摘要
滇黔北地区上奥陶统五峰组—下志留统龙马溪组海相页岩具有较好的页岩气资源前景,但目前对于其复杂地质条件下的页岩气成藏富集规律仍不明确。为此,基于最新的钻井资料,结合野外露头剖面观察和样品测试结果,对该区五峰组—龙马溪组的沉积环境,优质页岩的分布与埋深、有机地球化学指标、储集性参数、含气性等页岩气富集条件进行了系统分析,预测了优质页岩有利区带并评价其勘探潜力。结果表明:(1)该区五峰组—龙马溪组为浅水陆棚—深水陆棚沉积,沉积环境控制了优质页岩的厚度与分布,地史沉积格局和后期构造运动改造控制了底界埋深——底界埋深介于0~4 000 m,优质页岩沉积厚度介于0~60 m;(2)该区优质页岩有机碳含量高(1.0%~4.0%),热演化程度高(过成熟),有机质类型稳定(腐泥型—偏腐泥混合型),生烃强度高(1.0×10~8~4.0×10~8m^3/km^2),生烃潜力较大;(3)优质页岩脆性矿物含量较高,破裂潜力较好,储层储集空间类型多、微裂缝发育;(4)区内局部保存条件较好,具备页岩气成藏的良好地质条件。结论认为:盐津西、筠连南、威信—叙永—古蔺、习水东等4个区域五峰组—龙马溪组页岩气成藏条件优越,具备良好的页岩气勘探潜力,为该区最有利的页岩气勘探区带。
Marine shale of Upper Ordovician Wufeng–Lower Silurian Longmaxi Fms in the northern Yunnan–Guizhou provinces of China has a good prospect of shale gas resources. At present, however, the enrichment laws of shale gas accumulation under complex geological conditions are not clear. In this paper, the shale gas enrichment conditions （e.g. the depositional environment of Wufeng–Longmaxi Fms, distribution and depth of quality shale, organic geochemical indicators, reservoir parameters and gas bearing property） were analyzed systematically based on the latest drilling data, combined with field outcrop profile observation and sample test results. Then the favorable zones of quality shale were predicted and their exploration potential was evaluated. And the following research results were obtained. First, the Wufeng–Longmaxi shale gas reservoirs in this area are deposited in an environment of shallow–deep water shelf, and the thickness and distribution of quality shale are controlled by the depositional environment. The burial depth of bottom boundary is dominated by a historical depositional pattern and the later tectonic movement reworking and it is in the range of 0–4 000 m. And the depositional thickness of quality shale is between 0 and 60 m. Second, the quality shale in this area is characterized by high TOC content （1.0–4.0%）, high thermal evolution degrees （over-mature）, stable types of organic matters （TypeⅠ–Ⅱ1）, high hydrocarbon generating intensity （1.0×10^8–4.0×10^8 m^3/km^2） and a great hydrocarbon generating potential. Third, the quality shale has a better fracturing potential due to its higher content of brittle mineral, and there are various types of reservoir space with developed micro fractures. And fourth, the preservation condition in this area is locally good and it is geologically favorable for shale gas accumulation. It is concluded that western Yanjin, southern Junlian, Weixin–Xuyong–Gulin and eastern Xishui are the most favorable shale gas exploration zones in the northern Yunnan–Guizhou provinces of China, and they are superior in the shale gas accumulation of Wufeng–Longmaxi Fms, presenting a great potential of shale gas exploration.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2017年第12期26-34,共9页
Natural Gas Industry
基金
国家科技重大专项"页岩气勘查评价技术试验与应用推广"(编号:2016ZX05034-004)
中国地质调查局油气基础性公益性地质调查二级项目"四川盆地下古生界海相页岩气基础地质调查"(编号:DD20160176)
关键词
滇黔北地区
晚奥陶世—早志留世
优质页岩
有机地球化学指标
富集条件
有利区预测
勘探潜力
Dianqianbei （Northern Yunnan-Guizhou） provinces
Late Ordovician-Early Silurian
Quality shale
Organic geochemical in- dicator
Enrichment conditions
Favorable zone prediction
Exploration potential
