bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suction Pile Allowable Suction Pressure Envelopes Based on Soil Failure and Structural Buckling
Authors: Yuan-Hung Kuo , Bo-Siou Wei 
Published: April 2015

Abstract
This study develops the allowable suction pressure envelopes using applicable industrial codes for different suction pile sizes at various penetration depths. In addition to the industrial codes, 3D nonlinear finite element analysis (FEA) utilizing plate buckling techniques is carried out for comparisons. Traditionally, the suction pile design has considered very comprehensive soil failure mechanisms in general practice. However, the structural plate buckling criteria for suction pile with large D/t ratios are not well defined to reflect the current industrial codes and standards. This paper performs extensive study to investigate the buckling strength of suction piles with various D/t ratios using different industrial codes and standards. This study also proposes the 3D nonlinear FEA including the geometric and material nonlinearity and using the plate buckling technique in order to predict the buckling strength for piles with various D/t ratios. The above approaches can provide thorough comparisons among different code requirements and FEA results. After suction pile's self-penetration, the initial suction pressure required to mobilize the force penetration can be critical for pile shell buckling, especially for the large D/t and long pile. This required suction pressure due to moderate soil setup and static friction is briefly discussed in this paper. Based on this study, different codes and standards suggest different buckling strengths to the same pile. In general, for piles with D/t ratio less than 120 and with small L/D ratio, the suction pressure to fail the pile structure is much higher than that for the soil plug failure in regular clay soil; nevertheless, this may not be applicable for piles with D/t ratio greater than 120 and with large L/D ratio. The industrial codes and standards using thin wall theories shall be adopted to design suction piles w in order to take into account various structural buckling modes. For the 3D nonlinear FEA, the post buckling analyses predict the suction pile buckling pressures and show the reduction in pressure after buckling rather than traditionally selected buckling pressure at an arbitrary displacement regardless pile geometries. The proposed approaches to generate the allowable suction pressure envelopes can lead to an economical suction pile design and provide the installation contractor with a visualize tool to ensure a safe and successful suction pile installation.
Managing Total Fluid Loss is Critical for Well Integrity Management
Authors: Savari Sharath , Whitfill Donald L. 
Published: April 2015

Abstract
Well integrity management (WIM) is predominantly viewed from a perspective in which technical, mechanical, and operational solutions are applied to help reduce the risk of uncontrolled release of wellbore fluids at unwanted times throughout the life of a well. Wellhead integrity, completion integrity, and zonal isolation are a few of the key performance indicator (KPI) parameters considered. This paper discusses WIM from a drilling fluid management perspective. Drilling fluid loss (lost circulation), if not properly addressed at the correct time, can lead to significant well control issues. Particulate lost circulation materials (LCMs) have been in use to manage lost circulation for many years. This paper discusses preventive (proactive) and remedial (reactive) operational strategies to deal with such issues.
Preventive strategies are employed to help reduce the potential for lost circulation. This strategy involves the initial consideration of lost circulation management from the wellbore planning/design phase. Improved drilling practices can be emphasized and planned by examining drilling fluid hydraulics and all other fluid engineering aspects. Finally, effective preventive engineered solutions can be considered and made available to manage losses well before they are encountered. Conversely, a prudent engineer will have remedial strategies in place if the preventive plan does not work. This strategy also includes loss contingency plans to be in place if unexpected loss events occur. Examples are discussed with respect to how previous knowledge and lessons learned can play a critical role in developing contingency plans to effectively manage losses when they occur.
In summary, this paper discusses WIM from a drilling fluids perspective and, more specifically, through managing drilling fluid losses. The preventive and remedial operational strategies presented can be critical in managing drilling fluid losses and helping prevent wellbore stability or well control situations.
Assessing Uncertainties in Wellhead System Fatigue Life Prediction
Authors: Pedro Ramón I. San , Hamilton Mark E. , Bhalla Kenneth 
Published: April 2015

Abstract
This paper examines sources of uncertainty in present analysis methodologies used for the prediction of wellhead system fatigue lives. For this study, the sources of uncertainty are classified as those parameters that affect the prediction of loads and stresses (the demand) and those parameters that affect the calculation of fatigue damage (the capacity). The combined effects of demand and capacity uncertainties are then considered to qualitatively examine the resulting uncertainty in fatigue life predictions and how uncertainty in the results can drive design and operational decisions in order to achieve the desired reliability.
Calculations, test results, and experience show that any number of factors on the demand and capacity aspects of wellhead design can result in considerable uncertainty in the prediction of fatigue performance. This makes the task of determining rational and justified safety factors, design requirements, and operational limits extremely difficult. Reduction of uncertainty is required in order to maintain or improve the reliability (i.e., reduce probability of failure) of the wellhead system while allowing design and operational flexibility without having to resort to impractical safety factors. Progress towards this goal can be achieved, in part, by: (a) developing technically sound and consistent analysis methods, (b) refining analysis inputs through complementary advanced analyses and sub- and full-scale testing of systems and components, (c) qualifying welds and components to existing design S-N curves or developing appropriate design S-N curves from material and full-scale fatigue testing in applicable environments, and (d) developing benchmarks for analytical model validation through wellhead fatigue monitoring in real time.
Brazilian Pre-Salt: An Impressive Journey from Plans and Challenges to Concrete Results
Authors: da Costa Fraga Carlos Tadeu , Capeleiro Pinto Antonio Carlos , Branco Celso Cesar Moreira , de Sant´Anna Pizarro Jorge Oscar , da Silva Paulo Cezar Augusto 
Published: April 2015

In the early 2000s the context of the pre-salt formations was conceptual geological models of possible oil bearing reservoirs underneath a thick salt layer, many technical challenges, uncertainties and risks. Past only eight years from first discovery (2006), there are nine production systems, FPSOs, in operation, reaching an average oil rate of more than 700 thousand barrels per day and a cumulative production greater than 400 million barrels of oil, through 34 production wells. To optimize recovery, the first desulfated sea water and gas injectors were started. But these impressive numbers cannot be taken from granted: although nature has revealed prolific reservoirs, much experience, talent, planning and perseverance were necessary.The first articles addressing the pre-salt fields had a focus on the technical challenges faced on first years: the heterogeneous nature of the microbial carbonate reservoir, the 2,000 m salt layer and drilling concerns associated, the variable CO2 content and compositional grading in the reservoir fluids, flow assurance issues and special demands concerning subsea engineering, well construction and processing plant. The main drivers and development strategies were also established: staged development, based on extended well tests (EWTs), multi well production pilots and definitive systems prioritizing the standardization of well projects and production systems. Now, challenges and plans are rewarding the efforts, as depicted by the concrete production numbers achieved to date.In this text, a historical perspective of the pre-salt exploration and development is presented, emphasizing the previous unknowns and uncertainties and how they were treated in order to attain the results. As we still have a lot to learn, since we are just on the beginning of the development of this extraordinary petroleum province, a look to the future and the present efforts on optimization are also commented.
Large Diameter Steel Catenary Riser Solutions for Semi-submersible Platforms in Offshore Northwest Australia
Authors: Vijayaraghavan V. , Shi X. , Lu R. , Wang T. , Haverty K. , Hagatun K. , Richards A. , Thompson H. M. , Healy N. , Jin E. 
Published: April 2015

Abstract
The offshore northwest Australian sector is dominated by large gas plays and as the sector matures there is an increasing move towards deepwater developments. Riser solutions are key concept selection drivers and often high gas throughputs have led to a drive towards large riser diameters to limit the associated subsea infrastructure. The need for high availability in LNG projects leads to a requirement for high reliability, permanently moored Offshore Facilities. A representative development scenario employs large diameter (18" to 24") import and export Steel Catenary Risers (SCRs) supported by a Semi-submersible platform in 1,400 m water depth. This is potentially the deepest development offshore Australia. It is a relatively novel solution for the region given that the riser solution in the region has been primarily limited to flexible risers.
SCR designs are governed by their fatigue performance in the touch down zone (TDZ). Feasibility of the large diameter SCRs is challenged by the Australian sea conditions dominated by southern ocean swells. Several options are considered to enhance the fatigue life of the SCRs. These include increasing the Semi draft to reduce heave motions, aligning the riser plane in a direction normal to the predominantly northeastern swell environment, using upset ends at critical locations to reduce curvature response, lazy wave configuration to decouple vessel motions from TDZ response, and weighted SCR to reduce TDZ response. These options are considered either individually or in a combination thereof. The technical feasibilities of and the challenges associated with these options are discussed. Some of the possible challenges include the manufacturability of upset ends, feasibility of top end terminations and installation of buoyancy modules. A relative cost comparison is also made between the different options.
The metocean conditions in offshore Australia are compared with US Gulf of Mexico (GoM), where SCRs have been widely used. Their implications for SCR fatigue and extreme response are explored. Findings that are critical to the riser design include riser porch vertical velocity at extreme conditions, relative contribution of surge/sway versus heave motions to fatigue damage, contribution of vortex induced motions (VIM) to fatigue damage, and effect of long term currents on riser VIV response.
Given the relative novelty of SCR applications with a Semi-submersible in offshore Australia, and the challenges associated with fatigue performance of large diameter SCRs in that harsh environment, this paper will serve as a valuable guide for future riser design and field development in the region.
Offshore Condensate Stabilization and Exportation
Authors: Vocke William , Newman Daniel , Villio Robert , Cook Charles , Taylor Denis 
Published: April 2015

Abstract
This paper discusses aspects of the process design approach used for the Delta House production facility (Mississippi Canyon 254 "A"). Specifically, the challenges associated with the disposition of NGL's (considering constraints imposed by export pipeline requirements and the desire to maximize liquids sales volumes) are addressed.
Delta House's process system was initially designed assuming a reservoir composition similar to an analogous nearby well. Based on this composition, liquids from compressor scrubbers were to be routed to production separators with lower operating pressures. This philosophy is very common for offshore facilities and caused minimal liquid recycle and a negligible increase in compression requirements.
Subsequent to this initial process design, a well sample phase behavior (PVT) analysis became available. The PVT data was believed to be representative of the majority of the production associated with Delta House. The PVT data indicated that the reservoir had an approximate stock tank gas-to-oil ratio (GOR) of 2100 and 38° API crude oil gravity. These PVT results represented a significant change from the initially assumed composition. Additionally, the reservoir fluid was very rich with condensate, particularly propanes (C3's), butanes (C4's), and pentanes (C5's).
A significant liquid recycle and a drastic increase in compression requirements were observed when the compositional basis of the reservoir was entered into the steady-state process simulator. In addition, meeting the oil pipeline Reid Vapor Pressure (RVP) specification became a significant challenge due to the rich nature of the crude. The current liquid handling philosophy no longer appeared suitable, and various options were quickly investigated and evaluated. The two most practical options were direct injection of the condensate into the gas pipeline and a full crude stabilizer. It was determined that a hybrid (a Condensate Stabilization System) of the two options was the most economical option due to the ability to recombine the stabilized condensate with the crude oil for sales.
This paper addresses the reasons, benefits, and methodology of installing a Condensate Stabilization System on the Delta House Floating Production System (FPS). It also discusses the process equipment that composes the system, the intended operating conditions, as well as the effects of seasonal variables (oil pipeline RVP specification and ambient temperatures).
A Condensate Stabilization System provides a means to optimize facility production and allows for better RVP control. This is achieved by controlling the reboiler temperature which correlates to the amount of light ends that are recycled to the bulk separation train. It also greatly reduces compression and horsepower requirements. Finally, a condensate stabilization system affords operators the ability to achieve greater margins by providing the flexibility to move liquids from the gas processing and sales system to the oil system.
Rotary Converter for Long Step-out Subsea Power Supply
Authors: Normann T. , Müller L. A. , Amundsen M. , Lien L. Krogstad , Chen A. 
Published: April 2015

New subsea power transmission technology is required in order to enable increased oil and gas recovery in deep waters and at long tieback distances. Such prospects may not be feasible to develop with today's electrical power solutions, as traditional AC power transmission methods for supplying the increased power demand to subsea compression and pumping stations are reaching their limits. HVDC is far from matured for subsea use, and may not even be necessary technology, as low frequency AC can cover the market.
Aker Solutions has developed a new patented invention, called a Rotary Converter, for low frequency (LF) AC power transmission. This unit allows an extension of the maximum power transfer of subsea cables to more than 3x the step-out and 3x the power level compared to existing technologies.
The Rotary Converter (RC) consists of a subsea motor with low input frequency (10 - 30Hz) that runs a generator on a common slowly rotating shaft in a subsea enclosure. The generator supplies high frequency power (50 - 200Hz) to subsea ESPs, pumps, compressors or other loads.
The RC is supplied from a topside VSD via a long cable, and the low frequency ensures that the capacitive power / current in the cable is significantly reduced compared to conventional transmission frequency (50/60Hz or more), allowing more power, smaller cable cross-section, lower transmission voltage and better system stability.
Furthermore, by introducing a variable coupling (e.g., hydrodynamic) between the motor and generator, the Variable Rotary Converter (VRC) can replace power electronic based subsea VSDs. Input frequency can either be conventional for short to medium step-outs, and low frequency input for longer step-outs. This allows for simple and robust torque and speed control.
Key highlights from the Rotary Converter prototype development and tests are also shown in relation with relevant power system simulations. Various applications for this technology are presented, for instance within subsea control system supply, allowing increasing the power supply capability in brownfield scenarios where all-electric control systems are increasingly used.
This technology will be a new tool to enable the oil and gas industry to develop subsea fields that would normally require an additional offshore platform or FPSO, and rather use existing infrastructure with longer cables instead.
The main benefits of this new invention can be summarized in longer step-out distance, more power, better system stability, and lower CAPEX / OPEX for subsea control systems, pumping, and/or compression.
Offshore Methane Hydrates in the Gulf of Mexico: A Study in Economic Viability
Authors: Wells Jaeger , Sansom Paul 
Published: April 2015

Abstract
Methane hydrates have long been discussed as the next cradle of energy. Considered a resource of near infinite reserve potential, methane hydrates could supplant conventional hydrocarbon-based energy for the foreseeable future. In recent years there has been considerable activity in the petroleum industry to fully understand onshore and offshore hydrate deposits and methods of extraction and production; however, a commercial scale level has not been achieved. While there have been efforts to commercialize methane hydrate development in some parts of the world, the Gulf of Mexico remains relatively unexplored in this arena. This paper evaluates the economic viability of a commercial scale offshore methane hydrate production operation in the Gulf of Mexico—by creating a sample capital cost budget.
Online Transient Simulation in Deepwater Operations: Practical Experiences
Authors: Canon Javier M. , Yau Sarah , Francisco Aurea , Angola BP , Espeland Morten , Lundsbakken Knut Even 
Published: April 2015

Abstract
This paper summarizes practical experiences after 2 years of use of an online multiphase flow transient simulator in an operating deepwater blackoil field offshore Angola. FAMS (Flow Assurance Management System) is based on state of the art thermal-hydraulic models from bottomhole to slug catcher outlet interfaced to live field instrumentation data. The application is accessed via a web-based graphical interface.
Lessons learned presented here cover technical aspects of the tool such as reliability and accuracy under different scenarios, as well as non-technical issues such as system support model and interaction between supplier and end users. Taking transient simulation models; which are traditionally restricted to project development stages, into a real-time environment can have a positive impact on Flow Assurance workflows; particularly around minimizing effort in complex thermal-hydraulic studies, planning of unforeseen operations, training of junior engineers, validation of models and identification of code capabilities and limitations.
Continuous use of FAMS over a 2-year period has helped identify its accuracy beyond field data uncertainty. Monthly steady state reports (FAMS vs. field) prepared by the Operations team have shown good agreement between predictions and measurements. Transient conditions such as production shutdowns and hot oil circulation have also been studied and showed good agreement. This has served as means of validation of flowline insulation performance. Code / model limitations have been identified particularly in the area of slug modelling. Integration of FAMS within the BP IT infrastructure and processes have proved challenging as a blueprint for this type of application is yet to be developed. In spite of challenges in this area, the tool uptime and overall health has proved acceptable. Experiences also highlight the importance of clear and rigorous processes for maintenance of the tool between tool provider, IT department and end users, as well as an appropriate allocation of resources with clear roles and responsibilities.
Currently there are not many documented cases of use of transient online systems in day to day operations. Experiences described here help demonstrate the value of online transient simulation tools in deepwater environments while highlighting challenges and areas of improvement for this technology.
Development of Extreme Wave Conditions in the Northern South China Sea: New Method Applications and Sensitivity Studies
Authors: Li Linbin , Li Luodong , Li Ping 
Published: April 2015

Abstract
This paper is based on the JIP SOCSOHS (South China Sea Oceanographic Hindcasting Study) sponsored by China Classification Society (CCS) in 2012. It focuses on the determination of the extreme wave parameters under tropical cyclone conditions, and highlights benefits and limitations of the applied new methods by comparison and sensitivity studies. Firstly, method of grid-point pooling for prediction of extreme significant wave height (Hs) is used to account for the cyclone track variability and to realize smoothing of the site-specific data for the physically homogeneous and large scale areas. Secondly, long term distributions of maximum wave height (Hmax) crest elevation (Cmax) are derived following the storm event based approach. Thirdly, short term distribution of wave period conditional on the large individual wave height in a sea state is given by multiple regressions analysis for the random wave simulation of JONSWAP spectral. And fourthly, the long term distribution of wave period (THmax) associated with the design wave height is investigated by giving a reasonable range of spreading which should be considered for offshore structure design. The approaches presented are generic and valid for other offshore areas. It should lead to improvements in development of metocean criteria for waves as well as other parameters.