松辽盆地徐家围子断陷沙河子组物源特征及对储集砂体的控制作用

综合砂岩轻、重矿物组成和砾岩砾石成分分析，在明确松辽盆地徐家围子断陷不同构造单元母岩性质的基础上，结合地震特殊反射特征建立各构造单元物源方向，明确物源对储集砂体展布、物性形成的控制。结果表明：①安达地区母岩为西北部安达凸起的酸性火山岩，物源方向为南西向；徐西凹陷母岩为西部中央古隆起的酸性、中基性火山岩，物源方向以东西向为主；宋站地区和徐东凹陷母岩为徐东斜坡的中基性火山岩和变质岩，物源方向以北东向、东西向为主。②西部、西北部物源规模较小，在断陷西侧陡坡带形成一系列沿断裂呈孤立点状分布的扇三角洲沉积体，砂体厚度大但延伸距离短；东部物源规模较大，在断陷东侧缓坡带形成连片叠置的辫状河三角洲沉积，砂体较薄但平面分布广。③西部陡坡带砂体粒度粗，抗压实能力强，在深埋条件下仍保留部分原生孔隙；东侧缓坡带砂体碎屑颗粒细、岩屑等塑性组分含量高，压实减孔严重，但紧邻煤层和湖相泥岩环境有利于有机酸进入造成岩屑、长石广泛溶蚀，极大地改善了储层物性。

Characteristic of provenance and their control over sand bodies in Shahezi Formation of Xujiaweizi fault depression,Songliao Basin

The characteristic of parent rock in different tectonic unit was investigated according to the composition of clastic rock, heavy mineral and conglomerate. The main direction of different tectonic units was established based on special reflection analysis, and their impacts on the distribute and quality of sand bodies were clarified. The result is that, the parent rock in Anda area is mainly acid volcanic rock which comes from Anda Sag, and the parent rock in Xuxi Depression is mainly acid and intermediate-basic volcanic rock which comes from the central uplift. The parent rock in Songzhan area and Xudong Depression is intermediate-basic volcanic and metamorphic rocks that comes from Xudong slop. The scale of provenance in sleep slop such as Anda area and Xuxi Depression is less than that in gentle slope belt such as Songzhan area and Xudong Depression, therefore, the sedimentary facies in Anda area and Xuxi Depression are small fan delta which was developed along with Xuxi fault, and isolated from the other. While the sedimentary facies in Songzhan area and Xudong Depression is braided river delta in large scale, with a small thickness and wide area. The size of sandstone in sleep slop are greater than that in gentle slope belt, which makes the sandstone have a stronger ability to resist the compaction, and lots of primary pores can be reserved at a higher burial depth, while for the sandstone in gentle slope belt with a greater content of rock debris and smaller size, in that case, a great deal of porosity have been lost because of serious compact and primary pore can hardly be found in gentle slope belt. But organic acids get into reservoir and corrode rock debris, generate masses of dissolution pores which is the key factor why quality of sandstone in gentle slope belt is higher than that in sleep slope.