盐源—宁蒗地区早泥盆世古地理特征及油气潜力分析

A study on paleogeography of the Early Devonian and potential of hydrocarbon resources in Yanyuan-Ninglang area, southwest of China

关键词:  盐源—宁蒗地区  早泥盆世  古地理  黑色页岩  油气

Key words:  Yanyuan-Ninglang region  Early Devonian  Paleogeography  Black shale  Oil and gas

摘要:

为了探索康滇地轴以西地质条件复杂地区的油气资源潜力，通过面积性地质调查工作与钻孔资料、分析测试资料结合，对盐源—宁蒗地区下泥盆统黑色页岩开展综合研究。研究表明：盐源—宁蒗地区早泥盆世古地理主要受康滇古陆及古特提斯构造域的构造活动控制，靠近金-箐断裂地区发育滨岸-潮坪相，古隆起围限区出现局限海湾相，远离隆起的西北部地区发育台地、陆棚、盆地相；大瓜坪组（早泥盆世晚期）发育黑色页岩（局部地区发育硅质泥岩），在羊排喜—岩口一带分布较为稳定、厚度大（20～100m），普遍含钙质，有机碳含量较高，具较高的脆性矿物含量，热演化程度适中，是重要的烃源岩和页岩气富集有利层位；黑色页岩主要发育在局限海湾环境中，羊排喜—岩口—茅坪子一线是盐源—宁蒗地区黑色页岩富集区。

Abstract:

In order to explore the potential of oil and gas resources in areas west of the Kangdian Earth'axis, a comprehensive study of the Early Devonian black shale in Yanyuan-Ninglang region is carried out by combining the regional geological survey work with drilling and testing data. The results indicates that:(1) The early Devonian paleogeography of Yanyuan-Ninglang area is mainly controlled by the Kangdian Paleo-land and the activities of the Paleo-Tethys tectonic domain. Littoral tidal flat facies developed in the area close to the Jinhe-Qinghe fault, restricted bay facies appeared in the local area surrounded by the Paleo-uplift and platform, while continental shelf and basin facies developed in the northwest area far from the uplift.(2)In the late early Devonian,the Daguaping Formation developed the black shale, which is relatively stable in distribution and thick (20m to 100m) in the Yangpaixi-Yankou area and generally contains calcium, high contents of organic carbon and brittle minerals and with a moderate thermal evolution. It is an important source rock and favorable shale gas horizon.(3)Black shale develops in a restricted bay environment, and places such as Yangpaixi, Yankou, Maopingzi, are the most favorable areas in the Yanyuan-Ninglang region.