摘要
塔里木盆地厚达 5～ 7km的海相寒武、奥陶系 ,可划分出下、中寒武统和中、上奥陶统两套工业性烃源岩。油源对比证实 :盆地目前保存下来的海相成因工业性油藏 ,主要来源于中上奥陶统泥灰岩。正是因为塔里木盆地比四川、鄂尔多斯盆地多了一套中等成熟的中上奥陶统油源岩 ,所以能够找到海相油田。笔者认为 :海相工业性烃源岩不必很厚 ,但w (TOC)应≥0 .5% ,碳酸盐岩要含泥质 ;海相源岩往往并不发育在凹陷中心 ,而发育在 4种有利沉积相带上 ;碳酸盐岩具有“双重母质”的特点 ,浮游藻类偏油 ,底栖藻类偏气。海相源岩的形成模式有“保存模式”和“生产力模式”两种 ,分别对应于塔里木寒武系和中上奥陶统烃源岩。塔里木古生代克拉通早期活动、晚期稳定、持续降温的演化史 ,有利于海相油气的多期成藏和晚期保存。
Two sets of commercial marine source rocks—the Lower Middle Cambrian and the Upper Middle Ordovician can be identified from the marine Cambrian and Ordovician series with a thickness of 5～7km in the Tarim basin. The correlation between oil and source proved that the preserved commercial oil reservoirs of marine origin in the Tarim basin are mainly generated from the marl of the Middle Upper Ordovician. The occurrence of marine oil reservoirs in Tarim basin is largely due to the development of a set of moderately matured Middle Upper Ordovician source rock in the basin, which are yet not found in Sichuan and Ordos Basins. The authors believe that the commercial marine oil source rocks are not necessarily very thick, but they should be characterized by w (TOC)≥0.5%; They developed usually in the four favorable sedimentary facies instead of the center of depressions. The carbonate source rock must be argillaceous and is of “Dual precursors” —planktonic algae and benthonic algae. The Cambrian and Middle Upper Ordovician marine source rocks in Tarim basin can be correlated respectively with the two proposed formation models of marine source named as “Preservation Model” and “Productivity Model”. The early active and late stable tectonic movements as well as the continuous cooling down of Tarim Paleozoic Craton make the basin rather favorable for the multi stage reservoir formation and the late stage preservation of the marine oil and gas.
出处
《地学前缘》
EI
CAS
CSCD
2000年第4期534-547,共14页
Earth Science Frontiers
基金
国家"九五"重点科技攻关资助项目(96-111-01-03)
关键词
塔里木盆地
中国海相生油
烃源岩
油气源对比
生油岩母质
成熟度
盆地演化
Tarim basin
marine oil generation in China
hydrocarbon source
oil-gas/source correlation
organic matter of source rock
maturity
basin evolution
