Oil Spill Model Operational Application in Damage Assessment and Case Study of Validation

Oil spill modeling is an important technical measure to evaluate the impact of oil spills scientifically. Because of the great uncertainty in its early development, simulation results have not been used as the basis of judgments for environmental compensation cases. Despite this, scientific research institutes in many countries, including China, are still devoted to the research and development of oil spill models and their applications in environmental damage assessment, which makes it possible to apply them in the judicial arbitration of damages claims. The relevant regulations on the Chinese compensation fund for oil pollution damage from ships and the judicial authentication of environmental damage have also accredited such kind of modeling applications. In order to enhance the applicability of oil spill model further, it is necessary to expand its damage assessment function, and to test, calibrate and verify the accuracy of the evaluation. To this end, the author adopts the self-developed 3-dimentionaloil spill model—CWCM to simulate the “Tasman Sea” oil spill accident. By comparing the simulation results of tidal current field, wind field, oil spill trajectory with those observed, the model coding and parameter selection are corrected, and it is realized that the simulation being basically consistent with the measured results. In addition, the results of the scale reduced simulation test of oil spill weathering are applied verifying and perfecting the weathering model of CWCM. The technical requirements and process for operational application of oil spill model in judicial arbitration are also put forward. In view of the rapid simulation function, the operational updating program for oil spill weathering model, coupled current model and dynamic update wind field diagnostic model are put forward in order to further improve the operational evaluation function and evaluation efficiency of oil spill model.

Lagrangian Model PETROMAR-3D to Describe Complex Processes in Marine Oil Spills

The version 2.1 of PETROMAR-3D model, created in the Center for Marine Meteorology of the Meteorology Institute of Cuba, is presented. This Lagrangian model has been designed to describe the physical processes of marine oil spills in the face of multiple scenarios of the marine environment. Although it is applicable to any part of the world, it is mainly designed for inter-American seas. The novelty has been to integrate the processes of drift and weathering into a model, with updated methods that incorporate 3D phenomena, a very favorable situation to achieve an operating system in Cuba and the region for the immediate and medium term. Python was chosen as the programming language because it has advanced libraries for numerical modeling, automation work and other useful tools for pre-and post-processing. By means of adapters, an important number of atmospheric, hydrodynamic and wave models have been considered to create the scenarios efficiently. The modular distribution in which the code has been created facilitates its use for other dispersion analysis and biophysical applications. Finally, a set of simple images are presented, aimed at informing decision-makers in order to mitigate the effects of the spill on the environment.

Probabilistic Modeling of Oil Spills at the Exclusive Economic Zone of Cuba Using Petromar-3D Model

This article shows the probabilistic modeling of hydrocarbon spills on the surface of the sea, using climatology data of oil spill trajectories yielded by applying the lagrangian model PETROMAR-3D. To achieve this goal, several computing and statistical tools were used to develop the probabilistic modeling solution based in the methodology of Guo. Solution was implemented using a databases approach and SQL language. A case study is presented which is based on a hypothetical spill in a location inside the Exclusive Economic Zone of Cuba. Important outputs and products of probabilistic modeling were obtained, which are very useful for decision-makers and operators in charge to face oil spill accidents and prepare contingency plans to minimize its effects. In order to study the relationship between the initial trajectory and the arrival of hydrocarbons spills to the coast, a new approach is introduced as an incoming perspective for modeling. It consists in storage in databases the direction of movement of the oil slick at the first 24 hours. The probabilistic modeling solution presented is of great importance for hazard studies of oil spills in Cuban coastal areas.

Modelling of the behavior of marine oil spills: applications based on random walk techniques

A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.

i4OilS pill, an Operational Marine Oil Spill Forecasting Model for Bohai Sea

Oil spill models can effectively simulate the trajectories and fate of oil slicks, which is an essential element in contingency planning and effective response strategies prepared for oil spill accidents. However, when applied to offshore areas such as the Bohai Sea, the trajectories and fate of oil slicks would be affected by time-varying factors in a regional scale, which are assumed to be constant in most of the present models. In fact, these factors in offshore regions show much more variation over time than in the deep sea, due to offshore bathymetric and climatic characteristics. In this paper, the challenge of parameterizing these offshore factors is tackled. The remote sensing data of the region are used to analyze the modification of wind-induced drift factors, and a well-suited solution is established in parameter correction mechanism for oil spill models. The novelty of the algorithm is the self-adaptive modification mechanism of the drift factors derived from the remote sensing data for the targeted sea region, in respect to empirical constants in the present models. Considering this situation, a new regional oil spill model(i4Oil Spill) for the Bohai Sea is developed, which can simulate oil transformation and fate processes by Eulerian-Lagrangian methodology. The forecasting accuracy of the proposed model is proven by the validation results in the comparison between model simulation and subsequent satellite observations on the Penglai 19-3 oil spill accident. The performance of the model parameter correction mechanism is evaluated by comparing with the real spilled oil position extracted from ASAR images.

Oil Spill Dispersion Forecasting with the Aid of a 3D Simulation Model

The simulation of the transport and fate of an oil slick, accidentally introduced in the marine environment, is the focus of this research. An oil spill dispersion forecasting system （DIAVLOS forecasting system）, based on wind, wave and ocean circulation forecasting models is developed. The 3-D oil spill model, by the University of Thessaloniki, is based on a Lagrangian （tracer） model that accounts for the transport-diffusion-dispersion and physicochemical evolution of an oil slick. The high resolution meteorological, hydrodynamic and wave models are coupled with the operational systems ALERMO and SKIRON of the University of Athens. The modelling system was successfully assembled and tested under theoretical and realistic scenarios, in order to be applied in forecasting mode and be used by local authorities when an accident occurs. As a result, a 48-hours oil spill dispersion forecasting system was synthesized aiming primarily at the oil spill management at the Burgas-Alexandroupolis oil-pipe terminal, part of a greater busy coastal basin in North Aegean.

A Three-dimensional Forecasting Model for Oil Spill

A 3-D forecasting model for oil-spill is developed using the finite difference method to numerically solve the shallow water equation. The instantaneous flow distribution in the studied area is calculated and the trajectory of the oil-slick centroid is predicted by means of Lagrange’s method. The computed results agree with the observed data well, this shows that this 3-D forecasting model has high accuracy.

Modeling an Oil Spill along the Southern Brazilian Shelf: Forcing Characterization and Its Influence on the Oil Fate

Oil spills can generate multiple effects in different time scales on the marine ecosystem. The numerical modeling of these processes is an important tool with low computational cost which provides a powerful appliance to environmental agencies regarding the risk management. In this way, the objective of this work is to evaluate the influence of a number of physical forcing acting over a hypothetical oil spill along the Southern Brazilian Shelf. The numerical simulation was carried out using the ECOS model (Easy Coupling Oil System), an oil spill model developed at the Universidade Federal do Rio Grande—FURG, coupled with the tridimensional hydrodynamic model TELEMAC3D (EDF, France). The hydrodynamic model provides the current velocity, salinity and temperature fields used by the oil spill model to evaluate the behavior and the fate of the spilled oil. The results suggest that the local wind influence is the main forcing driven the fate of the spilled oil, and this forcing responds for more than 60% of the oil slick variability. The direction and intensity of the costal currents control between 20% and 40% of the oil variability, and the currents are important controlling the behavior and the tridimensional transportation of the oil. On the other hand, the turbulent diffusion is important for the horizontal drift of the oil. The weathering results indicate 40% of evaporation and 80% of emulsification, and the combination of these processes leads an increasing of the oil density around, 53.4 kg/m3 after 5 days of simulation.

The influence of Stokes drift on oil spills:Sanchi oil spill case

Spilled oil floats and travels across the water’s surface under the influence of wind,currents,and wave action.Wave-induced Stokes drift is an important physical process that can affect surface water particles but that is currently absent from oil spill analyses.In this study,two methods are applied to determine the velocity of Stokes drift,the first calculates velocity from the wind-related formula based upon a one-dimensional frequency spectrum,while the second determines velocity directly from the wave model that was based on a twodimensional spectrum.The experimental results of numerous models indicated that:(1)oil simulations that include the influence of Stokes drift are more accurate than that those do not;(2)for medium and long-term simulations longer than two days or more,Stokes drift is a significant factor that should not be ignored,and its magnitude can reach about 2%of the wind speed;(3)the velocity of Stokes drift is related to the wind but is not linear.Therefore,Stokes drift cannot simply be replaced or substituted by simply increasing the wind drift factor,which can cause errors in oil spill projections;(4)the Stokes drift velocity obtained from the two-dimensional wave spectrum makes the oil spill simulation more accurate.

Flammability risk assessment for oil spill response operations

Immediately following a spill at sea, released oil ranging from diesel to light crude and diluted bitumen, will initially weather through evaporation, resulting in an elevated concentration of light hydrocarbons in the air. As part of oil spill response operations, first responders use hand-held devices to monitor airborne concent- rations when approaching a spill. The feasibility of using numerical modelling as an additional tool to assess potential flammability and plan response operations in the spill area was explored in this study. The Lower Explosive Limit (LEL) is defined as the minimum concentration of a gas in air, in this case a mixture of evaporated hydrocarbons, which can produce a flash fire in the presence of an ignition source. This ignition source could be triggered by the vessel itself or by spill response operations. A framework was put into place, utilizing a three- dimensional hydrodynamic model (H3D), an oil spill model (SPILLCALC), and an air dispersion model (CALPUFF) to assess the risk of possible ignition of the hydrocarbon vapour in the event of a spill. The study looked at a hypothetical credible worst case tanker spill (16 500 m3) of diluted bitumen (cold lake winter blend) occurring at Arachne Reef in Haro Strait, British Columbia, Canada. SPILLCALC provided one-minute averaged vapour fluxes from the water surface for each of 17 modelled pseudo-components which were used as inputs to CALPUFF. Using the predicted airborne concentrations of each pseudo-component, time-scaled to one-second averages, the flammability potential in the immediate spill area was determined at each grid point using Le Chatelier’s mixing equation. The approach describe here was developed as a proof of concept, and could be established as a real-time system, bringing valuable information in addition to hand-held devices during a spill response, or during a response exercise. This modelling study was conducted as part of Kinder Morgan’s Trans Mountain Pipeline Expansion Project. There are a number of commercially available oil spill models but few if any are equipped with the ability to model air dispersion and forecast hazardous conditions as discussed in this paper.

Numerical Simulation of Bohai Oil Spill in the Winter Sea Ice Period

The Bohai Sea is a seasonal icy sea area that has the lowest latitude of any sea experiencing icing in the northern hemisphere, and simulation studies on oil spills during its sea ice period are the key to analyzing winter oil spill accidents. This study applied the three-dimensional free surface to establish a high-resolution hydrodynamic model and simulate tidal distributions in the Bohai Sea. Then, the oil spill model of the open sea area and thermodynamic model were combined to establish a numerical model for the Bohai oil spill during the winter sea ice period. The hydrodynamic model and sea ice growth and melting model were verified, and the parameters were adjusted based on the measured values, which indicate that the numerical model established in this paper is of high accuracy,stability and ubiquity. Finally, after checking the calculations repeatedly, the diffusion coefficient for the Bohai Sea was determined to be 1.0×10^(–7 )m^2/s. It is better that the comprehensive weathering attenuation coefficient is lower than that of a non-winter oil spill, with 1.3×10^(–7 )m^2/s being the most appropriate coefficient. This study can provide the reliable technical support for the operational safety and reduction in losses caused by winter oil spill accidents for the petroleum industry.

Effect of localized oil spills on Atlantic loggerhead population dynamics

The purpose of this study is to analyze the population dynamics of loggerhead sea turtles (Caretta caretta) affected by localized oil spills. Methods include development of a spatial, stage-classified matrix model parameterized for the following primary loggerhead populations: Gulf of Mexico, western North Atlantic Ocean, and Florida peninsula. Oil spills are simulated deterministically in each population's nesting region, with 1) oil-induced mortality ranging from 25% to 100% and 2) stage classes affected either proportionally or equally. A transient sensitivity analysis was performed to determine the parameters most influential to the population growth rate. Results suggest that increased protection and understanding of young sea turtles found in the Sargasso Sea is essential to the survival of the species. In addition, findings provide insights into the population dynamics of the At- lantic loggerhead turtles and identify conservation measures appropriate in each oil spill case.

Estimating the Variance of the Proportion of Contaminated Soil by Petroleum Spills Using Two-Dimensional Systematic Sampling under Different Approaches

In leading petroleum-producing countries like Kuwait, Brazil, Iran, Iraq and Mexico oil spills frequently occur on land, causing serious damage to crop fields. Soil remediation requires constant monitoring of the polluted area. One common monitoring method involves two-dimensional systematic sampling, which can be used to estimate the proportion of the contaminated soil and study the oil spills’ geographic distribution. A well-known issue using this sampling design involves the analytical derivation of variance of the sample mean (proportion), which requires at least two independent samples. To address the problem, this research proposed a variance estimator based on regression and a corrected estimator using the autocorrelation Geary Index under the model-assisted approach. The construction of the estimators was assisted by geo-statistical models by simulating an auxiliary variable. Similar populations to those in real oil spills were recreated, and the accuracy of proposed estimators was evaluated by comparing their performance with other well-known estimators. The factors considered in this simulation study were: a) the model for simulating the populations (exponential and wave), b) the mean and the variance of the process, c) the level of autocorrelation among units. Given the statistical and computing burdens (bias, ratio between estimated and real variance, convergence and computer time), under the exponential model, the regression estimator showed the best performance;and for the wave model, the corrected version performed even better.

Modeling the Flow Regime Near the Source in Underwater Gas Releases

Recent progress in calculating gas bubble sizes in a plume, based on phenomenological approaches using the release conditions is a significant improvement to make the gas plume models self-reliant. Such calculations require details of conditions Near the Source of Plume （NSP）; （i.e. the plume/jet velocity and radius near the source）, which inspired the present work. Determining NSP conditions for gas plumes are far more complex than that for oil plumes due to the substantial density difference between gas and water. To calculate NSP conditions, modeling the early stage of the plume is important. A novel method of modeling the early stage of an underwater gas release is presented here. Major impact of the present work is to define the correct NSP conditions for underwater gas releases, which is not possible with available methods as those techniques are not based on the physics of flow region near the source of the plume/jet. We introduce super Gaussian profiles to model the density and velocity variations of the early stages of plume, coupled with the laws of fluid mechanics to define profile parameters. This new approach, models the velocity profile variation from near uniform, across the section at the release point to Gaussian some distance away. The comparisons show that experimental data agrees well with the computations.

Laboratory investigation into the oil diffusion from submarine pipeline under water flow

A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow.The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The oil trajectory, velocity and the rising time to the surface are obtained through this system. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled discharge is the primary factor affecting the rising time of the oil particles. In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity. The study can provide a theoretical reference for the prediction system of oil spill emergency.

Modelling of Potential Pipeline Impact Radius and High Consequence Area in a Wetland Sub-Region of Nigeria

Crude oil transportation through pipelines presents danger to communities along its path. In the Niger Delta region of Nigeria for instance, pipeline vandalism occurs indiscriminately and regularly, such that every segment of a pipeline network becomes a potential target and possibly source of oil spill hazard. In terms of pipeline hazard and risk distribution, the oil plume’s ability to migrate freely in wetlands and encroachment on pipeline right of ways by people increases chances of wider contact and exposure opportunities to inhabitants and the environment. Despite several efforts to mitigate pipeline hazards in the oil and gas sector, none has been effective in Nigeria partly due to paucity of data in public domain and poor public participation. Therefore considering the environmental and human health challenges associated with oil spills, an alternative method was developed using multi-criteria decision analysis to model 1) pipeline hazard zones, 2) potential pipeline impact radius, and 3) high consequence areas with four attribute layers, i.e. land cover, population, river and pipeline to encourage public participation. The model identified land use areas, communities and rivers likely to be susceptible to pipeline hazards and areas requiring regular monitoring and possible intervention. Meanwhile the model sensitivity test indicated that the river layer was most sensitive, while transferability was limited to similar criteria variables. The model can stimulate public participation in pipeline hazard management while policy makers and regulators would find it relevant in oil spill impact mitigation.

渤海湾海上瞬时溢油三维模拟

为实时模拟及预测渤海湾三维海上溢油的动态特征,采用Mike 21 Flow模型计算渤海水动力潮汐,针对瞬时溢油的扩散和漂移过程,建立海上溢油运动数学模型;采用泊松盘采样算法创建不同直径的油粒子,通过Marching Cube算法重建等值面,模拟实现海上溢油过程,并与真实案例的数据对比。溢油模拟结果表明:所建潮汐流数值模型评估溢油事故船舶位置的海面高程、海流速度和海流方向与观测站数据接近;海上溢油运动数学模型原油运动轨迹与与实际轨迹相似;相较于传统溢油模拟可视化工作局限于二维非交互效果,新方法从三维层面提高溢油模型的物理真实感,为海上搜救模拟器生成溢油事故的三维场景、降低人力和财物成本、为海上溢油应急预案的制定提供直观的信息和依据。

基于EFDC模型的靖江河道多码头开发段溢油事故综合污染风险分析

基于环境流体动力学模型EFDC模拟了长江靖江开发段6个码头溢油事故下油膜漂移路径,提出了溢油污染风险评估方法,计算了多码头溢油事故的污染风险指数分布及其对保护区的综合污染风险指数。结果表明:码头位置和周围流场影响油膜的漂移路径;急流区溢油事故产生的油膜峰值迁移速度快,影响距离长,而缓流区溢油事故产生的油膜聚集程度高,影响时间长;多码头溢油事故产生的污染风险主要分布在各油膜路径的叠加区域,在开发段中部至下游末端形成强等级污染风险带,综合污染风险指数约为1.6;风险带主要影响W1保护区,应在高风险区域提前采取应急防范措施。

船舶溢油污染海冰可见光-近红外反射光谱特征及其角度效应

随着北极航线的开通,往来极地冰区的船只数量逐年增加,这使得发生冰区溢油的风险随之增加。冰区溢油具有清理难度大、污染持续时间长等特点,快速准确的监测手段成为提高清理效率、降低污染危害的重要途径之一。遥感技术在开阔水域溢油的监测中得到了广泛应用,但在有冰海区溢油的监测研究较少。尤其对于受溢油污染的海冰的反射光谱特征及其随角度变化规律的研究鲜有报道。通过开展海冰溢油模拟实验,测量不同观测天顶角和相对方位角下油污染海冰的可见光-近红外反射光谱,天顶角每间隔10°采集一次,范围为:-50°~50°,相对方位角包括了:0°、90°、180°、270°。利用光谱标准偏差分析海冰受污染前后的光谱差异,选取差异值最大的波段560 nm作为油污染海冰识别的特征波段。为探寻特征波段反射差异随观测几何变化的规律,构建了一种考虑海冰前向散射特征的核驱动模型Ross Thick-Roujean-r-RPV,并利用实测数据进行检验,在主平面和垂直主平面的拟合误差分别为0.00462、0.00416,拟合效果优于Ross Thick-Li sparse、Ross Thick-Li sparse R、Ross Thick(QU)-Roujean及Ross Thick(QU)-Li sparse R-r-RPV等常用核驱动模型。利用该模型,进一步模拟了不同观测几何条件下油污染前后海冰特征波段反射差异的角度效应。结果表明,海冰在相同观测几何条件下,受污染前后反射光谱存在差异,污染海冰反射率要低于清洁海冰,且清洁海冰在波段1013~1196 nm范围内存在一个波峰,而在受污染后此波峰消失;当观测方位角不同时,海冰反射率也存在差异,具体表现为,在前向方向随着观测角度的增大而增加,而在后向方向则表现为随观测角度的增加而降低;在主平面方向,反射率随观测角度增加则是先增加后降低。在天顶角为50°,相对方位角范围在250°~290°时,光谱差异最大,即最有利于海冰溢油的提取。研究结果能够为冰区船舶溢油监测传感器的波段和观测几何优选提供参考。