盐城朱家墩气田气源及发现意义

Gas source of Zhujiadun gas field, Yancheng basin and its discovery significance .

盐城朱家墩气田是江苏省境内新发现的第三系小型气田。将其所产烃类分为天然气、轻烃、凝析油 3个段份进行的地球化学研究表明 :天然气和轻烃具“腐殖 高熟”特征 ,凝析油具“腐泥 低熟”特征。分析认为 ,天然气主要来自下部的上古生界烃源岩 ,油主要来自上白垩统泰州组中的少量偏腐泥型干酪根。古生界烃源岩在新生代盆地沉降期间“二次生烃” ,生成的天然气通过断裂向上运移至第三系储集。这一气田的发现及其“古生新储”成藏机理进一步拓展了人们对下扬子地区古生界油气勘探的思路。图 6表 4参

Zhujiadun gas field was discovered recently in Jiangsu. The oil gas produced fr om Tertiary sandstone is divided into three fractions: natural gas, light hydroc arbon and condensate. Gas and light hydrocarbon have humic and over mature feat ure, and condensate has sapropelic and low maturity feature geochemically. It is considered that the gas came from the underlying Palaeozoic source rocks, and condensate came from sapropelic kerogen in Upper Cretaceous source rocks. In th e subsidence period of the Cenozoic basin, the hydrocarbons generated secondaril y by Palaeozoic source rocks migrated upward and passed through fault to Tertia ry reservoir. The discovery of this gas field and special forming mechanism of t he gas pool widely opened the mind of the explorers.