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In this paper, we address the problem of high greenhouse gas emissions from oil and gas platforms in Norway. We look at the potential of integrating an energy system composed of wind turbines and battery systems to unload the electrical power generated by gas turbines being the main source of emissions today. We propose a simulation model of the energy system, the power demand, the available wind speed, and different control strategies. By putting the models together, we evaluate the performance of various compositions of the system and determine their impact on emissions and battery lifetime. The numerical results show that changing today’s practices has great potential to reduce greenhouse gases, with amounts varying between 30% and 80% compared with today’s level.

The Molikpaq drilling platform, a steel annulus filled with sand, 90 m wide, was deployed at the Amauligak I-65 location in the Beaufort Sea during the 1985–1986 winter. It was heavily instrumented for measurement of ice loads, using strain gauges, extensometers, and Medof panels. The original calibrations of the Medof panels were used to estimate loads. Calibration was carried out using uniform pressures up to 1.86 MPa. The actual loading in the field of the Medof panels was extremely non-uniform spatially, particularly during ice crushing, and is very different from that in the original calibration. The resulting high pressures led to softening of the polyurethane buttons in the panels, including the Mullins effect. The panels were consequently reading too high. Extensometer readings, geotechnical measurements, and those pertaining to a decelerating floe impacting the structure, support the conclusion that actual ice loads were about half those obtained using the original Medof panel calibrations.

A combination of factors including environmental, resource availability, investor weariness and public perception of the oil and gas industry challenge the competitiveness of the sector in Norway and around the world. One frequent topic of discussion addressed in these areas of concern, as well as an opportunity for improvement, is the generation of CO2 from upstream oil and gas production. Forecasting these emissions serves many purposes and may alleviate some of these challenges while benefiting the environment. Currently, emission forecasting in the industry may not meet current needs, are complex, and can be done more simplistically. This study has aimed to produce a novel and simplified means to estimate upstream oil and gas emissions. Through a data-driven statistical method, emission and production volume histories as well as drainage strategy at the asset level were analyzed to build two emission models. The methodology derived in this thesis is not currently used in upstream emissions calculations and is novel for the oil and gas industry. The results of the modeling demonstrate the models’ ability to approximate emissions using less data, resources and knowledge than were previously needed while also providing a level of accuracy desired for industry workflows including already established requirements for project and business development in Equinor. The benefits these models provide allow emission forecasting to be less hindered by data requirements, more able to meet today’s growing demands and accelerate decision-making abilities to meet future needs. Further, the methodology is flexible and applicable to numerous industrial process which signifies a green light for expanding the use of data and furthering digitalization efforts within the oil and gas industry and elsewhere.

Master's thesis in Environmental engineering As part of a Joint industry project (JIP), Norwegian Technology has developed a new treatment technology for oil contaminated drill cuttings (OCDC). The technology is intended for offshore use at the Norwegian Continental Shelf (NCS). In order to allow for offshore treatment and onsite discharge, the drill cuttings need to meet requirements set by the Norwegian Environment Agency. According to the Oslo Paris commission (OSPAR), the maximum oil content on drill cuttings should be below 1 wt% and for the Norwegian Environment Agency a maximum oil content on drill cuttings varies but is often below 0,5 wt%. In this research, the objective was to investigate and optimize the technology for the waste stream received by ConocoPhillips as part of the Joint industry project. Furthermore, various oil contaminated drill cuttings from the Norwegian Continental Shelf were tested, in order to evaluate the technology for drilling waste on NCS. In addition to this laboratory research, the results were combined with accessible full-scale microwave treated data, in order to predict a realistic scaleup. The results of the optimized tests received from Eurofins were 0,51 wt% oil on cuttings (OOC) for ConocoPhillips 17-inch, 0,53 wt% OOC for ConocoPhillips 16X-inch, 0,44 wt% OOC for ConocoPhillips 16Y-inch and 0,07 wt% OOC for Equinor. These result was optimized with respect to energy consumption in relation to oil separation. The energy consumption for ConocoPhillips 17-inch was reduced by 23 % while achieving 0,51 wt% OOC. ConocoPhillips 16X-inch was reduced by 20 % in energy consumption while achieving 0,53 wt% OOC. ConocoPhillips 16Y-inch was reduced by 12 % in energy consumption while achieving 0,44 wt% OOC. Equinor was reduced by 16 % in energy consumption while achieving 0,07 wt% OOC. According to existing work found in the literature, a 35-50 % energy decrease for the cuttings is expected when treating the drill cuttings in full-scale. This relates to increased power density and a decrease in microwave frequency. By applying this to the laboratory results it leads to a technology that can reduce oil content to market leading levels, while simultaneously maintaining energy efficiency. Testing of ConocoPhillips 17-inch drill cuttings was done with a fellow student, Bernt-Helge Vedeld Nygård.

Master's thesis in Environmental technology A series of oil-contaminated sediment samples (drill cuttings) have been analyzed for their toxicity using in vitro bioassay based on fish cell lines. Drill cuttings are pieces of rock that come out of a well, (a deep hole made in the ground, to locate oil) when a well is drilled to an oil or gas reservoir. During drilling operations, a fluid known as drilling mud is used to lubricate the drill bit and carry the drill cuttings to the surface, where they are separated from the mud and cleaned. The mud is reused where possible, and the drill cuttings are either discharged or taken ashore for further treatment and disposal. Unfortunately, up until the mid-1990s, discharge of cuttings to the seabed was permitted in most countries. Therefore, they have formed piles on the seabed and also settled on and between some of the oil storage cells. The evaluation of the toxicity of the drill cuttings and in particular their potential adverse effects in marine organisms is of known importance. The present work focuses on the use of in vitro cell based bioassay to evaluate the ecotoxicity of drill cuttings. By using fish cell line (i.e., PLHC-1 and RTgill-W1), the quality of these sediment types were assessed through assays for general cytotoxicity, reactive oxygen species production (i.e., oxidative stress) and EROD activity (a PAH related metabolism enzyme). The obtained results were compared with data from natural fjord sediment samples. The cell viability, EROD activity, and ROS production showed an adverse effect to the oil-contaminated drill cutting for PLHC-1 in comparison to the natural fjord sediments. While RTgill-W1 showed an adverse effect in cell viability and ROS production for oil-contaminated drill cuttings in contrast to the natural fjord sediments.

An analysis of the flow and of the vertical transfer of the horizontal momentum induced by the breaking of modulated wave trains in wind and no-wind conditions is presented. The study is based on the results of two-dimensional numerical simulation of the Navier-Stokes equations for two-phase flow. The open source Gerris flow solver has been used, which employs a Volume of Fluid technique to capture the air-water interface. The breaking is induced through the Benjamin-Feir instability mechanism. The numerical simulations cover the entire range from the initial development of the instability, the breaking phase and the post-breaking evolution. In order to investigate the role played by the wind, a uniform wind profile, twice the phase speed, is initialized in the air phase and it is left to evolve while interacting with the wave system. Results in terms of averaged horizontal velocity and vertical flux of horizontal momentum are presented. It is shown that in the wind case the backward stresses induced at the wave troughs as a consequence of the flow separation at the crest influence significantly the flow in the upper water layer, particularly in the pre-breaking phase. No substantial differences are found between the wind and no-wind solutions in terms of the vertical transfer of horizontal momentum in the lower water layer. The vertical flux of horizontal momentum in air is consistent with the velocity reduction occurring in the wind case in the early stage.

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.

Master's thesis in Offshore Technology : Industrial asset management The Oil and Gas industry is the largest industry in Norway, making the supplying industry an important and profitable industry. Norwegian Offshore yards provide the oil and gas companies with products and services to develop, build, maintain and demolish offshore platforms, onshore plants, ships and other equipment. Competition is big between the offshore yards, and other countries’ providing cheaper products steals customers, making it important for the Norwegian yards to be innovative and upgrade their companies to make them more competitive. With all the globalization that has occurred the competition has gotten even harder, and an unstable Oil price resulting in an unsecure market for the offshore industry, the pressure and expectations are even higher for the Norwegian Offshore yard to deliver. A huge part of being innovative in the industry of pre-fabrication is to implement and use new technologies. These technologies help to reduce the delivery time, make the production more efficient, reduce the costs and increase the quality. The purpose of this thesis is to identify and evaluate the potential for using new technologies at Norwegian Offshore Yards, helping them to stay innovative, be able to compete with foreign yards, and maintain the industry inside Norway. Some of the technologies that have emerged after research for the thesis, and potentially can be implemented is digitalisation, by using cloud storage and cloud computing, sensorization with use of smart sensors, measuring real-time data, autonomization by making the machines and equipment automated and start using robots, and connectivity, connecting all the machines, devices and sensors together through internet in combination with AI. All of this combined has the potential to in the future result in a fully automated pre-fabrication, with no human interference, only human supervision.

Master's thesis in Environmental Technology The purpose of this study was to quantify the environmental footprint of discharge to sea from a producing subsea installation and its semi-submersible host platform in the North Sea. Portion of environmental burden that could be allocated to each installation was identified. Having no physical discharge point, specific portion produced water and waste generated from subsea installations have not previously been studied. Main concepts and methodology of the established life cycle assessment was followed through life cycle thinking using real data for best estimation of the posed risk and impact. Dose-response risk and assessment model was implemented as currently the best available tool for impact assessment of the complex mixture the discharge is composed of. All sources of discharge during the production phase were identified and assessed, and DREAM results evaluated the subsea contribution to risk by the discharge. A more comprehensive evaluation of all phases of the life cycle including more impact factors is needed to properly evaluate the total environmental footprint by a subsea installation.

Master's thesis in Environmental Technology Pipelines are an essential part of the oil ang gas industry as they are the main means of transportation. As the offshore technology advances, subsea pipelines are being operated in more demanding environments. In field operations where corrosion occur, chemicals called inhibitors can be employed. Corrosion inhibitors (CI) are injected in small amounts with low concentrations to ensure flow assurance and controlling corrosion, especially CO2 corrosion. Currently there are no CIs that functions at elevated temperatures, so the purpose of this master thesis was to synthesize CIs for that purpose. The master thesis was divided into two projects, one screening process to see whether or not it was possible to synthesize CIs below 100, and if the presence of a catalyst would help. The second project was a small experimental design project where three aldehydes and three catalysts was used in different combinations. The goal was to achieve a six-membered ring in these CIs as the theory says that this is crucial for the performance. Two kinds of test were performed to evaluate the chemical performance of the synthesized products; High pressure, high temperature (HPHT), static autoclave testing and kettle-testing. The HPHT Autoclave tests were executed at Schlumberger in Aberdeen. Kettle-testing was done using the Linear Polarization Resistance (LPR) technique. Time (hours) and Corrosion rate (mils per year) were the parameters which were compared among the tests to reveal the best corrosion inhibitor. To characterize the synthesized products infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) was performed. NMR spectra of the products related to structure III show that these compounds do not have the six-membered ring which was the goal for the synthesis. HPHT, static autoclave tests revealed that these products do not perform well as expected considering the NMR results. The same is shown in the Kettle-test where product 24 does not perform well as a CI, with the best inhibition efficiency of 37.7%. Product 12 on the other hand show mixed results, but product 12 injected with formulation with 1% 2-mercaptoethanol (2-ME) tested in a cell with 80% NaCl (3%) brine and 20% kerosene have a performance of 93.6 % efficiency inhibition. There were also some other interesting results from the HPHT, static autoclave test. Product 6 with an average performance of 7.205 mpy, with half the amount of active product in the formulation injected. Further research after this thesis could be on dose response (in context of the HPHT static autoclave test) to find the cut off points in performance in terms of corrosion rate and surface conditions. Further characterization of the products related to structure III is also work that should be done in order to characterize the actual product. It would also be smart to optimize the synthesis ratios and order of executing synthesis steps in order to optimize costs related to the final product(s). Additional testing of the products at Schlumberger (Forus) with Rotating Cylinder Electrode (RCE) is also of interest as this test add medium stress-shear.

Master's thesis in Environmental Technology As urbanized areas grow in scale, the negative impact on urban surface runoff increases. This fact creates the urge to take proper measures to control and prevent the downside effects of urbanization on natural water resources. This study analyzed the water quality of Madlabekken stream and Madlabekken constructed wetland. The main focus of this work is to evaluate whether the inlet to the wetland is urban area runoff, or if it contains periodic household wastewater contributions. In addition, estimating the wetland’s efficiency is the secondary objective. Weekly samplings were collected from January to May 2018 continuously, and some grab samplings were done before this period between October to December 2017. Evaluation of water quality parameters including TSS, CODt, CODs, TP, PO4-3, TN and NH4+ at both inlet and outlet of the wetland was achieved by performing weekly analyses of water samples. The overall results showed that the quality of water is in range of urban storm runoff and in some cases much lower. The analyzed samples did not show a trace of wastewater and sewage. The highest concentrations were observed in February due to temperatures below zero which caused low levels of water in channels. Also, due to low concentrations, this constructed wetland did not show high efficiency in removing pollutants. Nevertheless, generally removal efficiency found to increase in the higher concentration of TSS and nutrients, and it was close to similar CWs removal efficiency in higher concentrations. TSS was reduced by 46%, and the reduction percentage for CODt and CODs was 22% and 6% respectively. For TP and PO4-3, in average the reduction is approx. 25% and 5% respectively. For TN and NH4+, considering the removal efficiency variation in different months, on average no reduction was found from influent to effluent. Ultimately, comparing to similarly CWs, this wetland has a lower removal efficiency.

Master's thesis in Environmental technology Subsea tie-in fields on the Norwegian continental shelf (NCS) appear to have extremely low greenhouse gas intensity based on available environmental data, as emissions related to offshore oil and gas processing is reported from the host platform. The goal of this thesis was to quantify the environmental footprint of the subsea field Vega with respect of emission to air. The work was simplified by using carbon footprint as a single-issue method. A carbon footprint should, according to ISO 14067, be quantified by greenhouse gas (GHG) emissions and removals over the life cycle of a product. The methodological framework described by the international organization for standardization was adapted to this study by applying a bottom-up approach for data collection and inventory modelling. A case study was included to illustrate an example of how the inventory model can be used. Results: The carbon footprint (total GHG emissions) and GHG intensity of Vega were estimated as 0,290 million tons CO2-eq. and 0,411 kg CO2-eq./GJ respectively for 2010-2017. Discussion around the inventory results is focused on GHG intensity rather than total GHG emission (i.e. carbon footprint). This was to reflect the Norwegian Environmental Agency’s goal to both reduce greenhouse gas emission and increase production of hydrocarbons on the Norwegian continental shelf. Conclusion: Applying a life cycle inventory approach drastically changed the emission profile of Vega, compared to the current reporting practice. However, as this project represent the very early stage of implementing life cycle thinking in Wintershall, the principles of the life cycle inventory are more important than the inventory results itself. Further implementation of life cycle assessment within Wintershall should be based on the intended use and goals set by the company.

Master's thesis in Offshore technology: Industrial asset management The technological advances have and are continuing to develop at an accelerating pace. One may argue that the speed has reached a limit that companies struggle to follow, something that may endanger their business model. The technological breakthroughs are announced so frequently, that a new need has emerged: a method for companies to identify how the rapid technological developments can benefit their business. A model that assesses the technologies against their business segments and facilitates the identification of opportunities is thus necessary. This research undertakes this challenge and applies such a model to the industry. A suitable area to carry out this task is the offshore wind industry. The demand for sustainable power is continuously increasing, and the offshore wind industry has proved to be a highly promising solution when the massive challenge of decarbonizing the energy industry. This industry is strikingly fragmented, with few established procedures, especially within operations & maintenance (O&M). Furthermore, operational costs have to be driven down dramatically in order to prove its viability. The area of O&M is then an appropriate area for applying the model. The aim of this thesis is thus to identify and evaluate technological innovation opportunities in the O&M segment of offshore wind. The model has five steps: 1) Breakdown of the industry and technology trends 2) application of technology trends to the industry segments, 3) identification of opportunities, 4) presentation and evaluation of opportunities, 5) presentation of the most promising opportunities through a business model canvas (BMC). The industry breakdown and the theory regarding technology trends (chapter 3 and 4) provides the theoretical introduction needed in order to digest the following chapters. Chapter 5 propose 14 innovative opportunities, which is immediately screened. Chapter 6 presents three of the most promising opportunities in the BMC. The offshore wind industry is characterized by harsh conditions and remote areas. This makes some technologies more suitable than others, and will thus be focused on in this research. Technologies that has proved to be particularly promising are MEMS sensors, Fiber Bragg gratings, LiDARs, AUVs, crawlers, drones, digital twins, distributed ledger technology, smart glasses, virtual reality and Big Data. The most promising opportunities that are identified in this research are: A method for monitoring scour with fiber optic sensors, a digital twin for data- and documentation control, and a method for remote maintenance support using smart glasses.

Master's thesis in Offshore Technology : Marine and subsea technology If one could imagine a single pipeline spanning approximately 11,000 km from Oslo, Norway to Bangkok, Thailand, this would be similar to the total length of the Norwegian oil and gas pipeline network combined [1]. The hydrocarbon resources located in the cold waters of subsea fields offshore Norway, are transported via pipelines to either an onshore processing facility or directly exported to consumers in the UK and European Union area. Long sections of this transportation pipeline network require protection from potential hazards, such as trawling-shipping activities and dropped objects. One common method of pipeline protection is the installation of concrete mattresses on top of the pipeline. Concrete mattresses are also utilized where soil stabilization and foundation support is needed. Despite a large number of concrete mattress installation projects is performed annually, the current deployment method is relatively inefficient, as each mattress is individually lifted and installed. The present thesis proposes a handling mechanism for the deployment of multiple concrete mattresses in a single lift. Initially, Subsea 7 proposed a concept for a multi-installation tool. The concept comprised a steel frame that would facilitate six concrete mattresses and embody a handling mechanism with rotating pipes and gears. The mattresses will be lowered to the seabed through the mechanism with the assistance of a ROV torque tool. The key feature of the project is the study of the handling mechanism, and more specifically, to resolve the concept under certain requirements, elaborate on its operational and installation aspects, and assess the structural integrity of the finalized solution. The initial concept is thoroughly presented and examined. The operational procedure and the functionality of each component is also discussed. The design phase starts with the dimensioning of the rotating parts of the mechanism, which yield the required design values of the gearset. In the sequel, an arrangement of spur gears is designed according to the limitations that have been set. The strength of the gearset is evaluated with the use of analytical solutions. Additionally, a finite element analysis of the response of the gearset is performed for verification and comparison purposes. Finally, the current thesis work concludes to a new configuration of the handling mechanism with the use of alternative ROV tooling aids. The design of the new setup is presented and the structural integrity of the new components is assessed. Lastly, some recommendations for future work are given.

Master's thesis in Environmental technology This study describes anaerobic co-digestion of aquaculture waste from Fister Smolt and municipal waste from IVAR SNJ. Both waste types are in rapid increase worldwide, yet production of biogas has mainly considered municipal waste as substrate thus far. There is a knowledge gap in the current understanding of co-digestion of aquaculture and municipal waste, and research and development are required. The main objective of this study was to evaluate the biogas production potential and the stability of this co-digestion process. The biogas production potential and methane yield were assessed in anaerobic batch tests using the AMPTS II system. Produced methane corresponded to the amount of COD entering the batch test system, and around 70% COD of the aquaculture waste from Fister Smolt and the primary sludge from IVAR SNJ was converted to methane. Results from the batch tests showed a 1% increase in methane yield when aquaculture waste and activated sludge from IVAR SNJ was co-digested. However, this value was regarded as too low to confirm an actual increase in methane yield. No increase in methane yield was observed when aquaculture and municipal waste was co-digested. Results from the daily fed stirred tank reactor showed a 6% increase in methane yield when aquaculture and municipal waste was co-digested. However, this value was also regarded as too low to confirm an actual increase in methane yield. The process stability and performance were evaluated using daily fed stirred tank reactors. Four different reactors were set up with a SRT of 15 days. The primary sludge reactor and the co- digestion reactor experienced no inhibition. The aquaculture waste reactor experienced ammonia induced inhibition with an ammonia concentration of 50 mg/l, at a pH of 7.3 and an ammonium concentration of 1.6 g/l. An inhibited steady state was assumed when an increase in VFA concentration to 2100 mg/l reduced the ammonia concentration to 30 mg/l, as the pH was decreased. Methane was produced at a satisfying level. The pH adjusted aquaculture waste reactor on the other hand did not reach ammonia levels that were high enough to inhibit the performance of the reactor, and a more stable process was achieved. It is possible to anaerobically digest aquaculture waste from Fister Smolt without adjustment of pH or co-digestion with primary sludge. However, nitrogen concentrations need to be closely monitored to avoid accumulation of ammonia.

Master's thesis in Offshore technology : Marine and subsea technology In the past decades, the global wind energy has rapidly grown. Greater potential of wind recourses is explored in the deeper sea; hence, wind farms have progressively moved toward the deep water over the years. Floating wind turbines then become an available solution which could be widely applied to deep water. Spar, semi-submersible and tension-leg platform (TLP) are the main types of floating substructure for supporting the wind turbine. The wind turbine can be generally categorized into horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) in terms of the direction of the rotating axis. Compared to floating HAWTs, floating VAWTs have several advantages such as lower maintenance and operational costs etc. The deployment of floating VAWTs starts to arouse people’s attention. Recently, the applications of floating VAWTs in deep water have been studied by several researchers. However, the feasibility of deploying a floating VAWT at a moderate water depth has not yet been discussed. In addition, offshore wind energy is not the only source to produce power in a marine environment. Wave energy exists huge potential to be utilized. The combined concept that can harvest both wind and wave resources becomes another alternative solution, which could lower the cost and increase the power efficiency. Several concepts of the integrated system which combines a floating HAWT and a wave energy converter (WEC) have been proposed and discussed, such as a semi-submersible HAWT with the flap-type WEC, a combination of spar-type HAWT and a torus-shape WEC, etc. Considering the advantages of the floating VAWT, an integration of the WEC and the floating VAWT deserves a further investigation and evaluation. This study is inspired by the merits of the floating VAWT and the successful experience of the Hywind project in Scotland. The thesis aims to investigate and assess the feasibility of the spar-type VAWT in multi-applications. A short spar VAWT at moderate water depth and a combined torus-shape wave energy converter and spar-type VAWT concept (STC VAWT) in deep water are studied under operational conditions. Both concepts are compared with a spar-type VAWT in deep water to evaluate its advantages and disadvantages. In the first concept, a short spar VAWT supporting a 5 MW Darrieus rotor at moderate water depth is proposed by following the deep spar concept in deep water. This feasibility is thoroughly addressed by comparing the dynamic responses of spar-type VAWTs in deep water and moderate water depth. A fully coupled simulation tool, SIMO-RIFLEX-DMS code, is utilized to carry out time domain simulations under turbulent wind and irregular waves. Dynamic responses of the short spar and deep spar VAWTs are analyzed and compared, including the natural periods, wind turbine performance, platform motions, tower base bending moments, and tension of mooring lines. The statistical characteristics of the thrust and power production for both spars are similar. The comparison of platform motions and tower base bending moments demonstrate a good agreement for both spars, but the short spar has better performance in surge/sway motions and side–side bending moments. The 2P response dominates the bending moment spectra for both spars. A significant variation in tension of Mooring Line 1 and a larger corresponding spectrum value are found in the short spar concept. The results indicate that the application of short spar VAWTs is feasible and could become an alternative concept at moderate water depth. An integration of spar-type VAWT and a torus-shape wave energy converter (STC VAWT) is considered in the second concept. This combined concept utilizes the relative heave motion between the torus and the spar buoy to harvest the wave energy. An integrated aero-hydro-servo-elastic tool (SIMO-RIFLEX-DMS code) is used to study the power performance and the dynamic response of the STC VAWT under operational conditions with the combinations of turbulent wind and irregular wave. The strength and weakness of the second concept are explored in comparison with the spar-type VAWT. The WEC can provide additional power and increase the total amount of production in the combined concept. The 2P loadings of the STC VAWT show a good agreement with the spar-type VAWT. The additional torus is exposed to lager wave excitation force, which leads to significant variations of hydrodynamic loads on the STC. The torus acts as a damper at the mean sea level, which could mitigate the variation of the floater motion in surge/sway/pitch. The heave natural period of the STC system is in the same range with ocean wave periods. A larger heave response may be excited during operation, whereas it is beneficial for wave energy absorption. The statistical result indicates that the STC gives larger standard deviations of tower base bending moments than the spar-type VAWT, which is due to the torus effect. The larger variations of the tension of Mooring 1, which is aligned with the wind and waves, are also observed in the combined concept. Overall, the STC VAWT is applicable in the operational stage, and a further study on the current condition or extreme environments is recommended in the future.

Master's thesis in Offshore technology: Marine and subsea technology Sea of Okhotsk is characterized by harsh environmental conditions. The navigation period lasts approximately 5 months (June – October). Sea ice starts to form in November with 0.8-1.1 m thickness. Vessel icing is possible from October. Note that there are many oil and gas fields in the Sakhalin offshore which means that marine installation operations should be performed. The area with possible subsea field developments will be considered in this project (Yuzhno-Kirinskoye field). The focus is on environmental conditions analysis (icing and sea description) as these are the most important for marine operations. We are not expected to carry out such operations when there is drifting sea ice. Kirinskoye field subsea manifold installation example will be introduced to define some parameters for subsea manifold (mass, dimensions). Basing on manifold parameters a vessel for lifting operations will be chosen. Calculations and analysis are based on the parameters of a particular typical vessel. Some discussions about lifting operations and environmental conditions standards (DNV) will be added. The weather window estimation process will be shown in this report. A probabilistic approach with Monte Carlo simulation will be used in calculations. It is important to know the probability of exceeding the operational limiting criteria value of wave height and icing rate. In the report relevant theory is included to perform calculations.

Master's thesis in Offshore Technology : Industrial Asset Management Industry 4.0 is among related terms a buzzword in today’s industry. It is clear that several technologies aim to enable operators to obtain better control of their production operations, avoid non/added value events e.g. failures, stoppages, cut the operating and maintenance cost, and extend the asset lifetime. All these benefits are achieved by collecting and analyzing data in a smart i.e. automated manner. However, there are four main challenges to achieve such transformation (lack of standards, work processes, product availability and new business models). Therefore, industrial companies as organizations are struggling to navigate through the hype of Industry 4.0 to make digitalisation initiatives successful and beneficial for their purposes. This thesis is in line with the above addressed challenge where it tries to answer the following research question: “How can a predictive maintenance programme be developed and implemented in fish feed processing industry in a cost-effective manner that complies with the Industry 4.0 vision”. Thus, the purpose of this thesis is to propose and demonstrate a model i.e. set of procedures to develop predictive maintenance programmes that are compatible to the needs of the fish feed processing industry and their organizational resources. Moreover, the developed model shall be compliant to Industry 4.0 vision. In order to achieve such purpose, the developed model is demonstrated at two levels i.e. machine and organizational level through a purposefully selected case study. The selected industrial case study is related to the extruder as one of the most critical equipment in Skretting’s production plant (Hillevåg Plant). This thesis, based on the case study, proposes a model to develop and implement predictive maintenance programmes through four phases; systems analysis of the physical assets, programme development based on Industry 4.0 architecture, cost-benefit analysis, and roadmap development for programme implementation at organizational level. The systems analysis is a core phase to develop an intelligent system with a purpose (develop smart asset and operations to the required level and not over/implementation to just follow the buzzword hype or wave). Systems analysis was an effective methodology to identify the critical assets that have priority to be transformed into smarter state to gain the potential benefits of the enabling technologies of Industry 4.0. The systems analysis highlights that the wear and fatigue crack faults are the most critical failure causes within the selected critical system i.e. the extruder. The wear fault can be monitored by detecting the natural frequency shift as the main fault symptom, and the fatigue fault can be monitored by detecting the amplitude values at the crack frequency as a main fault symptom. The development model illustrates how the proposed seven layers (from data into decision) can be used to allocate the technical requirements needed to build the predictive health monitoring system in an effective and traceable manner. It clarifies the requirements of the system for each layer which is useful to compare against service provider solutions. The cost benefit analysis shows that the cost of implementing and running the proposed predictive health monitoring system for ten years is lower than the value gained by the potential mitigation of the several failure events related to the two faults from the optimal baseline maintenance schedule. The implementation model at organizational level concludes that five steps are required to successfully implement a PdM strategy that complies with Industry 4.0 vision. The five steps are self/assessment, strategy development, roadmap creation, capability and competence building and finally take action i.e. piloting the change.

Master's thesis in Offshore technology The Northern Caspian Sea is considered to be a very perspective region for oil and gas production growth. However, the challenges encountered in the Northern Caspian Sea are not usually met in such combination in another regions, so this imposes special requirements for the further development of hydrocarbon fields in the region. This thesis is focused on the field development in the Kazakh sector of the Northern Caspian Sea and it is addressed to a discussion of artificial island concept that might be applied for these conditions. Possible options for production of hydrocarbons, oil and gas transportation and processing are discussed on basis of the analysis of existing solutions for similar conditions. Attention is also given to the ice load mitigation measures and other aspects that should be taken into consideration during the development of fields in the Northern Caspian Sea. In near shore oilfield development of The Caspian Sea, artificial island is the better method because of the economic and technical convenience. But compared with the traditional way of reclaiming land from beaches, the construction of artificial island should be given with more attention to the ocean hydrological and dynamic changes, the mutual implication between engineering zone and marine environment. Finally, conclusions wrap up the thesis in order to summarize the acquired findings.

Master's thesis in Offshore technology: Marine and Subsea Technology Sufficient still water airgap is important both for fixed and floating platforms. What is a sufficient airgap according to the rules depends on the rule regime under which the platform is designed. All fixed platforms and floating platforms operating at one site for its design life time, platform design will follow the regulations provided by the Petroleum Safety Authority Norway. For floating platforms operating as drilling rigs, there is an opening in the regulations to design platform according to the maritime regulation. In this master thesis we will focus on a semi-submersible platform. The aim is to identify a proper set of design sea states for the platform regarding airgap assessment. We assume the platform to be operating in the Northern North Sea. NORA10 data for the years from 1957 to 2017 will be made available for the project. Transfer functions for the global motions of the platform are also available. Airgap values will be presented. Aker Solutions

Master's thesis in Offshore technology : subsea technology Since the 1950s, risers have continued to be an important part of an oil and gas producing field. As the primary equipment that conveys fluids to and from the topside vessel, it is important that a riser is designed to withstand all conditions it will be subjected to during its lifetime. With hydrocarbon exploration activities moving into ultra-deep water, research related to the structural integrity of a riser deployed in ultra-deep water has become necessary. The ultra-deep water region considered in this thesis work is the Santos Basin located about 300 km offshore Brazil. The Santos Basin is a benign environment that is not characterized by hurricanes, typhoons or extreme weather conditions. However, oil producing activities in this region would require a vessel that has storage capabilities due to the distance the region is from shore. With this requirement in mind, different floaters were evaluated and a spread-moored Floating Production, Storage and Offloading (FPSO) vessel was selected for this thesis work. The selection of the spread-moored FPSO presented a new challenge; high motion sensitivity. Since FPSOs are high motion vessels, risers connected to them will experience fatigue damage in their touchdown zone. However, after evaluation of different riser concepts, the Steel Lazy Wave Riser (SLWR) was selected because it has the ability to decouple its touchdown zone from vessel motions due to the presence of buoyancy modules fitted along the lower section of the riser. With the selection of spread-moored FPSO and a SLWR, material selection for the SLWR was carried out. For ultra-deep water deployment, a riser’s material should posses ultra-high strength, good weldability, high collapse resistance, high operating pressure and excellent low-temperature toughness. These material properties are found in the API 5L X65,X80 and X90 carbon steel grade material. Hence, they were the selected material used for the SLWRs in this thesis work. Dynamic and fatigue response analysis was conducted on the SLWRs made of each material and it was observed that all the three materials met the requirements of the DNV-OS-F201 reference standard with the X65 riser having the worst dynamic response, followed by the X80 riser, followed by the X90 riser. Also in past SLWR deployments with spread-moored FPSOs, risers were usually connected to hang-off points along the port side of the vessel. In this thesis work the SLWRs were connected to hang-off points both along the port side of the vessel and along the middle of the vessel. The purpose of doing this was to investigate if buoyancy can be saved by connecting a riser along the middle of the vessel rather than the along the port side. From the results of the investigation, it was observed that about 7.5% of buoyancy could be saved by connecting a riser to the middle of the vessel rather than to the port side of the vessel. In addition, it was observed that risers connected to the middle of the vessel showed an increase of at least 246% in the minimum fatigue life observed. Overall, all the riser materials considered in this study all meet the dynamic and fatigue response criteria. Therefore, further work should be carried out as given in the recommendations of this thesis work to select the most suitable material for deployment in the ultra-deep water region of the Santos Basin, offshore Brazil.

Master's thesis in Environmental technology The purpose of this thesis is to develop models to determine the effectiveness of oil spill response systems in Arctic environment and to evaluate their impact on the ecosystems. Three response systems are investigated: mechanical recovery, in situ burning, and chemical dispersion. With the increase in petroleum activities in the Arctic, it is important that companies gain the knowledge needed to exploit the resources in a sustainable manner. What works well in one place will not necessarily have the same effectiveness in other places. This is precisely why it is important to understand the factors that determines the effectiveness of the response and the degree of environmental impact in the Arctic. The thesis includes a case study of a simulated oil spill from the Johan Castberg field, located in the Barents Sea. The developed models are used to determine the potential volumetric reduction of an oil slick. The application of the models in a case study helps to point out the main factors affecting the effectiveness of the response systems in the Arctic. Among all the identified factors, response time, wind and water-in-oil emulsion rate seem to be the determining factors. Oil slick thickness is identified as the major source of uncertainty in the existing models. Based on the expected response time and the oil properties of the studied oil types in the Arctic, mechanical recovery seems like the best response option.

Master's thesis in Offshore Technology: Marine and subsea technology As the demands for installation at deeper waters is increased, technology for such installations must be adapted to the conditions of the deep and ultra-deep water depths. This thesis provides information of such installations methods, including non-conventional installations methods. The main focus of the thesis is using fibre rope deployment system to deploy equipment at water depths up to 4000 m. The use of fibre rope instead of the traditional steel wire is popular due to the similar specific gravity to water, which makes the fibre rope naturally buoyant in water. This cancels the self-weight problem of the steel wire as hoist line. Due to the different properties of the fibre rope, a new and cutting-edge technology was developed by the industry for deployment using fibre rope. To investigate the possibilities of deploying equipment to water depths of 4000m, numerous simulations were conducted using the simulation program the SIMO. The results of the simulations show no significant problems using fibre rope to deploy various common subsea equipment. However, the positioning of the equipment is demonstrated to be a major challenge at these

Master's thesis in Offshore Technology: Marine and Subsea Technology Thrusters are vital for the functionalities of remotely operated vehicles (ROVs). The development of thruster design is a trade-off between cost, thrust force, physical weight and size. Furthermore, it is known that problems with thrusters are a common fault in ROVs. As a result, this study is performed on different thruster configurations to highlight important aspects in the design of thruster systems. This includes the analysis of different marine propellers with 4 to 6 blades and with a diameter of 300 to 400 mm. A six degree of freedom model is created in OpenModelica to investigate vibrations and bearing responses in thruster systems. The model consists of a marine propeller, a shaft, and two bearings, and is applicable for simulating various steady-state cases. The results of the simulations return displacements in the axial, horizontal, and vertical directions, which are further used to investigate vibration amplitudes and bearing life. The marine propeller contributions to the OpenModelica model are based on propellers from the Wageningen B-screw propeller series and open water tests of this series. The hydrodynamic added mass and damping elements are calculated from different sets of regression equations depending on the number of blades on the propeller, blade area ratio, and pitch ratio. Meanwhile, the mean thrust and torque are obtained from open water test data of the relevant propeller. The mean thrust and torque are then further used to calculate the dynamic forces and moments from the marine propeller. The bearing life of the bearings in the thruster is highly dependent on the axial load acting on the bearing, i.e., the thrust force. Moreover, if the propeller is not balanced then high centrifugal forces can occur, resulting in severe forces in the radial direction that can be of concern regarding the bearing life. Furthermore, the thruster and bearing design should be related to the maximum thrust force desired from the thruster. It is possible to use different propellers with the same design, to change the RPM-thrust force configuration, or to change the vibratory properties of the thruster system. However, the maximum thrust force for which the original thruster was designed should not be exceeded. Furthermore, the vibrations in the thruster system depend on the bearing configuration, stiffness, unbalance, and the propeller type.