# Understand shoe pressure – Top of Gas Kick Below the Shoe

I would like to address about the shoe pressure concept while while circulating gas influx out of wellbore. This is the fist scenario – Top of the gas kick below the casing shoe

The hydrostatic pressure above the casing shoe remained constantly because the fluid column is the same. The over all hydrostatic pressure in the well will decrease because gas expansion when it is being circulated. In order to maintain the bottom hole pressure constant, casing pressure will increase to balance the loss of hydrostatic pressure in the wellbore due to expansion.

You can express in term of an equation below;

bottom hole pressure = casing pressure + hydrostatic pressure in the annulus

Let’s take a look at casing shoe and we can write the relationship as follows;

pressure at shoe = hydrostatic pressure above shoe + casing pressure

If the gas influx is still below the casing shoe, the hydrostatic pressure is the same and the casing pressure will increase; therefore, pressure at shoe will increase and the shoe pressure will reach the highest pressure when the gas influx reaches the casing shoe.

Conclusion:Shoe pressure will increase until the top of the bubble reaches the casing shoe.

Ps – assumptions : water base mud is used and kick is gas.

Reference book: Well Control Books

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### 4 Responses to Understand shoe pressure – Top of Gas Kick Below the Shoe

1. jimoh idris says:

I have one important question;
HW CAN ABOUT 10000FT OF ELECTRIC LINE CABLE BE FISHED IN A CASED HOLE.

WELL DETAILS:

TD-10100FT MD
MAX DEVIATION : 34 DEG @ 6004FT MD.
THE HOLE IS DRILLED IN 3 HOLE SECTIONS WITH 9 5/8″ CASING BEING THE LAST CASING.

• This case you may need to fish with wire spear first. You cannot catch the fish with normal grappers at all due to wire in hole.

Best regards,
Rachain J

2. deen says:

Hello there,

I am currently an intern at one of the E&P companies in Malaysia under the department of Drilling Engineering. The task that I have been given is to find the casing shoe strength,
when the current mud weight is 10ppg, casing shoe depth = 3683ft, TD = 5718ft, there is a presence of kick with a gas volume of 20 bbl, the casing is 8-1/2″ . How do I calculate for casing shoe strength? well is assumed to be vertical

An explanation to solve this problem would be much appreciated!

• You should get LOT at shoe prior to drilling ahead. With the information provided by you, I cannot determine casing shoe strength.

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