Drilling Cost Calculator

A slower rate of penetration means more hours are needed to reach the same total depth, and since the rig is rented by the day regardless of how fast it's actually drilling, more hours directly translates into more days billed at the rig day rate. This is why rate of penetration, purely a speed measurement, still has a real and often substantial effect on the final dollar total.

Casing and drilling fluid programs vary too much between wells based on design choices — casing string diameters, the number of casing strings, mud weight and chemistry needs — to reduce sensibly to a single per-foot rate the way a relatively standardized bit and service cost can be. Entering them as flat totals reflects that these costs are typically estimated separately by the drilling engineer for each specific well design.

Total cost is driven partly by how deep the well is, so a deeper well naturally costs more even when drilled efficiently — comparing raw totals across wells of different depths doesn't tell you much about execution quality. All-in cost per foot normalizes for depth, making it the more useful number for comparing efficiency between wells, rig contractors, or drilling programs of different sizes.

Trip time and drilling time are added together before being converted into billed rig-days, so from a cost perspective they're equally weighted — an hour spent tripping pipe costs exactly as much as an hour spent actively drilling, since the rig rental clock doesn't distinguish between the two. On wells with deep or complex trajectories requiring frequent trips, that non-drilling time can end up representing a substantial share of total rig cost.