摘要
莺歌海盆地是一个新生代形成的富含天然气的沉积盆地，其上第三系及第四系下部沉积岩系中发育有大面积连片成带的泥拱背斜构造，上第三系莺－黄组是浅埋的最主要天然气储集层，所产气体普遍含有CO2，有一部分气井产高浓度的CO2，高浓度CO2天然气主要分布在中央泥失构造带。分析了莺－黄组所产天然气的地球化学特征，并考虑到南中国海地区在新生代分别经历了4期明显的火山作用，热作用和裂谷作用，莺歌海周边地区广泛发育有中酸性火山岩系，盆地中央上第三系和第四系下部发育有大面积的高温高压泥拱，盆地第三系海相沉积岩系中普遍含有碳酸盐矿物，莺－黄组中下部及梅山组中钙质含量＞10％，中央泥拱带具有高地温（＞4℃／100）的地质地球物理特征，认为莺歌海盆地的莺－黄组中CO2是中中新世和第四纪初期由盆地基底花岗岩系热脱气作用和2000－5000m及其以下第三系沉积岩系中的碳酸盐矿物热分解作用或低温水解作用联合贡献的，CO2的贡献量分别为15％－100％和0－85％。
Yinggehai basin is a Cenozoic sedimentary basin with rich gas. The central part is developed
large squars mud diapiric structures in Neogene and Lower Quaternary sedimetary system. The
Ying-Huang Formation of Neogene is an important shallow gas reservoir . The gas is with CO2
popularly,and has high concentration of CO2 in part of the reservoir. High percentage CO2 accumu
late in the central mud diapir domes mainly.
The geochemical characteristics of the gas are following,CH4:5.23%~90. 98% ,CO2:0.94%
~93.01%,N2:1.15%~58. 31%;C2+:0. 43%~3.48% and C6+:0.11%~0.57%;Combining geo
chemical characteristics with the geological and geophysical characteristic of the quadruplex signifi
cant thermal action in Cenozoic era in the South Sea of China,the acidic-neutral igneous rocks are
widespread in the periphery of Yinggehai Basin,high pressure and high temperature mud diapris in
the centre of the Basin in wild,the carbonate material are widespread in the Tertiary marine sedi- ment, the calcarious content>10% in mid-lower Ying-Huang Formation and Meishan Formation,
and the geothermal gradient in the central mud diapiris>4℃/100m,the autor sets forth the CO2 in
Ying-Huang Formation of Yinggehai Basin are contributed by both the basement granide thermal
outgassing in the bottom of basin and degassing of carbonate material (including carbonate cement)
thermal decomposition or low temperatue hydrolysis from 2000-5000m and below in Tertiary sys
tem. Percentages of the outgassing and degassing to CO2 are 15%~100% and 0-85%,respective-
ly.
出处
《中国海上油气（地质）》
1997年第2期100-105,共6页
China Offshore Oil and Gas(Geology)
