bluuebunny/crossref_metadata_2025 huggingface dataset:
Emerging Inspection Technologies – Enabling Remote Surveys/Inspections
Authors: Wen Feng , Pray Julie , McSweeney Kevin , Gu Hai
Published: April 2019

Emerging inspection technologies, tools and platforms such as unmanned aerial vehicles (UAVs), remotely operated vehicles (ROVs), robotic crawlers, and wearable/handheld devices are creating actionable data to help enable more informed decision making and improve process efficiency during survey and inspection related activities. This paper will discuss ABS’ initiatives to further understand and help define the use of and the integration of these tools and technologies to support the evolution of the maritime industry's transition to digitalization.

ABS, in conjunction with technology equipment manufacturers and service providers, has been conducting feasibility trials to evaluate the pragmatic application and implementation of these technologies to support Class surveys. These trials have focused on areas such as the detection of coating breakdowns using high-definition optics to aid in close-up visual inspections (CVI) and leveraging mobile platforms (wearable and handheld devices) in conjunction with a collaborative software platform to execute survey activities virtually in real-time (connected) or near real-time (disconnected), capturing data as required by Class Rules.

In support of these trials, ABS is actively involved in a joint development project (JDP) with academia focusing on the realization of image recognition (artificial Intelligence [AI]) into the survey decision-making process. As part of this JDP, an AI software was developed incorporating thousands of damaged structural coating images. These images were used for the training, testing and evaluation of the software's image recognition capabilities.

This paper discusses the results of the feasibility trials and the next steps in the digital evolution for Classification Society activities. Potential applications include but are not limited to: condition-based/remote surveys, evaluation of maintenance programs, development of 3D models with 3D scanning/image data capture, documentation auditing, and corrosion mapping of steel plates.
Digital Twin of Subsea Pipelines: Conceptual Design Integrating IoT, Machine Learning and Data Analytics
Authors: Bhowmik Subrata
Published: April 2019

Digital Twin is a new paradigm combining multiphysics modelling together with data-driven analytics. In recent years, it draws considerable interest from the oil and gas field operators due to lower oil prices to reduce the downtime due to planned or unplanned preventive maintenance in production field which cost several million in the operational cost (OPEX). The digital twin is an integrated system with low-cost IoT sensors to gather system data, advanced data analytics to draw meaningful insights and predictive maintenance strategy based on the machine learning algorithm to reduce preventive maintenance cost. Overall the digital twin act as a digital replica of the field asset which is monitored and maintained based on actual sensor data from the physical field using machine learning.

This paper will demonstrate the conceptual design of a digital twin of subsea pipeline system integrating the computational model, field sensor data analytics and predictive maintenance based on the machine learning algorithm. The computational model is first developed in the finite element (FE) model and calibrated by the field sensor data installed on the physical system.

The computational model will be used to predict any change of pipe behaviour due to sudden changes in loading due to high pressure, slugging or leak etc. The proposed digital twin model will assist the oil and gas field operators in minimizing the OPEX with predictive maintenance schedule when it's needed to avoid failure in the pipeline system.
Advanced Mud Logging: Key to Safe and Efficient Well Delivery
Authors: Blue Duncan , Blakey Thuy , Rowe Mathew
Published: April 2019

The high costs and high potential risks associated with drilling deepwater wells have prompted the development of an advanced computerized mud logging system. This paper highlights select technologies within the system and its application to three core areas of operation—circulating, making connections, and tripping—to provide early identification of fluid influxes and losses, thus helping ensure safe and efficient well delivery.

The advanced mud logging system includes a kick-detection system, flowback monitoring, trip monitoring software, and mud accounting software based on a new methodology. The kick-detection system uses advanced flowmeters to enable stricter control of the drilling process; fluid influxes or losses are detected by integrating the variance for predicted and measured flow and alarming, with as little as a barrel gained or lost. Flowback monitoring uses sophisticated algorithms in conjunction with the same high-accuracy flowmeters to monitor influxes while making connections. These algorithms drive a complex alarm system tuned to trigger on minimal flow variance, pit volumes, and the rate of modification of each compared to a historical baseline. Additionally, trip-monitoring software automates the tracking of pipe displacements in real time to warn of a well control event, instead of relying on spreadsheets or handwritten calculations. Mud accounting software tracks drilling fluid balance across the entire pit system for redundant influx and loss detection and accounts for volume changes based on circulating rates.

Application of the advanced mud logging system in the deepwater Gulf of Mexico (GOM) provided earlier detection of well control events—up to 10 minutes earlier than conventional well monitoring techniques. Flowback monitoring demonstrated the ability to identify minimal flow when making connections, which would be difficult to detect by visual inspection. The ability to trend flowback profiles consistently has allowed operators to reduce the pump's off time while making connections in less than 5 minutes, without jeopardizing the ability to confirm a static well.

Additionally, the advanced system enables drilling operations to proceed without increasing mud weight and exacerbating wellbore damage during a ballooning event.

This paper presents a case study in which the history of well control events documented in the literature was reviewed to help identify areas of improvement.
A Critical Appraisal of the Benefits of and Obstacles to Gaining Quality Data with Offshore Seismic CPT and P-S Logging.
Authors: Masters Toby Alexander , Juszkiewicz Patryk , Mandolini Alessandro , Christian Harold
Published: April 2019

Soil stiffness is a key criterion in the design of OWT foundations. The necessity for the development of accurate in-situ small strain moduli profiles has led to an increased interest in using Seismic CPT (SCPT) and P-S Suspension logging. This paper describes both methods, weighs up the relative benefits (and limitations) and identifies the obstacles experienced in the data processing in order to gain reliable results. The accuracy of the techniques is evaluated through the site investigations for wind farm developments and compared against shear moduli derived from advanced laboratory tests on the soil element. The relative performance is made more complicated by the location of the investigation, often including placing additional equipment on the seafloor (in the case of SCPT) and having to work with heave compensated systems. P-S waves were found to be affected by the borehole conditions in terms of borehole diameter, irregularity of its walls (rugosity and/roughness), cavitation issues, fractures and ambient noises (especially at shallow depth), as well as borehole stability. The analysis of the results confirmed that both in-situ testing methods have promising potential in the evaluation of soil stiffness with higher characteristic values being derived than those by laboratory testing, leading to potential foundation cost reduction. There are distinct benefits achievable by performing seismic tests in-situ.
Implementation of XFEM for Fitness-For-Service Assessments in Life Extension and Damaged Structure Applications
Authors: Liu Meng-Lung , John Smarty Mathew , Lin Jessie , Massingill Amanda
Published: April 2019

Fitness-for-service (FFS) assessments are critical to the integrity management of offshore and subsea assets. Decisions regarding continued service life or the need for corrective action for damaged structures pivot on accurate FFS assessment results. While FFS assessments using failure assessment diagrams (FAD) and finite element method (FEM) have been successfully implemented on simple and regular geometries, they are not suitable for structures with complex geometries, transition of failure modes, presence of residual stress, and nonlinear fracture toughness. Extended finite element method (XFEM), a fracture mechanics-based approach enriched by extra functions around a crack, is capable of considering the above mentioned scenarios and evaluating the crack behavior. This paper demonstrates the performance of XFEM and validates the results obtained from XFEM.

First, XFEM is implemented in assessing a stationary crack on ASTM Compact Test (CT) specimen to calculate the stress intensity factor (SIF) which the obtained results deviate from the analytical solution by less than 6% for various crack length cases. Following that, a cracked plate case treated with cold expansion technique is investigated. Its remaining fatigue life is obtained by simulating fatigue crack growth, under two sets of residual stresses generated by different mandrel diameters. The results are then compared to the crack arrest hole (CAH) approach.

Through these case studies, XFEM shows adequacy for FFS applications. XFEM facilitates the modeling of the crack surface, and eliminates the need to remesh for crack growth analysis. Arbitrary structure geometries and loading combinations can be directly used in XFEM since the stress and strain responses are calculated in a conventional FEM framework. This means that the presence of local corrosion and dents, as well as transition of failure modes can be accounted for. The residual stress effect can be accurately calculated and considered for SIF calculation. Although XFEM appears to be a good solution for FFS application, adequate caution should be given to the mesh size selection and mesh orientation because they may cause slight or noticeable fluctuation of results. Therefore, a mesh sensitivity study is recommended.
Wellbore Schematics to Structured Data Using Artificial Intelligence Tools
Authors: Kemajou Vanessa Ndonhong , Bao Anqi , Germain Olivier
Published: April 2019

Wellbore schematics are essential to well planning and operations because they detail well design, completions, and sometimes the production mechanism. There are multiple formats and types of wellbore schematics; however, they generally consist of a well diagram accompanied by tables of annotations listing components and equipment details such as depths and diameters. Paper-based wellbore schematic reports are often distributed as the primary account of technical information concerning old wells after being acquired by oil and gas operators. Any intervention or further operation on those wells would require a thorough and manual interpretation of those reports, which can be lengthy and prone to errors. Therefore, to automatically convert the diagram and annotations into a readable database, a practical technique or tool has to be developed.

Artificial intelligence (AI)-powered image analysis addresses similar problems for other engineering disciplines and industries, and with the latest advances for software and computer hardware capabilities, it is possible to design specialized solutions for the oil and gas industry. Therefore, a methodology was defined and implemented to import the available machine learning technology for automating the interpretation and analysis of wellbore schematics. With this novel tool, scanning the paper-based wellbore schematic results in digital and easily shareable structured data that can be used to regenerate a digital wellbore schematic. This method analyzes the diagram and the annotations on the wellbore schematic file and then combines the analysis results by matching the diagram with the surrounding annotations and engineering constraints.

The methodology was tested on a set of wellbore schematic files, and digital schematics were regenerated. Fundamental components and equipment were detected that matched the original schematics in terms of depths and diameters. The designed tool saves considerable time and effort while providing accuracy and repeatability. These results highlight some of the benefits of applying multidisciplinary ideas for data management to the industry.

The object detection technique in image analytics is new to the oil and gas industry for identifying components in well schematics. Further, this project is comprehensive because it identifies the diagram and related annotations. Challenges and breakthroughs experienced in this research will be addressed.
Significance and Potential Benefits of Bulk Material Standardization for Offshore Projects
Authors: Singh Kanika , Jeon Hyun Buki , Ellingsen Hans Petter , Do Hyunsun , Son Jin Seong , Min Gi Eob , Jeong Byoung Min , Kim Dong Woo , Kang Do Wook , Shin Hyun Chang
Published: April 2019

Oil and gas companies are focusing to solve the challenges of high-cost, high-risk and adverse market conditions in offshore production. These ongoing challenges and uncertainties with the fluctuating oil prices and increasing regulatory and safety requirements, have prompted oil and gas companies to explore ways to improve efficiency and productivity through standardization. Many of the offshore projects were analyzed before the launch of Unified Bulk Joint Industry Project (UBJIP) which has evolved in various phases. The main objective of the paper is to discuss the standard specification of Electrical and Instrument(E&I) components, Piping and Structure material. It is essential to state a defined significant purpose and benefit of the standardization work and assure that the actual efforts contribute to the overall savings.

This paper focuses on the common specification in compliance with a cross-industry specification and includes details of the planning and execution of on-going standardization program. When standardizing, there are several considerations. The selection of bulk material is based on high-volume value and quality aspects which have significant impact when prioritizing among the components. The methodology adopted to develop the standard specifications of bulk items (for Electrical & Instrumentation, Piping and Structure) is identified by performing the gap analysis among local regulations, industry standards and major offshore project specifications. The developed standard specifications are based on evaluation and verification with prototype risk and business case studies.

The findings of this paper cover the new standardization specification for cable glands, cable terminations and penetrations, pipe supports, flange management systems and outfitting. In some cases, the lack of international standards and codes in some areas was identified where the gaps were filled with the new UBJIP standard specifications. The significance and benefit criteria for standardization focuses on cost, weight, construction efficiency, compatibility, safety requirements and operational maintenance.

The novel aspects of this paper address the challenges posed in design, materials, and procedures to meet a cross-industry specification, i.e. UBJIP IOSS (Integrated Offshore Standard Specification, soon to be incorporated into an ISO/IEC specification). The future steps and roadmap towards global standards are covered in this paper.
Utilizing 3D Optical and Acoustic Scanning Systems to Investigate Impacts from the Oil Spill on Historic Shipwrecks
Authors: Damour Melanie , Church Robert , Warren Daniel , Horrell Christopher
Published: April 2019

The U.S. Bureau of Ocean Energy Management (BOEM) and Bureau of Safety and Environmental Enforcement (BSEE) are required to consider the effects of their permitted actions on cultural resources, per the National Historic Preservation Act (1966). After the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, BOEM, BSEE, and study partners implemented a multidisciplinary approach to assess micro- to macro-scale impacts from the spill on a select number of previously investigated deepwater shipwrecks. The Gulf of Mexico Shipwreck Corrosion, Hydrocarbon Exposure, Microbiology, and Archaeology (GOM-SCHEMA) Project collected microbiological, geochemical, and archaeological data at wooden- and metal-hulled shipwrecks within and outside of the spill-impacted area for a comparative analysis. Archaeologists documented the selected shipwrecks’ post-spill state of preservation using 3D optical and acoustic scanning systems for comparison with existing geophysical and visual data collected prior to the spill.

Marine archaeologists are using 3D scanning systems as new tools for recording and interpreting shipwreck sites and analyzing site formation processes in the marine environment. The GOM-SCHEMA Project combined 3D laser data from an Autonomous Underwater Vehicle (AUV) with 3D sonar data collected by a Remotely Operated Vehicle (ROV) as a first step toward monitoring efforts that will inform BOEM and BSEE of the spill’s long-term impacts on deepwater shipwreck preservation. Employing microbial ecological analyses and laboratory-based corrosion experiments that identified micro-scale impacts, scientists gained a better understanding of how the spill affected the natural processes of metal corrosion and wood degradation. 3D imaging creates a permanent digital record that allows scientists to study minute details and also serves as an important outreach tool by allowing the public to virtually explore archaeological resources. By comparing 3D scans collected repeatedly at the same sites over time, especially the sub-centimeter-accurate 3D laser data, archaeologists can quantitatively analyze changes occurring on these sites as a result of enhanced corrosion or degradation. Collectively, these datasets can inform archaeologists and submerged cultural resource managers about site stability, formation processes such as sedimentation and scouring, and the long-term impacts of a major oil spill on submerged cultural resources.
Analyzing Swellable Packer Model Under Miscible Gas Differential Pressure Utilizing Computerized Tomography Scanning
Authors: Pounds Rob , Glaesman Chad
Published: April 2019

The purpose of this project was to confirm the occurrence of and to characterize hydrocarbon gas diffusion through a swollen reduced-scale packer of oil swellable material. The extent and origin of extrusion at the ends of the scaled packer is a key measurement. A quantitative and qualitative analysis was performed to determine if the miscible gas mixture damaged the structure or compromised the capability of the elastomer / swellable packer to hold pressure.

Two packers were swollen (separate fixtures) in diesel under conditions similar to downhole pressure and temperature. The test fixtures were limited to an internal pressure of 2000 psi. A 1900 psi differential pressure was applied across the two test samples using the swell fluid. A temperature of 72ºC was maintained for the test. A miscible hydrocarbon gas was then introduced (1900 psi) to one of the test samples to completely displace diesel from the high-pressure side of the test fixture. Pressure and temperature were maintained for approximately 35 days during which regular computed tomography scans were conducted to detect any changes in the density of the swellable rubber element.
Solving the Operational Challenges of Sulfate Removal Units Using High-Flux, Fouling-Resistant Nanofiltration Membranes
Authors: Krebs Thomas , Ganguli Rahul , Lage Gustavo , Verbeek Paul , Mehrotra Vivek , Florido Priscilla , Akdim Mohamed Reda
Published: April 2019

Desulfation of seawater before injection is required to control reservoir souring and scale formation. For this task, operators use nanofiltration (NF) membranes in sulfate removal units (SRUs). The tendency of the membranes to foul is a key operational challenge. To overcome fouling, frequent chemical cleaning is required. An additional constraint for SRUs is that the amount of treated water cannot be increased easily as a higher water output results in an even faster fouling of membranes.

In this paper, we describe a method to enhance permeate flux and fouling resistance of desulfation membranes. The enhancements are achieved by modifying the active layer of commercially available NF membranes using a permanent coating that increases hydrophilicity while retaining the high surface charge characteristic of NF membranes.

We report the results of a six-month field trial with the coated membranes. The test was executed at the Seawater Desalination Test Facility in Port Hueneme, California using 2.5" dia. membrane modules. The test skid contained two different parallel flow lines with a stack of six coated 2.5" dia. membranes in series, and an uncoated 2.5" membrane for reference.

The results show a 25% higher permeate flux for the coated membranes compared to the uncoated membrane at the same transmembrane pressure. Sulfate rejection was unchanged for both coated and uncoated membranes during the entire duration of the test. The coated membrane also showed a lower fouling rate than the uncoated membrane. The time between cleaning events increased by ∼ 38 % for the coated membranes as compared to the uncoated membrane, and the coated membrane processed ∼ 63 % more permeate before cleaning was required. Preliminary results also indicate an enhanced chlorine tolerance of the coated membranes of at least 3000 ppm-h under continuous chlorination at ∼ 1 ppm.

The impact of the coating on the economics of SRU operations will be discussed in the paper. The results presented in this paper demonstrate that performance and operability of SRUs can be significantly enhanced by a newly-developed coating, and that a significant reduction in the lifecycle cost of SRUs can be achieved.
Comparison of Coupled and Decoupled Seismic Analysis of TLP Piles
Authors: Suroor Hadi , Arablouei Amir
Published: April 2019

Tension-leg-platforms (TLPs) are increasingly being used in offshore regions of high seismicity. The TLP foundation typically consists of very long driven piles supporting the TLP tendon loads. These piles experience significant uplift loads generated by the inherent system buoyancy. API RP 2T is considered the industry standard for TLP design which provides guidance on foundation design; however; available guidance on seismic design of TLP foundations is limited. The focus of this paper is to present and compare two types of seismic design methods for TLP piles and discuss associated outcomes, which should provide greater insight into the complexities involved in seismic design analysis.

The seismic analysis of TLP piles can be performed in two ways; coupled and decoupled analysis. In a conventional decoupled analysis, as practiced in the industry, the foundation pile is analyzed independent of the TLP structure considering various design loading conditions, including seismic loads. In the coupled analysis, the entire system including TLP structure, tendons, and piles are modeled and analyzed as one integrated system. This is done to investigate both system and component responses due to the impact of seismic ground motions. In the coupled approach, the system can be analyzed by the response spectra method for an extreme level earthquake (ELE) and the dynamic non-linear analysis for an abnormal level earthquake (ALE). The effects of seismic kinematics and inertia, soil degradation due to cyclic loading, soil damping, etc. are considered in both types of analyses.

Two case studies are presented where these methods have been applied for two TLP projects located in seismically active regions. The outcome of the study is to present a comparison between the conventional decoupled approach and the proposed coupled seismic analyses of TLP piles. This comprehensive seismic study aims to provide detailed insight into the seismic design methods of a TLP foundation to supplement the design guidance presented in API RP 2T. Although complex and time consuming, the proposed coupled approach provides greater insight into the system response.
Lean Duplex Grating Solutions to Mitigate Corrosion Problems and Weight Reduction Challenges in Offshore Platforms
Authors: Pathirana Sanj C , Claesson Peder , Kirchhartz Thomas
Published: April 2019

With the growing demand in cost reduction on maintenance activities as well as weight reduction solutions, it is necessary to invest in new technology and design solutions in the offshore industry.

The use of lean duplex materials has been on-going for over a decade but the application in offshore industry, specifically in new platform design and modification activities, has been quite recent. This paper gives an outlook on lean duplex material and the results of a pilot project developing a grating design which was supported by Oil & Gas Company in Norway with the aim of using lean duplex gratings in the next available modification project.

The most commonly used solution in the Norwegian offshore industry is HDG gratings. These gratings are available as ready-use cut-to-length solutions to cover the required surface area from various manufacturers.

With the mind-set of developing alternative solutions to existing grating options, selection of a superior material type with favourable characteristics such as higher corrosion resistance, mechanical properties and weldability are some of the key focus points.

At the development stage two different Lean duplex grating prototypes have been designed. The primary goal of the design was to meet all the current offshore requirements while reducing the weight on the final product. Having the option of lean duplex as the material choice for gratings provides key advantages in weight reductions and superior corrosion resistance in saline atmosphere resulting in longer lifecycle times.

The design focus on lean duplex gratings has been presently limited to the platforms, staircases and walkways, but there are a more possibilities for optimization of the design when balancing the cost / benefits of the following factors: ▪Design/Weight▪Lifetime/ Maintenance – Low Carbon Footprint▪Cost

This product development can be viewed as an incremental innovation showing the potential where a small piloting scope can have larger implications if applied in larger scale modification projects.
Integrity Management of Mooring Systems
Authors: Hageman Remco , Aalberts Pieter , Leeuwenburgh Richard , Grasso Nicola
Published: April 2019

Mooring systems remain an important component of an overall field development. There are numerous sources in literature describing challenges with mooring systems as well as potential solutions.

The goal of this paper is to present a number of new technologies which can be applied jointly in an integrated framework to monitor integrity of subsea mooring components. The paper will cover (1) direct tension measurements using Vibrating Wire Gauges, (2) warning systems based on anomaly detections from GPS measurements and (3) mooring line force estimation method and fatigue using time-domain simulation methods.

Vibrating Wire Gauges are a potential alternative to the use of in-line load cells or inclinometers for measuring mooring line tensions. These sensors have a proven track record in the Geotechnical Industry. A sensor dedicated for the offshore industry has been developed. The main benefit of this type of sensor is the ease of retrofitting in an offshore environment. Long-term stability tests and dynamic tests were executed and will be presented. Procedures for installation and maintenance were developed.

GPS measurements have widely been used in the industry to identify mooring failures. Post-processing methods of these measurements range from application of watch circles to Artificial Neural Networks. However, there remain important challenges with performance of these warning systems under the influence of environmental loads. The authors will show a basic concept which can overcome these limitations.

High accuracy floater position and motion measurements can be used in combination with a numerical model to determine mooring line forces in the field. This approach combines the numerical models used in the design with onboard integrity and maintenance procedures. The technical and organisational challenges of such approach are discussed. An onboard system able to capture system drift is used to update the numerical model and correct for deterioration of the mooring system over time. In-service measurements have been used to demonstrate and validate the concept. The methodology has been implemented and installed on an offshore asset which will become active in Q1 2019.

A number of industry solutions for mooring line integrity methods have been compared. All presented solutions have a role in the total mooring subsea integrity management program. Integration of these components together or supplemented with numerical analysis can be used to develop an overall mooring subsea integrity management plan and philosophy.
Erosion and Structural Integrity of Mud Pulse Telemetry Tools: Numerical Simulation and Field Studies
Authors: Mohammad Elyyan , Yuan Peng , Muhammad Sami , Zhang Hao , Huang Xu
Published: April 2019

Deepwater exploration and production presents some of the industry's most complex challenges, requiring huge capital investment and long-term commitment. Subsea fields face exceptional challenges during drilling, cementing, and operations. Any downtime means project delay and lost production. Consequently, it is important to have real-time data from high-fidelity measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools during drilling operations.

Mud pulse telemetry is a widely used method to transmit MWD and LWD data to the surface. Availability of this real-time data is important for the economic success of the drilling operation. Consequently, it is important to maintain operational telemetry systems that provide fast and reliable data rates for downhole drilling. However, telemetry system failure due to sand erosion can be costly and cause downtime and maintenance costs to the operators. Hence, there is a constant need for accurate prediction of the location and erosion rate of these downhole systems.

In this study, we build on our earlier work, where we presented a comprehensive investigation on erosion of mud pulse telemetry tools consisting of numerical simulations and field data. In the current work, we take the numerical analysis further: we predict the location of the high erosion rates and model equipment topological changes due to sand erosion and its impact to fluid flow. The importance of this step is to capture the effect of changing geometry on the erosion rate, enabling us to estimate the reliability of the tool accurately. In addition, we investigate the structural integrity of the tool and the effect that sand erosion has on it. Structural integrity analysis of the eroded tool geometry is performed using finite element analysis (FEA). For model validation, simulation results will be compared with erosion patterns from field tests.
Assessment of Wave Energy Resources and Factors Affecting Conversion
Authors: Jones Craig , Chang Grace , Dallman Ann , Roberts Jesse , Raghukumar Kaustubha , McWilliams Sam
Published: April 2019

The wave energy resource for U.S. coastal regions has been estimated at approximately 1,200 TWh/yr (EPRI 2011). The magnitude is comparable to the natural gas and coal energy generation. Although the wave energy industry is relatively new from a commercial perspective, wave energy conversion (WEC) technology is developing at an increasing pace. Ramping up to commercial scale deployment of WEC arrays requires demonstration of performance that is economically competitive with other energy generation methods. The International Electrotechnical Commission has provided technical specifications for developing wave energy resource assessments and characterizations, but it is ultimately up to developers to create pathways for making a specific site competitive.

The present study uses example sites to evaluate the annual energy production using different wave energy conversion strategies and examines pathways available to make WEC deployments competitive. The wave energy resource is evaluated for sites along the U.S. coast and combinations of wave modeling and basic resource assessments determine factors affecting the cost of energy at these sites. The results of this study advance the understanding of wave resource and WEC device assessment required to evaluate commercial-scale deployments.
Structural Reinforcement and Leak Sealing with Composite Materials
Authors: Di Cesar Silva George , Georg Fink Thomas , Almeida Bordieri Pedro , Missao Watanabe Mauro , Jhoni de Oliveira Maicon
Published: April 2019

Objectives/Scope

This document presents the application steps of the repair and structural reinforcement system with high-performance polymer and composite material. Without the need to shut-down the offshore platform, this technology is based on ASME and ISO international standards with high safety and applicable in classified areas where hot-work permit is not obtainable.

Methods, Procedures, Process

The methods and procedures are applied and carried out exclusively for each application, after a judicious risk assessment. Recently, a 14" super duplex pipe carrying seawater line, operating at 8 bar pressure, on an oil platform located in Ghana showed active leak. In order to carry a conventional repair, (replacement of the problematic section or conventional hot welding) the shut-down of production would be necessary. Furthermore, the conventional method was not applicable due to the potentially explosive atmospheric conditions. Based on Part 4 of the ASME PCC-2 standard, the repair system was engineered to a 10-year lifespan and carried out with absolute safety. The procedure consists of a surface preparation, leak containment and structural reinforcement on the defective area of the pipe. All the steps in the aforementioned procedure were cold-work type and without the need to shut-down, therefore without loss of production. The equations used to calculate the thickness and length of the repair system with composite material, as well as the risk assessment, were in accordance to the referenced standards.

Results, Observations, Conclusions

The repair system was applied with success without the need to shut-down the production and was considered permanent by ABS. The hardness of the composite, measured after 24 hours, indicates full cure of the repair as predicted by the procedure and quality standards. Therefore, the leak was 100% sealed and the area was structurally reinforced in line with the engineering plan and without any loss of production.

Novel/Additive Information

The integrity of aging offshore assets is a common global problem due to the constraint of concurrent activities in a production environment. This methodology using composite materials in association with asset integrity management without shutdown production has gained recognition to be a long-term solution. The implementation of the repair and structural reinforcement system with high-performance polymer and composite material provides cost reduction, significant health, safety and environmental advantages as it enables immediate attention for the defect, on top of the benefit to avoid the loss of production.
Beneficial Wave Motion Response for Wind Turbine Support TLPs with Synthetic Rope Tendons
Authors: Hsu Wei-Ting , Litton Richard , Vasala Haritha , Anderson David , Sheppard Robert
Published: April 2019

As the offshore wind industry matures and projects begin to expand to deeper water regions, various floating systems are being considered to support wind turbines. This paper explores the feasibility of a Tension Leg Platform (TLP) support system anchored with synthetic rope tendons attached to a gravity base template to provide a platform for a wide range of water depths with acceptable operating nacelle accelerations.

In this paper, the NREL 5MW wind turbine is selected in order to provide a comparison to previous studies of steel tendon TLPs. A fully-coupled numerical modeling tool is used to assess the effects of extreme irregular sea loads on the TLP. A series of numerical simulations are carried out to compare the response of a Single Column (SC) TLP for three different water depths and three different environments. The responses are compared with the steel tendon model.

The use of synthetic rope tendons potentially offers more efficient installation options and enlarges the range of acceptable water depths. The use of a gravity base/suction pile foundation may improve the installation cost and schedule. The fully coupled nonlinear, time domain analysis tool used provides a unique look into the fully operating wind turbine under stable motion characteristics of the TLP.
Offshore Project Standardization: Harmonized Set of Standards and Specifications for Cost Reduction in Offshore Projects
Authors: Lee Hoseong Daniel , Chakala Mathew
Published: April 2019

Many oil majors have their own in-house safety standards, engineering and design practices. At the same time, industry groups and various local authorities have developed their own codes, standards and recommended practices. On top of this, each classification society has its own set of rules for building offshore structures and machinery.

As a result of the various requirements, highly complex specifications unique to each project are developed. The offshore project standardization effort seeks to find acceptable common ground between the numerous individual standards and requirements to reduce costs and increase efficiency in offshore engineering, procurement and construction (EPC) projects. As part of the standardization project, the specifications for the major topside equipment were developed to simplify procurement of machinery packages. In addition, bulk materials, outfitting design and the best practices for welding and inspection were standardized for construction efficiency.

A gap analysis was performed, comparing executed project specifications, industrial standards, and international and local regulations. The specifications were then harmonized focusing on construction efficiency, compatibility and operational maintenance, and with the safety requirements. A major driver in this activity was to adopt marine practices for offshore application without compromising safety and quality. Feedback on the process was obtained from an advisory group made up of owners, operators, engineering companies, vendors and shipbuilders.

Two standardization cases are presented as examples. The first is the standardization of topside piping material which resulted in the enhanced compatibility of materials and provision of greater construction flexibility, addressing material chemical composition, sour service application, wall thickness, test procedures and acceptance criteria. Secondly, a harmonized specification was developed for an air compressor package which meets the requirements for the design, inspection, testing, installation and commissioning for offshore application. The proposed standard project specifications help to reduce the potential for a manufacturer to misunderstand an owner's unique standards and requirements, and provide an opportunity to bring about cost reduction especially in unnecessary engineering and documentation.
Effect of Thermo-Physical Properties on Multiphase Flow Modeling
Authors: Erickson Dale D , Pusard Matthew Michael Farrell
Published: April 2019

An important, but relatively unexplored topic in multiphase flow modelling is the effect of thermos-physical properties on multiphase models. This is relevant in the context of 1-D modelling of large multiphase systems such as pipelines from subsea wellheads to the onshore processing facility. Millions are spent on multiphase flow simulation models, but not enough attention is given to the thermophysical models which can affect the results just as much as multiphase flow correlations.

A wide variety of field data have been compared to various multiphase models. More often, the multiphase flow model needs custom "Tuning" of the thermophysical properties to closely match the production data from the field. In this presentation, we discuss the impact of water content, composition of hydrocarbons, gas to oil ratio (GOR), surface tension, liquid density, and fluid enthalpy.

Typically, improving accuracy of these properties will increase the prediction of multiphase models significantly. For example, error in the temperature prediction can be reduced from 10 C to 1 C, pressure uncertainties from 25% to 5%, and liquid holdup from 30% to 10%.This presentation will present examples of each using field data, before and after this improvement. This paper will also discuss using four different equations of state (EOS) for the calculations of different properties: phase equilibrium, gas density, liquid density, and enthalpy departures. This approach is used instead of the traditional approach of using 1 cubic EOD for all properties. This talk will also present error uncertainty bands for some commercial thermodynamic simulators and their corresponding impact on the multiphase flow predictions.

Among all the properties mentioned above, surface tension needs particular attention since most of the multiphase models use it as a parameters. However, it is seldom measured for most of the hydrocarbon systems. Off-the-shelf thermodynamic simulators are not able to predict the surface tension accurately because of the variable content of naturally-existing surfactants in the hydrocarbon fluids. Hence, through this presentation, we raise the question if this is the limitation of the multiphase models for design, especially since most multiphase flow correlations have not been compared over a wide range of surface tensions.
Gas Hydrate Prospecting and Characterization
Authors: McConnell Daniel Russell
Published: April 2019

Data acquired from major gas hydrate field programs over the past 20 years has led to much better understanding of the distribution of gas hydrate on the continental margins and how to detect them. Gas hydrate systems are extensions of the conventional hydrocarbon system but are much more closely related to biogenic gas systems. The temperatures at which most biogenic gas is generated is mostly below the base of gas hydrate stability which means that most biogenic gas has to migrate into the gas hydrate stability zone and has to be at levels in excess of solubility for gas hydrates to form. Gas hydrates had been considered ‘self-sealing’ but evidence from pressure cores and laboratory experiments indicate that gas hydrate deposits may need local seals. Detection of gas hydrates though seismic and other remote sensing methods has been demonstrated through drilling and coring programs. The GC955 site in the Gulf of Mexico is used as an example to demonstrate exploration concepts, through basin models, seismic detection, and drilling and coring results. Data from other locations are also discussed. A review of remote sensing data that could be used to delineate and quantify gas hydrate deposits is presented with an emphasis on low frequency exploration 3D seismic for imaging gas hydrate deposits at the base of gas hydrate stability.
FTMC Turbine: A Marine Turbine for the Gulf Stream Current Off the Coast of Florida
Authors: Moreu Jaime , Barrett Robert , García-Morato Ricardo , Dragan Radu Stefan , Aguado Eduardo , Cooke Glynn
Published: April 2019

This paper describes a marine turbine concept specifically designed to harness the energy from the Gulf Stream Current. This current achieves, at some points off the East coast of Florida, a speed that ranges between 2 and 4 knots in the first 100m of water depth, for 85% of the time. A device in this region shall be at least 40m deep to avoid navigation and wave interference. Since in these fast regions the seabed is 200 to 500m deep, moored solutions are the most feasible option.

Moored turbines require buoyancy to allow the device to be located at the optimal depth quite easily. In our design the buoyancy is given by a nozzle, which does not obstruct the flow but accelerates it. Consequently the blade size is reduced and protected from shock.

The mooring consists of a tension-tether arrangement that significantly reduces the vertical displacements, minimizing the pressure variation in the air tanks. This tension-tethered mooring also reduces the footprint and can be arranged to allow the turbine to passively turn into the current direction, increasing the capacity factor. The device is installed by controlling the nozzle ballast water and air pressure, and by attaching the mooring line to a concrete block on the seabed. If maintenance is needed the operation can be reversed, helping to reduce OPEX.

The combination of a TLP (tension leg platform)-like mooring and a robust floater arranged as a nozzle makes the concept feasible. A magnetically-geared Pseudo Direct Drive (PDD®) generator ensures a robust, direct-drive, high torque, low speed and highly efficient solution that can operate in the inherently rough immersed conditions.

The design has been validated in 2018 through prototype testing at INTA-CEHIPAR model basin in Spain. Thus, the concept as an offshore alternative energy converter has been confirmed. The small-scale demonstrator is designed for 600 Nm and 6 kW, with rotational speeds of up to 100 rpm. During the tests, the generated power has been measured at different generator and current speeds with the device fixed. The levels of generated power and efficiency agree with the CFD calculations. Furthermore, the stability of the marine turbine has also been confirmed. Several configurations of mooring lines and stabilizers have been tested to ensure that not only the unit is self-steerable, but that it also minimizes Vortex-Induced Motions.

Regarding the business case, competitive values of the levelized cost of energy (LCOE) can be achieved because of the high power density available in the selected coastal locations combined with high capacity factors. This overcomes the higher capital expenditure (CAPEX) per MW of each unit, because it is fully immersed, compared to offshore wind solutions.

The project has been co-financed by the Eurostars Program.