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The Arabian Sea, influenced by the Indian monsoon, has many unique features, including its basin-scale seasonally reversing surface circulation and the Great Whirl, a seasonal anticyclonic system appearing during the southwest monsoon close to the western boundary. To establish a comprehensive dynamical picture of the Arabian Sea, we utilize numerical model output and design a full vorticity budget that includes a fully decomposed nonlinear term. The ocean general circulation model has 0.1° resolution and is mesoscale eddy-resolving in the region. In the western boundary current system, we highlight the role of nonlinear eddies in the life cycle of the Great Whirl. The nonlinear eddy term is of leading-order importance in this feature’s vorticity balance. Specifically, it contributes to the Great Whirl’s persistence in boreal fall after the weakening of the southwesterly winds. In the open ocean, Sverdrup dynamics and annual Rossby waves are found to dominate the vorticity balance; the latter is considered as a key factor in the formation of the Great Whirl and the seasonal reversal of the western boundary current. In addition, we discuss different forms of vertically integrated vorticity equations in the model and argue that the bottom pressure torque term can be interpreted analogously as friction in the western boundary and vortex stretching in the open ocean.

Herein, seasonal velocity variations from the sea surface to a depth of 1000 m over the entire Kuroshio path are investigated using satellite altimetry and reanalysis datasets. The data analysis results show that velocities in the upper layer (from 0 to approximately 500 m) reach a maximum in July and a minimum in autumn (October to November) or winter (December to February) with different tendencies in each region. However, those in the lower layer (> 500 m depth) show a reversed seasonal variation—reaching a maximum in winter—especially in the continental slope area from the east of Luzon Island to the east of the Ryukyu Islands chain, which is regarded as a route of the deeper Kuroshio flow. Using a realistic general circulation model, we performed numerical experiments to clarify the role of the local wind stress as the driving force in seasonal Kuroshio velocity variations in the upper layer. These experiments revealed that seasonal Kuroshio velocity variations in the upper layer are mainly caused by the local response to wind stress upon the current itself. These numerical results cannot be explained by conventional mechanisms, such as flow–topography interactions or coastal upwelling/downwelling. On the other hand, seasonal Kuroshio velocity variations in the lower layer can be explained by the Sverdrup theory, in which barotropic responses to the wind stress curl over the area west of the Izu–Ogasawara Ridge are responsible.

The upper Paleozoic succession along the northwest margin of the Canadian Arctic Sverdrup Basin is little studied and poorly understood yet has the potential to yield insights into the paleogeographic and tectonic evolution of the Arctic regions including Crockerland. Carboniferous and Permian drill cuttings were collected from five exploration wells on Brock, Mackenzie King, and Ellef Ringnes islands. Seven unconformity-bounded sequences were identified and correlated. Reflection seismic interpreted on Ellef Ringnes Island indicates that a major syn-sedimentary fault offsets the Mississippian succession bounding a down-to-the-north half-graben. Late Pennsylvanian (Gzhelian) fault reactivation, associated with the Melvillian Disturbance, created a depression that extended northward and was bordered to the south by a structural high. Episodic minor fault reactivation occurred until the Early–Middle Permian boundary. During the latest Early Permian (Kungurian), sand derived from Crockerland prograded southward onto the Sverdrup Basin’s northwest margin and continued into the Roadian. After a lull during the Wordian, clastic progradation resumed in the Capitanian. Detrital zircon U–Pb ages recovered from Kungurian and Roadian samples on Brock and Ellef Ringnes islands display Devonian Clastic Wedge (DCW) signatures. A Moscovian–Artinskian carbonate blanket likely covered Crockerland and sheltered DCW material from erosion, implying it was a subsiding, carbonate bank throughout most of the Pennsylvanian – Early Permian. Base level fall in the Kungurian, associated with a transition to a more humid climate, breached these carbonate rocks to allow erosion and transportation of DCW material. Recycling of the DCW started earlier (Artinskian) and peaked later (Wordian) along the southern margin of the basin.

Eleven climate system models that participate in the Coupled Model Intercomparison Project phase 5 (CMIP5) were evaluated based on an assessment of their simulated meridional transports in comparison with the Sverdrup transports. The analyses show that the simulated North Pacific Ocean circulation is essentially in Sverdrup balance in most of the 11 models while the Argo geostrophic meridional transports indicate significant non-Sverdrup gyre circulation in the tropical North Pacific Ocean. The climate models overestimated the observed tropical and subtropical volume transports significantly. The non-Sverdrup gyre circulation leads to non-Sverdrup heat and salt transports, the absence of which in the CMIP5 simulations suggests deficiencies of the CMIP5 model dynamics in simulating the realistic meridional volume, heat, and salt transports of the ocean.

Indonesia is a country that has an area of sea three times larger than the land area. In line with the rapid development, the need for electricity is also increasing. So that Indonesia has great potential to produce alternative and environmentally friendly energy, namely Sea Wave Energy. Its continuous nature is available all the time. Many potential coastal areas in Indonesia, however, have not been utilized optimally. The purpose of this study is to see the potential of Wave Energy for electricity. For this reason, research was carried out at a location in the Central Sulawesi area, precisely in Salubomba, Central Banawa District, Donggala Regency. In this study a potential study was conducted on 3 types of PLTGL, namely Buoy, OWC, and Pasut Dam, where one will be chosen that meets the wave criteria requirements on the Beach. From the results of research, PLTGL that fulfills the requirements is the type of buoy. Data collection begins with secondary data, namely wind data from Mutiara Station. Then proceed with calculating wave forecasting using the SMB (Sverdrup Munk-Bretschneider) method. The results of this study, Salubomba beach has the potential to be built by the Buoy Type Wave Power Plant, a significant wave height of 0.52 - 3.37 meters with a ruptured depth of 3.95 meters.

This paper considers the general ocean circulation (GOC) within the thermodynamical closure of our climate theory, which aims to deduce the generic climate state from first principles. The preceding papers of this theory have reduced planetary fluids to warm/cold masses and determined their bulk properties, which provide prior constraints for the derivation of the upper-bound circulation when the potential vorticity (PV) is homogenized in moving masses. In a companion paper on the general atmosphere circulation (GAC), this upper bound is seen to reproduce the observed prevailing wind, therefore forsaking discordant explanations of the easterly trade winds and the polar jet stream. In this paper on the ocean, we again show that this upper bound may replicate broad features of the observed circulation, including a western-intensified subtropical gyre and a counter-rotating tropical gyre feeding the equatorial undercurrent. Since PV homogenization has short-circuited the wind curl, the Sverdrup dynamics does not need to be the sole progenitor of the western intensification, as commonly perceived. Together with GAC, we posit that PV homogenization provides a unifying dynamical principle of the large-scale planetary circulation, which may be interpreted as the maximum macroscopic motion extractable by microscopic stirring, within the confines of thermal differentiation.

Fiber Optic (FO) sensing capabilities for downhole monitoring include, among other techniques, Distributed Temperature Sensing (DTS) and Distributed Acoustic Sensing (DAS). The appeal of DTS and DAS data is based on its high temporal and spatial sampling, allowing for very fine localization of processes in a wellbore. Furthermore, the broad frequency spectrum that especially DAS data is acquired with, enables observations, ranging from more continuous effects like oil flow, to more distinct effects like opening and closing of valves. Due to the high data volume of hundreds of Gb per well per hour, DAS data has traditionally been acquired acquisition-based, where data is recorded for a limited amount of time and processed at a later point in time. This limits the decision-making capability based on this data as reacting to events is only possible long after the event occurred. Equinor has addressed these decision-making shortcomings by building a real-time streaming solution for transferring, processing, and interpretation of its FO data at the Johan Sverdrup field in the North Sea. The streaming solution for FO data consists of offshore interrogators streaming raw DAS and DTS data via a dedicated bandwidth to an onshore processing cluster. There, DAS data is transformed into FO feature data, e.g., Frequency Band Energies, which are heavily decimated versions of the raw data; allowing insight extraction, while significantly reducing data volumes. DTS and DAS FO feature data are then streamed to a custom-made, cloud-based visualization and integration platform. This cloud-based platform allows efficient inspection of large data sets, control and evaluation of applications based on these data, and sharing of FO data within the Johan Sverdrup asset. During the last year, this FO data streaming pipeline has processed several tens of PB of FO data, monitoring a range of well operations and processes. Qualitatively, the benefits and potential of the real-time data acquisitions have been illustrated by providing a greater understanding of current well conditions and processes. Alongside the FO data pipeline, multiple prototype applications have been developed for automated monitoring of Gas Lift Valves, Safety Valve operations, Gas Lift rate estimation, and monitoring production start-up, all providing insights in real-time. For certain use cases, such as monitoring production start-up, the FO data provides a previously non-existent monitoring solution. In this paper, we will discuss in detail the FO data pipeline architecture from-platform-to-cloud, illustrate several data examples, and discuss the way-forward for "real-time" FO data analytics.

Cyclonic and anticyclonic eddies are usually characterized by upwelling and downwelling, respectively, which are induced by eddy pumping near their core. Using a repeated expendable bathythermograph transect (XBT) and Argo floats, and by cruise experiments, we determined that not all eddies in the northern South China Sea (NSCS) were accompanied by eddy pumping. The weakening of background thermocline was attributed to the strengthening of eddy pumping, affected by (1) wind-induced meridional Sverdrup transports and (2) Kuroshio intrusion into the NSCS. Higher particulate organic carbon (POC) fluxes (> 100 mg-C m−2 day−1) were found near the eddy cores with significant eddy pumping (defined by a depth change of 22°C isotherm near the thermocline for over 10 m), although the satellite-estimated POC fluxes were inconsistent with the in-situ POC fluxes. nitrogen limitation transition and high POC flux were even found near the core of a smaller mesoscale (diameter < 100 km) cyclonic eddy in May 2014, during the weakening of the background thermocline in the NSCS. This finding provides evidence that small mesoscale eddies can efficiently provide nutrients to the subsurface, and that they can remove carbon from the euphotic zone. This is important for global warming, which generally strengthens upper ocean stratification.

Occurrence of phytoplankton bloom in the northern Arabian Sea (NAS) during the winter monsoon is perplexing. The convective mixing leads to a deeper and well-oxygenated (> 95% saturation) mixed layer. We encountered low chlorophyll conditions though the nutrient conditions were favorable for a bloom. The mean ratio of silicate (Si) to DIN (Dissolved Inorganic Nitrogen: nitrate + nitrite + ammonium) in the euphotic zone was 0.52 indicating a “silicate-stressed” condition for the proliferation of diatoms. Also, the euphotic depth was much shallower (~ 49 m) than the mixed layer (~ 110 m) suggesting the Sverdrup critical depth limitation in the NAS. We show that the bloom in this region initiates only when the mixed layer shoals towards the euphotic zone. Our observations further suggest that two primary factors, the stoichiometric ratio of nutrients, especially the Si/DIN ratio, in the mixed layer and re-stratification of the upper water column, govern the phytoplankton blooming in NAS during the later winter monsoon. The important finding of the present study is that the Sverdrup’s critical depth limitation gives rise to the observed low chl-a concentration in the NAS, despite having enough nutrients.

High concentrations of mercury, possibly connected with widespread volcanism of the Siberian Traps, have previously been associated with the Smithian/Spathian (Early Triassic) boundary (SSB) in the Sverdrup Basin, Tethyan sections in India and China, as well as with a shallow-water record in western Spitsbergen. We confirm this Hg/TOC anomaly in the deeper water record at Wallenbergfjellet, central Spitsbergen. However, both paleontological age control and carbon isotopes indicate that the Hg anomaly occurred mainly within strata of middle Smithian age. Therefore, this Hg anomaly is unlikely to be directly and causally related to mechanisms contributing to the late Smithian global extinction of nektonic faunas. The TOC and trace element data suggest generally more oxygenated conditions during the Smithian compared to the Spathian, which is at odds with the hypothesis that oxygen depletion may have been a global kill mechanism for the SSB extinction. Further work is needed to assess if precise timing and paleogeographic distribution of anoxia shows any consistent pattern or not during the Smithian and Spathian. The very abrupt lower limb of the positive carbon isotope excursion (CIE) and the coarser grain size immediately below the boundary between the Lusitaniadalen Member and the Vendomdalen Member indicate a substantial stratigraphic gap of latest Smithian age, a previously neglected signal shared with many other boreal SSB sections. Ammonoid age control also indicates that the onset of the late Smithian gap in the high latitudes was earlier than in the Tropics. The gradual end of the positive CIE contrasts with the frequent spike shape observed in tropical shelf records and is definitively earliest Spathian in age. The middle Smithian Hg anomaly in the Boreal record is only visible in the Hg/TOC values, and is associated with a possible shift in organic matter type from terrestrial to marine in the case of Spitsbergen. This suggests that the middle Smithian Hg/TOC anomaly in Spitsbergen may not unequivocally originate from volcanism, and calls for additional caution before interpreting Hg spikes as a volcanic proxy.

A model of an advective thermocline is proposed for the case of continuously stratified Sverdrup circulation with a ventilated layer caused by the divergence of flows in the Ekman layer: an immiscible layer with homogenized vorticity and a layer of abyssal liquid, which applies to anticyclonic gyre waters. The results of calculations for the Atlantic Ocean (region 15-52°N, 00-63°E) made with this model are presented. With an abyssal density of 28.0, the values of the surface density and density of the unventilated layer grow to the north from 24.2 to 27.0 and from 27.8 to 27.9, respectively, with an almost zonal distribution, i.e. ventilation zones have latitudinal circles. From calculations of the depths of wind circulation, it follows that the ventilating layer is as deep as 900 m in the north-western region and raises to 250 m in the southern and eastern parts of the basin. The same tendency is traced for the depth of the gyre, but here there is an increase in depth from 500 to 1500 m. The active dynamics in the ventilating layer and the shadow area on the eastern border are noted. The structure of the thermocline is demonstrated with a typical zonal section, characterizing a much larger isopycnic increment for ventilated layers than in non-ventilated layers.

We have revealed the features of similarity and difference in Mesozoic sedimentation history of the East Barents and Sverdrup sedimentary basins based on sea areas, sedimentary masses per time unit and coefficient of the sand content. During the end of Paleozoic and in Mesozoic times both basins have been located near each other but didn’t merged into the one great basin.

In this interview, Carl Wunsch talks with Walter Munk about his career in oceanography; his relationships with scientists such as Harald Sverdrup, Roger Revelle, Walfrid Ekman, Carl Rossby, Carl Eckart, Henry Stommel, and G.I. Taylor; technological advances over the decades; and his thoughts on the future of the field.

A model of an advective thermocline is proposed for the case of continuously stratified Sverdrup circulation with a ventilated layer caused by the divergence of flows in the Ekman layer: an immiscible layer with homogenized vorticity and a layer of abyssal liquid, which applies to anticyclonic gyre waters. The results of calculations for the Atlantic Ocean (region 15–52° N, 0–63° E) carried out with this model are presented. With an abyssal density of 28.0, the values of the surface density and density of the unventilated layer increase to the north from 24.2 to 27.0 and from 27.8 to 27.9, respectively, with an almost zonal distribution; i.e., ventilation zones have latitudinal circles. From calculations of the depths of wind circulation, it follows that the ventilated layer is as deep as 900 m in the northwestern region and rises to 250 m in the southern and eastern parts of the basin. The same tendency is traced for the depth of the gyre, but here there is an increase in depth from 500 to 1500 m. The active dynamics in the ventilating layer and the shadow area on the eastern border are noted. The structure of the thermocline is demonstrated with a typical zonal section, characterizing a much larger isopycnic increment for ventilated layers than in nonventilated layers.

The upper-layer circulation in the Tropical Northwest Pacific Ocean (TNWP) is characterized by the alternating zonal currents, such as North Equatorial Current (NEC) and Subtropical Countercurrent (STCC). The variabilities of the upper-layer zonal currents in the TNWP, which were obtained directly from 75 kHz acoustic Doppler current profiler (ADCP) measurements and indirectly from geostrophic calculations, were investigated on intraseasonal to interannual timescales from 2006 to 2014. Surface geostrophic current derived from sea surface height anomaly (SSHA) approximated well to the in-situ measurements with ADCP that was slightly better than the absolute geostrophic current obtained from AVISO. The interannual signals related to the El Nino-Southern Oscillation (ENSO) were quite apparent, especially near the boundary (about 17.5°N–19°N) between NEC and STCC. We found that the eastward-flowing southern STCC develops during the decaying phase of ENSO and weakens during La Nina. Strong easterlies during strong La Nina (e.g., 2010 La Nina event) seem to influence NEC to expand further north to the southern STCC region and this coincides with the meridional migration of the Sverdrup streamfunction. The southern STCC region is profoundly influenced by the mesoscale/sub-mesoscale eddy activities, which can intensify the eastward flow of STCC and ultimately contribute to the intraseasonal signal. We found that this intraseasonal signal weakened when La Nina happened in 2010, which is presumably associated with the northward expansion of NEC. Possible factors related to the discrepancies between surface geostrophic current and sub-surface ADCP data are discussed.

A comparative analysis of two large Arctic sedimentary basins was performed: the Sverdrup and East Barents, with emphasis on the quantitative parameters of sedimentation in the Mesozoic, determined by A.B. Ronov’s volumetric method. The similarities and differences of both basins are revealed, in particular, in sediment accumulation areas, in masses of sedimentary material per time unit, and in gross sand ratio. It was concluded that at the end of the Paleozoic and in the Mesozoic, both basins were close to each other but did not merge into one structure. In the Cenozoic, the distance between the basins increased due to spreading of the Eurasian Basin.

Using 3D broadband seismic data, we have investigated low-frequency seismic amplitude anomalies associated with and below various geologic formations in the Johan Sverdrup oil field situated in the central North Sea. Low-frequency anomalies are observed below the Intra-Draupne and the Heather and Hugin reservoirs, at the Svarte and Tor Fms, and below shallow channels. The Intra-Draupne Fm is the main oil reservoir of interest in the field, and it is relatively homogeneous, with observed low [Formula: see text] values of approximately 25–30. The Heather and Hugin reservoirs, which underlie the Intra-Draupne, are heterogeneous and oil bearing. We performed three-layer elastic modeling on a simple reservoir model based on the properties of the Intra-Draupne Fm, and the results suggest that as the thickness of the middle oil-bearing layer increases the dominant frequency decreases due to the tuning effect. The Svarte and Tor Formations are shallower in the section and are fractured. Low-frequency anomalies associated with these formations seem to indicate a clear correlation with zones of increased fracture density interpreted from high-resolution most-negative-curvature attribute maps. Low-frequency anomalies are also observed below shallow gas channels consisting of stratified sandy and shaly intervals with vertical variations in porosity and permeability. In addition, stacking tests using coarse and fine velocity analysis indicate no noticeable difference in the characteristics of the low-frequency anomalies, in general, at all levels. We conclude, therefore, that the observed low-frequency anomalies are unrelated to stacking issues.

During Late Cretaceous times the Sverdrup Basin, Arctic Canada, received considerable air-fall volcanic material. This is manifested as numerous centimetre- to decimetre-thick diagenetically altered volcanic ash layers (bentonites) that occur interbedded with mudstones of the Kanguk Formation. Previous research on bentonite samples from an outcrop section in the east of the basin (Sawtooth Range, Ellesmere Island) revealed two distinct volcanic sources for the bentonites: most of the bentonites analysed (n=9) are relatively thick (0.1 to 5 m), were originally alkaline felsic ashes, and were likely sourced from local volcanic centres on northern Ellesmere Island or the Alpha Ridge that were associated with the High Arctic Large Igneous Province (HALIP). Two thinner (To better understand volcanism within the vicinity of the Sverdrup Basin during Late Cretaceous times, and further test the above interpretations, a larger suite of bentonite samples was investigated, drawing on samples from outcrop sections in the central and eastern Sverdrup Basin. Whole-rock geochemical analyses and combined zircon U-Pb age and Hf isotope analyses were undertaken. The vast majority of bentonites analysed to date have alkaline geochemistry and were likely sourced from proximal volcanic centres related to the HALIP. The combined U-Pb and Hf isotope data from these bentonites show a progression from evolved (-2 to 0) to moderately juvenile (+9 to +10) εHf(t) values between late Cenomanian and early Campanian times (c. 97–81 Ma). This is interpreted to record compositional change through time within the local HALIP magmatic system.

Located along the Canadian polar continental margin, the Sverdrup Basin is an elongated, intracontinental sedimentary basin that originated during Carboniferous-Early Permian rifting. Starting in the Early Cretaceous, volcanic complexes (VC) were emplaced throughout the basin, which are associated with the High Arctic Large Igneous Province (HALIP). Geochronological and geochemical data on HALIP rocks exposed on Axel Heiberg Island and northern Ellesmere Island suggest several discrete stages of emplacement; (1) voluminous mafic intrusive activity of tholeiitic character accompanied by minor extrusive volcanism at ca. 125-110 Ma (VC1a); the eruption of tholeiitic flood basalts on Axel Heiberg Island at ca. 100-90 Ma (VC1b); the emplacement of mildly alkaline lava flows, sills and dykes on Ellesmere Island at ca. 100-90 Ma (VC2); and the eruption of a suite of alkaline lava flows from central volcanoes at ca. 85-75 Ma (VC3). Each magmatic episode is characterized by a distinctive eruptive style and coherent geochemical signature regardless of the mode of emplacement. In this context, onshore manifestations of the HALIP can be viewed as time-markers in the evolution of the adjacent polar continental margin.We use digital plate tectonic models, constructed via the GPlates software, to explore the parallel development of the Sverdrup Basin and proto-Arctic Ocean (Amerasia Basin) during the Early Cretaceous, and the transition from a sedimentary to volcanic Sverdrup Basin. Plate reconstructions of the Amerasia Basin at ca. 125 Ma suggest two zones of extension; one within the Canada Basin, which may include seafloor spreading, (Zone 1, more distal to the Sverdrup Basin) and the second further northwards in the Alpha-Mendeleev Ridge and Makarov Basin domains offshore northern Ellesmere Island (Zone 2, proximal to the northeastern portion of the Sverdrup Basin). The potential for enhanced melting caused by mantle flow (possibly related to the arrival of a mantle plume) towards the Sverdrup Basin depocentre could explain widespread magmatism of tholeiitic character from ca. 125-90 Ma (VC1). The transition to mildly alkaline (VC2) and alkaline magmatism (VC3) at ca. 100 Ma may have signaled the end of extension in Zone 1. The persistence of localized extension in Zone 2 could explain the shift in magmatic style and compositional diversity of igneous rocks emplaced at intrusive complexes (VC2) vs constructional volcanic edifices (VC3). In addition, greater depth to Moho along the northeastern Sverdrup Basin may have contributed to restricted mantle flow in Zone 2. We propose that the spatio-temporal evolution of HALIP magmatism in the Sverdrup Basin during the Cretaceous relates to (1) different styles of tectonic extension (distal vs proximal, protracted vs discrete, widespread vs narrow, seafloor spreading vs hyper-extensional rifting), and (2) the presence of hot, thin lithosphere close to the basin depocentre vs cold and thick lithosphere in the northeastern part of the basin.

In his 1953 paper, Harald Sverdrup argued that the development of a spring bloom in the ocean depends on the juxtaposition of two depth horizons: the mixed-layer depth and the critical depth. Mixed-layer depth shallower than the critical depth favours phytoplankton growth in the layer and vice versa. However, mathematically, Sverdrup left the problem unsolved in the form of a transcendental equation. In spite of the high number of citations that this paper has garnered, the solution to this equation has not been found, until now. In this work, we present an analytical solution for the critical depth, as originally defined by Sverdrup. The paper opens with the definition of the critical depth and the description of the Lambert W function. The analytical solution for critical depth follows. Sverdrup’s original model is extended to include the effect of light attenuation by phytoplankton and the analytical solution for steady-state biomass in the mixed layer is derived. The expression for mixed-layer production at steady state is also presented. Two novel variants of the critical depth are defined: the optically uncoupled critical depth and the optically coupled critical depth. It is demonstrated that at steady state the optically coupled critical depth equals the mixed-layer depth and that the irradiance at the base of the mixed layer equals the irradiance at the optically uncoupled critical depth. Competitive exclusion is demonstrated to hold and the optically uncoupled critical depth is linked to the critical light intensity in multi-species competition. Finally, a conservation principle for the critical depth is found.

Wave information is crucial for maritime activities such as marine transportation, offshore exploration, fisheries, safety management system on ships, coastal development, and coastal disaster mitigation. The Sverdrup, Munk, Bretschneider. SMB is one of the most common methods used for wave forecasting. In the present study, we examine the validation of Easywave, an algorithm that automates wave forecasting with the SMB method. The results are validated using observational data and analyzed using Mean Relative Error (MRE), Root Mean Square Error (RMSE), and a bias value. The level of accuracy of forecasting using the Easywave algorithm is 89.87% for Hs and 78.43% for Ts. The level of precision obtained by on-field observation data is $\pm \mathbf{0.14\ m}$ for Hs and $\pm\mathbf{0.26\ s}$ for Ts.

A new carbon isotope record for two high-latitude sedimentary successions that span the Jurassic–Cretaceous boundary interval in the Sverdrup Basin of Arctic Canada is presented. This study, combined with other published Arctic data, shows a large negative isotopic excursion of organic carbon (δ13Corg) of 4‰ (V-PDB) and to a minimum of −30.7‰ in the probable middle Volgian Stage. This is followed by a return to less negative values ofc. −27‰. A smaller positive excursion in the Valanginian Stage ofc. 2‰, reaching maximum values of −24.6‰, is related to the Weissert Event. The Volgian isotopic trends are consistent with other high-latitude records but do not appear in δ13Ccarbrecords of Tethyan Tithonian strata. In the absence of any obvious definitive cause for the depleted δ13Corganomaly, we suggest several possible contributing factors. The Sverdrup Basin and other Arctic areas may have experienced compositional evolution away from open-marine δ13C values during the Volgian Age due to low global or large-scale regional sea levels, and later become effectively coupled to global oceans by Valanginian time when sea level rose. A geologically sudden increase in volcanism may have caused the large negative δ13Corgvalues seen in the Arctic Volgian records but the lack of precise geochronological age control for the Jurassic–Cretaceous boundary precludes direct comparison with potentially coincident events, such as the Shatsky Rise. This study offers improved correlation constraints and a refined C-isotope curve for the Boreal region throughout latest Jurassic and earliest Cretaceous time.

The Operator and the license partnership have set an extremely high ambition for recovery from the Johan Sverdrup field, even before a barrel of oil has been produced. How is this possible? This paper describes the characteristics of the reservoir, as well as early assessments and investments for improved oil recovery (IOR) to ensure flexibility. In addition, data acquisition, reservoir monitoring, new technologies and digitalisation, as well as new ways of working are addressed. This will be the key enablers for a recovery of more than 70% of the field’s oil resources. Johan Sverdrup is the third largest oil field on the Norwegian Continental Shelf (NCS) with a recoverable volume range of 2,2 to 3,2 billion b.o.e. The reservoir is characterized by excellent reservoir properties with a strongly undersaturated oil. The primary drainage strategy is water flooding, including re-injection of all produced water, supplemented by water-alternating-gas (WAG) injection at the end of the oil production plateau. The field came on stream in October 2019. Going back to the early stages of the Johan Sverdrup field development, it was obvious from the start that this would be an independent development solution with a long lifetime. Given the excellent reservoir, this was considered as a unique opportunity to plan for a high resource exploitation, and make sure that future business opportunities in this context could be utilized in a technical and economically attractive way. A very early screening was conducted to investigate which IOR measures should be further matured. With subsurface evaluations as the base, this maturation also included assessments on technical feasibility and potential implications for development solutions. The objective was to ensure sufficient flexibility in early field design. It also implied that the Johan Sverdrup license had to consider pre-investments prior to any implementation decision. Data acquisition and reservoir monitoring strategies were also started early on, which e.g. led to a full field Permanent Reservoir Monitoring (PRM) decision, with installation starting summer 2019. This gives a baseline for parts of the field before production start, and when completed in 2020 it will be the world’s largest fiber based PRM system. Fiber optics are also installed in the wells. In addition, a dedicated observation well is part of the development plan. The idea is that PRM and fiber data results, in addition to repeated logging in the observation well, will be key information to evaluate business cases for future IOR or new technology measures. Digitalisation has also been a key aspect of this, and several subsurface-focused digitalisation initiatives have been implemented during the field development, giving the operator the opportunity to implement new ways of working and enabling new ways of cooperation in the partnership as data and applications are shared within the owner group in a digital setting. The overall objective of digitalisation in this context is to further optimize the analysis and management of the Johan Sverdrup reservoir – and hence value of the Johan Sverdrup field – for the license owners.

The pre-drilling campaign for the Johan Sverdrup development was a key contributor to the successful execution of the first phase of the mega-project. The initial pre-drilling plan consisted of drilling six (6) oil producers, seven (7) subsea injectors and one (1) pilot target. At the end of the campaign, however, as many as eight (8) oil producers, twelve (12) subsea injectors and six (6) pilot targets had been drilled, more than one year ahead of the original schedule and NOK 7 billion (nearly 800 million USD) below budget. All the wells in the pre-drilling campaign were drilled by the semi-submersible drilling unit Deepsea Atlantic (Odfjell Drilling) and the objectives were met on all wells. After a summary of the results of the campaign, the focus of this paper is to identify some of the key success factors behind the campaign and attempts to draw lessons-learned of relevance to future drilling campaigns. Key areas to be assessed in the paper include: contract strategies including the use of integrated service and rig contracts with common incentives to develop and maintain a "One-Team" mentality; the further development of the ‘perfect well’ approach and Lean methodology to minimize waste and maximize efficiency of the campaign; as well as efforts and arenas to systematically promote collaboration, openness and regular experience transfer among the different parties involved (operator and contractors). Since the pre-drilling campaign was completed, the Johan Sverdrup project has successfully tied back, completed and started production of the eight (8) pre-drilled oil producers and injection in the twelve (12) subsea injectors.

The sheer size of the 2.7-billion-barrel field and expected operations of more than 50 years, make Johan Sverdrup an exciting place to develop the solutions of the future. As such, the Johan Sverdrup field development has been called the digital flagship for the operator. Being a ‘flagship’ means Johan Sverdrup is not only meant to be a vehicle for digital innovation to improve safety, value-creation and carbon efficiency for the field itself, but the field development is also meant to drive digital solutions and ways of working that have the potential to be scaled-up for the benefit of the operator as a whole. This paper starts by setting out the main digital focus areas for the Johan Sverdrup development, but drills down on exploring the areas where Johan Sverdrup is demonstrating real and tangible impacts already today. Examples include efforts to mature technology for automatic production optimization, a number of new pipe and seabed technology solutions (including fiber-optic PRM, fiber-optic monitoring of wells), and the step-wise development of a digital twin for Johan Sverdrup that will gives the opportunity to model and visualize key parts of the field. The paper describes the ‘digital field-worker’ at Johan Sverdrup which is changing the way of working, both during the construction and completion phase, but also during operations. This ranges from efforts to automate and digitalize work processes offshore to more innovative solutions. Examples of the latter include Echo – a multi-player digital twin solution allowing real-time visualization and collaboration between onshore and offshore – as well as the iterative development of anomaly detection models (utilizing machine learning and artificial intelligence) to move from condition-based monitoring towards predictive maintenance.

In order to deliver on the ambitious schedule for the Johan Sverdrup development, the operator and the Johan Sverdrup-partners also needed to make some innovative bets on new technology. This paper explores two areas – innovations in installation and pipeline technology – that played a key role in the development of the mega-project. In particular the decision to qualify and become the world`s first user of the single-lift installation technology developed for the vessel Pioneering Spirit ended up changing the very concept for construction, installation and completion of three of the four topsides that make up the Johan Sverdrup field center in the first phase of the development. The technology – developed by the installation contractor and qualified for first use worldwide by the operator – saved an estimated 2.5 million offshore manhours from the offshore completion phase, which significantly reduced safety risks and helped shave months off the development schedule. The first-ever use of the technology to install topsides took place in June 2018 with the single-lift installation of the drilling platform topsides on the Johan Sverdrup field. And in March 2019, the two remaining topsides weighing a total of 44,000 tonnes were lifted in place in the span of only 3 days, including the heaviest offshore lift ever executed with the installation of the 26,500 tonnes processing platform. The paper also intends to explore how the same innovative mindset and focus also played a role in introducing new pipeline technology – in particular, the world`s first use of remote-controlled and diver-less hyperbaric welding of the ‘’36 oil export pipeline to the Johan Sverdrup riser platform. The paper also discusses how the project benefited from further industrialization of the hot-tapping technology used for the first time by the operator in 2012 on the Åsgard subsea project, when connecting the Johan Sverdrup gas export pipeline to the ‘live’ Statpipe gas pipeline. Part 1 of this paper covers single lift installation of topsides, Part 2 covers diver less hyperbaric welding.

As part of the operator's efforts to combat climate change going forward, the operator intends to reduce annual emissions from its oil and gas operations on the Norwegian Continental Shelf (NCS) by 40% within 2030, and to near zero by 2050. To achieve these emission reduction targets, the operator pursues energy efficiency measures, flaring elimination, electrification, floating offshore wind farms and other low-carbon solutions.Johan Sverdrup coming on stream plays a key role in the operator's ability to deliver on its international climate commitments. With recoverable resources of 2.7 billion barrels and a field lifetime of more than 50 years, identifying solutions for the Johan Sverdrup field development that minimize emissions from production was key to the concept selection process.The national regulatory and policy context in Norway also played a role. Norway was one of the first countries in the world to introduce a carbon tax, in 1991, and has been a member of the ‘cap and trade’ European Union Emissions Trading System (EU ETS) since 2008, which in effect puts a relatively steep price on carbon emissions from the petroleum sector. In addition, Norway's international climate commitments, with a target to reduce green-house gas emissions by 30% in 2020 relative to 1990 levels, also set clear expectations (even requirements for phase II of the development) for minimizing emissions from the Johan Sverdrup field. The result is a field with one of the lowest carbon emissions from production worldwide, with less than 1kg CO2 per barrel of oil equivalent produced.This paper starts by elaborating on the context and the strategic, regulatory and technical drivers for minimizing emissions from production from the Johan Sverdrup field. It then explores technologies and solutions chosen to minimize emissions – including, primarily, electrification by means of an HVDC (High Voltage Direct Current) power-from-shore solution but also energy-efficiency measures to optimize the utilization of the available power. The paper concludes by attempting to summarize lessons-learned of relevance for other oil and gas fields, also outside of the regulatory context of the Norwegian continental shelf.

In the same year that the Norwegian Continental Shelf (NCS) celebrates 50-years since the Ekofisk discovery in 1969, which in earnest established Norway as an oil and gas nation, the start-up of the Johan Sverdrup development will extend profitable oil and gas production with lower carbon emissions from the NCS for another five decades. The third largest oil field on the NCS, after the Ekofisk and Statfjord fields, and with recoverable reserves estimated at 2.7 billion barrels of oil equivalent, Johan Sverdrup certainly has the resources to be a North Sea giant. However, being a giant is more than having the necessary resources in place, it is also about turning these resources into recoverable reserves that can be produced in a safe, profitable and – increasingly in today's context – carbon efficient way. This paper provides a high-level summary of the experiences and lessons-learned from the development of the Johan Sverdrup field, and has the objective of serving as an introduction to the technical session papers that follow. As such, the paper aims to highlight what it took to make Johan Sverdrup a true North Sea giant, fit for the 21st century: a safe and successful execution of a mega-project, with next-generation facilities adapted to a more digital way of working, with an ambition to profitably recover more than 70% of the resources, while limiting carbon emissions from production to a minimum. The Johan Sverdrup development has set a new standard for project execution in Equinor, the paper concludes with lessons-learned of relevance for both Equinor's future project portfolio and projects globally.

The first phase of the giant Johan Sverdrup project started-up in October 2019, several months ahead of schedule, more than 30% under budget and with a very good safety record. This paper focuses on the execution of phase 1 of this mega-project – from the concept selection and engineering phase, to the global contracting strategy, through the construction across up to 30 building sites globally and until the end of the completions phase offshore Norway – attempting to explain what went well and why, and highlighting potential lessons of relevance to other offshore mega projects on the NCS and globally. Among other things, the paper looks at the impact of different variables in explaining the improvements made during the execution of the project – market effects, procurement strategies, scope optimization and execution performance. The paper then shows that while market effects played an important role – in part reflecting a project being sanctioned at the beginning of the recent oil and gas downturn – the true driver of the success of the project is found elsewhere. As phase II of the Johan Sverdrup development is already underway, the paper also looks at efforts made to sustain these drivers of success into the second phase of the project. The paper also describes which parts of the improvement journey that may not be necessarily replicable in the next stage of the megaproject.

Summary A dedicated seismic triple source was built and operated to acquire the seismic baseline of the Permanent Reservoir Monitoring (PRM) system of the Johan Sverdrup field in 2019. Operational experiences from this first seismic acquisition campaign will be shared. A quick insight of the impact on seismic data quality will also be presented.

Excess evaporation within the Persian (also referred as the Arabian) Gulf induces an inverse-estuary circulation. Surface waters are imported, via the Strait of Hormuz, while saltier waters are exported in the deeper layers. Using output of a 1/12-Degree horizontal resolution ocean general circulation model, the spatial structure and time variability of the circulation and the exchanges of volume and salt through the Strait of Hormuz are investigated in detail. The model’s circulation pattern in the Gulf is found to be in good agreement with observations and other studies based on numerical models. The mean export of salty waters in the bottom layer is of 0.26±0.05Sv (Sverdrup = 1.0 × 106 m3 s−1). The net freshwater import, the equivalent of the salt export divided by a reference salinity, done by the baroclinic circulation across that vertical section is decomposed in an overturning and a horizontal components, with mean values of 7.2±2.1 × 10−3 Sv and 5.0±1.7 × 10−3 Sv respectively. An important, novel finding of this work is that the horizontal component is confined to the deeper layers, mainly in the winter. It is also described for the first time that both components are correlated at the same level with the basin averaged evaporation minus precipitation (E-P) over the Persian Gulf. The highest correlation (r2 = 0.59) of the total freshwater transport across 26°N with E-P over the Gulf is found with a one-month time lag, with E-P leading. The time series of freshwater import does not show any significant trend in the period from 1980 to 2015. Power spectra analysis shows that most of the energy is concentrated in the seasonal cycle. Some intraseasonal variability, likely related to the Shamal wind phenomenon, and possible impacts of El-Nino are also detected. These results suggest that the overturning and the horizontal components of freshwater exchange across the Strait of Hormuz are both driven by dynamic and thermodynamic processes inside the Persian Gulf.

One of the main principles of improving oil recovery is maximizing the contact area between the well and the reservoir. To achieve this purpose especially in reservoirs with a thin oil column, long horizontal wells are widely used today. However, there are some challenges related to horizontal wells like water coning towards the heel due to the heel-toe effect as well as early water breakthrough owing to heterogeneity along the well. In order to tackle these issues, passive inflow control devices (ICDs) and autonomous inflow control devices (AICDs) can be used. ICDs are able to balance the drawdown pressure along the horizontal well and as a result, postpone the early water breakthrough. By applying AICDs, in addition to postponing the early water breakthrough, water can be partially choked back autonomously, and the negative impacts of early water breakthrough will be attenuated. The Johan Sverdrup field (JSF) is a giant oil field located in the North Sea and production from this field has been started recently. Since there is a plan for developing this oil field in the near future, and a few studies have been done on this field so far, further studies are needed to obtain more cost-effective oil recovery in this field. The main objective of this paper is the near-well simulation of oil production from the well 16/2-D-12 in the JSF by considering ICD and AICD completions. The simulation has been conducted based on the characteristics of the reservoir near this well for 750 days of oil production. OLGA in combination with ROCX has been used as a simulation tool. The simulation results showed that by applying both ICDs and AICDs the heel-toe effect, and heterogeneity along the well can be effectively handled and the water breakthrough time can be delayed by 255 days. Moreover, it was observed that by completion of the well 16/2-D-12 with AICDs, the accumulated water production can be reduced by 11.9% compared to using ICDs. In the same way, by using AICDs the flow rate of water production is reduced by 13.4% after 750 days. Furthermore, the results showed that using AICDs has a negligible impact on both the accumulated and the flow rate of oil production compared to using ICDs. Therefore, by completion of the well 16/2-D-12 with AICDs more cost-effective oil production can be achieved.

The global diapycnal transport in the ocean interior is one of the significant branches to return the deep water back toward near-surface. However, the amount of the diapycnal transport and the seasonal variations are not determined yet. This paper estimates the dissipation rate and the associated diapycnal transports at 500 m, 750 m and 1 000 m depth throughout the global ocean from the wide-spread Argo profiles, using the finescale parameterizations and classic advection-diffusion balance. The net upwelling is ~5.2±0.81 Sv (Sverdrup) which is approximately one fifth in magnitude of the formation of the deep water. The Southern Ocean is the major region with the upward diapycnal transport, while the downwelling emerges mainly in the northern North Atlantic. The upwelling in the Southern Ocean accounts for over 50% of the amount of the global summation. The seasonal cycle is obvious at 500 m and vanishes with depth, indicating the energy source at surface. The enhancement of diapycnal transport occurs at 1 000 m in the Southern Ocean, which is pertinent with the internal wave generation due to the interaction between the robust deep-reaching flows and the rough topography. Our estimates of the diapycnal transport in the ocean interior have implications for the closure of the oceanic energy budget and the understanding of global Meridional Overturning Circulation.

During the recent years, Indonesian government rapidly increase the electrification program which is mainly using coal energy. However, some areas are still need any supports of electricity. As an archipelagic state, Indonesia is surrounded by seas which is potential for developing the wave energy. Three areas were selected for examining the wave energy potential i.e., Meulaboh (in Sumatera), South Kuta (in Bali) and Manokwari (in Papua), which is the representative of the region in west, middle and east of Indonesia, respectively. Ocean wave characteristics were analyzed for each monsoon from 2012 to 2017, based on ocean wave forecasting using Sverdrup, Munk and Bretschneider method. The electrical power calculations were done by using Floating Oscillating Water Column formulas. Based on our analysis, the average of highest significant wave heights and periods in 3 sites happen in the West Monsoon and the lowest average of significant wave heights and periods mostly happen in the East Monsoon. Thus, among the three locations that were examined, South Kuta Bali is the best location to develop wave energy.

The meridional geostrophic transport (MGT) in the interior tropical North Pacific Ocean is estimated based on global ocean heat and salt content data. The decadal variations of the zonally and vertically integrated MGT in the tropical North Pacific Ocean are found to precede the Pacific decadal oscillation (PDO) by 1–3 years. The dynamics of the MGT are analyzed based on Sverdrup theory. It is found that the total meridional transport variability (MGT plus Ekman) is dominated by the MGT variability having positive correlations with the PDO index. The Sverdrup transports differ from the total meridional transport significantly and have insignificant correlations with PDO index, suggesting that the MGT variability is not controlled by the Sverdrup dynamics. In comparison, the simulated meridional transport variability in the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) and the Ocean General Circulation Model for the Earth Simulator are dominated by the Sverdrup transports, having insignificant correlations with the simulated PDO indices. The comparison suggests that the non-Sverdrup component in the MGT is important for the predictability of PDO and that significant deficiencies exist in these models in simulating a realistic structure of the tropical ocean gyre variability and predicting the decadal climate variations associated with it.

An ammonite-rich horizon was discovered in an otherwise rather unfossiliferous Albian succession in Kilen, North Greenland. It contains an assemblage with both gastroplitinid representatives of the Arctic Province and hoplitinid representatives of the European Province. Correlation between those provinces has been hampered by very little faunal overlap. Hence, the assemblage discovered in Kilen provides a rare and unique occurrence of a mixed assemblage. It allows for the correlation of the upper middle Albian Euhoplites lautus Zone to a level with Pseudogastroplites in Kilen, North Greenland, and acts as a step stone for further correlation with the fauna in the Sverdrup Basin.

The opening and pre-opening history of the Amerasia Basin is poorly constrained. Key tectonic events have been interpreted from outcrop data in adjacent sedimentary basins or from geophysical data along its continental margins. However, due to its location in a polar region, data are scarce and the existing models of tectonic evolution are controversial. The northernmost exposed adjacent basin is the Mississippian to Late Cretaceous Sverdrup Basin, the original structural framework of which is unclear because it was overprinted by the latest Cretaceous to Paleogene Eurekan Orogeny. This paper presents a restored structural cross-section of the eastern half of the Sverdrup Basin in order to remove deformation attributed to Eurekan shortening and identify previous Mississipian to Late Cretaceous structures. Our results reveal that the evolution of the Sverdrup Basin during the Mesozoic was dominated by the rising of salt diapirs in the basin centre and by Triassic to Jurassic extensional fault development at the basin’s margins. Diapirs were squeezed during Eurekan tectonic inversion whilst extensional faults formed thrusts. The discovery of Triassic fault activity is a new finding in the Sverdrup Basin and forms an extra element to be considered in tectonic models for the opening of the Amerasia Basin.

The upper Paleozoic (Carboniferous to Permian) succession of the Sverdrup Basin in the Canadian Arctic Islands has the potential to contain significant hydrocarbon reserves, though it has never been a primary exploration target. To better constrain previous estimates and hydrocarbon play possibilities, this study completed evaluations of source rock quality and extent and thermal maturity. This study also incorporated new understandings of reservoir units and their stratigraphic relation to source rocks, trapping configurations and timing of hydrocarbon migration. Several hydrocarbon source units were identified within the upper Paleozoic formations of the Sverdrup Basin including the Emma Fiord, Trappers Cove, Antoinette, Assistance, Sabine Bay, van Hauen and Trold Fiord formations. The Emma Fiord and Trold Fiord formations are both found to be oil prone, with the remainder of the sources being gas prone. The upper Paleozoic succession is interpreted to be gas prone due to dominant kerogen types and high average thermal maturity. Many of the older concept plays put forth for the upper Paleozoic succession have been determined to be unviable. However, modern plays that implement new understandings of the basin have the potential to be viable. This study has found that the upper Paleozoic succession of the Sverdrup Basin is promising for gas discoveries with new plays such as salt diapirism plays, or plays similar to the Barents Sea Gohta play. New hydrocarbon rock source data also suggests the potential for a new oil and gas play on northern Prince Patrick Island. This new research could lead to significant resource discoveries that have been previously overlooked.