川东南南川地区茅口组一段碳酸盐岩储层特征及富集模式

Reservoir properties and accumulation mode of carbonate rocks in Mao1 Member of Nanchuan Area in southeast Sichuan

四川盆地二叠系茅口组海相碳酸盐岩地层是天然气有利勘探层系,勘探潜力大。为进一步明确该区域富集模式,以钻井岩心等资料为基础,利用矿物岩石学、地球化学、普通薄片和氩离子抛光扫描电镜等实验分析技术,开展茅一段储层特征研究。主要研究成果如下1)川东南南川地区茅一段为深水外缓坡相,岩性以纯灰岩、泥质灰岩/碳质泥岩和云质灰岩/灰质白云岩为主,发育眼球状构造;2)川东南南川地区茅一段储集空间以裂缝及孔隙型为主,各类有机孔及无机孔通过裂缝(页理、层理和粒缘缝)沟通,形成相较于泥质灰岩储集空间更好、渗流能力更强的基质孔隙储集空间;3)构造运动产生的大尺度裂缝与基质孔隙储层叠合区具有更好的储集能力及渗流能力,实钻井显示构造高部位叠合区气测明显高于其他部位。该研究成果对茅口组碳酸盐深水外缓坡亚相灰泥灰岩的勘探工作具有指导价值。

In the Sichuan Basin,marine carbonate rocks of Maokou Formation of Permian are favorable gas exploration zones.In order to further clarify the regional enrichment pattern,based on drilling cores and other data,the reservoir characteristics of the first member of Mao1 Member were studied by using experimental analysis techniques such as mineral petrology,geochemistry,ordinary thin section and argon ion polishing scanning electron microscope.The main research results are as follows:1)The sedimentary facies of Mao1 Member is deep water outer gentle slope facies,and the formation lithology is mainly limestone,argillaceous limestone or carbonaceous mudstone and cloud-limestone or calcareous dolomite,eyeball-shaped limestone developed.2)The reservoir space of Mao1 Member in southeastern Sichuan Basin is dominated by fractures and pores.Various organic pores and inorganic pores communicate through fractures(lamellation,bedding and grain boundary fractures)to form a high-quality matrix pore reservoir space with better storage capability and stronger permeability than the argillaceous limestone reservoir space.3)Large scale fractures which generated by tectonic movement,combined with matrix pore reservoir space have better reservoir capacity and seepage capacity,and the actual drilling shows that gas measurement in the composite area in culmination is significantly higher than that in other area.The above knowledge is of guiding value to the exploration of marl limestone of Maokou Formation,which is belong to carbonate deep-water outer gentle slope subfacies.