#  > Petroleum Industry Zone >  > Drilling And Workover >  >  >  Casing Design

## vanket

Can someone help me about my research. I would like to learn the concepts needed for casing design, but i don't know where to start. 


I hope for everyone's kind assistance. Thanks!See More: Casing Design

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## zambroata

Hi Vanket,

the best way to start is to have a basic understanding the purpose of each casing string installed in a well. once you familiar with the name, common  size, grade , then you'll go the geometry of the well itself with respect to the available size. After understanding this, you may go to the engineering calculation. all these are available in the internet..for theory and practical, i would suggest to you Hussein Rabia well engineering material.

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## BOUGHELOUM

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## BOUGHELOUM

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## vanket

Thanks for the help guys! I've read the two books and it was very helpful. But i'm having a problem for deviated and horizontal wells, I don't know how to solve for collapse and burst??

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## BOUGHELOUM

use TVD depth to calculate collaps and burst

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## vanket

Ohw.. i see! Thanks! can you give me an example solution for horizontal well? I still can't imagine the process for horizontal well. I really appreciate your help. Thank you very much!

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## BOUGHELOUM

open this book ''Rahman - Casing Design, Theory and Practice'' and go to ''Chapter 4'' there is an exemple

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## vanket

Thanks! By the way, i'm having a problem about reference point. In rabia, what is pressure in surface? is it RKB or at the wellhead? Where is the reference point? How about in subsea and offshore rigs?

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## BOUGHELOUM

i worked only in onshore (land rig), the reference point is wellhead (landed point of casing in casing hanger)

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## vanket

Ohw! Thank you sir! your a great help. I was very confused between ground level, RKB, mean sea level, wellhead.. hehe. Because i've read the example from rabia, the part where the burst from pressure testing was calculated. Why was the back up gradient 0.465x2200? Should it be 0.465x(2200-60)?
the MSL=60'
GL or seabed=140'
the casing shoe depth=2200'
reference point:RKB

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## BOUGHELOUM

there is an error the true value of back up is  0.465x(2200-60)

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## vanket

Thanks again! By the way, what is RKB-Subsea? and what is Wellhead Growth Index?

See More: Casing Design

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## yudhi

Dear everyone....

I also read Rabia book regarding casing design, and i try to compare with another book about this same topic. but so far, all collapse and burst calculation is intended to determine weight and grade of each casing (either conductor, intermediate, production, etc)...

lets say if i wanna do casing design and i have well data as an input for grade and weight determination by collapse burst calculation, so what about the casing programme??? whats the reason to choose eg. 30/24/20/16  OD for conductor and others casing/tubing OD....

so far, i only saw that all calculation have mention already about casing progamme how to determine OD casing???

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## vanket

yudhi, I do not really know the right answer, but there is a hole size selection chart that can be seen from other books. I think that experience is one factor in choosing OD, but there are many considerations, like choosing a slim hole might be economical but has some disadvantages in well completion stage. Well i know what's your point, i've read many books about casing design and i've never seen calculations to determine the right OD. I prefer using programming, and do some randomization to find the best value my program can give, that will satisfy the conditions given, of course it must be economical. 
I'm just a student and very new to this but that's all what i got for now.

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## vanket

yudhi, I do not really know the right answer, but there is a hole size selection chart that can be seen from other books. I think that experience is one factor in choosing OD, but there are many considerations, like choosing a slim hole might be economical but has some disadvantages in well completion stage. Well i know what's your point, i've read many books about casing design and i've never seen calculations to determine the right OD. I prefer using programming, and do some randomization to find the best value my program can give, that will satisfy the conditions given, of course it must be economical. 
I'm just a student and very new to this but that's all what i got for now.

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## jdmacbook

Hi- the basic approach when designing casing strings is to start at the bottom and work back- keeping in mind that it is always nice to have a "contingent" string available if you are expecting hole problems. So step one should be to define your objectives for the lowermost casing string wrt sizes, then using your pressure data plots work back from there. Select the most economical hole and casing sizes as you select each string, again refer to your hole / casing size charts . There should be examples of this in all design manuals.

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## oxygen21

Hi,

I have some questions regarding the casing make up torque.
1) API or Non-API does effect the make up torque?
2) Can someone explain me about connections ; BTC, VAMTOP, VAGT, BLUE,etc
3) Different connections has different torque?
4) If you have spread sheet for the torque, kindly share me.

Thanks

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## yudhi

hi oxygen21,

i share what i know:
1. make up torque always specify by thread manufacturer (premium thread), for API connection also regaulted in API itself. you can read either API 5B or API 5C1 (i forgot which api it belong to, but i've seen it.)
2. BTC (currently become BC) is buttress [API connection], VAMPTOP and others are premium thread.
3. yes. like my no.1 explanation.
4. you can search to specific thread, those manufacturer shall state that information.

hope it helps

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## mbc.engg

Thanks

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## vanket

By the way, does anybody know how to calculate the collapse rating for Non-API casings? I tried to use the API formulas for determining the collapse rating but it did not produce the right answers. I Hope someone can help me! Thanks!

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## BOUGHELOUM

look to api 5c3 paragraphe 8.4, there are a non API grade -(grades indicated without letter designation).

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## vanket

Thank you BOUGHELOUM! I've read the part you are talking about. But my problem is, when i tried to use the formulas in calulating the collapse rating of S80 and other Non-API casings from appendix B, page 349, Casing Design Theory and Practice by Rahman i did not get the same results.

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## BOUGHELOUM

S80 is a special grade and collaps limit is defined by manufacturer not by API formula.

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## vanket

I see! that's why i can't get the same result. So there are no formulas for these type of casings, and are always specified by the casing manufacturers? But that was a great help! Thanks for the information!

See More: Casing Design

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## BOUGHELOUM

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## vanket

Thanks again! By the way, do you have any casing price list besides the price list from Casing Design Theory and Practice by rahman? I need more data about it. I hope you can help me.

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