Accumulator Capacity - Usable Volume per bottle

Description:

In drilling operations, an accumulator is used to store hydraulic fluid under pressure, which is essential for operating various drilling equipment and control systems like Rams BOP, Annular BOP. The usable volume per bottle refers to the effective volume of hydraulic fluid that can be utilized from each accumulator bottle.

This volume is crucial for ensuring that the accumulator system has sufficient capacity to handle the hydraulic demands of the drilling operations.

Equation:

Usable Volume per bottle (V): $$ V_{usable} = V_{total} \times \left(\frac{P_{pre.charge}}{P_{min.system}} - \frac{P_{pre.charge}}{P_{operating}}\right) $$ For subsea application: $$ P_{actual} = P + \rho \times D_{waterdepth} $$

Where:

\( V \) = Usable Volume per bottle (gal)      \( V_{total} \) = Volume per bottle (gal)

\( P_{pre.charge} \) = Pre-charge pressure (psi)

\( P_{min.system} \) = Minimum system pressure (psi)

\( P_{operating} \) = Operating Pressure (psi)

\( \rho \) = Pressure gradient of hydraulic fluid (psi/ft)

\( D_{waterdepth} \) = Water Depth (ft)

Practical Consideration:

This formula helps in determining how much of the accumulator's total volume can be practically used during drilling operations.