湖南永顺区块牛蹄塘组页岩气勘探前景及选区评价

Exploration potential and favorable paly identification of Niutitang formation shale gas of Yongshun block in Hunan province

永顺区块位于中上扬子地台牛蹄塘组页岩气富集区,整体勘探程度较低,页岩气勘探前景不明。利用露头、岩心、测试和地震等资料,分析研究区牛蹄塘组页岩气勘探前景,以页岩气富集理论为指导,结合地球化学分析技术、地质评价—地球物理联合预测技术,评价有利勘探区块。结果表明:永顺区块牛蹄塘组具有优越的烃源供给条件,厚度大,分布广,燕山期是其主要的聚集及成藏期;页岩储层低孔低渗特征明显,储集类型多样,脆性矿物丰富,有利于页岩气储集及压裂改造;研究区构造样式相对简单,断裂、盖层发育分区性明显,关键构造事件控制源盖动态匹配。残留向斜斜坡是研究区有利的勘探目标,Ⅰ类有利区面积为102.1km^2,Ⅱ类有利区面积为88.2km^2。

Yongshun shale gas block is located in the shale gas abundant play of the Niutitang formation in middle-upper Yangtze platform,where the whole exploration degree is in a low level and the shale gas exploration potential is also unknown.For further analysis of the study area Niutitang shale gas exploration prospect,making use of the outcrop,cores,test and seismic data,guiding with the shale gas accumulation theory,combining with the geological-geochemical-geophysical joint research method,preferably evaluating favorable exploration blocks.The research shows that:First,the Niutitang formation in Yongshun block has superior source supply condition,with horizontally pervasive distribution and vertically thickness,which Yanshan period is the main accumulation period of the Niutitang formation.Second,the reservoirs are the obvious characteristics of low porosity and low permeability,but with diverse reservoir space types and rich brittle mineral content,which is conducive to shale gas reservoir and latter fracturing.Third,the structural styles are relatively simple in the study area,with fault and cap rock development obviously zoning,and the key tectonic events control the dynamics match relationship of source-seal.Comprehensive evaluation by various control factors suggest that residual syncline is beneficial exploration targets in the study area,with evaluating and optimizing the Ⅰ 'favorable paly' area102.1km^2,Ⅱ 'favorable pal' area 88.2km^2.