bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Response of Surface-Moored Vertical Barrier to Wave Action By Analog and Digital Simulation
Authors: Fowler Joe R. , Bailey Edmond I. 
Published: October 2008

Abstract
The two dimensional dynamics of an oil containment barrier, which was designed to have very low tensile loads due to current and waves, were simulated with a theoretical model. The model was solved on both analog and digital computers, and a lab test program conducted to verify the model.
For nonlinear problems such as this, for which "exact" solutions do not exist, the analog computer has many advantages, principally rapid parameter studies and convenient plotting output, plus giving the engineer a real time "feel" for the problem. The problem treated here was especially well suited to analog simulation. Charts and graphs present maximum force and amplitude data, and experimental verification of the solution was obtained from wave tank studies.

Introduction
In 1970 researchers at Texas A&M undertook the task of designing a light weight mechanical barrier to contain oil spills at sea. Studies indicated that the failure of barriers available at that time was due to current and wave induced tensile loads which, if they did not cause the barrier to tear apart, at least made it impossible for the barrier to adequately follow the ocean surface and prevent oil leakage over or under the barrier.
A typical barrier two feet deep and 1000 feet long will have several thousand pounds tension in a 1-2 knot current. The ability of this barrier to respond to waves is analogous to that of a taut clothesline. Waves will induce structural loads in this barrier nearly as large as those which would be imposed on a fixed structure of the same size and shape. To circumvent these problems, the design depicted in Figure 1 was proposed.
The essential features of the barrier are:The barrier skirt, which is actually the oil retention portion of the barrier, is separated from a main tension line by bridle lines spaced about every two feet along the main tension line. This separation by many lines guarantees that the current or wave induced tension in the barrier skirt itself will be very small. The dual advantages of this low tension are: first, structural integrity is assured, since the only highly loaded portion of the system is the main tension line (a very efficient load carrying member), and secondly, the low tension allows the barrier to follow every profile and contour in the sea.The bridle lines are made of elastic shock cords which have the basic mechanics of a rubber band. They allow the barrier to follow with waves coming into the barrier, thus greatly reducing wave-induced forces. The reason for this is that since the relative velocity of the barrier with respect to the sea is much less than with a non-conforming system, the loads in the barrier, which are proportional to the square of this relative velocity are also much smaller.
For a configuration as shown in Figure 1, the tension in the barrier would be on the order of 10 pounds, rather than thousands of pounds.
Stainless Steels in Quiescent and Flowing Seawater: Effectiveness and Pitfalis Of Cathodic Protection
Authors: Groover R.E. , Lennox T.J. , Peterson M.H. 
Published: October 2008

Abstract
The corrosion characteristics of nine types of stainless steel were compared in quiescent and flowing seawater at Key West, Florida, both with and without catholic protection. The median electrochemical potentials of the freely corroding and catholically protected specimens and histograms for selected alloys are presented.
All unprotected specimens were severely corroded. Crevice corrosion was the predominant form of corrosion, but some alloys also pitted and corroded at the edges. An acid condition (pH 1.2 to 2.0) was measured in the solution in active crevices, and the ions of all the major alloying elements were identified in the solution by means of thin-layer chromatography.
Catholic protection by either mild steel or zinc galvanic anodes effectively reduced the corrosion on all alloys except for shallow pitting around and under the steel anodes. Blisters were noted on four alloys which were protected with zinc anodes. The solution pH in the crevices on the specimens protected with mild steel anodes ranged from 7.0 to 8.5, whereas the solution in the crevices on specimens protected with zinc anodes had a pH that ranged from 8.0 to 9.7. These pH values indicate that a benign environment has been formed within the crevices. The effectiveness of catholic protection in the crevices was also apparent from the negative chromatographic tests for ions of the constituent elements of the steels
Previous research by the Naval Research Laboratory had shown that 17-4 PH stainless steel, when heat treated to yield strengths greater than 160 ksi, had a markedly lower load-bearing capacity when catholically polarized to potential!: equivalent to that of a Zinc anode. The present study investigated the effect of catholic protection on the cracking behavior of lower yield strength (123.6 and 146.7 ksi) 17-4 PH stainless steel. A reduction in load-bearing capacity was also observed for the lower yield strength material.

Introduction
Because of the increased availability of ferrite stainless steels and the high cost of nickel, there has been an increased interest in stainless steel alloys which contain little or no nickel. The use of these alloys in seawater could lead to serious corrosion problems, because they have been reported to be highly susceptible to crevice corrosion when unprotected and subject to blistering (1) when catholically protected. Precipitation hardening alloys have been observed to crack (2,3,4) when catholically protected.
Drainage Piles -A Method for Increasing The Axial Capacity of Friction Piles
Authors: Kinra R.K. , Luque R.F. , van Daalen F. 
Published: October 2008

Abstract
This paper describes a method for increasing the axial capacity of friction piles embedded in clay soils. The proposed method consists of increasing the shear strength, and consequently the soil-pile adhesion, of the soil around a pile. This is accomplished by draining water from the surrounding soil into the pile. Equations are developed to predict the maximum pile capacity, and Terzaghi's theory of radial consolidation is used to predict the variation with time of the bearing capacity during the drainage process. Results from preliminary laboratory tests that demonstrate the feasibility of the drainage pile concept are described, and practical considerations that need to be investigated in greater detail are discussed.

Introduction
This paper introduces an unconventional method for increasing the load carrying capacity of offshore platform piles. The basic concept consists of increasing the axial capacity of friction piles embedded in clay soils by facilitating drainage of water from the soil formation into the pile. In this system, the drainage pile is analogous to a well point. The reduction in water content due to drainage causes the soil to consolidate around the pile, resulting in an increase in the soil shear strength. This leads to an increase in the soil-pile adhesion, and consequently in the axial pile capacity. The principle of driving water out of a soil layer in order to increase the soil strength locally is already a familiar one in the area of soil stabilization, and is the basis of sand drain technology and electro-osmosis.
The conventional method of increasing the axial capacity of friction piles is to increase their diameter or embedded length. The pile dimensions, however, can only be increased until the penetration resistance equals the driving capacity of the largest pile driving hammers available. If additional bearing capacity is required to support the platform, the designer has to modify the design by either altering the platform configuration, changing the pile dimensions or resorting to the use of additional piles. Regardless of the alternative chosen, the overall cost of the platform can be expected to increase substantially. In such instances, the use of drainage piles to increase the bearing capacity without altering the design may prove to be an economically attractive alternative. Drainage piles may also find application in helping to increase the load-carrying capacity of existing platforms that fail to satisfy new or revised design criteria. In such platforms, the existing conventional piles could conceivably be converted into drainage piles, thereby increasing the load carrying capacity of the platform without increasing the pile dimensions.
Stable Platforms for the Launch and recovery of Submersibles
Authors: Estabrook Norman B. , Horn Henry M. 
Published: October 2008

Abstract
A new type of platoon has been developed from which submersible vehicles can be safely launched, recovered, and transported in heavy seas. An unpowered catamaran, this platoon offers unique advantages over conventional techniques by performing its functions while submerged below surface disturbances. To date, two such systems have been successfully operated with various submersibles in the Hawaiian Islands and off the coast of Southern California. Additional applications for this concept are seen in such areas as salvage, construction, and offshore oil recovery.

Introduction
Launching and recovering submersibles through the ocean interface has historically been a serious problem, particularly in rough seas. The lack of a safe, efficient, and economical means of handling these fragile vehicles is one of the reasons that the majority of them are currently not in use.
Characteristically, the methods commonly employed for launching and recovering submersibles fall into three categories; (1) cranes on board a mother ship, (2) special purpose ships, and (3) towing directly to and from dive sites. While it is not the purpose of this paper to evaluate these methods, it can safely be stated that as seas approach state 3, all of the currently employed techniques begin to break down with resulting hazards to equipment and personnel or cancellation of operations altogether.
A seemingly ideal solution to most of the problems associated with current handling techniques would be to use a large submarine which could travel great distances to and from a dive site if necessary, sink below all surface turbulence, and launch and recover a deep submersible vehicle (DSV) while underwater. Although this does not eliminate the very real problem of recovering a disabled submersible on the surface, it is mainly the economics of such a vessel which precludes any serious consideration of the method at present.
An attractive compromise to this "solution" is the use of a simple, un powered platfonn which can act as a stable base for transporting submersibles and which can hover below the surface for their safe launch and recovery.
Such a launch and recovery platform has been developed in Hawaii and utilized successfully for over 2 years in rough Hawaiian waters. Called the LRT for "Launch, Recovery, and Transport," it not only reduces the cost of handling deep submersibles, but also improves the reliability of operation in high sea states, thereby making the submersible, itself, more cost effective.

Design Requirements
A number of essential design requirements were initially established for the LRT platoon and may be summarized as follows:(available in full paper)
Advancement of Spar VIV Prediction
Authors: Yung T-.W. , Sandström R.E. , Slocum S.T. , Ding Z.J. , Lokken R.T. 
Published: October 2008

Abstract
Vortex Induced Vibration (VIV) of spar hulls is an essential operational issue in high current environments and an important consideration for mooring and riser integrity. Based on extensive analytical, laboratory, and field studies, ExxonMobil has developed a reliable methodology for predicting the VIV of classic spars, which has been validated by field measurements.
This paper extends our previous discussion of key issues related to reliable prediction of classic spar VIV. The main areas addressed in this paper include:Estimation of current drag using field measurementsPeak value statistics for the measured time seriesVIV lock-in dominanceSingle- versus multiple-degree-of-freedom motion

Introduction
Spar technology continues to evolve, and is currently seeing wide application in deep to ultra-deep water fields in the Gulf of Mexico (GOM). Eight spars have been installed in the GOM since 1996 and five more are in various stages of design and construction. These include classic spars (Deep Draft Caisson Vessel, or DDCV), truss spars and cell spars. A spar platform is characterized by a large, usually cylindrical, hull that extends deep into the water.
In the Gulf of Mexico, the presence of the loop current and loop current eddies introduce the potential to cause vortex-induced-vibration (VIV) on the spar hull (Figure 1). Speeds in these currents can remain high well below the surface, exposing the entire hull to large forces. In addition, hurricane currents may also cause VIV motion of the spar.
Field measurements have shown that all of the three classic spars (Hoover [1], Genesis [2], and Neptune [2]) have experienced VIV. From these experiences, we have observed that both loop/eddy currents and inertial currents (after a severe storm) could cause VIV. For the Hoover DDCV, eddy currents with speeds as low as one to two knots have induced VIV.
Figure 1 - Gulf of Mexico Currents (Available in full paper)
Industrial experience with VIV started many decades ago with the development of VIV suppression devices for smokestacks and chimneys (Figure 2). Over the years, there have been numerous studies on VIV physics as well as VIV suppression devices for onshore and offshore structures [3]- [6]. In recent years, there has been an increased interest in spar VIV design practice, highlighted by the first ever industry-wide workshop dedicated exclusively to spar VIV [2]. The October 2003 workshop addressed a wide range of topics, including regulatory perspectives, current VIV design practices, model test practices, field observations, and technology gaps. The workshop participants concluded that significant progress had been made, yet spar VIV prediction was still a challenging task. A part of the results from the workshop was incorporated into the new Appendix H - Spar Mooring Design for Vortex Induced Motion in RP 2SK Station-Keeping for Floating Structures.
NACE MR0175-2003 Impact on API 6A Equipment and Customers
Authors: Smith S.C. , Dufour J.D. , Wehner E.S. 
Published: October 2008

Abstract
API 6A "Specification for Wellheads and Christmas Tree Equipment" requires compliance with NACE MR0175 for equipment supplied for use in sour (Hydrogen Sulfide-H2S) service. Major changes to the NACE standard in the 2003 revision created the need for substantial changes to the API specification in terms of how both users and manufacturers specify equipment. New environmental restrictions have been imposed by NACE on many commonly used materials. Consequently, new material and temperature classifications have been created within the API document in order to permit compliance with these restrictions.
This paper reviews the background to the changes in the NACE standard, their effect on API 6A and some precautions that users of this equipment should consider. Additionally, upcoming changes to NACE MR0175 2003 with the 2004 publication of NACE MR0175/ISO 15156 will be discussed.

NACE MR0175 2003 Revision
NACE MR0175 prescribes the requirements for production equipment to be used in sour (hydrogen sulfide bearing) hydrocarbon service. Prior to 2003, it only addressed sulfide stress cracking (SCC) as a possible failure mode. Recognizing this, NACE formed the CRA (Corrosion Resistant Alloy) Rewrite Committee to address some of the perceived shortcomings of the earlier revisions. These included:Catastrophic failure mechanisms other than (SSC) were not included in the scope of the document, but other mechanisms such as chloride stress corrosion cracking (SCC) may be the limiting factor in a sour environment.Many environmental parameters important to a material's susceptibility to environmental cracking (SCC or SCC) were not adequately addressed. Depending on the specific alloy, these could include temperature, partial pressure of H2S, chloride concentration, presence of free sulfur, temperature, and other factors.In the last ten years or so, there has been a growing trend to include environmental restrictions that define the safe operating limits for new alloy additions to MR0175. Many of the materials included in earlier editions have a limit on maximum hardness and possibly heat treat condition, but no environmental restrictions. This gave the wrong impression that these materials were safe to use under all environmental conditions.The balloting and approval process to add new alloys was unrealistically long - in some cases years. The resultant work of the CRA Rewrite Committee formed the basis for the changes found in NACE MR0175- 2003: Standard Material Requirements: Metals for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments".
Historically there have been few revisions to MR0175 that have impacted the acceptability of previously approved materials. Typically, the revisions have added new alloys, modified test environments, etc. The 2003 revision, however, presents a new approach for selecting materials for use in sour service.
Mobility of Large Sediment Features In the Southern North Sea
Authors: Cloet R.L. 
Published: October 2008

Abstract:
This paper examines areas of seabed instability along the east coast of England and Scotland. It demonstrates the existence of sediment circulation patterns which slowly evolve. When spoil deposits are injected in such systems they are seen to accelerate the process. However, an understanding of such circulations may permit the system being used for natural storage of spoil where a build up of a shoal can be tolerated.
Mobility of Large Sediment features in the Southern North Sea:
The east coast of U.K. is characterised by the existence of large sandbodies which can attain lengths of 25 miles, and may be 8 - 9 miles wide. It is also a coastal area which has known intensive navigation for several centuries and some surveys acceptable by present day standards have been made for almost 200 years. These hydrographic surveys were and still are subjective to a degree, in the sense that the surveyors experience and local knowledge make a significant difference to the quality of the survey. They contain a deliberate bias towards better consistency in the depth ranges of 3 to 6 fathoms which for over a century has been the warning depth zone for shipping or in deeper water show a marked preference for the shoaler soundings. During the last decade navigational attention has shifted dramatically to the 10-15 fathom depth range because the size of ships has increased enormously. The consequence has been a vastly increased need for new hydrographic surveys in areas where little or no historical knowledge exists of either the shape of the seabed, or its stability. In existing surveys in areas which have frequently been examined the information is not as reliable as at shoaler levels. The adequacy of available means to delineate the seabed accurately is the subject of another paper, being presented at this Conference (1), whereas the present paper deals with the question of relative stability of the seabed and the consistency of the movement to which it is subjected.
The first example is a channel system in the Outer Thames Estuary (fig. 1, 2) called the Edinburgh Channels, which for a period of about a century traversed a major sandbank, the Long Sand, at a point where it is some 5 miles wide, which until recently, provided access by major shipping to the Port of London by a shorter route than the one now in use. The historical development of these channels is shown in Fig. 3 for the period 1839 to 1962. Initially a shallow cut is seen almost to cross the bank from SE to NW, but of more interest at this stage is the growth of two converging "spits", one from Knock John bank eastward, and the other from Long Sand westward. The sequence shows it took about 60 years for the convergence to build a new bank about 3 miles long by a mile wide, and at one point over 40 feet in thickness when referred to the 1839 surface.
Na Kika's Dynamic Model Operator Training Simulator
Authors: Dziubla P.W. , Lang P.P. , Lindsay M.S. , Sanders D.L. , Shepard N.H. 
Published: October 2008

Abstract

Introduction
The Na Kika project is among the most complex subsea developments executed by our industry and faced a number of unique flow assurance challenges due to the extreme water depth (5800 to 7600 ft), distributed well layout, variability in produced fluids (from six distinct fields), offsets of up to 26 miles and relatively low temperature reserves. Flow assurance strategies thus were a key driver to system selection and overall assessment of project profitability. This paper gives an overview of the development of the fully integrated dynamic simulator that incorporated flow assurance and other novel processes into a unique training strategy for successful operation of the Na Kika host and subsea systems.

Background
The Na Kika project consists of six oil and gas fields in the Mississippi Canyon area of the Gulf of Mexico that are tied back to a semi submersible based floating production facility in 6350 ft of water. Water depths range from 5800 to 7600 ft. The individual fields in the Na Kika base development are Ariel, Kepler, Fourier, Herschel, and East Anstey, each of which will be developed as subsea fields with produced fluids routed back to a floating host roughly located in the center of the development area. See Figure 1. The sixth field, Coulomb, will be produced by a single flowline back to the Na Kika processing facility. Offset distances from the host are in the range of 5 (Ariel) to 26 miles (Coulomb).
The Na Kika subsea layout consists of a single, 10" × 16" pipe-in-pipe flowline loop for those fields north of the host (Ariel and Kepler). On the south side, there are two flowline loops, an 8"x12" pipe-in-pipe insulated oil loop for the Herschel and selected Fourier wells, and an 8" un-insulated gas loop for the East Anstey and selected Fourier wells. The subsea system at Fourier includes the flexibility to allow wells to produce back through either the gas or the oil flowlines, particularly with jumper reconfiguration. Production from the Coulomb wells, which lie south of the host, will be transported by a single 26-mile flowline back to the host. This subsea architecture deviates significantly from earlier projects through the use of flowline loops, as opposed to dual lines to a manifold, and the use of a single flowline for the Coulomb gas wells.

Hydrate Control and Remediation Strategy
All deepwater subsea projects have hydrate concerns due to the fact that hydrocarbon systems fall into the hydrate stability regime at the typical seabed temperature of 39 ÂºF when pressures exceed 400 to 600 psig. Hydrate control and remediation is a particular concern for Na Kika due to the extreme water depth at the location, which leads to high hydrostatic head, and the downward slope of the flowlines on the north side of the host. The single flowline tieback for the Coulomb gas wells introduces additional hydrate risks and concerns, including the effectiveness and safety of single sided blowdown for hydrate remediation.