Day 4 Thu, May 09, 2019最新文献

{"title":"Wave Energy Converter Arrays: Optimizing Power Production While Minimizing Environmental Effects","authors":"K. Raghukumar, S. McWilliams, G. Chang, Jesse D. Roberts, Craig Jones","doi":"10.4043/29658-MS","DOIUrl":"https://doi.org/10.4043/29658-MS","url":null,"abstract":"\u0000 The nascent marine renewable energy (MRE) industry requires robust tools to maximize power output while evaluating the potential environmental effects of marine hydrokinetic (MHK) devices. Wave energy converter (WEC) devices in particular, are in early stages of development and may deploy a wide range of technologies to harness wave energy. The technical activities and processes used to assess WEC arrays for both power production and environmental effects requires streamlining to lower the levelized cost of wave energy projects and facilitate timely, cost-effective environmental review and compliance. A robust approach using numerical models to simulate the WEC devices and array layouts is presented that simultaneously evaluates power production and assesses environmental effects. \"WEC-friendly\" open-source numerical tools have been developed that are capable of assessing the environmental force on and potential changes to the environment caused by the energy extraction by WEC arrays. A case study is presented to demonstrate how the changes in WEC array configurations can be mapped and quantified using a validated model. A discussion of how changes in WEC devices and array configurations are developed to provide critical information on both engineering and environmental risk. This allows for optimization of WEC deployments to maximize power capture while minimizing environmental impacts.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133452800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The True Value of Integration","authors":"Alexander Mackay, N. Rodriguez, M. Stenhaug, Johny Samaan","doi":"10.4043/29625-MS","DOIUrl":"https://doi.org/10.4043/29625-MS","url":null,"abstract":"\u0000 Field development is a complicated process involving a multitude of disciplines, technologies and workflows. The typical approach to field development is long, fragmented and costly. This is due to set process and work flows with limited flexibility, inefficient tools and transfer of information, uncertainty of required scope for each phase and the management of multiple contractors.\u0000 An example of this is a stage gate process, where regardless of the size of the prospect the same set work tasks and deliverables are required to pass to the next phase, generally no assurance is performed upfront to determine the actual requirements. Another example is field development tools, which are used in isolation from reservoir simulation to flow assurance/facilities design with limited integration, which leads to the inefficient transfer of data and a reduction in accuracy.\u0000 The above causes unnecessarily long schedules, repetition in scope and results in sub-optimal technical solution and project economics. The requirement to transfer and interpret information between multiple parties and stages (internal and external) creates unnecessary complexity and introduces additional risk to the final technical solution.\u0000 This paper will demonstrate the value of an Integrated Field Development approach for a large Deepwater gas condensate development offshore Australia, and how this approach can dramatically reduce duration, improve accuracy, lower contingency and maximize the economics of a project. It shows the clear advantages of facilities engineers working closely with subsurface, drilling and completions and will highlight some of the key features that make the Integrated Field Development approach a success.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"410 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124363645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solving the Operational Challenges of Sulfate Removal Units Using High-Flux, Fouling-Resistant Nanofiltration Membranes","authors":"T. Krebs, R. Ganguli, G. Lage, P. Verbeek, V. Mehrotra, P. Florido, M. R. Akdim","doi":"10.4043/29532-MS","DOIUrl":"https://doi.org/10.4043/29532-MS","url":null,"abstract":"\u0000 Desulfation of seawater before injection is required to control reservoir souring and scale formation. For this task, operators use nanofiltration (NF) membranes in sulfate removal units (SRUs). The tendency of the membranes to foul is a key operational challenge. To overcome fouling, frequent chemical cleaning is required. An additional constraint for SRUs is that the amount of treated water cannot be increased easily as a higher water output results in an even faster fouling of membranes.\u0000 In this paper, we describe a method to enhance permeate flux and fouling resistance of desulfation membranes. The enhancements are achieved by modifying the active layer of commercially available NF membranes using a permanent coating that increases hydrophilicity while retaining the high surface charge characteristic of NF membranes.\u0000 We report the results of a six-month field trial with the coated membranes. The test was executed at the Seawater Desalination Test Facility in Port Hueneme, California using 2.5\" dia. membrane modules. The test skid contained two different parallel flow lines with a stack of six coated 2.5\" dia. membranes in series, and an uncoated 2.5\" membrane for reference.\u0000 The results show a 25% higher permeate flux for the coated membranes compared to the uncoated membrane at the same transmembrane pressure. Sulfate rejection was unchanged for both coated and uncoated membranes during the entire duration of the test. The coated membrane also showed a lower fouling rate than the uncoated membrane. The time between cleaning events increased by ∼ 38 % for the coated membranes as compared to the uncoated membrane, and the coated membrane processed ∼ 63 % more permeate before cleaning was required. Preliminary results also indicate an enhanced chlorine tolerance of the coated membranes of at least 3000 ppm-h under continuous chlorination at ∼ 1 ppm.\u0000 The impact of the coating on the economics of SRU operations will be discussed in the paper. The results presented in this paper demonstrate that performance and operability of SRUs can be significantly enhanced by a newly-developed coating, and that a significant reduction in the lifecycle cost of SRUs can be achieved.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128472336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FTMC Turbine: A Marine Turbine for the Gulf Stream Current Off the Coast of Florida","authors":"J. Moreu, Robert Barrett, Ricardo García-Morato, R. Dragan, Eduardo Aguado, G. Cooke","doi":"10.4043/29629-MS","DOIUrl":"https://doi.org/10.4043/29629-MS","url":null,"abstract":"\u0000 This paper describes a marine turbine concept specifically designed to harness the energy from the Gulf Stream Current. This current achieves, at some points off the East coast of Florida, a speed that ranges between 2 and 4 knots in the first 100m of water depth, for 85% of the time. A device in this region shall be at least 40m deep to avoid navigation and wave interference. Since in these fast regions the seabed is 200 to 500m deep, moored solutions are the most feasible option.\u0000 Moored turbines require buoyancy to allow the device to be located at the optimal depth quite easily. In our design the buoyancy is given by a nozzle, which does not obstruct the flow but accelerates it. Consequently the blade size is reduced and protected from shock.\u0000 The mooring consists of a tension-tether arrangement that significantly reduces the vertical displacements, minimizing the pressure variation in the air tanks. This tension-tethered mooring also reduces the footprint and can be arranged to allow the turbine to passively turn into the current direction, increasing the capacity factor. The device is installed by controlling the nozzle ballast water and air pressure, and by attaching the mooring line to a concrete block on the seabed. If maintenance is needed the operation can be reversed, helping to reduce OPEX.\u0000 The combination of a TLP (tension leg platform)-like mooring and a robust floater arranged as a nozzle makes the concept feasible. A magnetically-geared Pseudo Direct Drive (PDD®) generator ensures a robust, direct-drive, high torque, low speed and highly efficient solution that can operate in the inherently rough immersed conditions.\u0000 The design has been validated in 2018 through prototype testing at INTA-CEHIPAR model basin in Spain. Thus, the concept as an offshore alternative energy converter has been confirmed. The small-scale demonstrator is designed for 600 Nm and 6 kW, with rotational speeds of up to 100 rpm. During the tests, the generated power has been measured at different generator and current speeds with the device fixed. The levels of generated power and efficiency agree with the CFD calculations. Furthermore, the stability of the marine turbine has also been confirmed. Several configurations of mooring lines and stabilizers have been tested to ensure that not only the unit is self-steerable, but that it also minimizes Vortex-Induced Motions.\u0000 Regarding the business case, competitive values of the levelized cost of energy (LCOE) can be achieved because of the high power density available in the selected coastal locations combined with high capacity factors. This overcomes the higher capital expenditure (CAPEX) per MW of each unit, because it is fully immersed, compared to offshore wind solutions.\u0000 The project has been co-financed by the Eurostars Program.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126757857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Main Factors Impacting Oil Projects Return: A Sensitivity Analysis","authors":"R. Lucchesi","doi":"10.4043/29594-MS","DOIUrl":"https://doi.org/10.4043/29594-MS","url":null,"abstract":"\u0000 Performing robust economic valuation is critical to ensure success on oil development projects. In a dynamic market with ever changing variables, risks and uncertainties must be well analyzed and mitigated to prevent less than expected economic returns in mega-projects such as an offshore deep-water oil field development. This study aims to evaluate what are the most important factors that should be considered when assessing risks in a project economic valuation, using Brazil’s Production Sharing Contract (PSC) fiscal system as an example. A sensitivity analysis was performed in a standard offshore oil production project using the discounted cash flow method. First, a base scenario was calculated, and then, four key assumptions were chosen to be tested – oil prices, capital expenses (capex), operational expenses (opex) and recoverable reserves - and changes of + and - 20% in each, one at a time, were applied to the base scenario, and their impact on the internal rate of return and government take were measured. Findings indicate that, at least in the Brazilian PSC case, oil price is the most influential parameter in the project profitability, presenting an almost perfect positive correlation with the rate of return. Oil price is also the most difficult assumption to project and the one that is completely out of companies’ control, which poses them a significant challenge, to be able to keep its projects economical under volatile prices. Main investment decision gates happen years before first oil is produced, so the level of uncertainty on this parameter is very high. This study reinforces the concept that a good oil price forecast is paramount in projects valuation. Additionally, companies should always make investment decisions based on multiple oil price scenarios to determine the project’s financial risk.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129248144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metocean Decision Making Lessons-Learned during an Oil & Gas Construction Project Conducted in a Harsh Coastal Environment","authors":"T. Bullock, S. Beale, Ron McCarthy, Hugh Anthony Kelly","doi":"10.4043/29422-MS","DOIUrl":"https://doi.org/10.4043/29422-MS","url":null,"abstract":"\u0000 The Hebron Platform was constructed from 2012 to 2017 in the harsh environment of coastal Newfoundland and Labrador. The construction site experienced winds and seas that approached expected values for a 100-year return period event, unusual non-tidal water levels during topsides / GBS mating, and historically extreme sea ice conditions that delayed tow-to-field operations. Topsides marine operations required data collection and forecasting system enhancements more than 2 years in advance due to the sensitivity of the operations, and the complex topography and climate of the site. Installation offshore was limited by winds, seas and long period swells that could reach the site from remote areas of the Atlantic. A summary of metocean support for the Hebron Platform is presented with lessons learned and comparisons made with the Hibernia Construction Project executed 20 years earlier in the same location.\u0000 Several technologies were applied to the Hebron Project that were not available during the Hibernia Project. Emerging technologies combined with in-situ measurements of atmospheric and oceanic conditions were used to provide operational metocean support for the Hebron Project. Examples of effective processes are described that could apply to similar harsh environments, complex terrains or northern coastal construction projects. There were also technologies attempted which were deemed unfeasible. Complex metocean decision making for an environmentally sensitive oil and gas construction project is described within a quantitative risk assessment framework.\u0000 Embedded experienced metocean personnel used advanced information behind the scenes to improve forecast accuracy and to provide guidance on the timing and likelihood of threshold-exceedance events. It was demonstrated that an effective metocean decision making process was highly dependent on forecast magnitude and timing accuracy at various forecast horizons. It was found that specific operational parameters and governing, operational weather windows for the Hebron Project were achieved with minimal waiting on weather due to a ‘go/no-go’ decision making process which was based on confidence in the forecast accuracy, and a risk assessment system that embedded metocean specialists with the relevant event-likelihood information. Operational delays due to unreliable forecasting would have led to significant delays, personnel and equipment downtime, and cost over-runs for the Hebron Project.\u0000 Weather forecasting in support of the Hebron Project demonstrated that metocean analytic and predictive science has improved sufficiently over the past 20 years to effectively support oil and gas exploration and development operations that have moved into harsher environments.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130889817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Impact of Real-Time Data in Improving the Efficiency, Safety and Productivity of Wells During the Installation of Lower Completion Assemblies in the Complex Deepwater Environment","authors":"A. Hawthorn, Lei Fang, E. O'Malley","doi":"10.4043/29584-MS","DOIUrl":"https://doi.org/10.4043/29584-MS","url":null,"abstract":"\u0000 As wells have become deeper with more highly complex well trajectories and tighter mud weight windows, there has been an increase in the amount of Non Productive Time associated with installing lower completion assemblies. One of the key issues in safely and efficiently installing these complex assemblies is that, as these wells have become more complex, the traditional methods of utilizing surface measurements and extrapolating or modeling what is actually happening downhole has started to run into problems. Models for torque and drag and hydraulics that worked in shallower and less complex wells with large pressure windows often fail to actually predict what is happening downhole, leading to extreme inefficiencies and sub-optimal or in extreme cases complete failure of the installation. In certain circumstances surface data and models may indicate almost the exact opposite of what is actually occurring downhole.\u0000 This paper will demonstrate through case histories in the complex deepwater environment the use of an easy to deploy acoustic telemetry and measurement network that can be run in conjunction with any lower completion assembly to minimize these risks and to optimize the workflows. Data will be shown from the full range of lower completion operations including TCP gun runs, displacement operations and throughout the actual fracing operation itself. This system is completely wireless and can send data through the wall of regular drillpipe without requiring any modification of surface or downhole equipment. Data can be provided back to surface irrespective of fluid, flow or formation type and also during tripping in and out of the hole. Downhole and along string measurement of weight, torque, internal and external pressures and temperatures provide the key data allowing real-time decision to be made on what is actually happening downhole.\u0000 The case histories will show how material gains were made by using and acting on this real-time data leading to safer, more efficient and in some case enhanced productivity from these wells.\u0000 This paper will show how this real-time downhole data is now readily available and how it has been used to solve problems and optimize the efficiency of operations throughout lower completion installation. Real-time downhole data, which has revolutionized the drilling of wells in the last couple of decades, is now for the first time available to solve the complex issues associated with lower completion operations. If this access to real-time downhole data provides even half of the gains in efficiency and safety seen in the drilling environment, moving forward huge gains may be realized throughout completion operations.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123820048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining Integrity in 5,000 Feet of Water Following a Major Incident","authors":"D. Wisch","doi":"10.4043/29228-MS","DOIUrl":"https://doi.org/10.4043/29228-MS","url":null,"abstract":"\u0000 Prior to the completion of installation of the Big Foot TLP, 9 of 16 pre-installed tendons fell to the seafloor. Seven of the tendon assemblies were reverse installed. Nine of the tendons lay on the seafloor with the lower connector assemblies remaining within the piles and receptacle device. A critical go forward decision was determination of reusability of the pile/receiver assemblies. The pile/receiver assemblies were located in over 5,000 feet of water. Novel technology application and deployment was needed to clear the site, inspect remaining components, determine integrity and adequacy. The decision was time bound as go-forward decisions relied on the outcome of the study.\u0000 This paper outlines the fallen condition, development of criteria to assure adequacy, identification of technologies sufficient to determine adequacy, interpretation of the data, engineering assessment and final decisions. Initial clearing of site included removal of lower tendon sections and connectors without incurring damage to the pile assembly was required. Marinizing inspection tools, templates, etc. for both accuracy and repeatability was required. The novel and successful execution starting with \"as is\" condition through design, deployment and results will be highlighted. One key element was mapping the after-incident conditions to the design tolerances.\u0000 Developing tools and operating procedures to assure measuring tolerances and repeatability required new methods and procedures that proved successful. For a first of kind and unique challenge, the importance of starting with first principles and initial acceptance criteria, identifying technologies and tools available to match, followed by selection of most likely to succeed in extending existing tools for success is illustrated.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122043754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Critical Role of International Standards and Certification for the Marine Energy Industry","authors":"Jonathan Colby, P. Staby, W. Musial","doi":"10.4043/29341-MS","DOIUrl":"https://doi.org/10.4043/29341-MS","url":null,"abstract":"\u0000 In 2007 the International Electrotechnical Commission (IEC) initiated Technical Committee (TC) IEC/TC 114 to develop standards for marine energy converters including wave, tidal and other water current converters. Following the inaugural plenary meeting in 2008, the first IEC/TC 114 Technical Specification (TS), Terminology, was published in 2011 and significant work on the development of other TSs is ongoing. Initial conformity assessment activities began in 2011 and the Marine Energy Operational Management Committee (ME-OMC) of the IEC Renewable Energy (IECRE) System was established in 2014. An update on the status of international, consensus-based, marine energy standards and certification deliverables will be provided, including the development of Renewable Energy Test Reports (RETRs) under the IECRE.\u0000 Currently, IEC/TC 114 has fourteen participating member (P-Member) countries and thirteen observer member (O-Member) countries. Nine Project Teams (PTs), two Ad-hoc Groups (AHGs), and seven Maintenance Teams (MTs) are engaged in writing new TSs, assessing information on TS applications and preparing the published TSs for release of 2nd Editions. To date, IEC/TC 114 has published ten TSs covering subjects including wave and tidal energy converter performance assessment and wave and tidal resource assessment. Additional TSs are expected to be published in 2019 covering river and ocean thermal energy converters and resources, among others.\u0000 TSs developed by IEC/TC 114 and applied by the industry are essential to reduce risk and increase confidence in marine energy systems. These TSs serve as the fundamental underpinnings of international, 3rd party conformity assessment systems, such as the IECRE. The IECRE is currently comprised of fifteen Member Bodies and operates three Sectors: Marine Energy (ME), Solar Photovoltaic (PV) and Wind Energy (WE). The IECRE ME sector has reached a critical milestone in the development of 3rd party conformity assessment deliverables for the marine energy industry. With the approval of IECRE 03 Ed. 2 and OD 300-200 Ed. 1, the ME Sector established a mechanism for the acceptance of Renewable Energy Test Laboratories (RETLs) with a scope in the IEC TS 62600-200 (Power Performance Assessment of Electricity Producing Tidal Energy Converters). A three-year transition period for test laboratory self- assessment based on ISO/IEC 17025 accreditation has been implemented to encourage RETL participation in the ME Sector.\u0000 A detailed review of IEC/TC 114 and ME-OMC activities is provided and the critical connection between the development and implementation of international standards, and the associated conformity assessment rules and procedures, and the continued growth and commercial success of the marine energy industry is highlighted and examined. Emphasis is given to the role standards and certification play in risk reduction, improved quality and reliability, and increased confidence for the entire range of industry sta","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"345 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115970075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ocean Current Statistics in the Gulf of Mexico Derived from an Ensemble Approach","authors":"A. Srinivasan, N. Sharma, Drew Gustafson, M. Iskandarani, O. Knio, C. Thacker","doi":"10.4043/29435-MS","DOIUrl":"https://doi.org/10.4043/29435-MS","url":null,"abstract":"\u0000 Ocean currents are an important consideration throughout the life cycle of the many offshore projects. These currents are complex, three dimensional, dynamic and as yet poorly characterized in a statistical sense. Numerical ocean circulation models are increasingly sophisticated and are beginning to capture the structure and variability of complex ocean current systems. The starting point for model-based characterization of currents is a long time series of model outputs obtained at high spatial and temporal resolution. There are an ever-increasing number of model products, but it is not clear how to identify suitable products for a given application. Frequently, a familiar product is chosen that may not be the best choice. Here, we present an alternative approach wherein a collection of model runs, referred to as an ensemble, is used to estimate ocean current statistics at points of interest. Unlike other ensemble methods where the ensemble is used to estimate the statistics directly, we use the ensemble to construct a surrogate ocean model or an emulator using polynomial expansions. This emulator is computationally inexpensive to run and is used to sample the model outputs for large numbers of model inputs to generate full probability distributions of the model state, which can then be used to derive statistics required for design criteria. We have used the above technique to build an emulator for a numerical circulation model of the Gulf of Mexico. We present statistics of the Loop Current derived from this approach and briefly compare it with statistics obtained from measurements and other available long time-series of model outputs. Probability distributions for a sample point in the vicinity of the Loop Current are presented. It is shown that the technique can provide robust statistics and complements existing techniques.","PeriodicalId":214691,"journal":{"name":"Day 4 Thu, May 09, 2019","volume":"48 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130005457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}