摘要
四川盆地上二叠统吴家坪组沉积相横向变化大,川北地区发育一套海相黑色页岩。以川东北峰探1井为研究对象,通过岩石学、地球化学分析、扫描电镜、低温氮气吸附和甲烷吸附等方法,对页岩气地质条件进行研究。研究结果表明:①在川东北地区吴家坪组发育两套黑色页岩,吴二段发育一套滨岸潮坪相黏土质灰黑—黑色页岩,脆性指数低,可压裂性弱;吴三段发育一套深水陆棚相黑色硅质、钙质页岩,脆性指数高,可压裂性强。②吴二段页岩有机质丰度平均值为1.41%,黑色页岩厚度较薄,有机碳含量大于2%,有机质类型为Ⅲ型;吴三段页岩有机质丰度平均值为3.52%,黑色页岩厚度26 m,有机碳含量大于2%,有机质类型为Ⅱ1—Ⅱ2型,均达到过成熟阶段。③吴家坪组二段页岩储集空间主要以黏土矿物之间粒间孔和微裂缝为主,有机质孔相对不发育,孔隙体积0.0066 cm3/g,以介孔为主、微孔次之,含气性为1.5190 cm3/g;吴家坪组三段页岩储集空间主要以有机质孔为主,孔隙体积平均为0.0141cm3/g,孔隙以微孔为主、介孔次之,含气性平均为2.3070 cm3/g,孔隙结构和含气性受有机质丰度控制明显,矿物组分对其没有明显控制作用。④吴二段页岩气地质条件相对较差,页岩气资源勘探潜力较弱;吴三段页岩气地质条件较好,含气性和有机质丰度优于下志留统龙马溪组,显示良好的页岩气勘探潜力。
The Upper Permian Wujiaping Formation in Sichuan Basin exhibits varying sedimentary facies laterally,and there develops a set of marine black shale in the northern Basin.Taking Well Fengtan 1 in northeastern Sichuan Basin as an example,the geological conditions for shale gas were studied by petrological,geochemical,scanning electron microscopy,low-temperature nitrogen adsorption and methane adsorp-tion methods.The results are as follows:(i)Two sets of black shale are developed in the Formation in the study area.One is in the second mem-ber of Wujiaping Formation(Wu 2 Member),consisting of grayish black to black clay shales of shore-side tidal flat facies,with low brittleness index and weak fracturability.The other is in the third member(Wu 3 Member),consisting of black siliceous and calcareous shales of deepwater shelf facies,with high brittleness index and strong fracturability.(ii)The Wu 2 Member shales have the average TOC of 1.41%,of which the black shale is relatively thin,with TOC>2%and Type III organic matters.The Wu 3 Member shales have the average TOC of 3.52%,of which the black shale is 26 m in thick,with TOC>2%and Type II1–II2 organic matters.Both sets are in the over-mature stage.(iii)The Wu 2 Member shales have the reservoir spaces mainly consisting of intergranular pores in clay minerals and microfractures,with relatively underdeveloped or-ganic pores.The reservoir pores are dominated by mesopores,followed by micropores,with a volume of 0.0066 cm3/g and a gas content of 1.5190 cm3/g.The Wu 3 Member shales have the reservoir spaces mainly consisting of organic pores,which are dominated by micropores,followed by mesopores,with an average volume of 0.0141 cm3/g and an average gas content of 2.3070 cm3/g.The pore structure and gas content are controlled significantly by the organic matter abundance,but not obviously by the mineral composition.(iv)The Wu 2 Member shales demon-strate relatively poor geological conditions and weak exploration potential.In contrast,the Wu 3 Member shales have favorable conditions and also good gas potential,with superior gas content and organic matter abundance to the Lower Silurian Longmaxi Formation.
作者
明盈
孙豪飞
叶玥豪
王嘉先
宋金民
王宇峰
邱玉超
陈伟
MING Ying;SUN Haofei;YE Yuehao;WANG Jiaxian;SONG Jinmin;WANG Yufeng;QIU Yuchao;CHEN Wei(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China)
出处
《天然气勘探与开发》
2023年第4期133-147,共15页
Natural Gas Exploration and Development
基金
国家自然科学基金重点项目“青藏高原东缘若尔盖古高原形成与破坏过程及其动力学机制”(编号:42230310)
国家自然科学基金面上项目“川西地区深层雷口坡组微生物岩及其储层形成机理研究”(编号:41872150)。
关键词
川东北地区
晚二叠世
黑色页岩
页岩气地质条件
勘探潜力
Northeastern Sichuan Basin
Lower Permian
Black shale
Geological condition for shale gas
Exploration potential
