莺歌海盆地东方区黄流组高温超压砂岩储集层发育机理

The Mechanism of High-Temperature and Overpressure Sandstone Reservoir Development of Huangliu Formation in Dongfang Area of Yinggehai Basin

莺歌海盆地东方区黄流组砂岩具有明显的高温超压环境成岩特征。通过岩石薄片、阴极发光、扫描电镜、包裹体测温和X衍射等研究手段,对黄流组砂岩在高温超压下的成岩特征进行了研究,并分析了成岩作用对储集性能的影响。高温超压下黄流组砂岩具有弱压实、强溶蚀的特点,并结晶了菱铁矿、重晶石和金红石等热液成因的自生矿物。高温超压环境下不仅原生孔隙被大量保存,而且高温热流体对长石类矿物的溶蚀也有利于大量次生孔隙的形成。菱铁矿、铁方解石和铁白云石的胶结和自生高岭石的充填使储集层孔隙度降低,而蒙脱石向伊利石的快速转化是储集层渗透率急剧下降的主要因素。研究结果表明,高温超压不仅对于砂岩储集层原生孔隙起到保护作用,也导致了不稳定矿物的大量溶蚀。高温超压下储集层发育机理的研究对于砂岩中"甜点"储集层的预测具有重要意义。

The sandstone of Huangliu formation in Dongfang area of Yinggehai basin is characterized by obvious high-temperature and overpressure diagenetic environment.By means of thin section,cathodeluminescence,SEM,enclosure,X-ray,etc,this paper studied the diagenetic characteristic of Huangliu sand under high-temperature and overpressure and its effect on the reservoir quality.This sandstone with poor compaction and strong corrosion has crystallized with such authigenic minerals of hydrothermal origin as siderite,barite and rutile,etc.Under the high-temperature and overpressure,the primary porosity was not only preserved mostly,but also favorable to forming a great amount of secondary pores for dissolution of the high temperature hydrothermal fluid on feldspathic mineral.The cementing of siderite,ferrocalcite and ferrodolomite and the filling of authigenic kaolinite were resulted in lower porosity of the reservoir,while the rapid smectite-illite conversion could be the main reason for quick decline of the reservoir permeability.The studied result shows that the hightemperature and overpressure could not only preserve the primary porosity in this reservoir,but also result in a great amount of corrosion of unstable minerals.Conducting research of the reservoir development mechanism under high-temperature and overpressure is of great significance for prediction of ＂dessert＂ in the sandstone reservoir.