地层流体化学成分与天然气藏的关系初探
———以鄂尔多斯盆地中部大气田为例

The Preliminary Discussion on Relationships Between Chemical Compositions of Formation Fluid and Natural Gas Reservoirs - A Case Study of Central Large Gas Field in Erdos Basin

李贤庆^{1 ,2},侯读杰¹,唐友军¹,胡国艺³,张爱云⁴

Li Xianqing, Hou Dujie, Tang Youjun, et al

1. 江汉石油学院分析测试研究中心,2. 中国科学院广州地球化学研究所,3. 石油勘探开发科学研究院廊坊分院,4. 中国地质大学能源地质系

Jianghan Petroleum Institute , Hubei 434102 ,P. R. China

以鄂尔多斯盆地中部大气田为实例,从流体地球化学角度对地层流体(特别是地层水) 化学成分与天然气藏的关系进行了研究,初步提出了天然气藏分布区的综合地球化学判识指标。研究认为,地层流体化学成分与天然气藏的关系密切,地层水总矿化度高值区( >150g/ L) 、CaCl₂ 水型分布区、r_Na+ / r_Cl^- 低值区( ≤0. 3) 、r_Cl^- / r_{Mg^{2 +}} 高值区( > 15) 、r_{Mg^{2 +}} / r_{Ca^{2 +}}低值区( ≤0. 2) 、有机酸高值区( > 40 mg/ L) 、酚含量高值区( > 2. 0 mg/ L) 及可溶气态烃含量高值区都与天然气藏富集区具有较好的对应关系。因此,利用地层流体的地质地球化学综合研究,可为天然气藏富集区(或含气区) 的判识和找寻提供新的资料和依据。

The relationship between chemical composition of formation fluid and the formation of natural gas reservoir is a subject that is always ignored by people and ought to be further studied. This paper takes the central large gas field in Erdos Basin as a study case. The relationships between chemical compositions of fluid (especially formation waters) and the formation of natural gas reservoirs are thus studied. Geochemical identification index of natural gas enrichment area (or gas prospect area) is preliminary put forward. It’s suggested that there are close relations between chemical compositions of formation fluids and natural gas reservoirs. While there are high total dissolved solid( > 150 g/ L) ,CaCl2 type ,low rNa+ / rCl- ( ≤0. 3) ,high rCl- / rMg2 + ( > 15) ,lowrMg2 + / rCa2 + ( ≤0. 2) ,high organic acids ( > 40 mg/ L) ,highphenols content ( > 2. 0 mg/ L ) and high dissolved gaseous hydrocarbon in formation fluids ,there may be a beneficial gas enrichment area. Therefore , by using the comprehensive studies of geologic geochemistry of formation fluids , it may provide with new data and evidences to identify & search for natural gas enrichment area (or gas prospect area) .