After learning about capacity calculation, we can apply the capacity calculation to determine how much barrels of cutting produced per foot of hole drilled and total solid generated in pounds. Please read and understand the following formulas:
Use formular#1 and #2 for calculating amount of cutting generated per feet drilled.
Formula#1 for BARRELS of cuttings drilled per foot of hole drilled:
Barrels of cutting per foot drilled = Dh2 x (1 – % porosity) ÷1029.4
Where: Dh is hole diameter.
Example: Determine barrels of cuttings drilled for one foot of 6-1/8 inch hole with 25% (0.25) porosity:
Barrels/footage drilled = 6.1252 x (1 – 0.25) ÷1029.4
Barrels/footage drilled = 0.02733 bbl/footage drilled
Formula#2 for CUBIC FEET of cuttings drilled per foot of hole drilled:
Cubic feet of cutting per foot drilled = Dh2 x 0.7854 x (1 – % porosity) ÷144
Where: Dh is hole diameter.
Example: Determine barrels of cuttings drilled for one foot of 6-1/8 inch hole with 25% (0.25) porosity
Cubic feet/footage drilled = 6.1252 x 0.7854 x (1 – 0.15) ÷144
Cubic feet/footage drilled = 0.153462 cu ft/footage drilled
Moreover, you also apply simeple density and volume relationship to determine total solids generated. Use the following formula to calculate total solid generated.
Wcg = 350 x Ch x L x (l – porosity) x Cutting density
Wcg = solids generated in pounds
Ch = capacity of hole in bbl/ft
L = footage drilled in ft
Cutting density = cutting density in gm/cc
Example: Determine the total pounds of solids generated in drilling 100 ft of 6-1/8 inch hole (0.03644 bbl/ft). Density of cuttings = 2.20 gm/cc. Porosity = 25%:
Wcg = 350 x 0.03644 x 100 x (1 – 0.25) x 2.2
Wcg = 2104.41 pounds
Ref book: Formulas and Calculations for drill, production and workover by Norton J. Lapeyrouse
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