bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Magnetic Resonance Imaging to Predict Quadrupled Semitendinosus Graft Diameter in All-Inside Anterior Cruciate Ligament Reconstruction
Authors: Serino Joseph , Murray Ryan , Argintar Evan H.
Published: April 2017

This study was conducted to evaluate whether preoperative magnetic resonance imaging (MRI) measurements of the cross-sectional area and length of the semitendinosus tendon correlated with graft diameter. The goal of the study was to identify tendons at risk for requiring graft augmentation. The records of 140 consecutive patients undergoing anterior cruciate ligament (ACL) reconstruction between 2013 and 2016 were examined retrospectively. The study included 39 patients who underwent all-inside ACL reconstruction with a semitendinosus autograft. A single researcher used preoperative MRI scans to measure the cross-sectional area and length of the semitendinosus tendon. Graft cross-sectional area was correlated with semitendinosus tendon cross-sectional area with Pear-son's coefficients of 0.50 (95% confidence interval [CI], 0.21–0.70;
P
=.0013) and 0.59 (95% CI, 0.34–0.76;
P
=.0001) when measured under 2× and 4× magnification, respectively. In addition, MRI measurements of semitendinosus tendon length were correlated with both intraoperatively measured tendon length (
r
=0.75; 95% CI, 0.40–0.91;
P
=.0008) and graft diameter (
r
=0.43; 95% CI, 0.14–0.66;
P
=.0058). Average semitendinosus tendon cross-sectional area was 3.10 mm
2
(95% CI, 0.53–5.67;
P
=.024) greater and semitendinosus tendon length was 14.05 mm (95% CI, 1.25–26.85;
P
=.035) greater in cases that did not require graft augmentation. Semitendinosus tendons with cross-sectional area of less than 13.2 mm
2
or length of less than 81 mm are most likely to require graft augmentation. In addition, MRI measurements of the length and cross-sectional area of the semitendinosus tendon are significantly correlated with ACL graft diameter and could help to identify patients who may require graft augmentation. [
Orthopedics.
2017; 40(4):e617–e622.]
Poor Utility of Gonadal Shielding for Pediatric Pelvic Radiographs
Authors: Lee Mark C. , Lloyd Jessica , Solomito Matthew J.
Published: April 2017

Plain pelvic radiographs are commonly used for a variety of pediatric orthopedic disorders. Lead shielding is typically placed over the gonads to minimize radiation exposure to these sensitive tissues. However, misplaced shielding can sabotage efforts to protect patients from excessive radiation exposure either by not covering radiosensitive tissues or by obscuring anatomic areas of interest, prompting repeat radiographic examinations. The goal of this study was to determine the incidence of misplaced shielding for pelvic radiographs obtained for pediatric orthopedic evaluation. Children 8 to 16 years old who had an anteroposterior or frog lateral pelvic radiograph between 2008 and 2014 were included. A total of 3400 patients met the inclusion criteria, and 84 boys and 84 girls were randomly selected for review. For both boys and girls, the percentage of incorrectly positioned or missing shields was calculated. Chi-square testing was used to compare the frequency of missing or incorrectly placed shields between sexes and age groups. Pelvic shields were misplaced in 49% of anteroposterior and 63% of frog lateral radiographs. Shielding was misplaced more frequently for girls than for boys on frog lateral radiographs (76% vs 51%;
P
<.05). Pelvic bony landmarks were often obscured by pelvic shielding, with a frequency of 7% to 43%, depending on the specific landmark. The femoral head and acetabulum were obscured by shielding in up to 2% of all images. The findings suggest that accepted pelvic shielding protocols are ineffective. Consideration should be given to alternative protocols or abandonment of this practice. [
Orthopedics.
2017; 40(4):e623–e627.]
Rethinking the ties between Brussels and its port: a development issue for the canal area
Authors: Mazy Kristel
Published: April 2017

Due to a flexible and cross-cutting approach, the urban project is emblematic of contemporary urbanistic concepts. Can this approach reconnect cities, ports and waterways? On the contrary, can it reinforce the disconnection under way, in a context in which the rationale of the market is more favourable to the sphere of residential economy than to the sphere of productive economy? This question is raised especially with respect to the canal area of Brussels, where major challenges intersect: urban densification in a context of demographic growth, the transferring of river freight as a sustainable alternative to the road network, and the improvement of water management. The aim of this article is to understand the evolution of the relationship between city and port via the interactions of the projects of the different stakeholders concerned. By means of a spatial and temporal approach, the results show that through their materialisation, the projects contribute to reproducing the functional divisions of the industrial era, caused by their economic environment. However, through their processes, new frameworks for a dialogue between city and port emerge. These observations provide some ideas for a reconnection between the city and its port.
Youth Employment
Authors: Öztürk Şenol
Published: April 2017

Youth employment has been a challenge with gradual acceleration from beginning of 1990s. It also has been exacerbated by latest global crises. Besides, as a fact mutually having a fostering relation with it, increasing rate of inactive population among the youth has caused to soar worry about the matter. Although youth unemployment is a common problem for developed and developing countries, it differs in these countries in terms of formation, intensity and solution way. In two decades countries around the world have implemented particular policies against the matter accordance to action plans prescribed by international organizations such as ILO, OECD and EU. Even though, there has been some partial improvements as a result of economic and labour market policies, there is a long way to solve the problem significantly and to decrease the anxiety down to reasonable level. Therefore, the countries must continuously monitor and analyze their conditions and create integrated policies suited to socio-economic conjuncture.
Global Governance vs. Regional Governance in Social Policy
Authors: Ünlü Adviye Damla
Published: April 2017

Globalization, the much-debated phenomenon of the last decade, has affected the governance of policies. Social policy governance is one of the most affected notions of the globalization process. Context of debates on social policy governance has been transformed from state-centric analysis to the multi-centric analysis. The future of the social policy is highly linked to both global governance and regional governance. In this regard, the aim of this chapter is to draw attention to the multi-centric nature of the social policy governance and to form a framework for the effects of intergovernmental institutions on social policy governance and to discuss their weaknesses and strengths particularly regarding the United Nations, Bretton Woods institutions and the European Union.
User Acceptance of Computer Technology at Work in Arabian Culture
Authors: Hu Han-fen , Hu Paul Jen-Hwa , Al-Gahtani Said S.
Published: April 2017

User acceptance of computer technology in work environments could differ from that of general consumer contexts. Toward that end, cultural considerations could affect individuals' behaviors, including their technology acceptance. This study analyzes the acceptance of computer technology by 1,088 workers in an Arabian country to reexamine and compare established models and theories to prior studies in the Western, developed countries. The explanatory power of each theory or model seems lower among Arabian workers. The innovation diffusion theory (IDT) appears capable of explaining workers' technology acceptance better than the theory of planned behavior (TPB) or technology acceptance model (TAM) does. Perceived behavioral control and subjective norms constitute more important acceptance determinants than attitude does. Both perceived usefulness and perceived ease of use remain significant determinants of attitude and intention; however, considering findings reported by previous research, their total effects are comparable in magnitude and statistical significance. The findings are incongruent with the results of several representative prior studies that examine the same theories and models. The results can be partially explained by the unique socio-cultural characteristics and overall technology development status of the country. In turn, these results offer several implications for studying worker's technology acceptance in developing countries with a unique cultural context.
An Integrated Framework via the Convergence Phenomenon for the Emergence of Software-as-a-Service
Authors: Teracino Elizabeth A. , Seo DongBack
Published: April 2017

Firms from previously distinct industries are increasingly adopting software-as-a-service (SaaS), allowing for the emergence of new markets at the convergence of these industries. The motivation for this research is to explore what is occurring as a result of the convergence phenomenon. The convergence phenomenon is when a technological evolution occurs where previously separate products or services merge into a single offering and cross-industrial collaboration increases as a result. By reviewing literature on the phenomenon in affected industries, such as the telecommunications, television and computer industries, the main aspects are identified and integrated into one framework to analyze the phenomenon as a whole. The inter-relations of the main aspects are explored through the lens of mobilization of institutional theory. The framework's applicability is then explored against a historical case. Future research suggestions are offered to further corroborate the framework to increase its generalizability for analyzing the convergence phenomenon in other relevant industries.
Factors Influencing the Success of Permission-Based E-Mail Marketing Websites
Authors: Lin Hsin-Hui , Li Hsien-Ta , Wang Yi-Shun
Published: April 2017

This research reports the development and testing of a permission-based e-mail marketing (PEM) website success model that integrated perspectives on information management/e-commerce, media/communication, and customer/marketing research. Specifically, the relationships among customer benefits, relationship quality, and relationship outcomes are examined. Data were collected from an online survey and analyzed with structural equation modeling. The results indicated that information quality benefits and ease of use benefits have positive effects on user satisfaction and user commitment and entertainment benefits positively influence user satisfaction. User satisfaction and user commitment have positive effects on user loyalty and user word of mouth. However, confidence benefits, social benefits and special treatment benefits have non-significant effects on user satisfaction, user commitment, user loyalty, and user word of mouth. It concludes that, unlike brick-and-mortar context, relational benefits emphasized by customer/marketing research do not play a significant role in influencing relationship outcomes in the context of PEM websites. Rather, functional and process benefits are important in establishing PEM website success, which supports the perspectives from information management/e-commerce research and media/communication research.
Success of National Healthcare Services Information Systems
Authors: Hung Wei-Hsi , Chang Li-Min , Lee Mei-Hui
Published: April 2017

Due to the rising awareness of national health insurance services and the wide-spread use of information systems, the implementation of National Healthcare Services Systems (NHSS) becomes an important objective to the countries in the world. However, it is not an easy task to implement such a large-scale system because we often counter a great number of managerial problems. This study identifies influential factors and constructs a model from the dimensions of user characteristics, organizational context, and system characteristics for explaining National Healthcare Services Systems (NHSS) success in Taiwan based on the survey of 1215 public healthcare workers. Several key findings have been proposed. First, eight salient factors were influential to NHSS success. Second, the NHSS is not a typical type of IS, since it is designed to provide accurate health information to support the routine NHS activities. The results demonstrate that information quality is the most critical factor in influencing system use and user satisfaction. Third, this study found that service quality has a strong and positive effect on system use and user satisfaction. Fourth, to increase system use and user satisfaction, this study suggests that the NHSS provider should communicate closely with its users to gather information about their needs and preferences, and pay more attention to each individual for providing quality service. It is hoped that the findings of current study can assist governments in other countries in developing more effective NHSS and better e-Government practices.
Non-Parametric Method for Estimating Extreme N-Year Profiles for Loop Current and Eddies
Authors: Agarwal Puneet , Forristall George
Published: April 2017

Extreme N-year current profiles for Loop Current and Eddies (LCE) are required for the strength and fatigue assessment of the risers and wellhead/casing systems. The profiles for different return periods (i.e., N = 1, 10, 100, etc.) are derived from an extreme value analysis (EVA) of the available data.

The traditional derivation of N-year profiles is based on the parametric EVA. These methods consist of fitting a parametric joint probability distribution to two or three mode amplitudes from an Empirical Orthogonal Function (EOF) analysis. The parametric method is intended for and most used when statistical extrapolation is required, i.e., the duration of available data is shorter than the desired return period. The parametric methods often require the user to make a few subjective choices relating to the distribution fitting.

In the present paper, a new non-parametric method is introduced to derive N-year current profiles from a multivariate EVA of the three EOF mode amplitudes. The method is completely objective and no subjective decisions are required. The method is applied to 1,000 years of hindcast current data that is simulated from GEM42 model for a site in the Gulf of Mexico. The current data consists of mode shapes and amplitudes of the first three empirical orthogonal functions. Profiles for return period up to 100 years are computed so the statistical extrapolation is not required.

In the non-parametric method, a peaks-over-threshold (POT) technique is first used to extract extremes of a controlling variable such as the surface current velocity or total energy of the current profile. The mode amplitudes at the time steps of those extremes are then extracted; the mode superposition relationship among the mode amplitudes is thus maintained. The set of mode amplitudes for a return period of N years is obtained from the empirical cumulative distribution function of the controlling variable, i.e., only the order statistics are utilized. The uncertainty associated with using only the order statistics is minimized by using the bootstrap technique. It is shown that N-year values thus derived are largely independent of threshold choice, which is also an advantage of this method. N-year current profiles derived from the non-parametric method are found to be similar as those derived from a parametric method; however, non-parametric estimates have the advantage of being objective.
Design of a Self-Installing Innovative Floating Platform for Wind Turbine for Deepwater Offshore USA West Coast
Authors: Srinivasan Nagan
Published: April 2017

Offshore wind farms gain momentum in the Atlantic Ocean with Jacket type of the Structures to support the wind turbines. The shallow water attracts the use of the Jacket structure piled into the seabed. The West Coast Pacific Ocean has deep water where the floating wind farms are recommended. Due to commercial and economic reasons, the offshore wind farm in the West Coast of the U. S. water has yet be initiated though it present important potential future opportunities. This paper addresses an innovative Offshore Wind Support Design with a floating vessel concept that avoids the need of the large crane supported and expensive day rate installation vessel. The specialty of this design is that it has two levels of telescopic configuration one for the floating vessel and the second for the turbine supporting tower. The installation vessel free configuration is the source of large cost reduction. The turbine is feasible to have pre-assembled, preinstalled and pre-commissioned in the controlled harbor facility on the shore before towed into the water. That increases the reliability of the system and reduces the construction time in the offshore. The most attractive result is that the capital cost per MW estimated is below the market price of the already installed and planned wind farms in the East Coast of the U. S.
Strengths and Weaknesses in the HP/HT Design Verification Process within Gulf of Mexico
Authors: Patel Harish , Ji Jing , Meruva Satya , Lin Jessie
Published: April 2017

Technology advancements applied to the design of high-pressure, high-temperature (HP/HT) equipment for offshore drilling and production during recent years has increased. Now being manufactured, installed and operated on producing wells in the Gulf of Mexico (GOM), this HP/HT equipment has enabled the development of fields that were previously considered to be unviable. Regulations require an independent third party (I3P) verification process to be conducted on HP/HT equipment. The verification process is to assure conformance with applicable industry codes and standards. The mandated verification and validation raises some questions: What can be learned by these processes? Are there opportunities for design improvements in any of the HP/HT equipment?

The industry is learning how to apply advanced analysis methods which are based on the American Society of Mechanical Engineers (ASME) Section VIII, Division 3 methods for pressure vessels. These advanced methods require detailed equipment design verification. Regulatory officials and operators alike need assurance that the technology qualification process addresses all of the appropriate failure modes. Likewise, are hazards associated with these HP/HT operations fully identified and mitigated by appropriate procedures? Are the design analyses performed accurate, complete, and do they provide a high degree of confidence for each stakeholder?

In the text of this paper, details on how the appropriate verification process is being applied to each of the various HP/HT equipment systems are discussed. The paper will detail a list of common issues that have arisen, and describe how each has been addressed. The actions being taken to assist the offshore industry with a verification process to fully comply with the intent of several applicable design codes are addressed. It will also show how the identified risks are being addressed during verification. These descriptions will assist in creating focused discussions with subsequent improvements for HP/HT environments and new, advanced technology for future HP/HT equipment being applied.

The views expressed in this paper are of the authors in their individual capacities and do not reflect the positions or opinions of the authors' employer – American Bureau of Shipping (ABS).
Low-Temperature Dispersant Improves Cement Slurry Properties in Deepwater Operations
Authors: Diarra R. , Bogaerts M. , Andrews H. , Lehr J. , Osteen N. , Cammarata R.
Published: April 2017

The cementation of tophole sections in deepwater operations is very challenging due to the conditions in which those jobs take place. Tophole sections in deepwater operations often have a narrow margin between the pore and fracture gradients and shallow hazards, such as gas or water flow, associated with them. The low temperature found at seabed results in high fluid viscosities, slow gel strength development, and delayed early compressive strength development of the slurry.

To optimize the low-temperature slurries currently used, a novel low-temperature dispersant was developed that enables designing the slurry to meet the required properties. The new dispersant has several main benefits in slurry design and properties. The dispersant enables the slurry to develop faster gel strength and has no retarding effect compared to conventional dispersants. The new dispersant will provide a flat rheology over time, allowing better control of the circulating pressures during placement.

Laboratory tests show less gelation and an improvement in static gel strength development as compared to current dispersants. The dispersant also provides better rheological properties, often at lower concentrations, thereby facilitating a simplified slurry design.

Following laboratory testing, the low-temperature dispersant was introduced in Gulf of Mexico operations with very good results. Operationally, the dispersant is easy to handle. It is compatible with all typical cementing additives and can be used with conventional cementing equipment and liquid additive systems.

The low-temperature dispersant has been used in various types of deepwater slurries such as lightweight, conventional, and foamed slurry system, using drill water or seawater as the base fluid, often requiring less concentration and improving key slurry properties to achieve successful cementing operations in challenging low-temperature conditions.
A Review of the Corrosivity and Degradability of Aminopolycarboxylic Acids
Authors: Almubarak Tariq , Ng Jun Hong , Nasr-El-Din Hisham
Published: April 2017

Aminopolycarboxylic acids (APCA) have been used in a variety of application in the oil and gas industry. These applications include scale removal, standalone stimulation, and iron control. Because of the recent developments in this industry, the chemicals are required to function under harsher conditions. Knowledge of APCA corrosivity and degradation properties is important in designing successful treatments. Understanding the degradability of fluids used is also important for proper post-treatment fluid disposal. The objective of this work is to give the reader a better understanding of APCA degradability and corrosivity in the oil and gas industry.

This paper reviews results that were obtained through various laboratory tests, which aid in understanding chelating agent interactions with metals and their degradation. Results were obtained through a variety of tests including corrosion tests, Inductively Coupled Plasma (ICP), Mass Spectrometry (MS), Nuclear Magnetic Resonance (NMR), chromatography, and gel filtration.

At high temperatures, conventional acids such as hydrochloric acid (HCl) show severe corrosion, lack of penetration and sludging characteristics. Several organic acids were proposed to solve these issues. However, even organic acids have shown solubility and incompatibility issues. Based on these shortcomings, chelating agents are often used and show good dissolving power, low corrosion, low sludging tendencies, excellent iron control, and some are highly degradable and environmentally friendly.

This review summarizes work done in determining the corrosivity of chelating agents at bottomhole conditions and their susceptibility to photo-, bio-, and thermal degradation. Many papers were reviewed to provide a better understanding of corrosion caused by chelating agents, their operational limits, and their resistance to various degradation techniques. Readers can expand on this paper to further understand the wide range of applications chelating agents can offer the oil and gas industry and their impact on the environment.
Exploration of Applications of Metallic Additive Manufacturing for the Oil and Gas Industry
Authors: Zhong Allan , Ornelaz Richard , Krishnan Karthik
Published: April 2017

Additive manufacturing (AM) or 3D printing is a novel method of manufacturing. With this method, a part is built by the addition of material on a layer-by-layer basis, as opposed to traditional manufacturing, in which portions of a block of material are removed until only the desired part remains. The metallic AM technology has matured rapidly in the past five years and is now used across many industries, including aerospace, medical, and automotive. This manufacturing technology can also provide many benefits and opportunities for the oil and gas industry.

This paper presents a survey of existing metallic AM technologies with their advantages and disadvantages. Challenges encountered in the application of AM are discussed, which include printability, printed material properties, design for AM, and technical competency in AM. Selected work on printing various downhole tools, such as flow control related flow manifolds and an extrusion limiter, is used to illustrate the benefits of metallic AM.

Metallic 3D printing has been shown to significantly reduce the cost and time for prototyping geometrically complex components, which are either very expensive or impossible to manufacture using traditional methods. Many challenges are associated with the fabrication of 3D printed parts, and techniques to overcome these challenges are developed. Metallurgical properties of printed metals, such as yield strength, elongation at break, and impact strength, are measured using specimens made in-situ along with the parts and compared to those of wrought materials. The paper also describes the effect of build direction on mechanical properties. The results of physical tests on a 3D printed flow manifold will be presented in a separate paper.

In addition to making geometrically complex tools, reducing number of parts in a multi-component tool, and providing the capacity for fast prototyping, the most meaningful application of AM is to design for functionality; this can be achieved through the topological optimization of tool design. An outlook is presented of the path forward for applications of metallic AM for oil and gas applications.
Time-Lapse Attempt Using AUV Survey Data in Geohazards Prone Area, Results and Lessons Learned
Authors: Unterseh Stephan , Letaief Walid
Published: April 2017

In the context of a field development in deep offshore West Africa, 1200 to 2000m water depth, we have collected three high resolution datasets (bathymetry, side scan sonar mosaics and 2D sub-bottom profiles), spatially overlapping and acquired within a 6 year period using Autonomous Underwater Vehicle (AUV) technology. Since the area is geohazard prone, with the occurrence of multiple hydrocarbon-fluid migration features (pockmarks, asphalts domes, High Impedance Reflectors (HIR), etc.) at or near seabed, the analysis of the different datasets, following a time-lapse approach, was a unique opportunity to investigate the potential evolution of these geohazards over an engineering time-scale. Our study presents the methodology deployed to compare the datasets, with a particular focus on quality control to properly estimate changes over time on the seabed and within the shallow overburden.

None of the AUV datasets were designed for a time-lapse approach (e.g. baseline plus monitoring survey with accurate subsea positioning, similar sensors, etc.). Consequently, significant horizontal and vertical mismatches on fixed objects (e.g. wellheads), clearly associated with positioning and measurement uncertainties were identified. The horizontal mismatch is the most penalizing, with offsets observed randomly oriented and up to 7m. To overcome this mismatching, we based our analysis on a method developed by Gafeira et al. (2012), which provides semi-automatically geomorphological characteristics of pockmarks. The method is applied to each bathymetry dataset and the numerical outputs are directly compared using a Geographic Information System (GIS). Any pockmark showing significant changes through time (above the vertical and horizontal uncertainties) is thoroughly analysed to detect any unreliable data, before final time-lapse comparison, including interpretation of the other AUV sensors (e.g. sub-bottom profiler).

The methods detected 670 pockmarks in overlapping areas of the three datasets. The analysis of their geomorphological characteristics confirmed that 5 of these pockmarks have potentially evolved over the 6-year period between the surveys. Among these 5 pockmarks, 3 are localized on top of a salt diapir associated with hydrocarbon fluid migration. Modifications are only observed at the very bottom of the pockmarks (no widening) and consist only in a localized depression reduction. In the same area, the interpretation of 2D sub-bottom profiles reveals changes over time of HIR buried depth (upward migration). Simultaneous modifications in time at seabed and within the overburden suggest an area of active hydrocarbon migration.

This study reveals unprecedented information regarding the potential evolution of hydrocarbon migration features over an engineering time-scale. It also provides quantitative information regarding positioning uncertainty effects and proposes a methodology to compare datasets not specifically designed for a time-lapse approach.
Reliable and Accurate Determination of Life Extension for Offshore Units
Authors: Boutrot Jonathan , Giorgiutti Yann , Rezende Flavia , Barras Steven
Published: April 2017

As offshore units near the end of their design life, Operators are often faced with the requirement of extending the operating life of the facility, either to continue producing from an existing and still productive field, or to pursue new opportunities and/or defer new CAPEX as is often the case with MODUs, construction and support vessels and leased production units.

Life extension presents a unique engineering challenge from the perspective of risk management; requiring a complete structural re-assessment of the facility, from its current, as-is condition in order to determine the remaining life of the unit, along with any repairs required in order to achieve the desired additional service life.

This paper describes a methodology, developed by Bureau Veritas, for the engineering reassessment of aging offshore units that will help operators with decision making relating to life extension. It will focus on the two main degradation mechanisms affecting the structure: corrosion and fatigue.

Resulting directly from Bureau Veritas's digital transformation strategy, the methodology is built around the concept of a 3-D "digital twin" model of the asset, which is updated periodically and automatically with critical inspection data collected by connected surveyors. This facilitates continuous updating of the model to ensure a "real-time" equivalence to the "as-is" physical asset.

Furthermore, interfaces between the "digital twin" and conventional structural and hydrodynamics analysis software enable accurate condition assessment analyses to be performed, at any time, on the current state of the asset; providing critical information to be used in the assessment of feasibility of life extension and in determining actual expected remaining life.

In the event of extended life operations, the output of these condition assessment calculations can also be used to develop a Risk-Based Inspection (RBI) programme, based on the criticality and condition of each structural element, to monitor the critical degradation mechanisms, and measure and predict on-going degradation and calculate any consequences to the actual remaining life, using the continuously updated "digital twin". This approach maximizes the useful life of any facility while minimizing the overall cost of inspection, without compromising safety.

While the focus of this paper is life extension of existing assets, this methodology is equally applicable and valid for application on new-build assets, allowing risk-based and just-in-time management of maintenance and repair operations as well as real-time determination of existing asset life from the earliest stages of an assets deployment.
Strength Assessment of Degraded Mooring Chains
Authors: Crapps Justin , He Haiping , Baker David , Bhattacharjee Subir , Majhi Sai , Wilutis Erik
Published: April 2017

This paper presents a framework for strength assessment of degraded mooring chains, based upon laboratory break tests and finite element simulations of degraded chain. Four different modes of degradation, all observed in the field, are considered including: 1) general corrosion, 2) localized corrosion with large single and dual pits, 3) interlink wear, and 4) chain abrasion due to contact with the seabed. For each case, laser scanning was used to obtain the actual geometry of degraded chain taken from the field and the links were then loaded in tension to failure. Material properties were derived from coupon tests of adjacent links to those loaded to failure and the analytic predictions were compared with the actual break loads for each case, validating and demonstrating the robustness of the method. This paper discusses the strength capacity of mooring chains and does not discuss load or demand placed on the mooring system or fatigue endurance of degraded chains. However, mooring system demand will be an integral part of the holistic evaluation of any degraded chains.

Case studies detailing the development of strength assessment curves for general corrosion, interlink wear, abrasion, and localized corrosion are presented. A comprehensive investigation covering these four degradation modes is not available to the industry at present. The assessment methodology has a strong technical basis and is expected to provide significant improvements to current industry practice.
Guidance for Performing Time-Domain Mooring Analysis of Floating Systems in Squall Environments
Authors: Oberlies Robert R. , Bhattacharjee Subir , He Haiping
Published: April 2017

This paper describes a methodology for the design and analysis of offshore floating systems governed by squall wind events. A clear methodology on this subject currently does not exist in industry codes and standards. A well-defined methodology is necessary because squalls govern the strength-based design of moored systems in areas such as offshore West Africa.

This work focuses on the identification of load cases for time-domain analysis of wind squall events for spread and turret moored vessels. This paper also proposes a method for determining the characteristic design value of extreme line tension and presents various approaches for characterizing extreme vessel offsets. These recommendations are supported and illustrated using results from time-domain analyses of three different offshore systems: two turret-moored ships and one spread-moored ship.

This work identifies the conditions that determine maximum offsets and mooring line tensions. These correspond to (1) the relative heading between the vessel and the squall, and (2) the characteristics of the squall. This paper highlights:Modeling details, sensitivity cases, and convergence studies used to establish confidence in characteristic design values that result from the analyses;The number and type of squalls to be considered and identifies topics requiring further research

The recommendations in this paper can provide a basis for updates to industry codes and standards related to the design of mooring systems governed by squall events. Prior to the updating of codes and standards, the recommendations included here can be applied to future analyses of moored systems governed by squall events.
Systematic Use of Real Time Data Analysis for Primary Cementing and Cement Job Verification
Authors: Gomes Paulo J. , James Mark , Therond Emmanuel
Published: April 2017

Operators and service providers have been working together to push the boundaries of real time data analysis. This work describes a software tool that allows visualisation and interpretation of data streaming from the rig during a primary cement job. Algorithms running in the background allow users to check if the operation is proceeding per plan and to make informed decisions in real time and perform rapid post job evaluation and cement placement verification.

This tool was developed to take advantage of an integrated platform: design and execution information are merged with real time data. It has been deployed globally on 13 rigs with hundreds of primary cementing jobs monitored successfully. This paper describes the tool's capabilities in detail, including: A methodology for the assessment of losses in real time to evaluate the impact on Top of Cement.A methodology for the real time estimation of Top of Cement using pressures measured at surface during cement job execution.To display key job parameters monitored in real time and provide efficient comparison to the job plan.To display fluid interface positions, updated in real time, on a representative Wellbore Schematic taking lost volumes into account if applicable.

The paper will also use case histories to compare and validate the Top of Cement output, from the real time analysis of surface pressures, against Cement Bond Logs.
Improving the Fatigue Performance of SCRs via a Special Touchdown Zone Pipe Section
Authors: Mansour G. , Forbes W. , Thethi R. , Hays P. R.
Published: April 2017

A special section of seamless pipe machined on the inside and outside to have upset ends is used at the touchdown zone of a 20in oil export steel catenary riser (SCR) in order to improve the fatigue life. This paper covers the drivers for the choice of this special section, procurement, management of challenges, and lessons learned. The chain of supply (pipe, machining, coating, welding, and fatigue testing) involved several suppliers across several countries posing another challenge.
Defining the Difference Between Laboratory and Field-Generated Foamed Cement
Authors: Cunningham Erick , Heathman James , Kutchko Barbara , Benge Glen , Maxson Joe , DeBruijn Gunnar , Buford Charles
Published: April 2017

Foamed cement has been used extensively across a variety of applications for oil and gas well cementing, including deepwater riserless cementing, low fracture gradient cementing, horizontal well cementing, steam injection well cementing, and high-pressure/high-temperature (HP/HT) cementing.

When using foamed cement, laboratory testing is used to estimate the performance characteristics of foamed cement slurries that are designed for well applications. It is well known that significant differences exist between the methods used to generate foamed cement in the laboratory and those used to generate foamed cement for field applications. The implications of these differences on foamed slurry characteristics (e.g., bubble size distribution) and performance properties (e.g., stability, permeability, mechanical properties) has not been well analyzed or well understood.

This paper documents a project that was undertaken through a joint effort between API Sub-Committee 10 and the National Energy Technology Laboratory (NETL) to examine the differences between foamed slurries generated with laboratory equipment and field foamed cementing equipment. Methods for generating and capturing foamed cement samples using field equipment are discussed, as well as analytical methods for evaluating the characteristics of foamed cements. References to the resulting data are provided. Finally, conclusions and recommendations are presented that were developed during the course of the project.
Two-Stage De-Oiling Testing for Qualification with MEG Presence
Authors: Riesenberg J. M. , Biega Brandon , Tienhaara Mika , Lammers Bart , van Deurzen Bente
Published: April 2017

Chevron Energy Technology Company performed a flow loop qualification under realistic conditions for a two-stage de-oiling unit in order to test the performance and robustness, especially for subsea developments. The objectives of this qualification were to investigate the effects of both high pressure and the presence of mono-ethylene glycol (MEG), under as realistic conditions as possible, on the system performance using crude oil and water. MEG is a gas hydrate inhibitor which will likely be injected in long subsea tie-backs.

The tested compact produced water treatment system consisted of a two-stage de-oiling arrangement in which the first stage was a bulk de-oiler hydrocyclone, and the second stage was a polishing hydrocyclone. Each stage consisted of a pressure vessel which was filled with multiple hydrocyclone liners. For this qualification, Sulzer's MixedFlow De-Oiling Liquid-Liquid Hydrocyclone technology was used. Sulzer hydrocyclones utilize a design with multiple openings in the inlet as well as a swirl generation element, resulting in a stabilizing and coalescing effect on the oil-water flow. The system was tested at a high pressure test loop with crude and methane to provide the most realistic testing conditions. Tests were also performed with MEG in the feed. MEG is required for gas hydrate inhibition, and under some operating conditions MEG can influence de-oiling efficiency during produced water treatment. For this reason, test points with and without MEG present in the feed were included in the test matrix.

The impact of the inlet conditions (temperature, pressure, oil in water (OIW) concentration, e.g.) on the de-oiling system performance was investigated. The system was tested with temperatures as high as 70°C and pressures as high as 51 bar(g). System efficiencies approaching 99% were found for many cases and pressure drop was measured to be significantly less than that which is expected of similar de-oiling systems. The performance and robustness of this design resulted in a successful qualification of all parts of the system.
Fluid-Front Tracking in a Mature Jurassic Carbonate Reservoir using Innovative Pulsed Neutron Solutions for the First Time Offshore Abu Dhabi
Authors: Serry Amr Mohamed , Espinassous Marianne , Bilbeisi Jawdat , Saldungaray Pablo , Zhou Tong , Rose David , Dasgupta Suvodip
Published: April 2017

Managing mature fields effectively and efficiently requires monitoring changes in formation fluid saturations as well as production from individual wells. Reservoir saturation monitoring is usually performed using slim pulsed neutron logging (PNL) tools because they can be deployed through tubing and operate in different modes, thus providing a wealth of information. However, several environmental factors can complicate the analysis, including complex completions and unknown or variable borehole fluids (gas in particular), which affect the PNL raw measurements and computed outputs. Factors related to the nature of the reservoir, such as complex lithology and multiple fluid phases, further complicate the analysis, making accurate fluid saturation evaluation and reservoir fluid-front mapping very challenging.

An innovative pulsed neutron technology, recently introduced in the UAE, can help in reducing the evaluation uncertainty. The new device is fitted with multiple detectors and is used with newly developed algorithms to provide self-compensated formation sigma and hydrogen index (HI) measurements, overcoming many of the limitations of previous devices in complex environments. Additionally, the new tool provides a new formation property sensitive to gas-filled porosity, called the fast neutron cross section (FNXS), which, in adequate conditions, can be used to complement the analysis or highlight gas in the absence of openhole logs.

The new PNL tool was run for the first time in an offshore UAE mature field targeting Jurassic formations. The production in the field started in the 1960s, followed in the 1970s by down-flank injection of water with much lower salinity than the connate water, and in the 1990s by crestal gas injection. The Jurassic reservoir mineralogy is a complex mixture of calcite, dolomite, and anhydrite. Completions consist of multiple combinations of tubing, casing, and hole sizes along with packers and other hardware components; often the borehole is filled with gas across the zones of interest, which has proven an obstacle to PNL interpretation. The new PNL device was tested in several wells in which it operated in inelastic gas, sigma, and HI (GSH) mode and carbon/oxygen (C/O) mode. Integration of all the recorded information made possible to reliably track the three-phase fluid saturation changes even in the gas-filled wellbores with complex completions. An additional benefit with the new tool was that because the C/O data were recorded at a speed twice as fast as that of the previous-generation PNL tool, it was possible to acquire the logs in the limited allocated time to help resolve the oil saturation in reservoir zones with variable salinity. The saturation analysis was compared to production logs and well production data where available.
Assessment of the Combined Hurricane and Loop Current/Loop Current Eddy Risk on Existing Mooring System
Authors: Zhu J. , Driver D. , Petruska D. , Xia D.
Published: April 2017

A strong Loop Current or an Eddy (LCE) persisted in the Gulf of Mexico through the peak hurricane season of 2015 and impacted several BP floating facilities. It was a concern that if a hurricane passed near one of the floating facilities in the presence of LCE, the combined loading may increase the probability of exceeding the mooring system design capacity. As a result, this type of combined event could be more severe than the original hurricane or LCE only design case. Therefore, a long term combined hurricane and LCE risk was evaluated. Since metocean criteria for this type of combined event is not readily available, two approaches were compared: 1) combining observed average LCE speed at the site with the N-year return period hurricane only metocean; 2) reconstructing a long time series of combined LCE and hurricane data and developing N-year return period criteria from this.

The first approach is straightforward; however, it proved to be too conservative, while the second approach reflects a more realistic scenario. Both approaches were applied to evaluate the long term mooring line risk. The critical environmental direction and tension levels were identified to determine minimum factors of safety on mooring components breaking strengths. The results indicated that the mooring line risk of a 1000-year return period combined event is equivalent to the risk of a 100-year hurricane only event.

The other aspect of Loop Current risk is the potential inability of the platform to get back to the nominal position if it is at an unfavorable position during a LCE event. It is possible that the mooring tension could be above the chain jack operational limit due to increase loading from the LCE while also offset from the neutral position, thus increasing the risk of mooring or riser overloading. Different mooring operational options were compared to select the proper strategy to reduce the operational risks. The final operational recommendations were tested in the field to confirm fitness for operation.
Evaluation of the Intrinsic Conservatism in the Design Codes for Subsea Mudmats
Authors: Riet B. A. M van de , Yenigul N. B. , Burgers R. , Pisanò F.
Published: April 2017

Rectangular mudmat foundations for subsea structures are commonly designed according to ISO and API guidelines. However, the modern trend towards deeper waters and heavier structures is currently challenging traditional approaches to foundation design, especially in presence of particularly poor soil conditions. The intrinsic conservatism carried by design codes may not only lead to higher fabrication/installation costs, but also conflict with the operational limits of existing installation vessels.

Based on the analysis of four design cases, it is argued that ISO/API safety factors may be from 1.5 to 2.3 times as low as the predictions of elastoplastic finite element (FE) simulations. Such a conservatism is also found to considerably increase with the embedment depth, whereas the influence of the foundation aspect ratio is nearly negligible. A simple calculation example shows that the systematic use of numerical analysis in design may result in a 47% reduction of the total foundation area, and an overall decrease in fabrication costs of approximately 16%.