准噶尔盆地腹部侏罗系—白垩系次生油气藏形成机制及分布特征

Genetic mechanism and distribution characteristics of Jurassic-Cretaceous secondary reservoirs in the hinterland of Junggar Basin

准噶尔盆地腹部侏罗系—白垩系发育大量的次生油气藏,以埋藏浅、物性好、建产快、产能高为特点,是寻找高效油气藏的重点探区。利用流体包裹体均一温度分析,结合恢复的埋藏史和热演化史,明确了准噶尔盆地腹部侏罗系—白垩系原生油气藏形成的关键期在早白垩世,次生调整的成藏期在古近纪末期。通过恢复早白垩世(原生油气成藏期)侏罗系的构造,结合成藏要素的时空耦合关系以及油气包裹体丰度、储集层定量颗粒荧光分析,揭示出莫索湾、陆南和陆梁古鼻状构造是侏罗系原生油藏的主要聚集区。综合原生油藏的分布和古近纪末期(次生油气调整期)的构造特征,深入剖析了准噶尔盆地腹部侏罗系—白垩系次生油气藏的成因机制和输导要素,构建了次生油气藏的4类输导体系,明确了各类输导体系的作用区域、成藏层位、目标类型及控制因素,建立了次生油气藏的形成模式。在成藏模式的指导下,结合输导体系的差异性,将侏罗系—白垩系次生油气藏划分为4类成藏区,其中,勘探程度相对较低的石东凸起和石南鼻状凸起是未来寻找高效次生油气藏的重点区带。

A large number of secondary reservoirs are developed in the hinterland of Junggar Basin,characterized by shallow burial depth,good physical properties,fast production and high yield,as a key target for prospecting high-efficient reservoirs.Based on the homogeneous temperature analysis of fluid inclusions,in combination with the recovered burial and thermal evolution history,it has been clarified that the Early Cretaceous was the key period for the development of the Jurassic-Cretaceous primary oil and gas reservoirs in Junggar Basin,and the Late Paleogene was the accumulation period when hydrocarbon were adjusted to secondary reservoirs.By reconstructing the Jurassic structure in Early Cretaceous(primary hydrocarbon accumulation period)and analyzing the spatial-temporal coupling relationship of hydrocarbon accumulation elements,the grains containing oil inclusions and the quantitative grain fluorescence for reservoirs,it has been discovered that Mosuowan,Lunan and Luliang nose-like plunging anticlines were the main accumulation areas of the Jurassic primary reservoir.Based on the distribution of primary reservoirs and the tectonic features in Late Paleogene(secondary hydrocarbon adjustment period),this study deeply analyzes the genetic mechanism and transport factors of the Jurassic-Cretaceous secondary reservoirs in the hinterland of Junggar Basin,constructs four types of transport systems of secondary reservoirs,identifies the action areas,accumulation positions,target types and control factors of various transport systems,and establishes the accumulation patterns of secondary reservoirs.Under the guidance of the patterns and the difference of the transport system,the Jurassic-Cretaceous secondary reservoirs are divided into four types of accumulation areas,of which the Shidong uplift and the Shinan nose-like uplift with relatively low exploration are the key zones of high-efficient secondary reservoirs for future exploration.