渤海海域渤中19-6潜山气藏成藏要素匹配及成藏模式

为了明确渤海海域渤中19-6潜山千亿立方米气藏的形成过程，基于大量岩心、薄片、测井及地球化学数据，在地质分析的基础上，利用地球化学分析方法和盆地模拟的手段，对其成藏要素及成藏规律进行了系统分析。研究表明：（1）渤中凹陷沙三段烃源岩生气强度普遍超过50×10⁸ m³/km²，晚期持续供烃为渤中19-6潜山气藏的形成提供了充足的物质基础；（2）印支期和燕山期构造运动是渤中19-6潜山构造裂缝型储层和潜山圈闭形成的关键时期，并形成了近源断裂输导体系和远源不整合面输导体系；（3）东营组厚层超压泥岩盖层和潜山较弱的晚期构造活动有利于渤中19-6潜山气藏的保存；（4）“生、储、盖、圈、运、保”六大成藏要素的时空匹配，最终导致了渤中19-6潜山千亿立方米大气田的形成。建立了渤中19-6潜山多洼供烃、多向充注、断裂和不整合联合输导的晚期成藏模式。

Accumulation factor matching and model of Bozhong 19-6 buried hill gas reservoir,Bohai Sea area

The accumulation factors and mechanism of the 100 billion cubic meters gas reservoir in the Bozhong 19-6 buried hill of the Bohai Sea area were studied using geochemical analyses and basin modelling based on a large amount of core,cast thin section,well logging and geochemical data.The results showed the following.(1)The gas generated by the source rocks of the third member of the Shahejie Formation in the Bozhong Sag generally exceeds 5×109 m³/km².The continuous hydrocarbon supply in the late period provided sufficient material for the formation of the Bozhong 19-6 buried hill gas reservoir.(2)The Indosinian and Yanshanian tectonic movements were the key periods for the formation of structural fractured reservoirs and buried-hill traps,and formed a near-source fault transport system and a far-source unconformity transport system.(3)The thick overpressure mudstone cap rocks of the Dongying Formation and the weak tectonic activity in the late period were beneficial to the preservation of the Bozhong 19-6 buried hill gas reservoir.(4)The time-space matching of the six major accumulation factors of“generation,storage,cap rock,trap,migration,and preservation”ultimately led to the formation of a large gas field of 100 billion cubic meters in the Bozhong 19-6 buried hill.A late accumulation model of multi-depression hydrocarbon supply,multi-directional charging,combined fault and unconformity transport was established in the Bozhong 19-6 buried hill.