储层速敏效应形成机理及其垂向差异因素分析——以塔北隆起吉拉克地区三叠系储层为例

Formation mechanism and vertical distribution of velocity sensitivity effect in reservoir: An example from Triassic sandstone reservoir in Jilake area, Tabei uplift

轮南吉拉克地区三叠系TⅡ24小层表现出强速敏效应,且速敏损害率高值主要集中于TⅡ24小层的上部(TⅡ24-2单层和TⅡ24-1单层),垂向差异特征明显。通过显微薄片观察,结合X射线衍射荧光光谱和毛管压力曲线测试分析,分别从宏观和微观的角度探讨引发层段内强速敏效应的形成机理。研究认为,含量较高的黏土矿物以及岩浆岩岩屑的溶蚀残余颗粒,是研究层段内易迁移微小颗粒的主要来源,而孔喉结构参数也表明研究层段内孔喉连通性整体较差,这两方面因素是强速敏效应的主控因素;另外,上述控制因素在垂向上表现出明显的差异性,黏土矿物相对富集于TⅡ24小层的上部,而孔喉连通性也在TⅡ24小层的上部相对较差,两者共同构成了速敏损害率垂向差异的主控因素。

As a main production layer of Jilake area in Tabei uplift, the TII24 layer is subject to a considerable variety of velocity sensitivity. The higher values of the velocity sensitivity effect are concentrated in the upper part of the TⅡ24layer（single sand layers of TⅡ24-1and T Ⅱ24-2）, showing a marked vertical disparity. The formation mechanism of velocity sensitivity effect within the layer was thoroughly analyzed from macroscopic and microscopic perspective by means of observing thin section, analyzing the X-ray fluorescence spectra and measuring the capillary pressure curve.The result shows that high content of clay minerals and the remaining particles of dissolved volcanic grains constitute the main source of the transmittable particles within the layer. The pore throat structure parameters indicate pore throat connectivity is relatively poor. The two aspects mentioned above are the main controlling factors for the strong velocity sensitivity. Relatively high content of clay minerals and comparatively poor pore throat connectivity in the upper part of the TII24 layer are the key controlling factors for the vertical disparity of the velocity sensitivity damage.