bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing SNMR model resolution by selecting an optimum combination of pulse moments, stacking, and gating
Authors: Dalgaard E. , Müller‐Petke M. , Auken E. 
Published: November 2016

ABSTRACTFor the surface nuclear magnetic resonance sounding method, we investigate the tradeoff between stacking and the number of different pulse moments by analyzing the a posteriori model covariance matrix. It is shown that a better determination of the model parameters is obtained by increasing the number of pulse moments compared with increasing the stack size until a certain point. From this point, the determination does not change. A distribution of pulse moments based on the resolution of the surface nuclear magnetic resonance sounding kernel is calculated and compared with a standard logarithmic distribution. Our results show that the resolution‐derived distribution performs better overall, and the logarithmic distribution is only slightly better for very shallow layers. Finally, we use gating of the free induction decays in order to suppress noise, and we show that, by using a logarithmic distribution of gates, we obtain maximum resolution of the models by only seven gates per decay.
Suitable real‐time monitoring of the aerobic biodegradation of toluene in contaminated sand by spectral induced polarization measurements and CO2 analyses
Authors: Noel Cécile , Gourry Jean‐Christophe , Deparis Jacques , Ignatiadis Ioannis , Battaglia‐Brunet Fabienne , Guimbaud Christophe 
Published: November 2016

ABSTRACTHydrocarbons commonly contaminate aquifers and, in certain cases, can be successfully treated through biodegradation. Biodegradation is an effective technique for cleaning up pollution by enhancing pollutant‐degrading bacteria in situ. However, in situ sampling for monitoring processes occurring into the ground during the treatment is expensive and invasive. In this article, an alternative method was tested. Spectral Induced Polarization (SIP) was combined with gas analyses, CO2 concentration and its carbon isotopic ratio, to monitor toluene aerobic biodegradation in laboratory columns. Microbial activity was characterized by an evolution of the SIP response in correlation with a CO2 production with the same carbon isotope signature as toluene. The spectral induced polarization response followed the variations of bacterial activity and displayed a phase shift up to 15 mrad. These results support the feasibility of using geophysical measurements, supported by CO2 analyses, to monitor in situ hydrocarbon biodegradation, and they are proving to be highly promising for real field scale monitoring.
3D inversion of irregular gridded 2D electrical resistivity tomography lines: Application to sinkhole mapping at the Island of Corfu (West Greece)
Authors: Kim Jung-Ho , Tsourlos Panagiotis , Karmis Petros , Vargemezis George , Yi Myeong‐Jong 
Published: November 2016

ABSTRACTWe study the case of the combined interpretation of irregularly gridded 2D electrical resistivity tomography lines. A 3D inversion algorithm was specially modified to accommodate the full 3D processing of such lines. The chosen approach uses a dense structured mesh and a flexible parameter design scheme. Tests with synthetic data show that full 3D inversion results are significantly improved when compared with the equivalent quasi‐3D imaging of the 2D inversion results. It is also shown that 3D inversion results can provide correct location and shape information about targets that are not directly located under the measured lines. The scheme was tested with real data from a site in the northern part of the Corfu Island (West Greece) where a large number of irregular gridded 2D electrical resistivity tomography lines were collected in order to map sinkholes related to gypsum. The 3D inverted images provide important information about the structure of the existing sinkholes and the potential sinkhole generation mechanism. Overall, the possibility of 3D interpretation of irregularly gridded lines is not only important for obtaining better subsurface images but also allows a more flexible and practical design of electrical resistivity tomography field surveys.
Arctic Monitoring: A Remote Sensing Analysis of Former Wellsites
Authors: Brunke Suzanne , Dacre Cynthia , Oldak Anna , Mercer Sean , Rockwell Greg , Bakker Adrian , Bertrand John 
Published: November 2016

Abstract
Numerous exploratory wellsites were established in Canada's Arctic during the second half of the 20th century and were subsequently closed. Due to the logistic challenges of monitoring such sites through conventional approaches, the operator engaged the service provider to conduct a study using remote sensing techniques and high-resolution optical imagery on several closed wellsites (7 sites on-shore) in the Mackenzie River Delta of Northwest Territories, Canada. The project focused on demonstrating the ability to track changes in site conditions (retrospectively), distinguishing cyclic from progressive changes, and evaluating the potential cost for routine site monitoring at different intervals. Available sources of optical imagery were used; from 1 m IKONOS to 0.5 m WorldView-2, with dates ranging from 2002 through 2014. The optical analysis utilized the Normalized Difference Vegetation Index (NDVI) ratio of near infrared and red bands to provide an index of biomass density. A variety of processing techniques and analyses were performed that focused on four major areas: relative water levels, vegetation health, condition of infrastructure, and the proximity of nearby receptors. Synthetic Aperture Radar (SAR) imagery from RADARSAT-2 was also used successfully to detect pilings that were not visible in the optical imagery.
Case Studies in Application of Design of Experiments Methodology to Ice Basin Testing
Authors: Fenz D. M. , Foltz R. R. , Sarlis A. A. , Younan A. H. , Jochmann P. , Schroeder C. , Myland D. , Ziemer G. , Spencer D. 
Published: November 2016

Abstract
This paper describes four case studies highlighting applications of Design of Experiments (DOE) methodology in ice basin testing. The case studies are (1) an investigation of methods for model ice ridge preparation and property testing, (2) managed first-year ridge interaction with an axisymmetric floater, (3) interaction of first-year ridges with a multi-leg GBS and (4) towing of a gravity-based structure and axisymmetric floater in ice. These experiments illustrate a different approach to ice basin testing. Rather than trying to reproduce natural conditions and scale up loads, critical design scenarios are isolated and DOE methodology is used to determine the most influential parameters on response quantities of interest.
A 3-D Random Lattice Model of Sea Ice
Authors: van den Berg Marnix 
Published: November 2016

AbstractThis paper demonstrates the application of a 3-D random lattice model based on Voronoi tessellation. The model may be applicable in a wide range of sea ice modelling scenarios. Lattice models based on Voronoi tessellation give accurate results in fracture modelling of brittle, inhomogeneous, and/or polycrystalline materials such as concrete and rock. Therefore, our hypothesis is that a similar model might also yield good results in the modelling of sea ice failure. This paper demonstrates that a random lattice model is capable of predicting the deformation of an ice plate on a Winkler foundation. Additionally, it shows a range of other possible applications. Most notably, an application of the model in numerical ice ridge generation is demonstrated.
Common Operational Picture COP Requirements for Floating Drilling in Pack Ice
Authors: Shafrova Svetlana , Holub Curtis , Harris Matthew , Cheng Tao , Matskevitch Dmitri , Foltz Raymond , Mitchell Douglas 
Published: November 2016

AbstractA Common Operational Picture (COP) can generally be described as a system of hardware and software that produces a shared display of information to facilitate situational awareness and decision making. A brief history of the development and use of COP technology in Arctic operations is provided. Experience and learnings from ExxonMobil's research into the use of COPs in ice management and Arctic floating drilling is described. Experience gained from simulations, desktop studies, and field observations is used to frame preliminary functional requirements for such technology needed for future Arctic floating drilling operations in high concentration ice. The COP must facilitate the planning and execution of complex and remote operations with many geographically distributed assets (e.g., drilling rig; icebreakers; shore base; manned or unmanned aviation) and stakeholders (e.g., icebreaker captains, drilling management, ice analysts, weather forecasters) at times communicating over limited bandwidth channels. The COP will serve to collect, store, communicate, and display the necessary data and information. The role of COP components (e.g., databases; communication network, displays) is described and functional requirements are outlined.
Passive Particle Continuum Ice Model for Efficient Load Estimation
Authors: Berg Joris van den 
Published: November 2016

Abstract
Based on ideas taken from geophysical models, a 2D continuum ice flow model is derived and tested. The model can be used to simulate ice loads on a vessel. The model aims to fill the gap between strictly empirical models excluding load variations and a fully 6D solid bodies approach that is typically too costly for real time simulation and computation of long term statistics. In addition it could be used to obtain the far field solution for use in combination with more detailed models close to the ship.
To guarantee conservation of mass and momentum, a 2D finite volume approach is used as a starting point. Instead of a flux solver, passive tracer particles are used. These include collision handling at the finite volume cell interfaces and with line segments representing any vessel hull. The passive tracer particles carry mass and momentum from one finite volume cell to another. Model extensions for relative current drag and friction can be added on the cell averaged level.
The resulting 2D hybrid continuum model yields promising first results: The computational speed is sufficient to simulate large ice fields (&gt;5km squared, &gt;5,000 ice floes) at more than real time speed.Qualitatively, the ice flow is realistic and the flow properties can be tuned using relatively straightforward parameters.
A 3D Time-Domain Model for Iceberg Impacts with Offshore Platforms and Subsea Equipment
Authors: Fuglem Mark , Younan Adel 
Published: November 2016

Abstract
When designing oil and gas platforms for offshore arctic and subarctic regions, operators may need to consider the influence of iceberg impacts on optimal structure configuration and ice strengthening requirements. Icebergs have complex and varied shapes, are mostly underwater and are usually moving in currents and waves. Previous iceberg profiles developed from sonar profiles and above water measurements have varying limitations in accuracy, necessitating approximations in modeling both the overall and local shape of the icebergs. A field program was conducted to obtain high resolution full three dimensional (3D) iceberg profiles that allow for detailed modeling of icebergs. Following the field program, a number of studies were conducted to utilize this data to develop improved tools both for calculating design iceberg impact loads for offshore structures and for improving ice management. One of these studies, described here, entails development of a full 3D timedomain simulation model for icebergs impacting fixed and floating platforms in 6 and 12 degrees of freedom (DOF) respectively. A key requirement of the model is that existing scale dependent models for global ice crushing failure pressure can be incorporated. The main objective in developing the model was to provide a tool for evaluating specific iceberg impact scenarios that considers 3D effects and requires fewer assumptions regarding interaction mechanics than previous methods.
In this paper, the basic framework of the 3D time-domain model is described, and initial model results are presented for several example applications: icebergs impacting a cylindrical GBS, a stepped cylindrical GBS and a moored spar floating production unit (FPU), the probability of iceberg pinnacles impacting a platform topsides, and subsea interactions. For the cylindrical Gravity Base Structure (GBS), sensitivity analyses are presented for ice strength, friction, drag coefficient, damping coefficients, platform diameter and iceberg velocity.
Numerical Evaluation of Permafrost Thawing in Arctic Pipelines and Mitigation Strategies
Authors: Abdalla Basel A. , Mei Haixia , McKinnon Colin , Gaffard Vincent 
Published: November 2016

Abstract
Permafrost thaw induced settlement is a major concern for pipeline design and operation in the Arctic region. For a buried warm pipeline in permafrost, heat losses can thaw the frozen water in the surrounding soil and create a thaw bulb around the pipeline. The underlying soil will then settle and consequently cause settlement of the supported pipeline. Uneven settlement along the pipeline will induce pipeline bending, and may even damage pipeline during operation if resulting strains exceed allowable values. Using finite element analyses to predict pipeline behavior due to permafrost thaw induced settlement can provide guidance on pipeline engineering considerations such as pipeline design, installation and mitigation.
The authors previously presented a finite element model (FEM) developed to study the thaw induced settlement and stresses in pipeline by sequentially coupling a 2D heat transfer model and a 3D soil consolidation/soil-pipe interaction model. The heat transfer and thaw settlement were validated by comparing the numerical output with respective analytical solutions. As a continuation of the FEM development, a three-dimensional (3D) fully coupled model to simulate heat transfer and soil consolidation is developed in this paper. This model solves all field equations simultaneously, including temperature, pore pressure and displacement variables. Heat transfer process can be continuously updated as soil consolidation and pipeline settlement occur. Conclusively, the 3D fully coupled model can capture the transient behaviour and interaction between heat transfer, soil consolidation, and pipeline deformation, and simulate the involved mechanisms more realistically. The 3D fully coupled model is compared with the verified sequentially coupled model.
Thermosyphons are then implemented into the fully coupled model to mitigate thaw induced settlement. The effects of thermosyphons on thaw bulb growth around warm pipe and thaw induced pipe settlement are studied.
Steel Lazy Wave Riser with Tether for FPSO with Dis-Connectable Turret for Iceberg Conditions
Authors: Karunakaran Daniel , Frønsdal Magne 
Published: November 2016

Abstract
Recently turret-Moored FPSOs have been used in many deep water developments worldwide, with consideration of dis-connectable turrets for harsh environment with iceberg conditions. This trend makes the interactions between FPSO and risers system more important. Further, Steel Lazy Wave Risers (SLWR), which is a compliant variant of the mostly commonly used Steel Catenary Risers (SCR), is becoming an attractive riser option.
The paper provides a review of two riser systems that can be considered for turret-moored FPSOs, and specific emphasis on Steel Lazy Wave Risers. A detailed case study of Steel Lazy Wave Risers for a typical turret moored FPSO with dis-connectable turret is presented. The design drivers are; to reduce the turret pay load, especially in disconnected condition, the selected riser system should have minimum tension variation so that the disconnected turret is stable and an optimum installed overall cost of the system. To achieve the design objectives an improvised Steel Lazy Wave Riser configuration called "Tethered Steel Lazy Wave Risers" (TSLWR) is developed.
Pros and cons for TSLWR are discussed, with consideration of the particular challenges of turretmoored FPSOs with large floater motions, hang-off geometry constraints at turret, hang-off loads, riser interferences, risers pre-installation, and turret disconnection constraints.
Optimization Methods for Arctic Pipeline Route Selection
Authors: Devine Christine A. , Haneberg William C. 
Published: November 2016

Abstract
As arctic regions become more accessible for oil and gas exploration and development, the need for subsea export pipelines and flowlines will continue to grow. To reduce risks to the pipeline from hazards of natural or geologic origin, it is critical to consider a more sophisticated approach to route selection compared to traditional manual routing practices based on only the shortest length of pipe or connectivity to existing infrastructure. Arctic environments have unique geologic complexities compared to other types of subsea environments. It is important to identify and avoid or mitigate significant hazards such as ice gouges, strudel scours, or permafrost upheaval zones for subsea pipeline routes in arctic environments. In this paper, we demonstrate a workflow to identify and map multiple geohazards, incorporate pipeline-related criteria, classify and weight features based on their inferred risk to a subsea pipeline, develop a composite map of hazards, and perform GIS-based, leastcost pipeline routing techniques to produce the optimal pipeline route options. This approach has been used in deepwater and shallow water settings around the world. We will demonstrate the advantages of following this methodology using multibeam echosounder (MBES) bathymetry data from an arctic location to illustrate the approach for a hypothetical pipeline project in the early stages of development.
Optimizing Geochemical and Sediment Sampling in Frontier Areas by Reviewing Past Projects and Analyzing the Benefits of Introducing New Technologies and Practices
Authors: Carey Nigel , De Coster Molly , Silliman Al , Carter James 
Published: November 2016

Abstract
Due to the large geographical areas typically associated with frontier regions, the need to enhance techniques for gathering information on petroleum systems and prospect charge is critical to ensure efficient and accurate results. Small changes in efficiencies of acquisition techniques and use of ever improving technology can significantly improve the chances of success.
The results from a 2015 geochemical sampling program offshore Labrador and Newfoundland were reviewed, to determine areas of improvement and efficiency for future work in this and other frontier areas. Seismic data acquired offshore Newfoundland and Labrador plus surficial satellite seep mapping hinted at active petroleum systems and thus a need for a geochemical survey to assess these was determined. Evaluated areas were divided into two groups, one to identify regional petroleum systems and the other to reduce prospect charge risk. Core samples, heatflow and bathymetry were among the data collected.
Using the concept of 'intelligent sampling' the authors are developing systems and procedures to ensure efficiency and improve the chances of analytical success. Dedicated vessels with DP systems are utilized, complete with a full range of multi-beam sonars, sub-bottom profilers, dedicated launch and recovery systems, and sub-surface positioning to ensure coring accuracy. Further innovations included core barrel mounted cameras and coring rope load monitoring.
Based on the 2015 survey, modified approaches are proposed to improve sample acquisition, many of which are being implemented in the 2016 survey:core recovery (ensure cores penetrate below the biogenic zone) with revisions to the drop core assembly design;evaluation of appropriate coring methods (gravity, piston and vibro);new technologies for live slick sampling (traditionally difficult in areas of rough weather or sea conditions) are analysed with oil detection radars and seaborne/airborne drones;methods to reduce probability of sample contamination; and,best practice storage methods to meet the needs of the variety of analytical methods proposed.
A Numerical Study of Interaction Between Ice Particles and Complex Ship Structures
Authors: Seo Dong Cheol , Pallard Robert 
Published: November 2016

AbstractThis paper describes a numerical method of ship-ice interaction. Identifying an operational risk to an ice breaking vessel such as serious interference or sudden efficiency reduction by ice is necessary at early design stage. CFD-DEM coupled approach can be used for this prediction. Combining two numerical approaches, free floating ice particles can interact with the surrounding fluid as well as the rigid hull surface effectively. Ship-ice interaction becomes more complicated around the stern area considering the swirling flow of the propulsion device and the complex hull appendages. Using CFD-DEM method, simulation of ship-ice interaction during the astern operation was carried out. To evaluate the simulation performance, three example cases were conducted. The first and second case is the astern operation with/without the propeller action. For reducing the computational load, a virtual disc model for the propeller action is selected. Then, a simple sensitivity analysis on the ice friction coefficient was carried out to verify if the friction model is working appropriately. CFD-DEM simulation provides a promising result showing a similar ice jamming and pileup pattern with the physical model test. The suggested method can help to understand the ice movement effectively including the hydrodynamic force and the contact dynamics together.