摘要
基于岩石学、地球化学、流体包裹体及同位素定年等研究,就热液对四川盆地西南部中二叠统碳酸盐岩储集层幕式改造进行分析。四川盆地西南部中二叠统栖霞组—茅口组白云岩缝洞中充填多期中—粗晶鞍状白云石及其他热液伴生矿物,主要属印支期构造挤压及推覆作用下规模性高温、深部富镁卤水沿基底断裂/伴生裂缝等渗滤通道对早期灰岩/白云岩幕式改造的结果。富镁热液作用时间主要为中—晚三叠世,其次为燕山运动中晚期及喜马拉雅期,热液改造导致了硅质及方解石充填。热液白云石化作用受断层、热液性质、流动路径及围岩岩性等因素复合控制,作用效果以物性“平均化”为主,热液对早期厚层块状颗粒灰岩/白云岩以热液白云石化/热液重结晶作用、破碎角砾化及缝洞充填等改造作用为主;对早期薄—中层泥粒灰岩以压裂、顺层白云石化、溶蚀及伴生矿物充填等产生的溶蚀-充填复合改造为主。热液作用下的破裂缝及溶蚀孔/洞为主要储集空间类型,溶蚀孔洞与网状裂缝的有效连通可形成优质白云岩储集层;典型热液白云岩储集层发育于断裂附近1 km范围内,厚30~60 m,部分孔/洞-缝连通体系发育的热液白云岩储集层具备勘探潜力。
To analyze the episodic alteration of Middle Permian carbonate reservoirs by complex hydrothermal fluid in southwestern Sichuan Basin,petrology,geochemistry,fluid inclusion and U-Pb dating researches are conducted.The fractures and vugs of Middle Permian Qixia–Maokou formations are filled with multi-stage medium-coarse saddle dolomites and associated hydrothermal minerals,which indicates that the early limestone/dolomite episodic alteration was caused by the large-scale,high-temperature,deep magnesium-rich brine along flowing channels such as basement faults or associated fractures under the tectonic compression and napping during the Indosinian.The time of magnesium-rich hydrothermal activity was from the Middle Triassic to the Late Triassic.The siliceous and calcite fillings were triggered by hydrothermal alteration in the Middle and Late Yanshanian Movement and Himalayan Movement.Hydrothermal dolomitization is controlled by fault,hydrothermal property,flowing channel and surrounding rock lithology,which occur as equilibrium effect of porosity and permeability.The thick to massive grainstone/dolomites were mainly altered by filling effects such as hydrothermal dolomitization/recrystallization,brecciation and fracture-vugs filling.Early thin–medium packstones were mainly altered by dissolution and infilling of fracturing,bedding dolomitization,dissolution and associated mineral fillings.The dissolved vugs and fractures are the main reservoir space under hydrothermal conditions,and the connection of dissolved vugs and network fractures is favorable for forming high-quality dolomite reservoir.Hydrothermal dolomite reservoirs are developed within a range of 1 km near faults,with a thickness of 30–60 m.Hydrothermal dolomite reservoirs with local connected pore/vugs and fractures have exploration potential.
作者
冯明友
尚俊鑫
沈安江
文龙
王兴志
徐亮
梁峰
刘小洪
FENG Mingyou;SHANG Junxin;SHEN Anjiang;WEN Long;WANG Xingzhi;XU Liang;LIANG Feng;LIU Xiaohong(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;PetroChina Hangzhou Institute of Petroleum Geology,Hangzhou 310023,China;Research Institute of Exploration and Development,PetroChina Southwest Oil&Gas filed Company,Chengdu 610041,China)
出处
《石油勘探与开发》
EI
CSCD
北大核心
2024年第1期74-87,共14页
Petroleum Exploration and Development
基金
国家科技重大专项(2016ZX05007004-001)
中国石油碳酸盐岩重点实验室创新基金项目(RIPED-HZDZY-2019-JS-695)。
关键词
四川盆地
二叠系
中二叠统栖霞组
中二叠统茅口组
热液流体
热液溶蚀
白云岩
Sichuan Basin
Permian
Middle Permian Qixia Formation
Middle Permian Maokou Formation
hydrothermal fluid
hydrothermal dissolution
dolomite
