逆掩推覆体防斜打快钻具组合探索与认识

STUDIES ON SLANTING CONTROL & FAST DRILLING BHA IN THE OVERTHRUST NAPPE FORMATION

逆掩推覆体地层具有斜、硬、跳、磨、变等特点 ,常规的钟摆降斜钻具既不能使用大钻压加快钻井速度 ,又不能有效地控制井斜 ,在坚硬的地层中只能轻压吊打 ,严重制约了钻井速度 ,增加了钻探成本。为加快窿 9井在逆掩推覆体地层中的钻进速度、控制井斜 ,探索性地应用了多稳定器稳斜钻具和MWD +导向钻具、偏轴钻具和悬浮钻井 ,结果表明 ,3种钻具组合都能够达到解放钻压 ,提高机械钻速的目的 ,但控制井斜的效果不太理想。分析了井斜控制不理想的原因 ,提出了利用地层自然造斜规律 ,通过钻定向井来解决逆掩推覆体地层钻井速度慢的难题。

Conventional pendulum drill-assembly is not efficient enough in drilling the over - thrust nappe formation which is slant and hard and causes such problems as bit jumping and drill tool friction; while only light WOB could be applied when drilling the hard formation which severely limits the penetration rate and adds up to the drilling cost. This paper focuses on the experimental application of several drill - assemblies when drilling the 311 mm hole in the over- thrust nappe in Well Qiong-9, specifically these assemblies are angle-holding assembly with multiple stabilizers and MWD plus steerable drill, eccentric drill and suspended drilling. Results show that all the three assemblies can improve ROP by applying high WOB, however, hole deviation control remains a problem. Possible causes of poor deviation control are analyzed and eccentric drill should be used; it is also an ideal alternative to drill directional well and extended reach well by taking the advantage of the natural slanting tendency in such formation.