bluuebunny/crossref_metadata_2025 huggingface dataset:
Underwater Monitoring Network
Authors: Brevik Arild
Published: June 2014

This paper presents current technology and research activities related to underwater monitoring. Main focus is directed towards the wireless solutions, built with basis in underwater transponder technology where wireless communication is implemented through acoustic communication. The communication network described is a multi-hop network with autonomous handling of critical tasks as signal routing, and capable of handling both stationary and mobile sensor node within the network.

Sensornodes in the network is built by interfacing various subsea sensors to the network communication transponders or AUV's. R&D is also including a cabled infrastructure that can be used together with the wireless solution. Different sensors are selected based on the application targeted, like acoustic sonars or dissolved hydrocarbon sniffers for subsea leak detection. The goal for these R&D activities is to develop and test a versatile and scalable system that can be tailored to different applications, including environmental, military or surveillance in order to effectively provide real-time subsea data to topside.
A Dry Tree Semisubmersible Floating Production Unit Alternative for Field Developments
Authors: Korsnes J. , Noce R.
Published: June 2014

This paper presents the main design and performance characteristics of the Octabuoy® Classic (Octabuoy) for field developments. The focus of the paper shall be on evaluating the Octabuoy's performance when it comes to its value as a dry tree floating production system with optional drilling capability. The value is measured in terms of floater's robustness and flexibility for said applications. In turn, robustness and flexibility are achieved utilizing low-motions hull design, wide range topside load carrying capability the use of standard riser and wellbay components for different water depths. Results and corresponding conclusions of analyses aimed at determining the technical feasibility and economic viability of the Octabuoy hull for field developments in various regions of the world, water depths, drilling options, and payloads will be included. The Octabuoy is the first dry tree semisubmersible platform, which has been sold and built. It has undergone extensive numerical analyses and model testing, which indicate that the Octabuoy's deep draft and overall hull geometry are instrumental in ensuring superior performance and cost effectiveness. The associated minimal motion characteristics and the design of the Octabuoy allow for flexibility in the selection of riser configurations (traditional top-tensioned production risers or SCRs); a variety of installation options (quayside, offshore heavy lift, float over); use in both benign and harsh environments; drilling options; and relocation of the platform from a depleted field to another field.
Novel Dry-Tree Semisubmersible Solutions for Deepwater Marginal Field Development
Authors: Mansour Alaa M. , Kumar Dhiraj , Zuccolo Ricardo , James Jolly , Heidari Homayoun
Published: June 2014

Often the requirements for dry—tree completion, direct vertical access (DVA) to production wells, as well as the ability to perform drilling and work-over from the production platform, due to operational, economic, or reservoir requirements, necessitate the use of Top Tensioned Risers (TTRs). Due to stroke limitations on the currently qualified tensioners’, TTRs are required to be hosted on a floating system with minimal heave response. To date, the floating systems of choice to host TTRs were Spars and TLPs, with the former being the floater of choice for water depth beyond 6,000ft.

Conventional semisubmersible design has a number of significant advantages. These include provision of significantly larger and more ventilated deck area; ability to integrate the hull and topside at the quayside or via dry-mating at the fab yard; and lower risk and better economic for offshore installation operations compared to the Spars where they require upending and offshore deck lift operations. Additionally, the semisubmersible platforms are more flexible with respect to maximum payload. However, conventional semisubmersibles heave response is not suitable for TTR applications.

This paper presents invovative semisubmersible designs, which provides suitable motion characteristics for hosting TTRs, while maintaining the advantages of semisubmersibles floaters.

For development of marginal fields, it is essential to minimize the total cost of the project in every phase. This includes realizing the savings from using DVA to wells, adopting quayside integration or dry-mating of topside to hull and avoiding the need for offshore lift operations. These measures can be achieved by developing semisubmersible designs which provide better motion characteristics suitable for TTRs and Dry-Trees.

Two state-of-the-art high performance semisubmersible designs have been presented here and evaluated for the development of marginal fields in deepwater Gulf of Mexico (GoM). These designs are the Fee-Hanging Solid Ballast Semi (FHSB Semi) and the Damper Chamber Column Semi (DCC Semi). Detailed description of these novel designs and their performance in the deepwater GoM Central region, as well as the performance of the associated TTR systems are presented. Furthermore, project risks and their proposed mitigation measures for these two novel designs are also investigated and reported.

The paper concludes with discussions on the project execution plan, cost and schedule benefits when developing marginal fields using the two presented novel designs.
Safety Systems for Subsea Applications
Authors: Curran Christopher J.
Published: June 2014

Regulatory agencies have established certain requirements for the design, installation, and operation of offshore production facilities. This paper presents a systematization of proven practices for providing a basic safety system for subsea applications. Proper application of these practices, along with good design, maintenance and operation of the entire production facility, should provide an operationally safe system. This paper presents recommendations for designing, installing, and testing a basic safety system for subsea applications. The basic concepts of subsea safety systems, protection methods, and requirements of the system are discussed and outlined.

For the purposes of this paper, ‘subsea system’ includes all process components from the wellhead (and surface controlled subsurface safety valve [SCSSV]) to the topside boarding valve. This paper illustrates how system analysis methods can be used to determine safety requirements to protect any process component. Actual analyses of the principal components are developed in such a manner that the requirements determined will be applicable whenever the component is used in the process. The safety requirements of the individual process components may then be integrated into a complete subsea safety system. The analysis procedures include a method to document and verify system integrity. After a production subsea safety system is placed in operation, this paper discusses the procedures that should be established to verify continued system integrity.

This paper highlights the operating modes of the safety system:automatic monitoring and automatic protective action if an abnormal condition indicating an undesirable event can be detected by a sensor,automatic protective action if manually actuated by personnel who observe or are alerted to an unsafe condition by an alarm, andcontinuous protection by support systems that minimize the effects of escaping hydrocarbons or other undesirable events.. The cause(s) of the undesirable events are determined from a detailed investigation of the failure modes of the component. The safety analysis of each process components associated with the operating modes highlights undesirable events (effects of equipment failures, process upsets, accidents, etc.) from which protection should be provided, along with detectable abnormal conditions that can be monitored for safety surveillance.

The paper addresses the importance of proper analysis and design of a subsea safety system in order to focus on personnel safety, preventing releases of hydrocarbons, stopping the flow of hydrocarbons resulting from a loss of containment if it occurs as well as preventing and mitigating the ingress of seawater resulting from a loss of containment in an under pressure system scenario.
Qualification of a Subsea Separator with On-line Desanding Capability for Shallow-water Applications
Authors: Olson M.D. , Grave E.J. , Juarez J.C. , Anderson M.R.
Published: June 2014

ExxonMobil Development Company (EMDC) recently completed a qualification program which included a multiphase, subsea separation system for shallow-water applications. This paper summarizes the results from this qualification program.

Developments and advances in subsea processing technologies and the application of such technologies have been fueled by recent economic considerations in the oil and gas industry, as fields are maturing and operating companies strive to maintain oil and gas production. To-date, companies have executed project-specific qualification programs which take years of upfront engineering. The intent of this qualification program was to develop subsea separation technologies for the "global" subsea portfolio, rather than a specific project.

To cover the "global" subsea portfolio, a separator design was chosen that would meet separation performance targets over a wide range of operating conditions. For subsea applications, availability and reliability is critical, as unplanned intervention costs are extremely high; therefore, only certain internals were recommended to avoid plugging and fouling issues. Also, the separator was equipped with sand handling internals, including sand jetting headers and sand removal cyclones, to allow online fluidization and removal of accumulated sand. Qualification activities included the development of a subsea processing template, design validation of a multiphase separator design using Computational Fluid Dynamics (CFD) and performance tests with model fluids and "live" fluids, and performance tests on the sand handling equipment. High-level results from these tests are shared.

Prior to the qualification programs, experience with subsea separation technologies, and subsea processing as a whole, within ExxonMobil was limited to being an active partner with subsea processing projects such as Tordis and Pazflor. Following the execution of the aforementioned qualification programs, technical risks have been mitigated, such that it is now possible to be confident in applying these technologies in the "global" subsea portfolio. This will enable ExxonMobil to reduce the cost and schedule impact of upfront engineering on future subsea processing projects. In the ever-changing business environment of the oil and gas industry, this may become a preferred approach to bring unproven technologies to maturity when the business need is well-established.
Low Motion Semisubmersible Hull for Dry Tree Application
Authors: Kyoung Johyun , O'Sullivan Jim , Kostas Lambrakos , Whan Kim Jang , Ermon James
Published: June 2014

For three different marginal fields with different payloads, two variations of Technip's wet tree HVS semisubmersible are designed for dry tree application and evaluated on the basis of riser tensioner stroke and deck acceleration. These dry tree suitable hulls also have reduced vertical heave motion at the SCR porch and improve quayside integration and commissioning of topsides to the hull.

A key element for the dry tree platform is the riser tensioning system which supports the direct vertical production risers from a subsea wellhead to a topside production tree. These riser tensioners provide additional hull heave stiffness, and effectively reduce the overall natural heave period of the hull. Conventional semisubmersible designs have excessive heave response in harsh environments, resulting in tensioner stroke ranges that are beyond the stroke ranges of field proven conventional riser tensioner equipment.

The HVS class semisubmersible with reduced heave and VIM response was chosen as the basis for the dry tree semisubmersible designs in order to achieve riser tensioner stroke ranges within the capability of field proven riser tensioners. The main characteristic of the HVS class of semisubmersible is the redistribution of displacement from the pontoons to the lower part of the column. This is accomplished with a column step, which has the appearance of a blister, located partially around the lower part of column. This redistribution reduces the vertical hydrodynamic excitation, and the heave response. The column step breaks also the coherence of the vortex shedding along the length of column and consequently suppresses the vortex induced motion. The dry tree adaptations of the HVS class semisubmersible include pontoon plates that increase the heave natural period through added mass, and the outcome is reduced heave motion for seastates with high peak periods. The pontoon plates are simple structures to fabricate and have additional benefit of enhancing structural rigidity. The contribution of the pontoon plates to the hull steel weight is minimal. With optimal design of the pontoon plates, the resulting dry tree hulls support the top tensioned risers without the need of a keel guide.

The dry tree hull forms have been designed using Computational Fluid Dynamic (CFD) analysis. Extensive CFD work was performed in order to finalize the dry tree designs.
Seabed Friction On Carbonate Soils: Physical Modelling of Axial Pipe-Soil Friction
Authors: Boylan N.P. , White D.J. , Brunning P.
Published: June 2014

This paper is concerned with the ‘friction’ and ‘sliding resistance’ that can be mobilised on the unusual carbonate sediments prevalent across many parts of the world, including Offshore Australia. Physical centrifuge model testing was conducted to evaluate the axial pipe-soil resistance on a soil obtained from the North West Shelf, offshore Australia. Tests were performed at a range of speeds, spanning drained/undrained conditions, interspersed with consolidation periods. The resulting axial friction factors are generally higher than is often assumed in conventional design practice for pipeline end expansion or buckling and walking analysis, which is consistent with the high friction angles and dilatancy of these angular carbonate soils. In addition, the results demonstrate the effect that soil drainage response and history of pipeline sliding movements can have on the axial-pipe friction. Overall, the results highlight the importance of making site-specific assessments of seabed sliding resistance, rather than rely on non-site-specific results (particularly from different regions) that may display a very different soil response. Lastly, recommendations are made for design assessments of the sliding resistance of carbonate soils.
Core scale Evaluation Of Geomechanical Property Related To Gas Production From Gas Hydrate Deposits In The Ulleng Basin, East Sea, Korea
Authors: Lee Joo Yong , Lee Jaehyung , Kim Se Joon , Ahn Taewoong
Published: June 2014

The production of natural gas from gas hydrate deposits poses chalenges such as assessing hydrate recovery rates from physical properties and geological structure of the hydrate reservoir, securing the economic viability of produced gas from a particular resource, and keeping process safe from geomechanical impacts from hydrate dissociation. The macro scale behavior of sediments during production operations, such as particle migration, fluid flow, and deformation behavior, is governed by particle characteristics, fabric formation environments, and the resulting fabrics. The geotechnical terms for characterizing the grain size distribution are useful tools for estimating geotechnical parameters in the absence of an extensive set of the geotechnical laboratory experiments. In this manuscript, the grain size distributions of sediments from the Ulleung Basin will be utilized to characterize geomechanical behaviors induced by the production operations at gas hydrate-bearing sites in the Ulleung Basin, where pore-filling GH have been found in the intercalated turbidite sands. According to the analyses on the grain size distributions, the particle migration in coarse grained layers during production necessitates proper measure for sand productions, while fine grained layers are mostly self-filtering. The hydraulic conductivity in pore-filling gas hydrate-bearing layers is relatively low in comparison with those from conventional gas reservoirs, and the conductivities at layers above GH layers are low enough to function as barriers.
API 17G Specification for Subsea Well Intervention Equipment
Authors: Stawaisz Ray , Muff David Anthony , Skeels Brian
Published: June 2014

This paper overviews the proposed API 17G Specification, assisting the reader in navigating the lengthy document. The results of this paper for the reader will be a simplification of the proposed Specification and an understanding of the safety philosophy and strategy which is the core upon which system analysis, equipment design, equipment qualification and material/manufacturing specifications are based. The document stops short of addressing HPHT until the task group has time to review and incorporate API 17TR8.

This proposed specification is intended to illustrate current technology and design practice along with structuring its format to accommodate future intervention technologies and hardware. It is also intended to provide the necessary safety review and campaign planning tools needed by of the offshore community for subsea well intervention and workovers, similar to those now being incorporated into offshore floating drilling practices.
Managing the Risk of the Unknowns: Åsgard Subsea Compression Qualification Program
Authors: Hedne Pål
Published: June 2014

The Åsgard field was started up in 1999 and comprises the Smørbukk oil and Midgard gas assets. Midgard is developed with three subsea templates located approximately 45 km (31 miles) from the Åsgard field centre. Additionally, the gas field Mikkel located nearly 40 km (25 miles) further away is tied back to Midgard. To extend the life time of the Åsgard Field and achieve Increased Gas Recovery (IGR), boosting of well stream is necessary. Since 2005 Statoil has matured two concepts in parallel, a compressor platform and a subsea compressor facility. In October 2010 it was decided to go forward with the subsea facility. The Åsgard Subsea Compression (ÅSC) project is now building the world's first Subsea Compression Station (SCSt). ÅSC will be ready for operation in 2015 and secure production of 282 MMboes from the Åsgard field up to 2029.

The ÅSC SCSt will include two individual compressor train installed in a shared template with a total weight of 5100 tonnes, a footprint of more than 3300 m2, and height around 26 meters. The project includes novel technology especially related to gas compressors and subsea power distribution.

To mature the concept, a comprehensive Technology Qualification Program (TQP) was initiated in 2007 covering activities related to the following main building blocks:Process modules (coolers, scrubber, pump and compressor)Power system (long step out with topside Variable Speed Drive (VSD), transformers, HV swivel, connection system, umbilical / power cables)Control system (process, AMB and anti-surge)in addition to Hot-tap, remotely installed retrofit tee on the Midgard pipeline

The total qualification program included nearly 50 activities. Attention was given to define the TQ's in terms of gap analysis and failure modes, to ensure that the acceptance criteria reflected the necessary gathering of evidence to proof the equipment fit for service. The qualification has been done in collaboration with a series of vendors and research institutes. A large scale laboratory facility has been built at Statoil's R&D centre K-lab at Kårstø for testing gas compressors and long step-out power systems. The results from this work have been of crucial importance in maturing the subsea compression concept to the necessary level.
Challenges Associated with Electrical and Optical Cable Terminations and Connector Systems for the Drilling Industry
Authors: Brown Gary , Lewis Karen
Published: June 2014

The challenges associated with the design, manufacturing and testing of underwater electrical and optical cable termination and connector systems for the Drilling Industry are vast and far-reaching. No longer are connectors only being supplied, but also complete systems, such as fully terminated umbilicals. For connectors that need to be installed in the field, sometimes in extremely arduous conditions, designs need to overcome the effects of pressure and temperature at ultra-deep sea-depths and to be strong enough to withstand the rough handling topside and rough environmental stress of being within close proximity to drilling systems activity. To meet the challenges and enable continuous improvements, connector companies cannot focus solely on connectors, they must see the future of cable terminations and connectors and their synergetic relationship to the umbilicals and cables.
Olympus TLP- Design and Construction Embedded in a "I Care" Culture
Authors: McGlothlin Terry
Published: June 2014

Mars B's approach to HSE is embodied in the HSE Vision and Values, adopted early in the project's design phase:

This consistent focus on a caring culture and managing risks to ALARP has manifested itself in a robust design with novel process safety design improvements, notably in the areas of passive hull, riser isolation, temporary refuge integrity, and drilling rig automation. In fabrication, installation, and commissioning, the project has built on the safety successes of the Perdido Project, with nearly a 25% reduction in recordable injury rate.

Specific actions taken during project planning and execution have enabled Mars B's HSE successes in both personal and process safety:Process Safety EnablersPersonal Safety EnablersEarly identification of Safety Critical ElementsClear ownership of Safety Critical Elements within the Design TeamPerformance Standards, including robust verification and assurance processes.Hazard Management Hierarchy inherent in design decisions.Front-End Loading of Technical Safety requirements.Transparent process for ALARP decision making.Early and frequent HSE engagement with contractor managementEmpowered and competent site teams, fostering a culture of initiative and interventionFocus on frontline leadership accountability and commitmentVisible and Felt Leadership: tangible demonstration of care for workforce (leadership site visits, recognition events, PPE, training opportunities)

Mars B's approach to HSE is embodied in the HSE Vision and Values, adopted early in the project's design phase:

This consistent focus on a caring culture and managing risks to ALARP has manifested itself in a robust design with novel process safety design improvements, notably in the areas of passive hull, riser isolation, temporary refuge integrity, and drilling rig automation. In fabrication, installation, and commissioning, the project has built on the safety successes of the Perdido Project, with nearly a 25% reduction in recordable injury rate.
sgard Project - Another Step Versus the Full Subsea Process Plant
Authors: Micali Salvatore
Published: June 2014

Any new techniques that can improve traditional methods of production and offer increased recovery are eagerly sought after by the oil and gas industry. Among those, subsea gas compression systems are being recognized as the best solutions for both improved recovery and access to stranded reserves.

Indeed, after several years of design, qualification and testing, today the subsea gas compression technology is an economically feasible way to compensate the gas reservoir pressure depletion.

This paper will present the Åsgard project, the first commercial project applying the subsea compression technology. Considering the complexity and at the same time the robustness of the system proposed, with this project the subsea technology will do another important step to reach the full subsea process plant vision.
Iceberg Scouring on the Norwegian Continental Shelf
Authors: Lien Reidar
Published: June 2014

This paper is a condensed version of parts of a Dr. ing. thesis to be presented during 1983 (1). The first part of the paper deals with the regional distribution of iceberg scouring on the Norwegian continental shelf, and some general aspects related to it. The second part deals with iceberg scouring as a 1ocal phenomenon and its relation to the sea floor topography, sediment distribution, and geological and geotechnical properties of the sediments.

INTRODUCTION

Iceberg scouring on the European side of the Atlantic Ocean was first reported in 1973 (2, 3). The investigations reported were carried out north and west of the British Isles (3) and in the vicinity of the Norwegian Trough (2). Belderson and Wilson (2) suggested that the iceberg plough marks also should be found in parts of the Norwegian slope and shelf areas shallower than 500 m. Later these features have been described from several areas of the Norwegian shelf (4,5,6,7,8).

In areas with scars made by grounding icebergs, they highly influence the sea floor conditions both With regard to the topography of the sea floor, and the geological and geotechnical properties of the sea floor sediments. These are all decisive factors, both with respect to technical solutions and economy, when structures or pipelines are to be installed on the shelf. The shapes and sizes of the scars vary considerably. They have been recorded more than 20 m deep, more than 250 m wide and several kilometres long. They are all fossil.

GENERAL DISTRIBUTION OF ICEBERG SCOURING

The map in Fig. 1 gives an overview over the distribution of iceberg scouring on the Norwegian shelf from about 58 N to about 72 N. The map is mainly based on side-scan sonar, boomer, and sparker records obtained during the Continental Shelf Institute's regional map- ping program. This program has a general profile grid (Fig. 2) where the main profiling directions broadly are perpendicular to the coast, and the crossing profiles run parallel to the coast. The distances between the main lines are about 10 km, and the crossing lines are about 25 km apart. Besides the information from this program, data from site surveys and other special investigations are also comprised.

As it can be seen from Fig. 1, large areas of the continental shelf are infested by iceberg scouring. As Belderson and Wilson (2) showed, there are iceberg scars on both sides of the Norwegian Trough (Figs. 1 and 3), but it is especially on the eastern slope of the trough and northward that we find the most intense scouring. Between the 61, parallel and the 71, parallel about 55% of the shelf shallower than 500 m are iceberg scoured. The iceberg scouring is mainly recorded in water depths between 100 m and 500 m. From the distribution map in Fig. 1, we can observe that, in general, the continental slope and the protruding banks on the shelf were most exposed to grounding icebergs.
A Deepwater Vessel and Riser Monitoring Program
Authors: Kotch M.A.
Published: June 2014

A Deepwater Vessel and Riser Measurement Program collected 93 days of data describing 83 channels of environmental conditions, vessel response, and riser response in 1700 feet of water in the Gulf of Mexico. On the order of 10 million data measurements were recorded using a minicomputer-controlled data acquisition system. This program has produced the most comprehensive and extensive field database for such systems to date.

INTRODUCTION

Recently our client was preparing to drill several exploratory wells in deepwater in the Gulf of Mexico. In planning these operations it was desirable to conduct analyses of the expectable behavior of the moored semi-submersible drilling vessel and the marine riser.

The computer programs used for these analyses require as their input a description of the expected environmental conditions. Our client did not possess a comprehensive database which described these environmental conditions In the area of interest. Moreover, the output of these computer programs had not, in large part, been verified to any degree with field data. A database which also contained measured vessel and riser responses could be used for this purpose.

Our c1ient also wanted to obtain better information concerning the ordinary range of operating conditions from a drilling program management point of view, particularly for the riser. As an example, it is commonly presumed that a moored semi-submersible drilling vessel typically operates within 1% of the hole nearly all the time, but Whether or not this was in fact the case could not be confirmed, nor was a distribution available as to "what percent of the time could the vessel be expected to be more than 1% of water depth away from the hole, more than 2%, etc.?".

Systems Management and Engineering Corporation was contracted to obtain this information by assembling and operating a comprehensive data acquisition system, and to reduce the acquired data. This paper' describes the design, installation, and operation of the system instrumentation hardware and software. An outline of the data reduction performed to date is also presented.

SYSTEM DESIGN

In planning the Deepwater Riser and Vessel Measurement Program (hereafter referred to as DWMP), we first separated the data to be measured into the three general categories of Environmental Conditions, Vessel Responses, and Riser Responses. The parameter's which we desired to measure in these categories are given in Table 1.

For the Environmental Conditions it was decided that wind, wave, and current information was sufficient as these are the only parameters which significantly affect vessel and riser response and are used as input to an.1ysis programs.

The Vessel Responses and Riser Responses to be measured were also based on the input requirements and output provided by vessel and riser programs, together with what was felt useful for operations planning. These included vessel mean position and dynamic motions, and riser axial and bending loads, motions, and inclinations.
Case History: Development Of A Reliable Subsea Safety System For Deepwater Drillstem Testing
Authors: Allred W.R. , Clark J.A. , Lorenzo Pretto , Lorefice Roberto
Published: June 2014

With the expansion of offshore drill stem testing (DST) to applications in water depths approaching 8,000 feet [2,430.4 m], subsea safety valve equipment has had to undergo reconfiguration to support testing requirements at the increased depths. One of the primary operator concerns for deepwater conditions has been the capability of the subsea test tree to meet the required time constraints for closing and unlatching at the increased depths, In the case of dynamically-positioned drilling ships, for example, the riser must be disconnected in approximately 20 seconds in the event of an emergency.

To address the safety needs and comply with the closing requirements of systems at depths greater than 3,000 feet [914.4 m], a computer simulation program was developed to design the most efficient hydraulic circuit possible. As a result of the newly-designed hydraulic circuit, a new actuator for use in deepwater testing applications was also developed.

This paper will discuss use of the simulation program and newly-developed actuator and will present a case history that documents the development and capabilities of the first subsea safety system configured for deep water with the new simulation program.

The system that was developed operated successfully from a floating rig for 80 days in water depths of 2,700 feet [823 m]. However, the system was designed to operate at depths of up to 8,000 feet [2,430.4 m]. During drill stem testing operations, the time requirements of less than 20 seconds for closing the retainer valve and closing and unlatching the subsea test tree were met with more than 3,300 feet [924.4 m] of hose. These closing times would not have been possible with traditional equipment.

DEVELOPMENT OF THE SYSTEM

Before an appropriate deepwater subsea system design can be developed, operator requirements must be determined. The data required for development of this system are listed below:

Wellhead and Blowout Preventer System (BOP)

Wear bushing - This is the position at which the subsea safety systems are landed in the wellhead. The position of the wear bushing in relation to the datum line controls the location of the subsea tree in the BOP stack. Wellhead profile angle-This information is needed to insure that the proper fluted hanger profile is selected according to the wear bushing profile. Internal diameters of the BOP stack - These measurements are needed to properly select the subsea equipment needed for the job. Size and type of rams - This information ensures proper sealing of the variable or fixed-type rams on the slick joint. Arrangement of BOP stack - The location of the rams &d kill 'lines is very critical in knowing where to place the subsea test tree. At least one pipe ram must be able to close around the slick joint of the subsea test tree and have a kill line below that closure. The shear ram must be in a position to cut the shearable handling sub in the event all other alternatives to closing in are exhausted.
Structural Reliability Assessment of the Oman India Pipeline
Authors: Al-Sharif A.M. , Preston R.
Published: June 2014

Reliability techniques are increasingly finding application in design. The special design conditions for the deep water sections of the Oman India Pipeline dictate their use since the experiences basis for application of standard deterministic techniques is inadequate. The paper discusses the reliability analysis as applied to the Oman India Pipeline, including selection of a collapse model, characterization of the variability in the parameter that affect pipe resistance to collapse, and implementation of first and second order reliability analyses to assess the probability of pipe failure. The reliability analysis results are used as the basis for establishing the pipe wall thickness requirements for the pipeline.

Introduction

One of the principal aims of engineering design is the assume of system performance within economic constraints. The commonly used approach of designing by deterministic safety factor has several limitations, e.g., it tends to be overly conservative for many practical situations and it does not provide any qualification of the design reliability. The form has obvious economic implications and the latter fails to deliver the needed input for the risk evaluation and decision making process. These limitations become sharply focused in a design situation which is inherently probabilistic due to the natural variability and uncertain associated with the analysis, installation and service conditions associated with a high cost deep-sea pipeline.

For better utilization of resources, justified levels of safety, and improved quantification of risks, alternative approach of probabilistic design needs to be considered. In this approach the design evaluation explicitly accounts variability and uncertain in key parameters ormodels pertinent to the design process.

The condition of any structure with respect to failure can be described as being in the safe state or the filled state. The between these states is the so-called limit state. The limit states considered in the design of the Oman India Pipeline 1 are:Serviceability limit state (loss of stability, yielding).Fatigue limit stateUltimate limit state (local buckling, bursting).Progressive limit state (progressive buckling, rupture).

This paper is limited to probabilistic design against local buckling under hydrostatic pressure and bending. It describes the methodology, associated assumptions and statistical characterization of input parameters for the pipeline structure reliability analysis. Other limit states have been considered as pat of the overall design philosophy for the pipeline, but are not presented here.

Deterministic Buckling Model and Loading Conditions

Failure Model. The Oman India Pipeline will utilize many thousands of individually manufactured large diameter, thick-wall pipe segments of X-70 grade line-pipe steel. The pipeline is subjected to high external pressure due to water depth and bending during installation and potentially during operation For these conditions, the generally expected (governing) mode of is plastic collapse.
Aspirin Activation of Eosinophils and Mast Cells: Implications in the Pathogenesis of Aspirin-Exacerbated Respiratory Disease
Authors: Steinke John W. , Negri Julie , Liu Lixia , Payne Spencer C. , Borish Larry
Published: June 2014

Reactions to aspirin and nonsteroidal anti-inflammatory drugs in patients with aspirin-exacerbated respiratory disease (AERD) are triggered when constraints upon activated eosinophils, normally supplied by PGE2, are removed secondary to cyclooxygenase-1 inhibition. However, the mechanism driving the concomitant cellular activation is unknown. We investigated the capacity of aspirin itself to provide this activation signal. Eosinophils were enriched from peripheral blood samples and activated with lysine ASA (LysASA). Parallel samples were stimulated with related nonsteroidal anti-inflammatory drugs. Activation was evaluated as Ca2+ flux, secretion of cysteinyl leukotrienes (CysLT), and eosinophil-derived neurotoxin (EDN) release. CD34+ progenitor-derived mast cells were also used to test the influence of aspirin on human mast cells with measurements of Ca2+ flux and PGD2 release. LysASA induced Ca2+ fluxes and EDN release, but not CysLT secretion from circulating eosinophils. There was no difference in the sensitivity or extent of activation between AERD and control subjects, and sodium salicylate was without effect. Like eosinophils, aspirin was able to activate human mast cells directly through Ca2+ flux and PGD2 release. AERD is associated with eosinophils maturing locally in a high IFN-γ milieu. As such, in additional studies, eosinophil progenitors were differentiated in the presence of IFN-γ prior to activation with aspirin. Eosinophils matured in the presence of IFN-γ displayed robust secretion of both EDN and CysLTs. These studies identify aspirin as the trigger of eosinophil and mast cell activation in AERD, acting in synergy with its ability to release cells from the anti-inflammatory constraints of PGE2.
Bovine γδ T Cells Are a Major Regulatory T Cell Subset
Authors: Guzman Efrain , Hope Jayne , Taylor Geraldine , Smith Adrian L. , Cubillos-Zapata Carolina , Charleston Bryan
Published: June 2014

In humans and mice, γδ T cells represent <5% of the total circulating lymphocytes. In contrast, the γδ T cell compartment in ruminants accounts for 15–60% of the total circulating mononuclear lymphocytes. Despite the existence of CD4+CD25high Foxp3+ T cells in the bovine system, these are neither anergic nor suppressive. We present evidence showing that bovine γδ T cells are the major regulatory T cell subset in peripheral blood. These γδ T cells spontaneously secrete IL-10 and proliferate in response to IL-10, TGF-β, and contact with APCs. IL-10–expressing γδ T cells inhibit Ag-specific and nonspecific proliferation of CD4+ and CD8+ T cells in vitro. APC subsets expressing IL-10 and TFG-β regulate proliferation of γδ T cells producing IL-10. We propose that γδ T cells are a major regulatory T cell population in the bovine system.
Accumulation of Serial Forces on TCR and CD8 Frequently Applied by Agonist Antigenic Peptides Embedded in MHC Molecules Triggers Calcium in T Cells
Authors: Pryshchep Sergey , Zarnitsyna Veronika I. , Hong Jinsung , Evavold Brian D. , Zhu Cheng
Published: June 2014

T cell activation by Ag is one of the key events in adaptive immunity. It is triggered by interactions of the TCR and coreceptor (CD8 or CD4) with antigenic peptides embedded in MHC (pMHC) molecules expressed on APCs. The mechanism of how signal is initiated remains unclear. In this article, we complement our two-dimensional kinetic analysis of TCR–pMHC–CD8 interaction with concurrent calcium imaging to examine how ligand engagement of TCR with and without the coengagement of CD8 initiates signaling. We found that accumulation of frequently applied forces on the TCR via agonist pMHC triggered calcium, which was further enhanced by CD8 cooperative binding. Prolonging the intermission between sequential force applications impaired calcium signals. Our data support a model where rapid accumulation of serial forces on TCR–pMHC–CD8 bonds triggers calcium in T cells.
Cutting Edge: Antigen-Specific Thymocyte Feedback Regulates Homeostatic Thymic Conventional Dendritic Cell Maturation
Authors: Spidale Nicholas A. , Wang Bo , Tisch Roland
Published: June 2014

Thymic dendritic cells (DC) mediate self-tolerance by presenting self-peptides to and depleting autoreactive thymocytes. Despite a significant role in negative selection, the events regulating thymic DC maturation and function under steady-state conditions are poorly understood. We report that cross-talk with thymocytes regulates thymic conventional DC (cDC) numbers, phenotype, and function. In mice lacking TCR-expressing thymocytes, thymic cDC were reduced and exhibited a less mature phenotype. Furthermore, thymic cDC in TCR-transgenic mice lacking cognate Ag expression in the thymus were also immature; notably, however, thymic cDC maturation was re-established by an Ag-specific cognate interaction with CD4+ or CD8+ single-positive thymocytes (SP). Blockade of CD40L during Ag-specific interactions with CD4 SP, but not CD8 SP, limited the effect on cDC maturation. Together, these novel findings demonstrate that homeostatic maturation and function of thymic cDC are regulated by feedback delivered by CD4 SP and CD8 SP via distinct mechanisms during a cognate Ag–specific interaction.
The dispersal of gold and related elements in till and soils at the Forest Hill Gold District, Guysborough county, Nova Scotia
Authors: Maceachern I J , Stea R R
Published: June 2014

The till stratigraphy and gold distribution (in till) at the Forest Hill Gold District was extensively studied in an pro gram designed to aid gold exploration in Nova Scotia. Trenches cut to bedrock provide a unique opportunity to study the three-dimensional
dispersal of gold from a known bedrock source. Three major surficial units characterize the study area. The oldest unit is a till (Unit I) overlain by an oxidized and cemented diamict. This sequence is overlain by Units II and III which are tills characterized by a sandy matrix and locally derived
granitic and metasedi­mentary clasts. Unit II is compact and rests upon bedrock with southeastward-trending striations. Unit III is less compact and locally has a strong fabric indicating a southwest­ward ice movement. The se tills are commonly separated by a reddish-brown alteration zone
interpreted as a paleosol. A poor correlation between the panning results and the geochemical data for gold was attributed to the nugget effect. It was concluded that both panning and geochemical exploration techniques should be used in gold exploration programs in Nova Scotia. The coarse fraction
(1-2 mm) of the tills directly reflects the elemental ratios and abundances inherent to the bedrock. However, the fine fraction (<0.063 mm) of the tills shows evidence of a hydromorphic redistribution of elements. This implies that the tills at Forest Hill .are at least partially altered
by post-depositional chemical processes. The dispersal of gold at Forest Hill rejects mechanical dispersal by a major southeast­ward ice advance. The gold dispersal trains are three-dimensional bodies which come to the surface 200 to 300 m down-ice from gold-bearing veins. Gold in the till occurs as
flakes and nuggets. The surfaces of the se particles appear rough and pitted and exhibit Little evidence of abrasive glacial transport.
p-adic and Motivic Measure on Artin n-stacks
Authors: Balwe Chetan
Published: June 2014

We define a notion of p-adic measure on Artin n-stacks that are of strongly finite type over the ring of p-adic integers. p-adic measure on schemes can be evaluated by counting points on the reduction of the scheme modulo pn. We show that an analogous construction works in the case of Artin stacks as well if we count the points using the counting measure defined by Toën. As a consequence, we obtain the result that the Poincaré and Serre series of such stacks are rational functions, thus extending Denef's result for varieties. Finally, using motivic integration we show that as p varies, the rationality of the Serre series of an Artin stack defined over the integers is uniform with respect to p.
Modeling the evolution of aerosol particles in a ship plume using PartMC-MOSAIC
Authors: Tian J. , Riemer N. , West M. , Pfaffenberger L. , Schlager H. , Petzold A.
Published: June 2014

Abstract. This study investigates the evolution of ship-emitted aerosol particles using the stochastic particle-resolved model PartMC-MOSAIC (Particle Monte Carlo model-Model for Simulating Aerosol Interactions and Chemistry). Comparisons of our results with observations from the QUANTIFY (Quantifying the Climate Impact of Global and European Transport Systems) study in 2007 in the English Channel and the Gulf of Biscay showed that the model was able to reproduce the observed evolution of total number concentration and the vanishing of the nucleation mode consisting of sulfate particles. Further process analysis revealed that during the first hour after emission, dilution reduced the total number concentration by four orders of magnitude, while coagulation reduced it by an additional order of magnitude. Neglecting coagulation resulted in an overprediction of more than one order of magnitude in the number concentration of particles smaller than 40 nm at a plume age of 100 s. Coagulation also significantly altered the mixing state of the particles, leading to a continuum of internal mixtures of sulfate and black carbon. The impact on cloud condensation nuclei (CCN) concentrations depended on the supersaturation threshold S at which CCN activity was evaluated. For the base case conditions, characterized by a low formation rate of secondary aerosol species, neglecting coagulation, but simulating condensation, led to an underestimation of CCN concentrations of about 37% for S = 0.3% at the end of the 14-h simulation. In contrast, for supersaturations higher than 0.7%, neglecting coagulation resulted in an overestimation of CCN concentration, about 75% for S = 1%. For S lower than 0.2% the differences between simulations including coagulation and neglecting coagulation were negligible. Neglecting condensation, but simulating coagulation did not impact the CCN concentrations below 0.2% and resulted in an underestimation of CCN concentrations for larger supersaturations, e.g., 18% for S = 0.6%. We also explored the role of nucleation for the CCN concentrations in the ship plume. For the base case the impact of nucleation on CCN concentrations was limited, but for a sensitivity case with higher formation rates of secondary aerosol over several hours, the CCN concentrations increased by an order of magnitude for supersaturation thresholds above 0.3%.