康滇隆起东缘上三叠统页岩气有利区优选

Optimum Selection of Shale Gas Favorable Area of Upper Triassic in the Eastern Margin of Kangdian Uplift

何磊 牟必鑫 杨平 陈杨 刘治成

HELei MUBixin YANGPing CHENYang LIUZhicheng

中国地质调查局成都地质调查中心, 四川 成都 610081 四川省煤田地质工程勘察设计研究院, 四川 成都 610072 页岩气评价与开采四川省重点实验室, 四川 成都 610072 四川省国土科学技术研究院(四川省卫星应用技术中心), 四川 成都 610045

Chengdu Center, China Geological Survey, Chengdu, Sichuan 610081, China Sichuan Institute of Coal Field Geological Engineering Exploration and Designing, Chengdu, Sichuan 610072, China Key Laboratory of Shale Gas Evaluation and Exploitation of Sichuan Province, Chengdu, Sichuan 610072, China Sichuan Institute of Land Science and Technology (Sichuan Satellite Application Technology Center), Chengdu, Sichuan 610045, China

基于康滇隆起东缘西昌盆地上三叠统大量露头剖面、钻井和测试资料综合分析，评价了西昌盆地米市拗陷及周缘白果湾组富有机质页岩的主要指标，进行页岩气选区评价。西昌盆地白果湾组第一至第四段均发育湖相或沼泽相富有机质页岩，其中，果湾组二段下部厚度一般为40~89 m，果湾组三段下部厚度最大可达251 m。白果湾组页岩平均有机碳为1.0%~1.6%，干酪根有机碳同位素为-26.2‰~-23.2‰，有机质类型为II-III型，米市拗陷东部为1.1%~3.0%，演化程度适中。通过对比不同地区陆相页岩的各项指标，发现有机质含量、热演化程度是研究区页岩气形成的重要因素。采用成因法估算白果组页岩含气量为1.0~1.5 m/t，利用多因素叠合法分段优选了页岩气有利区，分区评价了页岩气资源量，西昌盆地白果湾组有利区页岩气资源量共7 106×10 m，其中，白果湾组三段最有利，资源量为3 094×10 m。米市拗陷东部的特尔果和七里坝等有利区有望实现新区新层系的页岩气发现。

Based on the analysis of outcrop profile, drilling and testing data of Xichang Basin in the eastern margin of Kangdian Uplift, the main indexes of organic-rich shale in Baiguawan Formation were evaluated and the shale gas selection was evaluated. The results show that: 1) Organic-rich shale of lacutrine or marsh facies is developed in the first to fourth Member of Ginguowan Formation in Xichang Basin, the thickness of the lower part of the second Member is generally 40~89 m, and the thickness of the lower part of the third member is up to 251 m. 2) Average organic carbon of Baiguowan Formation shale is 1.0%~1.6%, the organic carbon isotope of kerogen is -26.2‰~-23.2‰, and the organic matter type is II-III type. The in the eastern Mishi Depression is 1.1%~3.0%, indicating moderate evolution degree. 3) The content of organic matter and the degree of thermal evolution are important factors for the formation of shale gas in the study area. 4) Shale gas content of Baiguowan Formation was estimated to be 1.0~1.5 m/t with the genetic method. The favorable shale gas areas were selected with the multi-factor overlapping method, and the shale gas resources were evaluated by regions. The total shale gas resources of the favorable shale gas area of Baiguowan Formation in Xichang Basin is 7 106×10 m, among which the resources of the third Member of Baiguowan Formation is 3 094×10 m. Shale gas is expected to be discovered in the new zone and new strata in favorable areas such as Terguo and Qiliba in the east of Mishi Depression.

10.11885/j.issn.1674-5086.2021.10.14.01