裂谷盆地火山活动与油气藏的形成

摘要

Igneous rocks are distributed in many oil-producing rift basins in the eastern China. A large quantity of basic intrusions, volcanoes and volcanic-clastics are found out in the source and reservoir rocks in the basins of Songliao,Bohai Bay, Erlian, Subei, Nanxiang-Jianghan, Sanshui, Pearl River Mouth, East China Sea and Yinggehai basins, as well as in non-oil-producing basins, such as the Northeast-Inner Mongolia and Ningxia-Gansu rifts.Oil and gas accumulations are commonly with focus on the area of igneous rocks and non-hydrocarbon reservoirs.For example, carbon dioxide reservoirs are also found around the area. Basalt and basaltic clastic-rocks which erupted in depositional environment of source rocks controlled distributions of organic matter, and diabase which intruded in the source rocks was made early and a large quantity of hydrocarbon generated from the source rocks.Meanwhile, multiple traps and oil/gas reservoirs were developed in the area of igneous rocks, because there were large reservoir spaces, good hydrocarbon and non-hydrocarbon charge, as well as good preservation for the traps.Case study is introduced from Dongying depression and other basins.%我国东部裂谷盆地主要生储油层系中常发育有基性浅成侵入岩、火山岩和火山碎屑岩。在火成岩发育区常见油气富集，并伴有非烃气藏。喷发在生油岩沉积环境中的玄武岩及其火山碎屑岩可以改变有机质富集状况；侵入生油层的辉绿岩等可以使局部具有特殊的油气生成能力；火山活动放出的二氧化碳等非烃气体可以直接形成气藏。研究发现，火成岩发育区的生油岩具有早熟和油气生成量特别大等特点；火成岩发育区一般是盆地内构造应力低值区，也是圈闭和油气藏集中发育区。此外，火成岩及相关油气藏具有储集空间发育、油气充注率高、油气保存条件好等优点。以东营凹陷等火成岩发育区为实例，分析并阐明了有关问题。