bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Mooring Lines for Depths to 3000 Meters
Authors: Davies Peter , François Michel , Grosjean Francois , Baron Patrice , Salomon Karine , Trassoudaine Damien 
Published: October 2008

Abstract
This paper presents a study of the use of synthetic fibre mooring lines for deep-sea applications. Three materials are considered: polyester, aramid and HMPE. First, results from a test program completed recently are described. These tests on full size ropes, which include novel extensometric methods based on image analysis, have enabled the influence of mean load, load range and loading frequency on stiffness to be determined for the three materials. Ropes up to 750 tons MBL (minimum break load) have been tested. A comprehensive data set of this type has not been available previously. These data are then used in mooring system analyses, to evaluate a number of design cases for the station keeping of exploration and production platforms. This has allowed a better understanding of the domains of application of these different materials and of related issues for design. Materials research needs have also been clarified. The minimum tension criterion for HMPE and aramid fibre ropes is shown to be one of the critical technical parameters that should be further investigated in order to extend the further application of these materials for taut mooring systems design. Attention should also be given to fatigue analysis for the aramid and HMPE lines.

Introduction
As water depth increases, synthetic fibre ropes become increasingly attractive candidates for station keeping. In spite of some initial difficulties with aramid ropes 20 years ago1, over the last five years polyester has become an accepted alternative to steel for this application. The extensive studies and pioneering applications of Petrobras have led to increased confidence 2–4 and this is the preferred option for depths down to 1500 meters. However, with the numerous discoveries of large reserves in deeper water the question of whether polyester ropes can be used at all depths has been raised. Recently polyester was used in field trials down to 1900 meters depth5 but there are few guidelines concerning alternative materials. Chaplin & Del Vecchio compared polyester ropes to steel at depths of 500, 1000 and 2000 meters6. Cloos & Bosman compared nylon, polyester, and aramid ropes at depths to 3000 meters and concluded that there is a minimum depth for each material, that for aramid being 1000 meters7.
One aspect to be considered is the size and weight of large polyester ropes, and the implications for handling equipment and installation procedures. Figure 1 shows a comparison of rope sizes as a function of MBL (minimum break load). A 1000 ton MBL polyester rope has a diameter around 200 mm, and, with the several kilometer lengths to be deployed, this may exceed the storage capacity of anchor handling vessels. Figure 1 also shows that aramid and HMPE ropes are much closer to traditional steel wire in diameter. The equivalent polyester line will require two to three times the storage capacity that is needed for the other materials.
Economic Impact of Slimbore and Drill Through Xmas Trees on Deepwater Subsea Developments
Authors: Harrold David 
Published: October 2008

Abstract
This paper demonstrates cost savings that can be gained by selecting either slimbore or drill through Xmas Tree types to develop deepwater subsea fields. Field data and a computer model were used to quantify the CAPEX, OPEX and NPV life cycle cost savings these tree types can provide when compared to conventional vertical dual bore and horizontal Xmas Tree designs. The paper considers applications in depths from 2,000 to 10,000 feet.

Introduction
As operators embark upon development of deepwater subsea fields, long duration drilling, completion and workover cycles are encountered. The CAPEX and OPEX expended on these fields is largely governed by the cost to charter drilling rigs as opposed to the cost of the subsea hardware itself. However, the Xmas Tree type selected does have a major influence upon drilling, completion and workover durations and drilling rig selection. It is therefore imperative that the most suitable Xmas Tree is selected for any given application to minimize installation and workover durations whilst maximizing use of lower cost drilling and completion rigs.
Slimbore and drill through Xmas Trees were compared against standard fullbore vertical and horizontal Xmas Trees currently being installed in deep water. This paper is limited to comparing CAPEX and OPEX variances between the systems. Other technical merits or the relative risks associated with each system are not addressed or discussed. The ability of slimbore systems to utilize lower cost MSV vessels for installation and workover activities is examined and discussed. Time estimates and associated costs are presented for installation, tubing access workover, tubing retrieval workover, tree retrieval, well sidetrack and decompletion for each Xmas Tree. These costs were used to generate a financial model to compare the NPV life cycle costs associated with each system.
This paper is written assuming that readers have a fundamental understanding of subsea well completion operations and associated Xmas Tree hardware.

Xmas Tree Definitions
A brief description of each Xmas Tree type compared in this study is provided below. All Xmas Tree types are guidelineless (GLL) configurations, which are either currently in use or are being proposed for use in deep water field developments. The associated installation and intervention tools, which are used with each system, are also described. To the knowledge of the author, no subsea wells have been completed at water depths exceeding 7,500 feet and some technology development is ongoing to extend well completions to ultra deepwater. This fact will also impact Xmas Tree selection criteria, at least in the near term.

Conventional Dual Bore Vertical Tree (CXT).
The CXT is a dual bore configuration with an ROV installed, pressure containing tree cap. The tubing hanger is an 18-3/4" full bore design that is installed directly to the wellhead. The tubing hanger contains a hydraulically operated valve to provide annulus isolation.
An Earthquake/Wave Instrumentation System for Offshore Platforms
Authors: Titlow Joseph D. 
Published: October 2008

ABSTRACT
The dynamic response of offshore drilling platforms during earthquakes and heavy sea conditions becomes increasingly important as water depth increases. Predicting the structural response of a platform depends upon the characteristics of the excitation and the dynamic properties of the platform. Recorded data on the behavior of full scale structuresduring earthquakes and heavy sea conditions is scarce. However, analytical methods have been developed recently which can be used to silll1late the dynamic response of deep water platforms. This paper describes an experimental program whose major objectives are (a) collection of data describing the characteristics of earthquake and wave excitations and the resulting structural response and (b) validation of analytical methods for predicting the dynamic response of platforms.
The Earthquake/Wave Instrumentation System was designed and installed on Platform Hope off carpinteria, California. The system measures and records accelerations, wave height profiles, and the accelerations of the platform during these events. This paper describes the innovations in the system that were required to meet the concepts and objectives of the experimental program.
Early results from operation of the system are reported. This includes analysis of ambient vibration tests which yield data on the fundamental natural frequency of the platform. Wave data from a moderately large storm is reported.

Basic System Concepts
There are three basic concepts which led to the development of the Earthquake/Wave Instrumentation System:the need for design tools which would provide better estimates of the dynamic behavior of platforms during earthquakesand heavy sea conditions,the need for strong-motion instrumentation on an offshore platform to supplement the onshore network, andthe need to delay large data handling expenditures until the value of the data could be determined.
These concepts formed the guidelines for decisions on the eventual system design and hardware.

Dynamic Behavior of Platforms
Offshore platforms, whose heights are less than 300 feet, can usually be designed using static methods only. These platforms exhibit essentially static behavior, since their natural frequencies are sufficiently separated from the frequency band associated with high-density wave energy. Platforms can be economically designed in the 300 foot to 600 foot range that are relatively stiff and have adequate frequency separation. However, above 600 feet the lowest frequencies approach the frequency band of maximum wave energy. This implies the structure will exhibit dynamic behavior and that it should be designed using methods which considers its dynamic properties and response characteristics. All deep water platforms in areas of high earthquake activity should be designed using dynamic methods.
Design of Piled Breakwater Structure for New Port of Manfredonia,Italy
Authors: Toppler J.F. , Harris Frederic R. , Maaten R. 
Published: October 2008

ABSTRACT
This paper discusses the structural design of a breakwater ut1lizing steel bearing piles, concrete deck and concrete front wall.
To substantiate the design criteria, extensive model testing was performed with irregular waves simulating prototype wave energy spector. From the test it appeared that total forces over a limited length of breakwater, due to breaking waves, could be higher than those of the preliminary calculations based on theory. However, for a 100 meter long rigid "unit of breakwater, a reduction of at least 20% in the total forces due to spreading in time of local peak forces, was obtained from 3-dimensional tests. The influence of structural response was studied with the aid of an electronic analogue of the linear mass sprine system.
The model test showed that the configuration of the sea bottom, hence the width of scour protection affects the wave pressures on the breakwater. The experiments showed that this also holds for the overtopping rates, measured with two parapet shapes.
The resulting design showed that utilizing a batter pile type structure solution can be successfully employed as a breakwater construct ion in relatively deep water, where the conventional types of construction, due to the poor soils condition, would have been uneconomical.

INTRODUCTION
The township of Manfredonia is located on the Adriatic coast of Italy, north of Bari. '.the existing port of Manfredonia has very limited waterdepth. As a result of the new industrial expansion in the area, it was decided that the port facilities should be extended to be able to receive vessels up to 25,000 DWT carrying general cargo, bulk cargo and petroleum products. For ships of this size a minimum water depth of 11 m is required. Since the existing port could not be extended to accommodate these vessels due to the limited water depth available, the new port had to be located approximately 2 km offshore.
Due to the type of cargo to be handled, the port had to be protected from the seas. Detailed investigation of the sea and meteorological conditions was carried out to establish the extent of the protection required and the configuration of the new port. The requirements for initial throughputs dictated that the first phase of the development shallhave five berths. Allowance was made for construction of additional berths in the future.
In this paper no attempt was made to give a detailed account of the studies carried out and how the final configuration was established. A detailed description of the design -of the breakwater with special emphasis on the model testing, however., was presented.

GENERAL BACKGROUND
At the commencement of the preliminary engineering, since no information was available on the existing soils condition a, the study of the breakwater was concentrated on the use of conventional type of construction.
Towed Vehicle for Constant Depth and Bottom Contouring Operations
Authors: Conti Ugo , Wilde Pat , Richards Tommy L. 
Published: October 2008

ABSTRACT
A towed vehicle capable of constant depth operation and bottom contouring has been designed and built for'pol1uiion monitoring studies in estuarine and marine environments. The principal characteristics are:Length.... ........54 inchesWing Span .........39 inchesBody Diameter......9 inchesTowing Speed.......1-4knotsOperation Depth ... Surface to 100 feetOperating Modes ... Bottom Contouring Constant DepthBottom Contouring..10 to 30 feet above bottomWeight in Air......110 poundsBuoyancy.............6 poundTowing Cable Type...1/4 inch polypropylene ropeTowing Cable Length ... 100 - 300 feet
The basic configuration of the vehicle is that of an airplane with fixed forward wings and rear movable elevators. The elevators can assume two positions that correspond to (1) diving and (2) surfacing. The distance from the bottom is measured with an echo sounder and the depth with a pressure gage. The control system is of the, open loop type with a yes - no mode of operation. The most interesting characteristics found in the preliminary study and tests with a full size wooden model were that (1) the lift to drag ratio is relatively independent of the velocity for a constant elevator setting and (2) the response to a weaving force of 10 pounds with a period of × seconds is a displacement from the line of motion of approximately × feet.
Sea trials made in the San Francisco Bay showed that without automatic controls the vehicle reached a certain depth in about 20 seconds and maintained this depth within ± 6 inches. In the bottom contouring mode the vehicle followed the bottom with oscillations contained within 4 - 5 feet. In the constant depth mode, depth was maintained with oscillation contained within 5 - 5 feet.

INTRODUCTION
The most common systems used for gathering environmental data in marine waters can be grouped in two general cateogries.On station measurements or water sampling along the water column.Underway measurements using a submerged instrument housing or a submerged pump and inboard instrumentation.
Our particular problem was to measure a large number of environmental parameters in estuarine and coastal waters for pollution assessment. In this particular environment, because of the varying of the physical condition (currents, eddies, long shore drift, etc.) it is difficult to establish a clear picture of the distribution and concentration of pollutants unless a great amount of data is gathered in a relatively short time.
In designing an instrumentation system adequate for this problem, we also stressed low cost and simplicity of operation.
We chose to use a towed underwater vehicle housing the sensors, the data recording system and all the necessary power supplies, and capable of maintaining either a constant depth or a constant distance above the bottom, because a large number of continuously monitoring fixed stations is both very expensive and impractical in a marine environment.
The Influence Of Environment Condition On The Design Of Cathodic Protection Systems For Marine Structure
Authors: Davis Jack G. , Doremus G.L. , Graham F. Wayne 
Published: October 2008

ABSTRACT
Environmental conditions should and definitely do influence the design of cathodic protection systems for corrosion mitigation on marine structures in all areas of the world. Selection of components of the corrosion mitigation systems are influenced by environmental conditions from both an electrochemical and mechanical standpoint.
Corrosion rates on metals are influenced by their environments, and there is quite often a definite relationship between the corrosion rate and the protective current density required to prevent corrosion.
A cathodic protection system designed for an offshore platform or drilling rig in the Gulf of Mexico may not operate with the desired results in the North Sea area. A cathodic protection system designed for corrosion prevention on a structure in straight sea water would not perform satisfactorily for the same structure in brackish or polluted waters.
Environmental conditions should and definitely do have an influence on the corrosion rates of submerged steel and the design of cathodic protection systems for corrosion mitigation on marine structures. In orderfor a cathodic protection system to perform properly and thus prevent corrosion, the environment in which the system must operate must be taken into account as a primary consideration.
There are two general types of cathodic protection systems: galvanic anode systems, employing sacrificial aluminum, zinc or magnesium anodes; and impressed current systems, employing rectifiers and semi-inert anodes. The selection of the type of cathodic protection system depends largely on the environment and its overall effect on the structure to be protected and on the protective system.
The effects of environment will be handled in two broad classifications, electrochemical and mechanical, and they will both be related in this discussion to the natural sea water offshore in the Gulf of Mexico as an average or "norm" for environmental conditions. It is logical to select the Gulf as an average of environments since it contains more offshore platforms and other related marine facilities than any other body of water in the world. It follows that experience withcorrosion and cathodic protection on steel structures in the Gulf is very extensive.
For steel structures in natural sea water there is an approximate equality between the corrosion rate, expressed in mils per year (mpy) and the amount of cathodic protection current (direct current), expressed in milli per sq. ft. of submerged steel area, required to prevent corrosion. In Gulf of Mexico water the value is 5, i.e., the corrosion rate on a continuously submerged steel structure is approximately 5 mpy (.005 inches year) and the cathodic protection current density for attainment of a minimum protective to-water potential indicative of complete corrosion control is 5 milliamperes anodic per sq. ft. of submerged steel area.
Simulation of Contaminants in Bays - Application to San Francisco Bay Complex
Authors: Theodore Louis 
Published: October 2008

Abstract
This is the first in a projected series of papers concerned with the development of a mathematical model to simulate the behavior of' a contaminant in a series of' bays. Although this general problem traditionally falls within the domain of the sanitary engineer, chemical engineering principles and techniques were successfully applied in this research effort. The contaminant-bay system is represented by the conceptually similar combination of a reactant in a series of continuously stirred tank reactors (CSTR).
Specifically, the model incorporates forward feed as well as bidirectional interchange (backmixing), recycle, first-order reaction and independent auxiliary inputs to each reactor. Although the analysis is presented for three reactors, an extension to a larger system is easily accomplished.
Analytical solutions are obtained for diverse variable feed concentration. An analog computer approach is also included. In addition, a general digital computer program is developed which uses the Runge-Kutta numerical integration technique to solve the general set of equations dictated by the model under various conditions. System conditions include time variable flow rate, feed concentration and reactor volume, auxiliary inputs and reaction rates.
After appropriate representation of the required parameters, the model is applied to the San Francisco Bay complex, and the resultant equations are solved using the general digital program. Tidal effects are simulated by using bidirectional feed interchange. The calculated results predicted daily concentration profiles in qualitative agreement with what one would expect. The monthly concentration profiles generated compared favorably with existing experimental data.
The results of this study suggest that modelling techniques may prove a valuable and effective tool in simulating other water contaminated and air-polluted systems.

Introduction
The problem of water pollution has demanded increasing attention in recent years. The challenge of' treating water contaminated with industrial and municipal wastes and the associated problem of treating wastes before they are deposited in waterways has not eceived the same attention by the engineering profession as other technological problems. The sanitary engineer has been traditionally concerned with this subject. The chemical engineer, aided by his background and training in reaction kinetics, unit operations and transport processes, has also contributed to the solution of this problem in recent years. Some of the research effort by the chemical engineer has been directed to the general area of mathematically describing the concentration and flow pattern of contaminants in bodies of water.
The purpose of this study is to apply chemical engineering principles and techniques to obtain a mathematical model describing the concentration and flow behavior of contaminants in a series of bays.
Brazilian Petroleum Exploration and Production: From Monopoly to Free Market
Authors: de Luca João Carlos 
Published: October 2008

Abstract
Four important phases are identified in the evolution of the Oil industry in Brazil.First phase: from the beginning of the industry up to the creation of the National Petroleum Council (CNP), in 1938.2. Second phase: from 1938 to 1953. The activities, exclusively onshore, were carried out by CNP, until the creation of PETROBRAS and the concept of the state monopoly.Third phase: from 1953 to 1998. Great development of the industry, supported by the monopoly, held by PETROBRAS. This phase shows two great E&P cycles: an onshore cycle, from 1953 to 1968, and a predominantly offshore cycle. This cycle is marked by great challenges and technological achievements, with the exploration activities in the Campos Basin progressing into even deeper waters as a consequence of the successive discoveries of large fields and substantial increments in the proven reserves, which in this phase reached 9 billion barrels and the production of 1 million BOPD.Fourth (current) phase: Began with the publication of Law 9.478 in August 1997, which eased the monopoly, opening the market to competitiveness and created the National Petroleum Agency (ANP). The private investors answered immediately and, after 4 successful bidding rounds, 38 new concessionaries are active in the Brazilian sedimentary basins. As a result, it is expected the discovery of part of the 25 billion oil barrels potential to even out the R/P ratio, unbalanced by a vigorous production growth which now reaches 1,5 MMBOPD, on the way to the country's self-sufficiency by 2005. The evolution of the E&P segment in this new phase has the strong effect of increasing the local industry of goods & services with the local generation of value, employment and tax profit. Its economic importance may be gauged by its direct contribution to the Gross Domestic Product (GDP) growth.

Introduction
The first initiative to find petroleum in Brazil dates back to 1897, when the farmer/landowner Eugênio Ferreira Camargo, after observing an oil seep on an area where he had an old concession for the exploration of coal, drilled the first well in Bofete, state of São Paulo. The well was drilled to a depth of 488 meters and yielded but two barrels of oil. With such a result and the high costs, the activities were discontinued. In 1908, I.C. White, an American geologist contracted by the Brazilian Government to assess the hydrocarbon potential of the Southern states, presented an unfavorable diagnostic due to the abundance of igneous rock.
More serious endeavors on the part of Federal Government explore and produce petroleum in Brazil, in spite of little surface evidence of oil, ocurred as of the First World War (1914-18), with the creation of the Brazilian Geologic and Mineral Service (SGMB), of the Ministry of Agriculture.