Extension Limit of a Straight-Swirling Mixed Jet Bit and Its Influential Factors in Radial Jet Drilling
Radial jet drilling (RJD) is applied to low-permeability and unconventional natural gas. A self-propelled bit chiefly affects the borehole length and drilling efficiency. Herein, for a straight-swirling mixed jet (SSMJ) bit, a prediction model of the drilling extension limit LEL was established by a...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2022-01-01
|
| Series: | Geofluids |
| Online Access: | http://dx.doi.org/10.1155/2022/3078233 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Radial jet drilling (RJD) is applied to low-permeability and unconventional natural gas. A self-propelled bit chiefly affects the borehole length and drilling efficiency. Herein, for a straight-swirling mixed jet (SSMJ) bit, a prediction model of the drilling extension limit LEL was established by analysing the forces and pressure loss of RJD system. LEL of a specific project was calculated and the pressure loss and forces distribution were obtained. Additionally, the influence laws of the main factors on LEL were studied using the established model. The results indicated that the high-pressure hose contributes the main system pressure loss, and the recoil force of backward nozzles is the sole driving force of RJD. The recoil force of forward nozzle and friction between the hose and borehole constitute the main resistances. Increasing the pump pressure pb, backward nozzle diameter db, and jet diffusion angle θx and reducing forward nozzle diameter df, impeller central hole diameter dm, and backward nozzle inclination angle θb are conducive to improving LEL. However, larger pb and db increase the hydraulic consumption, besides larger θx or smaller df, and dm will reduce the rock-breaking capability. From a sensitivity analysis, pb and dm have the maximum and minimum influence on LEL, respectively. Finally, prediction value LEL of an oil well in Eastern Sichuan can be up to 63.7 m. The results provide a guidance for the hydraulic parameters and key component selection, additionally bit structure optimization of RJD. |
|---|---|
| ISSN: | 1468-8123 |