bluuebunny/crossref_metadata_2025 huggingface dataset:
Cash is King - Repurposing Marginal Assets to Reduce Floating LNG CAPEX
Authors: Tierling Kenneth Shane
Published: August 2021

Objective / Scope

With renewable energy sources not currently able to move energy around the globe and forming small portions of the total global energy supply, it has fallen upon hydrocarbon sources to form the backbone of global energy movements. Hence, the recent energy demand decline, along with policy, have disproportionately impacted world-wide petroleum and LNG pricing. The impact on Floating LNG has been a heightened demand for capital efficiency, required to achieve final investment decision.

A business case specific means of reducing FLNG CAPEX, has been repurposing marginal assets. Starting with a breakdown of the cost components of an FLNG facility, this paper will provide examples of the inclusion of preexisting assets into FLNG projects to reduce capital cost. The paper will wrap up with other opportunities for cost savings, to stimulate thought.

Methods, Procedures, Process

Floating LNG (FLNG) technologies have been deployed to monetize mid-sized offshore gas reservoirs, avoiding constructing a sub-sea gas pipeline to a land-based LNG facility and export jetty. Containing the processing to an oceanic environment also reduces the impact on indigenous peoples as well as terrestrial flora and fauna. FLNG facilities also have the potential of serving multiple offshore fields over the life of the facility, thereby reducing the minimum size field that can be economically monetized.

Interest in FLNG continues, despite the current slump in energy prices, however these challenging times are refocusing efforts on reducing the capital cost of FLNG. This paper will explore recent capital cost trends in LNG, with a focus on floating LNG, examples of realized opportunities to reduce CAPEX, and further scope for reductions.

Results, Observations, Conclusions

The readers will take-away from this paper a deeper understanding of:

Recent trends in CAPEX for LNG, and specifically FLNG Where significant opportunities lie for cost reduction Examples of the reuse and repurposing of marginal assets to reduce cost of FLNG facilities Areas to be explored for future capital reduction

Novel / Additive Information

This paper pulls together disparate threads into a coherent whole, providing visualization of the trends and examples of realized opportunities.
Task Scheduling for Subsea Flexible Pipes Decommissioning
Authors: Bressan Robert da Silva , Artigas Danilo
Published: August 2021

Subsea flexible pipelines removal is subject to order restrictions, mostly caused by crossings. It is proposed to create a computational algorithm to design an optimal order of vessel intervention over a field. A real field was studied, and, from it, the mathematical base model was created upon graph theory, with great correlation with the minimum feedback arc set problem. Vessel movements were discretized and reduced to removal, reposition, and cut, leading to a state search. A-star algorithm was implemented to guide the search for the solution. Then, the complete algorithm was built, tested in a minimal environment, and finally applied to the real instance. To improve performance, a beam search filtering was envisioned, using seven ranking functions. Constructed model is suspected to be NP-hard, by correlation to minimum feedback arc set problem, leading to a large space search. Instances containing under 100 crossings were solved optimally, without needing any assistance. After implementing the heuristics and beam search, solution time was lowered by about 20 times, demonstrating the effectiveness of the technique. Also, ranking functions for pipe repositioning based on crossing count led to better results than crossing density. For cutting, an approximation based on feedback arc set was used. GreedyFAS was employed and gave satisfactory results. Bigger instances containing around 3000 crossings could not be solved optimally in a reasonable time, even with the heuristics. Improvements in A-star estimation function and bound the solution branches might lead to an optimal solution for these larger instances. Model proposed simplifies the operational order decisions and helps build the scheduling of operations. As it is based on state search, other aspects in logistics, vessel capacities and steps in decommissioning processes may be added, adjusting the neighboring weights and branching, keeping the same core.
The Liza Field: From Discovery to Development
Authors: Austin Nicholas , Das Mita , Oyerinde Adedayo , Elkington Elizabeth
Published: August 2021

In May 2015, Liza-1 encountered more than 90 m (295 ft) of high-quality oil-bearing Upper Cretaceous deepwater sandstones. Immediately, the >1 billion barrel Liza field began on its path from discovery to development.

Following the Liza-1 discovery, ExxonMobil and the Stabroek Block co-venturers, Hess Guyana Exploration Limited and CNOOC Petroleum Guyana Limited, undertook a blockwide 3D seismic survey, the largest performed by ExxonMobil at that time, to better delineate the resource potential. Subsequent appraisal drilling built confidence in the performance and connectivity of the reservoir while providing calibration data to inform the development. The initial appraisal well was the "inverted-Y" Liza-2 drilled in early 2016, which comprised an original hole and a sidetrack. A comprehensive evaluation program was implemented with conventional coring of both the original hole and the sidetrack to provide reservoir calibration critical to field development. Furthermore, a production well test was performed on the Liza-2 sidetrack to build confidence in dynamic performance and connectivity assumptions. The Liza-3 appraisal was then drilled down dip of the Liza-1 and −2 to confirm static connectivity across the field.

A scenario modeling and simulation approach was implemented at Liza to capture the full range of plausible realizations that could represent the field. The scenarios were measured against the incoming data (Liza-2 and Liza-3) when acquired, and scenarios with greater alignment to the data continued to be pursued while others were moved to a much lower probability of occurrence. This multi-scenario approach was utilized to develop an integrated reservoir model that allowed for depletion plan optimization across a range of subsurface scenarios within flow assurance constraints, ultimately supporting the final investment decision (FID) for the Liza Phase 1 project in 2017, just 25 months after the Liza-1 discovery.

Following FID, advanced, proprietary Full Wavefield Inversion seismic reprocessing and high resolution 4D baseline seismic acquisition and processing have been utilized to enable continued optimization. The path from discovery to development culminated in December 2019 with the commencement of production from Liza Phase 1 less than 5 years after the first deepwater oil discovery in Guyana.
Center of Excellence: Leveraging Data to Reduce Incidents on Offshore Oil and Gas Assets
Authors: Bayon Le Ronan , Boyd Leah
Published: August 2021

This paper presents a novel approach to finding solutions to unsafe work practices in oil and gas environments—from manufacturing facilities to offshore platforms. The ‘Center of Excellence’ approach is a stepwise process for classifying safety events and harnessing data to reduce incidents during offshore oil and gas E&P activities.

The approach includes identifying focus topics related to unsafe practices, forming cross-functional teams with significant field or impacted personnel participation, developing and implementing measures, utilizing the hierarchy of controls to mitigate the issue, and raising company-wide awareness through training and targeted information campaigns.

The Center of Excellence process gives top priority to those activities in order to reduce the highest severity and most frequent safety incidents. The teams are then able to more clearly identify feasible solutions, including engineering controls, training, campaigns, and procedures to contain the hazards.

The active engagement and involvement of frontline employees who either work in the field or on the factory floor is critical to understand the daily hazards of their work activities and the success of the Center of Excellence approach. With these employees acting as a champion of the developed solution, other workers are more likely to accept and adopt it in their daily routine.

This paper reviews practical examples of how the Center of Excellence approach has led to safer practices in the workplace. Examples include improved safety measures for using tightening tools, which led to more than 50% reduction in hand injuries and other safety incidents. A recent example of using the approach to develop safer practices during manual handling of loads (MHL) is also presented. The examples highlight the benefits of bringing multifaceted teams and multiple industry-accepted safety concepts together to resolve common work safety challenges, which can serve as a blueprint for oil and gas companies to reduce incidents across their enterprise.
Protective Barrier Wall Response to Sequential Blast and Fire Events
Authors: Smith Hunter
Published: August 2021

Blast and fire-resistant barrier walls are often required on offshore platforms to protect from accidental events. A wall structure designed for a probabilistic explosion event typically relies on inelastic response and plastic deformation to maintain a lightweight, efficient design. Design guides for such structures do not explicitly address how to account for the effects of interaction of blast and fire loading on structural performance and design acceptance criteria. If a wall assembly is required to provide rated fire and gas protection after an explosion event, it is generally assumed that structural integrity is maintained due to temperature increase limits (140°C) from the H-60/120 rated fire protection on the wall. This paper investigates the validity of this assumption for a typical offshore barrier wall designed to undergo permanent deformation during an initial blast event.

The study was performed utilizing non-linear dynamic finite element analysis (FEA). FEA allows for design iteration, structural assessment, and validation against extreme load scenarios when testing of full-scale assembly may not be feasible. A typical wall structure was first analyzed for blast loading by non-linear dynamic structural analysis. Thermal loading from a subsequent hydrocarbon fire was then applied to observe the structural response in the post-blast damaged condition. Based on the rated temperature range, the resulting thermal expansion in the wall panels induces large stresses at the interface between wall panels and supporting steel. Non-linear FEA confirmed that yielding occurs which may increase existing plastic strains beyond design limits at locations of high stress concentration. Therefore, it is prudent to consider thermal performance in the design process, especially regarding connections and penetrations.
Buzios Presalt Wells: Delivering Intelligent Completion In Ultra-Deepwater Carbonate Reservoirs
Authors: Schnitzler Eduardo , Gonçalez Luciano Ferreira , Roman Roger Savoldi , Marques Marcello , Gutterres Fábio Rosas , da Silva Manoel Feliciano , Castilho Carlos Alexandre Belo
Published: August 2021

This paper describes the challenges faced on the deployment of intelligent well completion (IWC) systems in some of the wells built in Buzios field, mostly related to heavy fluid losses that occurred during the well construction. It also presents the solutions used to overcome them. This kind of event affects not only drilling and casing cementing operations, but may also prevent a safe and efficient installation of the completion system as initially designed.

The IWC design typically used in Brazilian pre-salt areas comprises cased hole wells. Perforation operations must be performed before installing the integral completion system, as it does not include a separation between upper and lower completion. Therefore, the reservoir remains communicated to the wellbore during the whole completion installation process, frequently requiring prior fluid loss control as to allow safe deployment. Rock characteristics found in this field make it difficult to effectively control losses in some of the wells, requiring the use of different well construction practices that led to the development of some new well designs.

The well engineering team developed a new well concept, where a separated lower completion system is installed in open hole, delivering temporary reservoir isolation. This new well architecture not only delivers reduced drilling and completion duration and costs, but also provides the IWC features in wells with major fluid losses. This is possible by the use of multiple managed pressure drilling (MPD) techniques when required, which were considered since the initial design phase. Safe and effective construction of some wells in pre-salt fields was considered not feasible before the adoption of MPD solutions, both for drilling and completions.

Other important aspects considered on the new well design are the large thickness and high productivity of Buzios field reservoirs, as well as the need of some flexibility to deal with uncertainties. Finally, the new completion project was also designed to improve performance and safety on future challenging heavy workover interventions. The well construction area has gradually obtained improved performance in Buzios field with the adoption of the new practices and well design presented in this paper.

The new solutions developed for Buzios field have set a new drilling and completion philosophy for pre-salt wells, setting the grounds for future projects. The improved performance is essential to keep these deepwater projects competitive, especially in challenging oil price scenarios. One of the groundbreaking solutions used is the possibility of installing the lower completion using managed pressure drilling techniques.
Flexible Pipes Subjected to SCC CO2: Review and Means to Increase Reliability on Service Life Applied to Brazilian Pre-Salt Fields
Authors: Brandao Mauricio , Pires Fabio , Poloponsky Ingrid , Santos Fabio , Lopes Diogo
Published: August 2021

Flexible Pipes were widely used in Brazil offshore developments and the challenge on overcoming increasing water depths, high pressures and fluids with high contaminants was always present. In 2017 a new failure mode, called SCC CO2 was disclosed bringing such disruption in the use of this equipment since, at that time, the conditions observed in Brazilian Pre salt were like the "perfect storm" for the failure mode to happen. It had high concentrations of CO2, therefore high permeation in the anulus, high stresses and the possibility to have anulus flooded as result of an outer sheath breach or even due to permeated water. These were the triple conditions needed to have the failure, considering that all metallic material used in the pipe were subjected to this phenomenon.

Since the discovery was made, several test campaigns to better understand and replicate the phenomena started. They covered pipe retrieved from field dissection, several small-scale materials testing, and fracture mechanics to create reliable crack propagation calculations. There were 3 mains focus areas; to understand how to deal with the installed fleet, to define the conditions in which a crack would appear and define, using fracture mechanics, how long a crack would take to break the wire. In other words, it was intended to define what is the remaining service life.

As a result of this investigation some initial beliefs like that all materials were subjected to the phenomena and that a solution was far away were somehow reduced and reshaped. There was also the initiative to embark on technology for detection of the anulus condition, mainly to define if it is flooded or not. Some ROV inspection means were added to the endfitting and some sensors were added to the interconnected pipe sections that allow conditioning monitoring or inspection from the floating unit, not using a ROV.

This paper will cover the improvements done since the disclosure of the phenomena in 2017, reviewing what is known about it so far, what is still to be discovered and how the results achieved to date can contribute for a more reliable and longer service life for the flexible pipes to be applied in a rich CO2 environment.
Buzios: The Largest Ultra-Deepwater Oilfield to Date
Authors: de Oliveira Jose Olavo de Andrada Ignacio , Tavares Pedro Lemos , da Silva Victor Costa , Lima Ivan Noville Rocha Correa , Britto João Francisco Fleck Heck , Hernalsteens Thierry , Kahn Marcio
Published: August 2021

The purpose of this paper is to present a general overview of the Buzios field development plan, projects’ features, and main achievements so far.

The development plan adopted a strategy to pursue the balance between acceleration and cash flow optimization, to maximize the return on the huge investment on the block acquisition, and the risk management related to developing several Greenfield Projects simultaneously. To reduce reservoir uncertainties, a comprehensive data acquisition plan was crafted and implemented considering: (a) seismic acquisition, (b) drilling, logging and testing several exploratory and appraisal wells, (c) massive rock and fluid data sampling along the reservoirs, (d) execution of one Extended Well Test and three Early Production Systems.

Additionally, the basic design of wells, subsea systems and Floating Production Storage and Offloading ("FPSO") provided flexibility to cover remaining uncertainties yet present in the Transfer of Rights ("ToR") scope, which allows up to 3,150 billion barrels of oil equivalent ("boe") to be produced. This led to technological challenges that needed to be addressed during project planning. We believe that the innovative solutions applied enhanced currently available technologies and delivered an important legacy to the offshore oil and gas industry.

Finally, the results obtained so far, with the ramp-up of Buzios projects 1, 2, 3, and 4 provide evidence of the successful adopted strategy and reinforce the decision of deployment of a fifth FPSO under the scope of the ToR contract. The strong results of the asset led to the acquisition of 90% of the Transfer of Rights Surplus ("ToR+"), together with CNOOC Petroleum Brasil Ltda. (5%) and CNODC Brasil Petróleo e Gás Ltda. (5%), which now paves the way for a second wave of development, including the deployment of up to seven additional FPSOs.
Hybrid Conductor-Supported Tripod Platform: Brownfield Design Perspective to Unlock Production Capacity
Authors: Ozkul Selma Nur , Huang Wen-Xing , Taxy Stephane
Published: August 2021

Objectives/Scope

Oil and gas companies have shifted their investment priorities to low CAPEX brownfield projects in response to historically low oil and gas prices. One approach is to increase the production by drilling new wells and tying them back to existing tripods. However, existing tripods have limited as-built design data and are usually near the allowable structural capacity limits. This study introduces a novel concept of the "hybrid conductor-supported tripod" to support the new wellheads. This approach minimizes the need to modify the existing tripods.

Methods, Procedures, Process

The hybrid conductor-supported tripod utilizes the new well conductors to support the wellheads, extends to the existing tripod topside to support the production facilities, and resists lateral loads from the new wellheads. Such hybrid conductor-supported tripod takes advantage of the axial compression capacities of the new conductors while its lateral resistance is provided by integrating only the new topside with the existing tripod's topside. Thus, the underwater structural modifications of the existing tripods are minimized.

Results, Observations, Conclusions

Design and construction challenges commonly encountered during the design phases of brownfield projects include: 1) lack of tripod jacket and foundation as-built data, 2) need for bracing the new conductors to the existing jacket underwater due to buckling and vortex issues, 3) as-built conditions of the tripods are already near their structural capacities. The design and construction issues experienced in low budget and tight schedule brownfield projects are alleviated with the use of a hybrid conductor-supported tripod. A parametric study was conducted to identify the minimum conductor pipe diameters needed for hybrid conductor-supported tripods at various shallow water depths in benign environmental conditions. The in-place conditions of several existing tripods were investigated before and after the hybrid conductor-supported tripods were integrated with the existing tripods. Using hybrid conductor-supported tripods enable production increase on existing facilities with minimal CAPEX investment. This is accomplished by: 1) utilizing existing tripods to increase production, 2) mitigating the need for as-built data, especially underwater jacket data, 3) eliminating additional axial loads on the existing tripods, 4) implementing minimum deck extensions on the existing tripods.

Novel/Additive Information

The hybrid conductor-supported tripods provide the structural expansion need for the new wellhead facilities while keeping the existing tripods in their as-built conditions. Reducing the need for the current condition and the exact as-built underwater information of the existing tripods will accelerate the execution of the low budget and tight schedule production increase brownfield projects.
Validation of Spectral Fatigue Assessment of a West-Africa FPSO Using Full-Scale Measurements
Authors: Andoniu Alexandru , de Lauzon Jérôme , Hageman Remco , Aalberts Pieter , L'Hostis Didier , Ledoux Alain
Published: August 2021

In order to ensure structural integrity and safe operations, fatigue assessment of structural details is a key aspect of design and verification procedures for FPSOs. Spectral fatigue analysis is widely used in the offshore industry to assess damage induced by wave loading. However, the actual fatigue accumulation endured by units in operations usually differs from predictions due to the assumptions made at the design stage. One of the sources of uncertainty is the representation of the encountered sea states. The objective of this paper is to use in-situ measurements as a reference for evaluating the accuracy of spectral fatigue analysis and to investigate the influence of wave energy description on the fatigue assessment.

Structural health monitoring systems have been increasingly used in the last decade in the offshore industry as they constitute a valuable source of information regarding the actual operating conditions, structural response, or encountered environmental conditions. This data can be used to update fatigue assessment in order to determine the remaining service life, understand how the structure is aging, or support for decision making regarding inspections, maintenance, or lifetime extension. The work presented is based on such information gathered during a measurement campaign performed on a spread-moored FPSO in West Africa. Measured strain time histories at several locations on the hull have been used to derive the actual fatigue damage endured by the unit. These damages are compared to the ones determined from spectral fatigue analysis using stress transfer functions obtained from frequency domain hydro-structure computations.

Multiple analyses have been performed to evaluate the impact of different sources of statistical wave data and wave energy descriptions on the fatigue assessment. The wave conditions used originate from wave buoy measurements and hindcast data. Overall, the good agreement between full-scale measurements and calculations confirms the suitability of spectral methods for determining fatigue damage. When incomplete information is available, which is often true in the case of wave statistics, assumptions have to be made regarding parameters such as spectrum shape or wave spreading. However, using the full description of wave energy spectra, if available, can be a way of reducing uncertainties and removing unnecessary assumptions in such analysis. The results of this work show how fatigue assessment can be improved by gaining insight into the different sources of uncertainty, notably the sea state representation. With increasing focus on digital solutions, these results show realistic potential for virtual hull monitoring solutions based on accurate numerical models and realistic representation of wave conditions.
Buzios Drainage Strategy: A Combination Of Reservoir Characterization, Risks Mitigation And Unique Contract Features
Authors: Silva Victor , Moliterno Ana , Araujo Carlos Henrique , Pimentel Francis , Melo Jose Ronaldo , Falcao Claudio , Pessoa Thiago
Published: August 2021

Petrobras acquired the right to produce 3.058 billion boe under the Transfer of Rights (ToR) in Buzios field, which still has a recoverable surplus, recently auctioned by the Brazilian Petroleum Regulatory Agency. Properly planning the production development of a supergiant field and under two tax regimes, requires a large multidisciplinary effort of data acquisition, characterization and modelling.

Located in the Santos Basin Pre-Salt Pole, the Buzios field is a deep-water supergiant that has a large thickness of carbonate reservoirs, with significant areal and vertical variation. The presence of faults, fractures, karsts and other diagenetic processes adds complexity to the field, which motivated the development and implantation of industry innovations to enable its development. The presence of high levels of CO2 and H2S in the reservoir fluid, the risk of inorganic scaling and asphaltene deposition and risks of early fluid channeling and low sweep efficiency due to the aforementioned geological complexities are challenges that need to be addressed.

One of these challenges is to ensure a better seismic data for the reservoir characterization. The 3D seismic data from a streamer acquisition did not have sufficient quality for this. The geological complexity of the field, the great reservoir depth and mainly the very irregular topography of the overlying evaporitic sequence indicated the need for rich azimuth seismic data. This led to the world's largest ultra-deep water seismic survey using Ocean Bottom Nodes (OBN) technology.

This paper will address the static and dynamic data acquisition from the wells and the Early Productions Systems (EPS), as well as the challenges that arose and were faced by Petrobras through technology and innovation, and the complexity of the reservoir dynamic modelling. Furthermore, the OBN seismic acquisition in Buzios will be discussed in more detail, as well as the frontier that this acquisition opens to the development of the field.
The Autonomous Inflow Control Valve Design and Evaluation Criteria Along with Well Performance Review for Multiple Installations Across the Globe
Authors: Kalyani Tejas , Aakre Haavard , Mathiesen Vidar
Published: August 2021

Many wells across the globe have been installed with Inflow Control Device (ICD) technology to balance the production across the production interval, addressing some of the challenges associated with horizontal and deviated wells. Nevertheless, ICDs have limitations with restricting unwanted fluids upon breakthrough. Autonomous Inflow Control Valve (AICV) technology functions similar to an ICD initially (i.e., balancing flux across the length of horizontal wells, effectively delaying breakthrough) but provides the additional benefit of shutting off the flow of unwanted fluids upon breakthrough. This paper will present comprehensive AICV completion design workflow along with multiple case histories highlighting the reservoir management benefits of the AICV technology in mitigating un-wanted inflow of water and gas and delivering improved oil production and recovery.

Like other AICDs (Autonomous Inflow Control Device), AICV can differentiate the fluid flowing through it via fluid properties such as viscosity and density at reservoir conditions. However, AICV's performance is much more effective due to its advanced design which provides further benefits using both Hagen-Poiseuille's and Bernoulli's principles. AICV technology is based on the difference in the pressure drop in a laminar flow element (LFE) compared to a turbulent flow element (TFE) and has a capability to shut-off the main flow autonomously when an unwanted fluid such as water or gas breakthrough occurs. Thus, reduces well water cut (WC) and/or gas-oil ratio (GOR) significantly. Rigorous single-phase and multiphase flow-loop tests have been conducted covering a wide range of fluid properties to characterize the AICVs flow performance. Extensive plugging testing and accelerated erosion tests have also been conducted. This paper presents some of these flow performance analysis and testing results. Furthermore, the paper will also discuss in detail a reservoir-centric AICV completion modelling and design workflow.

Finally, this papers also discuss in detail AICV well performance installed in a light oil as well as in heavy oil reservoirs and how operators achieved higher OPEX saving as well as higher ultimate recovery (UR) from the wells due to prolonged as well as significant reduction in water cut and/or lower GOR.

The AICV design methodology and performance evaluation analysis is presented through several case studies. The analysis takes into account the whole cycle: from flow loop testing to characterization, reservoir modelling, optimized AICV completion design and post-installation well performance to evaluate the AICV technology benefits.
Aerial Robotic Systems Drones for Contact-Based Ultrasonic Wall Thickness UT Measurements at Height
Authors: Dahlstrom Robert L.
Published: August 2021

The use of aerial robotic systems that physically contact oil and gas structural assets to obtain measurement data in offshore and marine environments carries unique challenges and operational variables. The objectives of this paper are to demonstrate, with examples, how these aerial robotic systems afford safer, cheaper, and better nondestructive testing (NDT) measurement collection methodology and allow more robust insight into assets conditions than the slower, less safe, and more expensive manual method.

To take NDT measurements such as Ultrasonic Wall Thickness (UT) Measurements at height, currently one needs to utilize a lift, ladders or other solutions to reach areas on certain assets. This can be both dangerous, due to the possibility of falls, and time consuming. Utilizing an aerial robotics platform for contact based (not visual) NDT measurements such as Ultrasonic Thickness (UT) allows workers to remain safely on the ground. Drones, with robotic arms, have the potential to improve inspection, testing and data collection. This paper explores an aerial robotic system that flies up to a structure with a metal sub-straight, then under full autonomous software control, touches a UT measurement probe to the target and records the measurement data compliant with American Petrolium Institute (API) and other standards.

The use of aerial robotics systems for NDT is still a new and novel application utilizing existing technologies such as electronic measurement readers, drones, etc. with a system of complex integrations that allows for a better application of science. Aerial Robotic NDT systems have the potential to improve the inspection, testing and data collection aspects of coated and uncoated assets, in part, by making the NDT measurement process easier and safer thus allowing for more frequent measurements and/or a larger quantity of measurement samples.

When possible, working at heights should be eliminated as part the hierarchy of fall protection stipulated by both OSHA and ANSI. For this reason alone, the use of aerial robotic systems is important now and in the immediate future Oil & Gas infrastructure, including Offshore. This paper intends to provide readers an awareness of this new technology as well as provide information about its efficacy, limitations and operational requirements.
The World Deepest Electrically Heat-Traced Flowline
Authors: Hurault de Ligny Florent , Cuau Thomas , Immel Stephen
Published: August 2021

Electrical heat tracing technologies for flowline applications have been in development phase for some time. Yet in recent years, the efforts to deploy this technology on real life applications have intensified, leading to several projects in the industry simultaneously adopting this solution. As often seen with technology development, implementing the serial number 1 of a technology requires one project with favorable conditions and parameters, but also the stakeholders willingness to face the challenge associated to being first, and having to cross the final gap between the qualification program and this real life application. This paper presents how a specific project met all the conditions to be the first to select and implement a deepwater EHTF® (Electrically Heat-Traced Flowline) solution.

This paper presents the Project from the concept selection phase, to the execution and offshore installation of the final product. This provides an overview of why this technology was selected, and how the Project was executed, with a focus on the main challenges encountered and the associated solutions.

The concept selection phase for this two-well development consisted of comparing subsea tie-in architectures to tieback architectures using one or several new risers. The EHTF® emerged as the highest value solution, offering the best compromise between technical, economical, risk and schedule criterion, as it enabled single line tieback, while significantly reducing the operational risks associated to such architecture. A FEED was launched to further define and accurately estimate the concept, in order to reach FID. Close collaboration between the Operator and the Contractor at every step of the process allowed the solution to be selected and developed in a fast track manner while enabling the Contractor to provide an optimized, tailor-made solution.

The project execution involved many work sites, including the Vigra spoolbase in Norway for EHTF® fabrication, as well as the Seven Vega, which was a brand-new addition to the pipelay vessels fleet at the time of the Project. Many challenges arose during the project execution, as the qualification program was being completed, but adequate solutions were developed, allowing the Project to continue its course.

Obviously, there were many lessons learned along the way, which will feed into further product development plans, in order to improve its technical performance and competitivity. Heat tracing solutions offer great opportunities for single line long tieback development which often come with elevated operating risk profile due to complex wax and hydrate management. Enhanced thermal performance of resistive heating systems makes it possible to operate with low power consumption, which is a key in today's world of energetic efficiency.
Introducing an Innovative Perfluoroelastomer Cross Linking Technology: Achieving Superior Chemical Resistance and Thermal Stability
Authors: Alvarez Jimmy , Bish Christopher J. , Rodriguez Andres
Published: August 2021

Objectives/Scope

Perfluoroelastomers are a class of synthetic elastomers that provide extraordinary resistance to oils, chemicals, and heat. The outstanding thermal stability and excellent corrosion resistance of these materials is dependent on the perfluorinated polymer chain, and the absence of unsaturation. However, the cross-link which is necessary to impart elastomeric properties must also share those stability traits. Unfortunately, designing a suitably inert cross-link is technically difficult to achieve and consequently it has not been possible to provide the ultimate in perfluoroelastomer properties. This paper is a review of the cross-linking chemistry of perfluoroelastomers and highlight a novel and patented cross-link which combines broad chemical resistance and superior thermal stability.

Methods, Procedures, Process

Several perfluoroelastomers formulations were selected and tested using representative standardized test methods to quantify their performance. The testing included compression set resistance, swell in fluids, and compression stress relaxation. In addition to the testing, chemistry of the cross-link was explained and how it is related to the observed performance results. The novel cross-link, triazole, was identified as an improvement versus existing cross-links.

Results, Observations, Conclusions

The testing demonstrated that previously available perfluoroelastomer cross-link chemistries display compromises in overall performance. For example, it had not been possible to achieve high thermal stability combined with resistance to almost all fluids. Overall, the data generated showed that the newly developed triazole cross-link system broadens the performance envelope of perfluoroelastomers and helps to alleviate the compromises of the past.

Novel/Additive Information

The newly discovered triazole cross-link with enhanced chemical and thermal stability enables broader use of perfluoroelastomers in extreme applications.
Significant Reduction of Well System Fatigue by Use of Reactive Flex Joint with Integrated Monitoring System
Authors: Sønåsen Knut Olav , Moe Per Thomas , Hansen Morten , Fjeldstad Dag André , Gustad Halvor , Sadeghi Alireza , Hilley Alexander , Bjørset Arve
Published: August 2021

Operators working on shallow and mid-water depths in rough seas are focusing on reducing fatigue in the upper part of well systems during drilling operations. Fatigue is caused by cyclic bending moments due to wave induced riser and vessel motions. The combined use of a Reactive Flex-Joint (RFJ) and the Well Access Management System (WAMS) has demonstrated significantly reduced fatigue exposure through a reduction in loads, reporting of real-time status and rig positioning advice.

The RFJ is a mechanism mounted on a standard flex joint for easy installation on drilling rigs. It uses a nitrogen gas spring to reverse the flex joint bending moment. The generated opposing moment increases with an increasing angle of the lower flex joint. This significantly reduces the cyclic bending moments in the lower part of the Blow Out Preventer (BOP) and wellhead (WH) system. WAMS is an advanced monitoring system that may be operated as a fully integrated part of the RFJ design. Sensors provide real-time data for flex joint angle, BOP inclination, wellhead- and riser bending moments. The data is used to assess incurring fatigue damage in real-time and for reporting fatigue status after operations.

Two RFJ systems have been in continuous use on two separate rigs during 2020. The RFJ system and WAMS are field-proven and have demonstrated their efficiency in challenging operations in the Barents Sea and the North Sea. The RFJ has been well received in the market due to one-time installation, safe use, significant reduction in wellhead loads, and low operating expenses (OPEX).

Data obtained from the operations have been carefully analyzed and show that the RFJ reduces cyclic loads from 50 to 80% resulting in 30 to as much as 1000 times extended fatigue life of the wellhead. The RFJ efficiency depends on the settings of the system and operational conditions.
A Real Time Fatigue Monitoring Platform for Flexible Risers
Authors: Yuan Jiabei , Hou Yucheng , Wilson Eric , Tan Zhimin
Published: August 2021

Fatigue life of flexible risers is a critical design factor in offshore riser system design. To estimate the fatigue damage, global and local analyses are performed inhouse with inputs from operators. Metocean data, riser properties, vessel or platform RAO data are typical inputs for the fatigue analysis. In addition to the conservatism inherited in the product design methodology and API safety factor 10 for fatigue estimation, the input data may also contain some additional conservatism compared to actual operational conditions as these were estimated/projected from limited time-span of observations or predicted purely from numerical modelling. In combination, these inheriated conservatism permits the feasibility of service life extension of the flexible riser systems.

Many platforms or vessels already have real time monitoring of motions in multiple degrees of freedom and wave/current data. Furthermore, pipe internal operating conditions like pressure and temperature are usually recorded onboard. Compared to the typical input data/assumptions made in predictive analysis, these records are more precisely and directly related to the actual fatigue damage accumulation. With real time data, a more accurate estimation on fatigue performance of riser can be achieved, which could enable the service life extension without compromising the design safety factors.

A special software tool has been developed to calculate the real time fatigue damage of flexible tensile wires. The software is based on product design tools which are calibrated and independently validated with over 30 years installed operational experience. Developed in Python, the software utilizes an OrcaFlex API and a local analysis algorithm in the background. The software can be customized towards different platforms and pipe systems, as well as input data types. Depending on clients’ needs, multiple fatigue hot spots like top end fitting, bend stiffener region or touch down zone can be monitored at the same time. Other parameters like riser real time extreme response or statistical results can also be checked in the software.

This paper summarizes the development of the pipe monitoring system. It is believed that with real time inputs, the software can better assist clients to monitor the pipe fatigue performance and other related riser responses.
Novel Intelligent Pigging Tool For Deposit Inspection Using Electrical Tomography with High Computational Efficiency Enabled Through Neural Networks
Authors: Nissinen Antti , Lehtikangas Ossi , Voutilainen Arto , Laakkonen Pasi , Lehikoinen Anssi
Published: August 2021

Objectives/Scope

Deposition inspection sensor based on electrical tomography has been proposed recently. In this work, a next generation electrical tomography sensor is introduced and a novel mathematical approach for the estimation of the deposit thickness is described. It is essential for the pipeline operators to keep the lines open for smooth flow and high flow efficiency. Deposit thickness, deposit type and location of deposit is required for optimal pipeline cleaning. The usage of chemicals as well as number of cleaning pig runs can be optimized based on the information that intelligent pig is giving.

Methods, Procedures, Process

In electrical tomography, electrodes are attached on the surface of the sensor and excitations are applied to some electrodes and responses are measured from other electrodes. The electrical properties of the medium are estimated based on these measurements. In pigging applications, the distribution of electrical properties between the PIG surface and metal pipe is estimated. The thickness and type of deposit (wax/scale) can be identified from the estimated electrical properties. In the proposed approach the estimation of the parameters is done by using a novel deep neural network based approach. In practice, number of measurements that are analyzed after each PIG run can be hundreds of thousands. The neural network based approach was chosen in order to achieve reasonable computational efficiency (computation time) in real applications with large amounts of data.

Results, Observations, Conclusions

The introduced sensor is for 12-inch lines and designed to be used when the oil line is filled with water. This sensor was tested in a laboratory test line with artificial deposit samples. After these tests and calibration, the sensor is deployed to be used in real pipe line inspections. The major challenges in pipe line runs include the movement of the sensor during measurements, electrical noise and changing excitations. In the neural network model, the position of the PIG is estimated simultaneously with the electrical properties and the effect of all these aforementioned uncertainties are also modelled. Based on the results conclusions can be drawn on the efficiency and performance using neural networks and the high suitability of electrical tomography for deposit mapping.

Novel/Additive Information

In this study, it is shown that intelligent pig based on the electrical tomography can be used reliable for deposit inspection. Furthermore, the computation approach based on the deep neural network is computationally efficient and it is tolerable for measurement noise and other uncertainties in real measurements.
Increasing the Cost Effectiveness of Mechanically Lined Pipe for Risers Installed by Reel-Lay
Authors: Jones Richard Lloyd , Toguyeni Gregory , Hymers James , Tanscheit Peter , Romeu Nelson Bittar , Rao Venu , Banse Joachim
Published: August 2021

The use of mechanically lined pipe (MLP) using a thin liner, i.e. 2.5mm, can provide a more cost effective linepipe material solution relative to a standard 3.0mm liner. This is especially the case for the more expensive liner materials with higher corrosion resistance, including Alloy 625. Thin liners, i.e. 2.5mm, can be used without compromising pipeline integrity and performance, whilst still fulfilling design requirements defined in most pipeline design standards, including DNVGL-ST-F101. The suitability of 2.5mm liner MLP has previously been demonstrated in service over a range of pipeline bundle projects installed with the controlled depth tow method, but not to date for risers installed by reel-lay. This paper presents the details and test results of the qualification programme to support its use for both flowlines and risers installed by reel-lay.

The qualification MLP test pipes, which comprised an outer diameter (OD) 219.1mm × wall thickness (WT) 15.9mm X65 + 2.5mm Alloy 625, were manufactured using established manufacturing procedures and facilities. Reeling and fatigue test strings were fabricated using qualified welding solutions. The fabricated test strings were subject to internal visual inspection and dimensional measurement using laser metrology in order to provide a benchmark for comparison post reeling. The test strings were given a simulated reeling procedure using bending and straightening formers representative of a reel-lay vessel with the smallest reel hub diameter, this being a conservative material straining condition. An internal pressurisation technique, as per standard installation practice for the present pipe lay contractor for MLP, was applied during the simulated reeling procedure. Post reeling the internal laser metrology inspection procedure was repeated in order to confirm the integrity of the liner and to check for the presence of any evidence of liner wrinkling or damage. Subsequently, full scale fatigue testing was performed using the high frequency resonance bending procedure. Testing was performed to ultimate failure to determine the fatigue endurance limit of the thin liner MLP.

Additionally Finite Element Analysis (FEA) was performed to further validate the satisfactory reeling performance of the thin liner MLP. The FE numerical analysis embraced manufacture of the MLP pipe and test samples coupled with the reeling procedure. Sensitivity analysis on pipe strength and geometrical mismatch was performed to demonstrate the robustness of the linepipe material solution and reeling procedure.

All of the critical qualification activities were performed and verified by DNVGL and in accordance with the guidance of DNVGL-RP-A203 Technology Qualification process.

The paper highlights the qualification programme performed to enable the cost effective use of thin liner MLP, specifically Alloy 625, for risers installed by reel-lay.