A sudden increase in the drill bit’s rate of penetration.
It sometimes indicates that the bit has penetrated a high-pressure zone and thus warns of the possibility of a kick.
A sudden increase in the rate of penetration during drilling.
When this increase is significant (two or more times the normal speed, depending on local conditions), it may indicate a formation change, a change in the pore pressure of the formation fluids, or both.
It is commonly interpreted as an indication of the bit drilling sand (high-speed drilling) rather than shale (low-speed drilling).
The fast-drilling formation may or may not contain high-pressure fluids.
Therefore, the driller commonly stops drilling and performs a flow check to determine if the formation is flowing.
If the well is flowing, or if the results are uncertain, the driller may close the blowout preventers or circulate bottoms-up.
Depending on the bit being used and the formations being drilled, a formation, even if sand, may sometimes drill slower rather than faster.
This slowing of drilling progress, while technically also a drilling break, is usually referred to as a “reverse drilling break”, or simply “reverse break.”