Performance Monitoring on the A˚sgard “A” FPSO as Part of an Integrated Monitoring Strategy

2002 ◽  
Author(s):  
Arne So̸rli ◽  
Kyrre Langnes ◽  
Geert Laagland ◽  
Mike Hastings
Keyword(s):  
Monitoring System ◽  
Performance Monitoring ◽  
Early Stage ◽  
Integrated Monitoring ◽  
The North ◽  
Stage Of Development ◽  
System Supplier ◽  
The North Sea ◽  
Condition Monitoring System ◽  
One Year

An integrated machine condition monitoring system was developed, installed, tested, commissioned and successfully operated on a floating production, storage and offloading vessel (FPSO) in the North Sea. This system combines an existing vibration and process monitoring system with focused performance monitoring capability that has been implemented with the cooperation of the oil company end-user, a thermodynamics specialist consultant and a monitoring system supplier. Implementation of this integrated monitoring system strategy with advanced performance monitoring is partly based on the end-user’s requirements to optimize their operation and maintenance functions to improve competitiveness. The system has already been in use for one year and has demonstrated the ability to detect faults at an early stage of development, such as the compressor degradation and gas turbine fouling described in this paper. The same system has also been implemented in other oil & gas and power applications around the world with similar, positive results.

scholarly journals WAVE CLIMATE ANALYSIS FOR ENGINEERING PURPOSE

1976 ◽  
Vol 1 (15) ◽  
pp. 2 ◽  
Author(s):  
Hans H. Dette ◽  
Alfred Fuhrboter
Keyword(s):  
Wave Climate ◽  
Incoming Wave ◽  
Offshore Area ◽  
The North ◽  
Wave Measurements ◽  
Wind Velocities ◽  
Wave Heights ◽  
The North Sea ◽  
One Year ◽  
Climate Analysis

The North Sea (Fig. 1) is known as a random sea with depths in the southern part between 40 m and 100 m so that in contrary to the Atlantic and Pacific coastlines deep sea wave conditions do not exist. After four years of comprehensive wave measurements in the offshore area of the Island of Sylt near the Danish border a general analysis of the wave climate in that region was possible. In this paper results and suggestions will be presented under the aspect of replacing qualitative judgements by quantitative statements which are derived from the knowledge of the adjacent wave climate. Because the wave action varies from year to year a general time unit is not advisable for the evaluation of shore processes; therefore the time scale should be substituted by the integral of incoming wave energy occurring after a certain time. The investigated method of expressing the total energy of one season or one year in the electrical unit Kilowatthour (kWh) per meter (m) width of shoreline could prove in future as a feasible way of classifying the irregular seasonal and yearly wave intensities. It is further shown that wave measurements over a period of several years can be sufficient for the investigation of correlations between the wind velocities occurring from all directions and the resulting wave heights. In case of satisfying correlation factors it will then be possible to carry out feedback operations for periods from which only records of wind velocities and directions are available and even to hindcast the wave heights for certain not yet measured wind velocities.

Validation and interpretation of data obtained by the newly developed low-cost Geodetic Integrated Monitoring System (GIMS)

2020 ◽  
Author(s):  
Ela Šegina ◽  
Mateja Jemec Auflič ◽  
Tina Peternel ◽  
Matija Zupan ◽  
Jernej Jež ◽  
...  
Keyword(s):  
Monitoring System ◽  
Low Cost ◽  
Warning System ◽  
Threshold Value ◽  
Rainfall Threshold ◽  
Rain Gauge ◽  
Measuring System ◽  
Integrated Monitoring ◽  
The North ◽  
The Wire

<p>Geodetic Integrated Monitoring System (GIMS) has been developed as a low-cost solution for detecting and measuring ground movements (https://www.gims-project.eu/). The prototype has been tested on the landslide on Potoška planina in the north of Slovenia that has been monitored by the seven GIMS units. These units, consisting of GNSS receiver and inclinometer, provide live monitoring data with millimetric precision. In this paper, the project consortium presents the first results of the prototype measuring system and estimate its applicability in modern landslides monitoring. The GIMS measurements have been validated by the wire crackmeter located at the site. The data were correlated to the groundwater level in a piezometer and to the amount of precipitation detected at the rain gauge. Results of GIMS units show good comparability to the wire crackmeter measurements and increased precision in detecting variations in landslide movements. The latter enables us to precisely define the rainfall threshold value for the particular landslide as crucial information needed for a reliable early warning system.</p><p> </p>

Long-term monitoring of coastal saltwater intrusion using the geoelectrical monitoring system SAMOS

2021 ◽  
Author(s):  
Michael Grinat ◽  
Mathias Ronczka ◽  
Thomas Günther ◽  
Dieter Epping ◽  
Vitali Kipke ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Monitoring System ◽  
North Sea ◽  
Early Warning ◽  
Groundwater System ◽  
Transition Zones ◽  
The North ◽  
The North Sea ◽  
Local Water

<p>Efficient groundwater management is the key to a sustainable use of freshwater aquifers. In the coastal areas worldwide, saltwater intrusions caused by sea-level rise, overuse of freshwater resources and changing groundwater recharge is a major threat to the availability of freshwater. A reduced groundwater recharge combined with an increased extraction can lead to vertical upconing or lateral movement of the freshwater-saltwater transition zones, therefore reducing the local freshwater resources. Long-term and continuous observation of the freshwater-saltwater transition zones is crucial to implement early warning procedures, yields more detailed insight into the groundwater system and therefore enables early adjustment and adaptation of extraction rates if needed.</p><p>The SAltwater MOnitoring System (SAMOS) consists of two main parts: a vertical electrode chain of steel ring electrodes permanently installed in a backfilled borehole and a measuring system at the surface. The number of electrodes (commonly about 80) and distance between adjacent electrodes (commonly about 25 cm) is generally flexible. The chain of electrodes is connected to a lightweight and small resistivity meter (LGM, 4-Point light 10W). Thanks to the maximum output current of 100 mA and a voltage of 380 V a low power consumption is achieved and long-term and autonomous monitoring is enabled by solar panel based power supply. Furthermore, the system is designed to run predefined measurement protocols and transfers the data to a remote server immediately after a measurement is performed. SAMOS is commonly installed in the transition zone between fresh- and saltwater allowing the detection of very slight resistivity changes (less than 1 Ohmmeter). While first systems were completely manufactured by LIAG, the latest subsurface systems were built by Solexperts which allowed us to include temperature sensors.</p><p>We present data from four SAMOS systems currently running at different locations. Two of them are installed in the central part of the freshwater lense of the North Sea island Borkum (in cooperation with Stadtwerke Borkum) in depths between 44 m and 65 m below the surface, close to freshwater wells of the local water supplier, thus monitoring the overall groundwater system and delivering data since 2009. Even though measurements immediately after the installation are disturbed by the drilling process and an adjustment to undisturbed natural conditions is observed, adapted inversion schemes allow to use all data. While in most cases only slight resistivity changes are observed up to now, at some depths larger seasonal resistivity changes occur at one Borkum site that can mostly be explained by changes of the groundwater recharge rate and changing pumping activities in a water catchment area. Two further systems have been installed in 2018 and 2020. One is located behind the dune line at the edge of the freshwater lense on the North Sea island Spiekeroog. In cooperation with the local water supply company OOWV (Oldenburg-Ostfriesischer Wasserverband) another system for their groundwater extraction fields is installed near Jever several kilometers from the coast-line used for early warning.</p>

Significant Reduction of Well System Fatigue by Use of Reactive Flex Joint with Integrated Monitoring System

2021 ◽  
Author(s):  
Knut Olav Sønåsen ◽  
Per Thomas Moe ◽  
Morten Hansen ◽  
Dag André Fjeldstad ◽  
Halvor Gustad ◽  
...  
Keyword(s):  
Real Time ◽  
Monitoring System ◽  
Barents Sea ◽  
Bending Moment ◽  
Bending Moments ◽  
Time Data ◽  
Integrated Monitoring ◽  
Cyclic Bending ◽  
Operational Conditions ◽  
The North

Abstract Operators working on shallow and mid-water depths in rough seas are focusing on reducing fatigue in the upper part of well systems during drilling operations. Fatigue is caused by cyclic bending moments due to wave induced riser and vessel motions. The combined use of a Reactive Flex-Joint (RFJ) and the Well Access Management System (WAMS) has demonstrated significantly reduced fatigue exposure through a reduction in loads, reporting of real-time status and rig positioning advice. The RFJ is a mechanism mounted on a standard flex joint for easy installation on drilling rigs. It uses a nitrogen gas spring to reverse the flex joint bending moment. The generated opposing moment increases with an increasing angle of the lower flex joint. This significantly reduces the cyclic bending moments in the lower part of the Blow Out Preventer (BOP) and wellhead (WH) system. WAMS is an advanced monitoring system that may be operated as a fully integrated part of the RFJ design. Sensors provide real-time data for flex joint angle, BOP inclination, wellhead- and riser bending moments. The data is used to assess incurring fatigue damage in real-time and for reporting fatigue status after operations. Two RFJ systems have been in continuous use on two separate rigs during 2020. The RFJ system and WAMS are field-proven and have demonstrated their efficiency in challenging operations in the Barents Sea and the North Sea. The RFJ has been well received in the market due to one-time installation, safe use, significant reduction in wellhead loads, and low operating expenses (OPEX). Data obtained from the operations have been carefully analyzed and show that the RFJ reduces cyclic loads from 50 to 80% resulting in 30 to as much as 1000 times extended fatigue life of the wellhead. The RFJ efficiency depends on the settings of the system and operational conditions.

scholarly journals Evaluation of the quality of the North Sea herring assessment

2009 ◽  
Vol 66 (8) ◽  
pp. 1814-1822 ◽  
Author(s):  
E. John Simmonds
Keyword(s):  
North Sea ◽  
Management Strategy ◽  
Fishing Mortality ◽  
The North ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The North Sea ◽  
Acoustic Surveys ◽  
One Year

Abstract Simmonds, E. J. 2009. Evaluation of the quality of the North Sea herring assessment. – ICES Journal of Marine Science, 66: 1814–1822. The assessment of North Sea herring has been used to give advice on catch quota for more than 20 years. The data sources comprise acoustic surveys, International Bottom Trawl Surveys, Methot Isaacs–Kidd net post-larval surveys, larval surveys, and catch-at-age data. These sources and their uses are briefly reviewed, and the changes in the weighting attached to each index in the assessment over time are discussed. The performance of the assessment is examined both in historical and analytical retrospectives of spawning–stock biomass and fishing mortality, and in retrospective assessments of numbers by cohort. Increased length of the time-series, the use of a statistical model with appropriate weighting, and a more consistent management strategy have all contributed to the assessment becoming highly stable from one year to the next. The results presented lead to the conclusion that the assessments provide an excellent basis for the management of this stock.

scholarly journals Realized habitats of early-stage North Sea herring: looking for signals of environmental change

2010 ◽  
Vol 68 (3) ◽  
pp. 537-546 ◽  
Author(s):  
Christine Röckmann ◽  
Mark Dickey-Collas ◽  
Mark R. Payne ◽  
Ralf van Hal
Keyword(s):  
Time Series ◽  
Environmental Change ◽  
North Sea ◽  
Early Stage ◽  
Interannual Variations ◽  
The Past ◽  
The North ◽  
The North Sea ◽  
Juvenile Stages ◽  
Newly Hatched Larvae

Abstract Röckmann, C., Dickey-Collas, M., Payne, M. R., and van Hal, R. 2011. Realized habitats of early-stage North Sea herring: looking for signals of environmental change. – ICES Journal of Marine Science, 68: . Realized habitats of North Sea herring for two larval and two juvenile stages were estimated over the past 30 years, using abundances from surveys tied to modelled estimates of temperature and salinity. Newly hatched larvae (NHL) were found mainly in water masses of 9–11°C, pre-metamorphosis larvae (PML) around 5–6°C, juveniles aged 0 in summer around 13–14°C, and juveniles aged 1 in winter around 4–5°C. The median salinity in which the NHL were distributed was 34.4–35.0 and 33.7–33.9, respectively, for PML and juveniles. Interannual variations in temperature and geographic variables in the North Sea were compared with the time-series of realized habitats. The realized temperature habitats of the NHL did not change over time, but the habitat of juveniles in summer may be associated with higher temperatures. Juveniles aged 1 in winter are found in waters colder than the average for the North Sea, a result also reflected in their geographic shift east into shallower water. The results suggest that juveniles could be limited by temperature, but may also track changes in food or predator distribution, and/or internal population dynamics. Time-series analysis of realized salinity habitats was not possible with the available data because of differences between model outputs.

scholarly journals The role of heat wave events on the occurrence and persistence of thermal stratification in the southern North Sea

2022 ◽  
Author(s):  
Wei Chen ◽  
Joanna Staneva ◽  
Sebastian Grayek ◽  
Johannes Schulz-Stellenfleth ◽  
Jens Greinert
Keyword(s):  
Potential Energy ◽  
Water Column ◽  
Heat Wave ◽  
North Sea ◽  
Thermal Stratification ◽  
Early Stage ◽  
Southern North Sea ◽  
The North ◽  
The North Sea

Abstract. Extremes in temperatures not only directly affect the marine environment and ecosystems but also have indirect impacts on hydrodynamics and marine life. The role of heat wave events responsible for the occurrence and persistence of thermal stratification was analysed using a fully coupled hydrodynamic and wave model within the framework of the Geesthacht Coupled cOAstal model SysTem (GCOAST) for the North Sea. The model results were assessed against satellite reprocessed data and in situ observations from field campaigns and fixed MARNET stations. To quantify the degree of stratification, a potential energy anomaly over the water column was calculated. A linear correlation existed between the air temperatures and the potential energy anomaly in the North Sea excluding the Norwegian Trench and the area south of 54° N latitude. Contrary to the northern part of the North Sea, where the water column is stratified in the warming season each year, the southern North Sea is seasonally stratified in years when a heatwave occurs. The influences of heatwaves on the occurrence of summer stratifications in the southern North Sea are mainly in the form of two aspects, i.e., a rapid rise in sea surface temperature at the early stage of the heatwave period and a relatively higher water temperature during summer than the multiyear mean. Another factor that enhances the thermal stratification in summer is the memory of the water column to cold spells earlier in the year. Differences between the seasonally stratified northern North Sea and the heatwave-induced stratified southern North Sea were attributed to changes in water depth.

Reproductive biology of three caridean shrimp, Rimicaris exoculata, Chorocaris chacei and Mirocaris fortunata (Caridea: Decapoda), from hydrothermal vents

2000 ◽  
Vol 80 (3) ◽  
pp. 473-484 ◽  
Author(s):  
Eva Ramirez Llodra ◽  
Paul A. Tyler ◽  
Jonathan T.P. Copley
Keyword(s):  
Hydrothermal Vents ◽  
Early Stage ◽  
Population Level ◽  
Maximum Size ◽  
Caridean Shrimp ◽  
Rimicaris Exoculata ◽  
North East ◽  
The North ◽  
Stage Of Development ◽  
Gravid Females

The caridean shrimp Rimicaris exoculata, Chorocaris chacei and Mirocaris fortunata, together with bathymodiolid mussels, dominate the vent fauna along the Mid-Atlantic Ridge. Vent shrimp show the characteristic reproductive patterns of caridean decapods. The gonads are paired organs overlying the digestive gland under the carapace. In the ovaries, the oogonia (∼20-30 μm diameter) proliferate in the germinal epithelium at the periphery of the gonad, developing into previtellogenic oocytes. The previtellogenic oocytes grow to 70-100 μm before undergoing vitellogenesis. The maximum size for mature oocytes ranged between 200 and 500 μm depending on the species and the sample. The oocyte size–frequency data show no evidence of synchrony in oogenesis at population level for any of the species studied. Mirocaris fortunata is the only species where gravid females are commonly collected. The brood is carried on the pleopods, and the number of eggs per female ranges from 25 to 503, with a mean egg length of 0.79±0.14 mm. There is a positive correlation between fecundity and body size, characteristic of crustaceans. One ovigerous C. chacei and two R.exoculata have been studied. The former was carrying 2510 eggs and the later 988 small eggs in an early stage of development. The fecundity of M. fortunata, C. chacei and R. exoculata is significantly higher than that of species from the Acanthephyra group collected in the north-east Atlantic.

Parallel-route Systems for Supersonic Traffic

1966 ◽  
Vol 19 (3) ◽  
pp. 348-360
Author(s):  
V. W. Attwooll
Keyword(s):  
Traffic Control ◽  
Early Stage ◽  
Aircraft Design ◽  
Supersonic Transport ◽  
Traffic System ◽  
The North ◽  
Stage Of Development ◽  
Mode Of Operation ◽  
Traffic Systems ◽  
The Cost

This is the third article of a series of three describing the methods developed at the Royal Aircraft Establishment for costing the effect of air traffic control deviations in long range systems. The first two discussed the general principles of costing and their application to the current and future systems for subsonic aircraft over the North Atlantic. The present paper considers systems for the S.S.T.The characteristics and mode of operation of the supersonic transport are untested, and it will operate at an altitude for which information is relatively scanty. This means that the results obtained for the cost penalties in a supersonic traffic system must be regarded as tentative. On the other hand, because we are considering traffic systems for aircraft at such an early stage of development, the situation can be analysed in a more fundamental way, with particular emphasis on the effect of the system on the aircraft design.

Sign in / Sign up

Export Citation Format

Share Document