bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized Multi-Release Framework for Fault Prediction in Open Source Software
Authors: Khurshid Shozab , Shrivastava A.K. , Iqbal Javaid
Published: August 2021

Software developing communities are shifting to open source software (OSS) because of the reason that software development takes place in successive releases, thereby improving its quality and reliability. Multi-release development of OSS can provide an opportunity to inculcate the dynamic needs of the user in a very short span of time to survive in the market. In spite of having these benefits, numerous challenges can be faced during the multi-release OSS development. Some of the challenges can be the generation of errors during the addition of new features. To address the changing fault detection process, a change point phenomenon is considered so as to give more practicality to the model. In this article, we present a general framework for multi-release OSS modelling incorporating imperfect debugging and change points. Parameter estimation and model validation is done on the three releases of Apache, an open source software project.
The Effects of ICT Adoption on Public Sector Performance
Authors: Alhassan Muftawu Dzang , Adam Ibrahim Osman , Musah Alhassan , Wahaga Esther
Published: August 2021

Governments around the world are increasingly adopting innovative ways that facilitate the easy provision of public sector services through efficient and effective ways. However, the linkages between ICT adoption, human resource (HR) quality, and public sector performance remains under-examined. This study examines the effects of ICT adoption and HR quality on public sector performance on one hand and the mediating effects of HR quality on the linkage between ICT adoption and public sector performance on the other using archival sources of data for 140 countries and a conceptual model based on the technology-organization-environment (TOE) framework. The data analysis using partial least squares-structural equation modeling shows that ICT adoption influences HR quality but not public sector performance directly. However, HR quality was found to positively influence public sector performance. Furthermore, HR quality was found to significantly moderate the relationship between ICT adoption and the public sector performance.
Risk Propagation Mechanism Research Based on SITR Model of Complex Supply Networks
Authors: Zhu Jianjun , Cheng Yamin , Zhang Yuhuai
Published: August 2021

Supply chain risk management is an important topic in supply chain management. The authors investigate the rules and characteristics of risk propagation in complex supply networks. Aiming at the characteristics of complex supply chain with complex structure and large risk consequences, considering the different impact capabilities and different anti-risk capabilities of each enterprise node, this paper proposes a SITR (susceptible-infected-temporarily removed-completely removed) risk propagation model based on weighted networks. After the dynamic analysis of the proposed model, numerical simulation is performed, and a supply chain risk control strategy is proposed according to the simulation results. The research shows that the enterprise's complete recovery rate and risk infection rate have a greater impact on the risk propagation in the supply chain network. Enterprises should increase their awareness of risk management and control, improve their complete recovery rate, and reduce their risk of infection.
Differences in Distance and Spatial Effects on Cross-Border E-Commerce and International Trade
Authors: Du Qunyang , Deng Danqing , Wood Jacob
Published: August 2021

Distance and space are important factors affecting international trade, but they have different effects on cross-border e-commerce (CBE) due to the creation of the Internet. This study utilizes spatial autocorrelation, the multi-dimension gravity model and the Spatial Durbin model to conduct an comparative analysis of international trade and CBE within one-belt one-road (BR) countries. Our study obtained several key findings. Firstly, the spatial autocorrelation effect which exists in international trade does not exist in CBE. Secondly, the geographical distance effect of CBE is not significant, which is different from that of international trade. Thirdly, CBE is affected by GDP, culture, policy and institution distances which is not entirely consistent with international trade. Finally, the Spatial Durbin model shows that the spillover effect of CBE and international trade are both significant in the inverse distance weight matrix. These findings provide not only important theoretical contributions but also a practical guide for Government policy makers of the BR and CBE.
Overall heritability in popcorn estimated by meta-analysis
Authors: Clóvis Luiz Rafael , Pinto Ronald José Barth , Uhdre Renan Santos , Rosa Jocimar Costa , Zeni Neto Hugo , Vivas Marcelo , Amaral Júnior Antônio  Teixeira do
Published: August 2021

The objective of this study was to conduct a meta-analysis and test its efficiency in summarizing the heterogeneous data of heritability estimates for the traits of grain yield (GY) and popping expansion (PE), and to provide reliable estimates of selection gains in popcorn. Therefore, 97 heritability estimates ( ) for popcorn GY and PE in the broad and narrow sense were used. The main procedures underlying the estimation of the combined heritability ( ) using the technique of meta-analysis consisted of i) an exploratory analysis of the set of heritability estimates to detect outliers using a box-plot chart, ii) the verification of the required statistical assumptions, iii) testing the involved heritability estimates for homogeneity, and iv) the calculation of the estimates of combined heritability. The meta-analysis facilitated the synthesis of the information pertaining to heritability in popcorn. The combined heritability estimates ( ) in the broad sense for GY and PE were 0.5208 ± 0.0229 and 0.6356 ± 0.0209, respectively, and in the narrow sense were 0.3290 ± 0.0292 and 0.3083 ± 0.0298, respectively.
As pessoas por trás dos números da Covid-19: argumentação nas capas d’ O Globo
Authors: Carmelino Ana Cristina
Published: August 2021

Este artigo busca refletir sobre uma das premissas gerais que são indispensáveis para quem pretende valer-se da persuasão no discurso, conhecida como lugares da pessoa. Esses lugares dão preferência à pessoa, que é ressaltada sobre as coisas. Para isso, tomam-se aqui para análise alguns discursos sobre a pandemia instaurada no mundo pelo coronavírus, a Covid-19. Como corpus de estudo deste artigo, em termos metodológicos, levam-se em conta duas capas do jornal O Globo, do Rio de Janeiro, especificamente as edições que registram quando o Brasil ultrapassou as 10 mil mortes (publicada em 10 de maio de 2020) e as 100 mil mortes (edição de 9 de agosto de 2020) pelo vírus. O objetivo é mostrar de que modo a valorização ao ser humano funciona, nos discursos sobre a Covid-19, como um argumento eficiente com forte apelo persuasivo, capaz de mover o auditório, suscitando ou realçando dignidade, mérito e respeito. A reflexão é fundamentada nos pressupostos da Retórica clássica (Aristóteles, 1983, 2011), campo no qual os lugares tiveram origem, e da Nova Retórica (Perelman & Olbrechts-Tyteca, 1996), especificamente no que diz respeito aos lugares da pessoa.
Experimental Analysis of Flat Slab Locally Supported by an Elongated Column
Authors: Šarvaicová Simona , Borzovič Viktor
Published: August 2021

The paper deals with the loading test results of an experimental reinforced concrete flat slab fragment, which was supported by an elongated rectangular column. The slab specimen was 200 mm thick and was without shear reinforcement. By experimentally obtained punching capacity, the accuracy of the standard design models for prediction punching resistance will be compared. The results of the experiment were also compared with the results of a numerical nonlinear analysis performed in the Atena program.
Effect of Struts and Stirrups Inclinations on Shear Resistance
Authors: Fillo Ľudovít , Halvonik Jaroslav
Published: August 2021

The subject of the article is the analysis of the design of concrete members for shear from the point of view of theory and code regulations. These give formulae for verification of shear resistance and recommended limits of individual parameters, respectively. The authors explain the relevant formulae using a Strut and Tie analogy, especially the effect of the inclination of struts and the inclination of stirrups on the shear capacity of beams as well as the effect of a single concentrated force acting at distance up to 2d from the edge of support.
Evaluation of Behaviour of Plan Curved Structure Supported by Arch
Authors: Trenz Jan , Zlatuška Karel , Necas Radim , Stráský Jiří
Published: August 2021

New type of plan curved structure has been developed within the research of arch footbridges at Faculty of Civil Engineering of Brno University of Technology. Structural arrangement came out of study of behaviour of plan curved upper deck arch structures of various radii of curvature. The design method of such structures with ideal shape of arch was the outcome of the research. Results of numerical analysis were verified on physical model in scale 1:10, which has been built and tested. The model has been mounted with gauges – 41 strain gauges at various positions on concrete and steel part of the structure and 5 deflection sensors. Then the structure has been subjected to loads in various positions corresponding with load positions of variable loads in calculation model. The paper describes evaluation of measurement of stresses and deformations of physical model of plan curved structure supported by an arch. Obtained values of stresses and deformations were compared with values derived from FE calculation model.
Construction-Technical Survey of the Interspace of an Industrial Chimney
Authors: Pešata Michal , Prochazka Lukáš , Bilek Vlastimil , Boháčová Jana
Published: August 2021

Chimneys are high-rise buildings indispensable for the operation of important plants in industry and in energy. The paper deals with the description and evaluation of defects found on reinforced concrete structures in the chimney interspace. The object of the inspection was a chimney with a reinforced concrete monolithic stem and an offset protective casing. The space between the housing and the stem is ventilated. During the operation of the chimney, aggressive condensate penetrates into the interspace, as a result of which unprotected reinforced concrete structures can degrade.
The Analysis of the Intensity and Vibration Time on the Mechanical Properties of Hardened Concrete
Authors: Trtík Tomáš , Chylík Roman , Fladr Josef , Vaskova Jitka
Published: August 2021

In order to achieve optimal physical and mechanical properties of hardened concrete, it is necessary to determine the right intensity and vibration time of fresh concrete during casting. Since concrete is considered as a polydisperse substance and various aggregate grains move randomly during vibration, it is very difficult to describe this stochastic phenomenon using exact physical equations and it is more advantageous to apply an experimental approach to verify the effects of vibration on fresh concrete. The effect of vibrations on fresh concrete increases the speed gradient of individual grains and thus reduces the viscosity of the cement paste. The intensity of vibration is determined mainly by the frequency, amplitude and centrifugal force of the eccentric of the vibrating machine. The optimal vibration time is generally considered to be the "minimum required". Insufficient vibration caused by an unsuitable vibrating machine or a short vibration time can result in insufficient compaction of the aggregate grains, non-release of accumulated air from the fresh concrete mixture, formation of cavities or poor-quality casting of parts of the structure with a higher degree of reinforcement. Vibration with excessive intensity or time can also be considered dangerous. The over-compaction of concrete is most often demonstrated by segregation of aggregates. The presented research deals with the determination of the optimal time and intensity of vibration of fresh concrete mixture to achieve the required physical properties of concrete, i.e. high compressive strength and modulus of elasticity of hardened concrete while reducing the negative effects of vibration, especially segregation of aggregates.
Effects of Concrete Compositions on the Elastic Modulus
Authors: Hela Rudolf , Bodnárová Lenka , Křížová Klára
Published: August 2021

The paper comments on the influence of various technological factors influencing the values of elastic modulus. Today, the composition of concrete combines the classic input components with the significant use of mixed cements, active admixtures and superplasticizers in order to achieve the required compressive strength of concrete and durability while reducing costs. On the other hand, the composition of these concretes has a negative impact on the elastic modulus which are significantly lower than the values derived from compressive strength in Eurocode 2. At the end of the article is a list of measures that are a prerequisite for obtaining the required concrete elastic modulus.
Properties of Spanish Broom Fiber Reinforced Concrete
Authors: Juradin Sandra , Boko Ivica , Netinger Grubeša Ivanka , Jozić Dražan , Mrakovčić Silvija , Vukojević Iva
Published: August 2021

Building materials based on renewable resources such as plant fibers are increasingly needed, especially if the plant is local and easily accessible. One such plant is the Spanish broom, a typical shrub of the Mediterranean region. In this work, Spanish broom fibers were used for the first time to reinforce concrete. Four mixtures were made: a reference mixture and three mixtures reinforced with 3 cm long fibers, in the amount of 0.5% of the total volume. Cement CEM I 42.5R, crushed limestone aggregate (D = 16 mm), and tap water were used for all the mixtures and in equal quantities. Four mortar mixtures were also made: standard mortar and 3 fiber-reinforced mortars. The mortar is reinforced with fibers of the same length and quantity as the concrete. The fibers were obtained by maceration of Spanish broom in solutions of 8%, 10%, and 15% NaOH. The quality and mechanical properties of the cellulose fibers depend on the geographical and climatic conditions and the fiber extraction procedures so the aim of this study was to evaluate the influence of different chemical pre-treatments of the fibers on the mechanical properties of the concrete. The properties of the fresh mix were determined using the flow method. Hardened concrete was tested for compressive and flexural strength and dynamic modulus of elasticity. Compressive and flexural strengths were determined on cement mortars. The results obtained on concrete were compared with those obtained on the mortar. It was concluded that the quality of composite materials is more influenced by the quality of the placement than by fiber treatment.
Use of Ash after Denitrification as an Additive to Concrete Based on Alcali-Activated Slag
Authors: Prochazka Lukáš , Boháčová Jana
Published: August 2021

This paper deals with the possibility of using fly ash after denitrification by the SNCR method a partial replacement in alkali-activated concrete based on blast furnace granulated slag. Previous research has verified the use of fly ash after denitrification in alkali-activated materials based on blast furnace granulated slag, and so far no negative effects on the properties of these mixtures have been found. The tests were performed on cement test specimens. As part of the preparation of concrete mixtures, two recipes were prepared. The first reference mixture contained only blast furnace granulated slag activated by sodium water glass with silicate modulus of 2. The second recipe was modified by replacing of 30% slag by fly ash after denitrification by SNCR method. Within the strength characteristics, the reference mixture always achieved better results. Very slow increases in strength were recorded for the mixture with 30% slag replacement by fly ash, when the compressive strength after 7 days of maturation was only 4.5 MPa.
The Influence of Various Types of Reinforcement of the Concrete Pillars of Precast Walls with an Opening
Authors: Šimek Ondřej , Zich Miloš , Janda Miloslav , Necas Radim
Published: August 2021

The subject of the article is a comparison of the precast reinforced concrete pillars with different types of reinforcement. These are the pillars simulating parts of walls that can, for example, form in the precast wall of residential buildings after an opening has been carved. The pillars are variously reinforced: from the simple reinforcement with wire mesh to the reinforcement with standard reinforcement bars. Behavior of the pillars, that have been subjected to two types of experiments in the past, is verified by software for non-linear analysis for concrete structures. Depending on the types of loading, the ultimate limit state, deformation and stress state of the individual pillars are studied.
Applications of Lithium-Ion Batteries in Offshore Oil & Gas: The Journey to Building a Low-Emissions Drilling Rig
Authors: Settemsdal Stig
Published: August 2021

This paper discusses applications for lithium-ion batteries in an offshore oil and gas environment and describes how battery packs/energy storage can be applied in hybrid, diesel-electric power plants to create low-emissions drilling rigs.

The incorporation of energy storage, particularly in direct current (DC) based power plants, can provide a wide range of benefits for operators, allowing them to reduce the runtime of onboard diesel engines and optimize combustion efficiency, thereby maximizing fuel utilization and reducing emissions. Batteries can also be used to create new redundancy schemes, as well as for peak shaving and blackout prevention.

The West Mira semisubmersible installation in the North Sea was the world's first modern drilling rig to operate a low-emission hybrid (diesel-electric) power plant with lithium-ion batteries connected to the main power grid. The paper describes the energy storage solution that was implemented on the facility and discusses how considerations for safety and reliability were addressed.
Reimagine LNG – An Overview of the LNG Market Potentially Leading to a Future AFLOAT
Authors: Subramanian Aparna
Published: August 2021

Objective / Scope

LNG has proven its worth, to meet energy demands throughout the globe at scale, whilst providing the cleanest fossil fuel. To complement the emerging trend of energy transition all over the globe, LNG provides a robust solution for a potential future.

This paper will describe the current state and outlook of the LNG market, rethinking of LNG contracts and the major drivers that could favor a Floating LNG facility as a market driver compared to land-based facilities.

Methods, Procedures, Process

With recent events which include the oil price slump, LNG supply glut and the ongoing COVID 19 pandemic, the imbalance in the LNG market is predicted to run with low market price that could last up to four more years.

On one hand, low market price is putting a lot of pressure on suppliers but on the flip side, this can be a game changer for the consumers. Consumers can potentially exploit buyers' market by making the investments much stronger to strive towards a clean future.

Conventionally LNG producers have been land-based until facilities like Golar LNG made historical success. The focus of the Floating LNG industry is now directed towards small and mid-scale production.

With a constant demand from stakeholders to get facilities up and running in a short development schedule, Floating LNG can provide some compelling benefits when combined with the concept of an economic time chartering investment rather than a CAPEX investment. This leads to a shortened execution time from discovery to market and avoids the extensive and time-consuming permitting and land use issues that are typical of onshore projects.

The main drivers / challenges for a Floating LNG Facility investment are

· Location, associated country regulatory restrictions · Source of gas · Market demand · Technology based on capacity · Project financing

Floating LNG can not only provide economic benefits for first use but could also provide a commercial route to easy re-deployment to new gas sources, wherever necessary and possible.

The paper will include:

· Reflection on the LNG market of the recent past · Impact of COVID 19 on LNG market globally and the projected trends by various analysts · Overview of LNG contract types · Technical and commercial Drivers of Floating LNG which will potentially influence the market

Results, Observations, Conclusions

The take-away from this paper is a deeper understanding of the following:

· Current LNG market and outlook · Reimagine LNG Contracts · Re-explore Floating LNG drivers

Novel / Additive Information

While the COVID 19 has created one of the reasons for the major impact on the market, this paper will present more interesting facts on many other contributing reasons for the present market downturn.

This will in turn give an in-depth understanding for reimagining the major three drivers of Floating LNG, potentially leading to a WIN-WIN solution. This will help to sustain a constant cash flow amongst both sellers and buyers.
Towards Remote Inspections of FPSO's Using Drones Instrumented with Computer Vision and Hyperspectral Imaging
Authors: Stensrud Erik , Torstensen Are , Lillestøl Dag-Børre , Klausen Kristian
Published: August 2021

The Class Society DNV has performed production surveys in enclosed spaces using drones since 2016, demonstrating cost savings and increased personnel safety. The goal is to develop autonomous inspection drones to reduce the need to enter tanks and enable remote inspection. The vision is a drone that can fly by itself, track where it is, and spot rust and cracks, and measure steel thickness. We expect that drone-assisted remote inspection will reduce survey costs for the clients and be a major safety improvement for surveyors. Several drone capabilities are required to enable visual close-up inspection and non-destructive testing in enclosed, GPS-denied, and poorly lit environments. In this study, we report the most recent status from an ongoing research project, including several industry partners. We highlight technical challenges and preliminary results on drone navigation functionalities, computer vision for detection of cracks, and the use of hyperspectral imaging to detect and classify the chemical composition of coatings, rust, and other use cases.
Are You in the Green? The Economic Impact of Carbon-Conscious Choices on Project Development Planning
Authors: Choe David Sung , Whitworth J. Lynne , Kak Ashutosh , Bisset Genevieve
Published: August 2021

The greenhouse-gas (GHG) emissions target set by UNFCCC Paris Accord in 2016 will emerge as a new value driver to project development planning that has the potential to degrade the viability of future offshore oil and gas projects. Integration of GHG emissions and legislated carbon price as new decision drivers to project decision-making will require an in-depth understanding on the overall economic impact of carbon-conscious choices. In this light, the purpose of this paper is to present the impact of such choices on project development planning and implications for Decision Quality (DQ).

The case study presents a comparative assessment of total GHG emissions and comparative project economics for a Greenfield project, considering four development concepts: a Reference Case with a "traditional" offshore facility and three hypothetical cases, each of which are defined, evaluated, and compared against the Reference Case. Development of each case is discussed and created to support decision-making during project development planning. The paper presents an economic comparison to demonstrate the importance of including a carbon assessment early in project development planning to assure a thorough concept evaluation. It also demonstrates how a clear outlook on the annual GHG intensity over project life can be vital, for project sanction and mitigation of high carbon cost penalties in the future regulatory landscape.

Early understanding of risks associated with carbon price and regulatory enforcement can potentially change how industries analyze the viability of their projects/assets. The paper demonstrates the importance of assessing carbon-conscious options early in the project development planning stage, and how this helps developers to navigate the risks and opportunities in the drive to a lower-carbon society.
Qualification and In-Service Performance of an Additively Manufactured Oilfield Pump Impeller
Authors: Rettew Robert , Griffiths David , Rettberg Robin
Published: August 2021

This article will outline the development, qualification, and in-field service trial of an additively manufactured 316 stainless steel pump impeller in chloride-containing water service for approximately 9 months. The pump impeller was manufactured by a hybrid directed energy deposition (DED) process. The novel process combines 5-axis DED and machining in one setup which brings significant reductions in lead time and other flexibility when compared to conventional manufacturing methods. Further benefits and challenges will be outlined. Qualification test results including mechanical properties, corrosion resistance, and select micrographs of the material will be shown. A post-service analysis of the performance of the component is also provided. Discussion of the applicability of 3D printing to end users, creating value in rapid component delivery and innovation, is included. A forward-looking assessment of the next steps for impeller design and manufacturing with additive manufacturing is also included.
A System-Theoretic Approach to Well Control Assurance Programs
Authors: Baylor Brandon Scott
Published: August 2021

The world's leading energy companies face new challenges as they aggressively pursue digital innovation and acceleration. Oil and gas well construction, in particular, will continue to incorporate automation to enhance capabilities and provide a competitive advantage. These changes to the technology landscape will fundamentally alter the nature of well construction and the interactions pertaining to well design, operation, and maintenance.

One key element of well construction is process safety. To prevent incidents, well control assurance programs are created to ensure subsurface hazards are mitigated and controlled. However, to continuously adapt and keep pace with ongoing digital transformation, assurance programs must be continuously revisited to improve in the face of a changing environment. One way to do this is by using systems engineering principles, methods, and tools. System-Theoretic Accident Models and Processes (STAMP) and System-Theoretic Process Analysis (STPA) developed by MIT's Nancy Leveson can help assess assurance programs and uncover opportunities to improve.

This paper analyzes oil and gas assurance programs and generates system requirements based on causal factors that impact the efficacy of the assurance program as a whole. This, in turn, helps identify safe system boundaries and constraints to be enforced to achieve system safety. This paper demonstrates the value of STPA as an integrated analysis method and offers specific recommendations to improve oil and gas assurance processes.
Effect of Fins on Combined Loaded Suction Caisson in Deepwater Clay Soils. A Numerical Analysis
Authors: Castillo Garcia Pablo , Panayides Stylianos
Published: August 2021

Suction piles are a form of foundation widely adopted in the offshore energy industry. Efforts to enhance the combined Vertical-Horizontal (V-H) performance of piles with the addition of fins, attracted interest from the engineering community in the beginning of the 21st century. Design of this enhancement was surfaced whilst examining foundation solutions for renewable energy projects. Studies to date have primarly considered relatively shallow waters comprising sandy soils, with the behaviour of fin-enhanced piles in very soft to soft clay soils, receiving less attention. The present study emphasis is on typical deep-water deposits of soft clay and attempts to evaluate the impact of varying fin length, shape, orientation and location, on the combined capacity of suction piles by means of three-dimensional finite element analyses. The paper investigates two types of load configuration; in the first instance loading at the pile head and secondly with the load attachment point located at approximately two thirds of the pile embedded length. These two configurations cover different foundation solutions, such as support for subsea infrastructure and anchoring for floating facilities, respectively. Optimum fin-enhanced suction pile configurations are presented for each application, with the results from this study indicating an increase of the load-carrying capacity in V-H space, whilst reducing the overall suction pile size. The efficiency of various configurations is presented with composite plots of increase in holding capacity, plotted against the increase in steel surface area. Preliminary recommendations on fin length, location, shape and orientation for typical suction pile applications are presented with intent to demonstrate the potential for cost savings and reduction in both operational and schedule risk.
Acquire Ocean Bottom Seismic Data and Time-Lapse Geochemistry Data Simultaneously to Identify Compartmentalization and Map Hydrocarbon Movement
Authors: Schrynemeeckers Rick
Published: August 2021

Current offshore hydrocarbon detection methods employ vessels to collect cores along transects over structures defined by seismic imaging which are then analyzed by standard geochemical methods. Due to the cost of core collection, the sample density over these structures is often insufficient to map hydrocarbon accumulation boundaries.

Traditional offshore geochemical methods cannot define reservoir sweet spots (i.e. areas of enhanced porosity, pressure, or net pay thickness) or measure light oil or gas condensate in the C7 – C15 carbon range. Thus, conventional geochemical methods are limited in their ability to help optimize offshore field development production.

The capability to attach ultrasensitive geochemical modules to Ocean Bottom Seismic (OBS) nodes provides a new capability to the industry which allows these modules to be deployed in very dense grid patterns that provide extensive coverage both on structure and off structure. Thus, both high resolution seismic data and high-resolution hydrocarbon data can be captured simultaneously.

Field trials were performed in offshore Ghana. The trial was not intended to duplicate normal field operations, but rather provide a pilot study to assess the viability of passive hydrocarbon modules to function properly in real world conditions in deep waters at elevated pressures. Water depth for the pilot survey ranged from 1500 – 1700 meters.

Positive thermogenic signatures were detected in the Gabon samples. A baseline (i.e. non-thermogenic) signature was also detected. The results indicated the positive signatures were thermogenic and could easily be differentiated from baseline or non-thermogenic signatures.

The ability to deploy geochemical modules with OBS nodes for reoccurring surveys in repetitive locations provides the ability to map the movement of hydrocarbons over time as well as discern depletion affects (i.e. time lapse geochemistry). The combined technologies will also be able to:

Identify compartmentalization, maximize production and profitability by mapping reservoir sweet spots (i.e. areas of higher porosity, pressure, & hydrocarbon richness), rank prospects, reduce risk by identifying poor prospectivity areas, accurately map hydrocarbon charge in pre-salt sequences, augment seismic data in highly thrusted and faulted areas.
Fit For Service Qualification for Sour Service High Strength Production Casing For High Temperature
Authors: Lima Luciana I. L , Gomes Christelle , Landier Carine , Lima Marilia , Schleiss Kevin , Lazaro André F. , Diehl Bruno , Palmieri Ilson
Published: August 2021

In recent years the application of high strength carbon steel with 125ksi specified minimum yield strength as a production casing in deepwater and high-pressure reservoirs has increased. Sulfide stress cracking (SSC) can develop when high strength carbon steel is exposed to a sour environment. The H2S partial pressure in these sour reservoirs is above the 0.03 bar limit for this material at room temperature. Materials SSC performance evaluation requires an accurate simulation of field conditions in the laboratory. To evaluate the production casing SSC behavior, some fit for service (FFS) tests were carried out considering the well geothermic temperature profile for the materials selection.

This paper presents a fit for service qualification carried out on Casing 125 ksi SMYS (Specified Minimum Yield Strength) materials. Two products with 125ksi SMYS were considered: one that has existed for several years and one developed more recently with a better SSC resistance – above the pH2S limit considered for the standard 125ksi SMYS material. The results obtained in this test program allowed casing 125 ksi SMYS materials selection for temperature above 65°C and environment more severe in terms of pH2S than the domain previously established for this grade. This allowed a new well production design, which saves one casing phase and avoids the necessity to use intermediate liners to prevent collapse.
Water Injection Pipeline Repair Offshore Angola Enhances Production
Authors: Sobolewski Kamil
Published: August 2021

An international operating company detected a leak during an annual ROV inspection of a water injection (WI) pipeline offshore Angola in the Gulf of Guinea. The pipeline owner made the decision to repair the damaged line using clamps, but there were multiple challenges involved in executing the repair. First was the depth of the pipeline, which was on the seabed across an area that ranged from 1,170 m to 1,410 m (3,839 ft – 4,626 ft). Additional challenges included potential complications for clamp installation because of the location of the pipe welds and the physical condition of the pipe, which had experienced considerable wall thinning in multiple areas. Bringing the pipeline back into safe service required repairs to the aging pipe within a scope of work that included site preparation, the installation of two 12-in clamp connectors, and inspection services following clamp placement to verify proper installation.

Because there were welds in the WI pipeline, there was a risk that the clamp installation site would correspond with an area of the pipe that was welded, which would impact the ability of the clamps to fit snugly over the damaged area. Survey data were cross-referenced with the client's data to determine that the weld locations would not interfere with the installation. Coating removal was critical, so a purpose-built mechanical tool was designed to prepare the pipeline for clamp installation. The project also required finite element analysis (FEA) to confirm that the pipeline could withstand the seal load applied by the repair clamps.

The project was carried out in three steps. The objective of the first step was to prepare and stabilize the seabed to ensure it could bear the weight of the clamp installation frame and the impact of the ROV working nearby. The second phase focused on preparing the repair locations for installation of the clamps, a process that included coating removal and surface cleaning to return the WI pipeline to bare metal finish in the clamp areas. The third phase was the preparation and installation of the 12-in repair clamps. This included the inspection and spot cleaning of pipeline surfaces, clamp installation, and clamp seal verification.

The two clamps were successfully installed and passed pressure testing in February 2020, enabling the operator to bring the WI line back online and functioning safely at reduced pressure.

This repair employed the highest-pressure clamp of this type installed to date (138 bar / 2,000 psi).
First Use of ROV Remote Operations from Shore in the Gulf of Mexico
Authors: Silva Simao , Terrell Blake , Philip Mark , Rouge Nicholas , Angelidis Diogenes , Sosa Julio , Collins Robert , Rauf Zain
Published: August 2021

Oil and gas companies across the spectrum are moving toward digitalization. Leveraging technology to access real-time data has allowed companies to streamline activities and gain operational efficiencies while at the same time improving worker safety by reducing the number of personnel required offshore. This evolution optimizes operations by enabling better decision-making by subject matter experts (SMEs) located around the world working as one interconnected team. Functions once performed exclusively by offshore personnel are being carried out today by onshore workers via remote technology. By capitalizing on the ability to communicate offshore via high-speed internet, it is now possible to carry out ROV operations using a team that includes onshore based personnel.

A recent project illustrates how ROV activities controlled from an onshore remote operations center in Louisiana were carried out successfully on a production Tension Leg Platform (TLP) in the Gulf of Mexico (GoM).

The technology used onboard the TLP is not new; operators have been remotely managing a range of functions on offshore assets for years. However, the project does apply this proven approach to ROV piloting operations for the first time commercially in the GoM.

Transferring ROV control from the offshore platform to a facility onshore is possible using a communication link that connect real-time data from the offshore asset to the onshore remote operations center (OROC). The two-way communications link provides a redundant system in which controls can be executed either from the offshore platform or from the remote operations center, allowing specialized roles that historically have been executed offshore, including that of the ROV pilot, subsea engineer, and company representative directing the work, to be transferred to a land-based team. The increase in data required from the offshore asset for the GoM project was managed via a dedicated link that provided data transfer at a minimum speed of 3 Mbps upload/download with a fail-safe system that automatically default control to the offshore ROV team in case of any failures in the communication link.

Remotely piloting an ROV from shore and coordinating with an offshore crew not only delivered a reduction in HSE exposure but reduced overall personnel costs on the asset by more than 30% for 24 hours of operations. This approach to ROV operations has the potential to reduce costs by reducing the number of workers required offshore even further if additional staff associated exclusively with the project subsea work scope is directed to work remotely from shore.
Machine Learning-Based Optimization for Subsea Pipeline Route Design
Authors: Bhowmik Subrata
Published: August 2021

Optimal route selection for the subsea pipeline is a critical task for the pipeline design process, and the route selected can significantly affect the overall project cost. Therefore, it is necessary to design the routes to be economical and safe. On-bottom stability (OBS) and fixed obstacles like existing crossings and free spans are the main factors that affect the route selection. This article proposes a novel hybrid optimization method based on a typical Machine Learning algorithm for designing an optimal pipeline route. The proposed optimal route design is compared with one of the popular multi-objective optimization method named Genetic Algorithm (GA).

The proposed pipeline route selection method uses a Reinforcement Learning (RL) algorithm, a particular type of machine learning method to train a pipeline system that would optimize the route selection of subsea pipelines. The route optimization tool evaluates each possible route by incorporating Onbottom stability criteria based on DNVGL-ST-109 standard and other constraints such as the minimum pipeline route length, static obstacles, pipeline crossings, and free-span section length. The cost function in the optimization method simultaneously handles the minimization of length and cost of mitigating procedures. Genetic Algorithm, a well established optimization method, has been used as a reference to compare the optimal route with the result from the proposed Reinforcement Learning based optimization method.

Three different case studies are performed for finding the optimal route selection using the Reinforcement Learning (RL) approach considering the OBS criteria into its cost function and compared with the Genetic Algorithm (GA). The RL method saves upto 20% pipeline length for a complex problem with 15 crossings and 31 free spans. The RL optimization method provides the optimal routes, considering different aspects of the design and the costs associated with the various factors to stabilize a pipeline (mattress, trenching, burying, concrete coating, or even employing a more massive pipe with additional steel wall thickness). OBS criteria significantly influence the best route, indicating that the tool can reduce the pipeline's design time and minimize installation and operational costs of the pipeline.

Conventionally the pipeline route optimization is performed by a manual process where the minimum roule length and static obstacles are considered to find an optimum route. The engineering is then performed to fulfill the criteria of this route, and this approach may not lead to an optimized engineering cost. The proposed Reinforced Learning method for route optimization is a mixed type, faster, and cost-efficient approach. It significantly minimizes the pipeline's installation and operational costs up to 20% of the conventional route selection process.
Feasible SCR Configuration from FPSO with Large Motions, by Applying Residual Curvature Methods
Authors: Ramiro Andre Amorim , Orimolade Adekunle Peter , Karunakaran Daniel Nalliah
Published: August 2021

This paper describes an alternative and innovative solution to Steel Lazy Wave Risers (SLWR) in order to allow the rigid riser be designed in a free hanging configuration from a floater with large hang off vertical motions.

This work demonstrates that the residual curvature method can reduce the stress at the touchdown zone (TDZ) within acceptable limits and improves fatigue life when compared to a Steel Catenary Rigid (SCR).

The state-of-art concept eliminates the necessity of buoys in a SLWR concept. Further, there will be saving in installation time, this combined reduces the CAPEX to develop new projects, making it a very attractive solution in recent market scenario.

The results for Brazil offshore scenario at Santos Basin and in Gulf of Mexico, in a water depth of 2100m indicate a considerable reduction on the stress at the TDZ within acceptable limits.

Fatigue results indicate a slight improvement when compared to a SCR in a free hanging configuration. The fatigue performance for the Gulf of Mexico condition has sufficient fatigue life. However, it has potential margin to be developed in the future and achieve better results.

The new concept was evaluated numerically through a comprehensive load case matrix contemplating extreme and fatigue analysis. Results indicated the feasibility of the solution, making it a considerable alternative to replace SLWR in harsh environments.
Mitigating Wellhead Fatigue While Reducing HSE Risk, Deck Spread, Deployment Time, and Crew Size
Authors: Ulland Gunnar , Hilsen Gunnar , Croatto Stefano
Published: August 2021

Subsea wellhead systems have a design fatigue life that is expected to withstand the damage incurred from stress caused by cyclic loading during its operation. Wellhead fatigue is a critical factor when drilling offshore wells because the condition of the wellhead determines the length of time drilling activities can be carried out safely.

The presence of the BOP on top of the wellhead affects fatigue life. Initially, these units were designed for 6-in. and 10-in. diameter casing and weighed slightly less than 1,400 lb. [ASME, 2003) Over time, BOPs evolved, and today's units are considerably larger and heavier than their predecessors, weighing in at approximately 400 metric tons. This increase in size and weight on the wellhead negatively impacts fatigue life.

In recent years, the oil and gas industry has begun to look for ways to reduce wellhead fatigue to extend the life of the wellhead and expand the margins for safe drilling operations. A new ROV-operated Wellhead Load Relief (WLR) system, developed specifically to mitigate fatigue, uses special tensioners that are tethered individually to the BOP. Each tensioner contains a hydraulic spooling unit with a lock- and-pull mechanism that allows the ROV to tighten adjustable tethers subsea, pulling them from slack to a maximum tension of 35 metric tons.

This approach to installation is a departure from common industry practice, which necessitates the configuration of the predetermined tether lengths on the topside. The ROV-operated WLR system described in this paper is a compact, high-capacity BOP tethering system suitable for both template and seabed anchoring. It provides a new and efficient way of tethering the BOP to avoid wellhead fatigue and delivers additional benefits that include minimized HSE risk, a smaller deck spread, decreased deployment time, and a smaller crew.

The WLR system was operated subsea for the first time in December 2019. By precisely tensioning each tether and limiting the load transferred to the wellhead, the WLR significantly lessened wellhead fatigue, resulting in an almost complete halt in BOP movement.

This new technology enables the operator to make optimal use of the fatigue life of the wellhead without compromising efficiency or safety.
Subsurface Characterization Using Ensemble Machine Learning
Authors: Leiceaga Gorka G , Balch Robert , El-kaseeh George
Published: August 2021

Reservoir characterization is an ambitious challenge that aims to predict variations within the subsurface using fit-for-purpose information that follows physical and geological sense. To properly achieve subsurface characterization, artificial intelligence (AI) algorithms may be used. Machine learning, a subset of AI, is a data-driven approach that has exploded in popularity during the past decades in industries such as healthcare, banking and finance, cryptocurrency, data security, and e-commerce. An advantage of machine learning methods is that they can be implemented to produce results without the need to have first established a complete theoretical scientific model for a problem – with a set of complex model equations to be solved analytically or numerically. The principal challenge of machine learning lies in attaining enough training information, which is essential in obtaining an adequate model that allows for a prediction with a high level of accuracy. Ensemble machine learning in reservoir characterization studies is a candidate to reduce subsurface uncertainty by integrating seismic and well data. In this article, a bootstrap aggregating algorithm is evaluated to determine its potential as a subsurface discriminator. The algorithm fits decision trees on various sub-samples of a dataset and uses averaging to improve the accuracy of the prediction without over-fitting. The gamma ray results from our test dataset show a high correlation with the measured logs, giving confidence in our workflow applied to subsurface characterization.