鄂尔多斯盆地延长组张家滩陆相页岩各向异性及能量演化特征

为揭示鄂尔多斯盆地延长组张家滩陆相页岩各向异性及其对井壁失稳的影响，首先应用扫描电镜对页岩的微观孔隙结构进行分析；后钻取标准岩样，开展室内声学、力学试验，研究陆相页岩声学、力学及能量演化特征的各向异性。结果表明：鄂尔多斯盆地延长组张家滩陆相页岩孔隙和裂缝的类型及发育程度在不同层理方向存在明显差异；页岩声学、力学参数及能量演化特征均具有极强的各向异性。钻井方向与层理法线的夹角对页岩地层井壁稳定性有一定影响。该研究成果可为页岩气水平井井身结构设计及现场工程应用提供技术参考。

Anisotropy and energy evolution characteristics of Zhangjiatan continental shale of Yanchang Formation in Ordos Basin

In order to reveal the anisotropy of Zhangjiatan continental shale of Yanchang Formation in Ordos Basin and its influence on wellbore instability,microscopic pore structure was analyzed by means of scanning electron microscopy(SEM),and then laboratory acoustic and mechanical experiments based on standard rock samples were conducted to study the anisotropy of acoustic and mechanical parameters as well as energy evolution characteristics of continental shale. The results show that the types and abundances of pores and fractures are obviously various in different bedding plane directions in Zhangjiatan continental shale of Yanchang Formation in Ordos Basin. Acoustics and mechanical parameters and energy evolution characteristics of shale are strongly anisotropic. The angle between drilling direction and normal of bedding planes has a certain influence on wellbore stability in shale formation. The research results can provide technical references for the optimization design of wellbore structure of shale gas horizontal well and engineering application.