大牛地气田石炭系太原组沉积相类型再分析

Reanalysis of sedimentary facies types of Carboniferous Taiyuan formation in Daniudi gas field

在区域地质背景分析的基础上,对大牛地气田石炭系太原组各类沉积物特征进行分析,结果表明,太原组砂岩具有石英颗粒含量高、分选好的微观特征,宏观分布具有相对平直、宽度较窄、厚度相对较大的条带状展布特点;太原组储层发育纵向交错层理、羽状交错层理、似"单向"水流构造、脉状层理、波状层理、透镜状层理等,为典型的潮汐作用形成;结合储层岩石粒度分析、测井相类型分析,可识别出浅灰-灰白色块状层理石英砂岩相、浅灰色交错层理石英砂岩相、灰色波状层理细、粉砂岩相和深灰色微晶灰岩相等岩石相类型:太原组为潮坪相潮间带沉积,发育潮道、潮沟、潮池、泥坪、泥沼坪等微相,有利储层为潮道及潮沟砂岩。

Based on the analysis of regional geological background, the sedimentary characteristics of Taiyuan formation of Carboniferous system in Daniudi gas field are analyzed. The results indicate the sandstone of Taiyuan formation has the microcosmic characteristics of high quartz grain content and good separation. The macroscopic distribution has the strip spreading point of relatively straight, narrow width and relatively large thickness characteristics. The reservoirs in the Taiyuan formation developed longitudinal cross-bedding,feather-like cross-bedding, ’one-way’ flow structure,vein-like bedding, wavy bedding and lenticular bedding,etc., which were formed by typical tidal action. Combined with the reservoir rock particle size analysis and well logging facies analysis, it can he identified that the shallow grey, grey-white massive bedding quartz sandstone facies, light gray cross-bedding quartz sandstone facies, gray wavy bedding fine, siltstone facies and dark gray microcrystalline limestone facies.According to the analysis of the same type of rock facies,Taiyuan formation is deposited in tidal flat facies intertidal zone, and develops microfacies, such as tidal channel, tidal creek, tidal pool, mud flat and mud swamp.The favorable reservoir is tidal channel and tidal gully sandstone.