空气钻井井斜问题与地层倾角的规律探讨

由于可以有效的保护储层、防止井漏和大幅度提高钻井速度等优点使得空气钻井得到迅速发展，然而在一些地层的钻进过程中，使用空气钻井时出现了在钻井液钻井时不会出现的井斜问题。针对这一问题，采用弹塑性有限元法建立了空气钻井和钻井液钻井中井筒在不同地层倾角情况下的高度非线性力学分析模型，重点从岩石力学的角度分析和探讨了空气钻井中井筒岩石的应力分布、破岩趋势以及井斜与地层倾角的变化关系，得到了空气钻井的井斜规律；同时与钻井液钻井进行了比较，证明了空气钻井比钻井液钻井更易发生井斜的观点。

Discussion on the Rule of Well Deviation and Stratigraphic Dip in Air Drilling

Using air drilling technique can effectively control formation damage, leak protection and improve the rate of penetration. But well deviation of air drilling is a problem in some place where drilling has no problem with mud. In this paper, a series of high non-linear elastoplasticity finite element model were established to simulate well hole of air drilling and mud drilling under different stratigraphic dip. The stress distribution, rock-breaking trend and the changement relationship of deviation and the stratigraphic dip of rock in well bore were analyzed and discussed in air drilling, and the well deviation laws of air drilling were obtained. Meantime, compared with mud drilling, well deviation in air drilling is easier than do in mud drilling.