Formula
The casing capacity (annular volume) is calculated using:
$$\text{Annular Volume} = \frac{D_{h}^{2} - OD_{c}^{2}}{1029.4} \times L$$
Where:
- $D_h$ is the hole diameter (inches)
- $OD_c$ is the casing outer diameter (inches)
- $L$ is the hole length (feet)
- The constant 1029.4 converts the result to barrels
Example Calculation
For a hole with:
- Hole Diameter: 10 inches
- Casing Outer Diameter: 6 inches
- Length: 4,000 feet
$$\text{Annular Volume} = \frac{10^{2} - 6^{2}}{1029.4} \times 4{,}000$$
$$\text{Annular Volume} = \frac{100 - 36}{1029.4} \times 4{,}000$$
$$\text{Annular Volume} = \frac{64}{1029.4} \times 4{,}000 = 248.8 \text{ barrels}$$
About This Calculator
This calculator determines the annular volume capacity between the wellbore and casing in oil and gas drilling operations. The annular volume is the space between the outside of the casing and the wall of the drilled hole, which is critical for calculating cement volumes and understanding fluid requirements during drilling operations.
Applications
- Cement Volume Calculations: Determining the amount of cement needed to fill the annular space
- Drilling Fluid Planning: Calculating mud volumes required for the annulus
- Well Control: Understanding annular capacities for pressure calculations
- Workover Operations: Planning fluid displacement and circulation volumes