成岩作用和岩石结构对砂岩弹性速度的影响

Effects of diagenesis and rock texture on elastic velocity of sandstones

对济阳坳陷沙河街组Es3z地层的127块砂、泥岩岩心样品进行了实验测试,利用速度—孔隙度关系,研究了成岩作用(胶结物)、岩石结构(分选性和黏土含量)对砂岩弹性速度的影响及其在速度—孔隙度关系中的变化形式。研究结果表明:速度—孔隙度关系的变化主要受成岩作用(钙胶结物)的影响,砂岩速度与胶结物含量具有明显的正相关性。岩石结构(分选性和黏土含量)控制了岩石速度和孔隙度的次一级变化。根据定性和定量分析,利用特定岩石物理参数的变化代表储层岩石沉积学特征,给出了胶结物、分选性和黏土含量对地震速度属性影响的理论岩石物理模型。

The 127 samples of sandstone and shale in the third member of Shahejie Formation in Jiyang Sag were measured to investigate the influence of sedimentation on the elastic properties of sandstone. The effects of diagenesis and rock texture on the elastic velocity of sandstones and its variation pattern in velocity-porosity plane were studied according to the velocity-porosity relationship. The result shows that variation of the elastic velocity with porosity of sandstone is mainly controlled by diagenesis. The elastic velocity of sandstone is positively correlated to cementation content in rock. The rock textures such as sorting property and clay content are the secondary factor affecting the velocity of sandstone. A theoretical model of rock physics was provided to simulate the effects of cementation, sorting property and clay content on seismic velocities based on the qualitative and quantitative analysis and using the change of special rock physical parameters representing the sedimentological properties of reservoir.