页岩气区域地质调查和钻探成果表明,滇黔北坳陷属于改造残留型构造坳陷,海相下志留统龙马溪组和下寒武统牛蹄塘组黑色页岩发育,单层厚度达50m以上.评价区页岩的厚度、埋深、TOC、含气性、力学性质、物性和矿物成分等评价参数与北美已商业开发页岩气田的具有一定相似性,具备形成页岩气藏的有利地质条件,是现实的页岩气勘探开发重要目的层系.下古生界海相页岩受晚期构造活动影响强,有机质热演化程度高,通天断层、区域盖层剥蚀、大气淡水冲刷等严重影响其含气性,但页岩的含气性随保存条件变好和TOC丰度增大而明显增加.影响页岩气藏赋存的关键因素是页岩厚度、TOC含量、页岩气储层空间和保存条件.提出该区页岩气有利勘探区带综合评价优选时,需要综合考虑“定性与定量相结合”的六个原则条件,保存条件应成为页岩气地质综合选区的重要因素.优选出彝良-筠连-叙永区域为龙马溪组和牛蹄塘组页岩气目的层叠合的有利勘探区带,赫章-镇雄区域为牛蹄塘组页岩气目的层的有利勘探区带.

Dianqianbei Depression is a reformed residual region. Based on the results of regional geological survey and drills in the gas-bearing shale zones in the northern part of it, it is shown that the excellent marine black shale is more than 50 m thick in net thickness respectively in lower Silurian Longmaxi and lower Cambrian Niutitang Formations. The shale evaluation factors for both formations in this area, including the shale thickness, buried depth, gas content, mineral composition, organic geochemical indices, mechanical and physical properties, etc., are rather similar in correlation with those in the commercial shale gas fields in America. It means that these shale formations are favorable for hydrocarbon accumulation and can be the prospecting targets. Effected by late intense tectonic activities, the lower Paleozoic marine shale would be seriously influenced by some adverse factors such as heavy fracturing, regional cap-rock erosion and atmospheric freshwater leaching but the gas concentration in the shale would increase with increasing TOC content and well-getting preservation. It is suggested that as integrated evaluation and selection of plays for exploration, six "qualitative and quantitative principles" (QQP) should be taken into account. The preservation condition should be the key one of factors. It is proposed that the plays for exploration targets are the Longmaxi and Niutitang gas-bearing shale in Yiliang-Junlian-Xuyong area, and Niutitang gas-bearing shale in Hezhang-Zhenxiong area.