摘要
晚印支—燕山运动是影响下扬子海相成烃—成藏最重要的构造事件。以此为界,烃源岩的演化分为早期生烃和晚期(二次生烃)2个阶段。与此对应,下扬子海相经历了加里东期、印支期、喜马拉雅期3期成藏,不同成藏期烃源构成具有明显的差异。对于喜马拉雅期的晚期成藏,有效烃源主要来自于二叠系和志留系烃源岩的二次生烃和古油藏(灶)的裂解供烃。借助于烃源岩热史分析,分别求取印支运动之前(T2末)和断陷盆地叠置之后(E末)烃源岩的成熟度(Ro),后期形成温度补偿且T2末Ro较低(小于1.3%)的烃源岩范围是二次生烃的有利区。对于古油灶,根据T2末的下古生界顶面古流体势和有利储层分布范围,推断油气的运移指向和有利聚集区,然后结合燕山运动后志留系泥岩盖层的保存情况,预测燕山运动后古油藏赋存的有利范围。通过上述途径实现对有效烃源的定位。临近有效烃源岩(灶)的范围是晚期成藏的有利地区。
Tectonic activity in the Late Indosinian-Yanshanian period was the most important event for marine hydrocarbon generation and accumulation in the Lower Yangtze area. The evolution of source rocks could be classi- fied into early and late （secondary） stages of hydrocarbon generation. Accordingly, 3 hydrocarbon accumulations inmarine sequences in the Lower Yangtze area were formed in the Caledonian, Indosinian and Himalayan periods, respectively. There were obvious differences among hydrocarbon sources in the different accumulation periods. The late hydrocarbon accumulation in the Himalayan period was mainly sourced from the secondary generation of the Permian and Silurian source rocks and the thermal cracking of ancient oil pools. The thermal history of the source rocks indicates that the potential location for secondary hydrocarbon generation was limited to the area where Ro was 〈 1.3% at the end of the Middle Triassic. Oil and gas migration direction and possible accumulations were identified in the light of paleo-fluid potential for the top of the Lower Paleozoic sequence. Combined with the analysis of preservation conditions of the Silurian mudstone seals after the Yanshanian movement, the distribution of oil accumulations could be predicted. Therefore, the effective source rocks might be determined and the potential late accumulations that were formed in their nearby areas identified.
出处
《石油实验地质》
CAS
CSCD
北大核心
2016年第1期9-14,共6页
Petroleum Geology & Experiment
基金
国家自然科学基金项目(41302118)
中国石化重大先导项目(G5800-13-ZS-TY)资助
关键词
有效烃源
晚印支—燕山运动
海相
成烃—成藏
烃源构成
下扬子地区
effective sources
late Indosinian-Yanshanian movement
marine sequence
hydrocarbon generation and accumulation
composition of hydrocarbon source
Lower Yangtze area
