硬脆性泥页岩井壁稳定研究进展

Research progress of wellbore stability in hard brittle shale

赵凯 樊勇杰 于波 韩继勇 许永华 高诗惠

ZHAO Kai FAN Yongjie YU Bo HAN Jiyong XU Yonghua GAO Shihui

西安石油大学石油工程学院 长庆油田公司第三采油厂采油工艺研究所

College of Petroleum Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China Oil Production Technology Research Department,

硬脆性泥页岩的井壁失稳是制约深层油气资源和页岩气等非常规油气资源有效开发的关键问题。基于此，从硬脆性泥页岩的基本特征出发，根据其组成成分和结构特征的差异，总结了纯力学、渗流– 应力耦合和渗流– 应力– 化学耦合3 种井壁稳定基本分析方法及各自适用条件。研究了硬脆性泥页岩4 种力学失稳机制、钻井液侵入裂缝的驱动作用、存在和不存在活性黏土矿物情况下强度弱化机制以及不同裂缝形式下的井壁稳定计算模型。指出硬脆性泥页岩基质和裂缝充填物中是否含活性黏土矿物及裂缝的分布规律是影响井壁稳定分析的关键因素，从微观角度描述多场耦合作用下硬脆性泥页岩裂缝扩展连通导致井壁失稳的渐进过程将成为未来研究的热点和难点。

Wellbore instability in hard brittle shale is a key problem restricting the effective development of deep resources and unconventional resources (e.g. shale gas). In this regard, this paper presents the basic analysis methods of wellbore stability under three scenarios (i.e. mechanics, stress-seepage coupling and seepage-stress-chemical coupling) and their application conditions, with consideration to the features, composition and structure of hard brittle shale. This paper also discusses four mechanical instability mechanisms of hard brittle shale, the driving action for drilling fluid invading into fractures, the strength weakening mechanism with and without active clay mineral, and the calculation model for wellbore stability with different forms of fractures. It is concluded that the key factors influencing wellbore stability analysis are the existence of active clay minerals in hard brittle shale matrix and fracture fillings and the fracture distribution laws. Microscopic description of the progressive wellbore instability process which is induced by propagation and connection of fractures in hard brittle shale under the action of multiple-field coupling will become a hotspot and difficulty in future research.

10.13639/j.odpt.2016.03.001