bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic Stability Performance of a Coastline Slope Beneath a Pipeline: A Case History of Onshore Observations for Offshore Application
Authors: Sancio R. , Rice A. , Been K. , Villet Willem 
Published: April 2016

Abstract
Under the Pacific Ocean off the south coast of Peru the Nazca tectonic plate subducts beneath the South American plate, creating a high seismic hazard along this coast. Onshore site development and preparation for LNG plant and export terminal construction in this area required a significant volume of excavation throughout the process area and storage area, which are located on a plateau cut to elevation 125 m, separated from the marine loading terminal by coastal cliffs. Steep cuts were incised into the plateau to build a 3.5H:1V sleeper way to allow the LNG cryogenic pipeline system to traverse down the cliff onto a marine jetty to reach the loading terminal. Approximately 230 thousand cubic meters of spoils resulting from the excavation of the sleeper way were pushed over the cliff onto the undercliff area. Additionally, about 630 thousand cubic meters of the stripped material from the process and tank area was pushed over the cliff onto existing colluvial materials in the undercliff. Soon thereafter a crack measuring about 0.3 m in width with a vertical displacement of 0.4 m, and sympathetic cracking occurred sub-parallel to the shoreline at numerous locations across the undercliff area.
A translational mass movement with a volume of approximately 18 million cubic meters was identified following the installation of inclinometers. Regrading of the spoil piles was designed and implemented causing the mass movement to stop. However, simplified and detailed slope stability analyses indicated that seismically-induced permanent slope displacements should be expected during significant earthquake events. A cumulative distribution function (CDF) that incorporated slope parameters and ground motion uncertainty was developed for slope displacements using the Newmark procedure. CDFs were developed conditional to the occurrence of the design earthquake events. Design displacements were selected based on owner risk tolerance and then incorporated into the design of the pipeline through: (a) the installation of a thicker wall at the location where displacements were expected; and (b) installation of an additional extensional loop on the pipeline. Shortly after completion of regrading to stabilize the mass movement, the slope was subjected to an M = 8.0 earthquake that caused permanent slope displacements in the range of 10 to 80 mm across the sliding plane.
This paper describes slope performance from inclinometer and surface movement marker data following the M = 8.0 earthquake, comparison to the results of a probabilistic prediction of seismically-induced permanent slope displacements using simplified procedures, and discussion for the analysis and design of slopes subject to earthquake induced ground motions and incorporation into subsea design basis.
Prediction of Asphaltene Onset Pressure from Dead Oil Stability
Authors: Haghshenas Mehdi , Balashanmugam Soban , Gonzalez Doris , Pietrobon Marney 
Published: April 2016

Abstract
Asphaltene deposition is a major flow assurance issue in some of the deepwater reservoirs in the Gulf of Mexico. Prediction of asphaltene onset pressure (AOP) is essential for the management of the asphaltene threat. Generally, determination of AOP requires pressurized down-hole samples with very low or no oil-based mud contamination. The opportunity to acquire such high quality samples is not always available. This paper presents a novel approach for the prediction of asphaltene onset pressure from dead oil samples based on the asphaltene instability trend method.
The asphaltene instability trend method compares the estimated live oil refractive index and the onset refractive index extrapolated to high pressure/high temperature conditions to infer asphaltene instability. The main laboratory measurements that are used for AOP prediction are refractive indices of oil-precipitant mixtures at the onset of asphaltene precipitation. The asphaltene instability prediction is based on the assumption of a linear relationship between onset refractive index and temperature and also the molar volume of precipitant. In this work, we incorporated the use of equation of state and high pressure / high temperature stock tank oil density measurements to estimate the refractive index of live oil. Also, the molar volume of solution gas was estimated by an equation of state and used to extrapolate the onset refractive index. These modifications minimized the sensitivity of calculations to the lab data and provided more accurate AOP predictions compared to the original method.
The modified approach was applied to several oil samples from the Gulf of Mexico. The estimated AOPs were within 20% of measured AOPs from live oil samples. The new method provides an alternative for asphaltene stability prediction when a high-quality bottom-hole sample for direct measurement is not available or the lab data is inconclusive.
Bridging the Gap Between Design World and Online, Real-Time, Dynamic Simulation World
Authors: Parthasarathy P. , Mai M. 
Published: April 2016

Abstract
The last twenty-five years have seen tremendous growth in the field of flow assurance and real-time flow assurance software for pipeline / asset management. There exists a great divide between dynamic multiphase flow simulations executed during the design phase of a project to that executed during operations in an online environment and this divide is usually not well understood, nor are operators / service providers adequately informed. Some of the key differences are:Design analysis is driven by project design basis and the engineer is in control of the simulations, while online systems are instrument driven and the process is in control.Accuracy is front and center of design simulators while robustness takes a secondary role, but in online systems both accuracy and robustness share equal importance.Design simulators primarily cater to design engineers who are well versed in the software while online systems cater to a more diverse audience, including operators, engineers, and management.
This paper is aimed at providing background on the issues detailed above through real-world examples. Through these examples that have been encountered during the last two decades of developing, installing and maintaining Virtuoso®, we show how real-time modelling can assist in flow assurance of a production system.
The Importance of Soil Characterization in Modelling Sediment Density Flows and Implications in Assessing Infrastructure Interaction
Authors: Ingarfield Samuel , Sfouni-Grigoriadou Mariangela , de Brier Charles , Spinewine Benoit 
Published: April 2016

Abstract
Assessing risk to subsea infrastructure from submarine mass movement events is becoming increasingly important as operators move in to deep-water environments characterized by evidence of prior mass movement activity. An integral part of this assessment is modelling the behavior of potential sediment flows, and their interaction with infrastructure. This paper presents two advanced debris flow models used in industry, and emphasizes the importance of appropriate high quality soils testing when choosing model parameters through an idealized case study, as well as a hypothetical flow simulated on real world bathymetry.
A Risk Based Approach to Managing the Integrity of Aging Production Facilities in the Gulf of Mexico
Authors: Kemp Douglas 
Published: April 2016

This paper describes how one company developed and implemented a risk-based integrity management system and applied it to operated facilities within the Gulf of Mexico.
The challenges of maintaining integrity of offshore assets change constantly throughout the life of a facility. The adoption of an Integrity Management System that integrates both risk-based and prescriptive practices can allow an operator to identify changing integrity threats and apply proactive mitigation strategies in good time. Successful use of an IMS can enhance safe operation and regulatory compliance while maintaining up time during declining production.
The paper describes the challenges faced in applying these techniques within the Safety and Environmental Management System regulatory regime and Gulf of Mexico operating culture and reviews Lessons Learned in developing and implementing the Integrity Management Systems
The paper describes how the IMS facilitated the assessment of platform condition and remaining life and how this in turn influenced the remediation requirements and subsequent maintenance and integrity activities required to facilitate life extension.
Mitigating Wax Deposition From Crude Oils: Correlations Between Physical-Chemical Properties of Crude Oils and the Performance of Wax Inhibitors
Authors: Perez Peter L. , Gurnon A. Kate , Chichak Kelly , McDermott John , de Paulo Jaqueline , Peng Wenqing , Xie Xiaoan 
Published: April 2016

Abstract
In this paper, we explore the correlations between the effectiveness of several wax inhibitors and physico-chemical properties of crude oils. First, the effects of the type of fluid was studied by dissolving refined paraffin waxes in non-waxy crude oils—here termed "doctored" crude oils—of different properties and comparing the wax appearance temperature and pour point of the doctored crude oils to those determined for a model waxy fluid used in previous studies [1]. After treating the doctored crude oils with wax inhibitors, the ability of the chemicals to depress pour point was examined. Even though the paraffin waxes in these fluids were exactly the same, marked differences in the effectiveness of the chemicals were observed. The doctored condensate was very responsive to the inhibitors in a similar manner to that observed for the model waxy fluid, while doctored crude oils from the Middle East showed a significantly reduced response to most inhibitors. The results are discussed in terms of the differences in solubility of the paraffin waxes, and the chemical composition of the crude oils.
Secondly, the influence of a wide range of crude oil properties on the effectiveness of wax inhibitors was investigated by treating seven (7) crude oils of different geographical origin with five (5) wax inhibitors and evaluating their performance to reduce wax deposits in a cold finger experiments. Distinct crude oil behaviors were observed in terms of their responsiveness to the wax inhibitors. Some crude oils were equally responsive to wax inhibitors, while others showed moderate response, and one was not responsive at all. The results are clear examples of the crude oil "specificity", and demonstrate the risks of using model waxy fluids, or even different crude oils, to extrapolate the performance of wax inhibitors. Additives that worked well in model fluids might not work at all in real crude oils.
Lastly, physical properties of crude oils and molecular characteristics derived from high-temperature gas chromatography (HTGC) were used to seek a correlation to wax inhibition performance using chemometrics tools, specifically, principal component analysis (PCA). Preliminary results from the PCA approach indicate that several crude oil properties affect inhibition efficiency. The analysis suggests that the efficiency of the inhibitors studied here increases for crude oils with lower wax appearance temperature, lower pour point and lower carbon number distribution. It could also be inferred that inhibition efficiency was improved in crude oils containing higher amounts of asphaltenes but low wax content.
Recommended Practice for Structural Integrity Management of Floating Offshore Structures – A DeepStar 12401 Product
Authors: Wisch David , Spong Robert 
Published: April 2016

With recent technologies and exploration expanding the commercial viability of many deepwater fields, offshore operators now must contend with ways to keep their aging floating structures on station up to, and in many cases, beyond their original service life. As a result, there is a growing need within industry for a recommended practice focused solely on the Structural Integrity Management (SIM) of floating structures that provides guidance to operators and engineers in the development and implementation of SIM programs as well as to assess the fitness-for-purpose of a floating system over the original service life and beyond. Recognizing this need, DeepStar® initiated Project 12401 to develop a draft SIM Recommended Practice (RP) for floating offshore structures that covers hull, mooring, topsides structures and marine systems (e.g., ballast systems, propulsion, etc.). DeepStar® is a joint industry technology development project focused on advancing the technologies to meet its members’ deepwater business needs to deliver increased production and reserves. Members are comprised of various international oil and gas operators.
This paper describes the content and benefits of this new draft RP. The development process and required components of a floating structure SIM program are defined within the RP, which are currently not available in other industry RPs. Additionally, the overall implementation elements (i.e., Data, Evaluation, Strategy and Program) and associated processes required to manage a floating structure's integrity and confirm fitness-for-purpose over the service life (i.e., from commissioning to decommissioning) are covered. This includes assessment initiators (e.g., triggers for assessments) and a stepwise assessment process used to demonstrate the fitness of a floating structure. Guidance on assessing the fitness and viability of a floating structure for continued service beyond its original service life (sometimes referred to as "life extension") is also contained within the RP and described within this paper.
Advances in Model Scale Testing of Floating Offshore Wind Turbines Utilizing the W2 Wind/Wave Basin
Authors: Fowler Matthew J. , Goupee Andrew J. , Viselli Anthony M. 
Published: April 2016

Abstract
Increased interest in floating offshore wind turbine (FOWT) technology has stimulated the development of new testing facilities and techniques to support the design of these structures. This paper presents some specific challenges of testing FOWTs and how these requirements have driven the development of wind/wave basins capable of providing both high quality wind and wave environments necessary to test these structures. Previous experience by the University of Maine (UMaine) and others as part of the DeepCwind Consortium in testing 1/50th-scale FOWTs at the Maritime Research Institute Netherlands (MARIN) Offshore Basin has supported the development of UMaine's Harold Alfond W2 Ocean Engineering Laboratory (W2), which includes a movable, open-jet wind machine specifically designed to provide a high quality wind field for testing FOWTs. A calibration testing campaign of this newly constructed facility will recreate a subset of the tests performed at MARIN. The new test campaign will contain system identification, wind turbine performance characterization, wave only, wind only, and combined wind/wave test cases utilizing both regular and irregular wave specifications. This paper will focus on the initial phase of this campaign which includes select system identification and regular wave tests. The test specimen is the same used in the original test program performed at MARIN and consists of the 1/50th-scale model semi-submersible along with the 1/50th-scale model version of the National Renewable Energy Laboratory (NREL) 5MW Reference Wind Turbine. Results from the new test campaign are studied and compared with the data from the 2011 MARIN test. Differences in data collection methods, basin geometry, model specifics and test methods were expected and are discussed for this initial phase. In particular, differences in the basin geometry necessitate development of a truncated mooring system to emulate the response of the full mooring system used at MARIN. The implications of utilizing this method are discussed as well as additional areas of future work to be completed in subsequent phases of the validation test campaign.
Progress in the Development of Test Methods and Flexible Composite Risers for 3000 m Water Depths
Authors: Anderson T. A. , Fang B. , Attia M. , Jha V. , Dodds N. , Finch D. , Latto J. 
Published: April 2016

Abstract
The primary aim of the present development program is to enhance access to deepwater fields in the Gulf of Mexico, Brazil, and West Africa by reducing system, transportation and installation costs for flexible production pipe technology. To accomplish that goal composite materials are being incorporated in hybrid unbonded flexible pipe structures to enhance their overall system performance and expand the operational design envelope. The use of composite materials enables significant improvements in operating pressures at larger pipe diameters, reduced weight and top tension, and the enhanced resistance to CO2 and H2S drives further improvements in the structural sour service performance and lifespan.
GE Global Research and GE Oil & Gas, with the support of Research Partnership to Secure Energy for America (RPSEA), embarked on a development program to qualify flexible pipe with an internal diameter of greater than seven inches for ultra-deepwater applications. The concept consists of an optimally engineered combination of metallic and composite reinforcing layer technologies. This hybrid design approach allows the pipe system properties to be tailored to yield the optimal result for any application conditions. The approach offers performance advantages including reduced risk on critical end fitting technology, continuous reinforcement of the liner eliminating discontinuities and local strains by fusing together the reinforcement and liner, superior matrix chemical resistance by using industry proven thermoplastic materials, and a reduced layer count leading to easier inspection.
This paper will provide an overview of the progress made during the collaborative RPSEA program and specifically, will highlight the bespoke testing capabilities developed for the new composite pipe layer. Although there are several individual standards, specifications and Joint Industry Projects (JIP) in relation to composite pipes that address some of the required tests, there remains a general lack of consensus with regard to specific testing standards and understanding of the long term performance, especially considering the variety of composite pipe technologies being developed by the industry. This paper will highlight the results from mid-scale burst testing along with analysis validation, and a bespoke rotating bending fatigue test rig used to assess the bending fatigue of the composite pipe structure. Lastly, progress toward the use of sub-scale tests allied with analysis to more rapidly assess the fatigue life will be discussed.
Impacts of Wind Turbulence on the Performances of a Semisubmersible-Type and a TLP-Type Wind Turbine
Authors: Udoh Ikpoto E. , Zou Jun , Edgar Craig 
Published: April 2016

Abstract
Analysis assumptions in the design of floating offshore wind turbines can lead to inadequate designs that ultimately affect performance and cost of the system. One of the common assumptions made is the use of steady wind fields for analysis and design. In reality, the dynamic components of wind fields, known as wind turbulence, can be significant thus inducing significant responses in the system not captured by the assumption of steady winds. The objective of this study is to investigate the effects of turbulent wind fields on the performances of a semisubmersible-type and a Tension Leg Platform (TLP)-type offshore wind turbine.
The wind turbine implemented in this study is the 5 MW reference turbine developed by the National Renewable Energy Laboratory (NREL) in the U.S. The selected semisubmersible platform has been studied in the Offshore Code Comparison Collaboration Continuation (OC4) project by NREL, while the TLP concept is a three-column TLP developed and sized by Houston Offshore Engineering, an Atkins company. To address the identified concern, the method implemented is a coupled aerodynamic-elastic-hydrodynamic-control approach, which accounts for all important effects in estimating the responses and generated power of the system. Representative load cases with and without wind turbulence are considered to delineate turbulence-induced impacts on the two concepts.
The system characteristic responses, such as nacelle accelerations, towerbase forces, towerbase moments, generated power, and platform motions, are focused on and compared. The extent to which the listed results are affected by wind turbulence depends on the characteristics of each floating platform. Discussions provided in this paper relate the observed responses to the platform characteristics.
Findings of this paper offer significant insight when considering hull form selection. The primary contribution of this work is to increase the depth of understanding on the importance of wind turbulence in the response characteristics of semisubmersible-type and TLP-type wind turbine platforms.
Faitgue Reliability Assessment for Life Extension of Offshore Structures
Authors: Sahasakkul Watsamon , Nguyen Hieu , Sari Ali 
Published: April 2016

Abstract
This study is focused on the prediction of the remaining life of an offshore structure using the fatigue reliability analysis. Our objective is to propose an alternative approach to assess long-term fatigue damage using a reliability analysis for life extension studies of offshore structures. In this approach, hot-spot stress response spectra in the frequency domain, considering stress concentration factors and stress transfer function, are generated using spectral fatigue method. Damage of the hot spots for a given sea state is carried out using products of the hot-spot stress response spectra. For reliability analysis, the limit state for fatigue damage is formed in terms of fatigue damage, fatigue capacity, randomness of environmental data, and other critical parameters of S-N curves. The probability of failure due to long-term fatigue damage is evaluated using reliability methods. The results of long-term reliability of fatigue damage are validated against other approaches such as Monte Carlo simulations.