旋流喷嘴钻头在NP32-3646井的现场应用分析

南堡32-3646井是一口四开三段制定向井,设计井深5798 m。3864~4265 m(井斜29.18°的稳斜段)试验了五刀翼旋流喷嘴PDC钻头(主切削齿直径16 mm,3个11 mm常规水眼和4个18 mm旋流喷射水眼)。针对深井超深井钻进中常采用的相对较高的钻井液密度和粘度,不利于提高钻头破岩效率的问题,在系统介绍旋转射流发生机理和破岩机理的基础上,对NP32-3646井五刀翼旋流喷嘴PDC钻头现场应用情况进行了分析。试验结果表明,旋转射流因具有切向、轴向和径向三维速度,可在高粘钻井液条件下更好地改善井底清岩效果,并通过剪切、冲蚀、拉伸和磨削等多种方式实现辅助破岩,从而提高钻井效率。试验钻头进尺401 m,平均机械钻速4.45 m/h,可较好地满足现场钻进需要,具有良好的推广应用前景。

Analysis on Field Application of Swirl Nozzle Bit Employed for NP32-3646 Well Drilling

NP32-3646 is a three-interval and four-spud directional well with designed depth of 5798m. The swirl nozzle PDC bit was tested in the section of 3864m to 4265m (well deviation angle of 29.18 ), which had 5 drag blades with diameter of 16mm for its main cutters and 7 nozzles (3 ordinary ones and 4 swirl ones with 11mm and 18mm in diameter respectively). In deep and extra-deep well drilling, higher mud density and viscosity are usually employed, which is against to improve bit drilling efficiency. To address this issue, based on the produce mechanism and rock-breaking mechanism of swirling jet flow, the analysis is made on the field application of swirl nozzle PDC bit with 5 drag blades in well NP32-3646. The field application indicates that duo to its three-dimensional velocity of tangential, axial and radial, swirling jet flow can improve the cuttings removal performance at well bottom and rock-breaking can be realized by shear, erosion, stretching and grinding so as to improve drilling efficiency. The swirl nozzle bit obtained a total footage of 401m with average rate of penetration of 4.45m/h, which can meet the needs of field drilling and has good popularization and application prospect.