Detecting surface oil slick related to gas hydrate/petroleum on the ocean bed of South China Sea by ENVI/ASAR radar data

For exploring the distribution of oil slick related to gas hydrate or petroleum in the northern part of South China Sea and evaluating the potential of ENVI/ASAR radar data for detecting oil slick, this paper tries to detect the oil slick on ocean surface of some potential areas in South China Sea and map oil slick from anomaly area in radar image. Seven surface oil slicks in Qiongdongnan Basin and four potential targets of oil slicks in Taixi–Dongsha Basin were detected and extracted by using ENIV/ASAR data. The anomalies of the radar image representing oil slick are validated by in-site sampling and laboratory analyzing. The Gas Chromatograph (GC) results of the extracted oil from the water samples gathered from the sites of detected oil slick demonstrate a typical composition of oil rather than that of ocean microbial origins, and Total Organic Carbon (TOC) concentrations in two designed vertical profiles keep steady in different depths, showing that the organic contents in water column are steady from the deep area to ocean surface. These results suggest the detected oil slick is a thin floating oil rather than a thick spill. Influencing factors to the results of oil slick detection including wind speed, current, small islands and capes as well as deep-sea petroleum reservoirs are discussed. The results in this study exhibit that extracting the anomaly signals related to oil slick related to oil/gas seeps using image processing techniques from ENVI/ASAR data is helpful to predict anomaly areas as potential targets for further exploration in this area.     

Simulation of the movement and dispersion of oil slicks in the Arabian Gulf

The extensive oil drilling and transportation activities in the Arabian Gulf increased the possibility of oil spills and the consequent threat of oil pollution to the regional ecology. The available literature concerning the main aspects of the physical oceanographic characteristics affecting the movement and spreading of oil spill in the Gulf are reviewed. It is concluded that evaporation, wind-driven currents, and sandfall are important as weathering processes, while tidal currents cause lateral spreading of the slick. Oil spill modelling has shown some usefulness in estimating the trajectories of few major spills illustrated by reference to three models developed for the Gulf. The performance of these models, their capabilities and limitations are reviewed. Recommendations are made to gather more data on the behavior of oil spills in this particular environment.     

Monitoring large oil slick dynamics with moderate resolution multispectral satellite data

Accidental release of crude oil into the sea due to human activity causes water pollution and heavy damages to natural ecosystems killing birds, fish, mammals and other organisms. A number of monitoring systems are used for tracking the spills and their effects on the marine environment, as well as for collecting data for feeding models. Among them, Earth observation technologies play a crucial role and moderate spatial resolution satellite systems are able to collect images with a very short revisit time or even daily. This paper describes the use of Moderate-Resolution Imaging Spectroradiometer data for monitoring large oil slicks with the fluorescence/emissivity index and object-based image analysis. Two case studies are presented: the Deepwater Horizon (2010) and the Campos Basin (2011) oil spill accidents. Results show that it is possible to track the dynamics of the slick both for massive and long-lasting accidents and for smaller and very quick accidents. The main advantages of the method proposed are a straightforward implementation, a fast and semi-automated data processing and the capability of integration of daytime and nighttime acquisitions, as well as its adaptability to different sensors.     

Numerical modeling of two-phase fluid flow and oil slick transport in estuarine water

Oil spills is one of the most important hazards in the estuarine and coastal water. In recent decades, engineers try to predict the status of oil slick to manage the pollution spreading. The prediction of oil slick transport is carried out mainly by means of numerical models. In the current study, the development and application of a two-phase fluid flow model to simulate oil transport in the marine environment are presented. Different transport and fate processes are included in the developed model. The model consists of the Lagrangian method for the advection process, the Random Walk technique for horizontal diffusion process and the empirical equations for the fate processes. The major forces for driving oil particles are fluid current, wind speed and turbulent flow. Therefore, the multi-component hydrocarbon method has been included to the developed model in order to predict fate processes. As prediction of particle velocity components is of major importance for oil slick advection, therefore the binomial interpolation procedure has been chosen for the particle velocity components computations. In addition, shoreline boundary condition is included in the developed model to simulate shore response to oil slick transport near the beaches. The results of the model applications are compared with the analytical solutions, experimental measurements and other numerical models cited in literature. Comparisons of different sets of results represent the capability of developed model to predict the oil slick transport. In addition, the developed model is tested for two oil spill cases in the Persian Gulf.     

An assessment on oil spill trajectory prediction: Case study on oil spill off Ennore Port

A Liquefied Petroleum Gas (LPG) tanker and a chemical tanker collided two nautical miles off Ennore port on 28 January, 2017. Around 196.4 metric tons (MT) of Heavy Furnace Oil (HFO) was spilled and drifted towards the shore. Oil spill drift advisory and prediction was made by Indian National Centre for Ocean Information Services (INCOIS) using General National Oceanic and Atmospheric Administration (NOAA) Operational Modeling Environment (GNOME), an oil spill trajectory model. The trajectory model was forced with analysed and forecasted ocean currents from Global Ocean Data Assimilation System (GODAS) based on Modular Ocean Model 4p1 (GM4p1). It was found that spread of HFO obtained from oil spill trajectory model GNOME, has matched well with the observed spread from Sentinel-1A satellite dataset. However, the spread of the HFO was underestimated by the trajectory model, when forced with forecasted GM4p1 currents. Additional ground truth observation from Indian Coast Guard also corroborates this finding.     

近海油气藏渗漏烃的检测方法综述

主要总结了海域油气藏渗漏烃的航空遥感和地球化学检测方法.遥感测量可以从宏观上圈定海面油膜的分布范围,是海上油气藏勘探前期常用的廉价方法;海底沉积物取芯测量和海水嗅探器现场分析是海域油气藏渗漏烃地球化学检测的主要手段,海水样品的脱气处理是海水介质中渗漏烃地球化学检测的关键环节;海水和海底沉积物取样设备与脱气技术的不断完善,为海域油气藏渗漏烃的检测提供了基本保障;目前,底层水采样分析与海底沉积物取芯分析已成为一种有效且相对经济的海域油气藏渗漏烃检测技术组合,与一些地球物理方法结合应用,可有效地圈定海底下方渗漏源的位置.     

Sublethal Effects of Crude Oil on the Community Structure of Estuarine Phytoplankton

While the ecological impacts of crude oil exposure have been widely studied, its sublethal effects on phytoplankton community structure in salt marsh estuaries have not been well documented. The purpose of this study was to simulate oil spill conditions using a microcosm design to examine short-term (2 day) changes in phytoplankton community composition and total biomass following exposure to crude oil obtained from the Deepwater Horizon oil spill and a mixture of Texas crude oils. Microcosm experiments were performed in situ in North Inlet Estuary near Georgetown, SC. A control and six replicated experimental treatments of crude oil additions at final concentrations of 10, 50, or 100 μl l⁻¹ of either Deepwater Horizon spill oil or the Texas crude mixture were incubated under in situ conditions. Photopigments were analyzed using high-performance liquid chromatography and community composition was determined using ChemTax. Total phytoplankton biomass (as chl a) declined with increasing crude oil concentrations. Prasinophytes, the most abundant microalga in both experiments, showed no response to oil exposure in one experiment and a significant negative response in the other. Diatoms euglenophytes and chlorophytes appeared relatively resistant to oil contamination at the exposure levels used in this study, maintaining or increasing their relative abundance with increasing oil concentrations. Chlorophytes and cyanobacteria increased in relative abundance while cryptophyte abundance decreased with increasing oil concentrations. The results of these experiments suggest that low levels of crude oil exposure may reduce total biomass and alter phytoplankton community composition with possible cascade effects at higher trophic levels in salt marsh estuaries.     

Application of an oil spill vulnerability index to the shoreline of lower Cook Inlet,Alaska

Offshore tracts in Alaska's lower Cook Inlet are scheduled to be opened for exploratory petroleum drilling in the near future. Because of the potential for oil spills resulting from this activity, a field study of the coastal zone was conducted in June 1976. A total of 1216 km of shoreline was classified into 3 types: erosional (45 percent), neutral (38 percent), and depositional (17 percent). These were further subdivided into 16 subclasses on the basis of small scale morphological features. This classification was used in conjunction with a vulnerability index of potential oil spill damage, developed through study of three major oil spills, to predict the longevity of oil in the different coastal environments of the Inlet. On a scale from 1 to 10, 45 percent of the shoreline has low values of 1 to 4, which means that oil would be dispersed by natural processes within less than six months after a spill on these coasts. Values from 4 to 6 were assigned to 13.4 percent of the shoreline, where oil residence time may be up to one year. A 6 to 10 rating was assigned to 41.5 percent of the shoreline, where oil contamination may remain for periods of two to ten years, or possibly longer should no major clean-up procedures be initiated. We propose that the use of this type of vulnerability indexing, in conjunction with a biological susceptibility index and oil spill trajectory models, would provide a rational basis for decision making concerning the location of on- and off-shore oil facilities and the design of oil spill contingency plans.     

Mathematical simulation on the oil slick spreading and dispersion in nonuniform flow fields

The viscous fluid boundary layer equations were adopted to characterize the velocity distribution across the vertical section of the oil slick on moving water. The velocity profile was found to be the combination of linear and parabolic distribution. A numerical model including spreading and dispersion was developed to describe the oil slick’s early movement in the open and ice-covered water. The flume test was conducted to determine the dispersion coefficients (K_x) and the effects of velocity and wave height on the slick’s dispersion were also investigated. In the open water, K_x increased from 4.34 cm²/s to 20.08 cm²/s as the velocity changed from 3 cm/s to 12 cm/s. Acoefficient β that characterized K_x fluctuated at 1.5 when wave heights were between 20 mm and 70 mm. Under ice, the slick didn’t move until the velocity exceeded 6 cm/s and K_x increased from 2.69 cm²/s to 5.64 cm²/s as the velocity changed from 6 cm/s to 12 cm/s. β remained 0.4 when wave heights were between 20 mm and 60 mm. The model performed very well in predicting the slick’s position and length during the gravitation-inertia phase for the two situations when relevant dispersion coefficients were input.     

Short-Term Effects of an Oil Spill on Marsh-Edge Fishes and Decapod Crustaceans

On 19 April 2005, an oil spill occurred in southeastern Louisiana’s Barataria Bay estuary. We used a drop sampler to characterize the marsh-edge nekton community. Thirty-six locations were sampled in pre- and post-spill time frames from March through May 2005. Before–after control–impact (BACI) analyses of the total number of individuals (fishes + decapod crustaceans), total fishes, and sensitive species found significant interactions between the temporal (before/after) and spatial (control/impact) treatments and indicated an effect of the oil spill. Nonparametric analyses detected varied faunal assemblages across temporal treatments, but were similar in species composition among spatial treatments. While the BACI analyses showed event effects, differences were not strongly detected in nonparametric analyses of community structure. Fish are mobile and left the spill area after the disturbance, whereas the less mobile but more numerous benthic decapod crustaceans remained. The overall community structure appears to be robust and quickly recovered from the localized spill event.     

国产旋转导向及随钻测井系统在渤海某油田的应用

旋转导向和随钻测井系统可在精确、高效控制井眼轨迹和快速识别地层性质的同时大幅度提高作业效率,降低作业成本。尤其在海上油气开发过程中具有较好的提效效果,但是长期以来该领域均被国外石油公司垄断且租赁价格高昂。中海油国产化研制的Welleader旋转导向系统、Drilog随钻测井系统经过多次试验达到了入井应用要求,在渤海某平台调整井钻井作业中进行了应用,结果表明该套系统旋转导向系统轨迹控制满足定向井轨迹要求、测斜数据准确、测井质量符合标准要求,能够实现钻井过程中的轨迹控制和测井要求。     

Research Status and Application Prospect of Shelf-Edge Trajectory Analysis

Trajectory analysis is the hotspot and research frontier of sedimentology and sequence stratigraphy. Compared with conventional analytical methods, trajectory analysis is aiming at identifying sedimentary systems and predicting sandstone reservoirs more directly. The definition of trajectory analysis has been made by Helland-Hansen as “The study of the lateral and vertical migration of geomorphological features and associated sedimentary environments, with emphasis on the paths and directions of migration”. Based on current research progress, the basic concepts and methods of trajectory analysis, types of basinward-migrating trajectories (ascending, flat and descending), quantitative parameters and the application in predicting deep-water sandstone reservoirs were introduced. Trajectory analysis mainly centers on two scales: Shoreline trajectories and shelf-edge trajectories. The formation of basin-floor fans has close relation with shelf-edge trajectories, and multiple case studies have confirmed that large-scale basin floor fan usually form under flat or descending shelf-edge trajectories. As research advances, trajectory analysis theory, which developed in continental margins, is believed to have been influenced by multiple factors. Thus, the accurate prediction of sandstone reservoirs requires the comprehensive consideration of the influence of sediment supply, accommodation spaces, past climate and so on. In addition, the problems and extensions of trajectory analysis were also introduced, including ①the along-strike lateral differential evolution; ② trajectory analysis theory in hydrological-closed sedimentary basins; ③the application of trajectory analysis in carbonate settings. As a developing theory, the terminology of trajectory analysis still needs standardization, and the coupling between shelf-edge trajectories and the development and distribution of deep-water sandstones also needs further understanding. The next research focus could be placed on interpreting the evolution of three-dimensional sedimentary systems, and the extension of shelf-edge trajectory theory to hydrologically-closed basin and carbonate sedimentary environments. The research methods of trajectory analysis should also follow the newest trends to allow researchers to better study the evolution of shelf-edge trajectories, for instance, integrating high-resolution seismic data and logging data, core samples, outcrops and high-resolution dating techniques to describe ancient sedimentary environment and geomorphology, combining satellite imaging, ground penetrating radar to portray the modern morphology of continental margins, and utilizing remote sensing to construct more precise three-dimensional models for outcrops.     

Hydrocarbon-Degrading Bacteria and Paraffin from Polluted Seashores 9 Years after the Nakhodka Oil Spill in the Sea of Japan

Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria （genus Pseudomonas） and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis （0.422, 0.377, and 0.250 nm d-spacing） in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.     

基于数学统计法的海岸带溢油指纹鉴定研究：以大连石油污染事件为例

基于数学统计模式对溢油的指纹进行数字化识别对实现快速、准确进行溢油鉴别具有重要意义。介绍了重复性限法、聚类分析法和t检验法等多元统计分析方法进行溢油鉴别的方法、原理及鉴别原则;并以大连“七一六”输油管道爆炸事故为典型溢油案例,采用重复性限法对溢油鉴别常规诊断比值进行评价和筛选,并利用聚类分析法和t检验法对大连金沙滩和海贝广场附近出现的油污进行了污染源的有效鉴定。     

陆架边缘三角洲研究进展及实例分析

自上世纪90年代以来,发育在大陆架边缘的一种特殊类型的三角洲（shelf-edge delta）,因其厚度大,分布面积广,储层物性好,常常与陆坡深水扇体伴生,成藏条件好等特点而引起了广泛关注,成为当前国际沉积学界研究的热点和油气勘探新领域。陆架边缘三角洲一般形成于相对海平面下降或低位时期,主要受控于物源供给、可容纳空间和气候变化,并受到陆坡构造活动影响;也可发育在高位时期,受到波浪与潮汐的影响。前人提出了利用陆架边缘迁移轨迹预测深水沉积和基于陆架斜坡发育模式预测深水沉积的模型,即强烈抬升的陆架边缘迁移轨迹、强烈加积的陆架斜坡发育模式,对应的深水区物质传输体系为泥质;水平—轻微下降的陆架边缘迁移轨迹、强烈前积的陆架斜坡发育模式,预示着大量砂体被搬运至深水区;轻微抬升的陆架边缘迁移轨迹、加积与前积的陆架斜坡发育模式,暗示深水沉积砂体发育介于上述二者陆架边缘迁移与深水扇预测模式之间。陆架边缘三角洲—深水扇规模砂体毗邻优质烃源岩,具备多种类型的油气运移通道,成藏条件良好,是油气勘探的有利领域。实例分析表明:渐新世珠海组沉积时期构造相对稳定,在古珠江充足的供源条件下,南海北坡珠江口盆地鹤山凹陷发育陆架边缘三角洲并伴随陆架不断向海迁移而不断进积,S型前积体不断向海迁移,并在晚期发育下切谷及大型盆底扇沉积。鹤山凹陷珠海组沉积时期发育水平—轻微下降的陆架边缘迁移轨迹,对应于强烈前积的陆架斜坡发育模式,在珠海组沉积晚期发育较大规模叠合连片深水扇富砂沉积体系,是研究区极好的潜在油气勘探目标。     

The influence of capillarity on multiphase flow within porous media: a new model for interpreting fluid levels in groundwater monitoring wells in dynamic aquifers

A new approach is presented to calculate the volume of oil in the underground at an oil spill site from fluid levels in monitoring wells. The approach includes the effects of hysteresis due to irregular pore geometry and to phase entrapment. It is possible to explain the drastic changes in the oil thickness in a monitoring well due to the decrease and increase in the groundwater table. A correct evaluation of the oil volume infiltrated underground from an oil spill and the effective control of remediation works can only be done by using the newly developed approach with a consideration of the dynamic changes in the groundwater table.     

Multimedia environmental analysis of PCBs fate and transport mechanism through a case study of transformer oil leakage

Transformer oil leakage having large quantity of PCBs is one of the most deplorable incidents resulting in huge negative impacts on the environment. In this paper, two different models, i.e. CHEMCAN and the hydrocarbon spill screening models, were applied to the case study adapted from a real case of PCBs in transformer oil spill in Montreal. The oil migration was examined in three dimensions including site-specific data, soil characteristics and hydrogeological properties. This study aims to investigate the fate, transport and transformation rates of PCB in the soil, the unsaturated and the saturated zones. The proposed modelling concept helps to define the processes to be used in characterization of soil and subsurface environment as a receptor of transformer oil spill. This study includes the simulation techniques for assessing the effect of PCBs on groundwater and soil. Results from multimedia environmental model and HSSM model verify with each other, and both show that 92.7 % of PCBs were found in soil as compared to groundwater. Considering decay and sorption processes at spill location, concentration of PCBs in soil was >50 mg/kg. This study can serve as a basis for further analysis and assist in selection of remediation technique.     

输油管道建设对鄂尔多斯盆地地下水影响预测

探讨输油管道建设对鄂尔多斯盆地地下水环境的影响,根据研究区地质及水文地质特征,结合石油管道事故所设定条件,按照风险最大化原则,采用“瞬时注入示踪剂——平面瞬时点源”模型进行预测分析,结果表明：污染物在地下水中运移的1460d内,最大迁移距离呈先增大后减小的趋势,最大距离为116．05m;中心点浓度则从433．13mg／L减少至〈0．3mg／L,低于《生活饮用水卫生标准（GB5749—2006）》中石油类限值（0．3mg／L）;泄漏中心点逐渐运移至下游49．64m处,对地下水敏感点不会产生明显影响。     

Impact of ‘Chitra’ Oil Spill on Tidal Pool Macrobenthic Communities of a Tropical Rocky Shore (Mumbai,India)

A collision between the ships MSC Chitra and MV Khalijia 3 in the mouth region of Mumbai Harbour led to a leakage of around 800 t of fuel oil in August 2010, affecting the rocky intertidal region of Colaba. To evaluate the impact of this catastrophic event on the resident biota, a 15-month-long sampling programme was initiated in the oil-affected area immediately after the spill. Petroleum hydrocarbons in water and sediment organic carbon values were high just after the oil spill but subsequently decreased in the following months. In total, 70 macrobenthic taxa were identified. Univariate diversity indices indicated that while the ecological status of the site, albeit briefly, was affected during August 2010, a healthy environment prevailed subsequently. Cluster and multi-dimensional scale (MDS) analyses distinctly segregated the oil impacted monsoon months from the other sampling months. BIOENV analyses indicated that petroleum hydrocarbons and organic carbon were the anthropogenic parameters influencing macrobenthic community structure. Benthic Opportunistic Polychaetes Amphipods (BOPA) index was used to evaluate the ecological quality of the study area as the index is sensitive to oil pollution. Low BOPA values throughout the study period indicated that the environment was good with few opportunistic species. Comparison with past data revealed that the oil spill did not have long-term deleterious effects on the macrobenthic species diversity of this rocky beach, and reasons thereof are discussed.     

煤层气水平对接井用单弯无稳螺杆钻具组合造斜能力预测

作为煤层气开发水平对接井定向钻进最为常用的单弯无稳螺杆钻具组合,其造斜能力的预测,直接影响着井眼轨道预测及井眼轨迹控制。采用几何计算的方法,以三点定圆法为理论基础,通过分析考虑结构弯角位置影响和井径扩大影响的单弯双稳螺杆钻具组合造斜率预测的相关算法,结合三弯矩方程组的相关理论,提出单弯无稳螺杆钻具组合造斜率的预测算法,通过现场实践应用验证。该算法可用于沿煤层定向轨迹延伸钻进的井底导向钻具造斜能力预测。