicate that horizontal wells in thermal projects can increase recovery efficiency due to better a real sweep, accelerate production which improves the oil-steam ratio (OSR), shorten project life, and increase project profitability.

The D&E Unit was selected as a test site for horizontal wells because gravel packs were not required for sand control. Low reservoir pressures and moderately sorted, sub-rounded sands contribute to the success of slotted liner completions. The reservoir is composed of well sorted, thick turbidite sands which dip at about 45°. The first two wells were drilled at an oblique angle to dip with approximately 400' laterals. The third well was drilled on strike with slightly more than a 700' lateral. Radius of curvature is approximately 40'. The three wells were drilled as short radius horizontal wells due to well and lease spacing constraints. The short radius design allows the rod pump to be placed in the vertical section of the hde with minimal draw down sacrifice. The lowest point of the laterals is 10' above the oil-water contact. All wells are completed with dotted liners. The three horizontal wells cost 2-3 times more than vertical wells. Oil production rates increased 2-3 times more than vertical wells in the two wells with 400' laterals. The third well with a 700' lateral is more prolific with 6 times the production rate of a vertical well. At this time, the wells are too immature to accurately predict ultimate recovery. This paper will discuss the drilling and completion design of the wells, steam soak data, temperature logs in the horizontal section and current production results.

EXPECTED BENEFITS

Simulation work has shown that horizontal wells in thermal drives accelerate production and increase recovery efficiency by improving a real sweep1,3,4,5 Increased production rates are a result of longer completed intervals and the additional draw down derived from placing the wells at the base of pay. In 1986, Huang, et al1 indicated that project improvement derived from horizontal well development could be dramatic; simulation results predicted a 250 percent increase in initial production rate. The best ease in the simulation reduced project life from 15 to 7 years.

Other potential benefits include producing reserves between the oil-water contact and existing completions. Many existing wells were completed shallow to avoid penetrating the transition zone. Horizontal wells may be the most effective way to exploit this wedge of undeveloped reserves.

Vertical wells frequently suffer from production problems Stemming from steam entry into the wellbore. Steam entry may cause sanding, liner damage, and high casing pressures. Horizontal wells would not "steam out" until the steam drive is very mature, therefore remedial work maybe significantly reduced.
Bonded Three-Layered Epoxy Polyethylene Coating to Continuous Steel Coiled Tubing
Authors: Reuser H.C. , Plummer R.A. , Lanan G.A.
Published: October 2008

The continuous steel coiled tubing manufactured by the ERW induction process features a patented weld allowing for coiled steel flat strips to be milled into continuous lengths of finished tubing and wound onto reels. A coating line was specially configured to apply a bonded three layered epoxy polyethylene coating to the continuous coiled steel tubing in lengths up to 14,400 feet by the straight through endo process.

The coated steel tubing was used for high pressure utility lines positioned from a central offshore platform to satellite platforms and were bundled and laid simultaneously from a lay barge. The lines were successfully nstalled offshore in Mobile Bay, Alabama in July, 1991.

INTRODUCTION

Electronic Resistance Welded (ERW) tubing or pipe is manufactured in a continuous process at the pipe mill. For typical pipeline applications, however, this continuous pipe is cut into 40 foot lengths at the mill, coated, transported to the installation site and then welded back together in the field. Obvious efficiencies result if the pipe can be coated, transported and installed in continuous lengths.

Procedures for manufacturing and handling continuous lengths of pipe are well established in the coiled tubing industry. Additionally, the offshore pipeline industry has developed procedures for installing continuous pipe lengths by the reel barge method. This paper describes the combination of these proven tubing/pipeline industry procedures with the continuous application of a high quality coating suitable for offshore pipelines. The continuous steel coiled tubing manufacture is described first, followed by the coating application, and a case history of its use in Mobile Bay, Alabama (Reference 1).

TUBING MANUFACTURE

Stee1 Coiled Tuber Development Modern coiled tubing technology was first applied in 1969, when l/2 in. OD tubing was used in conjunction with gaseous nitrogen to backwash salt water disposal wells. Since then, available tubing diameters have increased from 1/2 in. to 2 3/8 in. OD.

Coiled tubing trucks and skid units capable of running various sizes and lengths are now located in almost every oil and gas producing area of the world. There are presently more than thirty different downhole and fluid flow types of applications for coiled tubing. These applications now include offshore utility lines.

Stee1 Selection and Coil Slitting

Master coils of steel sheet are received from the steel mill in ten standard thicknesses ranging from 0.067 in. to 0.188 in. Coil lengths for the thinnest and thickest gauges vary from 3,800 feet to 1,800 feet, respectively, and the average coiled weight is 43,000 lbs. Each master coil is identified by a coil number and steel heat number. Individual strips slit from the master coils can be traced to the master coil number throughout the manufacturing process and delivery to the customer. Quality assurance and control is a vital tubing manufacturing function and follows both the welding and mill process to conclusion.
How To Find Gold (and Other Money) With a Dynamic Positioning Control System
Authors: Craft D.C.
Published: October 2008

An informal account of the first U.S. conversion of a standard tug/supply vessel into a Dynamic Positioned (DP) project vessel. Contains a limited review of deepwater search and recovery and the circumstances leading to the conversion. Concludes with a comparison of costs of chartering an existing DP vessel versus converting a vessel of opportunity.

TEXT

I had all but forgotten that the modifying of a tug/supply with a DP control system for the Central America Identification Project In 1987 was the first such effort in the United States.

I hope to give you some insight as to why and how this occurred. I believe that some of you here today may be able to save a considerable amount of operational money by taking a similar approach when the time comes to select a DP vessel for your future projects.

While preparing the original abstract for this presentation, a 9entleman I greatly respect recommended I Include a little of the development of Dynamic Positioning and bits of my personal deep water search aridrecovery experience, in his words, this would add flavor and interest to an otherwise boring subject. I hope he iS right

Let me point out for those of You that were not around In "good old days", before DP vessels were readily available, precise stationkeeplng for deep water work was completely dependent upon the shiphandling ability of a vessels master and/or mates. The technique required that a device be placed on the bridge to show the ship handler the vessels actual and real time position In relation to the desired position.

In reasonable weather conditions a good shiphandler would have little difficulty using this method to take up and maintain a desired position.

[Unfortunately the weather is not always favorable and the level of concentration required to maintain a precise station for long periods of time can be quite exhausting.

Under these conditions, as operator fatigue sets in, errors in judgement and reflexes could insidiously creep in with the result that the ship might make a totally unexpected or radical departure from station while equipment was deployed.

Such a departure can be very hazardous, even life threatening to personnel. It can also severely damage or bring about the loss of very expensive equipment. Seeking ways to prevent such accidents led, to greater and greater use of automation to augment the shiphandler's capability.

You will note that I use the word "augment" as opposed to "replace" the shlphandler. In my judgement nothing can replace a highly-skilled and competent shlphandler. I strongly feel that such an individual must always be the bridge of any deep recovery vessel, including' those with a fu: redundant DP control system.

Long before DP vessels became commonplace, I had twice gone through the pressure cooker of attempting to keep a vessel on a very small diameter station by "chasing the X" on a track plotter or TV type display designed by a non-shiphandling electronics technician.
The Corporate Safety Culture: Its Workings And Its Importance
Authors: Koenig D.W.
Published: October 2008

Corporate culture determines the vitality of an organization. The corporate safety culture is a subset of the corporate culture. Each corporate culture and each safety culture is unique

A culture is difficult to describe by people both inside and outside the culture, The reason for this is that people inside the culture are generally not conscious of it and people outside the culture describe it in terms of their paradigms.

This paper describes four components of culture: symbols, heroes, rituals and values. These components are applied to the early years of the Du Pent and Conoco companies as examples of how safety cultures develop. These cultural components are then applied to the Du Pont company of today.

Understanding why and how corporate cultures exist provides insight into why organizations function the way they do and how these functions can be changed.

The reader is asked to compare his organization's safety culture to that of Du Pent and Conoco in order to apply the cultural components and note similarities and differences.

INTRODUCTION

What are your first thoughts about the words, "multipe explosions, fire, and smoke"? The odds are your mind immediately focused on one of the serious incidents in the petroleum or chemical industries. But you could have thought about a recreational activity like a racetrack and a finely tuned dragster warming up at the starting line to go 200 miles per hour.

Do you ever wonder why the company you work for operates the way it does? Questions you might ask are: Why is the company concerned with safety or ethics? Why is the company concerned with occupational health or the environment? You might conclude that it's just the way things are done.

These questions tend to focus thinking on corporate behavior and how individual interpretations of an event can differ or be the same. The interpretation an individual lives to an event is a result of that individual's socialization into a culture1.

This paper focuses on one of several levels of culture the organizational or corporate culture. Geert Hofsted in his book Culture and Organizations describes six cultural levels: 1. a national level, 2. a regional, ethnic or religious level, 3. a gender level, 4. a generation level 5. a social class level, and 6. the organizational or corporate level2.

The content of this paper is taken from three major sources: recent business literature on corporate culture, examples from the Du Pent and Conoco safety cultures, and personal interpretation,

This paper hopes to pique your interest in ways to understand corporate safety culture. It represents a personal view of safety and cultural issues. The observations I make about the safety culture of my organization are made from my own set of paradigms

Paradigms are the rules people use to solve problems. Paradigms work well for as long as they fit the conditions of the problem. Steven Covey describes it this way in his book The Seven Principles of Highly Effective People:
Deepsea Mining In China
Authors: Xie Longshui
Published: October 2008

At present, the ore reserves per man in China is 1.5t, much less than 3.5t which is the average ore reserves per man in the world. With the development of China national economic construction, the requirement for copper, nickel, cobalt and manganese to China's industries is being increased gradually, Currently, the supply of these metals is short of demand in China, and this shortage is filled up through the import of mineral products from other countries, Thus the polymetallic nodule mining in deep sea is of great importance to China national economic construction, This paper describes the situation of China's metals market, the early study on deep sea mining, the existing conditions of the exploitation of deep sea polymetallic nodules in China up to date, and the general situation of China Ocean Mineral Resources Research and Development Association (COMRA). From the point of the author's view, the deep sea mining plan and the technical strategy to achieve the aim of industrial mining in the registered international seabed nodule area early in the next century taken by a China ocean mining entity are described in the last section of this paper.

INTRODUCTION

The increasing development of today's Industry leads the demand for metals to great increase inevitably. With the ever decreasing of the land mineral resources, the wish for obtaining the ore from oceans becomes more eager. Therefore, the seafloor in the future will be a base of raw metal supply to the world industries.

Early in 1960s'the assessment of nodule mineral resources in the seafloor was made by J. L. Mere, Professor in a university in U.S.A. Since then, it is increasingly acknowledged that the manganese nodules in the seafloor are said to be a new mineral resources Meanwhile, the surveying of seabed manganese nodules was started in many countries.

Up to now, a great progress in the research and development of seabed manganese nodules has been extended, especially in U.S.A., Germany, France, Japan and former USSR etc. Without any exception, a great achievement in the surveying of seabed manganese nodules had been made by China(the 5th pioneer investor of deep sea mining fol. lowing on India, former USSR, France and Japan, which was approved by the Preparatory. Commission for the International Seabed Authority officially in March 1991),

According to the surveying, the manganese nodules distribute over the deep seabed, especially concentrating in the Pacific ocean, Of course, it is very difficult to collect the manganese nodules in such a deep sea. this is a systematic engineering involved in many disciplines such as geology, oceanography, metallurgy, electronics, shipbuilding, mechanics, computer supervisor y control, underwater TV, remote control, new materials,. and new technology etc. In order to make the exploitation and utilization of ocean mineral resources possessed of human race be true as soon as possible, the deep sea mining sector of China is willing to cooperate with he international entities to research in the mining, processing and metallurgy technology. for manganese nodules.
High-Resolution Seismic Stratigraphic Applications To Petroleum Exploration
Authors: Trabant P.K.
Published: October 2008

High STAND SYSTEMS TRACT (HST) AND CONDENSED SECTION (CS)

The sequence stratigraphic cycle starts towards the end of a high stand in sea level as experienced under present day conditions. sediments accumulated during this period of the cycle are part of the highstand systems tract ([1ST)of Figs, 2 and 3.

During the HST stage there is very little deposition on the outer Continental shelf and beneath the deeper water of the slope, as sediment accumulation consists Primary in a slow "rain" of microscopic shells of plankton and other fossils and wind transported sediments, The slow accumulation of sediments during this phase the cycle is "condensed" relative to time, and it is the condensed layer tire identified on high resolution seismic records by laterally continuous strong acoustic reflection and the attitude of overlying und underling reflector (Fig 1 and 5). The point in time at which sea level reaches its Maximum incursion shoreward is referred to as the "maximum flooding stage" (mfs of Figs 2 and 3). This occurs during the warmest portions of an interglacial stage, and the resulting sediment layers are characterized by an abundance of microfossils.

A "sequence boundary" is located immediately above the condensed section provided no erosion has taken place, in which case the boundary follows the unconformity.

High rates of sediment accumulation during the HST phase are limited to points of high fluvial discharge along the shoreline and the occasional delta which builds out onto the shelf. Such is the case at the mouth of the present-day Mississippi River. The HST portion of a cycle is completed when sea level drops sufficiently to place the shoreline along the outer portions of the continental shelf As the cycle progresses the shoreward areas become exposed and dissected by fluvial processes developing a coastal plain similar to the present-day areas of south Texas and Louisiana,

SHELF MARGIN SYSTEMS TRACT (SMST)

As sea level drops as a result of global climatic cooling and the buildup of continental ice sheets the shore line slowly migrates towards the outer continental shelf accumulating sediments seaward where supplied in a "prograding"fashion [Fig. 3),

Those areas experiencing high sediment discharge rates on the mid to outer shelf areas develop shelf margin systems tracts (SMST), while elsewhere relatively little deposition takes place.

The SMST depo-centers consists of lobe-shaped sedimentary complexes which tend to meander and switch position along the shoreline or shelf edge during this period.

Upon reaching the shelf edge with a further drop in sea level sediments are dumped down the steeper inclines of the upper slope to form the lowstand systems tract components of Figs. 2 and 3.

LOWSTAND SYSTEMS TRACT (LST)

Upon reaching it's lowest elevation towards the peak of an ice age, sea level and the shoreline are located along the continental shelf edge. This is more than a hundred miles off the present Texas coast in approximately 500 feet of water.
Offshore Pipeline Welding For Cats Project
Authors: Ibarra S. , Pronko M. , Grass G.D. , Hostler F. , Hutchens E.J.
Published: October 2008

This paper presents some of the challenges encountered during the welding of the Amoco CATS pipeline. The 36-in. diameter high pressure gas pipeline was installed from an onshore terminal at Teesside, England to the North Everest Riser Platform located in the Central Graben Development Area in the North Sea. The off- shore pipeline was installed by McDermott/ETPM using the lay barge LB200. Submerged arc welding (SAW.) was used for the double joints and ETPM's proprietary Saturne 8T gas metal-arc welding (GMA W) system for both the mainline welds and the root pass of the double-joint welds. The CATS pipeline has undergone rigorous testing, not only when the line pipe was being fabricated, but also when establishing welding procedures and throughout the pipelaying process. This rigorous testing and monitoring has resulted in a pipeline of very high quality.

INTRODUCTION

A two-year pipelaying program has been completed in the North Sea, using primarily automatic GMAW techniques. The CATS Pipeline and Riser Platform was installed to join the gas fields in the North Sea to the industrial area of Teesside, England as shown in Fig. 1. A power generating plant is being completed, and other industries in the Northern sector of England will benefit from this gas. The total length of the pipeline is 404.5 km (251,3 miles) and the riser length is 115 meters. The pipeline is 36 in. in diameter, API 5L Grade X65 fabricated with double submerged arc welds to form the longitudinal seams. The wall thickness was 28.4 mm (1 .12 in.) with a small portion 33.9 mm (1 .33 in,) wall thickness at onshore and shore approach sections. The line was designed for dry sour service. The design pressure is 2600 psig with a 1500 ppm/4 psi max. hydrogen sulfide. The design oxygen content was 10 ppm/0.03 psia max. and the carbon dioxide was 25 mol%A/654 psia max.

LINE PIPE MATERIAL

The line pipe was fabricated by Mannesmann to conform to sour service performance requirements. The CATS pipeline represented an order for 260,000 tons of steel. The technical requirements for the line pipe were based on the API 5L specification for line pipe1 with certain additions, deletions, and modification made to conform to Amoco requirements with mutually agreed manufacturing Iimits2. For example, the product analysis chemistry of the pipe material was subject to the limits shown in Table 1. The two carbon equivalent measurements specified were the IIW and Pcm suchthat:(Mathematical equation available in full paper)

Charpy V-notch impact testing was also modified from API 5L requirements to state that a set of three specimens would be taken from a pipe from each heat, transverse to the weld, from each of the following locations:Weld Metal - Notched on weld centerlineHeat Affected Zone - Fusion line centered on(HAZ) notchBase Metal - Notch on base metal

It was also stated that the top of the Charpy V-notch specimen would be taken 2 mm from the outside pipe surface. The acceptance criteria for the toughness are shown in Table 2.
Troll Oil Development Concept
Authors: Prydz Rolf
Published: October 2008

Underneath the large gas accumulation of the Troll field lies a considerable volume of oil. However, its development requires an innovative approach because it is located in thin layers sandwiched between a large gas cap and an active aquifer. During the past 4 years Norsk Hydro has carried out extensive technical studies and an ambitious seismic acquisition and appraisal well programme to identify an economic development concept for the oil resource. This has resulted in the submission of a development plan for an extensive subsea development based on horizontally completed wells which will be manifolded on the seabed and tied back to a concrete semi-submersible production platform.

INTRODUCTION

The Troll field is located on the Norwegian Continental Shelf in 315-340m of water 100 km NW of Bergen as shown in Figure 1. It is covered by production Iicences PL054 and PL085 which are unitized. The owners of the field and their individual percentages are shown in Table 1.

In December 1991 the Troll Licensees submitted a Plan For Development and Operation (PDO) for the oil resources of the Troll Field. The plan marked a successful milestone in the extensive development study and appraisal well activities carried out by the operator, Norsk Hydro since 1988. The proposed development concept consisted of 17 horizontal subsea wells tied back in groups to a concrete floating production platform. A schematic of the PDO concept is shown in Figure 2.

The PDO was approved by the Norwegian Parliament in May 1992 and during this year and the first quarter of 1993 the operator built up a multi-discipline project team and completed basic engineering and part of the detailed engineering phase. Contracts were awarded for topside facilities design, the subsea production facilities and the production unit living quarters. Detail design of the concrete substructure is in progress and a drilling rig will be contracted medio 1993 to carry out the 3–4 year development well drilling programme.

This paper describes the work done to select a development concept for the North Sea's most ambitious subsea project to date, and the changes that have been made to the original plan as a result of subsequent, more detailed work.

TROLL FIELD APPRAISAL HISTORY

The Troll Field was discovered in 1979 by exploration well 31/2-1. This well was drilled on the crest of the large gas structure of Troll West. By the end of 1984 a total of 15 wells had been drilled on Troll West confirming it to be a significant discovery.

In addition to the large quantities of gas the appraisal programme also confirmed the presence of significant quantities of oil below the gas. However, the oil is contained in thin layers which are distributed over a wide area. Development of the oil layers was considered complex and uncertain commercially, therefore development planning activities concentrated on the large gas resource.
Rapid Deployment CALM 6uoy System
Authors: Lorentz John
Published: October 2008

The design, fabrication and installation of a Rapid Deployment Catenary Anchor Leg Mooring (CALM) Buoy from an anchor handling tug combined proven technology with innovative designs and novel equipment developments. This paper describes the design requirements, development and trial installation that was successfully conducted as well as possible applications for this unique system.

INTRODUCTION

IMODCO was awarded a contract in March 1990 to design a CALM buoy system to be used in support of military action and be light and compact enough to be loaded aboard a typical North Sea-type Anchor Handling Tug (AHT) and installed without the luxury of typical oilfield equipment or divers, The proof of the ability to achieve this goal was the successful deployment and recovery of the system in October 1990.

DESIGN AND FABRICATION

Typically, a CALM buoy may be 11 to 12.5 meters in diameter and weigh up to 210 tonnes. Such a buoy must support large diameter piping, six chain legs up to 108 mm diameter and with stand maximum chain loads of 280 tonnes while mooring VLCC'S of high cargo throughput (50,000 bbls/hr). The targeted size and weight of the Rapid Deployment buoy was approximately one fourth of that stated above.

Although the basic design method utilized in the mooring analysis and structural calculations for this project were not unique, the design of a buoy and chain system that could be transported and handled within an area of such restricted size presented a challenge. The maximum specified tanker size of 50,000 DWT and the Client requirement for only one (1) throughput product resulted in significant buoy weight and diameter reduction. Further weight reduction of the buoy hull and framing was achieved by using 50D type steel with a yield strength of 345 N/mm2.

Considering the intermittent service and limited duration of use that the system would see, the buoy framing was optimized to result in exterior hull plating thickness of 8 mm and interior bulkhead plate thickness of 6 mm, whereas Lloyd's normally requires a minimum thickness of 905 mm for continuous service.

The method of buoy launch from and recovery aboard the AHT involved discussion of many concepts including the construction of complex launch ramps or sliding frames or simple buoywelded skids with an array of pulling wires. Since available deck space was at a premium, the decision was made to concentrate on a method of handling the buoy over the AHT stern roller using only AHT available rigging and winches. On deployment, the buoy would be pulled over the stern as a continuation of laying the first chain leg, Rigging leading back to the AHT winches would provide stability and control and prevent the buoy from tipping, On recovery, pulling wires and mooring chain would provide sufficient force and stabilization to bring the buoy up and over the stern roller.
Cadlao's Successful Fpso Ii Redeployed At The Deepwater West Linapacon Field
Authors: Genod Francis Vincent , Jeannin Olivier
Published: October 2008

The number of FPSO's installed on marginal Fields k increasing while the life of these Fields is often unpredictable. The possibility that a tanker-based FPSO may easily be relocated after depletion of a marginal field may become a key factor to the decision making process in respect of small field development.

This paper will describe the circumstances under which the tanker-based "FPSO II" was disconnected from the Cadlao Field in the Philippines (after 10 years and 3 months uninterrupted operation), towed to Singapore, for refurbishment and modification, towed back to the Philippines and installed on the new West Linapacan Field in a water depth of 1150 ft. The Scope of Work included the replacement of over 800 tonnes structural steel in the tanker, extensive work on the process equipment and instrumentation plus a comprehensive refurbishment programme for the SBS mooring system and the vessel machinery.

The whole project was executed under very tight time constraints and less than 6 months elapsed between last oil at Cadlao and first oil at West Linapacan.

HISTORY

The 127,000 dwt converted tanker FPSO II owned and operated by SBM Inc. went into operation on the Cadlao Field, offshore Philippines in August 1981. This Field in 300 ft water depth was produced through 611flowlines from 2 wells. Each well was also connected to 611service lines thus requiring a 4 path 611 swivel mounted on the SBS mooring buoy. The SBS mooring buoy was attached to piles driven in the sea bed by six 611 ? 5½11diam. chains. The production facilities mounted on the tanker deck were designed to handle 30,000 BPD oil and a ground flare was installed to flare up to 6.5 MMCFD excess gas.

The 3-phase production and test separators also removed the produced water which was passed through a skimmer/degasser to 2 series operated slops tanks where it was de-oiled and pumped overboard. The design and operation of the FPSO II on the Cadlao Field has been extensive y reported in various publications.1–6Fig. 1 shows the FPSO II operational configuration in the Cadlao Field.

In 1986, the Cadlao Field concession was ceded to Alcorn who had also obtained the Matinloc Field concession situated nearby. A new bare-boat charter was negotiated for the FPSO 11 and the Matinloc Field then connected to it. This required modifications to the production manifolding and the installation of a metering/prover loop system on the FPSO 11 to fiscalize the Matinloc crude.

This mode of operation continued until November 1991 when the production had fallen to an uneconomic level and it was decided to relocate the FPSO 11 to West Linapacan Field.

During its 10 year operation in this area the FPSO 11 had a remarkable record of having virtually no down time.

LINAPACAN FIELD

Fig.2 shows the location of the West Linapacan Field situated in 1150 ft water depth 55 km from the Palawan Island coast.