黔东北地区牛蹄塘组页岩气勘探前景分析

黔东北地区页岩气资源丰富，特别是牛蹄塘组勘探潜力巨大。本文在先期勘探失利井(CY1、HY1、FS1)分析基础之上，结合大量岩石露头、岩心分析测试数据，对黔东北地区页岩气的地质特征进行了系统研究，进一步落实了该地区资源潜力。研究认为：黔东北页岩气区下寒武统牛蹄塘组干酪根有机显微组分主要以腐泥无定型和腐殖无定型为主，有机质类型主要为Ⅰ型和Ⅱ1型；页岩层段有机质含量高，平均3.52%；镜质体反射率平均3.58%，为成熟晚期阶段；储层具有低孔超低渗、高比表面积等特征；页岩层脆性矿物含量平均64.2%，黏土矿物平均含量19.6%，牛蹄塘组硅质含量高，脆性较大，易于储层改造；黔东北地区页岩气可采资源量达0.12×1012 m3。可优选岑巩、沿河、秀山、德江、凯里等有利地区进行下一步的勘探和评价工作。

Analyses on the shale gas exploration prospect of the Niutitang Formation in northeastern Guizhou Area

The shale gas resources are rich in the northeastern Guizhou area, especially in the Niutitang Formation. Based on the former failed drilling wells, combined with abundant analytical data of outcrops and cores, this study systematically investigated the geological characters of the Niutitang Formation in the northeastern Guizhou area and further implemented the resource potential in the study area. The following understandings are obtained. The kerogen types of organic matter are mainly of typeⅠand typeⅡ1, of the Niutitang Formation in the northeastern Guizhou area. The TOC content is high, with an average value of 3.52%. The average value of Ro is 3.58%, which reflects that the source rock has entered high maturation stage. The reservoirs are characterized by low porosity ultralow permeability and high specific surface area. The results show that the brittle and clay minerals are averaged at 64.2% and 19.6%, respectively. The high siliceous contents and great brittleness is favorable for reservoir alteration. The recoverable resource of shale gas is estimated at 0.12 billion cubic meters. Areas including Cen gong, Yanhe, Xiushan, Dejiang, Kaili, etc. can be selected for further exploration and evaluation in the northeastern Guizhou area.