bluuebunny/crossref_metadata_2025 huggingface dataset:
Fire Test Facility for Offshore Field Equipment - Success Achieved with Systems Engineering Practice
Authors: Johnson Matthew Ernst
Published: April 2019

The Advanced Technology Lab has developed a Fire Test Facility that became operational in spring 2015. This paper describes a fresh approach to the systems engineering process path taken during development to capture new capabilities and opportunities for such a system. New functions and safety features are discussed, as compared to the original system that was replaced.

Recent fire incidents on offshore rigs have increased interest in meeting rigorous standards for fire safety. As a result of a needs assessment, a replacement Fire Test Facility (FTF) was developed in order to test offshore equipment. Offshore valves and connectors on rigs must be certified to withstand sustained fire conditions per American Petroleum Institute (API) standards 6FA/B/C. The requirements include surviving fire temperatures up to 1800 F for a period of 30 minutes, while holding internal pressure and even withstanding bending loads.

Updated safety regulations at the company led to a review of the original Fire Test Facility, and it was determined that a new system was necessary to incorporate blast protection, controls automation, and situational awareness. After establishing needs and goals from our internal customer, derived requirements were generated. Using the company’s system engineering "engine", this led to a design that met customer requirements and enhanced safety. Improvements over the original system include a 6-sided bunker structure, passive ventilation, gas safety purges, remote operation to keep workers outside the hot zone, and real-time charting to assess test performance.

After integration of the facility, a verification matrix was used to assess system functionality and performance. The improved system allows for quicker test turnaround, and more refined burn tests at reduced costs compared to using external test facilities. Mock fire tests can be performed to assess "what-if" conditions prior to actual testing of equipment. Several tests were successfully performed to API standards. Results and observations throughout the systems engineering process, including systems integration and checkout of the Fire Test Facility are provided.
Power Cycle Test Bench for Accelerated Life Testing for Reliability Assessment of SiC-MOSFET in Extreme Offshore Environment
Authors: Sadat Amin Rahnama
Published: April 2019

The reliability of power semiconductor switches is important when considering their vital role in power electronic converters for downhole subsea applications. Respect to technology advancements in material sciences, power MOSFETs with wide band gap materials have been proposed such as silicon carbide (SiC) and gallium nitride (GaN) as an alternative to existing silicon (Si) based MOSFETs and IGBTs. However, reliability analysis should be performed before substituting SiC-MOSFETs in the place of existing Si-MOSFETs and IGBTs. Due to costly equipment of experimental test setup for accelerated life test, a good reliable and precise simulation-based test bench should be used to test the life test procedure before implementing actual hardware. Therefore, this paper introduces a power cycle (PC) test bench for accelerated life testing for reliability assessment of SiC-MOSFET in harsh offshore environment. The introduced test bench is a simulation-based of power switch in SimScape and LTspice and has been validated with datasheet of 1.2 kV SiC-MOSFET, CAS300M12BM2 by CREE. Preliminary hardware circuits are also shown for further experimental tests. The captured data from the Device-Under-Test (DUT) in different ambient temperatures are envisioned and provide critical information about the failure mechanisms and lifetime characteristics of power devices. The provided lifetime characteristics data of SiC-MOSFET can be used to statistically estimate the Remaining-Useful-Lifetime (RUL) of component in a real application such as downhole motor drives.
Development of Deepwater Natural Gas Hydrates
Authors: Hancock Steven , Boswell Ray , Collett Tim
Published: April 2019

Deepwater natural gas hydrate resources potentially exceed all other conventional and non-conventional hydrocarbon resources on a world-wide basis. However, before these offshore gas hydrate resources can be classified as reserves, it must be demonstrated that gas hydrates can be produced under conditions that make economic sense. The purpose of this paper is to provide an overview of the technical issues that will challenge the development of deepwater natural gas hydrates.
New Rapid Nondestructive Testing Method for Detecting and Quantifying with Material Property Changes Using Vipulanandan Impedance Corrosion Model
Authors: Vipulanandan C. , Ganapathy C. , Gebreselassie K. A. , Pan D. , Panda G. , Ganpatye A. S.
Published: April 2019

In this study, carbon steel corrosion was evaluated in salt water solutions using the newly developed non-destructive electrical method which can be easily adopted in the field for real-time monitoring and the results were compared to some standard test methods such as weight loss, corrosion rate and potential difference. The average weight loss in 10% salt solution (accelerated corrosion and also representing the hydraulic fracking fluids) in one year was 1.05% and corrosion rate was 1.54 mm/year, using the ASTM G1 method. Vipulanandan correlation model was used to represent the weight loss versus time relationship. The potential difference between the corroding steel and standard calomel electrode in 1M salt solution reduced from -0.680 V to -0.791 V in two years, a 15% total change. The use of the new nondestructive electrical method was to detect and quantify the surface and bulk corrosion in the field. Tests were performed to first verify the best electrical property that will be highly sensitive and represent the steel corrosion. The findings from this study indicated changes in the newly developed electrical corrosion index for the surface (2D representation) and the resistivity (second order tensor, 3D representation) for the bulk material using the Vipulanandan Impedance Corrosion Model. Corrosion development in 30 inches long steel specimens were studied in the 3.5% salt solution (simulating sea water) for 500 days. The changes in the specimens were monitored at regular intervals using the new two probe method and measuring the impedance-frequency relationship using alternative current up to a frequency of 300 kHz. The surface corrosion was quantified using the new electrical corrosion index parameter, which changed from point to point on the surface of the corroding steel and the change was over 200%. The change in the bulk resistivity along the length of the steel specimen was over 40,000 times (4,000,000%) in 3.5% salt solution compared to the weight loss and reduction in the potential difference. Hence the electrical resistivity for the bulk material and the new corrosion index for the surface corrosion are highly sensing parameters for detecting and quantify the corrosion in the steel.
The High Pressure Expander Process Technology for LNG Applications
Authors: Liu Yijun , Pierre Fritz , Nagavarapu Ananda Krishna
Published: April 2019

Recent focus of the LNG industry has been on developing technologies to decrease capital investment and increase operational efficiency to reduce overall cost of supply. Pursuing this target, a novel, compact, and high efficiency expander-based liquefaction technology has been developed to monetize gas assets. The technology uses a single phase methane refrigerant stream operating at distinguishingly high pressures followed by a single phase nitrogen refrigerant stream. Such a configuration dramatically improves energy efficiency (by 10 - 25 %) and train production capacity (by 100 - 150%) compared to other expander-based technologies, while maintaining process simplicity, lower equipment count, and lighter weight relative to mixed-refrigerant based liquefaction processes. Furthermore, integrating with a front-end heavy hydrocarbon removal unit, the technology also enables standardized liquefaction train design for a wide range of gas composition around a nominal train capacity. The standard design is well suited for parallel train configurations and phased development philosophy to drive design and execution efficiency. In addition to CAPEX savings, the weight and footprint savings are beneficial in locations where space is at a premium.

While the technology platform is broadly applicable for both offshore and onshore opportunities, this paper will focus on a recent offshore LNG project which showcased the technology's significant benefit in CAPEX, weight, footprint, personnel safety, insensitivity to ocean motion, refrigerant handling and many other operation advantages. It even enabled production capacity increase from 3.5 to 4.6 on the same circular hull floating facility, proving itself as a game changer to reduce cost of supply of this liquefaction project.
Implementing Innovation: Partnerships and Problem-Solving in the Defense POW/MIA Accounting Agency
Authors: Davis Kara E , Wright Jeneva P
Published: April 2019

Defense POW/MIA Accounting Agency's (DPAA) mission, the fullest possible accounting of our nation's defense personnel lost in action, drives all agency direction. This includes novel applications of multidisciplinary solutions towards maximizing agency capabilities. By building collaborations and harnessing applications for advancing technology, DPAA's Partnerships and Innovations Directorate has been a key facilitator for implementing this imperative and has proven the benefit to challenging the operational status quo. The partnership paradigm represents a game-changing model that forces stakeholders to think differently and creatively, and ultimately deviate from traditional operations.
Effective Strategies for Flow Assurance Process Design and Execution
Authors: Kondapi Phaneendra , Creek Jefferson , Chin Y. Doreen , Moe Randi
Published: April 2019

The objective of this paper is to provide the results of key offshore oil and gas developments across the globe for common strategies and significant exceptions to those strategies. Most oil and gas companies have development processes consisting of the resource and terms attractive enough for development, what is the optimal path for development; detailed engineering and design; build and commission; operate and look back.

Within this study, the projects examined reflect different producing basins, fluid type, and water and reservoir depths. Flow Assurance can be expressed as the coupling of multiphase flow and fluid phase behavior. There are only three questions to be answered for a pantheon of problems that can impede flow over the life of the development. The three questions are 1) will there be a flow assurance risk?; 2) how often will the issue require treatment?; and 3) can the risk be effectively managed by thermal, mechanical, and chemical means?

The limitations of the strategies are becoming increasingly apparent as the requirements for system performance continue to become more demanding with changing and challenging offshore environment in the current dynamic market. Subsea technologies continue to be asked to facilitate recovering oil and gas while lowering cost while improving safety and operating efficiency to meet current industry challenges. Hence, there is a greater need to understand the flow assurance strategies to reduce overall field development costs and risk, and improve operability and reliability.

Key flow assurance strategies adopted in various deepwater projects were considered for this study with an aim to summarize common strategies that arise and exceptions that could provide new strategies going forward.
Finding the Repeatability in One-Off Projects to Improve Performance
Authors: Shenoy Ramachandra Ganesh
Published: April 2019

Project teams generally believe that large oil and gas capital projects typically have unique scope and are comprised of highly customized elements. For this reason, when they hear about new technical frameworks, such as Project Production Management (PPM) (Shenoy & Zabelle, 2016), sometimes described as "applying manufacturing techniques to projects", it leads them to believe such methods only apply in scenarios with highly repeatable and predictable conditions in tasks and processes. Consequently, many experienced project professionals find it difficult to see how to apply PPM. They mistakenly believe that PPM implies a "manufacturing approach" and reject it as appropriate for the work activities in capital projects.

We show that large capital projects in oil and gas have a lot of inherent repeatability, using a well-known analysis of processes and products called the Product-Process Matrix (Hayes & Wheelwright, Link Manufacturing Process and Product Lifecycles, 1979) (Hayes & Wheelwright, The Dynamics of Process-Product Lifecycles, 1979). We use this observation to show Project Production Management applies to the execution and delivery of all projects, large or small, customized or standardized, and will improve upon prior conventional project management practices.

Project Production Management is based on the operations research foundation of production systems. We elaborate upon this foundation underpinning the PPM framework, showing how it allows one to take advantage of repeatability occurring in project work activities in different forms – knowledge, process and products. We start by identifying the assumptions of repeatable knowledge implicit in the disciplines used in conventional project management. We review the prior literature and taxonomy of a production system. All manufacturing systems are production systems. However, not all production systems are manufacturing systems. Manufacturing systems are but one type of production system. We explain that the belief that PPM is a simple application of line flow – also known as high volume manufacturing – is an overly simplistic characterization of PPM. A deeper analysis of the work activities of projects shows different types of production systems embedded within a typical project. Describing the work activities encountered in a project as a set of inter-connected production systems makes them amenable to the modeling and analysis tools of PPM, such as Little's Law and Kingman's Formula, which can be used to predict the limits of project execution and where best to manage variability by the strategic allocation of buffers such as capacity, inventory and time. We illustrate the concepts by identifying examples of repeatability present in an actual oil and gas capital project, an offshore rig.
Why Not Boosting? Uncover the True Value of Your Subsea Asset
Authors: Stenhaug Morten , Dong Hongkun , Hjelmeland Mads
Published: April 2019

The first subsea multiphase boosting system was installed in 1994 and it is today a proven technology with a global track record. In addition to bringing increased production and recovery, multiphase boosting may also reduce flow assurance issues, reduce project CAPEX and OPEX, improve operability and safety as well as reduce the greenhouse gas emissions when compared to gas lift, the default lifting solution.

A review of the evaluation process and drivers during subsea artificial lift evaluations over the last three decades indicates that in general only a few of the actual upsides of subsea multiphase boosting have been considered, suggesting that there is a need for a more complete overview of the advantages and an approach to uncovering and quantifying the actual value.

This paper discusses the different aspects of subsea multiphase boosting through a comprehensive list of tangible benefits that may support the field development decision process towards identifying the potentially significant and hidden value of subsea multiphase boosting. Referencing experience from more than 30 installations it also provides a historical summary of the various aspects of subsea boosting and which drivers were and were not considered during the decision making process.
The Experiences and Lessons Learned from the Development of High Temperature and High Pressure Buried Hillss Reservoir
Authors: Luo Xianbo , Zhu Zhiqiang , Yue Baolin , Shi Hongfu , He Yifan
Published: April 2019

The Archean buried hillss reservoir of Z Oilfield is the first one developed in the Bohai Bay Basin in recent years. In order to develop the offshore metamorphic buried hillss reservoir with limited wells, several solutions were present in the process of ODP (Overall Development Plan) implementation.

The characterization and quantitative description of fracture: The seismic forward modeling was used to identify the relationship between seismic attributes and fracture. The results showed that pre-stack shear wave impedance inversion could predict favorable reservoir development and the different frequency properties could detect the fracture. Furthermore, the rock stress field simulation based on rock physical properties was implemented to study the direction of fracture, the detailed characterization of fractured system, the quantitative prediction of high quality reservoir space distribution including porosity of fracture. This paper studied the development mechanism of buried hills reservoir with double system-fracture and matrix by comprehensive physical simulation, numerical simulation and other data. A new injection-production pattern named PT-IB (produced wells on the top of hills and injected wells in the bottom of hills) was proposed to maximize recovery factor. A new method was adopted to avoid the injected water channeling along the fractures and to enlarge the sweep efficiency by periodic change flow field. This paper also put forward a plan about early warning and judging the water channeling based on improved water oil ratio and water oil ratio derivative curve.
Innovative Oil Offloading System for Deep Water
Authors: Araújo Jairo Bastos , Fernandes Antonio Carlos , Jr. Joel Sena Sales , Thurler Ana Clara , Vilela Alexandre Mattar
Published: April 2019

Offshore oil production with the employment of FPSOs (Floating, Production, Storage and Offloading) unit faces the challenge of increasing well volumes, processing and storage capacity and ultimately oil offloading and transportation. Following the natural activity development in some oil fields, the number of spread-moored FPSOs and the employment of Dynamic Positioning Shuttle Tankers increased, however represent altogether a bottleneck for the production capacity and considerable transportation cost increment. The need to implement alternatives for the use of larger and conventional tankers is evident, and several attempts and use of technology are being tested and proposed. The work presents preliminary numerical and cost analysis of an innovative Oil Loading Terminal (OLT) for deep water.

Based on field data, metocean studies and extensive practical experience, the OLT should allow direct offloading from the FPSOs onto conventional shuttle tankers including VLCCs. The OLT concept allows the transfer of oil from an FPSO to a conventional tanker moored in CALM Buoy through submerged oil offloading lines (OOLs) supported by a tethered submerged buoy. The conventional tanker will receive the oil through a floating hose string.

The cornerstone of this OLT concept is the subsurface buoy application to support the OLLs and consequently de-coupling the FPSO and CALM Buoy motions simultaneously. As a result, the OOLs loads and fatigue efforts under the CALM Buoy also decrease. The paper evaluates an OLT specific conception for the Brazilian offshore pre-salt area and results related to the numerical analysis carried out are presented considering one submerged buoy connected to a FPSO and CALM Buoy via flexible offloading lines respectively. The results appoint to a technically feasible solution that can be complementarily laboratory and field tested. Further, the solution cost impact has been assessed and initial figures demonstrate that the final testing, construction and installation of one system will need investment that cost a fraction of tanker lifting costs currently requiring Ship-to-Ship oil transfers.

The economies assessed with the use of this innovative solution include total avoidance of Ship-to-Ship costs; cuts transportation cost per ton in up to 50% (fifty percent), eliminates offloading bottlenecks allowing better use of FPSO storage and plant processing capacity, and ultimately decreases the number of tanker offloading operations with considerable benefit to operational safety by reducing risk exposure.
Experimental and Pilot Tests of Deep Profile Control by Injecting Small Slug-Size Nano-Microsphere in Offshore Oil Fields
Authors: Su Yanchun , Li Yanlai , Wang Liliei , He Yifan
Published: April 2019

In order to test the effectiveness and efficiency of nano-microspheres which can be used to effectively reduce water cut with a small slug size, a series of experimental tests have been conducted to evaluate the performance of nano-microspheres and factors affecting the performance. Those tests include hydration swelling characteristics, blocking and migration characteristics, salt resistance, shear resistance and so on. Based on the experimental study, detailed pilot test design were conducted by considering the different reservoir pore structures and microsphere sizes used for oil displacement, so that the slug size is minimized while the net revenue is maximized. Since 2009, deep profile control technology by injecting small slug-size nano-microsphere has been developed in offshore oilfields in Bohai Sea. The main mechanism of nano-microsphere is different from the traditional approaches which increase the water phase viscosity to improve mobility ratio. In nano-microsphere deep profile control technology, nano/micron level microspheres were dispersed in the water phase. Along with the water injected into formation, microspheres swell under the formation condition, plug the water channels, reduce the permeability of high permeable zone, dynamically change the water flow paths, thus increase the water sweeping efficiency. Since 2009, a total of 17 well patterns have implemented in QHD, BZ28, BZ29 oilfields in Bohai Sea. In all those tests, small slug sizes in the range from 0.01 to 0.02 PV were used. Water cut is reduced from 80% to 70% and cumulative oil production was increased by 13.1×106m3. The economic evaluation suggests that for every one dollar investment on this technology, 3.1 dollar can be made even when the oil price is $30 per barrel. So the project has a good technical and economic outcome even in extreme low oil prices.
Revolutionizing Subsea Field Development Planning Through System Integration and Advanced Diagnostics
Authors: Chidiac Cedric , Holyfield Simon , Roberts Ian , Sauve Robert , Simpson Nicholas , Huynh Uyen , Torres Jose
Published: April 2019

Field development planning (FDP) is a multidisciplinary process that is complex, time consuming, and inefficient. Existing workflows are domain centric and involve many discrete software programs, making the process linear, limiting optimization, and often preventing cross-domain collaboration.

Although a few software tools exist for parts of the field layout design, no existing software integrates the equipment selection, systems knowledge, field layout, economics, and software simulations spanning the entire planning process from feasibility studies to detail design and optimization.

This paper demonstrates how a novel FDP software package revolutionizes integrated concept development within the industry, supporting the process from reservoir engineering through to definition of the subsea system.

In early FDP stages, including feasibility and concept selection, operators plan for the development of a field that will produce for 20 years or more, making critical decisions with very limited reservoir information and a high level of uncertainty. Because these early stages are short, operators rarely have the time or resources necessary to evaluate all possible development scenarios, and decisions are delivered with less conviction than is desirable. Hence, operators are in constant search for tools and processes that enable evaluation of more options to help them make better-quality decisions in these early stages, where reducing uncertainty and making decisions are critical to achieving first oil faster.

The paper describes an innovative FDP methodology that utilizes the industry's first cloud-based collaborative subsea FDP software environment and provides efficiency and optimization by combining full-field economic calculations with reservoir engineering, production assurance, systems engineering, subsea technology selection and installation knowledge spanning the entire planning process in one visually rich environment.

The paper demonstrates how the solution provides the ability to evaluate technical feasibility and economic viability of hundreds of development scenarios during early FDP stages more accurately and in less time compared with traditional methods. The impacts on the industry are numerous and include efficiency gains, risk reduction, and significant system cost savings, thereby improving cash flow and reducing payback periods.
A Family of Practical Foundation Models for Dynamic Analyses of Offshore Wind Turbines
Authors: Page Ana María , Løkke Arnkjell , Skau Kristoffer Skjolden , De Vaal Jacobus Bernardus
Published: April 2019

The concept of macro-element modelling – which was first introduced almost 30 years ago – has proven to be a convenient and accurate technique for modelling offshore foundations, but historically these models have mainly been used for academic purposes. Recent developments in foundation modelling now allow for application of such models in engineering practise and design. One such example is the family of new macro-element models that have been developed in the research project REDWIN to represent the foundation behaviour in dynamic analyses of Offshore Wind Turbines (OWTs). These models exhibit characteristic foundation behaviour such as nonlinearity, coupling of the load from different load components and hysteretic load dependent damping.

This paper presents two of the REDWIN models, one applicable for monopile foundations and one for skirted suction caisson foundations. Use of the models are demonstrated through two practical problems that reflect typical design analyses of OWTs: the first example shows a fatigue damage assessment for a monopile, and the second considers an extreme load event for a suction bucket jacket. The structural response is computed using the REDWIN foundation models and compared with the response based on distributed API p-y springs for the monopile and clamped legs at seabed for the jacket. Special emphasis is devoted to how the model input is obtained to guide readers on practical use of the models.
Practical Method for Simulating Flotation for Produced Water System Design
Authors: Straw Matt , Fielding David , Kay Edward , Lo Simon , Eppinger Thomas
Published: April 2019

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.
Simulation Modeling of Offshore Energy Systems & Processes - A Primer
Authors: Dronzek Rainer
Published: April 2019

An introduction to the history, concepts, use cases and technology of dynamic computer-based simulation modeling, including case studies and model demonstrations. The focus of this paper is how simulation models are developed to analyze and predict the performance of a wide range of systems and processes in the energy sector.
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

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

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

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

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

Riser-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

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

Coupling 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.