松辽盆地东南隆起区下白垩统层序地层格架及油气成藏规律

LOWER CRETACEOUS SEQUENCE STRATIGRAPHIC FRAMEWORK AND HYDROCARBON ACCUMULATION IN THE SOUTHEAST RISE, SONGLIAO BASIN, CHINA

松辽盆地东南隆起区具有典型的下断上坳沉积特征,区内Tg—T2反射界面之间自下而上可以划分为5个层序,层序Ⅰ大体相当于火石岭组,层序Ⅱ大体相当于沙河子组,层序Ⅲ大体相当于营城组,层序Ⅳ大体相当于登娄库组,层序Ⅴ大体相当于泉头组。烃源岩主要为层序Ⅱ“水进体系域和高水位体系域”的半深湖相泥岩,主要目的(储集)层为层序Ⅴ低水位体系域的辫状河道砂体。生、储、盖、圈、运和保在时空上的有机组合,使松辽盆地东南隆起区的农安—德惠地区的油气聚集南北成带,东西分隔有别,西部形成了断背、背斜型有利油气成藏带,中部形成了断块、断鼻型较有利油气成藏带。

The Southeast Rise, a sub-order tectonic unit of the Songliao Basin, was a typical sedimentary area with a fault depression in earlier stage and a depression in later stage. Five sequences could be distinguished based on reflection boundaries of T g—T 2. The sequence I was correspondent to the Early Cretaceous Huoshiling Formation, sequence II to the Shahezi Formation, sequence III to the Yingcheng Formation, sequence IV to the Denglouku Formation and sequence V to the Quantuo Formation, respectively. The source rocks consisted of mudstones with semi-deep lacustrine facies, developed in “TST+HST” of sequence II. The main reservoirs were braided fluvial sandbody developed in LST of sequence V. There was an obvious zonation for hydrocarbon accumulations in the south and north as a result of combination of hydrocarbon generation, accumulation, entrapment and preservation. Anticline oil reservoirs were mainly developed in the west, and fault block ones were in the central part, respectively, in Nongan-Dehui area.