摘要
烃源岩地球化学特征与潜力评价是油气藏研究体系中的核心要素,对油气资源的勘探与开发具有关键性的指导作用。为系统评价松辽盆地梨树断陷沙河子组烃源岩的生烃潜力,明确其地球化学特征与分布规律,笔者通过岩心观察与测井资料解释,确定了富有机质泥岩段的宏观沉积相与纵向展布;采用一系列地球化学测试手段(总有机碳含量分析、岩石热解分析、干酪根碳同位素组分鉴定、镜质体反射率测试及对饱和烃生物标志化合物气相色谱-质谱测试)对烃源岩的关键参数进行定量表征。研究结果表明:沙河子组沙一下段和沙二中段发育滨浅湖和半深湖-深湖亚相的泥岩沉积,为梨树断陷的主要烃源岩层位,沉积环境为弱氧化-还原条件,沉积演化中心的迁移控制着优质烃源岩的分布。在有机质地球化学特征方面,沙河子组烃源岩表现出较高的有机质丰度,总有机碳质量分数主要分布在1.0%~6.8%之间,平均值为2.5%,绝大多数样品超过了优质烃源岩[w(TOC)≥2.0%]的评价标准,其干酪根类型以Ⅲ型为主,其次为Ⅱ_(2)型,少量样品表现出Ⅱ_(1)型和Ⅰ型特征,热演化程度的评价结果显示烃源岩已达到成熟-过成熟生气阶段(R_(o)>1.3%,平均T_(max)=455.1℃)。综合评价认为,松辽盆地梨树断陷沙河子组主力烃源岩丰富;有机质丰度高,其类型以生气为主;热演化程度高,已进入生气阶段;空间分异明显,具备优良的生烃潜力。
Geochemical characteristics and potential evaluation of hydrocarbon source rocks are the core component of the petroleum system and play a crucial guiding role in the exploration and development of hydrocarbon resources.To systematically assess the hydrocarbon generation potential of source rocks in the Shahezi Formation within the Lishu Fault Depression of the Songliao Basin and to clarify their geochemical characteristics and distribution patterns,the authors utilized core observations and well log interpretations to identify the macro sedimentary facies and vertical distribution of organic-rich mudstone intervals.A series of geochemical analyses(total organic carbon content measurement,rock pyrolysis,kerogen carbon isotope analysis,reflectance in oil testing,and gas chromatography-mass spectrometry of saturated hydrocarbon biomarkers)were employed to quantitatively characterize key parameters of the source rocks.The research results indicate that the lower part of the Sha1 Member and the middle part of the Sha2 Member of the Shahezi Formation are developed with mudstone deposits belonging to coastal-shallow lacustrine and semi-deep to deep lacustrine subfacies,which constitute the main source rock intervals of the Lishu Fault Depression.The depositional environment ischaracterized by weak redox conditions,and the migration of the depositional center controls the distribution of high-quality hydrocarbon source rocks.In terms of organic geochemical characteristics,the source rocks of the Shahezi Formation exhibit high organic matter abundance,with TOC values ranging mainly from 1.0% to 6.8% and an average of 2.5%.The vast majority of samples exceed the quality hydrocarbon source rocks threshold(w(TOC)≥2.0%).The kerogen is predominantly Type Ⅲ,followed by Type Ⅱ_(2),with a few samples exhibiting characteristics of Type Ⅱ_(1) and Type Ⅰ.Thermal maturity assessment indicates that the hydrocarbon source rocks have reached the mature to over-mature gas generation stage(R_(o)>1.3%,average T_(max)=455.1℃).Comprehensive evaluation indicates that the Shahezi Formation in the Lishu Fault Depression of the Songliao Basin is characterized by an enrichment in main hydrocarbon source rocks,high organic matter abundance dominated by gas-prone types,high thermal maturity having entered the gas generation stage,and distinct spatial differentiation,demonstrating excellent hydrocarbon generation potential.
作者
马鑫涛
单玄龙
王舒扬
MA Xintao;SHAN Xuanlong;WANG Shuyang(College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources,Changchun 130026,China;Joint International Laboratory of Future Science,Changchun 130102,China;National Key Laboratory of Deep Exploration and Imaging,Changchun 130061,China)
出处
《世界地质》
2025年第4期608-622,共15页
World Geology
基金
国家自然科学基金青年基金项目(42402167)。
关键词
烃源岩
地球化学特征
烃源岩评价
油气勘探
沙河子组
梨树断陷
松辽盆地
source rocks
geochemical characteristics
hydrocarbon source rocks evaluation
oil and gas exploration
Shahezi Formation
Lishu Fault Depression
Songliao Basin
