PETROPHYSICS OF LOWER CRETACEOUS PLATFORM CARBONATE OUTCROPS IN PROVENCE (SE FRANCE): IMPLICATIONS FOR CARBONATE RESERVOIR CHARACTERISATION

High resolution petrophysical analyses were carried out on Urgonian (Lower Cretaceous) carbonates from outcrops in Provence, SE France. Porosity and permeability were measured on 541 plug samples selected from grain‐supported carbonates analogous to those in the age‐equivalent Shu'aiba and Kharaib Formation reservoirs in the eastern Arabian Plate. The sampling strategy allowed property heterogeneities from centimetre to kilometre scales to be investigated, as well as correlations between porosity and permeability in several different reservoir rock types. Property spatial modelling sensitivity analyses were also undertaken. The relative abundance of microporosity, grain size and sedimentary‐diagenetic anisotropy were the main geological parameters which controlled the petrophysical characteristics of the grainstones studied. Increasing microporosity decreased permeability but resulted in an increase in the homogeneity of the reservoir rocks and therefore in their predictability. An increase in grain size, from fine sand to gravel, and in the amount of intergranular pores, enhanced permeability significantly but resulted in a decrease in the homogeneity (and therefore predictability) of the reservoir rock. At a plug scale, poro‐perm relationships are very good and can be used predictively for fine grainstones dominated by microporosity; but relationships are moderate to weak for coarse rudstones with mixed pore types, including intraskeletal pores. In grainstone units, weak sedimentary anisotropy, such as decametre‐scale cross‐bedding, did not prevent the prediction of the horizontal property distribution from vertical data over a few hundreds of metres. In these units, the lateral correlation of rock properties follows periodic variograms with a 7 m wavelength. The lateral distribution of properties in coarse‐grained and heterogeneous rudstones with complex pore types and intense sedimentary heterogeneities, such as channel structures, was however more difficult to predict from a vertical data set. Upscaling poroperm data from plug scale to reservoir scale is linear in the case of grainstones with intergranular microporosity, but is non‐linear in the case of skeletal rudstones with coarser pore types including skeletal porosity.     

花马、北大二池考

花马、北大二池相邻,池盐生产历史悠久,向为边地番、汉民户生计之所赖,在西北边防和盐课收入中占有重要地位。本文根据有关文献资料和考古资料,对二池沿革试作探讨。笔者认为,花马池,汉代称为"龟兹盐池",北魏称为"黑盐池",唐宋称为"乌池",明代以后称"花马池";唐宋时期称北大池为"白池",明、清时期称为"锅底池"和"西黑图池",清末以后始称"北大池"。     

Gastropod communities, vegetation dynamics and landscape changes along an old-field succession in Provence, France

Studies about the relationships between land snail communities and landscape are scarce. The abandonment of many cultivated lands in Provence since the end of the last century gives us the opportunity of an analysis of the organisation pattern of gastropod communities in relation to the recent history and the present day structure of a Mediterranean landscape. The dynamics of a 40 ha landscape, mapped on a raster mode, was studied using cadaster data for seven periods between 1890 and 1990. These data were computed using MCA and PCA. Both floristic and malacological relevés were made at a scale of one grid cell. At the stand level, the patterns of gastropod communities are strongly correlated with the vegetation structure and composition. At the landscape level, the analysis of gastropod communities permits a very good perception of the present day landscape structure, as well as insight into the recent landscape history. However, even if the fits obtained are good, they should be improved in order to take into account scale dependences of snail communities.     

河北省参考作物蒸散量时空变异性分析

基于河北省17个气象站点53年的逐日气象数据,利用FAO推荐的Penman-Monteith公式计算参考作物蒸散量(ET_0),分析其空间特征和时间变异性。结果表明,全省ET0不同时期分布均存在明显地区性差异,总体西部普遍大于东部;多年月ET0呈开口向下二次抛物线形分布;全省ET_0对相对湿度的敏感性最强,均值达-0.77;53年来ET_0有明显减小趋势,倾向率为-0.028mm/10a;通过0.001相关性检验分析发现,全省ET_0与相对湿度、风速、日照小时数呈极显著性相关,与气温相关性不显著,其变化主要受相对湿度和风速的影响。