苏浙皖地区海相油气地质特征及勘探目标的选择

Marine Oil and Gas Geological Characteristics and Exploration Targets in the Jiangsu, Zhejiang and Anhui Provinces

从晚震旦世开始至中三叠世,苏浙皖(下扬子)地区沉积了三套巨厚的海相烃源岩系,即:上震旦统—上奥陶统,石炭系—二叠系、下三叠统海相烃源岩。三套烃源岩热演化特点不同,下古生界烃源岩经历了加里东、印支—燕山期构造阶段的热演化,已达过成熟干气阶段;上古生界烃源岩基本处于生油阶段晚期;大部分三叠系烃源岩处于成熟生油阶段,少数处于未成熟阶段。区内下古生界烃源岩经历了两次成油过程,第一次发生在加里东运动前的盆地沉降阶段,第二次发生在加里东运动后晚古生代陆表海沉积阶段。全区海相油气储盖条件发育,配置有利,经多年油气勘探证实,下古生界油气勘探应立足于苏北地区;上古生界油气勘探除苏北地区外,尚有皖南与浙西地区。中生界海相油气勘探应集中在区内几个发育较好的中生代盆地,如常州、句容、无为、望江盆地等。

From the Later Sinian to the Middle Triassic, 3 series of marine source rocks were deposited, i. e. , the Upper Sinian-Upper Ordovician, Carboniferous-Permian and Lower Triassic in the Jiangsu, Zhejiang and Anhui Provinces. The three hydrocarbon source rocks have different characters of thermal evolution: The Lower Palaeozoic source rocks have undergone structural deformation by the Caledonian and Indosinian-Yanshanian movements, and now at an over-mature dry gas stage; the Upper Palaeozoic source rocks are basically in the late period of oil generation. The great part of the Triassic source rocks is in a mature stage, and only a small part is in an unmature stage. The Lower palaeozoic source rocks in the area have experienced two processes of oil generation. The first was in the basin subsidence stage that was prior to the Caledonian movement. The second took place in the marginal sea deposition stage after the Caledonian movement. Thereservoiring and capping conditions are favourable for marine oil and gas generation. It has been proved through years of oil and gas exploration that oil and gas exploration of the Lower Palaeozoic should be based in the northern Jiangsu area, while for the Upper Palaeozoic, southern Anhui and western Zhejiang should also be considered besides the northern Jiangsu area. The exploration of Mesozoic oil and gas should be focused on some well-developed Mesozoic basins, such as Changzhou, Jurong, Wuwei and Wangjiang.