黔南代页1井下石炭统打屋坝组页岩气地质条件及勘探前景

Geological conditions and exploration prospect of shale gas in Dawuba Formation of Lower Carboniferous of Daiye-1 well in southern Guizhou Province

近年来发现黔南地区下石炭统打屋坝组发育厚度较大的黑色页岩层,该地层已经成为黔南地区重要的页岩气目标地层。为进一步了解该地层的页岩气参数,评价其页岩气勘探潜力,对代页1井打屋坝组黑色页岩进行观察和取样分析,显示该井打屋坝组黑色页岩钻厚为80 m,总体为一套深水陆棚相沉积;干酪根显微组分以腐泥组、壳质组和镜质组为主,Ⅰ型—Ⅲ型干酪根均有发育,有机碳(TOC)含量主要分布在1.5%~3.3%之间,镜质体反射率(Ro)为2.15%~2.66%;矿物组成以石英、黏土矿物为主,脆性矿物(不含方解石)含量在35%~64%之间;含气量在0.49~4.97 m^3/t之间,平均为2.20 m^3/t。通过露头剖面观察,显示黔南下石炭统打屋坝组黑色页岩厚度均较大,代页1井含气量较高,有机地化、储集物性参数较好,反映打屋坝组具有良好的勘探前景,可进一步加强该地层的基础地质、页岩储层改造和页岩气富集规律研究工作。

Recent studies have shown that the black shale in Dawuba Formation of Lower Carboniferous is widely distributed in southern Guizhou Province. The formation with black shale has become an objective layer of shale gas exploration in this area. In this study,the black shale samples in Dawuba Formation of Daiye-1 well are analyzed to obtain some crucial parameters of shale gas and evaluate exploration potential. The results show that,firstly,the sedimentary environment of Dawuba Formation is mainly deep sea shelf and the thickness of black shale is 80 m; secondly,kerogen maceral is mainly sapropelinite,exinite and vitrinite. The kerogen type of Dawuba Formation is dominated by type Ⅰ to type Ⅲ. The TOC content of black shale in Dawuba Formation is 1. 5%- 3. 3% and the Roranges from 2. 15% to 2. 66%; thirdly,quartz and clay minerals are the dominant minerals in the black shale,and the content of brittle minerals( calcites not contained) ranges from 35% to64%; finally,the shale gas content of field measurement is between 0. 49 m^3/ t and 4. 97m^3/ t with the average value of 2. 20 m^3/ t. Meanwhile,the Dawuba Formation with great thickness has good gas content,organic geochemical index and reservoir potentiality by field investigation and laboratory tests. Furthermore,the black shale of Dawuba formation has good exploration prospects,so it is significant to further investigate the basic geology,shale reservoir exploitation and shale gas regularity.