天然气勘探与开发2025，Vol.48Issue(6)：17-29,13.DOI:10.12055/gaskk.issn.1673-3177.2025.06.002
川西北马角坝观雾山组白云岩储层特征及古油藏成藏潜力
Reservoir characteristics and paleo-oil reservoir forming potential of the Guanwushan Formation dolomites in the Majiaoba area,northwestern Sichuan Basin
摘要
Abstract
To clarify the reservoir characteristics and paleo-oil reservoir forming potential of the dolomites in the middle-upper Devonian Guanwushan Formation in the Majiaoba area,northwestern Sichuan Basin,the reservoir characteristics and hydrocarbon accumulation and evolution process were investigated by integrating field outcrop observations,thin section identification,and organic geochemical analysis.The following results are obtained.First,the dolomite reservoirs in the asphalt-bearing section of the Guanwushan Formation develop dissolution pores,dissolution cavities,and intercrystalline pores with pore diameters ranging from 0.2 to 0.5mm.The asphalt-filled face porosity accounts for approximately 8%,distributed in black ring-shaped or sheets with micropores preserved locally.Second,the characteristics of the reservoir asphalt are highly consistent with those of the Cambrian bio-marker compounds.The saturated hydrocarbon in the asphalt shows an L-shaped distribution,featuring a dominant C23 tricyclic terpane peak,C30 hopane prevalence,and high gammacerane content.This confirms that the natural gas in the Guanwushan Formation mainly originated from the source rocks of the Lower Cambrian Qiongzhusi Formation.Third,the diagenetic evolution and fluid filling of the dolomite reservoirs in this area can be divided into four stages:shallow burial formed microcrystalline-powder crystalline calcite in the Devonian-Carboniferous period;medium-deep burial leads to dolomitization in the Carboniferous-Permian period,resulting in the formation of fine-to medium-grained crystalline dolomites;oil and gas fill the reservoir and asphalt fills the pores in the Late Triassic-Jurassic period;oil and gas cracking in the Cretaceous-Cenozoic period,forming asphalt and releasing natural gas,followed by tectonic movement to modify the reservoir.Fourth,the analysis of hydrocarbon accumulation and evolution shows that the natural gas accumulation in this area has gone through three stages:the formation of paleo-oil reservoirs in the Indosinian period,the formation of paleo-oil reservoirs in the Late Indosinian-Early Yanshanian period,and the formation of gas reservoirs from the Himalayan to the present,generally presenting an evolution model of oil generation in the early stage,gas accumulation in the middle stage,and adjustment in the late stage.关键词
四川盆地西北部/泥盆系中上统观雾山组/白云岩/储层特征/沥青/古油藏Key words
Northwestern Sichuan Basin/Middle-upper Devonian Guanwushan Formation/Reservoir characteristics/Asphalt/Paleo-oil reservoir分类
能源科技引用本文复制引用
卢小兰,李洪奎,孙玮,赵德军,赵涵..川西北马角坝观雾山组白云岩储层特征及古油藏成藏潜力[J].天然气勘探与开发,2025,48(6):17-29,13.基金项目
国家自然科学基金项目"青藏高原东缘晚中—新生代龙门山前陆盆地结构—建造特征研究"(编号:41572111). （编号:41572111）
