以井斜趋势角为指标优化防斜钻具设计

应用钻头与地层相互作用模型，综合考虑钻头和地层各向异性、钻头侧向力及钻头转角对井斜的影响，提出了“井斜趋势角”概念。针对各向同性地层，推导了“井斜趋势角”计算公式。分析表明：进行防斜钻具设计、优选钻井参数时，综合考虑侧向力、钻头转角及钻头各向异性等因素对井斜的影响是十分必要的；与“钻头侧向力最大”或“钻头转角最小”等单一指标相比，“井斜趋势角”指标考虑因素更全面、设计(或评价)结果更可靠。

Optimizing the Design of Bottom-Hole Assembly in Deviation Control by the Trend Angle of Deviation

Based on the bit-rock interaction model, a new term named the trend angle of deviation (TAD) in deviation control was brought forward, where anisotropic characteristics of bit and rock, the bit lateral force as well as and the effect of bit tilt angle on hole deviation were taken into account synthetically. In addition, simple and practical formulae were derived for isotropic formations. Conclusions were drawn as follows: 1) When designing the bottom-hole assembly (BHA) in deviation control and optimizing drilling parameters (weight-on-bit, rotary speed etc), it was essential to take all factors above into account. 2) Compared with the single criteria such as the maximum bit lateral force or minimum bit tilt angle, the TAD criteria was more comprehensive and more reliable.