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- Title
差压步进钻头提高破岩速度原理及现场试验.
- Authors
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
- 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 reaming 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 region. 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%.
- Subjects
HYDRAULIC couplings; SERVICE life; COMPACTING; GRAVEL; SPEED
- Publication
Journal of China University of Petroleum, 2024, Vol 48, Issue 4, p101
- ISSN
1673-5005
- Publication type
Article
- DOI
10.3969/j.issn.1673-5005.2024.04.010