Introduction

Rate of penetration(ROP) depth based is the average length of time used to deepen a certain depth of the borehole. For depth based ROP, typical units used are minutes/hours per foot and minutes/hours per meter. In our approach, depth based ROP is estimated by using block height data and its corresponding times. Scenarios that introduce calculation errors, such as stuck pipe, pipe elongation, are not taking into account. Rate of Penetration is only calculated during drilling activity. ROP could be used in bit selection, event detecting and etc.

Calculation Approaches

The first step to calculate rate of penetration depth based is to obtain block height data. In this example, depth based ROP in unit of hour per foot is showing. Equation could be manipulated to change resulting unit. Depth Interval is the unit drilled length ROP is desired to calculate over (time per depth interval).

The equation for calculating ROP hour/foot is:

depthIncrease_feet = blockHeight_feet(startTime)-blockHeight_feet(i);

rateOfPenetration_hrperft(i) = ((time_sec(i)-startTime)/3600)/depthIncrease_feet*depthInterval_feet;

where i is the number of data entry. DepthInterval_feet is entered to be 1 for resulting hour/foot unit. Note theoretically rate of penetration should not be negative since a borehole cannot be undrilled. ROP depth based during non-drilling activity is NaN.

Metadata Required

• Block Height – depth change of drill strings with corresponding time of recording.

• Rig State – calculation only performed in certain rig state activities

References

Adam, T. B., et al. "Applied drilling engineering." SPE Textbook Series, Dallas, TX 2 (1991).

American Association of Petroleum Geologists wiki, http://wiki.aapg.org/Rate_of_penetration.

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