东北地区深层侏罗系火山 — 沉积序列与储盖组合及勘探意义 ——以海拉尔盆地侏罗系为例

为揭示东北地区侏罗系火山—沉积序列与储盖组合等地质特征,进一步评价深层油气勘探潜力,本文基于勘探现状,利用露头调查、钻测井对比、岩芯观察、结合地震解释等方法,分析了东北地区侏罗纪盆地构造背景,认为早—中侏罗世和晚侏罗世具有不同的构造环境和盆地性质.早—中侏罗世为受控于蒙古-额霍茨克造山作用的挤压型断陷-坳陷盆地,受到了...

Deep Jurassic volcano- sedimentary succession, reservoir- seal assemblage and their exploration significance in Northeast China: a case study of Jurassic in the Hailar basin

In order to reveal the geological characteristics of Jurassic volcano- sedimentary succession and reservoir- seal assemblage in Northeast China, and to evaluate the exploration potential of deep oil and gas, based on the present status, this paper analyzes the tectonic background of Jurassic basin in Northeast China by means of outcrop survey, drilling and logging comparison, core observation and seismic interpretation. It is proposed that the basin attributes and tectonic settings in the Early to Middle Jurassic and the Late Jurassic were different. In the Early and Middle Jurassic, it was a compressional fault depression basin controlled by the Mongol- Okhotsk orogeny, which was strongly re- formed by the late tectonics. The Late Jurassic is a volcanic faulted basin related to volcanic activities in an intracontinental extensional environment. Late Jurassic volcanic activities were frequent in Northeast China, forming a widely distributed volcano- sedimentary succession. A typical volcano- sedimentary succession developed in the Late Jurassic Tamulangou Formation in the Hailar basin that is characterized by the interbedding of volcanic rocks and sedimentary rocks that display sandstone mudstone- intermediate acid volcanic rocks- sandstone- intermediate basic volcanic rock succession. The rock assemblages in different sag units are quite different. The middle depression belt is mainly composed of volcanic rock and sandstone mudstone, while the peripheral depression is dominated by volcanic rock and glutenite.The lithology of the volcano- sedimentary succession is complex, and the reservoir rock types are diverse. There are mainly three types of lithologic reservoirs: volcanic rock, pyroclastic rock and glutenite. The physical properties of the reservoir are generally low, which belongs to medium- low porosity and extremely low permeability reservoir and tight reservoir.According to the different rock assemblages and oil- gas display of volcano- sedimentary succession, they can be divided into 4 types and 9 subtypes of oil- gas reservoir- seal assemblages. These include sandstone limestone and mudstone reservoir- seal assemblage, volcanic rock internal reservoir- seal assemblage, volcanic sedimentary composite rock reservoir- seal assemblage, and bedrock weathering crust reservoir- seal assemblage.The most favorable reservoir- seal assemblage is sandstone mudstone reservoir- seal assemblage adjacent to hydrocarbon source rock, followed by pyroclastic breccia, tuff and volcanic rock reservoir- seal assemblage of volcanic explosive and eruption facies. The dark mudstone source rocks with moderate to good hydrocarbon generation potential are well developed in volcano- sedimentary succession. The most favorable reservoir- seal assemblages adjacent to hydrocarbon souree rock distributed in the Hongqi sag and the northern Urxun sag are the main exploration fields of deep Jurassic volcano- sedimentary succession.This study can provide clarification and framework for oil- gas exploration of volcano- sedimentary succession in other areas.