DISCUSSION ON THE WELLBORE DEVIATION CONTROLLING IN AIR DRILLING

The penetration rate is rapidly increased by air drilling, but the wellbore deviation is not controlled easily. The paper introduces controlled and uncontrolled factors of influencing deviation in air drilling including BHA, bit weight, speed of rotation, formation anisotropism and stratigraphic dip etc. parameter, analyses control deviation technique of air hammer, discusses the reason of the deviation uncontrolled by air hammer in well Long 15. On the basis of the air drilling experiment in Qingxi oilfield, the result shows that fanning the bottom can achieve the goal of reduced deviation. It is a guide for design and operation of air drilling in future.