Table of contents

November 27 – 29, 2019, University of Stavanger, Norway

Preface

This conference is organized as a joint event of the COTech (Computational Methods in Offshore Technology) and OGTech (Oil and Gas Technology) conferences. The COTech conference started as part of the research and dissemination activities of the Program Area for research "COTech - Computational methods in Offshore Technology" at Faculty of Science and Technology, University of Stavanger (UiS). This Program Area for Research was founded in 2015 with seven professor, four associate professors, two adjunct professors and five research (PhD) students from the Department of Mechanical and Structural Engineering and Materials Science (IMBM), whose expertise and competence lies primarily within use of computational methods such as finite element methods, boundary and volume element methods, computational fluid dynamics and the like in marine and subsea technology, marine operations, design and analysis of mechanical systems, integrity and reliability of offshore structures and mechanical systems, renewable energy and wind engineering. In the offshore-related engineering area in particular, numerical computation approach is nowadays not only serving as a means to cultivate and realize innovative ideas, but also it is becoming the primary choice to solve complex engineering problems for the harsh and unfriendly environment in the Arctic.

The OGTech conference is organized as part of a collaborative project called UTFORSK between a team of researchers from University of Stavanger and Gubkin Russian University of Oil and Gas. The overall aim of the project is to make the team stronger and more sustainable. Among others, the project focuses on building a bridge of collaboration in research and education between the two countries, Norway and Russia, that share the Arctic region and to strengthen the research aspects of the Offshore Technology field in Arctic environment. By facilitating mobility of researchers and staff in both directions, the project aims to provide a common and successful learning environment for young researchers (Masters and PhDs) to make sure that students have skills and knowledge required in order to face the challenges that the Offshore industry meets in the North - such as environmental aspects and Offshore Technology within subsea/marine structures in cold climate.

List of Conference Organizing Committee, Topic Area Coordinators, Invited Keynote Speakers, Technical Committee Members and Reviewers are available in the pdf

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

In this study, computational fluid dynamics has been applied to analyze the performance of both structured and unstructured meshes when used in steady-state simulations of wind in an urban area. This case specifically examines the wind environment around a single high-rise building with the geometry of 1: 1: 2 (length, width, height) within the atmospheric boundary layer.The Reynolds-averaged Navier-Stokes simulations were conducted using OpenFOAM, with grids generated with blockMesh, snappyHexMesh, and Pointwise. A set of coarse meshes and a set of fine meshes were used for comparison.Minor differences in the flow pattern were observed depending on the mesh type used, including the reattachment lengths, the drag coefficients, the velocity profiles, and the positioning of the vortex leeward of the high-rise building. However, the main flow features were the same, indicating that for simulations where overall flow features are of importance there is high flexibility in choice of meshing technique.

In recent years, interest in exploiting wind power in deep waters has grown, with the realization of floating structures that could accommodate a turbine and produce electricity. One of the many challenges that these projects face is the position keeping of the system in a defined part of the sea: this is carried out with mooring systems, designed to withstand extreme marine conditions. The first aim of this work is to analyze these systems, to find a general solution for a floating wind farm in the Italian seas. Of importance is to suggest a design that could be fabricated in an Italian dry dock and towed to site. A numerical model of the floating structure and the environment has been realized using the software, OrcaFlex, and simulating the 50- and 100-year return period conditions in the Adriatic Sea and in the Strait of Sicily, with different mooring combinations of present-day technologies. The model's implementation requires environmental and structural parameters: the former have been obtained with a statistical analysis of actual recordings of wind speed and wave height and with the official Italian cartography. Structural details have been derived by looking at existing floaters, finding the most suitable one for the Italian environment. After simulations, the results are interpreted with a comparison of tension in the lines, vertical forces at the anchors, wire length and mooring footprint, finding out that depth has the greatest impact on these factors. With respect to this, the proposed numerical model can provide a simple indication for the mooring of floating wind turbines in two different areas of the seas surrounding the Italian peninsula: for the Adriatic Sea (shallow waters), suction anchors with chains should be preferred, while, for the Strait of Sicily (deeper waters), traditional anchors may be considered, with lines composed of chains or a combination of chains with synthetic fibers.

Aerodynamic response of a single-box suspension bridge girder is investigated using CFD simulations. The importance of including railings and vortex mitigating devices such as guide vanes and a spoiler in the simulations is explored since they alter the flow field around the deck greatly. The paper compares results from a bare deck section and a section with mitigating devices. A clear vortex shedding observed for the bare deck section is suppressed by the use of mitigating devices and the aerodynamic force coefficients are very different between these cases. The effect of varying deck width is also studied. Flutter derivatives are defined based on quasi-steady formulation and flutter velocity is computed for each section. The section with the largest width to depth ratio has the best performance against flutter. This study is an initial phase of multi-fidelity optimization of bridge deck shape considering aerodynamic constraints.

Transport and installation of offshore wind turbines require considerable efforts and can be time consuming, in particular when jackups are used for lifting operations. This is mainly due to the specific weather window requirements for towing and locating the jackups. A goal is ultimately to finalize all turbine assembly work onshore and at quayside and to transport the completed turbine to the site for easy installation. We suggest that this can be achieved by a transport and installation method we denote "the MINT method" whereby the wind turbine foundation is located on a barge while the tower is resting on a support system, a "MINT" system that is located at the stern of a mid-size standard offshore support vessel. The MINT is specifically designed for the transport and installation operations allowing relative motions and rotations between the tower and the transport vessel. In order to qualify the "MINT installation method", a numerical study of the feasibility of the transport and installation was carried out by Sintef Ocean using their SIMO software package [1]. The method was found feasible in favourable weather conditions. To further document feasibility, it was decided to carry out a proof of concept test in a wave tank to identify concerns with respect to the suggested method for transport and installation. This paper reports the findings of this test. The test is to be considered to represent an initial activity in the concept qualification process, see [2], and is not a full wave tank test carried out to measure stresses and strains for member sizing. The objective of the paper is therefore, to show how an initial wave tank test can be useful for concept qualification.

Floating offshore wind turbines (FOWT) are exposed to harsh environmental conditions and often experience unstable atmospheric conditions. Including the effects of atmospheric stability should improve the accuracy of fatigue load calculations, and subsequently, the design of the wind turbine. The current standards recommend two turbulence spectral models that are valid for neutral atmospheric conditions only. The objective of this study is to investigate the influence of Hejstrup's 1981 Unstable Spectra Model on the loads and motions on a spar and a semi-submersible FOWT. This study focuses on the effect of unstable atmospheric conditions in the free stream wind and does not include the effect of wakes. The most significant differences observed in this study were for the tower top torsion loads, where very unstable conditions gave 47% larger loads than neutral conditions for OC3-Hywind turbine and 30.4% larger for OC4-DeepCwind turbine. Since very unstable conditions corresponded to the highest turbulence intensities and larger turbulent fluctuations, they also resulted in higher fatigue loads. The blade root flap-wise loads were also observed to be higher under unstable conditions compared to neutral conditions, but the differences were smaller with 7.5% for OC3-Hywind and 23% for OC4-DeepCwind.

The article presents an analytical method that can be applied to provide first estimates of wave runup (RU) and wave rundown (RD) on shorelines and coastal structures based on observed long-term wave statistics and is supplementary to [12] who based their results on long-term wind statistics. Some recently published wave RU and wave RD formulae are used, together with joint statistics of significant wave height and spectral peak period from the Northern North Sea. Results are exemplified for the average statistical properties of wave RU and wave RD in terms of the expected values and the standard deviations, as well as values estimated from 1-, 10- and 100-years return period contour lines.

The drag crisis is an interesting physical phenomenon for flow over bluff bodies, where the drag coefficient suddenly drops as the Reynolds number increases. This behavior is caused by the flow transitioning from laminar to turbulent flow in the boundary layer. The turbulent flow remains attached to the surface longer than the laminar flow, thereby reducing the size of the wake behind the body. The phenomenon has been extensively studied experimentally for simple geometries such as flow over a sphere or a cylinder. Numerical simulations, however, have mainly been performed in either the subcritical or the supercritical region. In this study, we investigate the ability of steady-state RANS CFD models to predict the drag crisis for flow around a sphere. Experiments using oil-film visualization are performed to determine the type of transition for flow over a sphere. Simulations are performed using OpenFOAM, with the k-ω shear stress transport (SST) turbulence model. For transition modelling, the Langtry-Menter modification to the SST model is considered. The simulations show improved prediction of the drag coefficient in the subcritical regime, but the implementation of the model is found to be unstable in the critical and supercritical range.

This paper provides numerical investigations of flow in a steady lid-driven cavity of depth to width ratio 1/3 containing a circular cylinder. The inner cylinder is treated using a direct-forcing immersed boundary method, and a project method is applied to solve the incompressible Navier-Stokes equations. Three different Reynolds numbers and positions of the cylinder are considered; for a lower Reynolds number, flow structures are weakly affected by the cylinder near the left wall while two clockwise vortices attached to the cylinder are formed as the cylinder moves rightwards; for a moderate Reynolds number, an anticlockwise bottom vortex is formed for the cylinder near the left wall, and it disappears as the cylinder is shifted rightwards; for the largest Reynolds number, two anti-clockwise vortices attached the cylinder are formed for the cylinder close to the left wall, and as the cylinder moves gradually closer to the left wall a bottom vortex is formed and disappears together with the clockwise vortex to the right side of the cylinder.

Energy efficiency of road vehicles is highly attributed to its aerodynamic performance. Over the last decades, significant reduction of aerodynamic drag has been made. But, beyond the current achievement, further improvement become a challenge for car industries and professionals working in the area. This paper focuses on new approach to further find aerodynamic performance improvement particularly for electric vehicles. Therefore, a preliminary numerical study on ducting and concept of energy harvesting from aerodynamic resistance is introduced as an alternative to improve energy efficiency. Ducted and slightly modified Ahmed model is used to study aerodynamic characteristics of ducted models and how ducting would contribute to the reduction of energy consumption due to air resistance. Three-dimensional, incompressible, and steady flow governing equations are solved by CFD code (PHOENICS ver.2018) with extended turbulent model proposed by Chen-Kim (1987). From the study, it is found that the total drag reduction of over 15% on the ducted models compared to the base model. The kinetic energy preserved due to ducting is also significant. Harvesting this energy and utilizing it to extend driving range is believed to be a potential area to be dealt in detail. Therefore, the idea of duct application and energy harvesting introduced in this paper, either to reduce or use aerodynamic resistance is expected to have potential contribution to the development of future energy efficient road vehicles.

The unsteady flows around two stationary rectangular cylinders with a chord-to-thickness ratio of B/D = 5 at Re_D = 2 × 10⁵ (based on the free stream velocity and the width length D), are investigated using two-dimensional Unsteady Reynolds-Averaged Navier-Stokes equations with a standard k − ω SST turbulence model. The computational model is validated by carrying out simulation of the flow around a single rectangle and comparing the hydrodynamic quantities (time-averaged drag coefficient, root-mean-square of fluctuating lift coefficient) with the previous published data. The aim of the present study is to study the influence of the relative positions between the two rectangular cylinders on their hydrodynamic quantities and the surrounding flow fields.

In the construction designing of oil field surface facilities, exists a problem of the seabed production equipment optimal placement. As an initial approximation, we can represent this task in the form of the linear Boolean programming problem. An application of routine methods of discrete programming can theoretically give the desired solution. However, these methods do not take into account the specific nature of the problem. This problem belongs to the NP class. So we can run into significant computational difficulties. This situation is typical for construction of the ground surface or subsea located facilities for real oil/gas fields. To overcome it, we propose to replace a discrete programming model with a linear programming one, which takes into account problem-specific properties. Also, we present examples of the application of the proposed parallel optimization algorithms. Input data for them: the seabed profile, geometry, and space distribution of oil/gas reserves. Optimization problem objective function is the penalty for the irrational placement of seabed production equipment elements.

Topology Optimization (TO) is a technique that allows for increasingly efficient designs and its objective is to maximize the performance of mechanical systems or structure in a variety of fields. Attempts to employ TO for parts manufactured with conventional methods such as casting, forging, injection moulding, CNC machining and the like could not lead to desired optimum results due to the existing manufacturing constraints regarding geometrical complexity. Currently, additive manufacturing (AM) techniques allow the fabrication of more complex shapes which in principle will lead to improved performances through application of the TO concept. This study focuses on structural optimization of additive manufactured parts of thermoplastic parts based on analysis of the stiffness/weight (mass) ratio for a beam subjected to a three-point bending load. The experimental work is done on optimization of parts manufactured by Fused Deposition Modelling (FDM) technology and finally compared with an identical model manufactured using Polyjet 3D printer. Different TO software are compared to conduct the optimization, and a module of SolidWorks 2018 from Dassault Systems is chosen for the topology optimization for the final experiment. The study focuses on the results on stiffness/mass ratios, paying attention to the influence of different printing parameters on the test results. An increase of stiffness/weight ratio of 31.7% was predicted by software while experiments showed an increase of just 27.04%.

Condensate recovery enhancing on offshore gas-condensate fields cannot be realized using the cycling process due to significant financial costs and technical difficulties. Such a problem could be handled by the redistribution of well gas rates. This redistribution assumes the solution the following problem: maximize the total condensate production at a given time interval then gas production requirements are met. The results of solving the problem are functions, each representing the change in the well gas rate over the time. The problem is transformed to the linear optimization model so that the solution algorithms based on the linear programing theory can be applied. Their tests showed, that these algorithms easily find the solution of the optimization problem; and the condensate recovery is greater or equal than the one obtained by the optimization procedures implemented in Eclipse. The search time is an order of magnitude less than the one required by Eclipse.

Gas dehydration is one of the main technological processes in natural gas treatment for pipeline transportation and LNG production. The main task of this research is to increase the efficiency of adsorption gas dehydration. This report presents the results of a comparative assessment and determination of the optimal thermobaric parameters of the process of natural gas dehydration with KSMG type of silica gel and NaA-BS type of zeolite-containing adsorbent. It has been shown that reducing the temperature of the natural gas before dehydration reduces the mass of loaded adsorbent, the mass of adsorber, the consumption of regeneration gas, cooling gases, and fuel gas for heating regeneration gas. Recommendations on the dehydration unit placement after pre-cooling stage in order to reduce capital and operating costs are given at the end of the article. The results are important in the design and modernization of technological processes of the LNG production.

Most mechanical connections are in one way or another exposed to some form of tear, wear, corrosion and fatigue, and likely to fail over time. If the contacting surfaces in a connection are exposed to tangential loading due to vibrations, small amplitude displacements called fretting can be induced at the surface, and might result in crack nucleation and possible propagation. The review and analysis reported herein are based on review of a wide range of studies reported in the literature during the last 25 years, which look into earlier studies around fretting fatigue in interference fit connections. In addition, a new method on how to obtain an interference fit is being mentioned as a possible way of increasing the joints fretting fatigue life. Previous investigations show clearly positive effects of finding and operating with the correct combinations of interference fit levels, palliative treatments and material choices to increase the fretting fatigue life.

Additive manufacturing (AM) process is a promising manufacturing method that can replace conventional manufacturing methods, particularly for parts with complex geometry. It is the process of joining materials layer by layer to make object directly from 3D model data. Due to the inherent manufacturing process characteristics, such products experience material anisotropy with mechanical properties not easy to calculate analytically. On the other hand, numerical simulation is becoming increasingly important to solve complex problems such as in composite materials. However, no significant work of numerical simulation is reported for additive manufactured parts. This paper reports an approach to numerical simulation of additive manufactured parts by adopting methodologies developed for composite materials. To fill the existing gap in this area, the mechanical properties of FDM parts are experimentally studied. The experimental samples are produced from ULTEM9085 material with different printing parameters. The mechanical properties of the samples are then analyzed and numerical simulation using finite element method is done to compare the results with experimental results and verify the simulation model. The main aim of the study is to devise a numerical simulation method for additive manufactured parts by adopting existing methods for composite materials.

The current study is an effort to characterize the mechanical response of panels that are used as structural elements at low temperature applications. For the above reason, plaques of aluminum honeycomb sandwich were exposed for a certain period of time at different low temperature profiles ranging from 23°C to -70°C so that possible variation of their mechanical properties due to temperature exposure to be justified. Four different temperatures namely 23°C, 0°C, -40°C and -70°C were applied to these plaques prior mechanical testing that was performed at different loading modes. Specimens were obtained from these plaques in order to study the effect of low temperature on mechanical behavior and damage response of the specific sandwich structures. Extensive mechanical testing was carried out by means of tensile, compression and bending loading and the respective mechanical properties occurring from these tests were determined. From the results occurring from experimental data obtained from mechanical testing it is evident that there is a moderate decrease of ultimate strength and yield strength of the material as service temperature decreases in tensile, edgewise and flatwise compression as well as in three point bending loading modes. Moreover a drop in temperature results in a decrease in strain at rupture at tensile and compression loading.

The structural tubular elements of the offshore platform substructure work in combined conditions of bending, tension, compression and torsion loading. Evaluation of the platform stress state is an important task. Effective solution of which can be received by a CAD modelling. The real stress state of the structure depends on the characteristics of corrosion processes. Therefore, corrosion defects should be taking into account for numerical and analytical modelling to determine/predict actual state of stress of bottom fixed offshore platforms. The stress concentration factor is the real characteristic of stress value for the structural elements of the platform in the zone of corrosion. The paper deals with the methods of the actual stress state calculation for the structural elements and welded joints of stationary platform under corrosion. The features of corrosion defects are also a subject of analysis. The proposed a calculation method of stress concentration factors for the primary tubular members of platform substructure in condition of corrosion.

Vickers indentation load-depth curve may be used to determine basic mechanical properties of metallic materials such as hardness, yield stress, modulus of elasticity, and elastic and plastic work. The pile-up phenomenon observed during indentation causes underestimation of the projected contact area and the diagonal dimensions of the impression in different hardness measurement scales (nano-, micro-, and macro-). The aim of this paper is to conduct a numerical analysis of the effect of friction conditions on the pile-up phenomenon during testing of DC04 steel sheet. The mechanical properties of the sheet metal used for the modelling purpose were first characterized by tensile tests on samples cut along the rolling direction (0°), transverse to the rolling direction (90°) and at an angle of 45° to the rolling direction. The numerical computation was conducted using ABAQUS, which is one of the powerful finite element-based programs. A wide range of variation of friction coefficients, i.e. 0-0.3 has been used in the analysis. It has been observed that the results of indentation of anisotropic materials are significantly affected by friction. The difference in the pile-up height measured at rolling direction of sheet metal and transverse to the rolling direction decreases with the reduction of the maximum displacement of the indenter. For higher values of the coefficient of friction, the higher the value of the indenter displacement, the lower becomes the increase in the pile-up height value.

This paper examines the contact stresses associated with the wedge-lock mechanism in a prototype subsea pipeline recovery tool (PRT) through numerical methods and experimental testing. The prototype PRT studied combines IK-Norway subsea plug technology in a subsea PRT. This allows the PRT to seal the subsea pipeline while it is being retrieved. The PRT can then flush the pipeline before retrieval and therefore providing for operational cost savings. This paper presents the first stage of the study which the sealing mechanism is not studied. The current wedge-lock mechanism uses a cone to press steel balls against the insides of the subsea pipeline thereby locking the PRT to the pipeline. Designing for sufficient contact stresses is critical to ensure that the PRT can grab the subsea pipeline tightly in order to ensure a successful recovery. The contact pressure distribution between the ball and cone in the wedge-lock mechanism is modelled using finite element method in Ansys. The resulting indentation depths occurring at the pipeline are compared against physical tests. It was found that the contact problem associated with the wedge-lock mechanism is complex and the actual contact stress/final gripping force is sensitive to the input parameters. Second, the results show that the Ansys numerical model is able to represent the contract stresses fairly accurately if the friction coefficient is well-controlled. Third, it was observed that a low friction coefficient ensures low indentation depths. Last, the results highlight that an increase in the cone-angle leads to a decrease in the indentation depth.

This paper examines the correlation and determination matrices of the burst design in a subsea carbon-fibre-epoxy composite flow-line. A case study of a 4" flow-line is investigated. The correlation and determination matrices are calculated and compared using Pearson and Spearman correlation methods. A comprehensive suite of failure modes that comprises of Maximum Stress, Tsai-Wu, Hashin and Puck failure criteria is used to quantify the burst design. The results reveal that the failure criteria are strongly correlated to each other. The applied pressure and ply thickness are moderately correlated to the failure criteria. It is observed that due to the nature of burst loads, most material failure parameters with the exception of the Tsai-Wu constant, F12 do not exhibit correlations with the failure criteria. Second, both Pearson and Spearman correlation methods identified the same set of major design parameters. Third, it was found that the identification of the major design parameters is not affected by the sample size. This paper provides an analysis framework to aid in the identification of the major design parameters which is the initial and crucial step of a design optimisation exercise.

An analytical solution for the dynamic response of submerged slender circular cylindrical structure subjected to linear wave loads is presented. A double Laplace transform with respect to temporal and spatial variables is applied both to motion equation and boundary conditions. The dynamic deflection of the beam is obtained by inversion of the Laplace transform. The latter with respect to spatial variable is obtained analytically, while the one concerning the temporal variable is numerically calculated using Durbin numerical scheme. Results in the case of a representative example for a monopile foundation subjected to Airy waves are presented and discussed, and the analytical result is compared against numerical dynamic and static solutions.

Reliable data on the properties of the porous medium are necessary for the correct description of the process of displacing hydrocarbons from the reservoirs and forecasting reservoir performance. The true permeability of the reservoir is one of the most important parameters which determination is time-consuming, costly and require skilled labor. The paper describes the methodology for determining the permeability of a porous medium, based on machine learning. The results of laboratory experiments, available in the database (terrigenous reservoirs with permeability in the range from 12 to 1132 md), are used to train the neural network, and then to predict the reservoir permeability. Comparison of the predicted and calculated permeability values showed a fairly good match between them with the determination coefficient of 0.92. The last task considered in this paper is to obtain an analytical expression describing a fluid flow in a porous medium using machine learning. This procedure enabled to obtain a resultant equation of fluid flow in a wide range of reservoir parameters and pressure gradients, which can be used in reservoir simulators.

A study of strength of composite materials produced by 3D printing technology is presented. The samples fabrication and tests to determine the strength both in bending and in tension of the composite materials have been carried out. The composite samples were additively manufactured using Markforged® 3D printer of type Mark-Two. The fabricated composite samples were of carbon fiber filament combined with a thermoset plastic matrix, by its producer named "Onyx". The tests provided sample mean value for the ultimate tensile strength of 560 MPa and the tensile modulus of 25 GPa. Based on the three point bending tests the ultimate flexural strength of 271 MPa and flexural modulus of 16 GPa were estimated. The tests are reported and discussed in view of stress analysis modeling the layered composite with finite element models.

The offshore oil and gas industry has been exposed to major challenges over the last decade, particularly demanding cost cuts and more effective technical solutions. Predictive systems and remaining life assessments for both machine and structural components are known to be one of the core areas that has gathered much attention lately. This paper focuses on multiaxial fatigue that is a problem in number of engineering structures and equipment. The ability to properly assess and quantify multiaxial fatigue of offshore equipment and structures has major benefits for owners of engineering assets both in terms of technical and safety integrity. Traditionally, Palmgren-Miner's damage rule is used for life estimation involving multiaxial fatigue due to its ease of use. There are however some known shortcomings with Palmgren-Miner's rule namely: it does not consider the loading sequences. This for instance can result in overestimation of fatigue life in scenarios where stress amplitudes are decreasing, and moreover underestimation of fatigue life in scenarios where stress amplitudes increase. This research work thus involves closely studying the application of Palmgren-Miner's linear damage rule, Manson's double linear damage rule, and Subramanyan's non-linear damage rule for the purpose of enhancing the predictability of damage as well as accuracy of fatigue life assessments. Each of these techniques were applied for tie-rods of an offshore drilling top-drive having a known stress history. The loading histories were provided by a drilling company. The torque and axial force values are transformed to stress components for the corresponding critical spots. The "rainflow" counting technique is applied to the obtained stress histories and the mean stress effect is considered for the damage accumulation calculations. The fatigue life prediction of the three models are justified and discussed. This research work was aimed at contributing towards the utilization of more robust fatigue life estimation techniques such as Manson's double linear damage rule and simplified non-linear damage rules which capture the true nature of the fatigue that equipment's are subjected to, and thus to improve the reliability of the fatigue life predictions.

This paper presents a numerical prediction on the assessment of natural ventilation on a livestock house built in porous panels, aided by Computational Fluid Dynamics techniques. A typical climatic environment in Cold Regions was taken into consideration. The ventilation performances have been assessed by the distribution of indoor air velocity, turbulence intensity and local mean age of air through the cases: the house without porous panels, with wind erosion porous panels, and with snow erosion porous panels. The study has found that the porous panels improve the indoor environment in term of the reduction of air velocity and turbulence, and the wind erosion panel performs better than the snow erosion panel. However, applying porous panels may have negative effects on air exchange effectiveness. The presented numerical model is easy to be constructed, flexible to investigate different case scenarios, and quick and cheap to get solutions.

Offshore foundations, namely for offshore wind, wave and tidal applications, often require the use of scour protections. Rip-rap scour protections are an important element of the foundation to ensure that the natural frequency stays within the design limits. Scour protection design still presents a remarkable empirical nature, which typically leads to uncertainty on their behaviour under extreme met-ocean conditions. Therefore, reliability assessment of scour protections has been seen as a possibility to account for design uncertainty and to optimise the scour protections. However, the definition of a suitable limit state function is still a matter of research focus, namely, regarding the proper definition of the acceptable damage level for dynamic scour protections. This research provides a brief review on the recent studies related to both the limit state function and the calculation of damage numbers through bathymetric data. A discussion is raised on how the methodologies for calculating the damage number may influence the limit state function and a theoretical example is given to assess the effects on the probability of failure. Results have shown that the acceptable damage number requires a clearer definition, which should be based on the number of layers of rock material and the area of filter exposure. In addition, this research highlights the need for alternative ways to assess damage.

Reliable fatigue design rules affect the proactive identification of safety parameters in engineering structures. Numerous fatigue crack initiation and propagation models, linear and nonlinear, have been developed for designing purposes or estimation of the remaining life of aging structures. Depending on the adopted assumptions, the accuracy varies for different loading histories, loading types, and materials. Semi empirical models are simple but yield significant inaccuracies. Models with better theoretical basis provide better accuracy, but implementation in real conditions is problematic. In the present work, a review of author's recent fatigue crack initiation and propagation models based on physical mechanisms is presented and improvements are proposed. Verification of the models on test results is provided and discussed.

This paper presents the experimental test results for the buckling capacity of tubular columns exposed to simulated unsymmetrical patch corrosion damage. These tests were performed to investigate how the results of these experiments compare with the capacities obtained for the formulae provided in the 2004 revision of NORSOK N-004. Formulae for patch corroded tubular columns are needed in standards and as such it is unfortunate that these formulae are removed from the present revision of the NORSOK N-004 standard. Prior to suggesting introducing these previous formulae in standards, experimental tests to confirm good correlation between experiments and formulae are needed. The tests performed in this work are presented in this paper for 100% (intact columns), 69%, 34% and 0% remaining wall thickness in the patch.

Probability-informed inspection planning has traditionally a tendency to produce longer inspection intervals for older structures in contrast with the intuitive assumption that shorter inspection intervals are needed. In this paper an alternative method for probability-informed inspection planning is suggested based on a parameter updating rather than the general updating used in most cases. The proposed method produces constant inspection intervals after the theoretical first inspection. Further, the method produces reasonable inspection intervals more or less in line with what is used in practise in the offshore industry at present.

In fatigue management, it is essential to know the fatigue crack growth potential. The lessons learned from use of refined fatigue analyses, fracture mechanics and probabilistic methods for platforms in-service are presented. For ageing offshore units of semi-submersible design, the inspection history of more than 20 000 NDT inspections and detection of close to 1000 fatigue cracks, are used in this study. These experience data are used to assess the fatigue failure potential. The fatigue crack growth capacities are influenced by the extent of gross errors in the design, construction and operation phase in addition to the normal uncertainties of design, construction and inspection. Corrosion in combination with not detected weakening of the capacity against fatigue crack growth is one of the main challenges. Assessments based on collected in-service observations are mandatory.

This paper presents the formulation and characterization of composite fly ash and slag based geopolymer concrete. Potassium hydroxide (KOH) and potassium silicate (K₂SiO₃) liquid alkaline activators were used in the preparation of the geopolymer concrete. The mechanical response of the best recipe was investigated through compressive, tensile and flexural strength tests after 3, 7 and 28 days of curing. One batch was tested for compressive strength after 16 and 32 weeks of curing. The microstructure of the concretes was characterized using scanning electron microscopy (SEM). The testing results are compared with a reference ordinary portland cement-based concrete. After 28 days of curing, test results showed that the geopolymer concretes can approach the compressive strength of the reference ordinary concrete. Moreover, the tensile strength and flexural strength attained reached up to 68% and 80% of the reference cement, respectively. The results indicated the potential application of geopolymer that can satisfy the standard strength requirement. After longer time of curing, 32 weeks, some of the geopolymer preparations exhibited 111% compressive strength, compared to the ordinary cement reference.

Predictive maintenance (PdM) and operations optimisation are expected to generate the highest industrial and societal impact within the oil and gas industry. Such an optimistic expectation requires several changes in asset design and maintenance management. Nowadays, design for maintenance and maintenance support needs are mainly guided by the IEC 60706-2 standard. However, Designing for PdM ready-equipment is not yet part of that standard. To design PdM ready-equipment a specific analysis method shall be performed to evaluate the technical requirements and specifications of designed equipment to be PdM ready. Therefore, the purpose of this paper is to propose and demonstrate a PdM analysis method that helps to specify the technical specifications to monitor and predict the health of a specific physical asset. The proposed matrix is an evolution of further development of failure Mode, effect and criticality analysis (FMECA) and failure mode symptoms analysis (FMSA) rather than a revolutionary analysis. The case study method is used to extract stakeholders needs of what they expect from PdM analysis (PdMA) and how practical such type of analysis shall be. The developed PdMA matrix shows a simple relation between failure (their modes/levels) and measured abnormal symptoms and tracking and prediction indicators. The electric generator is used to demonstrate the use of the matrix. The PdMA matrix can be developed further to be more quantitative by including the probability of detection and probability of prediction.

The paper presents a novel process for probability-informed inspection planning based on the following principles. 1) A description of the strength of knowledge about a problem shall be included and be accounted for in the decision making, 2) Probabilistic methods should be used to predict quantities expressing the physical reality of nature (observable quantities) and their uncertainty, and 3) Any update of the probabilistic model should be limited to the actually observed quantities. The process for updating the probability of failure after inspection is programmed in accordance with these principles based on Monte-Carlo simulations and Bayesian parameter updating. The application of these principles and the proposed process is illustrated by an example calculation resulting in an example of inspection intervals for a jacket structure.

Offshore structures are conventionally designed for a service life between 20-30 years and mostly used beyond their service life. They are operated up to the point where costs of operations, maintenance and repair exceed the revenue generated by the offshore structure. The cyclic nature of environmental loading induces multi-axial stresses with high gradients in welded tubular joints that lead to fatigue cracks emanating from imperfections in the welded materials. Tubular joints may exhibit significant residual life after fatigue cracks formation due to crack propagating around the weld circumference. It is important to understand tubular joints behaviour and estimate the residual life beyond crack initiation as it promotes the safe operation of the offshore installation, inspection planning and life extension of the asset. This paper presents an overview of the residual life estimation of cracked tubular joints using numerical methods. The recent developments and possible enhancements to the modelling methods of cracked tubular joints are presented.

General widespread corrosion is of increasing concern for structural reliability of ageing marine structures, particularly for semi-submersible pontoons. Conditional failure rate, also termed hazard function is sought to describe the increasing maintenance required with age. Literature is reviewed connecting corrosion degradation to hazard rate, either through a time degrading limit state function, or statistical data for time to failure. Here, a rule based failure definition is applied based on corrosion tolerance levels, together with a linear corrosion degradation model to make a time variant limit state function. Monte Carlo simulation is applied based on statistical models for the basic variables including importance sampling, to obtain the time to failure distribution from which the hazard curve is deduced. A more realistic hazard function is also produced, requiring average of 3 simulations to exceed the tolerance in order to fail. It is seen that this approach delays the increase of the hazard curve, at the expense of higher failure rates.

Vessel activities such as trawling and anchoring potentially affect pipeline integrity. Therefore, the detailed information about the trawl activity in the area is essential for accurate assessment of pipeline, where to inspect and where to implement corrective intervention, based on up to date trawling intensity and equipment used. The main contribution of this paper is to present a detailed analysis of trawling vessels activities based on the automatic identification system (AIS) data combined with DNV GL ship register, data from HIS Maritime World Register of Ships and information gathered on the trawl equipment. In this aspect, an interactive web-based solution has been designed and developed to monitor and track trawl vessel activities in the Norwegian Continental Shelf which can be used for assessing integrity of pipelines. Data Analysis and visualization techniques have been utilized to transfer high-dimensional data by encoding it as visual objects contained in graphical presentations. The extracted knowledge result in the density mapping, vessel tracking, computing crossing points of trawl vessel paths, computing a buffered polygon around the pipeline for the chosen threshold and cross-over statistics of pipeline and vessels, etc. The use of such a framework is mostly advantageous for the port authorities, marine transportation, relevant fisheries management authority, etc.

This paper presents an efficient method for collision design of prestressed concrete pontoon walls. High fidelity finite element models of a container ship bow and a prestressed concrete pontoon wall are first established. Integrated numerical simulations are conducted to study the structural deformation of the pontoon wall during the collision. Parametric studies are also carried out to investigate the effect of the pontoon wall thickness. Based on the failure mode of the pontoon wall, a punching shear check procedure is proposed. This method yields a good accuracy while significantly reduces computational efforts. Hence, the proposed approach can be used for collision analysis in the preliminary design phase of floating pontoons.

The principles for ULS design and ALS design for offshore structures are discussed. The use of pressure-area curve versus force-area curves for analysis for estimation of ALS impacts is deliberated. Aspects of local and global shape of the ice feature are discussed in view of external mechanics (demand for energy dissipation) and internal mechanics (local damage). Simplified methods for structural damage assessment are reviewed for ice loads that may move both transverse to and along the shell plating. Material modelling of ice for nonlinear finite element analysis (NLFEA) of ice-structure interaction is reviewed. The material models must be calibrated against design curves and the sensitivity of the material parameters with respect to mesh size is investigated. Results from simulation of impacts of ice with different shapes on the column of a floating platform are presented, and the critical shape for penetration of the front plating for the present structural configuration is identified.

The stringent requirements of the IMO's emission regulations call for alternative fuels and new ways of powering ships. However, the IMO predicts that technology which could reduce ship emission to zero, will either not be available, nor cost-efficient over the next 40 years. However, technological innovations in ship power & propulsion systems; such as duel-fuel LNG engines, and the utilization of energy storage technology in the form of lithium-ion batteries have been found to reduce harmful emissions; and are already utilized to quite some extent in the offshore support fleet. This paper elaborates on the reliability and sustainability of newer ship power technologies, where equal to existing levels of reliability are expected as a minimum.

The composition of water changes with temperature, for instance, the saturation rate of water in polyurethane membranes is related to the temperature. Thus, it is necessary to evaluate the influence of the composition of water on absorption of water in subsea cable insulation. This paper is suggested to represent a supplement to existing standards regarding "Electrical insulation materials - properties with regard to thermal long-term behaviour."

Developments of hydrocarbon fields in the Barents Sea would normally include surface process units; thus, we must take into account the ice conditions in the area. Alternatively, smaller fields can be developed as satellites to existing production units. Full well stream to shore facilities may also be considered, in the case that one can document the flow conditions in the pipeline(s). Although glacial ice historically has been present all over the Barents Sea, the probability of meeting glacial ice in the southern part is very low, regarded by many as "negligible". At which latitude one could expect sea and glacial ice in the future is, however, uncertain, as past experience has seen glacial ice on the Coast of Finnmark County and there are ongoing processes related to global warming which might increase the probability of iceberg encounter at the location. We will discuss concerns related to the selection of the design basis for the Barents Sea, including the Russian part of the Barents Sea, and discuss the term "negligible". Of particular interest are criteria for the need for disconnection options for production units. The paper concludes with recommendations for thorough preparation of the design basis for the entire Barents Sea area.

The environmental conditions in the Barents Sea include low temperatures, wind, snow and precipitation influencing safety, working environment, operations and equipment functionality. The conditions are not extreme compared to other Arctic areas, however they do necessitate protection and winterization of the facility. A study performed for the Petroleum Safety Authority (PSA) in 2016 identified known measures for winterization of facilities in the Barents Sea. The study found uncertainties related to the effect the measures have on winterization when considering environmental conditions. Further work was recommended to evaluate the effect of measures when considering performance influencing factors. A new study was initiated by PSA to develop a method to evaluate the efficiency of measures and a means to document the results. The method considers how well a measure achieves a specific safety and winterization goal, effect of the measure on energy consumption, effect of the measure on investment cost and operating cost, and vulnerability of the measure, including operational and organizational factors. In order to refine and test the method, it was applied to case studies considering a year-round production facility, a light well intervention vessel and a drilling facility used in the winter season in the Barents Sea. The paper is not intended to be a research paper but is a presentation of a method that has been developed to perform an initial evaluation of the effectiveness of winterization methods.

Risk analysis/assessment is one of the challenges encountered during operations of offshore units on the Norwegian Continental Shelf (NCS). In recent years, the Petroleum Safety Authority (PSA) has focused on hazards relating to floating installations and thus requested that more attention should be made by the industry on hazards relating to buoyancy loss and stability. Ballast systems play a very vital role to ensure vessel stability. Various failure modes of semi-submersible ballast systems are identified and possible barriers and consequences due to the ballast system failure during drilling operation are considered. The failure mode effect and criticality analysis (FMECA) of the main components of the semi-submersible's ballast system is adopted to determine the failure causes and failure modes that could influence each components performance, and thus identifying the most critical component(s). The Structured What-If Technique (SWIFT) is used to compensate for hazard identification for the unidentified hazards (i.e., human errors), in the FMECA. By studying the most critical system components, a qualitative risk analysis is conducted to model accidental sequences by using the fault tree method to establish the chain of failure events. The result of the Structured What If Analysis (SWIFT) shows that maloperation of the ballast system is the main contributing failure cause. This involves, failure to properly describe ballast procedure, failure to follow ballast plan, wrong sequence of closing/opening valve, maloperation of valve, time pressure complacency, communication gap or general lack of knowledge of the system. The FMECA findings indicate that failure of valves to "close on demand" with a Risk Priority Number (RPN) of 60, is the most critical.

Participation in exercises lead by the University of Stavanger, the SARex 1 in 2016 and SARex 2 in 2017, provided valuable lessons related to survival in a cold maritime environment. The scenario of the exercises was a mass evacuation from a stranded cruise ship in Arctic waters but provided experiences relevant beyond the cruise industry. This article focuses on the relevance for the oil and gas industry in the Norwegian sector. SARex 1 and 2 were rescue exercises carried out north of Spitzbergen by industry, regulators and academia during the spring of 2016 and 2017. The Norwegian Coast Guard, the University of Stavanger and GMC, Stavanger, organized the exercises. The Petroleum Safety Authority found it important to participate in SARex 1 and 2, to better understand the factors enabling success in a cold climate survival situation. The survival tests in lifeboats and life rafts during SARex 1 and 2 showed the necessity of having trained and competent leadership on board. This issue has perhaps been neglected, compared to the development of equipment to ensure successful evacuation and avoid hypothermia. Some key factors for survival success were (1) Functioning of emergency equipment (2) Organising and teaching the function of various items of safety equipment (3) Operating evacuation means at sea, e.g. watch routines, operating hatches/venting routines and (4) Activities and maintaining mental awareness and motivation. The overall learning from SARex 1 and 2 is that survival is dependent on active participation from the survivors. There is a need for sufficient competence amongst personnel to micro-manage all the details required for survival. The mental factors following fatigue and seasickness, in addition to hypothermia, make leadership and competence in a cold maritime climate essential for survival.

The development of the Arctic region will entail the construction of new infrastructure, in particular, subsea pipelines. Considering the lack of actual field practice, ecosystem vulnerability and lack of common Arctic international standards, their development will be a big challenge, in particular, in the shore crossing zone. The design and construction of pipelines in the shore crossing area require a special approach that takes into account environmental and technological aspects of development. This work is aimed at analysing and determining environmental and technological factors influencing the design of offshore pipelines in the Arctic coastline. The paper presents theoretical and analytical work and the research is applied to a specific case study (pipelines from the Leningraskoye field to shore), through engineering calculations. Currently, there are five Arctic projects with shore transition areas for which trenching has been implemented. In order to determine the best shore crossing approach, it is important to consider the following environmental conditions: ice encroachment; ice ridges; shoreline erosion; permafrost thawing. Environmental characteristics should predetermine the choice of approach. Among three existing methods: trenching, tunnelling and horizontal directional drilling (HDD), the micro-tunnelling method is recommended for the Leningradskoye field in combination with a cofferdam corridor to protect the buried pipe from waves and ice in the nearshore area. In order to protect the surrounded permafrost from melting seasonal cooling-device is recommended to be used. The burial depth is determined to be more than 3.52 m in accordance with Force model calculations of ice ridges scouring depth. On the basis of research, the general choice-making diagram was proposed for Arctic shore crossing areas.

In recent years, one of the most important direction in the development of offshore hydrocarbon exploration is the expansion of the oil, gas and gas condensate fields of the Russian Federation to the Arctic shelf areas. Extensive and complex engineering surveys are actively performed in the Barents Sea and the Kara Sea. In the last year, a wide range of engineering investigations has been implemented on prospecting and exploratory wells. The geotechnical surveys are mandatory before the drilling of exploratory and production wells to obtain the data for the upper part of the geological profile to provide necessary information for safe positioning of drilling rigs. This is extremely important as the upper part of the soil interacts with an engineering structure whether it is a drilling rig, pipeline, subsea production system or any other structure. The data of the stated surveys is used for optimal location selection for drilling rig positioning and the necessary stability calculations. The use of geophysical and geotechnical methods in engineering surveys provide an effective solution for the geological challenges and ensures the availability of sufficient information regarding soil composition, properties and strength conditions.

There are a number of geological and hydrogeochemical modelling techniques used in order to ascertain formation of the hydrogen sulphide (H₂S) in the formation fluid within a geological setting in several blocks of the Norwegian Barents Sea. Careful consideration of the regional and chemical factors causing H₂S generation can also be used in the drilling context. Thermochemical sulphate reduction (TSR) is the most likely process of H2S formation in this setting. Risk picture becomes different when presence of H2S is closely coupled with occurrence of Permian and Carboniferous carbonate plays prone to causing severe drilling fluid losses and increasing exposure time of the downhole equipment to the H₂S. Using appropriate analogues and adequate well offset analysis tend to demonstrate that most of the risk factors can be well mitigated.

The article describes a unified approach to the assessment of resources and business planning. As an example, the oil and gas resources of the Pechora Sea are considered in the paper. Based on the specifics of the problem (the quantity and quality of the available data and their nature), the methods of multicriteria fuzzy clusterization are used. The assessment of the prospects for the development of oil and gas fields was carried out using 3 criteria, namely: availability of resources (natural and climatic conditions of the region); hydrocarbon resources and their degree of exploration; economic assessment of the development. The results of such an analysis are presented in the form of maps of the Pechora Sea area, illustrating the most important and accessible areas and the sequence of their development. Such a stepwise development based on minimizing the risk and maximizing the benefits can be the basis for the successful and trouble-free development of the resources of the entire region.

The article is devoted to the systematic solution of problems of multi-criteria assessment and the possibility of implementing projects for the development of hydrocarbon deposits on the Arctic shelf under conditions of uncertainty and risk. Risks are considered in a narrow and broad sense. It is shown that the solution of tasks, in this case, comes down: 1) to a multi-criteria assessment of the quality level of a field based on a hierarchy analysis method that takes into account uncertainties and risks of operating objects through the relevant necessary indicators (criteria); 2) determining, with the help of game theory adopted with the nature of the criteria for selecting the best Bayesian strategies, of development options under both partial and full uncertainty conditions; 3) selection using the rules of the Borda, Pareto and multi-criteria dispersive risk model for choosing the best development strategy.

Cold climate areas that provide opportunities for the remote inspection of pipelines include the Barents Sea, the Russian Arctic, the Alaskan Chukchi Sea, the Beaufort Sea and the Canadian Arctic offshore. First, an analysis of several actual projects of contactless diagnostics using the magnetic tomography method of pipelines in Arctic conditions is done. Second, the Risk-Based Inspection methodology for Arctic offshore pipelines is discussed. It involves ensuring pipeline reliability on the basis of data on the technical condition of the metal in actual operating conditions. The magnetic tomography method allows not only to remotely identify areas of anomalies with metal defects, but also to register mechanical stress levels taking into account actual loads. This reduces the risk for the structure to come to the critical state in terms of exceeding local loads. Finally, magnetic tomography technology allows managing risks in cases of local corrosion, stress cracking or loss of stability of underwater pipelines in areas with free spanning. The qualitative indicators of the inspection include the probabilities of identifying, interpreting the degree of danger, missing a dangerous defect. The pipeline diagnostics report provides the parameters of reliability forecasting: the period of incident-free operation, safe working pressure, and pressure coefficient.

The development of the digital transformation of the gas industry in the Russian Federation is mainly aimed at unique and giant fields. These fields provide the leading position of Russia in the world gas market and about 85 % of the total volume of gas production. The regulatory and technical base, the composition of the existing standards allows us to move to the practice of introducing digital gas technologies. The creation of a unified integrated model is being completed at the Bovanenkovo field. The creation of a digital twin of a unique gas field represents the transfer of a real field into virtual space through the use of Big data analytics and supercomputer technologies.

Precise estimation of the effective petrophysical characteristics for the oil or gas-bearing reservoir plays a vital role in production control problems. It is preferable to use nondestructive measurement methods for porosity, conductivity, geomechanical modulus, and some other parameter fields. For the estimation of anisotropic permeability tensor flows in different directions need to be simulated in the core plug digital image void space, which is very difficult (if possible) to conduct with the real rock sample. The creation of the digital core image includes three stages: construction of its internal structure based on the computed tomography (CT) sinogram, filtration, and segmentation. Routine practice is the filtration of 2D slices pack of the core plug CT image because of a lack of computational power and memory limitations. Unfortunately, this can generate a directional orientation error orthogonal to the pack of slices. The total 3D edge-preserving filtration with the usage of two approaches: modified implicit anisotropic diffusion and discrete orthogonal transforms can reduce this error. Universal code based on the MPI+OpenAcc programming paradigm was tested on different high-performance computing systems incorporating various accelerators like GPGPU and heterogeneous processors such as Sunway 26010.

The application of data assimilation methods for field development optimization has been the subject of intense investigation during the past 10 years. Lately has seen remarkable progress in the ability of data assimilation approach in reservoir characterization and based on this, improvements of field development optimization. In this review paper, we have summarized key achievements in field development optimization of waterflooding process with data assimilation approach and review many of the achievements of the past time, including developments in the field of search for modifications of Ensemble Kalman Filter (EnKF) and Ensemble Smoothers (ES). An attempt has been made to discuss different data assimilation methods and to identify possible limitations of each. Current challenges and future research opportunities for improved data assimilation methods for field development optimization of waterflooding process are also discussed.

In the study the existing approaches for stabilization time estimation are given and compared with the results of hydrodynamic simulation. A deviation from an assumed ellipsoid shape of drainage area has been observed for a horizontal well based on the simulation results. Then this geometrical definite form was taken into account in the gas influx equation. On its basis the time period of pseudo-steady state was estimated. As a result, stabilized horizontal gas well tests are considered to be not effective as the time period is too long when pseudo-steady state is reached and it's impossible to carry out the test in reality. However, it is suggested to continue a well test for a reduced period by adapting well tests on the model and matching simulation output with gauge measurements.

SICLO (Source of data and information; Input data; Calculation/Analytic; Logic Analysis; Output/Value Delivery) methodology is an innovative concept for smart diagnostic, reservoir/well performance optimization and estimation of remaining reserves based on the integration of Petroleum Data Management System (PDMS) and expert rules. Implementation of SICLO methodology provides the best strategy on how to produce remaining reserves most profitably. PDMS is the foundation of SICLO methodology and provides structured and verified information that follows the Well Life Cycle. Within PDMS, data are organized and structured according to clearly defined principles and rules and filtered by different levels of quality control. Structured data allows integration of production and reservoir information with real-time data to achieve the maximum level of diagnosis of system operation performance according to reservoir and well potentials and system constraints. The built-in workflows and architecture of the whole process are automated and make the task accomplishment faster. SICLO methodology integrates expert-driven knowledge and pattern recognition tools improved by data-driven, artificial intelligence, neural network, and fuzzy logic technologies to deliver adaptive solutions for identifying locations of remaining reserves, optimizing oil and gas production, and minimizing associated operational costs.

Many multiphase flow lines are prone to hydrate formation unless prevention methods are put in place. Chemical management of hydrate formation is traditionally done with thermodynamic hydrate inhibitors but in the last 25 years low dosage hydrate inhibitors (LDHIs) have been developed which can offer economic, environmental and other benefits. LDHIs are divided into two main categories, kinetic inhibitors (KHIs) and anti-agglomerants (AAs), both of which are successfully being used in field applications. This paper briefly reviews the hydrate management tools available to the operator. Then the review focuses on LDHIs, their structure-performance relationships and the various classes that have been designed and tested. The environmental challenges of both AAs and KHIs are also discussed.

Bergy bits and growlers (i.e., glacial ice features with a waterline diameter < 15 m) travelling with waves are identified as risk to the integrity of offshore structure and ships operating in the high North. It is generally more difficult to detect and monitor these small ice features and apply concurrent ice management operations. Therefore, it is important to study the corresponding damage assessment of a potential impact with such glacial ice features. Traditionally, while carrying out a structural damage assessment, the ice feature is often treated as a rigid body, whereas structural deformation and fractures are simulated with, e.g., NonLinear Finite Element Method (NLFEM). However, this method is too conservative and neglects that the ice feature crushes and dissipates part of the impact energy (often obtained with the so-called external mechanics). On the other hand, it is possible to treat both the ice and the structure deformable, and a fully coupled simulation can be carried out with NLFEM. This method can capture the physical essence that the impact energy dissipation is shared by both ice crushing and structural deformation, thus leading to a less conservative structural damage assessment. However, this method is often too computationally expensive and can only take care of the so-called 'internal mechanics' part. In this paper, we propose an integrated approach. This approach is mainly based on the innovative Simulator for Arctic Marine Structures (SAMS) to calculate the impact energy following the principle of 'external mechanics'. Afterwards, the simulated results are integrated with NLFEM simulations to re-construct the shared impact energy dissipation between both the ice feature and structure. A case study regarding a glacial ice feature (diameter = 15 m) impacting a semi-submersible is carried out in this paper. This integrated simulation approach (i.e., SAMS + NLFEM) is proved to be significantly more effective than the fully coupled analysis; more versatile and less conservative than the limiting scenario analysis when dealing with the impact between ice features and man-made structures.

In petroleum industries, waxy crude oil is normally found in petroleum production. Wax formation and precipitation during pipeline transport of waxy crude oils can cause several challenges, including wax deposition and flow reduction which adversely impacts pipeline performance in oil and gas production. To overcome the wax deposition problem, the small amount of chemicals like wax inhibitors can provide an effective preventative measure. One of this mechanism is to reduce the pour point temperature. In this work, oil from Sirikit Oilfield in Thailand is selected for this study. The wax inhibitors are selected and studied the performance for pour-point reduction. These chemicals are Polyalkyl methacrylate (PAMA), Poly(maleic anhydride-alt-1-octadecane) (PMAO), Polyalkyl methacrylate-co-ethylene glycol (PAMAEG) and Copolymers of maleic anhydride (CPMA) with the concentration ranging from 100 to 1000 ppm. Also, n-pentane with the concentration of 5-20 % by weight is used as a solvent for wax inhibitors. The results from this study show that n-pentane can reduce the pour point to 39.41 % compared to the original oil. Furthermore, among the polymer group, PMAO can reduce the lowest pour point to 52.82 %. In addition, the mixed solvents of polymer with n-pentane can provide relatively less effect on pour-point reduction. The mixture of n-pentane with PMAO can lower the pour point to a certain level of 54.96 % compared to the original oil. This study can be applied to use in the real field to prevent wax deposition in the pipeline transportation for oil production.

The report describes the method of the acoustic impact on the oil reservoir. Chemical decomposition of formation water molecules occurs with the help of energy-accumulating substances. Water becomes a supplier of hydrogen and oxygen. This allows the processes of hydrogenation and synthesis of new compounds. The decomposition of water is carried out using activated aluminum. As a result of the reaction, hydrogen is released, which provides the reaction of hydrogenation of all fractions of heavy oils. Industrial tests of the new method of acoustic impact were carried out at one of the fields with high viscosity of the Embamunaigas company in 2016. Pilot tests revealed an increase in the flowability of heavy oil during the hydrogenation of its components. The increase in well productivity was recorded during the first days of testing a new method. The negative side of the tests was the colmatation of the well with the released aluminum oxide. Physical and chemical processes on the surface of the reacting components were studied. In the course of the research, the state of the phase interface was studied. The spectral composition of the responses at the phase interface was measured. The report presents the results of measurements of the spectral response of water to external influences. The test results of the new acoustic method showed the need for additional research.

The extraction of heavy oil, including bitumen, is complicated by the extremely high viscosity of the fluid in the reservoir. The adsorption of heavy oil fractions on the surface of minerals leads to the hydrophobization of the pore space. The magnetic colloidal particles of iron oxides present in the composition of the water remove adsorbed oil from the surface of pores, which manifests itself as an increase in the oil recovery factor and the injectivity of injection wells. Iron particles of submicron size, located on the surface of an electrically charged gas bubble, are concentrated at the water-oil interface. Due to the high adsorption energy on the surface of the iron particle, oil is deposited on the iron oxide particles. The drop-in bottom pressure of injection and production wells contributes to the movement of the gas bubble with oil and iron oxides to the bottom of production wells. The study of the mechanism of exposure to electromagnetic radiation showed that the electromagnetic field selectively heats the particles of iron oxide, causing catalytic cracking of oil, and contributes to an increase in the oil recovery factor and well productivity index.

Purpose of this report to inform the petroleum readership of recent advances in areas of the associative polymer flooding. Polymer flooding is the industrial enhanced oil recovery method, which successfully has applied in various types of reservoirs. The polymer flooding for high-temperature and high-salinity reservoir faces enormous challenges. Hydrolyzed polymer has been used as the main polymer type for the polymer flooding. Now researchers have turned their attention to associative polymer solutions. This report presents an overview of the associative polymer flooding. Some recent projects have shown an expanding technology. This report reviews published results of the use of associative polymers to enhance oil recovery in recent years. The associative polymer flooding is one enhanced oil recovery (EOR) method being developed recently to increase the oil supply. Polymer flooding application in high-temperature and high-salinity reservoirs is currently limited by polymers chemically and thermally degradation at high temperature and salinity. The associative polymer solutions improve the over-all reservoir conformance by providing mobility control. Water is injected after the polymer solution. Based on the number of new laboratory and pilot tests, field activity is continuing at a moderate level.

Industry 4.0 vision and associated technologies are rapidly adopted in several industrial sectors to gain the benefits of creating smart cyber-physical systems and operations. Some sectors, e.g. manufacturing, oil and gas, offshore wind energy, have progressed in developing digitization strategies, executing pilot projects and progressing toward mature implementation of industry 4.0 vision. Offshore Oil and Gas industry highly believes in the potential industrial and societal impacts of digital transformation, due to the need for stochastic and remote operations. Azerbaijan as one of the countries that heavily depend on the Oil and Gas industry is developing more projects in the Caspian Sea. There are several worldwide challenges, mainly, lack of standards, business models, ready products/services and competent and skilled employees. Fortunately, specific developed countries are working hard to standardize industry 4.0 architecture. Moreover, large-scale companies are creating alliances to create a trustful and long-term business model. Furthermore, large-scale companies of information and operational technology are creating robust products and services to be commercially available off the shelf. In terms of education and training, many worldwide universities are upgrading their programs, curriculums, teaching approaches with the goal to support the industry with competent future employees and entrepreneurs. Therefore, the purpose of this paper is, to present the status of engineering education programs in adapting the industry 4.0 vision in Azerbaijan and address the skills that are required for future employment. In order to present the targeted status, the curriculums of all engineering education programs at the master level were collected and analyzed. However, five of them were directly adapting industry 4.0 vision and relevant for industry 4.0. Moreover, a semi-structured interview with industrial managers was applied to extract the future required skills. This study can be considered as a first step in developing a roadmap for engineering education, particularly industrial engineering, to adopt industry 4.0 vision at the national level.

Wind energy is a source freely available in the oceans. New developments in the wind industry are towards high altitude wind turbines, known as Airborne Wind Energy Systems. The airborne wind technology is rapidly developing with several different design concepts, e.g. Skysail, Makani, KiteMill. There are mainly two types of airborne wind technology: propulsion-supporting and electricity-generating. Electricity generating airborne technology is mainly used for land-based buildings and fixed offshore structures and with small-scale airborne turbines. Thus, the applications of this technology in the maritime industry are limited to ship propulsion-support only and no scalable airborne wind turbine is used on board of a vessel. Therefore, the objective of this study is to explore the application of electricity-generating airborne turbines on the board of a ship. The exploration is mainly to determine how scalable these turbines shall be to satisfy a ship's electricity needs and how compatible the design of these turbines can be with the ships design. . Therefore, a scalability analysis based on crosswind kite power model is applied to determine the technical requirements to scale up the existing airborne turbine to meet the electricity demand of a ship. Moreover, a compatibility analysis is applied to determine the technical interfaces and constrains between the airborne turbine configuration and the ship architecture. In this case, a commercial electricity-generating airborne turbine and a commercial floating storage unit are considered as part of the case study. The developed scalability model indicates that the traction force is the most critical design parameter to scale up a wind turbine. On the other hand, the developed compatibility model shows that there is a notorious complexity in merging airborne and ship technology due to their contexts. Consequently, this research appears to be relevant for both, the airborne technology industry and the maritime industry toward more innovative and cost-effective applications.

The in-land and nearshore fish farming is facing capacity limitation and onshore push-out regulations. Huge technological innovations are rapidly evolving toward developing competitive Offshore fish farming. These technological innovations are mainly targeting to innovate new farming concepts that dynamically stable, reliable and compatible with offshore environmental loads and conditions. The dynamic operational behaviour of each farming concept is quite complicated. It is a combination of reinforcing behaviours (Loads, cage deformations, welfare issues, e.g. escaping, stress-related disease) and leveraging behaviours (Biofouling-cleaning, Deterioration-maintenance) and all influenced by fluctuating and harsh environmental loads and conditions. Therefore, the purpose of this paper is to analyse the context of offshore fish farming and explore quantitative descriptions of its reinforcement and leveraging behaviours. The context analysis is a well-known method within systems engineering methodology to illustrate and extract critical interfaces. The context analysis is considered as the first step in building simulation model to quantify the impact of systems interfaces on the entire farming economics, i.e. income and cost.

This research investigates a solar thermal system and a solar photovoltaic system which produces local energy, by incoming solar radiation, to meet the energy consumption demand of a residential building in the arctic region. The study on the use of the solar systems in the arctic areas is rare and often doubted. So, to analyze the potential of solar energy, a study case of an existing building block in Narvik, Norway was selected. The performance and function of both the systems were studied and achieved by calculation and simulation models of the thermal system and the PV system separately. The solar systems met the energy demand of DHW and space heating during summer due to the availability of the sun for long hours. However, in winter, especially in December and January, the energy production was zero due to snow accumulation and minimum sunlight. The results showed that the solar thermal collector produced about 14315 kWh throughout a year, whereas, the PV system generated an annual energy output of 18640 kWh. Thus, the results suggest considerable potential for solar utilization, however in the current context cost can be a limitation.