沅麻盆地下寒武统页岩气油气地质特征  

Geological Characteristics of Lower Cambrian Shale-gas Reservoir,Yuanma Area

作　　者：刘苗苗[1] 

机构地区：[1]中国石化勘探分公司,四川成都610000

出　　处：《天然气技术与经济》2015年第3期18-21,77,共4页Natural Gas Technology and Economy

摘　　要：根据野外露头观察,从富含有机质页岩空间展布、地化特征、岩石矿物学、孔渗性特征等方面,采用页岩气目标优选评价综合分析方法,对沅麻地区下寒武统牛蹄塘组页岩油气地质特征进行了综合研究,着重定量评价了有机碳含量、镜质体反射率、孔隙度、脆性矿物含量、岩石矿物成分等评价指标。研究结果表明：该套页岩在研究区内广泛分布,沉积厚度大,值为50～120 m,有机质丰度高的页岩主要集中于牛蹄塘组下部的碳质页岩中,热演化程度高,达到过成熟阶段（2.5%～3.0%）,具有形成页岩气藏资源的良好潜力;黑色页岩脆性矿物丰富、含量大,微孔缝发育,孔隙度高（1.98%～12.08%）。反映牛蹄塘组优质的储集条件,综合研究评价出草堂凹陷、辰溪凹陷两个有利油气分布区。The shale in the Lower Cambrian Niutitang Formation, Yuanma area, is rich in organic matter. Based on outcrop observation and through some optimization and evaluation approaches for shale-gas targets, many hydrocarbon geological characteristics of the organic-rich shale are studied in terms of many aspects, such as shale distribution, geochemical, petrological, and porosity-permeability features. In addition, a number of indexes containing organic carbon content, vitrinite reflectance(RO), porosity, content of brittle minerals, and mineral composition are evaluated. Results show that(1)the shale developed broadly in the study area is characterized by large depositional thickness varying from 50 m to 120m;(2)the carbonaceous shale in the lower Niutitang Formation which has much organic matter with high abundance is featured by high thermal evolution degree attaining an overmature stage(2.5 %~3.0 %), all proving that the carbonaceous shale has a better potential to form shale- gas resources;(3)in the black shale,there are abundant brittle minerals with developed microfractures and high porosity(1.98 %~12.08 %);(4)the Niutitang Formation has high-quality reservoir conditions; and(5)there are two favorable gas distribution belts of both Caotang and Chenxi depressions.

关 键 词：富有机质页岩 页岩气 牛蹄塘组 沅麻地区 

分 类 号：P618.13[天文地球—矿床学]