Shale gas exploration and development have become a hot spot in the natural gas industry. Providing wellbore stability is one of the major engineering problems occurring in the process of drilling of horizontal shale gas wells. In this paper, based on circumferential stress analysis of horizontal wells and analysis of the geometrical relationship of bedding planes and the wellbore, a new horizontal wellbore stability model is introduced. The proposed model takes into account the effect of bedding planes and water content on the strength parameters of shale. Based on actual field data of a shale gas well, the proposed model is compared with the wellbore stability model for an intrinsic rock formation. The results show that the existence of bedding planes affects the stability of a wellbore, making it less stable. Meanwhile, the maximum and minimum values of collapse pressure density for different azimuths of wellbore increase linearly with increase in water content. Moreover, the results also show that factors of the wellbore azimuths and the bedding planes dip angle and dip direction have a significant impact on the wellbore stability of horizontal shale gas wells.

中文翻译：

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受层理面和含水量影响的页岩气水平井井筒稳定性新模型

页岩气勘探开发已成为天然气行业的热点。提供井筒稳定性是页岩气水平井钻井过程中出现的主要工程问题之一。本文在水平井周向应力分析和层理面与井筒几何关系分析的基础上，引入了一种新的水平井筒稳定性模型。该模型考虑了层理面和含水量对页岩强度参数的影响。基于页岩气井的实际现场数据，将所提出的模型与固有岩层的井筒稳定性模型进行了比较。结果表明，层理面的存在会影响井筒的稳定性，使其稳定性较差。同时，井筒不同方位的坍塌压力密度最大值和最小值随着含水量的增加而线性增加。此外，研究结果还表明，井筒方位角、层理面倾角和倾角等因素对页岩气水平井井筒稳定性有显着影响。