Calculation of the THP

[MarteJupiter]

I am a new engineer. One of the wells during a zone completion the shut in pressure wasn't measured due to almost immidiate gas flow from the formation, now in order to calculate the size of choke and other facilities I need to have an idea of the surface pressure. I have my FRT report, that is giving me the P* pressure, no gradient available neither. How I can stimate the Shut-in pressure? or a THP "Tubing Head Preassure"?

 

[ppata]

Hi,
verify the gradients for same age in a reservoir in the neighborhood or explain again the situation. I'm a little confused.

Best regards,
Andrei

 

[Alph]

P* - is that downhole pressure / reservoir pressure?

Maximum shut-in pressure can be estimated by assuming a gas column in the tubing, known reservoir pressure, known tubing length (True Verticle Depth).

However calculating the flowing THP is more difficult. You need to know the PI, reservoir pressure to give you the bottom hole flowing pressure. From this you will have to calculate the losses in the tubing to give you the flowing THP for a given flow.

For choke sizing you also need to know the downstream pressure (choke DP) to calculate the required Cv.

Al

 

[25362]

As an aside, sometimes solid S[sub]8[/sub] has appeared and deposited affecting flow instrument readings. S[sub]8[/sub] forms as a result of reaction of sulfur compounds (H[sub]2[/sub]S, mercaptans, COS) with oxygen-containing compounds such as CO[sub]2[/sub], air, and hydrates or oxides of iron.

 

[swemin]

You can also quries from drilling team for which mud weight they used during drilling this zone. They used more mud weigh to avoid gas kick or blow out. And it can be convert to bottom pressure. But it is just estimated one as the figure will be much more than actual.