气体钻井井斜的原因及防斜技术

在归纳气体钻井井斜规律的基础上，对比分析了气体钻井与钻井液钻井两种情况下，地层各向异性、地层倾角、井眼几何参数及钻井参数等因素对井斜的影响。结果表明：气体钻井与钻井液钻井相比，地层各向异性显著增加是气体钻井容易井斜，且井斜后较难控制的根本原因；在中、大钻压下，井径扩大是气体钻井容易井斜的重要原因；而地层倾角、钻压、钻头切削各向异性和钻具组合对气体钻井井斜的影响与钻井液钻井相似。建议在现场推广应用空气锤、钟摆钻具组合和空气螺杆钻具组合三项气体钻井防斜技术来防止气体钻井井斜。

Causes of well deviation during gas drilling and its control

The well deviation law of gas drilling is induced and analyzed, the effects of formation anisotropy, formation dip, borehole geometry, and drilling parameters on well deviation during both gas drilling and mud drilling are compared and studied. The conclusion demonstrates that sharp increase in formation anisotropy is the root cause of the well deviation. And the borehole diameter enlargement is significant cause of well deviation during gas drilling under medium or high WOB. Formation dip, WOB, bit cutting anisotropy and BHA produce effects on gas drilled well deviation is in a similar way to mud drilling. It is recommended to adopt air hammer, pendulum assembly and air motor to minimize or eliminate the well deviation during gas drilling.