Drift-Off Study in Drilling Vessels Comparing Numerical Model and Full-Scale Field Measurements

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Eduardo A. Tannuri ◽  
Pedro C. de Mello ◽  
Raul Dotta ◽  
Anderson T. Oshiro ◽  
Gustavo R. Diederichs ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Environmental Conditions ◽  
Emergency Situation ◽  
Field Measurements ◽  
Full Scale ◽  
Large Set ◽  
System Failures ◽  
Environmental Disasters ◽  
Drift Trajectory

Abstract In drilling vessels, the dynamic positioning (DP) system has a great importance for the operation, since it ensures the station-keeping ability for the drilling operation. However, an emergency situation involves ungoverned drift due to problems associated with the DP system failures, such as thrusters, generators, powerbus, or control system. During this situation, the vessel drift is subjected to the influence of environmental conditions and the drift can lead to collisions with floating obstacles or submerged systems, wellhead emergency disconnection, damage to equipment and potentially causing major environmental disasters. It is then necessary to define a safety region for the drilling ship operation and to determine the limiting operation offset that the drilling vessel can disconnect from the wellhead without damage to any equipment. This offset limit is obtained through a riser analysis and drift-off study, important inputs for the Well Specific Operating Guidelines (WSOG). A validated time-domain simulator is required and able to predict the vessel drift trajectory after the DP failure under several environmental conditions. The aim of this work is to present a large set of model and full-scale drift tests and the validation of a time-domain numerical simulator (Dynasim), based on the main parameters of the drift tests: drift distance, heading variation, and trajectory. The comparisons between the numerical simulation results with full- and model-scale data demonstrated the accuracy of the numerical model, confirming that the simulator is a reliable tool to predict the motion of a drilling vessel after a blackout.

Validation of Numerical Models for the Drift-Off Study in Drilling Vessels Using Full Scale Measurements

2018 ◽  
Author(s):  
Raul Dotta ◽  
Eduardo A. Tannuri ◽  
Pedro C. de Mello ◽  
Gustavo R. Diederichs ◽  
Daniel F. Cruz ◽  
...  
Keyword(s):  
Numerical Model ◽  
Environmental Conditions ◽  
Numerical Models ◽  
Emergency Situation ◽  
Full Scale ◽  
System Failures ◽  
Environmental Disasters ◽  
Important Input ◽  
Definition Of ◽  
Full Scale Tests

In drilling vessels, the dynamic positioning (DP) system has great importance for the operation, since it ensures the station keeping ability for carrying out the drilling operation. However, an emergency situation involves ungoverned drift due to problems associated with the DP system failures, such as thrusters, generators, powerbus or control system. During this emergency situation, the vessel drift is subjected to the influence of environmental conditions and the drift can lead to collisions with floating obstacles or submerged systems, wellhead emergency disconnection, damage to equipments and potentially causing major environmental disasters. Due to the possible occurrence of this emergency condition, it is necessary to define a safety region for the drilling ship operation and to determine the limiting operation offset that the drilling vessel can disconnect from the wellhead without damage to any equipment. This limit offset is obtained through a riser analysis and drift-off study, being an important input for WSOG (Well Specific Operating Guidelines). The study will provide vessel drift trajectory after the DP failure under several environmental conditions. A validated time domain simulator must be used for obtaining such data. In the present work, the Dynasim software, developed from the partnership between Petrobras and Brazilian universities, is applied. Thus, the aim of this work is to validate the Dynasim numerical model using drift data from full scale tests performed on vessels operated by Petrobras and under several environmental conditions. For the validation and calibration of the numerical model, three main parameters were compared: distance time-series, heading variation and trajectory during the drift of the vessel. The comparisons between full scale data and numerical simulation results demonstrated the accuracy of the numerical model. Therefore, the application of this tool provides a valuable contribution to the reliability of WSOG analysis, planning of the operations, allowing the determination of the drift path in relation to the wind, current and waves, and the definition of drift maps and establishing safety zones for the drilling vessel operation, minimizing the risk of collisions.

Experimental and Numerical Modelling of an Offshore Aquaculture Cage for Open Ocean Waters

2018 ◽  
Author(s):  
Alfonso Jurado ◽  
Patricia Sánchez ◽  
Jose A. Armesto ◽  
Raúl Guanche ◽  
Bárbara Ondiviela ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Environmental Conditions ◽  
Ad Hoc ◽  
Experimental Tests ◽  
Ocean Basin ◽  
Open Ocean ◽  
Offshore Aquaculture ◽  
Decay Tests ◽  
Multi Body

An innovative offshore aquaculture cage design and its hydrodynamic behavior for different environmental conditions is presented. The work involves the following blocks: (i) design of the aquaculture cage, (ii) experimental tests performed at IHCantabria facilities (Cantabria Coastal and Ocean Basin, CCOB), (iii) brief description of the ad-hoc time domain numerical model developed, and (iv) calibration of decay tests and sea states cases, in order to be able to simulate different locations of interest for aquaculture stakeholders. The offshore aquaculture cage is a floating cylindrical structure, designed according to different requirements from standards and needs of contacted aquaculture stakeholders. The cage is focused on the growing and farming of fish species in open ocean conditions. It has been specially designed to be able to withstand different environmental conditions, even waves of more than 5m height. Through numerical and physical modeling, it has been shown that it has a good seakeeping and accessibility, to reduce O&M costs. Motions and loads have been registered during the tank testing to calibrate and validate a specific coupled time domain numerical model developed for multi-body structures to simulate the behavior of the assembled structure (cage and sinker connected by tendons), including non-linear damping forces and a FEM approach to model the mooring and the tendon system.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

Calibration of a Time-Domain Hydrodynamic Model for A 12 MW Semi-Submersible Floating Wind Turbine

2021 ◽  
Author(s):  
Carlos Eduardo Silva de Souza ◽  
Nuno Fonseca ◽  
Petter Andreas Berthelsen ◽  
Maxime Thys
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Time Domain ◽  
Quadratic Model ◽  
Wave Loads ◽  
Frequency Wave ◽  
Load Models ◽  
Wave Drift ◽  
Floating Wind Turbine ◽  
Decay Tests

Abstract Design optimization of mooring systems is an important step towards the reduction of costs for the floating wind turbine (FWT) industry. Accurate prediction of slowly-varying horizontal motions is needed, but there are still questions regarding the most adequate models for low-frequency wave excitation, and damping, for typical FWT concepts. To fill this gap, it is fundamental to compare existing load models against model tests results. This paper describes a calibration procedure for a three-columns semi-submersible FWT, based on adjustment of a time-domain numerical model to experimental results in decay tests, and tests in waves. First, the numerical model and underlying assumptions are introduced. The model is then validated against experimental data, such that the adequate load models are chosen and adjusted. In this step, Newman’s approximation is adopted for the second-order wave loads, using wave drift coefficients obtained from the experiments. Calm-water viscous damping is represented as a linear and quadratic model, and adjusted based on decay tests. Additional damping from waves is then adjusted for each sea state, consisting of a combination of a wave drift damping component, and one component with viscous nature. Finally, a parameterization procedure is proposed for generalizing the results to sea states not considered in the tests.

Experimentally calibrated simplified time-domain numerical model for a multi-chamber OWC device

2015 ◽  
pp. 463-469
Author(s):  
A Iturrioz ◽  
J Sarmiento ◽  
J Armesto ◽  
R Guanche ◽  
C Vidal ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain

scholarly journals A COMPARISON BETWEEN MODEL AND PROTOTYPE WAVES IN HARBOURS

1978 ◽  
Vol 1 (16) ◽  
pp. 38
Author(s):  
Sverre Bjordal ◽  
Alf Torum
Keyword(s):  
Physical Model ◽  
Model Test ◽  
Field Measurements ◽  
Full Scale ◽  
Common Method ◽  
Test Results ◽  
Open Coast ◽  
The World ◽  
Mooring Forces ◽  
Absolute Basis

A common method of estimating the sheltering effects of different breakwater locations and layouts is to carry out physical model wave disturbance tests. Such tests have been carried out in different laboratories throughout the world for many years. But to our knowledge no reports are available in the literature showing comparison between model measurements and field measurements. The trend is that we know more and more on the wave cl imate along our coasts. Hence we have a better basis to make our economical calculations on breakwaters. We therefore also want to operate our models on a more absolute basis rather than on a comparative basis. The trend in recent years has also been to study breakwater locations and layouts in order to minimize mooring forces and ship movements. On this background VHL found a comparison between model test results and field measurements necessary. Full scale measurements of waves were carried out in two harbours by VHL during the winter 1976/77. This paper will present the results of the comparison of the model and the full scale measurements in Berlevag and Vard0 fishing harbours on the open coast of Finnmark in the northern part of Norway (Fig. I) . The model tests, as well as the full scale measurements, have been sponsored by the Norwegian State Harbour Authorities.

scholarly journals Megasource time-domain electromagnetic sounding at Poggi del Sasso - Cinigiano (GR)

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
G. V. Keller ◽  
P. Cantini ◽  
R. Carrara ◽  
O. Faggioni ◽  
E. Pinna
Keyword(s):  
Depth Profile ◽  
Time Domain ◽  
Environmental Conditions ◽  
Dipole Source ◽  
Electromagnetic Noise ◽  
Electromagnetic Sounding ◽  
Piecewise Constant ◽  
Time Domain Electromagnetic ◽  
The Time Domain ◽  
Single Set

An experiment was carried out in the vicinity of the “I Terzi” area in Southeastern Tuscany (fig. 1) to evaluate the applicability of the Time Domain Electromagnetic (TDEM) sounding method under the geological and environmental conditions prevailing in that area. An electromagnetic source was established using a motor-generator set and heavy cable. Measurements were attempted at four sites. Numerous samples of electromagnetic noise were recorded at each of these sites. At one site, signals transmitted for a grounded dipole source at 1.6 km distance were also recorded with the noise. The single set of observations has been processed and inverted to yield a six-layer piecewise constant resistivity depth-profile to a depth of about 2 km. The primary achievement of the experiment was demonstration of the praeticability of TDEM methods under the conditions prevailing in the site.

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