Volume of a tubular
A quick way to get the barrel per foot volume of a tubular is to square the inside diameter of the tubular and divide by 1029.4
This is just another way of saying D x D x .7854 x 12 /231/42 except if you do that using 1.0 as the diameter value you end up with 0.000971 …. so what’s the deal?
Here is the story; 0.000971 is hard to remember, you cant easily recall it from the top of your head; It would be complicated to say “one times one times ‘point oh oh oh nine seven one'”…. anyway leave it to the oilfield to figure out an easier way.
The reciprocal value of 0.000971 is 1029.4 [ 1/0.000971] and ‘ten twenty-nine point four’ is easy to remember… so instead of multiplying diameter squared times 0.000971; you just divide by 1029.4 and you get the same result.
Try it out – 4.5″ 11.6# casing has an internal diameter of exactly 4.000” so 16 x 16 / 1029.4 = .01554 Barrels per foot. Perfect. Just commit ‘Ten Twenty-nine point Four’ to memory and you will be ‘all knowed up’ about volumes.
You can still do it the hard way and figure out the cubic inches of the cross sectional area, and multiply by length to get the volume, then divide by 231 cubic inches to get gallons and then divide again to get barrels of fluid.