子长北部地区盒_8段储层成岩作用研究

Reseach on the sandstone diagenesis of the 8th member of Shihezi Formation in north of Zichang area

应用了普通薄片、铸体薄片、扫描电镜等多种测试手段对研究区盒8段砂岩的成岩作用及其对储层的影响等做了分析说明。认为:研究区储层主要为岩屑石英砂岩,几乎不含或者含极少量的长石;压实作用是造成砂岩储层孔隙丧失的主要原因之一,而胶结作用加剧了原生孔隙的进一步减小,尤其是碳酸盐胶结,其次是石英加大边和高岭石;但绿泥石膜胶结物的存在抑制了压实作用的进一步进行,有利于粒间孔的保存;而成岩后期的溶蚀作用,改善了储层物性。储层处于晚成岩A-B期阶段,溶蚀型次生孔隙成为这一阶段主要的孔隙类型,其发育带往往是有利储层发育区。

Multiple analysis methods including general slice and casting slice scan electron microscope,etc,were adopted to study the diagenesis of the 8th member of Shihezi Formation sandstone of the study area and its effects on physical properties.The result shows that Lithic quartz sandstone is the main sandstone type,with less or low composition feldspar;compaction is one of the main causes for porosity losses,and the primary porosity loses further under cementation which is also the main cause of this compact sandstone,especially,carbonate,secondly,quartz increasing margin and kaolinite,but cementation of chlorite film can restrain compaction and is beneficial to preserve primary porosity.Physical properties of sandstone reservoirs can be improved by dissolution,during the later period of diagenesis.Diagenesis reaches A-B period,porosity developed by dissolution is one of the main porosity-type of this period,where it is developed well is the favorable reservoirs area.