bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differences In Shear Strength Between Jumbo Piston Core and Conventional Rotary Core Samples
Authors: Wong Patrick C. , Taylor Brian , Audibert Jean 
Published: October 2008

Abstract
In order to reduce costs associated with offshore site investigations, particularly in deep waters, large-diameter piston corers (also called jumbo piston corers) have been used as a cost-efficient tool to supplement conventional drilling and sampling and to obtain continuous seafloor samples as long as 30m. The STACORÒ is believed to be the jumbo piston corer that has the least soil sample disturbance, due to its unique design. There have been indications that samples obtained using the STACORÒ piston coring system yield undrained shear strengths higher than those obtained using conventional rotary borings. For example, comparison of data from five sites offshore West Africa shows that undrained shear strengths measured with the minivane and unconsolidated-undrained (UU) triaxial test tend to be 19% higher in STACORÒ samples than in rotary boring samples. This paper explores the reasons for those differences and attempts to quantify the differences in undrained shear strength of samples obtained with the two methods. The higher strengths associated with the STACORÒ samples appear to arise from two causes. Firstly, comparison of water content profiles appears to show that the STACORÒ " blows by?? (by-passes) the upper 1.5 to 2m of the sediment column, most likely due to penetration of the STACORÒ base into the very soft seafloor soils encountered in deep waters. This depth shift results in an " apparent increase?? of the STACORÒ undrained shear strength profile of 2-3 kPa. Secondly, comparison of minivane and UU triaxial tests on STACORÒ samples and rotary boring samples shows that, on average, STACORÒ samples are less disturbed and, therefore, yield higher shear strengths. Design implications are discussed, suggestions to measure penetration of the STACORÒ base are offered, and the need for alternative characterization of the first 2 to 3m below the mudline is described.

Introduction
For planned production facilities in deep water where the soils consist of soft silts and clays, the use of large diameter piston coring systems offers advantages over conventional rotary borings. These " jumbo corers?? can be rapidly deployed and recovered, obtain a large volume of continuous sample material, and the sample material tends to be of high quality. They are, however, limited in their depth of penetration. For example, the barrel length on Fugro's STACORÒ system limits recoveries to 24m, as further described below.
The Stationary Piston Corer STACOR®
Development History. Large-diameter piston corers capable of sampling up to 30m of soft sediments have been derived from the well-known Kullenberg corer widely used for oceanography purposes, in theoretically unlimited water depth. However, the degree of soil remolding during the piston sampling process is unacceptable for geotechnical engineering purposes (Borel et al., 2002).
Geotechnical Sampling and Survey of Salt Strata
Authors: Stevens Ross , Frazer Andy , Richards Mark , Stacey Andrew 
Published: October 2008

Abstract
FSCL has just completed an exploratory borehole to determine the suitability of ground conditions for the development of the world's first offshore salt cavern gas storage scheme. The facility, for a UK developer, is a series of sub-surface caverns, to be created in the salt strata below the Irish Sea and when built (subject to planning consent and financing), will substantially improve the security of energy supply for the UK and Irish Markets. The paper will review the detailed planning, project risks and bespoke equipment that was needed to produce excellent, 100 mm diameter core recovery down to 865 meters below the seabed.
Site investigations to circa 1000 meters below the seabed are possible and cost effective solutions can be offered against the need for oilfield drill rigs. Excellent core recovery can be achieved in salt strata and can be combined with a detailed testing programme to give a total picture of the strata investigated. This may open the door to development of future offshore salt cavern facilities.
The return of 100mm core for the full depth of the borehole allowed direct correlation of the site with other land based salt strata core samples. The core samples correlated well with the downhole testing programme data and the result provided detailed characterisation of the geology investigated. The site investigation has provided the necessary information to design the salt storage caverns and moved the project forward from a possibility to a reality. The design of the gas storage caverns has commenced and the cavern construction programme is planned to start in 2010.
The caverns will provide an initial working gas capacity of 1,200 million cubic meters, and the storage facility will substantially improve the security of energy supplies for the UK and Irish markets.

Introduction
In August 2007 FSCL undertook an exploration borehole for Gateway Storage Company Limited (" Gateway??) in the Morecombe Bay area of the Irish Sea. The purpose of the borehole was to establish the feasibility of using the underlying salt beds as an area for gas storage in solution mined caverns. This was only the second offshore site considered worldwide. The British Government has set the highest priority on increasing gas storage capability in the United Kingdom.
Augmentation of a Mooring System Through Dynamic Positioning
Authors: Sargent J.S. , Morgan M.J. 
Published: October 2008

ABSTRACT
A dynamic-positioning (DP) system can be designed to stabilize and damp the motions of a vessel when moored as well as unmoored. The vessel motion dynamic characteristics are generally significantly different when the vessel is moored as opposed to unmoored and may Vary over a wide range with changes in depth, scope, pretension, mooring pattern, and offset. In the paper, a design process is described whereby the DP controller parameters and their fictionalizations are derived for smooth stable response through the operating regime of the moored vessel. Field results from a North Sea operating drill ship are compared with predicted results, and the problems that were encountered are discussed. An augmentation scheme is presented by which the DP system will automatically back up and reinforce the holding capability of the mooring system under varying weather conditions and yet remain quiescent in calm weather.
A mooring system may be deployed to extend the holding capability of a dynamically-positioned offshore drilling rig in shallow and intermediate water depths when heavy seas are predicted and vice versa. When the DP system is augmenting the mooring system, the DP system improves the damping of the moored ship in addition to increasing its holding capability, and minimizes the time required to deploy and adjust the anchor system by keeping station. For the worldwide operating offshore drilling or pipe laying rig, the combined DP and mooring systems offer unmatched flexibility and redundancy by extending the operating water depth of the rig yet providing low power requirements and operating costs in shallow water.

INTRODUCTION
Considerable discussion has been given to both mooring and dynamic positioning (DP) systems for offshore floating vessels.l, 2,3,4 However, generally speaking, in each case the discussions were limited to one system or the other at a time. This paper considers the combination of the two systems on one vessel and the manner in which the DP system can assist the mooring system.
The paper begins with a brief review of the sizing and dynamic characteristics of a mooring system. This review establishes the range of mooring system parameters which must be accounted for in the design of the DP system for effective assistance to the mooring system. Then, a design process for the DP controller is given which allows the DP system to effectively augment the mooring system in a stable fashion in all operating regimes of the mooring system.
Throughout these discussions, actual data recorded on the drill ship SAIPEM Due is used to amplify points of interest and connect theoretical with actual results. The data was collected off the coast of Italy in February 1973 and in the North Sea in Norwegian waters in May 1973. A description of the SAIPEM Due and its dynamic positioning and mooring system is given in Table I.
Before reaching the final conclusions, the paper contains a section describing less obvious benefits in using the DP system with a mooring system.
Mooring System for Atlantic Generating Station
Authors: Harlow E.H. , Harris Frederic R. , Kehnemuyi Muzaffer H. 
Published: October 2008

Public Service Electric and Gas Company of New Jersey Central Power and Light and Atlantic City Electric Company in joint ownership will construct the world's first major commercial floating nuclear generating station at a location approximately 3 miles east of Little Egg Inlet on the coast of New Jersey. The floating nuclear plant named Atlantic Generating Station, will consist of two units each capable of producing 1150 MW electric net and will be built by Offshore Power Systems at Jacksonville, Florida. (Figure 1)
Each unit of plant will be constructed on a steel barge hull measuring 378 feet by 400 feet in area and having a displacement of 160,000 tons. The units will be moored within a breakwater enclosure to minimize the environmental effects of the ocean on the plants. Since the two stations will be operated in all but the most severe weather conditions over a period of forty years the mooring system must restrain their motion to tolerable limits against forces hitherto unprecedented in designing vessel moorings. Figure 2 shows the site and layout.
There are several alternative concepts for holding the rectangular platform hulls in position during the storms, tornadoes and earthquakes that a nuclear plant must be designed to withstand during its life span.The most conventional method is by means of cables, ropes or chains - members that exert horizontal forces against the vessels but allow vertical motion with the tide, as in the age-old tradition of ship moorings. Note Jin Figure 3 that all chains are of equal length, thus equalizing tensile forces, and minimizing the rotational moment imparted to a plant by uneven resistance to a horizontal force.Another method is by vertical caissons, pylons or piles whose lower portions are embedded in the sea floor and whose upper portions rise close alongside the plant so as to resist horizontal movement by vertical cantilever action. (Figure 4).A variation of this is a more or less continuous pile-supported platform, surrounding the plant. (Figure 5).A different method is by horizontal struts, pivoted at each end, which transfer forces by axial tensile or compressive stress into dead men on two sides of the plant. (Figure 6).
Any of these methods must be capab1e of withstanding forces new to berthing floating bodies -- not so much because of the size of these vessels, for many modern tankers are larger, but rather because of the severe weather conditions that must be postulated, and the safeguards necessary for the preservation of the health and safety of the public, as required for all nuclear facilities. Even during hurricanes and tornadoes these plants must be maintained in position. Ships at moorings ordinarily leave port under such conditions, and their moorings are not designed for these unlikely extremes. Two levels of security are set -- one for safe operation of the plant, and the other for safe shutdown condition. Operation must continue in storms up to the severity of a 100year hurricane, and during earthquakes of moderate intensity.
Environmental studies for Major Offshore Developments
Authors: Heckard John M. , Woodford Donald L. 
Published: October 2008

ABSTRACT
Major offshore developments initiated or planned in recent years to ease the energy crisis include mono-buoys and docking islands for VLCCs and offshore nuclear power plants. Legislative requirements for environmental studies needed for licensing of such facilities is discussed as well as the scope of work needed for comprehensive environmental evaluations. Emphasis is placed on special considerations such as oil and LNG spill?s and movements, and dredging. Experience gained in ongoing studies will be of importance in planning similar projects.

INTRODUCTION
History teachers of the 21st Centurymay refer to the 1970's as a time when the United States was rocked simultaneously by an environmental crisis and an energy crisis. Future students may never appreciate the problems which the government and energy producing industries had to solve during an extremely short period of time. This paper will attempt to focus on one small aspect of that crisis period; namely, the environmental issue as related to offshore developments of the energy-producing industries.
The clash of our fuel "shortage" coupled with an increased concern for environmental protection has resulted in an interesting development. The energy related companies, particularly the power and petroleum industries, have turned their attention to the offshore in an attempt to mitigate the energy shortage. The petroleum industry, long involved in offshore developments, is entering a new era of SNG terminals, transportation of and dockage facilities for LNG, and deepwater ports for supertankers. Exploration and drilling are moving into virgin and deeper waters. Utilities and their vendors are designing offshore power plants.
Interestingly, this movement to major offshore developments is not necessarily consistent with environmental objectives. Outside of the arctic region, our most ecologically sensitive zones occur in coastal areas. Consequently, -improper construction practices or operational accidents can severely affect a valuable ecosystem. The Santa Barbara oil release incident demonstrated that, if designed and handled improperly offshore developments can aggravate environmental degradation, not arrest it.
The objective of this paper is to address environmental conservation in light of new and major offshore developments. We now have an experience record of two years and, while incomplete, it allows us to draw preliminary conclusions relative to federal requirements, the scope and depth of Environmental Impact Reports, the methodology for assessing environmental impact, and the application of earlier studies to new proposals.
Discontinuity Stress Decay in Offshore Platform Joints
Authors: Blackstone W.R. , DeHart R.C. , Maison J.R. 
Published: October 2008

ABSTRACT
The literature contains little useful design information on discontinuity stress decay in cylindrical shells near intersecting axial plate or tubular members. A widely used rule -of-thumb is that the stress will become regular at about one and one -half to two cylinder diameters from the discontinuity, but neither the validity nor the range of application of this rule has been established. This study uses the computerized finite element technique to define the decay rate and pattern in a cylinder near an insert plate, and in a cylinder near the intersection of a small branch. Additionally, the feasibility of using ring stiffeners for stress redistribution near the cylinder intersection is explored.

INTRODUCTION
Today-'s fixed and semi submersible offshore drilling platforms are being designed for use in deeper water and stormier conditions than their forebears. As tubular member diameters and thicknesses are increased to withstand more severe loads, structural weight optimization becomes a necessity. One region that is often overweight, and should therefore receive care- ful investigation, is the tubular joint. Also, as the platforms grow in cost along with size, both owners and insurers are requiring more accurate and comprehensive stress and fatigue analyses in assessing the reliability of the rig.
In recent years, the computerized finite element method has crone to the fore as a powerful and cost-effective numerical analysis technique for platform design in general and for tubular joint design in particular. (1) The soundness of the method has become widely accepted, and it has been used extensively in stress analyses of tubular joints in platforms currently under construction. Inmost of these analyses, the joint design and construction was already complete, including the reinforcements at anticipated critical stress regions; the finite element method was used primarily to validate the design and to locate areas where additional reinforcement was required, i. e., t'hot spots".
The above use of the finite element method is often the only alternative, sinceconstruction deadlines can force fabrication and stress analyses to proceed concurrently. There is a built-in inefficiency in this approach, however. One invariably finds regions of low stress in those designs wherein metal could be deleted without significant effect on strength. Unfortunately, such weight optimization is often uneconomical at an advanced stage of design and/or fabrication. Clearly, the finite element method must be implemented at an early design stage, e. g., before selection of reinforcements such as rings, gussets, and longitudinal stiffeners is complete, if weight is to be optimized. one current program at Southwest Research Institute (SwRI) involving components of a pipe lay barge pontoon.
Sedimentary Provinces, Lithologic Parameters And Direct Hydrocarbon Finding Technique
Authors: Zoerb Richard M. 
Published: October 2008

INTRODUCTION
Nothing in the past few years has so beguiled the exploration side of the petroleum industry a. she bright spot. The ultimate tool in oil finding, a direct means of identifying hydrocarbons, has been around as a dream for a long time, but in spite of much research has never really materialized in fact. Now, however, things may be changing. A particular blend of data acquisition techniques and advanced processing methods has given form to a remarkable new discipline in which bright spots and related seismic phenomena serve as interpretive leads, pointing to the occurrence of oil and gas in the subsurface.
It is perhaps significant that there is as yet little uniformity among geophysicists in matters of terminology or even in details of procedure and display. A strong consensus exists, however, in regard to directions research is going, and the goals such efforts should achieve. Study has thus far been concerned with seismic wave characteristics, principally amplitude, velocity and frequency. The end being sought is a means of positive detection of hydrocarbons at depth, in advance of the actual drilling stage in exploration.
While direct oil-finding techniques are of a distinctly geophysical nature, they can neither be ignored by the geologist nor discounted by him in his own efforts to find petroleum. The geologist's first concern may have to do with the universal applicability of the new methods. Are they as "direct" as their name implies? If "direct" is to mean avoidance of intermediate steps in exploration, then they plainly fall short of their mark. However, the methods have been given credit for improved success ratios in some areas, and this should be reason enough for further use on a much broader geographic scale than is the case today. Refinements also are a certainty, and should not only lead to higher levels of reliability, but permit adaptation to areas which at present are too problem-ridden to yield very acceptable results.
But the geologist's interests differ from those of the geophysicist since he is interested in where the techniques can be used rather than how or why they work. He must ask: Are direct hydrocarbon-finding methods, in the present or predictable state of their development, so impeccable an exploration tool that they can be used without challenge to their validity in any petroliferous province in the world? To find an answer it is necessary first to define a set of parameters wh1ch will dictate the viability of the technique, then test these limits against the geological qualities of differing areas of sediment occurrence.
A Review of Current European Research into the Effects of Offshore Mining on the Fisheries
Authors: Dickson Robert R. 
Published: October 2008

ABSTRACT
This paper describes the present status and expected growth of offshore sand and gravel dredging on the European Shelf, the effects on fisheries and a review of the adequacy of current research into these problems. In order to minimize conflicts of interest between the fishing industry and the rapidly expanding offshore mining industry, the paper advocates cooperative fisheries research into specified problems and recommends the establishment of a common European code of practice for dredging regulation.

INTRODUCTION
In view of the expansion of marine sand and gravel production throughout the European Shelf, the International Council for the Exploration of the Sea (ICES) has recently established a Working Group to identify the effects (direct and indirect) and international implications of different methods of marine sand and gravel extraction on the fisheries, to review techniques for studying these effects and to compare national codes of practice for the control of dredging activities. This working group of delegates from 11 member nations met at the Fisheries Laboratory Lowestoft on April 2-4, 1974, and its principal findings form the subject of this paper.

THE PRESENT AND PROJECTED STATUS OF EUROPEAN OFFSHORE MINING
In most European countries, the development of offshore sand and gravel extraction has been relatively slow, despite the expanding demand for material for concrete, roads and "fill" in engineering works. Until recently, land-based resources were adequate to provide an economical supply of both sand and gravel within a short distance of the major markets. However, as the pressure on land use for agriculture, housing and other environmental and social needs has become greater, extraction has been forced away from the vicinity of large towns; coupled with this, rising transport costs and increasing road congestion have caused a switch to marine sand and gravel production and have provided the impetus for rapid developments in marine mining technology. For example, Fig. 1 shows that, between 1960 and 1970, U.K. production of sand and gravel from marine sources increased from 4 to 13 million tons/a and the marine percentage of total production (land + sea) doubled to 12 percent.
Initially the dredgers were of small capacity; for example, as late as 1968, the average gross tonnage of British dredgers was 800 tons, but as Hill8 has pointed out, the average size of newly built British vessels in 1970-71 was 3,500 tons and vessels of up to10,000 tons are now in operation. These ships are now capable of working in water depths greater than 35 m and of unloading on a 24-hour cycle so as to make use of cheap tidal docking facilities. Where the industry requires the provision of a specified grade of material, the development of onboard methods of screening, separating and washing different size fractions has allowed the working of hitherto unsuitable or low-grade deposits.