bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Ni Alloy (Type 825) Clad Pipe Manufactured by UOE Process
Authors: Tsuji M. , Kobayashi Y. , Suga M. , Urne K. , Torna H. , toh M. 
Published: October 2008

ABSTRACT
About 3000 tons of 42%Ni alloy clad X65 UOE pipes were manufactured by two manufacturing processes; application of TMCP to clad plate rolling without pipe heat treatment and as-quenching type heat treatment on the clad pipe. In both processes, use of low carbon materials as clad metal and backing steel achieved high corrosion resistance and good mechanical properties.

INTRODUCTION
As development of oil or natural gas in deep sour well have been active in recent years, the use of corrosion resistant alloy line pipes is increasing. Duplex stainless steel pipe is successfully used for the transportation of corrosive liquid containing CO2-Cl in the North Sea1), Alaska2) and outlier places. Coping with the demands for corrosion resistant alloy pipes, manufacturing procedures and properties of five kinds of corrosion resistant alloy solid pipes were standardized as API Spec. 5LC in 1988. Transportation of oil and gases containing H2S requires use of high Ni alloy pipe from the aspect of corrosion resistance. However low yield strength of the high Ni alloys increases wall thickness of solid alloy pipes, which results in a large increase of material cost. Therefore, high Ni alloy clad pipe, which consists of the inner layer of high Ni alloy and the backing layer of high strength carbon steel, deserves much attention because of its economical configuration.
Under the circumstances mentioned above, manufacturing technologies of internal clad pipe have been developed through the UOE process using high Ni alloy clad plate rolled in integrated processes. The girth welding and induction hot-bending technologies have been also established. Using those manufacturing technologies, about 3000 tons of 42%Ni alloy-clad X65 pipe for submarine pipeline were recently produced.
In the present paper are introduced the corrosion resistance of 42%Ni alloy, manufacturing technologies and production results of the pipe. Test results of the girth welding and the induction hot-bending of the clad pipe are also described.

CORROSION RESISTANCE OF 42%NI ALLOY
High CO2 contents in aqueous liquids cause rapid weight loss type corrosion and the corrosion loss is increased as service temperature is high. The Cr content of the alloy is essential to improve the corrosion resistance in CO2 or CO2-Cl environments. Therefore, l3%Cr martensite stainless steel and 22%Cr or 25%Cr duplex stainless steel will be selected for use in such environment. The duplex stainless steel can be used for higher temperature service because of their higher Cr content.
The presence of H2S causes sulfide stress corrosion cracking in martensite stainless steel and duplex stainless steel. Another effect of H2S is to exacerbate chloride stress corrosion cracking (SCC) at high temperatures. On the contrary, high Ni alloys are generally characterized by good corrosion resistance in non-oxidizing acids and SCC resistance in Cl containing solutions at high temperatures.
The Oseberg Reservoir Management Planning: A Case History From the Oseberg Field
Authors: Torvund T. 
Published: October 2008

ABSTRACT
The Norwegian Oseberg Field came on stream in December 1988. The reserve estimate for the field is currently 209 million Sm3 (3.31 billion stb) of oil and 92 billion Sm3 (3.25 TScf) of gas.
The reservoir management planning prior to production start up has focused on optimizing the original production plan for the Oseberg reservoirs and investigate dynamically key elements in the plan in several long-term reservoir tests.
This paper demonstrates reservoir management as a key element in the process of optimization of offshore developments and the importance of having some flexibility in the development plan to accommodate new knowledge and new technology.

INTRODUCTION
The main factors influencing an offshore field's profitability is the geology and reservoir conditions, the development solution and the oil price. While the price remains uncertain throughout the life of the field, the development solution is traditionally decided while there still is much uncertainty as to the interpretation of how the reservoir will behave during production.
Important reservoir aspects are at this stage inferred from extrapolation of static data obtained during drilling, short drill-stem tests and from geological and geophysical work. More accurate knowledge of reservoir behavior is typically obtained after regular production has started, when dynamic reservoir information is being gained.
In such a situation where much uncertainty exists it is important to give the development solution flexibility for possible adjustments to cost-effective improvements. It is equally important to actively search for new information about the reservoir that may lead to improvements in the plan and in the production operations.
The Oseberg Field is a major oil field located in the Norwegian part of the North Sea. The field was discovered in 1979. The Field Development Plan of the Oseberg Field was decided in the end of 1983. From then and until the production start-up in December 1988, the Plan has seen two significant modifications which both have originated from the process of optimizing the reservoir management of the field.The production mechanism of one of the major structures has been altered from water injection to gas injection to increase recovery. This has been made possible by import of unprocessed gas from the giant Troll East Field.The average production capacity from the field has increased from 204.000 to 340.000 stb/d.
In addition, a long-term reservoir test has taken place, which not only has provided valuable dynamic information about the reservoir prior to regular production, but also given income to the Oseberg owners.
This paper will give an outline of the reservoir management planning process for Oseberg. The background for and the consequences to reservoir management by the improvements to the development plan and by the long term-reservoir test will be presented
Operational Limitations of Offshore Crane Vessels
Authors: Clauss G.F. , Riekert T. 
Published: October 2008

ABSTRACT
The paper analyzes the limiting conditions of crane vessel operations with special emphasis on large semisubmersibles. As reference structures a barge with 500 t crane capacity, a ship with 1,800 t capacity and a semisubmersible with two revolving 6,000 t cranes, are investigated. Model tests in irregular seas and specific wave groups demonstrate the significance of coupled resonance motions of vessel and suspended load for crane operations with semisubmersibles. 'With barges and ships resonance is of minor in1.portance due to high damping.
The mass of the suspended load and the sling length are decisive parameters for the motion characteristics of crane vessels. The transfer function of the vertical load motion, which is selected as limiting quantity, has been determined experimentally for each of the three vessels. Depending on this parameter and the maximum allowable load motion the limiting wave heights for crane vessel operations are compiled.

INTRODUCTION
Offshore oil production in deeper and more hostile locations of the North Sea will require an investment of $15 to $20 for each barrel of future oil output. Consequently, the crude oil price collapse in 1986 - taking the value of a barrel of Brent oil down to $10 - stopped most industrial developments. The challenge, however, also provoked new ideas and concepts like floating production systems, compliant structures and light-weight platforms. A major incentive for economic field developments was the advent of giant crane vessels. With maximum load capacities of up to 14,000 tollS complete jackets, topsides, foundations, templates etc. can bc installed or removed, mostly by tandem crane operations. Installation costs are reduced up to 40 percent as the saving on steel for "slimline" jackets amounts to 20 perccnt in relation to the conventional launching method. Even greater stec1 weight savings - up to 40 percent - are being made by constructing an integrated deck rather than building a series of modules in individual shipyards [1-8]. further, offshore work requirements - costing five times more than for the same work onshore - are reduced considerably, testing and commissioning of platform decks is accomplished onshore and weather window limitations are less significant. Based on data of 2nd, 3rd and 4th-Generation North Sea platforms Vugts [9] estimates substantial cost savings by favouring an installation by crane vessc1 above traditional launching (Fig. 1).
Fig. 2 presents some data of semisubmersible crane vessels (SSCV), ships or barges [10]. N'ote the dramatic increase of lifting capacity. Amazingly just the load sensitive scmisubmersibles made thc running. Of course, thcir excellent motion behaviour in the seaway is a major advantage and sheer size with options for two cranes of large load capacity, outreach and lifting height combined with a flexible ballasting system outmatches other concepts in delicate offshore lifting operations.
Multibeam Swath Surveying: A New Opportunity
Authors: Bennett J.D. 
Published: October 2008

Abstract
The recent development of a new generation of shallow and deep water multi-beam echo sounders will enhance exploration and production in water depths up to and beyond 1000 meters.
They will also enable many established and developing countries to assess and develop resources contained within their Exclusive Economic Zone's (EEZ's), both on the continental shelf and to full ocean depth.
Multi-beam echo sounders are set to revolutionize the world of ocean charting. Instead of collecting sparse amounts of data in single lines of soundings, by utilizing a multi-beam sonar, large areas of seabed can be surveyed equivalent to a swath of twice the water depth, with a contoured chart being available in real time. Several sonars are available on the market, all of which significantly reduce the ship time required to conduct seabed charting, whilst at the same time contributing to an overall increase in the quality of the final chart.
This paper identifies the potential in the fitment of such a sonar to an ocean going ship to chart specific exploration areas or the recently created EEZ's and also in the provision of a complete Hydrographic and oceanographic service which will be available to the Commercial and Research communities.

1 INTRODUCTION
Deep water oil and gas exploration is a growing area as shallow water sedimentary basins become exhausted and oil companies turn to deep waters. Having located oil and gas for production, further surveys are required to enable the laying of deep water installations and pipelines.
Any exploration work requires cood seabed charting and swath sonars are able to chart large areas of the seabed, both on the continental shelf and at full ocean depth, in a cost effective manner.
As we develop the capability to work in deeper waters, the exploration and exploitation of Exclusive Economic Zones (EEZ's) becomes more feasible. The United Nations Convention on the Law of the Sea in 1982 defined certain exclusive rights of coastal States, out to 200 miles or more from their coastlines.
During the next decade and into the early part of the 21st Century, the need for reliable surveys of the EEZ'swill increase rapidly as countries seek to exploit the diverse range of living, mineral and energy giving resources contained within them. The importance of well planned, efficient, effective and environmentally sympathetic development of these EEZ' s must not be underestimated. EEZ 's cover almost 40% of the Seas and Oceans; they are crucial for the survival of mankind and we must avoid polluting and destroying their sensitive ecosystems in the current search for relatively short term material gains. Thus, to be able to plan, manage and police the necessary activities in EEZ waters, high quality governments as being the first requirement.
A Procedure To Evaluate Pile Drivability in the Difficult Soil Conditions of the Southern Part of the Gulf of Guinea
Authors: Puech A. , Poulet D. , Boisard P. 
Published: October 2008

ABSTRACT
This paper presents a method for evaluating the soil resistance to driving in the hard clays, very dense sands and rock strata encountered offshore Angola. The method is calibrated on typical case histories where 48" O.D. platform piles and 30" .D. conductor pipes were instrumented during driving. Results are applicable on most of the oil fields located in the southern part of the continental shelf of the Gulf of Guinea.

INTRODUCTION
The Gulf of Guinea is a zone of intense oil field developments. In the southern part of the Gulf, i.e. roughly south of the equator line, the continental shelf consists of a narrow band (50 to 100km wide) extending from Cap Lopez (Gabon) to Moss Medes (Angola) (Fig. 1). The water depth increases gently from 20 to 200m from east to west then dips suddenly to 1000m. The zone is characterized by a common geological history. The submarine canyon of the Congo river is the only outstanding topographic accident.
In the past few years, several oil companies had to face serious platform installation problems due to major difficulties encountered during pile driving operations. Three types of problems have been identified:development of strong set-up effects in hard clays during add-on welding,premature refusal of piles in very dense sands,collapse of pile toes on limestone layers.
The paper addresses these different topics and presents a procedure to predict the soil resistance to driving in the specific soil conditions of the region. The method is based on the experience gained during the first phase of development of oil fields located offshore Angola and operated by ELF AQUITAINE. Its application may be extended to the southern part of the continental shelf of the Gulf of Guinea, wherever quite similar subsurface soil conditions prevail (South Gabon, offshore Congo, offshore Cabinda).

EVALUATION OF DRIVING HAZARDS
The development of Block 3, offshore Angola, started in 1985. Four jacket-type platforms have been installed so far in water depths ranging from 65 to 90m. They were founded on 48" O.D. steel pipe piles driven by hammers with rated energies up to 700 kJ (500 000 ft.lbs). The wall thickness of the piles was comprised between 1" and 2". The 30" O.D. conductor pipes were also installed by driving.
Premature refusals of piles and/or conductor pipes were observed during the installation of the first two platforms. Obviously, these difficulties were due to local specificities in the soil conditions:
high degree of heterogeneity of the soil formations, presence of limestone layers with a random distribution, unusual response of some materials to dynamic sollicitations
End Bearing Capacity of Piles in Calcareous Sands
Authors: Golightly C.R. , Nauroy J-F. 
Published: October 2008

ABSTRACT
In this study, laboratory tests simulating the end-bearing of piles founded in silica sand and two calcareous sands at different densities were conducted. Bearing capacities are compared with field test values and theoretical cavity expansion pressures. Limit values for end-bearing based upon compressibility are suggested.

INTRODUCTION
The end-bearing capacity of deep foundations in sand is a complex and poorly understood subject. No recommendations exist which have been proposed by the certification authorities for more compressible sands of different mineralogy notably the biogenic calcium carbonate (calcareous) sands found mostly, although not exclusively, on continental shelves in tropical and sub-tropical regions. Pub1ications within the 1ast fifteen years have shown that pile capacities in such materials are much lower than in silica sands at similar relative densities.
This paper presents the results of model pile axial load tests carried out in a calibration chamber upon a silica sand and two incremented calcareous sands in dense and loose states. The laboratory results are then compared with published field test data and suggested design values are proposed.
Current Methods of Determining End-Bearing Current guidelines for offshore pile design in silica sands (API, 1989) are based upon an extensive back-analysis of pile load tests at penetrations of up to 30m (Dennis and Olson, 1983). Unit end-bearing is expressed as : (MATHEMATICAL EQUATION AVAILABLE IN FULL PAPER)
Where ?y' is the effective overburden pressure and is a bearing capacity factor. It has long been recognized that does not increase linearly with depth, but that the rate of increase reduces with depth. Limiting values used in design are equivalent to values of from equation (1) at an effective overburden pressure of approximately 240 kPa. Another approach includes an empirical method based upon high quality pile load tests, (Coyle and Castello, 1981) avoiding the use of limit values, which is [I1ore realistic, but taking no account of effective stress levels, being in terms of relative penetration. Another method (Randolph, 1985) links qp to Nq using recent correlations which properly model reductions in friction angle with mean effective stress. No recommendations exist in the API guidelines for more compressible sands, although research carried out on behalf of API (Dennis and Olson, 1983) equates medium dense ca1careous sand with loose silica sand and loose calcareous sand with very loose silica sand. A semi empirica1 method (Nauroy et a1., 1986) 1inks unit end-bearing to compressibility and proposes limiting values of qp related to the value of a compressibility index
Major Steel Renewals in FPSa Ballast Tanks Without Ceasing Production
Authors: Nelson P. 
Published: October 2008

ABSTRACT
The number of tanker-based floating production systems and floating storage units in service is increasing. These are often based on older tankers in which the effects of corrosion, particularly in ballast tanks, increases with time. This paper explains why major steel renewals were required in one particular FPSO, the tanker of which was built in 1968. The methods and procedures described should give operators more confidence in repairing their units offshore without shutting down production or taking their vessels out of service.

INTRODUCTION
Tanker-based floating production and storage systems were introduced in the late 70's. They have proved to be fully effective and extremely reliable. Downtime on two FPSOs for which operational data is available have been negligible.
In 1989, however, it became necessary to renew 180 tones of steel in the ballast tanks of the tanker-based floating production storage and offloading facility FPSO II, offshore Palawan in the Philippines. FPSO II is a 127,000 DWT tanker permanently moored at the stern to a catenary anchor leg mooring system. This paper will explain why these renewals were required and how they were safely executed to the satisfaction of the Classification Society and Underwriters without interrupting oil production and export.

HISTORY
FPSO II was a normal trading tanker before her conversion to an FPSO in 1981. Built in 1968, she had one pair of segregated water ballast tanks (3 port and starboard wing tanks) in addition to the fore and aft peak tanks. During her conversion 4 port and starboard wing tanks were converted from oil service to ballast service - see Figure 1. At the same time the deck head structure within all these tanks was coated with coal tar epoxy from the tank top downwards for a distance of 2.4 meters. New anodes were fitted to the bottoms of all cargo and ballast tanks and up to a height of 9.6 meters from the bottom of all ballast tanks.
4 tones of steel were renewed in 3 port and starboard wing tanks in 1984. Additional anodes were fitted on completion of the steel repairs. In the second quarter of 1986, renewal of wasted anodes was carried out in 4 port and starboard ballast tanks and 5 port and starboard slop tanks.
In late 1987 it became evident that major steel renewals would be required in 4 port and starboard wing tanks and in the forepeak tank. These renewals were concentrated in a band 8 m - 18 m above the tank bottoms (moulded depth is 22 m) - see Figure 2. This area is above the fitted anode level, and is about the level at which the ballast water is normally maintained on FPSO II. In a trading tanker the ballast tanks are generally kept either full or empty, but in an FPSO which loads crude oil continuously, the weight distribution is constantly changing. Operational experience has shown that to maintain the ships bending moments, shear forces and trim within an acceptable range it is generally best to keep the ballast tanks only partially full.
Structural Integrity and Design of Tandem Hull Floating Production Platform
Authors: Brown D.T. , Hogan B. , Witz J.A. , Patel M.H. 
Published: October 2008

Abstract:
The need for low cost floating platforms for well testing and oil production is not always being adequately met by either new-build semi submersible or ship shape hull forms. The tandem hull platform provides a potential solution. This paper presents methods for design and assessment of the structural integrity of a 'tandem hull' floating production facility. Such vessels consist of a surface piercing hull separated by a small distance from a fully submerged hull directly below it. The gap between the hulls is essentially open with the hulls connected together by short vertical bracing members.
The results presented in this paper are based on a generic tandem hull configuration. It is shown that the vessel has adequate structural integrity, but design of some critical areas of the vessel, particularly in the region of the inter-hull columns, must allow for the high dynamic loads which are a feature of the concept.

1. INTRODUCTION
The tandem hull platform can be regarded as a hybrid of monohull and semi submersible hull shapes. The vessel takes the form of a water surface piercing hull separated by a small distance (typically 4.0 m) from a fully submerged hull directly below it. The gap between the hulls is substantially open with the hulls connected together by short vertical bracing members of rectangular cross-section. Figure 1 shows a perspective view of a typical tandem hull design. The vessel hulls are of the order of 170 m in length with a beam of approximately 38 m. The vessel can carry in the region of 40,000 metric tones of oil storage in the lower hull.
The three major performance requirements for a floating production platform are high load payload capacity for process plant and oil storage, low motion response to waves and low construction cost. Both semi submersibles and monohull vessels have shortcomings when viewed against these criteria.
The tandem hull platform, however, combines the beneficial design features of both conventional monohull vessels and semi submersibles to satisfy the needs of both high payload capacity and low wave induced motion characteristics.
However, the emergence of these special purpose hull configurations requires a unified technical approach to such designs - both to place them within the context of other marine vehicles and also to enable better understanding of their hydrodynamic and structural behavior. This paper presents this approach for the tandem hull form in a floating production platform application where deck payload capacity and low wave induced motions of the stationary vessel are the primary design goals.
The paper presents the overall hydrostatic and hydrodynamic characteristics of the vessel, together with an investigation of its structural integrity and strength. Recommendations for further analysis are also provided.