bluuebunny/crossref_metadata_2025_split huggingface dataset:
The World's Largest Single Point Mooring Terminals: Design And Construction Of The SALM System For 750,000 DWT Tankers
Authors: Gruy R.H. , Kiely W.L. 
Published: October 2008

ABSTRACT
This paper will discuss the design, fabrication and installation of two (2) identical Single Anchor Leg Mooring (SALM) Terminals which serve as crude oil export terminals. Both are designed to safely moor and load tankers as large as 750,000 DWT in environmental conditions that will be occasionally severe.
The determination of mooring forces via calculation and model tests and the design and fabrication of the components which transfer these loads will be discussed. Of particular interest is the design and fabrication of the "heart" of the systems, the fluid swivel assemblies which include several innovative features with respect to operation and maintenance. These fluid swivels are the largest ever built for SPM applications and are designed to transfer crude oil and bunker fuel oil simultaneously and to absolutely preclude the possibility of commingling of the two fluids. Model tests that were conducted on the fluid swivel/loading hose system will be discussed.
The foundation design and the optimization of this design with respect to available offshore construction equipment will be outlined as will the installation methods employed.

INTRODUCTION
The safe, efficient and economical transportation of crude oil from typically remote producing areas to the consuming areas of the World presents several difficult problems. Solutions to any of these problems offer attractive cost savings for crude oil feed stocks.
A major step in optimizing crude oil transportation has been the development of the Very Large Crude Carrier (VLCC). Unfortunately, the development of the VLCC has threatened to outpace the development of terminals suitable for loading/unloading these giant, deep draft vessels. One solution to this problem that has gained wide acceptance in recent years is the Single Point Mooring (SPM) or "monobuoy" type of terminal.
The SPM terminal solves several problems that are inherent to other types of tanker loading/unloading facilities (harbors, jetties, sea islands, multiple buoys and fixed towers):It can be readily placed far offshore in the deep water necessary to accommodate deep draft tankers.It can operate efficiently in rough seas and is not sensitive to directional changes of wind, waves and currents. With the tanker moored via bow lines only to a single buoy, the tanker is free to "weathervane" about the buoy and stay head-on to the weather, thus reducing mooring forces and increasing terminal utilization.It reduces operational dependency on support vessels such as tugs.It is generally less expensive to construct and/or operate than the other types of loading/unloading facilities.
This paper describes the ARAMCO - Ju' Aymah SALM Terminals (Arabian Gulf) which are the largest export SPMs ever built, and discusses the unique design features that were incorporated into these systems to make them safer, more efficient and more economical to operate than previous SPM designs.
Interpretive Methods Of Stratigraphic Modeling
Authors: Frink Alan P. , Wittick Thomas R. , Dedman Emery V. 
Published: October 2008

ABSTRACT
The technique described is of utmost importance in stratigraphic interpretation because it measures sonic velocities and densities and their lateral variations. It will work on layers as thin as 40 feet. These changes can be indicative of facies changes or changes in lithology. The relative amplitudes and stacking velocities of seismic data comprise the required input to the method, however, if sonic and density logs from the area are available, this information" can be incorporated leading to greater control of the final results. The procedure requires that the shape of the propagating wavelet in the data be known and that it be a symmetric, zero-phase wavelet.
The method is automated, and the end product is velocity and density information for a stacked seismic trace which is displayed similar to velocity and density logs. An iterative scheme minimizes the differences between the response of a seismic modeling system and the seismic data, based on matching amplitude ratios of the data. The method can be performed on as many stacked traces in an area as is necessary to achieve the objective of the explorationist.
The technique has been applied to marine data from several different geologic provinces. When the results were compared to. sonic and density logs in the proximity of the seismic data, the correlations were good.

INTRODUCTION
In order to effectively use seismic data to define and evaluate potential stratigraphic traps, we must be able to detect lateral changes in velocity or some lithology-related physical parameter such as acoustic impedance. We will demonstrate two modeling methods which use the amplitude information in the data to transform seismic data into velocity or acoustic impedance logs.
A related problem concerns the correlation of seismic data and well log information. The sonic and density logs give detailed information at the well which can be correlated to lithology; however, they can only measure velocity and density at the borehole. Conversely, seismic data, while lacking in the detail possessed by log data, can be used to detect and measure lateral variations in velocity. We will show methods which make seismic and well log data more correlative. We will further develop techniques for using the detailed velocity information available at the well to calibrate the logs derived from seismic data. These logs will then be used to measure velocities and their lateral variations away from the well.

GENERAL SEISMIC PROCESS
Figure 1 is a schematic representation of the seismic process and the role of the interpreter. In the center of the figure is a seismic trace which is the result of collecting seismic data over the subsurface depicted on the left of the figure. This operation can be expressed in terms of simple communications theory as the convolution of the earth reflection series with a propagating wavelet.
Rough Weather Drilling Vessel Simulation
Authors: Shell R.C. , Masso A.H. 
Published: October 2008

ABSTRACT
The Gulf of Alaska may have the roughest wave climate ever faced by the offshore oil industry. The high cost of time lost due to these rough seas was a major factor in selecting a floating drilling rig. This paper describes a simulation method that was used to estimate down times of floating rigs in the Gulf of Alaska and can be applied to other roughweather areas.
The simulator has two parts: one that simulates operations and another that simulates weather interference with those operations. While the operations model "drills a well," a novel weather model generates both wave heights and periods. Wave heights and periods determine vessel motions, which are checked against operating limits. If motions exceed the limits, work is "slowed down" or "stopped." By "drilling" - simulating - a large number of wells, reliable statistics on the down time of a particular rig are developed.
The weather model in the simulator can be applied to other offshore areas provided enough wave data exist. This approach also can be used for simulating offshore tanker loading, pipelaying or platform installations. Furthermore, the simulator can assess the value of hardware improvements that permit operations to continue in rougher seas. Statistical tests on the weather model showed that it adequately simulated Gulf of Alaska sea conditions. Furthermore, rig down time calculated with the simulator proved to be more realistic than down times calculated with models using just wave height.

INTRODUCTION
While waiting for rough weather to subside, a floating drilling rig will still cost up to $100,000 per day even though no work is being accomplished. Down time is expensive. And weather down time is even more important in selecting rigs for rough weather areas. Minimizing this expense can be done best by selecting an optimum rig design, one with the least down time under given sea conditions. This is not an easy task, given the many different rig designs proposed for rough-weather areas like the Gulf of Alaska. This task was simplified by a drilling vessel simulator that calculates down time and pinpoints operations particularly sensitive to weather-caused interruptions.
The simulator used two interacting parts: one that simulates offshore drilling operations, and another that simulates weather interference with the operations. While the operational model "drills" a well, the weather model generates wave heights and periods. The wave heights and periods determine vessel motions that are checked against operating limits. If the motions exceed the limit, work is "slowed down" or stopped. By drilling many wells, the simulator develops reliable and relistic downtime statistics.
The novel weather model simulates both wave height and period, whereas previous weather simulators generate only wave height. This model also can be expanded to include additional parameters such as current and wind speeds. This advanced weather model was needed because motions of drilling vessels depend on both wave height and period.
Lateral·stability Of Submarine Pipelines
Authors: Karal Karel 
Published: October 2008

ABSTRACT
The upper bound approach of the theory of perfect plasticity has been applied to develop a method for geotechnical stability analysis of unburied submarine pipelines. The coefficient of? lateral resistance of the soil and the corresponding displacements of the pipe depend on seven geometrical, loading and material parameters. Compared to the comfits based on Coulomb friction, the coefficients obtained by the present method are, in general, higher for pipes on sand and lower for pipes on clay.

INTRODUCTION
The complex problem of the interaction between water, pipe and soil for an unburied submarine pipeline is traditionally separated into two parts:the determination of wave and current action on the pipe in the form of lift, drag and inertia forces (in this paper termed as hydrokinetic forces); andthe investigation of lateral stability of the pipe exposed to known hydrodynamic forces.
Lateral stability is often the critical factor for determining the necessary weight of pipe coating, especially in Shallow waters (?100 - 120 m).
Appreciable attention has been devoted to the solution of part (a) of the problem,' including the pertinent gathering of environmental data and experimental results. If this effort is to gain the intended meaning, attention must be paid also to part (b) of the problem - transmission of the hydrodynamic forces into the soil.
This paper describes a method for-predicting the lateral soil resistance to a pipe. The method employs a limit analysis by upper bound technique 1, 2,3 afforded by the theory of perfect plasticity.

AVAILABLE METHODS OF ANALYSIS
The lateral resistance of soil to a submarine pipeline is commonly treated as Coulomb sliding friction, the lateral soil resistance Rl being written as:
(Mathematical equation available in full paper)
where f = friction coefficient and Wn net Submerged weight of the pipe defined as:
(Mathematical equation available in full paper)
Here Ws submerged weight of the pipe, and Pv = vertical component of hydrodynamic forces, taken as positive upwards
This approach is based on the assumptions that:the support is rigid,the pipe is sliding parallel to the surface of the support, andRl is independent of lateral displacement
These assumptions fail for most actual physical problems. The soil is not rigid, the sliding does not develop along the soil surface, and the soil resistance depends on the displacements of the pipe. Thus it should be expected that this approach will fail for the most actual loading - soil - pipe conditions. Reliable results, however, can be obtained for "light" pipelines supported by dense sand using the approach based on Coulomb friction.
Lyons7 has concluded that "Coulomb friction is not valid for lateral sliding on soft clay". For this case he has presented some results derived by a finite element procedure. These results alone, however, are not sufficient for determination of lateral resistance of pipes with other geometrical, loading and soil parameters.
Behavior Of The Bouchard #65 Oil Spill In The Ice-Covered Waters Of Buzzards Bay
Authors: Deslauriers Paul C. , Martin Seelye C. 
Published: October 2008

ABSTRACT
Most of the present data on oil pollution in ice-covered waters has been obtained from spills in static ice conditions. Thus, the Buzzards Bay spill, which occurred in moving ice, was of particular interest. Initially, the strong tidal currents transported most of the oil leaking from the barge into the broken ice field and beneath the large ice floes. The oil then collected in the crack systems of the rafted ice, hummocks, pressure ridges, and leads, and occupied an area of about 0.1 sq km. Oil pools formed by the rafted ice contained up to 2,000 gal of pure oil. No. 2 oil that was incorporated in hummocks and ridges was not as concentrated. Some oil in concentrated areas spread onto the ice floe surface primarily by wind forces. The No. 2 oil weathered at different rates, ranging from 6 to 47 percent volume loss, depending upon ti1e degree of oil exposed to the air. On Feb. 5, 0.1 m of snow fell at Buzzards Bay covering most of the oil from view; oil in concentrated pools formed a slush-like mixture containing 30 percent oil by volume. This snow greatly hindered aerial surveillance, research efforts, and cleanup attempts. Several cleanup techniques were used; the most successful was direct suction from concentrated pools into vacuum trucks accounting for nearly 13,000 gal of recovered oil. The ice began to break up around Feb. 8, releasing the oil contained in the ice in the form of a thin sheen. In addition, oily ice floes were transported by the currents through Cape Cod Canal into Cape Cod Bay, where they melted. These processes continued until about Feb. 26, 1977, when Buzzards Bay was essentially free "of visible oil.

INTRODUCTION
Buzzards Bay, located on the Massachusetts Coast, is a shallow, nonestuarine bay, approximately 46 km long and 19 km wide, with an average depth of 11 m. Connecting Buzzards Bay with Cape Cod Bay to the north is the manmade Cape Cod Canal (Fig. 1). The winter of 1977 was unusually severe for most of the northeastern United States with unusual icing conditions reported for many parts of the New England coast from December through February. Buzzards Bay, which normally does not ice over, was 90 percent covered by Jan. 28.
The ice that formed was less saline than normal sea ice because the waters in northern Buzzards Bay are slightly less saline than the waters found in Cape Code Bay and the southern portion of Buzzards Bay. Also, during the month preceding the spill, the Buzzards Bay ice had gone through four periods of above-freezing temperatures and rain that lowered the salt content of the ice. This low-saline ice was not as porous or elastic as normal first-year sea ice.
Several types of sea-ice formations were found in Buzzards Bay. Shorefast ice, with a characteristic thickness of 0.3 m, covered the waters of the protected coves.
Foundation Design For Gravity Structures With Respect To Failure In Cyclic Loading
Authors: Foss Ivar , Dahlberg R. , Kvalstad T. 
Published: October 2008

ABSTRACT
The behaviour of soils during cyclic loading is examined, and it is concluded that "Failure in cyclic loading" has to be considered as a separate failure mode for foundations of offshore gravity structures. This failure mode is discussed and distinguished from "Quasi-static stability failure" which is the other important failure mode in the ultimate limit state. Rational safety criteria for failure in cyclic loading, which are not explicitly given in any of the current regulations for offshore structures, are developed in the terminology of the limit state method. A number of practical problems in the analysis of this failure mode are discussed, such as: the effects of random loading, application of the spectral analysis method, the effect of storm duration, the effects of non-uniform soil conditions ox stress distributions, principles for improvement of foundation safety. The paper concludes that failure in cyclic loading is the critical failure mode for several cases of practical importance. Only simple cases may be analysed accurately within the present state-of-the-art, and further development of theoretical methods is encouraged. Centrifuge model tests are useful for investigation of more complicated failure modes.

1. INTRODUCTION
The effects of cyclic loading is one of the most important considerations in the design of foundations for offshore structures, notably gravity platforms. Such effects influence the safety of the foundations against ultimate failure as well as platform motions in storm and long-term effects such as settlements and horizontal displacements.
The purpose of the present paper is to propose a design procedure which introduces rational safety considerations for dynamically loaded foundations of gravity structures. The principles of the procedure are equally relevant for all types of soil, but in the paper examples are limited to clay soils.
The procedure is based on the limit state method. According to this method the criterion for an acceptable design is that design capacity ? design loading effect.
The design capacity is an expression for the strength of the structure (or the foundation) where the safety requirement is introduced through reduction of the strength by a materials factor ?m. Similarly, the design loading effects are based on loads increased by a load coefficienty?f. The formal requirement to safety is thus introduced through two partial safety factors. ?m shall mainly account for uncertainties related to the strength of the materials, whereas ?f shall account for uncertainties related to the loading effects.
The safety criterion is checked for several limit states. Total collapse or large inelastic deformations which may have similar consequence as a total failure are analysed in the ultimate limit state. Other limit states may consider serviceability requirements (deformations, durability, etc.), long-term effects (fatigue), or the risk of progressive collapse. In the following we shall concentrate on the ultimate limit state.
Field Test Of Aguyed Tower
Authors: Finn Lyle D. , Young Kenneth E. 
Published: October 2008

ABSTRACT
A test guyed tower structure has been installed and maintained in 293 ft of water in the Gulf of Mexico. The experimental objectives, structural design, and tower construction are described in this paper. The test data presented illustrate that the wave induced dynamic response of the tower can be accurately simulated and that the spud can foundation performs satisfactorily. The field test results provide further confirmation that the guyed tower is technically feasible and a practical structure to serve as an offshore drilling and production platform.

INTRODUCTION
The guyed tower is a bottom founded offshore platform concept which differs in two major ways from a steel jacket platform. First, in contrast to a conventional jacket platform which uses pilings to transmit both the wave and gravity loads to the soil, the guyed tower uses a guyline and clump weight system to dissipate the wave energy and a spud can foundation to transfer the gravity loads to the soil. Second, since the sway period of the guyed tower is greater than the design wave period, the principal structure inertial forces always oppose the principal wave forces instead of adding to the total load as occurs on a conventional platform. Because of these two advantages the concept offers an economically attractive alternative to conventional platforms in water depths from 600 to at least 2000 ft (1).
In order to advance the development of the guyed tower, a one-fifth scale test structure was installed in the Gulf of Mexico during October of 1975 (2). Measurements of the structure's response to environmental forces corresponding to design level conditions were recorded and subsequently analyzed. This paper describes the main features of the design, fabrication, and installation of the test structure and presents highlights from the data obtained.

TEST OBJECTIVES
The main objectives of the test were to obtain data and information about the installation, dynamic response, guying system behavior, and spud can (foundation) behavior of a guyed tower structure in an actual offshore environment. The installation procedures that were tested included towing of the structure to location, upending, and setting on bottom by adding preload ballast to the spud can as well as deploying the guy lines, clump weights, and anchors, and tensioning the guylines to insure proper setting of the anchors.
The dynamic response of a guyed tower is more difficult to predict compared to fixed-bottom platforms because the tower motions are of sufficient magnitude to require consideration of the interaction between the structure velocity and the wave particle velocity. Further, preliminary analytical and model studies indicated that the response of the tower to waves is phased such that the principal inertial forces always oppose the principal wave forces. Thus the field test data served to substantiate the predicted dynamic response of the tower when subjected to actual ocean waves, wind, and current.