薄油层时移地震差异波形特征探讨

开发导致的时移地震差异代表了油藏的岩石物理性质变化,本文从差异波形角度出发,明确了声波阻抗界面的反射系数与油层声波阻抗变化之间的函数关系,进而分析薄油层时移地震差异波形特征.通过分析得出,开发前后油层阻抗变化越大,时移地震的差异振幅幅度越大;薄油层的差异波形特征仅与油层的声波阻抗变化有关,油层声波阻抗增大导致与地震子波微分形式相同的差异波形,油层声波阻抗减小产生的差异波形与180°相位的地震子波微分形式相同;油层声波阻抗变化方向导致差异波形振幅幅度变化的快慢.     

Review of behaviour of oil in freezing environments

The current knowledge of the physical fate and behaviour of crude oil and petroleum products spilled in Arctic situations is reviewed. The fate and final deposition of oil in marine conditions is presented as based on the extant literature.

Spreading models were evaluated for oil on ice, under ice, in snow, in brash ice, and between blocks of ice. Models of oil transport under sheet and broken ice were considered, both for sea and river conditions. The ability of ice sheets to trap oil is discussed in relation to oil storage capacity. The effects of oil on a growing ice sheet were examined, both in terms of ice formation and the thermal effects of oil inclusions in ice. The migration of oil through ice was reviewed, focussing primarily on the movement through brine channels. The effects of oil on the surface of ice were considered, with emphasis on the effects of surface pools on ice melt. Similar consideration was given to the effects of oil on snow on the surface of ice.

The few quantitative studies of oil in open and dynamic ice conditions are reviewed. Observations of intentional small-scale spills in leads and ice fields are reviewed and compared with observations from real spills. The conditions under which “oil pumping” from leads occurs were quantified. The most common ultimate fate of oil in an ice field is to be released onto the water surface.     

Study of genetic evolution of oil inclusion and density of surface oil by measurement of fluorescence lifetime of crude oil and oil inclusion

By using fluorescence lifetime image microscope (FLIM) and time-correlated single photon counting (TCSPC) technique, we measured fluorescence lifetime of crude oils with density of 0.9521–0.7606 g/cm³ and multiple petroleum inclusions from Tazhong uplift of Tarim Basin. As indicated by the test results, crude oil density is closely correlated with average fluorescence lifetime following the regression equation Y=–0.0319X+0.9411, which can thus be used to calculate density of oil inclusions in relation to fluorescence lifetime and density of corresponding surface crude. For type A oil inclusions showing brown-yellow fluorescence from Tazhong 1 well in Tarim Basin, their average fluorescence lifetime was found to be 2.144–2.765 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.852–0.873 g/cm³, indicating that they are matured oil inclusions trapped at earlier stage of oil formation. For type B oil inclusions with light yellow-white fluorescence, their average fluorescence lifetime was found to be 4.029–4.919 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.784–0.812 g/cm³, indicating that they are higher matured oil inclusions trapped at the second stage of oil formation. For type C oil inclusions showing light blue-green fluorescence, their average fluorescence lifetime was found to be 5.063–6.168 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.743–0.779 g/cm³, indicating that they are highly-matured light oil inclusions trapped at the third stage of oil formation.     

Limitations of Monitoring Wells for the Detection and Quantification of Petroleum Products in Soils and Aquifers

Theoretical analysis and laboratory column experiments were carried out to investigate the conditions required for petroleum products (oil) to flow into a well installed through a sandy porous medium contaminated with the oil. The results indicated that oil would flow into a well only after a layer of "free oil" is formed in the adjacent porous medium. Because significant quantities of oil could be stored in the porous medium under the influence of capillary suction prior to the formation of the zone of free oil, the presence of oil in a well would indicate an advanced stage of oil contamination of the subsurface. While monitoring wells could be used to delineate the extent of the free-oil plume and the plume of dissolved petroleum constituents, they are not useful for delineating the extent of capillary held oil.
The experimental results also indicated that the ratio of the oil-layer thickness in the well to that in the porous medium is not a constant as is sometimes assumed in practice. Further, estimates of the oil thickness in the medium based on the oil thickness in wells and on capillary properties measured in the laboratory were sensitive to the values of the parameters used in these estimates. The measured thickness of the oil layer in a monitoring well alone may not yield reliable estimates of the amount of oil in the subsurface, and assuming that the oil-thickness ratio is a constant can lead to inadequate site assessments and inappropriate remedial plans.     

Method for generating parameterized ecotoxicity data of dispersed oil for use in environmental modelling

The aim of the work was to establish methodology for realistic laboratory-based test exposures of organisms to oil dispersions, specifically designed to generate parameterized toxicity data. Such data are needed to improve the value of numerical models used to predict fate and effects of oil spills and different oil spill responses. A method for continuous and predictable in-line production of oil dispersions with defined size distribution of different oil qualities was successfully established. The system enables simultaneous comparison between the effects of different concentrations of dispersion and their corresponding equilibrium water soluble fractions. Thus, net effects of the oil droplet fraction may be estimated. The method provides data for comparing the toxicity of oil dispersions generated both mechanically and with the use of chemical dispersions, incorporating the toxicity of both dissolved oil and droplets of oil.     

Minimal incorporation of Deepwater Horizon oil by estuarine filter feeders

Natural abundance carbon isotope analyses are sensitive tracers for fates and use of oil in aquatic environments. Use of oil carbon in estuarine food webs should lead to isotope values approaching those of oil itself, −27‰ for stable carbon isotopes reflecting oil origins and −1000‰ for carbon-14 reflecting oil age. To test for transfer of oil from the 2010 Deepwater Horizon spill into estuarine food webs, filter-feeding barnacles (Balanus sp.) and marsh mussels (Geukensia demissa) were collected from Louisiana estuaries near the site of the oil spill. Carbon-14 analyses of these animals from open waters and oiled marshes showed that oil use was <1% and near detection limits estimated at 0.3% oil incorporation. Respiration studies showed no evidence for enhanced microbial activity in bay waters. Results are consistent with low dietary impacts of oil for filter feeders and little overall impact on respiration in the productive Louisiana estuarine systems.     

石油双机(有机+无机)混合成因的研究与探索

石油与天然气的成因问题关系到我国乃至世界各国能源结构的配置及其能源在社会与经济发展中的地位和导向.自从17世纪展开对石油的有机与无机成因的争论以来,至今已有约300~400年的历史.尽管有机成因论占据了统治地位,但是无机成因论亦不断地在兴起!通过对这二者的理解和研究,从理论上讲他们都具有一定的物质基础和论据.基于对国内、外一些特异油田的生储环境,原油中所富含的微量金属元素的聚集与散失,某些油田中并未找到卟啉分子这样的生物标志物,碳、氢、氧化学合成实验等方面取得了一定的成效,故全盘否定无机生油的论点和论据确尚感为时过早或欠妥!显然,在以有机物成油为主体的前提下,无机物亦可生成部分石油,并通过运移、渗透到各油田的储集层中应是完全可能的.基于这样的分析、研究和探索,现提出石油的双机(a有机+b无机)混合成因的新理念.诚希能在今后的石油工业发展中,从理论、技术、实验和实践中强化对双机混合成因新理念的深化研究与探索,以达深切理解和扩展石油生、储空间环境等是不无裨益的!     

Comparison of Oil Transmissivity Methods Using Bail‐Down Test Data

This paper evaluates the results from three methods commonly used to estimate oil transmissivity: the modified Cooper solution (Beckett and Lyverse 2002), the modified Bouwer and Rice method (Kirkman 2013), and the modified Jacob and Lohman method (Huntley 2000). Determining the validity of oil transmissivity values is important (e.g., when used in extraction system design and operation) and not straightforward as these methods are based on different assumptions and boundary conditions and introduce different simplifying assumptions to allow for estimating oil drawdown. Data from 289 bail‐down tests performed during an oil remediation project were used in this evaluation. Analysis of these tests produced realistic transmissivity values and good correlation between these three methods, giving the authors confidence in the oil transmissivity values as this correlation is reflected across a significant number of data sets. Secondly, the nature of oil and water recharge to the wells interpreted from Kirkman's J‐ratio values largely validates the Huntley (2000) simplifying assumption that the potentiometric surface will be relatively constant during the test, allowing the use of the modified Bouwer and Rice method. Finally, the impact of oil extraction on measured oil thickness and estimated oil transmissivity was also assessed. The study showed a clear general decrease in both measured oil thicknesses and estimated oil transmissivity during the oil recovery project. However, measured oil thickness and estimated oil transmissivity are not clearly correlated, and, as a consequence, the range of decrease in one parameter does not allow any prediction of the range of decrease in the second parameter.     

Declines in oil-rates of stranded birds in the North Sea highlight spatial patterns in reductions of chronic oil pollution

Strandings of oiled seabirds are used to signal the problem of chronic oil pollution. Species-specific oil rates reflect the risk for marine birds to become oiled at sea. High oil rates were characteristic for seabirds common in areas with frequent oil spills; low oil rates for birds wintering away from the busiest shipping lanes. Declining trends in oil-rates were found, reflecting a reduction in the amount of oil intentionally discharged over the past 50 years. Spatial patterns in the risk to become oiled could be identified, when the winter distribution patterns of the affected birds were incorporated in the analysis. Declines in oil rates were most pronounced in coastal birds. These trends were consistent with tendencies to police nearshore waters more effectively than offshore waters. While levels of chronic oil pollution are much reduced, future emphasis should be to reduce chronic oiling more effectively in offshore waters.     

Consequences of linseed oil spills in salt marsh sediments

In a simulated spill in a salt marsh, linseed oil penetrated rapidly into the sediments at a rate of 10(-7) cm2 s(-1). The oil concentration remained unchanged for the first month after the spill, but 60% of the oil disappeared from the top 30 cm after a further month. The oil adsorbed to and accumulated in the muddy sediments (top 15 cm) leading to decreased sediment permeability, pH, Eh, abundance of plant roots and infauna and to the establishment of anoxic conditions. These changes accompanied transformations in the original fatty acid composition of the linseed oil, mainly associated with a decrease in 18 : 3omega3, an increase in the other fatty acids and the presence of 'new' fatty acids. A rapid increase in the abundance of heterotrophic aerobic and anaerobic bacteria and aerobic oil degrading bacteria, suggested that these micro-organisms degraded the oil. The role of the bacteria in oil degradation was confirmed in laboratory experiments where the fatty acids composition of the linseed oil underwent identical transformations to those obtained in the field. The degradation of linseed oil appears to be a sequential process initiated by aerobic and/or anaerobic bacteria and continued by sulphate reducing bacteria, which were unable to degrade the raw oil.     

波形差异反演方法及其在气藏描述中的应用

在油气藏开发中后期,如何利用的已有的勘探成果和丰富的油气藏知识,加深对勘探区域油气开发潜力的认识,为油气田的稳产高产服务,是摆在油气田中后期开发人员面前的难题.油气田开发的研究人员,利用现有的资料,开发出了很多方法,结合地震测井等资料为油气田的稳产高产做出了巨大的贡献.本文在分析了地震波在地质体中传播过程中能量变化,相应的产生了振幅变化的理论,利用三维地震数据,通过对三维地震数据解释层位对应的波形差异的分析,结合工区内的生产井和开发井的对应地层中的油气信息,进行反演得到地层的波形差异数据体,利用相应的绘图软件绘制二维平面图形,结合工区内的沉积相等地质信息对其数据体进行油藏解释,最终得到波形差异反演数据体,利用波形差异反演数据体进行油气藏的识别、描述和预测,为油气田的中后期开发服务.     

Effects of dispersed oil on mangroves synthesis of a seven-year study

The results of a long-term program to determine the effects of oil and dispersant on red mangroves and black mangroves are presented. Laboratory experiments were conducted to determine the effects of three oils and dispersant on juvenile red mangroves and black mangroves. A field experiment was conducted to determine the effects of a crude oil and dispersant on a mature mangrove forest in Panama. Our studies indicate that exposure of mangrove seedlings to oil and dispersant in the laboratory resulted in changes of growth, respiration, and transpiration, and led to uptake of petroleum hydrocarbons. Exposure of a mature red mangrove forest to oil and dispersant resulted in many of the same effects observed in the laboratory and at other oil spill sites. These effects were greatly reduced at the site treated with oil and dispersant when compared to the site treated with whole oil.     

Superoleophillic electrospun polystrene/exofoliated graphite fibre for selective removal of crude oil from water

During oil spills, the aquatic environment is greatly endangered because oil floats on water making the penetration of sunlight difficult therefore primary productivity is compromised, birds and aquatic organisms are totally eliminated within a short period. It is therefore essential to remove the oil from the water bodies after the spillage. This work reports on the fabrication of oil loving electrospun polystyrene-exofoliated graphite fibre with hydrophobic and oleophillic surface properties. The fibre was applied for the selective adsorption of crude oil from simulated crude oil spillage on water. The maximum oil adsorption capacity of the EPS/EG was 1.15 kg/g in 20 min while the lowest oil adsorption capacity was 0.81 kg/g in 10 min. Cheap oil adsorbent was developed with superoleophillic and superhydrophobic properties.     

Development of airborne oil thickness measurements

A laboratory sensor has now been developed to measure the absolute thickness of oil on water slicks. This prototype oil slick thickness measurement system is known as the laser-ultrasonic remote sensing of oil thickness (LURSOT) sensor. This laser opto-acoustic sensor is the initial step in the ultimate goal of providing an airborne sensor with the ability to remotely measure oil-on-water slick thickness. The LURSOT sensor employs three lasers to produce and measure the time-of-flight of ultrasonic waves in oil and hence provide a direct measurement of oil slick thickness. The successful application of this technology to the measurement of oil slick thickness will benefit the scientific community as a whole by providing information about the dynamics of oil slick spreading and the spill responder by providing a measurement of the effectiveness of spill countermeasures such as dispersant application and in situ burning.

This paper will provide a review of early developments and discuss the current state-of-the-art in the field of oil slick thickness measurement.     

Oil droplet interaction with suspended sediment in the seawater column: Influence of physical parameters and chemical dispersants

The interaction of dispersed oil droplets with large diameter suspended particulate materials (SPM) has been little studied. In the current study, particle size, oil characteristics and chemical dispersant significantly influence the adsorption of oil droplets to SPM in seawater. Sediments with a smaller particulate size (clay) approaching that of the oil droplets (2–20 μm) adsorbed more oil per gram than sediments with large particle size (sand). Heavier, more polar oils with a high asphaltene content adsorbed more efficiently to SPM than lighter, less polar oils. A decrease in the smaller, more water soluble oil components in the sediment adsorbed oil was observed for all oil types. Addition of chemical dispersant decreased the adsorption of oil droplets to suspended carbonate sand in an exponential-like manner. No change in the relative distribution of compounds adsorbed to the sediment was observed, indicating dispersants do not alter the dissolution of compounds from oil droplets.     

Effectiveness and toxicity of an oil dispersant in large outdoor salt water tanks

Use of the dispersant, Oilsperse 43, increased the dispersion of Venezuelan Guanipa crude oil. The resulting mixture was more homogeneous and the oil slick less viscous than in the oil tank. The dispersant appeared to retard formation of the familiar “crust” on the surface. A weathered crude oil plus dispersant mixture with an oil concentration of 250 μg/l was lethal to over 50% of the test organisms, green sea urchins, within 4 days. No mortalities occurred among urchins exposed to the crude oil treatment.     

Biodegradation of petroleum hydrocarbons at low temperature in the presence of the dispersant Corexit 9500

Our study examined the effects of Corexit 9500 and sediment on microbial mineralization of specific aliphatic and aromatic hydrocarbons found in crude oil. We also measured gross mineralization of crude oil, dispersed crude oil and dispersant by a marine microbial consortium in the absence of sediment. When provided as carbon sources, our consortium mineralized Corexit 9500 the most rapidly, followed by fresh oil, and finally weathered oil or dispersed oil. However, mineralization in short term assays favored particular components of crude oil (2-methyl-naphthalene > dodecane > phenanthrene > hexadecane > pyrene) and was not affected by addition of nutrients or sediment (high sand, low organic carbon). Adding dispersant inhibited hexadecane and phenanthrene mineralization but did not affect dodecane and 2-methyl-naphthalene mineralization. Thus, the effect of dispersant on biodegradation of a specific hydrocarbon was not predictable by class. The results were consistent for both high and low oiling experiments and for both fresh and weathered oil. Overall, our results indicate that environmental use of Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through selective microbial mineralization of hydrocarbons.     

Innovative Techniques for Measuring the Oil Content of Oil-Contaminated Porous Media

The oil content of oil-contaminated porous media is an important parameter for the assessment and remediation of oil pollution in soil and groundwater. However, an accurate measurement method is not available. In this study, we propose a new equation to calculate the oil content of water-bearing media based on traditional extraction–ultraviolet spectroscopy. Further, an improved experimental method was developed. The results indicate that the pure solid weight and oil content of oil-contaminated media can be accurately determined by introducing the oil drying loss coefficient (γ). The average relative errors of the improved method range from −0.14% to −0.96%. They are much smaller than errors of −4.49% to −10.97% of the original methods, indicating that the accuracy of measured oil content is enhanced. In addition, the accuracy of the new method does not depend on oil volatility and oil content.     

Structure of residual oil as a function of wettability using pore-network modelling

In the water flooding of mixed-wet porous media, oil may drain down to relatively low residual oil saturations (S_or). Various studies have indicated that such low saturations can only be reached when oil layers in pore corners are included in the pore-scale modelling. These processes within a macroscopic porous medium can be modelled at the pore-scale by incorporating the fundamental physics of capillary dominated displacement within idealised pore network models. Recently, the authors have developed thermodynamic criteria for oil layer existence in pores with non-uniform wettability which takes as input geometrically and topologically representative networks, to calculate realistic S_or values for mixed-wet and oil-wet sandstones [16, 21]. This previous work is developed in this paper to include (i) the visualisation of the 3D structure of this residual oil, and (ii) a statistical analysis of this “residual/remaining” oil. Both the visualisation and the statistical analysis are done under a wide range of wettability conditions, which is reported for the first time in this paper.The structure of residual oil for strongly water wet systems is well known (where residual = remaining oil) and our model agrees with this but this structure changes radically for mixed wet systems (where residual ≠ remaining) and this has not yet been visualised experimentally. We find that for more water-wet systems high final residual oil saturations are reached at relatively small amounts of water injected and this oil is present in the pores as bulk oil. On the other hand, for more oil-wet systems we find a slow decrease of the amount of remaining oil with increasing amounts of injected water. During the process, the remaining connectivity of the oil phase is increasingly provided by oil layers only, hence the slow drainage. The final residual oil saturation, only reached in the theoretical limit of an infinite amount of injected water, is almost entirely contained in large number of (relatively low volume) oil layers, which are present in pores of most radius sizes.     

The bacterial community composition of an active oil field in the northwestern Gulf of Mexico

The bacterial composition of the water column around two oil production platforms and a control site was examined. Samples were collected during three seasons of a 12-month sampling period three water depths were sampled at all stations occupied.No major differences were discovered in taxonomic or physiological makeup of bacterial populations of the oil field and control site. The genus Pseudomonas predominated at the oil field stations and the control. Bacterial numbers were lower for oil field stations than the control and generally decreased with depth. Microbial biomass estimates were consistently higher at the control site. Oil degrading and sulphur oxidizing bacteria were more numerous within the oil field, and their numbers decreased with distance from the platforms. Buccaneer crude oil did not adversely affect growth or attachment ability of oil field isolates.