Drilling cost per foot is the total drilling cost per footage drilled. This value is used for evaluating drilling projects, bit performance, drilling performance, etc.

Drilling Cost Per Foot – (OilfieldPix.com,2017)

The formula for drilling cost per foot as shown below;

CT = (B + CR (t + T)) ÷ F

Where:
CT = drilling cost per foot
B = bit cost
t = drilling time
CR = Rig cost per hour. This number must include all fixed daily cost not just only drilling contractor rate.
T = round trip
F = footage drill

Example: Determine the drilling cost per foot (CT) using the following data:

Bit cost (B) = 27,000 $
Drilling time (t) = 50 hours
Rig cost (CR) = $3500/hour
Round trip time (T) = 12 hours
Footage per bit (F) = 5000 ft

CT = (27,000 + 3,500 (50 + 12)) ÷ 5000
CT = 48.8$ per foot

Please find the excel sheet for calculating drilling cost per foot.

Ref books: Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.