bluuebunny/crossref_metadata_2025_split huggingface dataset:
Practical Method for Simulating Flotation for Produced Water System Design
Authors: Straw Matt , Fielding David , Kay Edward , Lo Simon , Eppinger Thomas 
Published: April 2019

Abstract
Maintaining produced water quality is a critical environmental target, and legislative requirement, for the oil and gas industry. Design and operation of effective produced water separation systems requires understanding and management of a range of complex multiphase flow phenomena, especially where gas flotation processes are used.
This paper presents a novel modelling approach, using Computational Fluid Dynamics (CFD), developed to simulate gas flotation processes. The approach aims to predict the gas-oil coalescence process using a simple and time-efficient method.
In the flotation process, small gas bubbles, introduced to the produced water, coalesce with the oil droplets present in the water. The combined gas-oil particles have more buoyancy than the oil droplets alone and separate more effectively from the water. While CFD approaches have been applied to improve the design and operation of a wide range of separation and compact and induced-gas flotation systems, it has typically been too technically challenging and time-consuming to attempt to capture the coalescence process involved in flotation in such simulations at a system level. Often, designers and engineers have to make use of general flow characteristics, behaviours and indicators to imply the flotation efficiency of a given design, with many combining simulations and physical testing to provide greater confidence in design and operating decisions.
The approach presented in this work aims to predict the gas flotation process and coalescence efficiency, using a simplified approach by combining multiphase flow simulations, using Simcenter STAR-CCM+, representing both the small oil droplets and the gas bubbles. In the approach, the local concentration of oil droplets in water and in gas is tracked throughout a given produced water system. Oil is transferred between the water and the gas phases representing the coalescence process. The rate of transfer is governed by a model which depends on local flow conditions such as bubble size, probability of adhering and detaching and surface area of gas bubbles available for coalescence.
The approach is applicable to both compact flotation and induced-gas flotation systems and the results of the approach give direct comparisons of oil in water concentration both through a system and in the water exiting. The oil concentration leaving the vessel is reported, thus directly quantifying the effectiveness of the vessel; this is an improvement over other approaches using CFD where flow characteristics are used as proxies to infer the separation effectiveness. In using flow characterisctics alone there is potential for critical aspects or counter-intuitive mechanisms to mislead engineers.
It is hoped that the method presented will enable engineers and designers involved in the development, design and operation of produced water systems to more-fully understand both the complex fluid mechanics and efficiency of the flotation processes.
The Reduced-Draft Spar: A Novel Cost-Effective Concept for Floating Offshore Wind Turbines
Authors: Guzmán Santiago de , Taboada Miguel Jesús , Pombo Albino , Martín Rafael , Bezunartea Ana , Knights-Cooper Andy , Moreu Jaime 
Published: April 2019

Abstract
This paper describes the conceptual design and estimates the CAPEX breakdown of a novel floater type for offshore wind turbines: the Reduced-Draft Spar (RDS). This floater, which resembles a GBS although it is in essence a spar, has excellent seakeeping at a reduced draft.
Aiming at reducing the CAPEX, the RDS design allows the installation of the wind turbine at the manufacturing site. Furthermore, no auxiliary means are required to provide stability during towing and in-place installation (mooring and electric hook-up, and ballasting to the operational draft). It also promotes the use of structural concrete and cost-effective high-density ballast for its construction. In addition, the whole concept benefits from the implementation of an Active Ballast System (ABS) to compensate the mean tilt angle while operating.
An extensive model test campaign was carried out in summer 2018 at INTA-CEHIPAR model basin to validate the concept. The tests scope was focused on calibrating a state-of-the-art numerical hydrodynamic model for further stages of development. An 8MW RDS model, with a scale factor of 1:50 and a 3-line spread mooring system, was tested in Transport and Installation (T&I), operational and survival conditions to assess the concept feasibility. The ABS was simulated using pre-calibrated counteracting weights. Stability during T&I was also checked.
In addition, the unit CAPEX was estimated and compared to equivalent semi and spar units made of steel. The RDS can operate at intermediate water depths (60 to 80 m, where spars cannot) and deep waters, and also avoids the use of expensive auxiliary means for T&I. The results from the model tests confirm a dynamic behavior of the RDS similar to that of classic spars, which is beneficial for the offshore WT. Regarding the CAPEX, estimations indicate relevant savings compared to classic spars or semis.
Although it is a large massive unit, the use of concrete combined with heavy ballast makes the concept feasible. Due to the ABS, the required platform's size is smaller and the fatigue life of the WT components increases. Furthermore, an adequate ABS control system increases the net energy production since the energy consumption is negligible compared to the extra generated power. The use of civil construction manufacturing technologies such as floating docks and assemble of pre-manufactured parts leads to major CAPEX savings.
The US coast has a huge offshore wind energy resource at water depths greater than 60m, where the RDS floating concept has a promising future. The concept could be used as well in the Offshore Oil& Gas.
Seabed Seismic Motion in Presence of Seismic Induced In-Profile Liquefaction
Authors: Bertalot Daniele , Corciulo Simone 
Published: April 2019

Abstract
Cyclic loading caused by earthquake in sandy soils often leads to the development of positive pore pressures. In extreme conditions, the pore pressure may increase until reaching a state of zero effective stress associated with a dramatic reduction of the soil shear stiffness and strength. Even when liquefiable soils are found at depth, and capped by a non-liquefiable crust, once liquefied they can act as a seismic isolator, significantly modifying both amplitude and frequency content of the vertically propagating shear waves. As a result, seabed seismic motions at offshore sites characterized by the presence of liquefiable layers within the soil stratigraphy may change considerably with respect to a non-liquefied scenario. Non-linear Seismic Site Response Analyses (SSRA) are often used for site-specific evaluation of seismic input for offshore projects. Severe earthquake motions induce non-linear soil response associated with significant stiffness reduction for soft soils. The hysteretic non-linear soil behavior leads to modifications in terms of magnitude and frequency content compared to the postulated stiff soil input. This is even more important where pore pressure build-up and liquefaction may occur, leading to further modification of the seismic accelerations at mudline. However, standard industry practice consists in performing total stress SSRA that are not able to model the softening response in presence of liquefiable soil layers. This paper compares the seabed seismic motion assessed by means of total and effective stress SSRA in order to evaluate the effect of the soil stiffness degradation in liquefied layers within the soil profile, building upon the findings of Ardoino et al. (2015), who observed in-profile liquefaction to have a limited effect on mudline response spectrum. In particular, it is shown how modelling methodologies able to replicate the transient nature of excess pore pressure build-up during earthquake excitation (i.e. time-domain analyses), are better suited to capture seismic motion modifications in presence of in-profile liquefaction, with respect to response spectrum analyses. The effects of deep foundations embedded across the liquefied layers, on the propagation of the seismic motion, is also investigated and discussed.
Offshore Liquefied Natural Gas LNG and Monetization
Authors: Alabi Femi Adeoye , Awotunde Timothy Oluwarotimi , David Joseph Olusegun 
Published: April 2019

Abstract
The growing global energy demand and the ecological advantages of low ozone depleting substance resulting from combustion of the natural gas products leads to consideration of economic, practical innovations of transporting the gas. The alternatives of marketing the unused gas include regional or local markets, projects of combined commodity and the export markets. Natural gas has been transported securely, dependably, and financially utilizing pipeline. This paper addresses the issue of Offshore LNG and Monetization with special attention to Supply Chain.
In this particular project, the writer will be examining Stranded Offshore gas and Supply Chain, to demonstrate Monetization. Legislations and policies will be juxtaposed them against the upstream sector and downstream sector, with the aim of revealing the formerly misunderstood connections between supply chain and monetization. The question of Offshore LNG and Monetization have been greatly debated in the Gas and Energy field, with organizationsarguing Monetization and Supply Chain. However, these works have not adequately addressed the issue of Offshore LNG and Monetization with the supply chain philosophies.
Various solutions for mismanaged stranded gas holds are presently being created and contemplated for commercialization. In the meantime, for the past decades, only the LNG industry (Liquefied Natural Gas) has efficiently conveyed many remote natural gas reserves to the various gas markets which are not reachable through pipelines, such as South Korea and Japan. In conclusion, by closely analyzing monetization and Offshore LNG, this project brings a new understanding of the rarely acknowledged/little recognized/neglected issue of Supply Chain Management. In spite of being a standout amongst the most copious sources of energy on earth, more than thirty-three percent of international natural gas fields stay unused and cannot be conveyed to the market monetarily.
As far back as decades, it is evident that large amounts of fresh gas saves are certainly not the only things that are placed strategically. Consideration has been directed to more segregated vast gas reservoir that was earlier thought of as being excessively remote and impossible to develop. Once a typical industry works on, flaring is currently broadly debilitated, and numerous nations including Norway and Nigeria, that are coming up with emission or anti-flaring taxes and policies to discourage gas wastage.
Soil Classification and Evaluation of Preconsolidation Stress of Atlantic Outer Continental Shelf OCS Sediments from Oedometer and Cone Penetration Testing
Authors: Long Xiaoyan , Tucker Greg , Gibbs Paul , Westgate Zack , Diaz Alberto Troya , Senanayake Asitha 
Published: April 2019

Abstract
The geotechnical site characterization process typically begins with an assessment of the soil lithology, the in situ stress state, and the geostatic stress history of the formation, which involves identification of soil types and an evaluation of the preconsolidation, or effective yield, stress. The preconsolidation stress is defined as the maximum past stress physically and/or mechanically applied to the soil, representing the demarcation between normally consolidated (NC) and overconsolidated (OC) states.
This paper presents an assessment of the preconsolidation stress of Atlantic Outer Continental Shelf (OCS) sediments within the zone of influence for offshore renewable wind turbine foundations, based on laboratory oedometer test data and cone penetration test (CPTu) data. Atlantic OCS sediments comprise a complex layering of clays, sands, and silts, classified using physical (textural) characteristics, including visual description, grain size distribution, and soil plasticity-based or CPTu data-based soil behavior type (SBT) charts.
Soil classification for a variety of OCS sediment types from SBT charts, the Unified Soil Classification System (USCS), and ISO standard 14688-2 (2018) is compared and described. Predicted preconsolidation stresses are compared across several commonly used industry methods, and prediction accuracies are discussed in the context of soil type, minerology, and microstructure. Guidance is provided on appropriate site investigation (SI) techniques to allow characterization of these influential properties.
Sand Control Completions for Raven Field in Egypt
Authors: Tahirov Tahir , El-Wakeel Wael , Mohiuldin Ghulam , Whaley Kevin , Jackson Phillip , Olinger Michael , Mansour Mohamed , Elshafaie Ibrahim 
Published: April 2019

This paper presents the results of design and field execution of sand control completions for Raven High Pressure High Temperature (HPHT) gas field in Egypt. The reservoir contains stacked channel formation sands, that require sand control completions. The completions design is complicated due to combination of sand control and HPHT environment where industry has limited experience. The selected completions type was an Open Hole Gravel Pack (OHGP) with a pre-drilled liner. A series of lab testing has been conducted to design and qualify completions fluids. The lab test program included formation damage tests, shale stability tests under dynamic and static conditions, materials and fluids compatibility tests and others. The downhole completions hardware was specifically designed to allow effective displacement from oil based mud to completion brine fluid with subsequent gravel pack placement. The circulating gravel pack placement technique was selected using Cesium Formate brine as a gravel carrier fluid.The field installation campaign of the selected completions method is currently underway with 4 wells already successfully being completed. All completed wells demonstrated excellent well performance results with very low completions skin. The well flow-back and test results exceeded expectations, indicating the entire reservoir sand was contributing to flow, demonstrated greater than predicted Productivity Index (PI) with minimal skin damage. Sand control integrity was achieved with full gravel pack efficiency.
Practice of Riser-Soil Interactions at Touch Down Zones for Steel Catenary Risers
Authors: Chen Jinbo , Newlin Jason A. , Luo Meng , Zhang Heping , Hadley Chris J. , Hu Shuang 
Published: April 2019

AbstractRiser-soil interactions have significant influence on the fatigue assessment of steel catenary risers (SCRs) near the touch down zones (TDZs), and can be critical in realizing a competitive SCR design and in extending a SCR design life. The motivation of the paper is to share the proprietary model test data and research/ design experience accumulated over the past three decades on the riser-soil interactions with the riser engineering community in order to deepen the understanding of this complex problem and to realize economical SCR designs. The objectives are (i) to present a fully nonlinear hysteresis model that captures the loading history of the riser-soil interactions at TDZs in the vertical direction for SCRs, and (ii) to propose a simplified equivalent linear elastic vertical stiffness for SCRs at TDZs for quick fatigue assessments. The paper begins with the mathematical formulation of the nonlinear model and the equivalent linear model for riser-soil interactions. Then the proposed model is verified through the consistent predictions from time-domain and frequency-domain simulations of an SCR from a Tension Leg Platform (TLP), the close agreement between the proposed model predictions and small scale pipe-soil interaction model test results, reduced scale sectional SCR model test results, and the latest study in the literature.
Aasta Hansteen Spar FPSO Substructure, Mooring, Riser and Systems Design
Authors: Sablok Anil , Kim Jang , Tallavajhula Sudhakar , Wang Feng , Dalane Oddgeir , Kristoffer Høyem Aronsen , Kippenes Jon 
Published: April 2019

Abstract
Aasta Hansteen, located in 1300m water depth, is the first deep water field on the Norwegian continental shelf developed with a surface platform concept. It is in the Norwegian Sea and developed using a Truss Spar FPSO. It is the world's largest Spar platform substructure facilitated for continuous personnel entrance and with a large volume of condensate storage in the hull that is offloaded to a shuttle tanker. It is the first floating platform in a North Sea/Norwegian Sea harsh environment with steel catenary risers (SCR). It is the first Spar designed to NORSOK and other Norwegian regulations. The platform was made ready with platform mooring chain and topsides installed by floatover in a fjord before being towed vertically to the field.
Symbiotic Autonomy for Deep-Water Survey
Authors: Ziegwied Andrew Ziegwied Theodore 
Published: April 2019

AbstractCoupling Long-Range Autonomous Underwater Vehicles (LRAUVs) with Unmanned Surface Vehicles (USVs) solves two of the key challenges associated with LRAUV missions: lack of real-time communication with the underwater asset and unbounded navigational error growth from dead reckoning. The coupling of LRAUVs and USVs effectively transforms the capabilities and accuracy of the LRAUV survey.A premier supplier of Unmanned and Autonomous Marine Systems led this development project working alongside a world-leading research center and developer of LRAUV systems. These two organizations were assisted by a leading developer of subsea acoustic positioning, communications and sonar systems, and a developer of software solutions for autonomous systems.The system architecture enables the USV to provide regular position updates to the LRAUV, removing the need for the LRAUV to surface from depth to update its internally calculated position. This cooperative localization scheme increases the efficiency and accuracy of LRAUV survey while reducing cost. The combination of the high-accuracy sonar systems on the LRAUV transiting close to the seabed and accurate position updates from the USV provides game-changing solutions for deep water surveys and Exclusive Economic Zone (EEZ) mapping globally.Due to the endurance and autonomy, this combination also allows for the possibility of executing remote subsea operations from a shore-based location. Eliminating the need for large ships to accompany the LRAUV significantly reduces data acquisition costs.The USV communicates with the LRAUV through two key methods: acoustics to provide short mission updates and positioning information, and optical communication technology to enable the system to upload the data from the survey sensors. With the data uploaded to the USV, it is then possible for the USV to process the data to enable summary data to be passed back through satellite or radio communications to a control center. In situations where data may indicate where gaps occur, or further investigation is required, an updated mission plan can be transmitted from the control center to the USV and then to the LRAUV. As onboard data processing techniques improve, the USV can be used to adaptively update the LRAUV's mission without human intervention.This transition to autonomy will save costs, reduce risk, and increase flexibility across a range of applications, including mine countermeasures, weapons testing, hydrography, environmental science, security, and surveillance.
Developing and Fielding Perforating Systems: A Comparison in High-Pressure Wells
Authors: Robey Richard , Suire David , Grove Brenden 
Published: April 2019

Abstract
This paper presents an outline for the development and deployment of three perforating systems to address several needs of high pressure (HP) US Gulf of Mexico wells. A case study is presented, highlighting the key differences between systems, and includes comparisons between data obtained during engineering development and field deployment phases
During the development phase rigorous testing was conducted in line with API RP 19B sections 2, 3.14, and 5 to characterize the perforating systems' performance. These tests were executed to assess charge performance, system pressure rating at downhole conditions, and debris characteristics at surface conditions. Following the development testing, the systems were fielded with wellbore pressure being captured on downhole gauges to assess the perforating event response comparing to pre-deployment models. Additionally, wellbore debris recovered post-perforating was evaluated on surface.
The first system was to support an HP application that requires high flow area in heavy wall casing. This was the platform for other less traditional systems to expand upon. Utilizing high shot density and big hole (BH) charges, this system was tested to provide a system rating of up to 30 ksi at 425°F while retaining fishability in heavy wall casing. For this system, wellbore effects from perforating, such as dynamic underbalance and recovered debris, are qualitatively aligned with existing perforators.
The second system was optimized to control dynamic transient loading on the perforating string and minimize debris in HP environments. This meant the system was required to fit into a strategy of lowering dynamic structural loads on the workstring created during perforating. The system was designed to affect the pressure interactions among the gun internals, wellbore, and the formation, and control the amount of formation material inflow and debris produced by perforating. This perforating system was developed, qualified, and successfully fielded in multiple wells without any operational issues.
The third system provides increased formation penetration depth without sacrificing shot density. By using deep penetrating (DP) charges, this system is can provide penetration past drilling damage or mitigate higher formation strengths encountered at greater depths in some HP US GoM reservoirs, thus providing operators improved connectivity to the formation.
Evaluating perforating system performance, not only with lab testing but with field-gathered data, is crucial to closing the development loop for HP applications where testing is not practical due to both scale and replication of wellbore conditions. In deployment, the well conditions for the systems were analogous, highlighting the differences in data, thus providing a more complete background for operators to assess the suitability of these systems in HP applications and evaluate their perforating method to maximize production.