摘要
四川盆地上三叠统须家河组陆相富有机质页岩较为发育,页岩连续厚度较大,含气性好,有望开辟四川盆地页岩气新区新层系。然而,复杂的人文干扰(城镇密集、人口众多)和较大的埋藏深度(2000~3000m)挑战了页岩气地球物理勘探的精度,这在很大程度上制约了川西南沐川地区三叠系须家河组页岩气的进一步勘探。本文在分析前人研究资料基础上,优选了川西南沐川地区须家河组作为新区新层系的探测目标,根据研究区地质情况,构建理论电性模型,通过正演模拟和“已知”钻孔标定方法试验,确定了宽频大地电磁法的适用性和有效性。进而在重点页岩气远景区部署一条宽频大地电磁剖面,通过数据处理分析,结合地质资料获得了研究区深部电性结构,认为研究区一带地层连续、完整,断裂不发育,具有稳定的地质结构,其中上三叠统须家河组发育较大厚度的富有机质页岩,可作为本区页岩气勘探的新区新层系,具有良好的页岩气、致密气资源前景。同时,证实了在3000m以浅页岩气探测方法中,宽频大地电磁法(BMT)可以有效地识别富有机质页岩规模和空间展布特征,是一种快速、经济、无损有效的页岩气探测方法,可以为页岩气勘探提供先导依据,同时也为同类地质情况页岩气探测提供应用示范。
The Upper Triassic transitional shale of the Xujiahe Formation is characterized by organic-rich materials and large continuous thickness.It is expected to become a new target layer for shale gas exploration in the Sichuan Basin.However,the disturbances of dense cities and towns,large population,and the large burial depth of 2000 m to 3000 m challenges the traditional geophysical exploration method of shale gas in the region.Based on the analysis of existing data,this paper takes the Xujiahe Formation in the Muchuan area of southwest Sichuan as the research object.Combined with geological conditions,a theoretical electrical model of shale gas detection based on BMT method was established.Its applicability and validity were verified by forwarding simulation and known shale gas boreholes.By deploied BMT profiles in key shale gas exploration areas to explore the deep electrical structure of the study area,and processing and analyzing the obtained BMT data in combination with geological data.We found that the Xujiahe Formation in the study area is continuous and complete,with poorly developed faults.The organic-rich shale of the Upper Triassic Xujiahe Formation has a large thickness and displays a very good shale gas potential,which may become a new layer for shale gas exploration in this area.It is concluded that the BMT method can effectively identify the scale and spatial distribution of organic-rich shales,which is a quick,economic,and effective geophysical exploration method for shale gas detection at a depth of 3000 m underground.
作者
杨剑
王桥
刘伟
夏时斌
张伟
廖国忠
李华
高慧
YANG Jian;WANG Qiao;LIU Wei;XIA Shibin;ZHANG Wei;LIAO Guozhong;LI Hua;GAO Hui(Chengdu Center,China Geological Survey,Chengdu 610081,China)
出处
《沉积与特提斯地质》
CAS
CSCD
北大核心
2022年第3期444-454,共11页
Sedimentary Geology and Tethyan Geology
基金
中国地质调查局项目(DD20190033、DD20190080)
国家自然科学基金(41604118)联合资助。
