中国石油大学学报（自然科学版）2024，Vol.48Issue(4)：101-108,8.DOI:10.3969/j.issn.1673-5005.2024.04.010
差压步进钻头提高破岩速度原理及现场试验
Mechanism and field testing of improving rock breaking efficiency by using a step-type drilling bit with self distributing of drilling pressure
摘要
Abstract
The rock at the bottom of the well bears large in-situ stress,and it increases with the increase of the well depth.The in-situ stress can cause compaction of the rock,resulting in problems during well-drilling,such as poor drillability and strong abrasiveness,which is one of the main reasons for low cutting efficiency,short service life and slow drilling speed of rock breaking tools.In this study,a novel method was proposed for releasing in-situ stress at the bottom of the well to weaken the drilling resistance of the formation and improve the rock breaking speed,and a step-type bit was developed.The bit makes full use of the fluctuation of the weight on bit(WOB)to achieve the goal of dynamic distribution of WOB between rea-ming bit and leading bit during alternate drilling process.The rock breaking efficiency of the new bit can be improved by three effects,namely,weakening the rock formation,strengthening the impact and transforming the vibration.In order to verify the stress release effect of the step-type bit,a three-dimensional fluid solid coupling stepped bottom hole stress field model was established,and the field tests of three wells were carried out in the gravel formation of a block in Jiangsu oil re-gion.The results show that the rock at the step is more easily to break.The bit with small diameter leading bit has better stress release effect.With the increase of formation depth,the stress release effect of the step-type bit is more significant,and the stress release ratio is about 60.2%.The drilling speed of the step-type bit is significantly increased.The drilling speed is increased by 161.89%compared to the cone bit,with a maximum increase of 318.11%.关键词
钻井/井底原地应力/地层抗钻特性/差压步进钻头/应力释放/岩石破碎Key words
well drilling/downhole in-situ stress/formation drilling resistance/step-type drill bit with self distributing of drilling pressure/stress release/rock fragmentation分类
能源科技引用本文复制引用
刘永旺,李坤,管志川,刘嘉雄,呼怀刚,陈小元,王委,赵国山,张曙辉..差压步进钻头提高破岩速度原理及现场试验[J].中国石油大学学报（自然科学版）,2024,48(4):101-108,8.基金项目
国家重点研发计划政府间国际科技创新合作重点专项(2021YFE0111400) （2021YFE0111400）
中石油重大科技项目(ZD2019-183-005) （ZD2019-183-005）
国家自然科学基金面上项目(52074324,51974320) （52074324,51974320）
中央高校基本科研业务费专项(19CX02065A) （19CX02065A）
