层序格架下构造—沉积分异对页岩气储层特征的控制——以四川盆地西南部筇竹寺组为例  

Control of the Pattern of Tectonic-Depositional Differentiation on Shale Gas Reservoir Characteristics Within a Sequence Stratigraphic Framework:A case study from the Qiongzhusi Formation in the southwestern Sichuan Basin

作　　者：刘瑞崟 周文[1,2] 徐浩[1,2] 周秋媚[1,2] 曹茜[1] 高雯璐 宋威国 蒋柯 蒲飞龙 杨国梁 尚福华 LIU RuiYin;ZHOU Wen;XU Hao;ZHOU QiuMei;CAO Qian;GAO WenLu;SONG WeiGuo;JIANG Ke;PU FeiLong;YANG GuoLiang;SHANG FuHua(College of Energy,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology),Chengdu 610059,China;School of Mining Technology,Inner Mongolia University of Technology,Hohhot 010051,China)

机构地区：[1]成都理工大学能源学院,成都610059 [2]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059 [3]内蒙古工业大学矿业学院,呼和浩特010051

出　　处：《沉积学报》2023年第5期1478-1494,共17页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41972137,42002157);四川省自然科学基金项目(2021YJ0349);国家留学基金委项目(202108510120)。

摘　　要：为明确层序格架下不同构造—沉积分异格局内筇竹寺组富有机质页岩展布特征和页岩气储层差异特征。基于T-R层序模型划分筇竹寺组层序并建立层序地层格架,在层序格架约束下,对筇竹寺组岩心、测井、地球化学及孔隙结构资料进行分析。研究表明,筇竹寺组可识别及划分出4个层序界面与3个三级层序,各层序厚度表现为从绵阳—长宁裂陷的裂陷中心向裂陷外缘逐渐减薄,其中SQ2-RST的厚度在JS1—JY2地区大幅减薄,SQ3厚度减薄范围扩展至Z4—JS1一线。明确了层序格架内不同构造—沉积分异格局下筇竹寺组页岩气储层特征:TOC含量表现为TST大于RST,裂陷中心大于过渡带大于裂陷外缘;矿物含量表现为SQ1和SQ2以长石和石英为主,而SQ3以黏土和石英为主,过渡带的石英和黄铁矿含量高于裂陷外缘;孔隙度表现为过渡带大于裂陷外缘,SQ1低于SQ3和SQ2,且SQ1有机质孔发育较差。绵阳—长宁裂陷的构造—沉积分异作用控制了筇竹寺组沉积时期的地形地貌和水体深度,导致不同层序和构造—沉积分异格局下沉积水体的氧化还原条件、古生产力水平、自生矿物形成环境以及底板封闭性存在差异,并进一步影响了有机质的富集、矿物组分含量和孔隙发育特征。To clarify the characteristics of organic shale distribution and shale gas reservoir in different tectonicdepositional differentiation patterns under the sequence framework,we examined the stratigraphy of the Qiongzhusi Formation in the southwestern Sichuan Basin.Based on the transgressive⁃regressive sequence model,the sequence of the Qiongzhusi Formation was divided,and the sequence stratigraphic framework was established.Under the con⁃straints of the sequence framework,core,logging,geochemical,and pore structure data of the Qiongzhusi Formation were analyzed.The characteristics and influencing factors of the Qiongzhusi Formation shale gas reservoirs under dif⁃ferent structural-sedimentary differentiation patterns were identified.The study shows that four sequence boundaries and three third-order sequences can be classified in the Qiongzhusi Formation.The thickness of each sequence is gradually reduced from the center to the outer edge of the Mianyang-Changning intracratonic rift owing to tectonicdeposition differentiation.The thickness of strata sequence(SQ)2 regressive systems tract is significantly thinned in the JS1⁃JY2 area,and the thinning of SQ3 extends to the Z4⁃JS1 area.The shale gas reservoir characteristics of the Qiongzhusi Formation under different tectonic-deposition differentiation patterns and the sequence framework are clar⁃ified:the total organic carbon content shows that transgressive systems tract is larger than regressive systems tract,and the center of the rift is larger in the transition zone than at the outer edge of rift;the mineral content shows that SQ1 and SQ2 are dominated by feldspar and quartz,but SQ3 changes to be dominated by clay and quartz.The quartz and pyrite content in the transition zone is higher than the outer edge of the rift;the porosity shows that the transition zone is larger than the outer edge of the rift,SQ1 is lower than SQ3 and SQ2,and the organic matter pore of SQ1 is poorly developed.The tectonic-deposition differentiation of the Mianyang-Changning

关 键 词：筇竹寺组 页岩气 层序地层 构造—沉积分异 储层特征 

分 类 号：P618.13[天文地球—矿床学]