饶阳凹陷留西—留北地区新近系地层水特征及其与油气分布的关系

以冀中坳陷饶阳凹陷新近系油气分布最富集的留西—留北地区为研究对象,通过对该区新近系地层水及其与油气分布关系的系统分析,明确了新近系地层水的水化学类型及矿化度分布特征,揭示了该区新近系地层水的地球化学特征异常与油气运移、油气分布的内在关系。结果表明：留西—留北地区新近系整体上发育低矿化度的NaHCO3型地层水,地层水矿化度具有由西向东、由北向南逐渐增加的趋势,同时水化学类型由HCO3--Cl--Na＋型过渡为Cl--HCO3--Na＋型;在油源和断裂条件良好的条件下,新近系地层水异常与油气分布具有良好的对应关系,新近系油气主要在地层水矿化度高于背景值、水化学类型异常及油源断裂发育的地区富集,同时新近系高矿化度Na2SO4型或MgCl2型地层水对油气由深向浅的运聚特征具有重要的指示作用。

Characteristics of Neogene Formation Water and Its Response to Hydrocarbon Distribution in Liuxi-Liubei Area of Raoyang Sag

Neogene formation water and its response to hydrocarbon distribution in Liuxi-Liubei Area, in which hydrocarbon was richest in Raoyang Sag of Jizhong Depression, were analyzed; distribution characteristics of salinity and hydrochemical type of Neogene formation water were discussed; the internal relationship between abnormal geochemistry characteristics of Neogene formation water and the migration and distribution of hydrocarbon in the area was revealed. The results showed that Neogene developed NaHCO3 type of formation water with low salinity in Liuxi-Liubei Area, the salinity of formation water increased gradually from west to east and from north to south, and the hydrochemical type developed from HC03-C1 -Na＋ to C1 -HCO~--Na＋ ; the corresponding relationship between abnormal Neogene formation water and hydrocarbon distribution was fine under the condition of good oil source and fault; Neogene hydrocarbon was usually rich in the area with high salinity of formation water, abnormal hydrochemical type and source fault developed, and the Na2SO4 or MgC12 type of Neogene formation water with high salinity indicated the characteristics of migration and accumulation from lower to upper.