鄂尔多斯盆地L地区上古生界上石盒子组物源特征及其对储层的控制作用

首先从岩屑分布、重矿物组合、稀土元素等多方面，对L地区石盒子组进行了物源分析。分析结果表明，研究区上古生界碎屑颗粒主要来自盆地北部的中上元古界大青山母岩的变质岩体，晚石盒子期还同时受到盆地东北缘的太古宙内蒙造山带兴蒙物源影响，其母岩主要为混合花岗岩、变质岩及侵入岩体。复合物源的共同控制使上石盒子组形成了富含长石、岩屑且岩浆岩岩屑含量显著增高的砂岩储层。溶蚀作用是控制储层质量的主要机制，优质储层主要受岩屑、长石、火山凝灰质填隙物等易溶矿物分布的影响；另一方面，通过分析各类沉积相标志识别了L地区上石盒子组的主要沉积微相类型及展布特征，确定其主要发育砂泥岩不等厚互层的三角洲前缘沉积，水下分流河道为骨架砂体，储层物性具明显相控规律。总体上，上石盒子组储层受物源及其控制下的沉积相共同影响，其储集性能在上古生界具有相对优势。

Characteristic of provenance and its impact on reservoir quality of Upper Shihezi Formation,L block,Ordos Basin

Based on the data of lithic fragment,heavy mineral，rare earth element,the provenance of clastic particles of Upper Shihezi Formation is analyzed in the study area．The research showed that the clastic particles mainly came from the Yinshan mountain ranges which mostly consisted of metamorphic rock of Precambrian．It was also controlled by the granodiorite，intrusive body of Archaeozoic and Proterozoic,which was from Inner Mongolia orogenic belt．Under the joint influence of the two parent rock origins，clastic particles in Upper Shihezi Formation had the characteristic with high debris composition and more feldspar.The dissolution under the provenance control was the main mechanism to control the reservoir quality，which was influenced by the distribution of soluble minerals such as feldspar，rock debris，volcanic tuff and so on.On the other hand， different kinds of sedimentary facies signs were analyzed，identifying the major microfacies type and its distribution characteristic of Upper Shihezi Formation in the study area．It was determined that it mainly developed delta front deposits,and the underwater distributary channel was the skeleton sand body．On the whole，the reservoir properties of Upper Shihezi Formation are influenced by the provenance and sedimentary facies controlled by it，and its reservoir performance has comparative advantage in Upper Paleozoic strata.