辽河盆地西部凹陷稠油分布区地层水化学特征

Geochemical Characteristics and Origin of Formation Water in Western Depression,Liaohe Basin

地层水特征是研究盆地演化及稠油分布的重要因素.稠油在辽河盆地已探明的石油储量中占有重要比例,地层水化学场研究是预测稠油分布的基础,利用地层水地球化学特征和同位素资料研究地层水来源,分析水介质条件对原油降解稠化的影响.研究表明:西部凹陷地层水的矿化度和离子构成受深度控制,具有"垂向流"特征;其化学组成及变化规律的差异反映了不同地区地表水注入强度及局部地下水运动特征的变化,地表水注入强度及运动特征的差异是原油生物降解程度不同的主要原因,地下水的循环特征决定了其化学条件和原油生物降解程度,地表水淋滤作用是降解型稠油发育的必要条件.

The characteristics of formation water are important factors to study the basin evolution and heavy oil distribution.Geochemical studies can facilitate the exploration of heavy oil which dominates the oil reserves in Liaohe basin.Based on the test of formation water and isotope analyses of western depression,the geochemistry and origin of formation water are discussed in this paper.The total dissolved solid（TDS）and chemical compositions are controlled by the buried depth.The formations water shows vertical flow.The differences of chemical compositions of formation water and characters are related to intensity of surface water injection in different areas and local formation water flowing characters which are main reasons of crude oil bio-degradation.The isotope analyses also show that surface water injection is much stronger in Jinzhou,Huanxiling and Lenji areas.The different cycle characters of formation water lead to chemical conditions and crude oil bio-degradation.Surface water leaching is the necessary condition of degradation heavy oil development.