Calculate Bottles Required for Koomey Unit (Accumulator Unit)

This topic will demonstrate you how to determine accumulator bottles required for Koomey Unit (Accumulator Unit) in order to close the surface BOP stack.

This is a specification of Accumulator (Koomey) Unit.

Accumulator 3,000 psi system

Volume each bottle is 10 gallon.

Pre charge pressure is 1,000 psi.

Minimum operating pressure is 1,200 psi (200 psi over pre charge pressure)

Usable fluid per gallon is 5 gallon.

Safety factor require is 50 %. This safety factor may be different depending on each company’s requirement.

BOP Stack and HCR’s as listed below:

 Equipment  Gallon to open  Gallon to close
 Annular Preventor  4.0  4.5
 Upper Pipe Rams  3.0  3.5
 Blind Shear Rams  3.5  4.0
 Lower Pipe Rams  3.0  3.5
 Choke HCR  0.5  0.5
 Kill HCR  0.5  0.5

Please follow the steps below for calculation

 1. Determine total volume require to close all of equipment

Volume = 4.5+3.5+4+3.5+0.5+0.5 = 16.5 gallon

2. Volume accounted for safety factor

Volume = 16.5 x 1.5 = 24.75 gallon

3. Determine numbers of accumulator bottles required to meet volume determined in step#2

Number of bottles = volume ÷ usable fluid per bottle

Number of bottles =24.75 ÷ 5 = 4.95 so you round it up to 5 bottles

In order to close all BOP as per requirement without any assistance of electric and pneumatic pumps, you need to have a total of 5 accumulator bottles.

You will see that based on the calculation above, determining required Koomey bottles is quite straight forward. Thing to remember is that you must use closing volume not opening volume. I see many people using the wrong figures. Even though it may not have big impact on the final result, you need to select the right figures for calculation. Moreover, the safety factor may be different based on the regulations of your working area or your company policy.

Reference books: Well Control Books

Related Post

Mechanism of Accumulator (Koomey Unit) This topic describes how an accumulator (Koomey Unit) works. First of all, I will start with accumulator bottles. The accumulator bottles are used to ...
What is Tertiary Well Control? Can you imagine if primary and secondary well control are failed? Well is flowing all the time so how can we deal with this situation? For this situat...
What is a trip tank? Trip Tank is a small metal tank with small capacity about 20-40 bbls with 1 bbl divisions inside and it is used to monitor the well. There are several...
How to Prevent Well Ballooning This topic will you describe how to prevent well ballooning. There are several items that you can manage in order to prevent or minimize well ballooni...
Share the joy
  • 735
Tagged , , . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

6 Responses to Calculate Bottles Required for Koomey Unit (Accumulator Unit)

  1. ghanem says:

    how could the Safety factor require is 50 % converted to 1.5 ??

  2. oliver Patrick says:

    I need safety information on Koomey Unit, mud pumps, well control. in short Safety information on HSE drilling operations

  3. ignatius says:

    Thanks for this info. Honestly, I just learnt this today.

  4. ignatius says:

    What size of BOPs are we using for this calculation ?

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.