In the practice of shale gas development engineering, it is important to understand the physical and mechanical properties of shale. The bedding inclinations of shale are known to significantly influence its physical and mechanical properties. This study mainly examined the influence of bedding inclinations on drillability under different wellbore pressures. The bedding inclinations used in this study varied from 0° to 90°, with a gradient of 15°. The wellbore pressure values used varied from 0 to 25 MPa, with a gradient of 5 MPa. The results show that the drillability index of shale increases exponentially with increasing wellbore pressure at different bedding inclinations. The proposed exponential empirical model can describe the relationship between the drillability index and wellbore pressure. When the wellbore pressure is less than 15 MPa, bedding inclinations significantly influence the drillability index, and the drillability index of shale shows a “W”-type variation trend as the bedding inclinations increase in the range of 0° to 90°. The influence of bedding inclinations on drillability decreases gradually with increasing wellbore pressure. When the wellbore pressure increases to 25 MPa, the impact of bedding inclinations on drillability is virtually undetectable. The results of this study can provide reasonably insight into the effect of bedding inclinations on shale deformation under the drill bit, and useful prediction for the drillability index under in situ conditions.

在页岩气开发工程的实践中，重要的是要了解页岩的物理和机械性能。已知页岩的层理倾向会显着影响其物理和机械性能。这项研究主要研究了层理倾角对不同井眼压力下可钻性的影响。本研究中使用的床上用品倾斜度从0°到90°不等，倾斜度为15°。所使用的井眼压力值在0到25 MPa之间变化，梯度为5 MPa。结果表明，在不同层理倾角下，页岩可钻性指数随井筒压力的增加呈指数增长。所提出的指数经验模型可以描述可钻性指标与井眼压力之间的关系。当井筒压力小于15 MPa时，层理倾角显着影响可钻性指标，并且随着层理倾角在0°至90°范围内增加，页岩的可钻性指标显示出“ W”型变化趋势。随着井眼压力的增加，层理倾角对可钻性的影响逐渐减小。当井眼压力增加到25 MPa时，几乎无法检测到地层倾角对可钻性的影响。这项研究的结果可以合理地了解层理倾角对钻头下页岩变形的影响，并为就地条件下的可钻性指标提供有用的预测。随着井眼压力的增加，层理倾角对可钻性的影响逐渐减小。当井眼压力增加到25 MPa时，几乎无法检测到地层倾角对可钻性的影响。这项研究的结果可以合理地了解层理倾角对钻头下页岩变形的影响，并为就地条件下的可钻性指标提供有用的预测。随着井眼压力的增加，层理倾角对可钻性的影响逐渐减小。当井眼压力增加到25 MPa时，几乎无法检测到地层倾角对可钻性的影响。这项研究的结果可以合理地了解层理倾角对钻头下页岩变形的影响，并为就地条件下的可钻性指标提供有用的预测。