The rate of penetration is calculated by well drillers, especially in the oil and gas industry, to describe the rate at which the well deepens as drilling moves forward. Depending on the measurement system used in the country where the well is drilled, the rate of penetration, or ROP, is typically stated in minutes per foot or feet per hour, or minutes per meter or meters per hour.
Record measured depth at the beginning of the time interval from the driller’s log. Consider these values Depth 1 and Time 1.
Record measured depth at the end of the time interval from the driller’s log. These numbers are Depth 2 and Time 2.
Subtract Depth 1 from Depth 2 to get the change in depth. For example, 4,040 feet - 3,812 feet = 228 feet.
Subtract Time 1 from Time 2 to get the time difference in hours and minutes. Convert from hours and minutes to decimal hours by dividing the number of minutes by 60. For example, four hours and 44 minutes = 4.733 hours.
Divide the depth difference by the time difference to obtain ROP in feet per hour. For example, 228 feet / 4.733 hours = 48.38 feet/hour.
Convert the time difference to minutes to begin obtaining the ROP in minutes per foot. Multiply the number of hours by 60 and add the number of minutes. For example, four hours x 60 minutes/hour + 44 minutes = 284 minutes.
Divide the time difference in minutes by the depth difference in feet to obtain ROP in minutes per foot. For example, 284 minutes / 228 feet = 1.24 minutes/foot.
Rate of penetration is tracked on most mud logs at a 15-minute interval.
