西伯利亚北极地区含油气盆地的水文地球化学特征

摘要

通过对过去40年收集的西伯利亚北极地区水文地球化学数据进行分析及综合解释,对数据进行了分类、评价和统计分析,评估区域背景值和异常值,估算水源之间接近程度的各种相关系数.西伯利亚沉积盆地的古水文地质重建表明,油气藏的水体有3种成因类型:①海相沉积过程中形成的水体;②渗入盆地内并经历了各个地质时期表生作用的大气降水成因的水体;③烃类混合物冷凝形成的水体.油气藏的水文地球化学模式受控于水-岩-气-有机质体系漫长的地质演化过程.西伯利亚北极地区沉积盆地内分布总矿化度为0.2～350.0 g/L的含氯化钠-碳酸氢盐、氯化钠、氯化钙地下水和其他类型的地下水.通过对西伯利亚北极地区地下水的对比分析,发现含有氯化钠组分的样品总矿化度超过250 g/L,表明卤水的形成与蒸发岩的浸出有关.水文地球化学数据分析显示,地下水的成分随其演化而发生非常大的变化,阿纳巴尔—拉普帖夫、西西伯利亚等盆地中生界的地下水处于其化学演化的初始阶段.%The available hydrogeochemical data collected over the past four decades in Siberian Arctic areas were analyzed and interpreted comprehensively for the first time,through data ranking,evaluation and analysis,systematic estimation of region,altitude background and abnormal value,and calculation of element molar ratio,different kinds of correlation coefficients in water proximity were estimated.Paleohygdrogeological reconstructions of the Siberian sedimentary basins suggest the presence of three water genetic types in petroleum deposits:(1) Waters that formed during marine sedimentation,(2) Waters of meteoric origin that infiltrated the basin and were involved in supergene processes in the geological past,(3) Waters produced by condensation from a hydrocarbon mixture.Hydrogeochemical patterns of petroleum deposits are controlled by the long geological evolution in the water-rock-gas-organic matter system.Sodium-chloride bicarbonate,sodium chloride,calcium chloride groundwaters,and other types of brines with the total salinity of 0.2-350 g/L are distributed in the Siberian Arctic sedimentary basins.Comparative analysis of groundwaters and brines in the Siberian Arctic revealed a group of sodium chloride water samples had a total salinity of over 250 g/L,suggesting the formation of the brine was related to leaching of evaporite rock.Hydrogeochemical data indicate that composition of the brine has varied dramatically with their evolution.Mesozoic groundwaters and brines of Anabar-Laptev basin and West Siberia existed only in the beginning of their chemical evolution.