The drill-stem sub acts for conversion and connection of drill stem component in petroleum , nature gas and geology drilling work . It is used mainly for connecting of upper drill tools and lower drill tools during drilling operations. It is made of high strength alloy steel,and it is complied with API standard
The Drill-Stem Sub in 4 type of main structure
| No. |
Description |
Upper Connecting Part |
Lower Connecting Part |
Type |
| 1 |
Kelly sub |
Kelly |
Tool Joint |
A or B |
| 2 |
Tool Joint Sub |
Tool Joint |
Tool Joint |
A or B |
| 3 |
Crossover Sub |
Tool Joint |
Drill Coller |
A or B |
| 4 |
Drill Collar Sub |
Drill Coller |
Drill Coller |
A or B |
| 5 |
Bit Sub |
Drill Coller |
Bit |
A or B |
| 6 |
Swivel Sub |
Swivel Lower Sub |
Kelly |
c |
| 7 |
Fishing Sub |
Kelly |
Tool Joint |
c |
| Tool Joint |
Fishing tools |
c | |
