皖南地区下寒武统页岩气成藏地质条件

doi:10.11743/ogg20140517

摘要/Abstract

摘要：

以野外剖面观测和室内薄片及扫描电镜分析为基础，结合地质与钻井等资料，提出皖南地区下寒武统沉积相的具体划分方案。认为盆地相的深水还原环境是形成页岩气藏的最佳相带，而碳酸盐缓坡不利于页岩气勘探；对储层贡献最大的储集空间类型为裂缝，其次为次生溶蚀微孔，而晶间孔相对不发育，对储层的贡献则十分有限。从富含有机质页岩的空间展布、地化特征、保存条件等方面出发，采用页岩气目标优选评价综合分析方法，对皖南地区下寒武统页岩气成藏条件进行了研究，着重定量评价了页岩厚度、有机碳含量、镜质体反射率、脆性矿物含量等指标。皖南地区下寒武统页岩平均厚度大于50 m，石台县-南陵县一带达页岩厚度最大值为200～600 m；有机碳含量较高，平均值达2.37%；镜质体反射率平均值大于2%，页岩气藏处于干酪根裂解气的成熟-高熟阶段；脆性矿物含量较高，平均值为46.89%，有利于压裂形成网络裂缝。通过与美国主要页岩气藏的地化参数进行对比分析，认为皖南地区下寒武统页岩具备非常优越的页岩气成藏条件，可选为我国非常规能源首选的有利区之一。

关键词: 沉积相, 热演化, 构造运动, 页岩气, 皖南地区

Abstract:

Based on outcrop investigation,thin-section observation and SEM analysis,a detail division scheme of sedimentary facies was proposed for the Lower Cambrian in southern Anhui combining with geology and wellbore data.The most favorable facie belt for shale gas accumulation is deep-water deduction environment in the basin,while the carbonate ramp is unfavorable for shale gas exploration.Fractures make the greatest contribution to the storage of shale gas reservoir,followed by the secondary dissolution micro-pores.In contrast,intercrystalline pores contribute the least due to their relatively poor development.This paper comprehensively studied the geological characteristics of the Lower Cambrian shale gas play in southern Anhui in such aspects as spatial distribution of organic-rich shale,geochemical behaviors and preservation conditions.The study was focused on quantitative evaluation of shale thickness,TOC content,R_o and brittleness.The Lower Cambrian shale in southern Anhui is more than 50 meters on average,with the maximum thickness in the range from 200 to 600 meters occurring in Shitai and Nanling counties.The shale gas play has an average TOC content of 2.37%.The average Ro is more than 2%,indicating that the shale is at mature-high mature stage.The average brittle mineral content is 46.89%,being favorable for the creation of fracture networks through hydraulic fracturing.Based on comparison with the geochemical parameters of the main large shale gas plays in America,it is indicated that the Lower Cambrian shale in southern Anhui has favorable accumulation conditions for shale gas,thus can be selected as one of the play fairways in China.

Key words: sedimentary facies, thermal evolution, tectonic movement, shale gas, southern Anhui, province

中图分类号:

TE122.3

卢炳雄,郑荣才,文华国,等. 皖南地区下寒武统页岩气成藏地质条件[J]. 石油与天然气地质, 2014, 35(5): 712-719. doi: 10.11743/ogg20140517 Lu Bingxiong,Zheng Rongcai,Wen Huaguo,et al. Accumulation conditions of the Lower Cambrian shale gas in southern Anhui province[J]. Oil & Gas Geology, 2014, 35(5): 712-719. doi: 10.11743/ogg20140517

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