利用临兴地区下石盒子组沉积砂体的重矿物、阴极发光、微量元素等资料,运用统计、计算等方法,确定出研究区下石盒子组的储层碎屑颗粒来源,并结合盆地周缘喷发出的火山物质探讨物源对储层的影响。研究结果表明,研究区下石盒子组砂岩中碎屑颗粒物源主要来自盆地北部阴山山脉,其母岩岩性为片麻岩相、变粒岩相、麻粒岩相及混合花岗岩、花岗闪长岩、火山岩等,主体由前寒武纪变质岩构成,填隙物物源主要为盆地周缘火山喷发形成的凝灰质。在物源控制下,下石盒子组砂岩骨架颗粒组分具有高含量岩屑特点,但由于水流的分异作用,千枚岩、泥板岩等塑性岩屑常存在于中砂级以下的砂岩中,在压实作用下破坏储层储集性能,粒度较粗的砂岩则因具有高含量刚性颗粒特点仍然可以形成优质储层;而同沉积的火山物质因不受水流分异作用的影响而广泛存在于各粒级砂岩中,因其具有塑性特征,在压实作用下加剧了储层致密化。火山物质为绿泥石环边的形成提供了物质基础,抑制石英加大边,在接受溶蚀后形成良好储层。由于物源区母岩长石矿物含量较低,粒内以及粒间孔隙多数由火山物质的溶蚀所提供。因此,火山物质相对于母岩区碎屑颗粒对储层的影响更大,是导致储层致密化以及非均质性的重要因素。
Based on the data of heavy mineral,cathode luminescence,microelement,and combined with the method of statistics and calculation,we determined the provenance of clastic particles of Lower Shihezi For-mation in study area,and combine with volcanic material around the basin to discuss the influence of prove-nance on reservoir.Research shows that the parent rock lithology of clastic particles is gneiss phase,granu-lite,migmatitic granite,granodiorite,igneous rock and so on,which come from Yinshan mountain ranges and mainly consisted of metamorphic rock of Precambrian,interstitial fillings mainly come from tuffaceous particle which is from volcanic eruption.Under the provenance controlling,clastic particles have the charac-teristic with high debris composition in Lower Shihezi Formation,however,because of the function of water differentiation,the plastic debris such as phyllite rock,argillite exist in sandstone with medium particle size or lower than it,and destroy reservoir property with compaction.On the other hand,the coarse sand has the characteristic with high rigidity particle and could constitute good reservoir.Volcanic material of synsedi-mentary exist in sandstone with different grain sizes because it is not influenced by water,which has the characteristic of plastic to speed up to process of reservoir getting tighter.Volcanic matter provides the ma-terial to form rim chlorite which could inhibit quartz overgrowth and form good reservoir after corrosion. As parent rock has little feldspar,the maj ority of interparticle and intragranular dissolved pore are formed from the corrosion of volcanic material.In one word,volcanic matter has more influences than clastic parti-cles in reservoir,which is the important factor that cause densification and anisotropy in reservoir.