黄骅坳陷孔南地区孔二段湖盆结构恢复

孔南地区孔二段受到沧东断层、徐西断层等活动影响,地层结构遭受强烈的改造,原有湖盆结构发生了很大的变化。隆起区构造单元富泥质沉积,凹陷构造单元富砂质沉积,成为研究区孔二段的主要特征之一,也成为研究的难点。本文通过对研究区孔二段沉积厚度、岩相、沉积相、构造分析以及等时地层格架下的沉积体系展布规律分析等,对孔二段沉积时期湖盆结构进行了恢复,改变了以往认为孔店期为断陷产物的认识,得出孔二段沉积时期,湖盆总体为坳陷盆地,现今处于盆地中心的孔店隆起构造带为孔二期的古湖盆中心和沉降中心。这一结论对认识黄骅坳陷孔南地区盆地演化,成因机制和油气勘探具有重要的意义。     

Estimating recharge rates with analytic element models and parameter estimation

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation.     

Ground water modeling applications using the analytic element method

Though powerful and easy to use, applications of the analytic element method are not as widespread as finite-difference or finite-element models due in part to their relative youth. Although reviews that focus primarily on the mathematical development of the method have appeared in the literature, a systematic review of applications of the method is not available. An overview of the general types of applications of analytic elements in ground water modeling is provided in this paper. While not fully encompassing, the applications described here cover areas where the method has been historically applied (regional, two-dimensional steady-state models, analyses of ground water-surface water interaction, quick analyses and screening models, wellhead protection studies) as well as more recent applications (grid sensitivity analyses, estimating effective conductivity and dispersion in highly heterogeneous systems). The review of applications also illustrates areas where more method development is needed (three-dimensional and transient simulations).     

Nitrogen isotope ratios in estuarine biota collected along a nutrient gradient in Narragansett Bay, Rhode Island, USA

Stable nitrogen isotope ratios were used to study the incorporation of anthropogenically-derived nitrogen into the food webs of salt marsh systems along a contamination gradient in Narragansett Bay. Nitrogen isotope ratios (delta(15)N) were measured in six estuarine species collected from three marshes along this gradient, monthly from June to October between 1997 and 1999. A significant decrease in delta(15)N was found with distance along the estuary for four of the six species. Significant differences were found among monthly isotope ratios for some species. Nitrogen isotope ratios in sea lettuce (Ulva lactuca) increased during the summer season with highest delta(15)N values measured during September and October. This trend was most pronounced at the station receiving the highest nutrient inputs. Elevated delta(15)N values at this station appeared to correlate with seawater ammonia/nitrate concentration ratios. The temporal variations in delta(15)N suggest that care should be taken in species selection and the design of sampling schemes of studies using delta(15)N for monitoring anthropogenic nutrients in aquatic systems. Sampling programs designed to determine long-term trends should consider species that do not show rapid fluctuations in isotope ratios. The mud snail, Nassarius obsoletus, responded this way in the present study. Studies designed to measure short-term changes should include species such as U. lactuca, which rapidly respond to isotope changes. The results from this study also help to establish a baseline for nitrogen isotope values in Narragansett Bay. This information can be used to monitor future trends in nitrogen inputs to this estuary.     

The ECOMAN project: A novel approach to defining sustainable ecosystem function

The ECOMAN was initiated in 2001 by the University of Plymouth, UK, Plymouth Marine Laboratory and the Department of the Environment, Fisheries and Rural Affairs (DEFRA) to address the need for more pragmatic assessment techniques linking environmental degradation with its causes. The primary aim of the project was to develop an evidence-based approach in which suites of easy-to-use, cost-effective and environmentally valid biological responses (biomarkers) could be used together to assess the health of coastal systems through the general condition of individuals. A range of sub-lethal endpoints, chosen to reflect successive levels of biological organisation (molecular, cellular, physiological), was evaluated in common coastal organisms showing different feeding types (filter feeding, grazing, predation) and habitat requirements (estuary, rocky shore). Initially, the suite of biomarkers was used in laboratory studies to determine the relative sensitivities of key species within different functional groups to common contaminants. These results were then validated in field studies performed in a range of ecosystems exhibiting different degrees/signatures of contamination. Here, an example is provided of a field study in the Humber Estuary, UK, which illustrates how multivariate statistical analysis can be used to identify patterns of response to discriminate between contaminated and clean sites. The use of a holistic, integrated approach of this kind is advocated as a practical means of assessing the impact of chemical contamination on organismal health and of ranking the status of marine ecosystems.     

油页岩原位开采生烃过程数值模拟及井位讨论

为研究流体加热技术下油页岩生烃量随时间变化的规律,并找出更适合油页岩原位开采的井位,笔者使用流体模拟软件ANSYS对多井注热和单井注热两种方案,正三角形、正方形和正六边形井组共6种模式建模,进行了温度场模拟。通过MATLAB软件求解油页岩生烃的化学反应动力学方程得到对应时间下的油页岩原位开采的生烃量,并比较不同井位方案的投入产出结果。模拟结果表明,油页岩的生烃量随注热时间的增加而增大,增速先快后慢,注热36个月后增长效果已不明显。多井注热方案下生烃效果优于单井注热,油页岩生烃的净值最大时为六井模式的第20个月,为1 141. 85 t;其次是四井模式的第25个月,为1 034. 63 t;最后为三井模式的第22个月,为878. 95 t。在单井注热模式下,净值最大时刻在第33个月,为390. 00 t。多井注热模式下各模式的能源回报率分别为2. 73、1. 74和2. 05,单井注热模式下能源回报率为1. 418。     

基于Ma PObjects的油气地质信息与评价系统的设计与实现

以往的油气资源评价系统主要是在商用地理信息系统软件平台上开发出来的,其主要缺点就是专业应用模型与系统平台之间不能实现无缝集成。鉴于此,笔者设计实现了基于组件式地理信息系统技术的油气地质信息与评价系统,实现了油气地质信息管理模型与地理信息系统之间的有机结合。利用ESRI公司生产的Ma POb-jects组件,开发出具有通用地理信息系统功能和油气地质信息管理功能的应用系统。该系统可以实现油气地质信息管理、分析和评价等常用功能。