Accumulator Capacity – Usable Volume per Bottle Calculation for Subsea BOP

For subsea applications, hydrostatic pressure exerted by the hydraulic fluid must be accounted for calculation.

th_277868

In this case, we assume water depth at 1500 ft, therefore hydrostatic pressure exerted by hydraulic fluid (hydraulic fluid pressure gradient = 0.445 psi/ft) = 0.445×1500 = 668 psi. Besides of that, the concept for calculation is as same as surface accumulator. So please take a look about how to calculate usable volume per bottle as following steps.

Step 1 Adjust all pressures for the hydrostatic pressure of the hydraulic fluid:

Pre-charge pressure = 1000 psi + 668 psi = 1668 psi

Minimum system pressure = 1200 psi + 668 psi = 1868 psi

Operating pressure = 3000 psi + 668 psi = 3668 psi

Step 2 Determine hydraulic fluid required to increase pressure from pre-charge pressure to minimum system pressure:

Boyle’s Law for ideal gase: P1 V1 = P2 V2

1668 psi x 10 = 1868 x V2

16,680 ÷1,868 = V2

V2 = 8.93 gal

It means that N2 will be compressed from 10 gal to 8.93 gal in order to reach minimum operating pressure. Therefore, 1.07 gal (10.0 – 8.93 = 1.07 gal) of hydraulic fluid is used for compressing to minimum system pressure.

Step 3 Determine hydraulic required increasing pressure from pre-charge to operating pressure:

P1 V1 = P2 V2

1668 psi x 10 gal = 3668 psi x V2

16,680 ÷ 3668 = V2

V2 = 4.55 gal

It means that N2 will be compressed from 10 gal to 4.55 gal in order to reach operating pressure. Therefore, 5.45 gal (10.0 – 4.55 = 5.45 gal) of hydraulic fluid is used for compressing to operating pressure.

Step 4 Determine usable fluid volume per bottle:

Usable volume per bottle = Total hydraulic fluid/bottle – Dead hydraulic fluid/bottle

Usable volume per bottle = 5.45 – 1.07

Usable volume per bottle = 4.38 gallons

Reference book: Well Control Books

Drilling Formula Book Formulas and Calculations for Drilling, Production and Workover, Second Edition

Related Post

Effect of Frictional Pressure on ECD while reverse... A reverse circulation is another way to circulate by circulating into annulus up to a bit and drill string. The fluid outlet is at stand pipe side. Fo...
Learn About Drill Pipe Float Valve A drill pipe float valve is a check valve installed in the drill stem that allows mud to be pumped down but prevents flow back up. There are two types...
Annular Velocity and Its Importance to Drilling Hy... Annular velocity is the speed of fluid moving up the annulus and it must be high enough to transport cuttings generated while drilling from the wellbo...
Balanced Cement Plug Calculation You already learn about balance cement plug and I would like to show how to calculate balance cement plug.  Let’s start with the concept so you can...
Share the joy
  • 2
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
    2
    Shares
Tagged . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

2 Responses to Accumulator Capacity – Usable Volume per Bottle Calculation for Subsea BOP

  1. fein blade says:

    thanks for your sharing, please bookmark this page in digg or mixx because I can find it easily
    thank you

  2. Balenciaga outlet says:

    Hello, your articles here Accumulator Capacity – Usable Volume per Bottle Calculation for Subsea BOP‎ to write well, thanks for sharing!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.