bluuebunny/crossref_metadata_2025_split huggingface dataset:
All-Electric as an Enabler for More Cost Effective Developments on Cluster Systems
Authors: Winther-Larssen E. , Massie D. 
Published: April 2017

Abstract

Objectives
There is an increased need for cost effective subsea technology to enable oil companies to have more flexibility in system architecture and also enable access to developments in deeper water and with longer step-outs than before. As the current subsea production systems struggle to meet those challenges, the need for a suitable, flexible and cost efficient technology has emerged. All-Electric systems have this capability. By using the Aker Solutions developed portfolio of products and concepts this paper will show cases of simplified, easy integratable and cost reduced All-Electric solutions that can be installed independent of depth.
The paper will also touch upon the advantages of All-Electric systems in terms of reliability compared to traditional electro/hydraulic systems.

Methods, Procedures, Process
By integrating automotive and telecom competence with subsea expertise, it has been possible to implement a rigorous design-to-cost mind-set in the development of the various All-Electric system building blocks.
All-Electric hardware and software will give large benefits in terms of OPEX and be competitive in CAPEX (in addition to enabling improved environmental impact, increased levels of safety and increased functionality).
Some of these benefits will be further enhanced when applying subsea and downhole All-Electric technology solutions on a wider scale.

Results, Observations, and Conclusions
The paper explores the potential benefits an All-Electric system can have both in relation to CAPEX and OPEX.

Novel/Additive Information
Electric actuation, sensing, integrated power management and control offer the promise of smaller, lighter and more cost effective subsea production systems. They also offer the potential for more precise measurement, control and maintenance monitoring over time compared to their hydraulic counterparts, which enables planned maintenance of equipment, with significant benefits in terms of reduced OPEX.
Soil Model Assessment for Subsea Wellhead Fatigue Using Monitoring Data
Authors: Mercan Bulent , Chandra Yenny , Campbell Mike , Ge Michael Long 
Published: April 2017

Abstract
A significant effort is made by the industry through analyses and field monitoring to ensure delivery of safe and reliable wells. Fatigue analysis is an important aspect of well integrity assurance. Structural fatigue damage arises from stress changes caused by environmental cyclic loads acting on the riser system. In practice, the conductor-soil interaction under cyclic loading is modeled using the soil resistance-displacement (P-y) springs. Use of an appropriate soil model is essential for accurate determination of the fatigue damage. The American Petroleum Institute recommendations (API 2011) for P–y curves, which are often used for conductor–soil interaction analysis, have originally been developed for piled foundation and are inappropriate for well fatigue analysis. To that end, a new approach was developed by Zakeri et al. (2015) to derive P-y curves specifically for well fatigue analysis. Ultimate performance of each soil model can be determined and verified with field monitoring. This paper presents results of a field monitoring campaign for a well drilled in 354 ft water depth within a complex seabed stratigraphy comprising sands (loose to dense) and clays (very soft to stiff). Design, calibration and verification of the riser/conductor structural model using field data are presented in a companion paper (Ge et al. 2017). Herein, the effect of soil modeling on wellhead fatigue is discussed and predictions made with the API (2011) and the Zakeri et al. (2015) soil P-y springs are compared to field monitoring data. For the case presented herein, the results indicate that the Blowout Preventer (BOP) stack motion response is significantly affected by the soil stiffness and modeling methods. The predictions made with the Zakeri et al. (2015) model provided BOP response similar to those observed in the field both above and below the mudline. Whereas, the analyses done with the API (2011) model significantly overestimated the ‘measured’ conductor fatigue life above the mudline and underestimated it below. The results of this monitoring program are a step forward in better understanding system behavior of offshore wells.
Axial Compression Fatigue in Long-Lay-Length Fiber Mooring Ropes
Authors: Flory John F. , Banfield Stephen J. , Ridge Isabel M. L. , Carr Robert 
Published: April 2017

Abstract
Rope failure due to axial compression fatigue was found in two recent rope investigations. One of these was an HMPE mooring line on a gas carrier and the other was a nylon SPM hawser. In both incidents, the unusual rope design, with very long rope and strand lay lengths, was the root cause of the failure.
This paper first describes axial compression fatigue and how it can occur in fiber ropes. It briefly discusses a past failure of an aramid rope caused by axial compression fatigue. It describes the two more recent failure incidents. It describes how long-lay-length rope designs caused or contributed to the axial compression fatigue which resulted in rope failure.
This paper describes the axial compression fatigue test method. It reviews the axial compression fatigue performance for aramid and HMPE yarns from the Fiber Tethers 2000 JIP and presents new data for HMPE yarns and also for nylon yarns, which have never before been tested for this property.
Recommendations are made for fiber rope designs. Unless they are properly designed for the application, ropes with long rope lay and long strand lay lengths should not be used in the following situations: *Cyclic tension with many cycles down to low trough loads.*Cyclic bend over sheaves.*Cyclic rotation of the rope.
Wave Energy Converters and Tidal Energy Converters Road to Commercial Viability
Authors: Gehring Donald H. 
Published: April 2017

Abstract
This paper will report on the status of the US power industry today and how close some Marine Energy Converters (MECs) options are to becoming commercially viable in the near future. The paper provides an overview of the rules and regulation that have been written in preparation for MEC entries into the power market place, some of the costs of full scale Wave Energy Converters (WECs) and Tidal Energy Converters (CECs), how these costs compare to existing new power plant options and some new promising lower cost MEC developments to look for in the near future.
Time Lapse 4d Assessment of Shallow Water Seabed with Repeated Multi-Beam Hydrographic Surveys
Authors: Geldof J -B. , Naankeu-Wati G. , Labaune C. 
Published: April 2017

Abstract
Characterization of coastal erosion is paramount to ensure the integrity of any oil and gas facilities. Geophysical surveys are mandatory to build ground models of these particular areas to understand sediment movements and control the risk for the coastal infrastructures safety.
Based on past experiences, infield acquisitions and interpretations have fundamentally been improved to acquire recurrent high precision Multi Beam Echo Sounder (MBES) data with the objective of 4D interpretation. Using a recently developed algorithm addressing budget error (Naankeu-Wati et al., 2016), measurement uncertainty of bathymetric soundings has been thoroughly evaluated.
Beside the description of innovative acquisition methods, new data interpretation and processing techniques are revealed. For a particular area of interest, the paper shows the essential role of digital geographic tools and particularly Geographical Information Systems (GIS) to interpret 4D hydrographic data. Based on the Bathymetric Position Index (BPI) algorithm, a workflow has been built to automatically map seabed features such as sand waves from time-lapse dataset. Such automatic mapping method affords improving the quality of seabed features comparison through the time by limiting subjectivity of data interpretation.
Baseline for Planning and Cost Estimation of Brazilian Decommissioning
Authors: Mimmi F. , Ralston S. , Silva M. Miguel , Silva P. Martins 
Published: April 2017

Decommissioning and abandonment of Brazilian offshore oil & gas fields has become more important in the last few years due to the maturing hydrocarbon producing basin in the region. However, a complete abandonment of a Brazilian offshore field has not been completed to date and the consequent lack of a reference case leads to uncertainties with operators and stakeholders during the conceptual phases of abandonment, when identifying the best decommissioning option and estimating a reasonable cost for the complete program of decommissioning activities.
This paper aims to satisfy this uncertainty and develop a Brazilian baseline for front end planning and cost estimation of the decommissioning, removal and disposal options.
The methodology presented in this paper is based on analysis of the national and international regulations applicable to decommissioning, the expectation of stakeholders and national supply chain benchmarking. Drawing on the conclusions of this analysis, the paper then presents the available decommissioning options generally applicable for fixed platform, floating platforms, pipelines and subsea facilities. The eligibility of each decommissioning option is then investigated against the background of current Brazilian regulatory requirement, highlighting those cases where the options are not mentioned in the legislation or where contradictions exist. Further analysis of the options is then undertaken to determine the preferred solution from the stakeholder perspective and to also define national supply chain benchmarking of the options to confirm whether the national supply chain can support the future potential demand for decommissioning in Brazil.
Finally, the paper shows a comparative case study for the high-level planning and cost estimation for the decommissioning of a complex of small fixed platforms including the plugging and abandonment (P&A) of the platform wells.
Design of the Disconnectable Buoy Turret Mooring for the Turritella FPSO
Authors: Leverette Steve 
Published: April 2017

Abstract
The Stones Field FPSO design provided many challenges in the design of the disconnectable Buoy Turret Mooring (BTM), including the 2900m (9500ft) water depth (the world's deepest floating production system), the first use of steel lazy wave risers from a BTM system, the local environment which included Rossby Topographic Wave currents along the Sigsbee Escarpment, and especially the efficient and safe mating and un-mating of two large floating bodies at sea without use of support vessels.
The paper covers the overall philosophy of the disconnect/reconnect operation of the turret/buoy, and then describes the major design challenges encountered. The major system components will be described. The functional aspects of the disconnection and reconnection will be discussed, with discussion of how the particular challenges of the project drove the design.
A sequence of increasingly complex model tests was used to guide the design. These initially included forced motion and drop tests to define the hydrodynamic properties of the buoy and the hydrodynamic near-field interaction of the buoy and a fixed FPSO turret. Later tests modeled the full system in waves while disconnecting and reconnecting. The model test results were then used to calibrate a numerical simulation which was used to refine and validate the design. A follow-on paper by Carrico and Leverette (2017) describes the test programs in detail.
Stones Development: A Pioneering Management Philosophy for Enhancing Project Performance and Safety
Authors: Lohr Curtis , Pena Maria 
Published: April 2017

Abstract
The Stones Project is Shell Offshore Inc.'s ("Shell") play opener discovery in the outer Lower Tertiary trend in the Gulf of Mexico ultra-deep water (~9,500 ft. water depth). The initial plan is a phased development, with an FPSO and 8 initial wells for Phase 1, potentially followed by a Phase 2 development after field performance is confirmed. The Stones FPSO is the deepest floating production system in the world. This paper will provide an overview of the Stones project, discussing the challenges that had to be overcome and the innovations that were developed to successfully deliver this ground breaking project.
Pipe-Soil Structure Interaction: Best Practices for Spools, Buckle Initiators, End Connections and Sand Waves
Authors: Bransby M. F. , Ramm M. , Zhou H. , Low H. E. , Fugro A. G. , White D. J. 
Published: April 2017

Abstract
Pipe-soil interaction behavior forms a key input into the design of pipelines. The global response of the pipeline can be critically affected by the resistance provided by the seabed. Accurate modeling of pipe-soil interaction behavior leads to improved reliability and can lead to design optimizations that offer considerable cost benefits.
Extensive recent research and advances in design approaches, particularly through the development of high pressure high temperature lines, has led to significant revisions and improvements to pipe-soil interaction modeling over the past decade. There are now well-established techniques for estimating the as-laid embedment and axial and lateral pipe-soil interaction responses – the non-linear ‘springs’ used in pipeline structural modelling – for pipelines laid on the seabed. However, these methods, as applied in practice, generally involve the key assumption that the pipe exerts a vertical force on the seabed, V equal to its submerged self-weight, W – the ‘V=W assumption’. However, this assumption is not appropriate for pipe elements that are close to points of fixity, constraint or vertical upsets – e.g. in-line tees, buckle initiators and sand waves – or which form spools.
This paper illustrates examples of all of these situations, showing pipe-soil interaction ‘springs’ generated with and without the ‘V=W assumption’, to show the contrasting behavior. Recommendations are provided for practical modeling of this soil-structure interaction behavior.
In some design scenarios, the pipeline may be sufficiently robust that adoption of the ‘V=W assumption’ may not affect the integrity of the design. In other scenarios, it may be necessary to eliminate the ‘V=W assumption’ in order for a satisfactory design to be demonstrated. This may be achieved by performing integrated soil-structure interaction analyses, or through iterative refinement of the pipe-soil ‘springs’. In all cases, an awareness of the ‘V=W assumption’ is required across the pipeline engineering and geotechnical teams, who should interact to determine the appropriate basis to demonstrate an acceptable design.
How the Application of LGS Technology for Drilling Risers Reduces Drilling Costs Through Improved Operability
Authors: Kurts P. , Marcollo H. , Potts A. E. , Johnstone D. 
Published: April 2017

Abstract
Drilling risers are regularly deployed in depths beyond 5000 ft with large sections covered in buoyancy. The smooth cylindrical shape of buoyancy modules can result in significant VIV response, causing overall amplification of drag experienced by the riser. In turn, operations can be suspended due to drag effects on top and bottom angles; high current speeds can lead to a halt in operations, even complete disconnection and retrieval of the riser string. Although suppression technologies exist to reduce VIV response (helical strakes/fairings), these have not been integrated into the manufacture of buoyancy modules for practical reasons (stackability, ease of manufacturing/assembly/installation). Innovative Longitudinally Grooved Suppression (LGS) technology has recently been developed and tested with two main bodies of work undertaken; model testing and full scale numerical modelling. This paper covers the methodology and results of full-scale OrcaFlex/SHEAR7 simulation work performed on drilling risers in realistic current profiles for the Gulf of Mexico (GoM), concluding with the impact this technology could have in reducing costs by increased operability for drilling risers. LGS technology provides significant reduction in VIV response whilst maintaining similar buoyancy to conventional modules. Significant reduction in VIV response has multiple benefits: less drag, reduced fatigue damage, and an increase in maximum currents drilling risers can be operated in - without any moving parts or extra deployment installation time. High Reynolds Number model testing results showed LGS technology behaved favorably in observable repeatable conditions, whilst the full scale numerical modeling demonstrated how these parameters measured in model testing can be used to perform numerical modelling of full scale offshore drilling risers in a variety of water depths and conditions; improving operability and riser fatigue life. Operability during GoM eddy current events was calculated to increase 30% annually, equating to estimated annual savings of over $10M, with potential to save similar amounts within a short period in the case of extreme current events. By applying LGS technology, significant financial savings can be achieved through increased operability and increased fatigue lifetimes.
Air Gap on Semisubmersible MODUs Under DNVGL Class - Current & Future Design Practice
Authors: Pessoa J. M. , Moe A. M. 
Published: April 2017

Abstract
In light of recent incidents involving wave impact on the deck box and superstructures of semisubmersible MODUs there has been significant effort in reviewing and revising the regulatory regime governing the air gap of such units. An Offshore Technical Guideline (DNVGL-OTG-13) was published in draft edition by DNVGL in autumn 2016 with guidelines for air gap calculations that present several changes to what has been considered industry practice. This paper will, based on a generic semisubmersible MODU design, investigate the differences between what has been considered industry practice and the new guidelines. Focus of the evaluation will be on calculation of the wave-frequency contribution, namely on wave asymmetry factor and viscous damping influence on results. Further, the low-frequency contribution will be investigated. Results calculated using a fixed roll/pitch angle suggested by DNVGL are compared to results attained by calculating the actual low-frequency motions due to waves and wind. Low-frequency wave-induced exciting moments calculated with Newman's approximation and the full QTF are compared to assess the approximation's validity for this problem. Finally a full air gap analysis based on what has been considered industry practice and the new OTG-13 practice will be performed and compared with the aim of assessing the short term impact to the industry.
Seismic Response Spectrum in Lieu of Time History Analysis for Subsea Structure Design
Authors: Wang George , Loh Michelle , Peng Yen-Tun , Shen Joanne , Genesis P. E. , Malachowski Jim 
Published: April 2017

With oil and gas exploration venturing into more seismic prone regions for global deep water developments, seismic assessment of subsea structures becomes a fundamental part of the design requirements of regulations, industrial codes and standards. This paper demonstrates a response spectrum analysis approach for the seismic design of subsea structures. Response spectrum analysis using commercially available dynamic software package is a time-saving and preferred method for the design of subsea structures as compared to the time history method for the seismic assessment. The study also intends to contribute to the standardization of the seismic design procedure for subsea structures.
The paper selected a typical subsea valve skid with a mudmat foundation for the seismic response spectrum analysis. Upper and lower bound values of soil springs were included to capture the response in relation to varying degrees of soil strength. To benchmark the time-saving advantage of response spectrum analysis, time history seismic analysis is also performed in parallel on the same subsea structure. Results of the two methods are compared to establish a technical position that the response spectrum is a more favored and efficient approach as compared to time history for the design of subsea structures.
For the subject structure, the response spectrum analysis results show that the structure remains elastic during ELE (Extreme Level Earthquake) and ALE (Abnormal Level Earthquake) seismic events. This is due to the low-rise geometric profile of subsea structures. The results also indicate that the response spectrum approach enables a faster and relatively accurate estimate of structural response with ELE/ALE loading while still using a linear method.
The response spectrum analysis serves to bridge the gap between a rough approach of directly applying a simple additional seismic acceleration on the structure, versus subjecting the structure to a time-consuming time history analysis. This time history analysis is not deemed necessary due to the smaller sizes hence the less substantial inertia loads of the subsea structures as compared to typical offshore platforms. Further studies in the future should be able to provide more "accuracy vs. efficiency" type of trade-off information on a wider range of different subsea structures.
Improving Reliability of MODU Mooring Systems through Better Design Standards and Practices
Authors: Ma Kai-tung , Garrity Robert , Longridge Kent , Shu Hongbo , Yao Aifeng , Kwan Tom 
Published: April 2017

Abstract
With a goal to improve the overall reliability of moorings used by MODUs (Mobile Offshore Drilling Units), this paper reviews gaps and issues in design standards and operation practices. MODU moorings stay at one location for a short term, compared to tens of years for permanent moorings on production facilities. While the exposure time to the environment is relatively shorter, mobile moorings have been seen to experience a sizable number of failures ironically. Probability of failure has been high on the order of 10−2. Improving reliability of MODU moorings may be achieved through two sides, i.e. better design standards and more rigorous operation practices. On the design side, there appears to be a lack of clear guidance on designing a mobile mooring system to a proper return period. The gap is prominent especially for moorings in tropical cyclone (aka hurricane or typhoon) areas. Current industry codes and standards do not have a clear guidance on what return period shall be used as a minimum to account for the risk associated with close proximity and failure consequence. Some guidance is provided in API RP-2SK, but it is limited to applications in Gulf of Mexico. This paper attempts to close the gap by proposing minimum return periods to be used and requiring a quantitative risk assessment (QRA) to justify the numbers for any region with tropical cyclones. Guidance on performing a QRA is provided, and aspects on how to produce trustworthy results are discussed. On the operation practice side, issues and gaps are identified and reviewed. Often times, MODU moorings do not receive a sufficient amount of attention in system design, deployment, inspection, and equipment maintenance. Common issues are summarized to raise awareness and best practices are presented.