延吉盆地石油地质特征初探

延吉盆地在晚华为西期白岗质花岗岩为主的基底上广泛接受了以白垩系为主的中新生代沉积,最大厚度3900m。该盆地具有良好的生、储、盖配置关系和圈团条件。下白垩统大砬子组最厚达2000m。其中暗色泥岩发育,有机质丰度高,转化程度好,是好—较好生烃岩;砂层占地层总厚50％以上,是物性较好的储层;泥岩段横向分布较稳定,是良好的区域盖层。圈团类型主要为岩性、地层圈团,其次为披覆构造和断块圈团。盆地主要勘探目的层是大砬子组,有利远景区为朝阳川凹陷,其次为清茶馆凹陷和德新凹陷,有希望获得中小型油气田。

INQUISITION OF PETROLEUM GEOLOGICAL FEATURE OF YANJI BASIN

Yanji Basin is a Mesozoic intermountainous fault-depressed basin situated at the eastern foot of Changbai Mountains in Northeast Jiling Province. During the process of formation and development, the basin underwent three large scales of magmatic activities as early and late Yenshan and Himalayan, and four evolution stuges:fault-subsided, depressed, shrinkage and uplift stages. Its structural framework was controlled by near NS and EW stretching faults, and characterized by zonatesin EW direction and blocks in NS directions. During Variscian stage, the basin received extensive Meso-Cenozoic sediments in which Cretaceous sediments were the main part.The greatest thickness was 3900m. In late Late Cretaceous, the basin was uplifted and denuded resulted by Himalayan movement. The basin has favourable source-reservoir-cap rock assemblage and trap condition.The Dalazhi Formation in Lower Cretaceous has thick sediments (the max. thickness is about 2000m), and the dark mudstone developed well. Organic abundance and transformation degree of organic matter are high (the average organic carbon is 1.517-2.408%;chloroform extract "A" 0.063-0.072%; the ratio of total hydrocarbon/organic carbon0.232-6.638%;