准噶尔盆地东道海子凹陷二叠系下乌尔禾组陆相页岩气形成富集条件及主控因素  

Enrichment conditions and main controlling factors of continental shale gas in the Permian Lower Wuerhe Formation in the Dongdaohaizi Sag,Junggar Basin

作　　者：王大兴 胡海燕 邹佳群 王涛 朱根根 陈笑宇 梁烁 WANG Daxing;HU Haiyan;ZOU Jiaqun;WANG Tao;ZHU Gengen;CHEN Xiaoyu;LIANG Shuo(College of Resources and Environment Yangtze University,Wuhan 430100,China;School of Geosciences,Yangtze University,Wuhan 430100,China;College of Geology and Mining Engineering,Xinjiang University,Urumqi 830047,China)

机构地区：[1]长江大学资源与环境学院,武汉430100 [2]长江大学地球科学学院,武汉430100 [3]新疆大学地质与矿业工程学院,乌鲁木齐830047

出　　处：《地质科技通报》2024年第4期98-112,共15页Bulletin of Geological Science and Technology

基　　金：中国石油化工股份有限公司重大科技资助项目“准噶尔盆地及周缘矿权战略选区及评价研究”(P21086-4)。

摘　　要：为探明准噶尔盆地二叠系下乌尔禾组页岩气富集条件及主控因素,以东道海子凹陷下乌尔禾组为研究对象,通过野外地质观察、录井、测井、地震等资料的收集,结合总有机碳含量测定、X衍射全岩分析、岩心观察、气体吸附(N_(2)、CO_(2))等手段,对下乌尔禾组页岩的分布特征、有机质发育特征、储层特征及含气性特征进行了研究。结果表明:(1)下乌尔禾组页岩总有机碳含量(w(TOC))较高,平均1.58%;有机质类型以Ⅱ_(2)型和Ⅲ型为主;镜质体反射率Ro平均1.46%,处于成熟阶段;烃源岩厚度平均75 m,烃源岩较好,生气潜力大。盆地模拟结果表明下乌尔禾组页岩含气量较好,平均1.89 m^(3)/t。(2)页岩储集层粒内孔和微裂缝较为发育;气体主要吸附于微孔和介孔;孔隙度均值6.10%,渗透率均值为0.27×10^(-3)μm^(2),有利于页岩气的聚集。(3)页岩黏土矿物体积分数较高,均值29.6%,能提供较高的比表面积,增加页岩的气体吸附能力;脆性矿物体积分数均值50.9%,压裂改造性良好。(4)页岩储层压力系数较大,均值为1.58,具有良好的保存条件。结合区域构造—沉积环境以及地化参数的分析表明,东道海子凹陷下乌尔禾组页岩气成藏的主控因素包括地化参数和保存条件,其中有机质热演化成熟度高、页岩厚度大、w(TOC)高、良好的保存条件等是影响页岩气富集的关键因素。基于上述条件,提出东道海子凹陷页岩气勘探开发有利区位于凹陷的腹部偏东北斜坡地区。该研究成果揭示了东道海子凹陷下乌尔禾组页岩气富集条件及主控因素,对准噶尔盆地腹部地区深层油气勘探具有借鉴意义。[Objective]To explore the enrichment conditions and main controlling factors of shale gas in the Lower Wuerhe Formation of the Permian System in the Junggar Basin,the Lower Wuerhe Formation in the Dongdaohaizi Sag was selected as the research object.[Methods]Based on the data of outcrop,core,well logging,well-calibrated seismic reflections and the technologies of total organic carbon(TOC)content determination,whole-rock Xray diffraction,gas adsorption(N_(2),CO_(2)),the distribution characteristics,organic matter development characteristics,reservoir characteristics,and gas bearing characteristics of the Lower Wuerhe Formation shale were studied.[Results]The results show that:(1)The organic matter of the Lower Wuerhe Formation shale is dominated byⅡ_(2) andⅢtypes and shows an average TOC content of 1.58%.The average vitrinite reflectance(Ro)of organic matter is 1.46%,which indicates the mature stage.The average thickness of the source rock is 75 m.Summarily,the source rock is good and has a high gas potential.The basin simulation results show an average shale gas content of 1.89 m^(3)/t in the Lower Wuerhe Formation.(2)The pores and microfractures in shale reservoirs are highly developed,and gas is primarily adsorbed in micropores and mesopores.The average porosity and permeability are 6.10%and 0.27×10^(-3)μm^(2) respectively,which are favourable for shale gas accumulation.(3)The shale has a high clay mineral content,with an average of 29.6%,providing a significant specific surface area and enhancing the gas adsorption capacity of the shale.Additionally,the average brittle mineral content is 50.9%,indicating good frackability.(4)Moreover,the shale reservoir exhibits a relatively large pressure coefficient of 1.58,indicating the favourable conservation conditions.The analysis of the regional tectonic-sedimentary environment and geochemical parameters indicates that the main factors controlling shale gas accumulation in the Lower Wuerhe Formation of the Dongdaohaizi Sag are geochemical parameters and preservat

关 键 词：陆相页岩 页岩气富集 主控因素 下乌尔禾组 东道海子凹陷 准噶尔盆地 

分 类 号：P618.13[天文地球—矿床学]