This test was first proposed by Lubinski in 1958 and is the quickest method of finding the WOB and RPM combination for maximizing ROP. To get the best combination,it is desired that the test be carried out.

1. Drill- off Test"-
Selection of
Weight on Bit and
Rotary Speed

2. When to carry out Drill- Bit Test:
• Drill-bit test needs to be done at the start of
bit run
• On encountering a new formation
• If there is a reduction in ROP

3. Step 1
Maintaining a constant RPM, WOB
(near maximum available)

4. Step 2
Record the time required to drill a weight
increment for example: 2000 kg

5. Step 3
Length of pipe drilled during step 2 is needs
to be recorded

6. Step 4
From step 2 & 3, the drilling rate in
meter per hour has to be calculated.

7. Step 5
Step 2 & 3 are repeated at least four
times. The last test should be at the
same value as first.

8. Step 6
Penetration rate versus bit weight is
plotted.

9. Step 7
The bit weight which produced the
fastest ROP is selected.

10. Step 8
ROP versus RPM is plotted and the
RPM which resulted in the fastest ROP
is selected. This is the optimum rotary
speed.

11. Step 9
These values for RPM and WOB
obtained will result in optimum ROP
for the particular formation and bit
type.