榆林北部气田山2段地层水化学特征与天然气聚集关系

Relationship between Chemical Characteristics of Formation Water and Natural Gas Accumulation within Shan 2 Member of Shanxi Formation in North Yulin Gas Field

通过对榆林北部气田山2段地层水样品测试结果的统计与分析,可知目的层段地层水以偏酸性为主,矿化度较高,以CaCl_2水型为主,总体反映了地层水封闭条件较好,处于还原的阻滞-停滞水文地质状态,有利于天然气的聚集与保存。地层水化学特征与天然气藏关系研究表明:地层水总矿化度高值区、CaCl_2型水分布区、rNa^+/Cl^-低值区(<0.5)、rMg^(2+)/Ca^(2+)低值区(<0.1)、r(Cl^--Na^+)/2Mg^(2+)高值区(>10)等均与天然气富集区有较好的对应关系。

Based on the statistics and analysis of the testing results of formation water samples from the Shan 2 Member of Shanxi Formation in North Yulin,it＇s known that the formation water of destination layer is mainly acidic and the high mineralized,CaCl2 water type,showing well closed condition of formation water.This formation water is located in the reductive block-stagnation hydrogeology condition,which is conducive to the accumulation and preservation of natural gas.The study of relationship between hydro chemical characteristics and natural gas reservoirs shows that it has a better correspondence with natural gas enrichment area among the total high mineralization degeree of the formation water,the distribution range of CaCl2 type water,the low value area of rNa^＋/Cl^-（〈0.5）and rMg^2＋/Ca^2＋（〈0.1）,as well as the high value area of r（Cl^--Na^＋）/2Mg^2＋（〉10）l.