渤中坳陷及其邻区第三系沉积特征和油气勘探潜力分析

TERTIARY SEDIMENTOLOGY AND HYDROCARBON POTENTIAL IN BOZHONG DEPRESSION AND ITS ADJACENT AREA

渤中坳陷及其邻区第三纪构造-沉积演化经历了裂陷和裂后拗陷两大阶段,形成了下断、上拗的双层结构.早第三纪的多幕裂陷沉降使区内沉积了沙三段、沙一段和东三段-东二段下部(东下段)3套优质湖相烃源岩,裂陷-拗陷阶段的3次主要构造沉降导致了3套区域盖层的沉积,短源沉积-内源沉积一远源沉积的沉积充填演化造就了多种类型的储集体,所发育的深层、中深层和浅层3套储盖组合为渤中坳陷及其邻区油气的聚集成藏创造了得天独厚的有利条件.

In Bozhong depression, there are two stages, i. e. rifting and sagging, in Tertiary tectonic-sedimentary evolution, resulting in a two-layered framework of stratigraphy. During multiple episodes of Paleogene rifting subsidence, three sets of excellent lacustrine source rocks may be deposited: Lower Dongying Formation, Sha-I and Sha-IⅡ Members. The three episodes of tectonic subsidences from the rifting stage to the sagging stage can lead to deposition of three regional seals, and various reservoirs are created in a sedimentary evolution from proximal-supplying, internal-supplying to distal-supplying. All these have constituted three, i. e. deep, middle and shallow reservoir-seal asssemblages, which may provide a unqiue favourable environment for hydrocarbon accumulation in Bozhong depression and its adjacent areas.