Effects of sampling effort on the estimation of spatial gradients in a tropical reservoir impacted by an oil refinery

We investigated the effects of increase in sampling effort (30-1043 sampling points) on the accuracy of assessment of the spatial patterns of surface-water quality in a eutrophic tropical reservoir. The investigation was carried out during the dry season, when previous investigations showed that the spatial heterogeneity is more stable. A multi-parameter Yellow Springs Instruments probe coupled to a TechGeo D-GPS was used. This system is equipped to measure and store in a continuous recording mode, several physical and chemical parameters linked to geographical coordinates obtained with a precision of less than 1 m. We used different geostatistical approaches to determine the optimal number of sampling points required to reflect the real spatial patterns of water quality in the system. This approach was tested in a small tropical reservoir (Ibirité) that receives effluents from an oil refinery (the state-owned REGAP oil refinery, PETROBRAS) located near the city of Belo Horizonte. The study showed not only that the spatial patterns of water quality are significantly affected by sampling effort but also it was demonstrated that the establishment of an adequate sampling program is a critical point for the precise identification of source points of pollution. The results of this investigation enabled us to demonstrate the potential uses and limits of this method for rapid assessment of the water quality of lakes and reservoirs that receive external inputs of water contaminants or nutrients.     

Oil refinery wastewater treatment using coupled electrocoagulation and fixed film biological processes

Oil refinery wastewater was treated using a coupled treatment process including electrocoagulation (EC) and a fixed film aerobic bioreactor. Different variables were tested to identify the best conditions using this procedure. After EC, the effluent was treated in an aerobic biofilter. EC was capable to remove over 88% of the overall chemical oxygen demand (COD) in the wastewater under the best working conditions (6.5 V, 0.1 M NaCl, 4 electrodes without initial pH adjustment) with total petroleum hydrocarbon (TPH) removal slightly higher than 80%. Aluminum release from the electrodes to the wastewater was found an important factor for the EC efficiency and closely related with several operational factors. Application of EC allowed to increase the biodegradability of the sample from 0.015, rated as non-biodegradable, up to 0.5 widely considered as biodegradable. The effluent was further treated using an aerobic biofilter inoculated with a bacterial consortium including gram positive and gram negative strains and tested for COD and TPH removal from the EC treated effluent during 30 days. Cell count showed the typical bacteria growth starting at day three and increasing up to a maximum after eight days. After day eight, cell growth showed a plateau which agreed with the highest decrease on contaminant concentration. Final TPHs concentration was found about 600 mgL⁻¹ after 30 days whereas COD concentration after biological treatment was as low as 933 mgL⁻¹. The coupled EC-aerobic biofilter was capable to remove up to 98% of the total TPH amount and over 95% of the COD load in the oil refinery wastewater.     

松辽盆地双城—太平川地区原油地球化学特征及其成熟度差异

松辽盆地北部双城—太平川地区扶杨油层原油地球化学特征相近,正构烷烃分布完整,呈单峰型,主峰碳主要为C23,部分原油具有轻碳优势,奇偶优势不明显。三环萜烷含量较丰富,部分原油伽马蜡烷、孕甾烷和升孕甾烷含量较高,规则甾烷呈"V"型分布,碳同位素值偏轻,生源构成以低等水生生物和菌藻类为主,兼有高等植物生源输入,母源形成环境为微咸水还原—淡水氧化环境。本区原油的总体特征比较接近,具有相似的生源母质和有机相,但其成熟度存在着一定差异。根据生物标志物参数,原油分为三个组群,即低成熟油、低成熟—中等成熟油和中等成熟油,主要为低成熟—中等成熟原油。认为研究区具有形成低成熟油的有利烃源条件,应该加强对低成熟油的勘探开发。同时加强长春岭背斜带及其周缘构造高部位有利圈闭的勘探与评价。     

塔里木巴什托油气田巴楚组顶部油气层录井特征分析

详细分析了巴什托油气田BK2、BK3H、BK4H以及BK5H等6口井的地质录井资料,显示巴楚组顶部油气层自上而下见到的含油气级别一般为油斑、油迹、气测异常等,上好下差,油气主要集中于顶部油气层之顶上,反映出油气向上运移储集比较好。巴楚组及以上地层纵、横向上的稳定性较好,深度、厚度均变化不大,且以M4井为中心向各方向均呈现增厚—减薄有规律的交替变化。巴什托油气田巴楚组油藏具有较好的开采价值,但还应不断钻探寻找新的含油气构造,发现新的油气田。     

国内外生物礁油气勘探现状与我国南海生物礁油气勘探前景

世界生物礁油气资源非常丰富,随着生物礁油气勘探开发的不断深入,生物礁油气探明储量和产量不断增加,所占比重越来越大。南海是我国最大的边缘海,其特殊的构造背景、多种类型礁的发育和良好的生储盖组合等都决定了南海生物礁油气勘探的广阔前景。建议加快南海勘探开发的步伐,充分利用南海丰富的油气资源。     

Integrated assessment for establishing an oil environmental vulnerability map: Case study for the Santos Basin region,Brazil

The growth of maritime transport and oil exploitation activities may increase the risk of oil spills. Thus, plans and actions to prevent or mitigate impacts are needed to minimize the effects caused by oil. However, tools used worldwide to support contingency plans have not been integrated, thus leading to failure in establishing priority areas. This investigation aimed to develop indices of environmental vulnerability to oil (IEVO), by combining information about environmental sensibility to oil and results of numerical modeling of spilled oil. To achieve that, a case study concerning to oil spills scenarios in a subtropical coastal area was designed, and IEVOs were calculated and presented in maps, in order to make the information about the areas’ vulnerability more easily visualized. For summer, the extension of coastline potentially affected by oil was approximately 150 km, and most of the coastline presented medium to high vulnerability. For winter, 230 km coastline would be affected, from which 75% were classified as medium to high vulnerability. Thus, IEVO maps allowed a rapid and clearer interpretation of the vulnerability of the mapped region, facilitating the planning process and the actions in response to an oil spill.     

Wave-induced drift of large floating sheets

In this article we study the wave-induced drift of large, flexible shallow floating objects, referred to as sheets. When surface waves propagate through a sheet, they provide a mean stress on the sheet, resulting in a mean drift. In response, the sheet generates an Ekman current. The drift velocity of the sheet is determined by (i) the wave-induced stress, (ii) the viscous stress due to the Ekman current, and (iii) the Coriolis force. The sheet velocity and the current beneath the sheet are determined for constant and depth-varying eddy viscosities.     

Ecological Risk Assessment of Benzo[a]pyrene in Yellow River Delta

Ecological risk assessment is of great significance to promoting the rational management effectively for the oil‐polluted areas. A comprehensive evaluation method of ecological risk, including probabilistic risk assessment and regional ecological risk assessment, is developed through employing the contaminant benzo[a]pyrene as an indicator to assess ecological risk of five oil mining plots, respectively in Yellow River Delta. In this study, firstly we evaluate the ecological risk probability of five oil mining plots using overlapping area of probabilistic curves, and the results show that local ecological risk varies between the maximum 0.4 and the minimum 0.01. Then we overlay boundaries of five administrative divisions in Yellow River Delta and the spatial distribution patterns of ecosystems to generate new risk receptor plaques, and calculate the integrated value of 30 specifically classified plaques for comprehensive evaluation of ecological risk. The results, fluctuating within the range of 0.00005 and 0.25, indicate that local government should be vigilant to ecological risk of benzo[a]pyrene to some extent, although the current situation is not severe in whole.     

油气输导体系研究现状及存在问题的探讨

油气输导体系是油气成藏体系的必要元素,也是油气运移研究的薄弱环节。人们对于这一概念的阐述各不相同,绝大多数学者将其划分为高孔渗砂体、断层及裂缝、不整合面以及它们两两或全部的复合输导体系四种类型,目前对输导体系的研究也集中在这四种类型上。对高孔渗砂体的研究主要集中在孔隙结构、渗透率和优势运移通道上;对断层的研究主要集中在断层泥、非渗透性物质、两盘特征、断层面应力及断层活动性上;对不整合面的研究主要集中在其产状、性质、类型及岩性组合等方面。输导体系的类型划分应当以渗透率非均质性为依据,同时充分考虑烃源岩。从盆地沉积演化的角度出发研究各类输导体系的分布,也是油气运移研究领域中的薄弱环节。     

河南濮城油田沙二上2+3砂层组末端扇沉积特征及剩余油分布

本文以濮城油田沙二上2+3砂层组为例,分析了末端扇储层的沉积特征,建立了末端扇沉积模式,确定了剩余油分布.末端扇储层分为近端亚相、中部亚相和远端亚相,中部亚相的分流河道微相是主要储集砂体.剩余油平面上主要集中在分流河道侧翼过渡区及近水道漫溢、远水道漫溢和分散的井网难控制的小透境体中,垂向上集中在正韵律顶部和反韵律底部等物性差的地方.二砂组主要富集在S23、S24小层的近气顶区,三砂组主要富集在S34、S35小层的濮53、文17断块构造高部位及注采不完善的地区.