澳大利亚北卡那封盆地Rankin台地天然气富集原因初探

Rankin台地是澳大利亚北卡那封盆地重要的天然气和凝析油富集带,在早侏罗世已经抬升,白垩纪中期重新广泛沉积,巨厚的中、上三叠统Mungaroo组三角洲砂岩是该台地重要勘探层系。台地气藏多气源。中、上三叠统Mungaroo组页岩是台地确定的生气岩,形成多套成藏组合。台地也是Barrow—Dampier次盆供烃指向区,由于Barrow、Dampier次盆烃品质不同,造成台地北部的凝析气田比南部的凝析气田含有更多的凝析油。台地天然气富集主要和构造圈闭发育、良好的盖层条件及多气源有关。

Study on Causes of Gas Accumulation in Rankin Platform,North Carnarvon Basin in Australia

Rankin Platform is an important gas-condensate prolific zone in the North Carnarvon Basin.The platform has been uplifted in the Early Jurassic,and became a depo-center again in the Cretaceous.The thick Middle and Upper Triassic Mungaroo Formation is an important exploration target in the platform.Although gas accumulations in the platform have been sourced from multiple formations,the Middle and Upper Triassic Mungaroo Formation is the important proved source rock for gas.This source rock generates gas for quite a few reservoir-source rock combinations.Barrow-Dampier sub-basin is the terminal area for hydrocarbon migration.Because the Barrow and Dampier areas receive slightly different hydrocarbons,and the gas discoveries in the north of the platform have more condensate content than those in the south.Well developed structural traps,good seal and multiple source rocks may account for the concentration of gas accumulation in the platform.