Annular capacity and volume
Volume per metre and over an interval of the annulus between the hole (or casing) and the pipe.
C_a = π/4 · (D² − d²)V_a = C_a · LTool joints and couplings reduce the annular volume by a few percent. For several sections, compute each interval (in casing, in open hole, around the collars) and add them up.
Source: Annulus geometry
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
For open hole, the bit size or the caliper average.
Unit converter for this formulaLength · Volume per length (capacity) · Liquid volume
- m1
- cm100
- mm1,000
- km0.001
- ft3.28084
- in39.3701
- 1/32 in1,259.84
- 1/64 in2,519.69
- mile0.000621371
- V_a — Annular volume–
More in Drill string and volumes
Internal volume per metre and for the whole string, metal (open-end) and closed-end displacement — for the trip sheet: hole fill when pulling and returns when running in.
String weight in air and in mud (buoyancy factor) for one or two pipe sections, and the hook load including the travelling block and top drive.
Fast-line and dead-line tension, derrick load and the rope breaking strength needed to lift the string on n lines, allowing for the efficiency of the block and tackle.
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.