bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk Based Internal Corrosion Assessment of Pipe in Pipe Flowline
Authors: Hogelin P. T. , Webb J. T. , Ruocco Y. , Vadel D. , Hill R.
Published: April 2018

Safety and protection of the environment are paramount to successful, effective operations. A prominent challenge in the offshore oil and gas industry is striking a balance between maximizing production from a field and managing risks to meet or exceed regulatory compliance and safety goals. Noble Energy currently manages integrity of its Gulf of Mexico deepwater assets through implementation of a riskbased integrity management (IM) program. The objective of this paper is to demonstrate the value of a risk-based assessment process to mitigate internal corrosion of a pipe-in-pipe (PIP) flowline by progressively advancing detailed engineering assessments from routine monitoring activities. The results improved understanding of internal corrosion degradation mechanism and allowed for an update to the IM plan for remaining service life.

As part of Noble Energy's subsea IM program, annual asset risk assessments are conducted to identify, assess and control operational risks. Key performance indicators (KPIs) have been implemented to manage degradation mechanisms during design review and flag potentially unfavorable operational conditions. The exceedance of a KPI limit and the reliability of monitoring data directly affect the predictability of the associated degradation mechanisms. Elevated corrosion rates from a conservative corrosion model, combined with discrepancies in topsides corrosion coupon sampling, resulted in lower confidence for threat predictability. This prompted a more detailed assessment to confirm integrity of the flowline. The assessment included a review of design and historical monitoring data. A complete produced water analysis was executed to update the corrosion model. A flow regime analysis was conducted to assess the pipeline water-wet condition and water hold-up potential for current operational conditions.

This paper presents challenges and assumptions in identifying representative load cases from a 10-year operational history. The result of the assessment was the identification of areas along the flowline with medium to high water-wetting probability, and understanding of the hazards associated with internal corrosion at the identified locations. This study provided significant improvement in visibility of the internal corrosion degradation mechanism of the flowline and develop continued risk management strategy.

This paper presents a holistic approach to managing internal corrosion threats for subsea flowlines. It demonstrates the value of linking data to degradation mechanisms to improve understanding of risks on the assets, and the value of a structured program to ensure informed and confident decisions can be made by an operator.
Application of Wear-Resistant Elastomer to Significantly Improve Service Life of Telescopic Joint Packers
Authors: Denison C. R. , Fiore C. J. , Krakowski F. J.
Published: April 2018

Advancements in elastomer technology have enabled an increased reliability and longevity of elastomeric packers used in telescopic joints. This paper provides an overview of a new nitrile and its benefits, including improved uptime for telescopic joints, achieved by prolonging seal life while maintaining actuation pressures similar to standard nitriles.

Elastomer specimens of several nitrile and polyurethane variants were subjected to rotary platform abrasion testing per ASTM D3389. This test measures the mass lost by a specimen as it wears against a rotating abrasive wheel. These same materials were subjected to ASTM D471 standard test method for liquid effects on rubber, using water as the test fluid to evaluate their propensity to swell. Telescopic joint packers manufactured from two of these compounds were subjected to full-scale laboratory comparative testing using a modified API 16F wear test. The packers were finally installed on offshore rigs to confirm the laboratory results in an operational setting.

Until recently, the industry has primarily employed standard nitriles or urethanes as dynamic seals in abrasive drilling applications. Standard nitriles often wear quickly in high-friction applications, leading to inefficient downtime to replace seals when a leak develops. Urethanes provide improved wear-resistance compared to standard nitriles, yet they are typically stiffer than nitriles and therefore require much higher actuation pressures. Wear-resistant nitriles circumvent this compromise by offering long service life without requiring changes to operating procedures. Recent advances have resulted in the growth and acceptance of wear-resistant nitriles as a solution to the market need for improved seal durability. The wear-resistant elastomer specimens demonstrated improved performance in standard laboratory abrasion tests, losing significantly less mass than standard nitriles. This durability improvement has been confirmed through full-scale product testing in the laboratory, as well as through field testing of seals manufactured from the wear-resistant elastomer compound. Results will be provided for two seals that were tested for six months on floating drilling rigs in Brazil and the North Sea.
OPEX Savings in Pipeline Blockage Remediation - Lessons Learnt from West Africa Experience
Authors: Bukkaraju Sampath K. , Osorio Nelson F. , Monge Juan I. , Estevez Gabriel J.
Published: April 2018

The primary objectives of this paper are as follows:

To share the lessons learnt from a recent blockage remediation experience offshore West Africa. To highlight the importance of sound engineering assessment in locating and identifying the nature of blockage and in the selection of appropriate blockage remediation technology. To present the methodology applied which minimized the need for costly rental equipment which in turn resulted in significant OPEX savings and minimal impact to production.

The approach taken to remediate blockages is usually driven by the cost and time required, customer preference and remediation goals (i.e., establishing communication and flow Vs. full clean out), impact to production, operating conditions, production chemistry of the produced fluids and injected chemicals, geographical location of the field, field layout, available facilities, operating history and availability and access to specialized equipment and skilled personnel. If not properly assessed and planned, blockage remediation costs can easily go out of control with no guarantee for success and a long term solution. To minimize the required resources and maximize the chances for successful blockage remediation, a structured path needs to be developed.

This paper presents and highlights the importance of accurate produced fluid sample data, information on injected chemicals and production history to determine efficiently the nature and location of the blockage. Review of the pressure and temperature sensors data at key locations along the flowpath and a good understanding of the early blockage remediation attempts and their outcomes help are key inputs to the engineering assessment of the blockage. This paper shows how the right interpretations of the sensor data prior to and during remediation of the blockage are essential part of a sound engineering assessment. The assessment followed by the selection of suitable remediation options led to the successful remediation of the blockage. The options selected were those that could be readily implemented requiring no specialized or additional equipment, avoiding alternatives that involved considerable cost and time for deployment.
Autonomy Applied to Seep Hunting for De-Risking Exploration
Authors: Lindsø Steffan
Published: April 2018

By finding and evaluating seabed seepage of oil and gas, geologists can make better decisions about drilling expensive exploratory wells. However, current seep hunting methods are costly and time consuming, and provide inconsistent results. This paper presents a concept for a new seep hunting method that uses systems comprised of existing autonomous technologies, advanced sensors, and remote piloting technologies. By using technologies developed in the oil and gas industry and other sectors, the concept has the potential to completely change the way that seepages are found and analyzed.

The current, prevailing method for seep hunting requires multiple steps, first using autonomous underwater vehicles (AUVs) to survey the seabed, followed by deployment of large manned service vessels and remotely operated vehicles (ROVs). In contrast, the new approach can discover and analyze seepages in one mobilization, without any need for personnel offshore. The system uses autonomy to deploy surface and underwater vehicles to the site and find seepages, and utilizes remote piloting technology for close-up analysis of the seepage—effectively bringing shore-based geologists to the location of the seepage.

During the past decades, the oil and gas industry has applied a range of new technologies to solve subsea engineering problems, largely for installation and maintenance of offshore infrastructure. These technologies include multi-beam sonar, ROVs, autonomous pipeline inspection vehicle sensors, and satellite communication networks. In addition, research for sensing and analyzing chemicals has pushed subsea sensor technology far beyond what was possible a few years ago.

Many of these new technologies can be combined into completely new ways of exploring for seepages to provide additional data to geologists and reduce the risk of drilling an unsuccessful exploratory well. The new method will be smarter, less expensive, and capable of covering much larger areas of the seabed than current seep hunting techniques. Most importantly, they will offer the geologist the ability to stand onshore behind the ROV pilot and explore the seabed in real time.
Managing Marine Risks to Offshore Oil Structures: How Close is Too Close?
Authors: Tieman Jason
Published: April 2018

Vessels are a critical part of offshore drilling and production operations, but they also pose a major risk to an organization's operations and to other nearby infrastructure. In some regions, vessels can also represent significant security risks. It is necessary to identify and prioritize the greatest operational risks that vessels can pose, along with their associated safety, security, and financial impacts. One of the first steps to take when trying to understand the risks associated with vessel movements is to use the same Automatic Identification System (AIS) data that has been used during the past decade to monitor vessel activities for logistical and safety purposes. Combining AIS data with radar and other input gives operators the information they need to detect, assess, and mitigate threats to offshore infrastructure before an incident can occur.

This new way to manage and mitigate risks overcomes the problems with earlier approaches (such as simply setting a radar "guard ring") and creates the opportunity for innovative new capabilities, such as establishing remote watch teams that have a consolidated view of all assets anywhere in the world. By performing watch activities, and collaboratively using a web-based platform, a centralized team can monitor and respond to risks identified across multiple global assets, ensure standardized compliance, and facilitate key performance indicator (KPI) measurements for marine risk management. Operators can also gain new insight into logistical challenges and contractor performance.
Construction Challenges in Future Offshore Wind Developments
Authors: MacLeay A. , den Hollander R.
Published: April 2018

Offshore wind is now a well-established technology in Europe with 12,631MW installed capacity from 3,589 grid connected wind turbines in 10 countries. The technology is now expanding in to new markets in North America and the Far East.

This growth is being fuelled by the reducing cost of offshore wind generation with the first subsidy free projects now in development in Europe. In these markets offshore wind will be a lower cost and more environmentally friendly means of generating electricity than gas.

This cost reduction has been driven by a number of factors but three important ones are discussed here together with a number of lessons learned from recent projects.

The wind turbines are steadily getting bigger. Larger turbines mean that fewer need to be installed for a given project size. The average size of a grid connected turbine in 2016 was 4.8MW but the future subsidy free projects will require turbines closer to 15MW. This means larger foundations and heavier turbine components need to be installed.

There is a significant degree of standardisation and repetition in the installation of offshore wind. High levels of repetition mean that a greater investment can be made on installation techniques, installation aids and procedures than would normally be seen on a one off project. This in turn places a higher demand on production and installation engineering than experienced on oil and gas projects.

The cost of project finance has come down significantly. These projects are very large and most Utilities will no longer finance them off balance sheet. Therefore the bankability of projects is critical to the developer in reaching financial close.

Based on recent successful project delivery there is a broad range of investors willing to provide finance. However, the financiers and their technical advisors set the risk levels, contracting strategy and very often the construction methodology.

Trends in offshore wind projects and lessons learned from recent projects are discussed.
A Universal Field Development Approach for Advancing Stalled GOM Deepwater Projects
Authors: D'Souza Richard , Basu Shiladitya , Khurana Sandeep
Published: April 2018

Following the oil price collapse in mid-2014, the number of deepwater projects with a floating production host platform sanctioned in the GOM plunged to historic lows. In this period only three projects were sanctioned, Stampede (2014), Appomattox (2015) and Mad Dog 2 (2017). During this time cost compression across the industry reduced the average breakeven project costs from $70 per barrel to $45-$50 per barrel for many, but not all deepwater projects. An additional 10%-15% reduction in breakeven costs is required to get these stalled projects to a final investment decision.

The industry is assessing and implementing many different strategies to achieve these additional cost efficiencies that include standardization, simplification, technology, collaboration and creative financing. Many of these are being addressed at a component level rather than at a field development level. A universal field development approach for deepwater GOM projects requiring a host platform is proposed that entails using the same building blocks for a majority of field developments that will:

Provide a universal field development solution that accommodates a range of reservoir types, sizes and complexities Maximize flexibility for field layout, phased development and contracting options Reduce project delivery uncertainty, as universality facilitates standardization and repeatability Significantly improve discovery to First Oil cycle time while adapting to changing reservoir information during the development phases

This paper presents a universal field development approach together with specific standardization and simplification recommendations of its key component building blocks; floating host platform and subsea system. Taken together these will provide the additional break even cost reduction, project cycle time improvement and increased certainty of project delivery to enable operators’ to confidently sanction a greater number of stranded deepwater Gulf of Mexico projects than is currently possible.
Virtualization: An Innovative Way to Reducing CAPEX and OPEX for Control Systems
Authors: Memuletiwon D. T. , Zimughan J. T. , Etukudoh B. I. , Olami O. , Ntemuse J. S. , Roberts E. N. , Oranye I. C.
Published: April 2018

Typical Control and Automation Systems for Oil and Gas Production Facilities consists of a large footprint of physical computer systems deployed as Workstations, Servers and HMI's (Human Machine Interfaces). Managing these systems however, can be expensive and time consuming. Given the relatively short lifecycles, frequent upgrades are required with associated plant downtime and significant CAPEX (Capital Expenditure) and OPEX (Operational Expenditure). Therefore, there is a need to maximize availability of the Control and Automation System installed base, throughout the life of the production facility by way of adopting novel technology as a key differentiator.

Virtualization is a Technology that decouples hardware and software. It allows installation of multiple operating systems that can be run as virtual machines using shared resources (Hard disk, Processors, Network Cards etc) from the physical server. Although the concept of virtualization has been in existence in the last two decades, the growing synergy between IT (Information Technology) and Industrial Automation unlocks a new platform to deploy this technology in a way that can radically change the way Process Automation networks are designed and implemented leading to simpler, more cost effective & scalable networks. The underlying concept is to improve design efficiency with minimum Physical Servers/Workstations by way of running multiple servers on a single physical machine, and in more advance deployments, collocating servers from multiple facilities to the back-end office or at a 3rd party datacenter. Currently virtualization is in use in most office domains for business applications (such as ERP) but this novel approach would focus on adopting this technology as a key differentiator in the Process Control Domain (PCD). This paper presents an overview of Virtualization, as a Control Systems solution and how it contributes to OPEX and CAPEX reduction for production facilities operations.
Compact Modular Manifold Design for Reduced Cost and Added Value Subsea Production Systems
Authors: McWilliams R. S. , Phipps P. J. , Myres D. J. , Erickson M. R. , Morrison D. S.
Published: April 2018

The focus of this paper is to present and discuss the key attributes of a cluster-type compact modular manifold (cluster type) design using new and innovative methods to integrate existing technologies in a drive to cut CAPEX, OPEX and delivery time.

A subsea production manifold plays a central role in the gathering and distribution of production fluids from multiple wells through adjoining rigid or flexible flowlines. Current market trends emphasize is towards standard products in a drive to reduce project risk, delivery and cost. Standardization of the integral components of a manifold can be easily achieved, but it is typical for the manifold package to vary depending project specific requirements. For the majority, standardization will typically mean utilizing an existing design from previous projects, which can lead to redundancies and inefficient design. By looking at a standard modular solution from the outset, a tailored type solution can be effected within a standard format. Thus, the most cost effective ‘fit for purpose’ solution for each project can be designed and delivered as standard product.

The approach to generating a modular manifold in standard design format was to take the best in class methods for discrete component manufacture and marry them to similarly designed parts that are scalable both up and down. This evolved into a design which incorporates forged headers with integrated valve blocks and compact horizontal connectors. The resulting compact, cost effective solution that can be delivered in multiple configurations using modular subassemblies. By utilizing this simple design philosophy, a reduction in size and weight compared to a typical conventional manifold can be as much as 50%. Because the modules are "standard parts", there are direct cost and lead time savings that can be passed on to the end user.

The significant reduction in size and weight greatly benefits the installation program by allowing better utilization of rear deck space during loadout. This also has a reduction in crane capacity requirement which is a significant logistical factor in deep and ultra-deep waters. By designing a lighter structure, it is possible in many cases to utilize mud mats instead of more robust suction piles, which have significant associated manufacturing and installation costs. The commercial impacts of the modular design have also been considered. Schedule risk is vastly reduced as a result of removing the majority of pressure containing welds, a process which requires elevated control to ensure correct execution. The bolted arrangement also facilitates compliance with local content requirements. Pressure containing parts and parts with critical functionality can be manufactured and tested in an environment controlled by the design authority. Parts can then be packaged and shipped for in-country assembly and SIT allowing significant in-country content with a high degree of integrity.
Development of Approval Procedures for the Land Transport of Equipment on Public Roadways
Authors: Saaijenga D. , Ekici D. , Herrington P. , Roberts M.
Published: April 2018

The offshore energy industry continues to grow worldwide into new frontiers using larger than ever, marine equipment. Much of this equipment is infrastructure fabricated at yards located inland from traditional marine terminals which then requires specialized road transports to be used. Concurrently, Marine Assurance agencies are being called upon to act as the verification agency for these transports with one of their primary goals being to ensure the safe transport of the equipment.

Despite the relatively high number of marine equipment public road transports, the importance of robust securing of cargo is often underestimated in the industry. Additionally, the required operational Quality Assurance/ Quality Control (QAQC) procedures to be applied for a successful and safe operation are often disregarded. One of the main contributors to these issues is the lack of common guidelines recognized across the industry. The correct understanding of the requirements for the road transport will permit reliable and cost-effective operations to be performed in a timely manner.
Formation and Development of Seabed Trenching from Subsea Inspection Data of Deepwater Gulf of Guinea Moorings
Authors: Colliat Jean-Louis , Safinus Stefanus , Boylan Noel , Schroeder Knut
Published: April 2018

It is now recognized that seabed trenching in taut deep water moorings can reach the suction anchor and the chain padeye depth, with the safety of the mooring system becoming a concern. However, the actual formation of such trenches and their development with time are still largely unknown, as well as the relation with the characteristics and dynamics of the mooring systems. The analysis of a database of subsea inspection data from deep water Gulf of Guinea mooring systems is presented. The trench data, from in-service subsea inspections of mooring systems for five FPSO vessels and off-loading terminal buoys, comprise the measurement of trenches width and depth and of anchor-to-trench distances. Because similar metocean and soil conditions apply to the ten mooring systems, the study offers a unique database for better understanding the formation and evolution of this seabed trenching. The subsea inspections were carried out between 2014 and 2017 but the study covers a much larger time span of moorings performance as the FPSOs and off-loading buoys were installed between 17 years and 5 years ago. The trench development is studied in relation with the moorings characteristics and dynamics and is illustrated with typical features and trench geometries for the two types of floaters. The results obtained represent a key improvement for understanding this seabed trenching phenomenon and are most probably applicable to all deep water moorings of the Gulf of Guinea area. Preliminary recommendations about design aspects and possible mitigations that can be considered for limiting the seabed trenching are also addressed in the paper.
First Set of Bulk Standard Specifications Set to Reduce Cost and Delays in Offshore Oil & Gas Projects
Authors: Ellingsen H. P. , Lim Y. K. , Shin H. C. , Singh K. , Kang S. Y. , Kim Y. H. , Cho S. , Ok D.
Published: April 2018

This paper describes measures to reduce the cost and delay of large offshore projects by use of new standard specifications for bulk items developed through a Joint Industry Project (JIP) initiated in 2015. The JIP has established several new standards specifications for structure, piping and Electrical and Instrumentation (E&I) with broad participation from fabricators, class societies, operators and engineering companies. The main objective of the JIP has been to reduce cost and increase predictability without compromising quality and safety by adopting industrial agreed standard components and equipment as well as procedures.

This paper outlines examples how and why the new standard specifications will reduce Capital Expenditure (CAPEX) and delay related to bulk items and the process applied in the JIP of aligning different standards and project specifications. A gap analysis method was applied to compare overlap and differences amongst standards and criteria for selection of standards were defined to select the most appropriate requirements and specifications. Business case templates have been established, documenting many examples causing delays and misunderstandings which would be addressed and eliminated through application of the new standard specifications.

The results cover the most common bulk items such as structural steel, outfitting, piping, cables, cable trays, instrument tubing, piping insulation and monorails. In some cases, the standard specifications bridge the gaps between existing international standards such as from International Organization for Standardization (ISO) and The American Petroleum Institute (API). In other cases, new requirements and specifications fill gaps in areas with lack of details in international standards or where no international standards and codes exists. The bulk standards will remove obstacles and streamline the fabrication process to the benefit for all stakeholders in engineering, procurement and construction. Although the new standard specifications are considered a quick win to save cost on bulk items in the short term, long term efforts are required to bring alignment amongst international standards such as ISO and API.

Following the design and material standardization, the next major step to be taken by the JIP and the industry is to create common coding and data formats of design and material. This step has the potential to make a big impact for CAPEX reduction and reduced time to first oil by creating a seamless interface between engineering and fabrication.
Large Umbilical Multibore Installation
Authors: Noone Richard
Published: April 2018

The Vashishta and S1 fields development located on the east coast of India included a main umbilical of 183mm (7.2in) installed between the onshore terminal and the S1 Subsea Distribution Unit (SDU). The main umbilical consisted of three segments; a 3.3km (2mile) onshore terminal to land fall point umbilical, a 26.4km (16.4mile) land fall point to lower multi-bore umbilical, and a 4.8km (3miles) upper multibore to the Umbilical Termination Distribution Assembly (UTDA) umbilical in approximately 280m (918ft) water depth. The main umbilical included 28 hydraulic lines, six electricals cables, and six fiber optic lines. The multibore design was required to be large enough to accommodate all the umbilical components but compact enough to install.

The installation of the 26.4km (16.4mile) umbilical required a beach pull and the lower multibore was wet stored. The installation of the 4.8km (3mile) umbilical involved the retrieval of the lower multibore, mating the lower and upper multibores, and landing the UTDA on a pre-installed mounting base. A multibore was added between the land fall point to the S1 SDU main umbilical to allow two separate vessels to perform the installation. One vessel was for the beach pull and shallow water section of the umbilical, and a second was for the deep section and UTDA landing. The beach pull and laydown of the lower multibore was performed by the McDermott Derrick Barge 30 (DB30). The lower multibore retrieval, mating, testing and installation was carried out by the McDermott Lay Vessel North Ocean 102 (NO102).

The multibore solution is not a novelty for umbilical connection; however, due to the size of the umbilical and quantity of lines, this was a project specific developed solution with significant challenges in terms of testing and installation.

The purpose of this paper is to describe the factors involved in the decision making process to add a multibore connector to the main umbilical. Also, to present the challenges associated with the different phases of its development, from initial conception to final mating, testing, overboarding and landing on the seabed.
The End of Cool Down Testing
Authors: Alfredsson Henrik , Rolland Julien
Published: April 2018

Cool Down Testing (CDT) used to be an integral part of project execution justified in order to verify the thermal performance of an insulated subsea production system. To combat cost and schedule risk a joint venture set out to qualify Computational Fluid Dynamics (CFD) methods to fully predict the thermal performance of any insulated subsea component and/or system without the need for future CDTs. This paper outlines the results from that work where CDT data compared to simulation results prove predictability within 1 °C accuracy for the subsea system product range.

Results from simulations and full scale cool down tests on Kaombo Subsea Production System (SPS) reveal the importance of a system approach where interaction between components enables a system including thermal weak links to adhere to some of the most extreme thermal requirements seen in subsea development to date. Utilizing this approach the thermal system can be wisely managed retaining heat where available and allowing for local cold spots which, treated individually, would never meet the thermal requirement. The CFD tool enables the system provider to predictively size the insulation for the whole SPS without the need for future cool down testing. The predictive CFD tool furthermore enables a reduced execution cost and schedule risk by cutting out future cool down testing. This is especially important for small to medium sized brown field developments where cool down test avoidance constitutes considerable savings in the SPS budget. Avoiding late project findings and insulation system over-sizing to combat uncertainties also help to considerably drive down execution cost and risk for insulated subsea production systems.
HPHT Materials - Push the Limit with Standardization and Innovation
Authors: Tang Fei , Viteri Martha , Thodla Ramgopal
Published: April 2018

High pressure high temperature (HPHT) technology and field development have received much attention in recent years. Materials for HPHT environments, including ultra-high strength alloys and soft polymer compounds will in some cases be close to their capability limits. Materials testing and qualification have therefore been challenging for HPHT equipment design and project execution. At the same time, lower oil prices have put cost pressures on project developments. To overcome both technical and financial challenges while ensuring satisfactory project safety and performance, holistic and systematic solutions promoting materials standardization and innovation are necessary. In this paper, case studies and lessons learned from several recent and widely recognized Joint Industry Projects on subsea materials are presented. The philosophy of materials standardization and innovation behind these efforts will be discussed and their positive impacts on HPHT materials qualification and testing will be summarized.
Solutions to Some Mysterious SCR Hydrodynamic Behaviors and their Applications for Improved SCR Design
Authors: Yue B.
Published: April 2018

Steel Catenary Riser (SCR) is the most cost effective option for numerous deep water field developments. Despite its structural simplicity, the design and analysis of SCR's can be complex especially due to the hydrodynamic forces. This paper selects three of the unexplained observations in SCR analyses, solves the mysteries analytically, and provides recommendations accordingly for improving riser design.

The three selected observations that are not well understood occur at three distinct locations along the SCR: the hang-off, the middle section, and the Touch Down Zone (TDZ). The riser maximum stress at the hang-off can be lower when the wave particle motion is considered in the dynamic simulation compared with using vessel motion time trace only. The TDZ fatigue damage is observed to be lower when background current is applied along riser in the motion fatigue analysis, even if the current direction is perpendicular to the riser motion direction. Finally, the motion fatigue response is observed to be better with a shorter strake length compared with that of the configuration wherein the strake coverage is extended to the seabed.

The first two phenomena are generally explained by the "damping" effect, however, how the damping works was never clearly demonstrated. The third observation is actually contradictive to the damping effect as less strake length results in smaller drag forces and thus less damping. All of the above phenomena are related to the hydrodynamic forces that are exerted onto the riser by the surrounding sea water. Those forces are calculated by Morison's equation which includes drag force and inertia forces. In this paper, a detailed analytical study using Morison's equation illustrates how the drag force or inertia forces will affect the riser motion, and which force is the dominating one, for each of the three observations aforementioned.

The understanding of these riser hydrodynamic behaviors leads to improved riser design. The applications of wave hydrodynamics and background currents present more realistic riser responses and reduce conservatism and thus cost. A riser with shorter strake length but more fatigue life will result in reduced cost too provided that adequate VIV fatigue life is preserved.
The Planning and Execution of the Tortue High Rate Gas Well DST in Offshore Deep Water Mauritania
Authors: Vu Hiep S. , Guerra Mike D. , Berry Paul A.
Published: April 2018

The Greater Tortue Ahmeyim (GTA) field offshore Mauritania and Senegal is a large, deep-water gas complex with two main reservoir sequences, the Lower Cenomanian and the Albian. The area was discovered by Kosmos Energy (Kosmos) in April 2015 by the Tortue-1 discovery well. Kosmos has since successfully confirmed three major fairways of the Senegal River Trend within the broader Mauritania and Senegal basin with the Guembeul-1A, Marsouin-1, Ahmeyim-2, Teranga-1, and Yakaar-1 wells. The outboard Cretaceous petroleum system offshore Mauritania and Senegal is potentially one of the largest petroleum systems ever opened along the Atlantic Margin.

Kosmos entered into a joint venture partnership with BP in respect of its interests in Mauritania and Senegal in December 2016. Dynamic production data was desired to further appraise the Lower Cenomanian reservoirs. A fast-track Drill Stem Test (DST) was conceived, planned, and conducted on the Tortue-1 discovery well beginning in June 2017 to assist in validating reservoir connectivity, productivity, original gas-in-place, and fluid quality. The DST, operated by Kosmos on behalf of the partnership, targeted two distinct reservoirs within the Lower Cenomanian sequence. The key information extracted from the well test has been used to support the Front End Engineering Design (FEED) currently underway, with a corresponding Final Investment Decision (FID) planned in late 2018.

This paper presents the objectives and design methodology, as well as the technical and operational challenges while conducting a dual-zone, high rate gas well test in ultra deep water within a compressed time schedule. This paper also presents the technology that Kosmos and BP selected to isolate the test intervals and gather pressure and temperature data during the extended flowing and buildup periods.

Finally, the key results of the DST are highlighted that underpin the development concept for the Tortue field.
Overview of the Malikai Project
Authors: Adrian E. , Wong S. H.
Published: April 2018

By all accounts, Malikai is a marginal field – limited reserves in challenging reservoirs, remote from existing infrastructure and in 500m water depth. The field was discovered in 2004 and initial concepts based on a standalone development were not economically viable.

The fact that it is now a producing asset is a success story built on effective collaboration, innovation and discipline execution. Shell with its JV partners (Conoco Philips, PETRONAS Carigali) reviewed the original field development and made the key decision to have Malikai as a satellite development to their Kebabangan production hub. To further reduce capital investment, the project team had to look at fit-for-purpose technical solutions (e.g. use of single casing combo top tensioned risers, tender assisted drilling). The tendering strategy allowed for maximum input from the industry while maintaining a design that remains compliant to Shell's proven deepwater design guidelines. It goes without saying that staying to cost and schedule promises took on a much heavier emphasis. Management of Change was strictly enforced. Similarly, with contract management. Key resources from Shell's center of excellence in Gulf of Mexico were mobilised to lead and deliver key components (tendons, risers). Others were on hand to provide advice and technical assurance on critical activities (integration, offshore installation, etc.). Local content and technology transfer were always important differentiators to Shell's operating model in Malaysia. This is clearly demonstrated in the make-up of the project team including its leadership. Goal Zero is a watch word especially at the main fabrication yard. The project recorded 25 million man-hours without any serious, lost-time injury and thereby keeping well below the Company's set targets.

 

 

 

 

As a result of all the efforts, Malikai registered its proud place in oil and gas records as the 1st TLP for Malaysia and Shell's 1st outside Gulf of Mexico.
Integration of Multi-Site Engineering, Procurement, Fabrication and Commissioning
Authors: Edwards S. C. , Fuller D. A. , Johnson M. K. , Nahas M. A.
Published: April 2018

In November 2017, ExxonMobil Canada Properties (EM) started production from the world-class Hebron development located approximately 340 km offshore St. John's, Newfoundland and Labrador (NL), Canada. The Hebron Platform is a standalone concrete single shaft Gravity Base Structure with an Offshore Loading System, Single Integrated Drill Rig, and Topsides production facilities capable of handling 150,000 barrels per day of crude oil.

The Hebron Project was developed from Pre-FEED to Start-Up over the course of eight years in more than a dozen work sites. The project has achieved schedule commitments and liquidated more than 60 million work hours. A large contributor to success was the effective integration and management of engineering, fabrication and commissioning organizations at all work locations. This paper will explore the execution techniques which enabled the organization to successfully manage a complex scope divided amongst diverse work locations and contractors as well as describe some of the leadership and management techniques employed to create productive work behaviors across teams and work locations.
One Gulf Reaching 50 Billion Boe and Growing
Authors: Duncan Tim , Braathen Bjørn Inge , McCormack Niall , Stauble Martin , Campbell Lorna , Cizek Mark , Rasmussen Stein , Khurana Sandeep , Wilson Julie
Published: April 2018

The Gulf of Mexico (GOM) has gone through many waves of exploration and development, each time reinventing and pushing the boundaries. Finally, the realization of crossing boundaries and combining United States and Mexico GOM into "One GOM" commercially and technically is within reach. One GOM resource base - discovered remaining to be produced and prospective - is reaching 50 billion barrels of oil equivalent (BBOE). New plays in the U.S. GOM and the opening of the Mexican GOM, coupled with innovative technological and commercial models and increasing interest from the investment community, are poised to drive value and keep this resource base and production growing further.

This manuscript sets the stage for the panel discussion scheduled for 9.30am to 12.00pm, Thursday, May 3, 2018 at the Offshore Technology Conference (OTC). The panelists are oil company executives representing small to large independents and integrated oil companies along with service providers as follows:

Tim Duncan, President and CEO, Talos Energy LLC

Bjorn Inge Braathen, SVP Exploration, Statoil

Niall McCormack, Vice President Exploration, BHP Billiton Petroleum

Martin Stauble, Vice President Exploration, Shell

Lorna Campbell, Mexico Exploration Manager, ExxonMobil

Mark Cizek, Vice President, Williams

Stein Rasmussen, Chief Strategy Officer, SBM Offshore

Sandeep Khurana, Sr. Manager, Granherne (A KBR Company) and

Julie Wilson, Director, Wood Mackenzie
The reformation of space for public worship: Past and present – Continuing the discussion
Authors: Whytock Jack C.
Published: April 2018

In the light of the 500th anniversary of the Reformation, this article will explore a neglected area of Reformation studies namely the reformation of space for public worship in the past and the present. The article has three parts: first, a general survey of worship space at the eve of the Reformation; second, the response of the Magisterial Reformers (with a focus upon those who would be classified as reformed) to the space for public worship by principle and actuality; and third, the ongoing use of space for public worship chiefly in the evangelical and reformed tradition. On this final point specific examples will be included concerning public worship space in the contemporary context. The article is an introduction in what is really a broad interdisciplinary approach raising matters related to church history, theology, liturgics, aesthetics, stewardship and architectural design in a general manner and will make suggestions for further ongoing discussion. This article endeavours to help by providing an historical context for further discussion of the subject matter of the use of space in public worship and it is hoped that further articles will follow from this introduction to the subject.
О поведении степенных рядов с вполне мультипликативными коэффициентами вблизи единичной окружности
Authors: Petruschov Oleg Alekseevich
Published: April 2018

В данной статье исследуются степенные ряды с коэффициентами -
значениями вполне мультипликативных функций из общего класса,
определяемого небольшим количеством ограничений. В статье
доказываются асимптотические оценки при стремлении к корням
из единицы по радиусам единичной окружности
для таких степенных рядов, откуда, в частности, следует
непродолжаемость этих рядов за единичный круг.
Библиография: 13 названий.
Число помеченных внешнепланарных $k$-циклических графов
Authors: Voblyi Vitalii Antonievich
Published: April 2018

$k$-Циклический граф - это граф с цикломатическим
числом, равным $k$. Получена явная формула для числа помеченных
связных внешнепланарных $k$-циклических графов с заданным числом
вершин. Кроме того, такие графы с фиксированным числом $k$ и большим
числом вершин перечислены асимптотически. Как следствие, выводится,
что при фиксированном числе $k$ почти все помеченные связные
внешнепланарные $k$-циклические графы с большим
числом вершин являются кактусами.
Библиография: 12 названий.
Дистанционно регулярные графы Шилла с $b_2=c_2$
Authors: Makhnev Aleksandr Alekseevich , Nirova Marina Sefovna
Published: April 2018

Графом Шилла называется дистанционно регулярный граф диаметра 3
со вторым собственным значением $\theta_1$, равным $a_3$.
Для графа Шилла положим $a=a_3$ и $b=k/a$. В работе доказано,
что граф Шилла с $b_2=c_2$ и нецелым собственным значением имеет
массив пересечений
$$
\{\frac{b^2(b-1)}2,
\frac{(b-1)(b^2-b+2)}2,
\frac{b(b-1)}4;1,
\frac{b(b-1)}4,
\frac{b(b-1)^2}2\}.
$$
Если $\Gamma$ является $Q$-полиномиальным графом Шилла с $b_2=c_2$,
то в случае $b=2r$ граф $\Gamma$ имеет массив пересечений
$$
\{2rt(2r+1),(2r-1)(2rt+t+1),r(r+t);1,r(r+t),t(4r^2-1)\}
$$
и для любой вершины $u$ из $\Gamma$ подграф $\Gamma_3(u)$ является
антиподальным дистанционно регулярным графом с массивом пересечений
$$
\{t(2r+1),(2r-1)(t+1),1;1,t+1,t(2r+1)\}.
$$
В работе классифицированы
также графы Шилла с $b_2=c_2$ и $b=4$.
Библиография: 7 названий.
Экспоненциальная устойчивость одной полугруппы и приложения
Authors: Zakora Dmitry Aleksandrovich
Published: April 2018

Доказывается равномерная экспоненциальная устойчивость
$C_0$-полугруппы с генератором специального вида.
Такие полугруппы возникают при изучении различных задач
теории вязкоупругости. Доказанное утверждение применяется
к исследованию асимптотического поведения решений в задаче
о малых движениях вязкоупругого тела
при нагрузках специального вида.
Библиография: 31 название.
Плоские разбиения и их пьедестальные многочлены
Authors: Ogievetskii Oleg Viktorovich , Shlosman Semen Bensionovich
Published: April 2018

Для линейного расширения $P$ частично упорядоченного
множества $\mathscr S$ мы рассматриваем производящий многочлен
(от многих переменных) некоторых обратных разбиений на $\mathscr S$,
называемых $P$-пьедесталами. Мы устанавливаем
замечательное свойство этого многочлена: он не зависит от выбора
порядка $P$. В случае, когда $\mathscr S$ - диаграмма Юнга, мы
показываем, что этот многочлен обобщает многочлен крюков.
Библиография: 4 названия.
Coinfection with Enteric Pathogens in East African Children with Acute Gastroenteritis—Associations and Interpretations
Authors: Andersson Maria , Kabayiza Jean-Claude , Elfving Kristina , Nilsson Staffan , Msellem Mwinyi I. , Mårtensson Andreas , Björkman Anders , Bergström Tomas , Lindh Magnus
Published: April 2018

Enteric coinfections among children in low-income countries are very common, but it is not well known if specific pathogen combinations are associated or have clinical importance. In this analysis, feces samples from children in Rwanda and Zanzibar less than 5 years of age, with (N = 994) or without (N = 324) acute diarrhea, were analyzed by real-time polymerase chain reaction targeting a wide range of pathogens. Associations were investigated by comparing co-detection and mono-detection frequencies for all pairwise pathogen combinations. More than one pathogen was detected in 840 samples (65%). A negative association (coinfections being less common than expected from probability) was observed for rotavirus in combination with Shigella, Campylobacter, or norovirus genogroup II, but only in patients, which is statistically expected for agents that independently cause diarrhea. A positive correlation was observed, in both patients and controls, between Ct (threshold cycle) values for certain virulence factor genes in enteropathogenic Escherichia coli (EPEC) (eae and bfpA) and toxin genes in enterotoxigenic E. coli (eltB and estA), allowing estimation of how often these genes were present in the same bacteria. A significant positive association in patients only was observed for Shigella and EPEC-eae, suggesting that this coinfection might interact in a manner that enhances symptoms. Although interaction between pathogens that affect symptoms is rare, this work emphasizes the importance and difference in interpretation of coinfections depending on whether they are positively or negatively associated.